Microkalanjiyam

 

 Corynbacterium diphtheriae

Posted By Admin    on 03-08-2021    Comments (10)

  1. non-encapsulated ,Gram positive bacilli,non-motile,  non-sporing,club-shaped
  2. Chinese letter pattern
  3. 3 subtypes- gravis,intermedius ,mitis by colony morphology and biochemical testing.
  4. lysogenic bacteriophage required for the expression of exotoxin-major virulent factor
  5. B segment-builds to specific receptors on susceptible cells
  6. A segment-inhibit protein synthesis, pseudomembrane - dead cells, leukocytes and fibrin.

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 Clostridium difficile

Posted By Admin    on 07-08-2021    Comments (10)

Clostridium difficile - fewer than 5% of healthy adults stools and of 70% of healthy infants.
Antibiotic associated colitis
Disease-asymptotatic carrier
               mild diarrhoea 
               Pseudomembranous colitis
               Toxic megacolon
Characteristics :  anaerobic,spore forming, toxigenic gram positive rod
Virulent factors==>toxin production, hyaluronidase
    Both Toxin A (enterotoxin)  and Toxin B-cytotoxin -     biologically active
Diagnosis:  Antibiotic associated diarrhoea  -  who has been hospitalized for 3 or more days


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 Listeria monocytogenes

Posted By Admin    on 07-08-2021    Comments (10)

  1. Found in environment,not normal fecal flora in humans
  2. Ingestion of infected foods such as milk, soft cheese, undercooked meat, unwashed vegetables
  3. Meningitis- impaired cellular immunity such as pregnant women, neonates, patients with AIDS, post transplant on immune suppressive medications
  4. Early onset-1st 2 days of life-transplacental infection                           - Difficulty in breathing and pneumonia                     Granulomatosis infantiseptica - Severe form of listeria infection of neonates in which granulomatous rash with abscesses is evident
  5.  Late onset-2 to 3 weeks after birth -  Resembles Group B streptococci.

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 Clostridium botulinum

Posted By Admin    on 07-08-2021    Comments (10)

Botulism:

  1.          Clostridium botulinum- causes botulism
  2.          Clostridium botulinum produces powerful exotoxin- released by autolysis of the cell. Non toxic progenitor is converted by activated trypsin into active toxin.
  3.       Lethal dose 1-2 µg
  4.        Toxin resists digestion- absorbed in  active form through small intestine
  5.        It acts by blocking the production or release of acetylcholine at the synapses and neuromuscular junctions
  6.       Diplopia, dysarthria, dysphagia due to  cranial Nerve involvement
  7.       Symmetric descending paralysis



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 Bacteroides fragilis

Posted By Admin    on 07-08-2021    Comments (10)

- Clinically significant anaerobic organisms
- Part of the normal flora of tract
- Most common cause of intra abdominal infections
Diverticulitis
Inflammation of a diverticulum which is a small bulging sac in the colon wall which can trap food particles and become inflamed and painful
Characteristics
small anaerobic, Gram Negative Bacilli,Vacuolization,irregular staining, pleomorphism are common
capsule-   polysaccharides inhibits phagocytosis 
                -   Allow adherence to epithelial cells
Succinic acid- inhibits phagocytosis
Superoxide dismutase- allows the organism survive in the presence of small amounts of  O2
  


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 Borrellia burgdorferi

Posted By Admin    on 11-08-2021    Comments (10)

Lyme disease- Ixodid ticks, Primary reservoirs-small rodent white footed mouse
Bull’s eye skin lesion (Site of the tick bite)
1 to 4 Weeks past infection
Fever, fatigue,headache,arthralgia, myalgia
Charcteristics
Spirochete family of prokaryotes gram negative
-Flexible, multilayer outer cell membrane
- more rigid peptidoglycon containing cytoplasmic membrane
- between these two,layers-endoflagella
-rotation of flagella- characteristic cork screw appearance 
-micro aerophilic –doubling time 8 to 24 hours
Ixodes tick become infected on feeding with an infected animal.
-nymphal stage is more infective 


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 Campylobacter jejuni

Posted By Admin    on 11-08-2021    Comments (10)

Clinical features :eating poorly cooked chicken,although milk, water and other meats.
-most frequent cause of bacterial diarrhoea occurring most often in summer or early fall
- bloody diarrhoea, invasive to lining of intestine
- Guillian-barre Syndrome-acute demyelinating disease
-Antigenic similarities between LPS on surface of some serotypes of Campylobacter jejunii and myelin proteins responsible for the disease
Campylobacter coli ->Gastro enteritis
Campylobacter fetus- Bacteremia, septic arthritis,peritonitis,abscesses,meningitits,endocardidits(immuno-compromised

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 Chlamydia trachomatis

Posted By Admin    on 11-08-2021    Comments (10)

- Gram negative obligate intracellular parasite
- Coccoid in morphology,350 nm in diameter
Life cycle
1. Elementary body attaches to host cell
2. Host cell phagocytoses the elementary body residing in a vacuole inhibiting phagosome- lysosome fusion
3. Elementary body reorganizes to form a reticulate body 
4. Reticulate body divides by binary fission
5. Some reticulate bodies convert back into elementary bodies;elementary bodies are released into host cell
[Elementary body]
Non dividing 300 nm infectious particle with an outer membrane with disulfide linkage that allows it to survive extracellularly 
Chandelier sign
Severe cervical motion tenderness  during bimanual exam characterisitic of Pelvic infammatory disease

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 Pseudomonas aeruginosa

Posted By Admin    on 11-08-2021    Comments (10)

Ubiquitous aerobic gram negative bacillus
- Polar flagella, moist areas
- Reservoirs in  a hospital include sinks, toilets,mops,respiratory  therapy and dialysis equipment
- Intrinsic resistance to many antibiotics and disinfectants
- Polysaccharide capsule- adhere to epithelial cells
- Cystic fibrosis-mucoid-presence of capsule 
- Multiple toxins and enzymes
- Mutations of these porin proteins   -  antibiotic resistance
(antibiotic entry into bacteria these pores
Multidrug efflux pumps and β lactamase producers
Diffusible pigment Pycocyanin- blue colour(flourescin yellow)
Pyorubin(red-brown colour)

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 Haemophilus influenza

Posted By Admin    on 11-08-2021    Comments (10)

Conventional blood agar not suitable for recovery of Haemophilus species that require v factor for growth because of the presence of v factor- inactivating enzymes in native sheep blood. Rabbit or horse blood does not contain these enzymes and agar media containing either of these blood products support the growth of most haemophilus species at 35-37ºC in a moist environment and increased CO2(5.7%)

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 Gardnerella Vaginalis

Posted By Admin    on 11-08-2021    Comments (10)

Gram +ve, Gram –ve, Gram variable
  1. PG-> 20% of total cell wall weight E.coli -23%
  2. Don’t contain compounds Normally present in gram negative cell wall LPS
  3. Eg.meso-DAP,2-Keto-3-deoxy-D-manno-2-octonoic acid,hydroxyl fatty acids
  4. (meso-DAP,arabinogalactans,mycolic acid) absents confirms distinct from gram +ve cell wall type found in corynebacterium spp
  5. Digests of G.vaginalis cell wall-alanine, glutamic acid,glycine,lysine,glu,gal, 
Virulence factors
  1. Fibrillar exopolysacchride-adherence of organism to vaginal epithelial cells
  2. Pili-mucosal adherence
  3. Extracellular cytolysin-mw 59 to63 KDa,specificity for human RBCS,100 fold higher content of this cytolysin-> lysis of other animal RBCs,lyse endothelial cells,PMNs
  4. Cytolysin-specific IgA is vaginal fluids of women bacterial vaginosis
  5. Phospolipase C lecithin-phosphorycholine +1,2 - diglyceride.                                         

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 Staphylococcus aureus

Posted By Admin    on 12-08-2021    Comments (10)

·        

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 Mycobacterium tuberculosis

Posted By Admin    on 28-08-2021    Comments (10)

Morphology & Identification:
Thin straight rods 0.4*3μm.
Constituents of tubercle bacilli:
Cell wall 
a) Lipids - Mycolic acids long chain fatty acids (78-90C) waxes, Phosphatides.
b) Muramyl dipeptide (from PG) + mycolic acids ->Granuloma.
c) Phospholipids – Caseous necrosis.
d) Lipids – acid fastness.
e) Serpentine cords – AFB (acid fast bacilli) parallel arrangement cord formation- virulence cord factor (trehalose-6, 6’- dimycolate) – inhibits migration of leucocytes, - chronic granuloma. 

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 LONG QUESTIONS

Posted By Admin    on 02-09-2021    Comments (10)

Describe the morphology life cycle, pathogenesis and laboratory diagnosis of Echinococcus granulosus.
Dog tape worm (or) hydatid worm
Definite host - Dog
Intermediate host - Sheep and humans.
- Small tapeworm 3-6 mm length
- Scolex, short neck
- 3 proglottides -anterior immature
                                        Middle mature
                                          Posterior gravid
- Scolex - pyriform with 4 suckers - prominent rostellum bearing two circular rows of hooklets.
- Terminal proglottid - filled - branched uterus with eggs.

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 High level disinfection in hospitals

Posted By Admin    on 03-09-2021    Comments (10)

High level disinfection in   Hospitals:
- A chemical that kills all  microbial  pathogens except large numbers of spores
- They have some activity against a small number of  spores, if  the contact time is increased
- Example. H2O2, Gluteraldehyde
Aldehydes- Sporicidal
- Glutaraldehyde- low temperature disinfection 
- Sterilization of endoscopes and surgical equipment
- 2% solution
Halogen- releasing agents
- Chlorine releasing agents- sodium hypochlorite, chlorine dioxide and sodium dichloroiso-cyanurate
- Oxidizing agents- destroy the cellular activity of proteins
- Hypochlorous acid- active compound- bactericidal and virucidal effect
- At higher concentrations- these compounds are sporicidal
- Iodine is rapidly bactericidal, fungicidal tuberculocidal, virucidal and sporicidal
Peroxygens:
- H2O2- Broad spectrum activity against viruses, bacteria, yeasts and bacterial spores
- Sporicidal acitivity- higher concentration (10-30%) of H2O2 and longer contact times

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 Atypical mycobacteria

Posted By Admin    on 03-09-2021    Comments (10)

Atypical mycobacteria
Mycobacteria other than tubercle bacilli occasionally cause human disease
Runyon classification
Group I photochromogens
Group II scotochromogens
Group III non photochromogens
Group IV rapid growers
Group I photochromogens:
- Form yellow orange pigment- exposed to light for one hour 24-28 hours
- No pigment in dark
Mycobacterium kansasii
- Chronic pulmonary disease resembling tuberculosis- upper lobe cavity and scarring
Mycobacterium marinum (swimming pool or fish tank granuloma)
Differentiated from kansasii
- Poor growth at 37ºc
- Negative  nitratase
- Positive pyrazinamide L-fucosidase activities
Group II Scotochromogens:
- Pigmented colonies (yellow, orange, red) in dark
M. scrofulaceum- scrofula (cervical adenitis) in children
Mycobacterium gordonae- tap water scotochromogen
Group III non photochromogens:
- Strains do not form pigment even on exposure to sunlight
- Mycobacterium avium intracellulare (MAC)
- Lymphadenopathy, pulmonary lesions or disseminated disease (AIDS)
Group IV Rapid growers:
- Strains capable of rapid growth, colonies appearing within seven days of incubation at 37ºc to 25ºc
- M. fortuitum and M.chelonae
- Chronic abscesses

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 Sporotrichosis

Posted By Admin    on 04-09-2021    Comments (10)

Sporotrichosis (Subcutaneous mycoses)

  -Caused by fungus Sporothrix schenckii (Saprophyte)

Acquired through thorn pricks or other minor injuries

Fungus spreads from primary site (upper limb) through lymphatics

 Does not extend beyond regional lymph nodes

 Development of nodules in skin, subcutaneous tissues and in lymph nodes

Nodules breakdown to form indolent ulcers- chronic granulomatous disease

Diagnosis

Culture (sabourauds’ agar with antibacterial antibiotics)

Sporothrix (dimorphic fungus)

Yeast phase in tissues and in cultures 37ºC

Mycelia phase in  nature and in cultures at room temperature

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 Lab diagnosis of urinary tract infection

Posted By Admin    on 04-09-2021    Comments (10)

Lab diagnosis of Urinary tract infection:
Collection:
Midstream urine
- Patient is advised to clean the external genitalia, and to collect the midstream of urine into wide mouthed, screw capped, leak proof, sterile universal container
- Supra pubic aspiration
- Early morning urine (tuberculosis)
Transport:
Transported in container with 1.8% boric acid- can be kept for 24 hours 
Etiological agents
Bacterial
- Enterobacteriaceae- Escherichia coli commonest
- Enterococci
- Staphylococcus aureus and coagulase negative Staphylococcus
MICROSCOPY
Griess nitrite test
Detects presence of 
Catalase test
Triphenyltetrazolium chloride TTC (Test)
Pink red precipitate- respiratory activity of bacteria
Gram stain
Dip slide culture
- Agar coated slides- exposed to stream of urine and incubated
- Growth estimated by colony counting or colour change of indicator.
Culture
Semiquantitative
- Blood agar, Mac conkey agar cysteine Lactose Electrolyte Deficient Agar CLED agar.
- CFU or colony count- 10*5ml significant if < 10*3/ml- significant if
- Prior antibiotic administration
- Obstruction of urinary tract
- Suprapubic aspiration 
- Fungal infection  and pyelonephritis
Antibiotic sensitivity: (AST)
Disc Diffusion Test
Primary susceptibility test with  urinary specimen
- Confirmed by AST using bacterium grown in culture

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 Morphology and Lab diagnosis of Kala -azar

Posted By Admin    on 04-09-2021    Comments (10)

Morphology and lab  diagnosis of Kala-azar
Causative agent : Haemoflagellate -Leishmania donovani
Amastigote
- In humans
- Ovoid or rounded cell (2 to 4 µm)
- Intracellular (macrophages, monocytes, neutrophils or endothelial cells)
- Leishman stain- pale blue cytoplasm and nucleus is red.
Promastigote:
- Pear shaped forms (15 to 25 µm)
- Flagellum (15 to 30 µm length)
- In sandfly.
Lab diagnosis:
1.Demonstration of parasites:
a) Peripheral blood
b) Bone marrow aspirate
c) Splenic aspirate
LYMPH NODE (ASPIRATES ARE NOT USEFUL)
MICROSCOPY
- Leishman Stain- (amastigote within macrophages)
CULTURE
- Novy McNeal- Nicolle (NNN) medium.
Rabbit blood agar + Locker’ solution
- Schneider medium
Demonstration of antibodies or antigens:
a) Immunofluorescence (IFA)
b) Direct Agglutination test
c) Immune chromatographic Dipstick method
Antigen detection  tests:
- Complement Fixation  test with WKK antigen (Witebsky, Klingenstein and Kuhn)
- Antigen from Kedrowsky’s acid fast bacillus is also preferred.
3.Non specific Serum Tests
- increased globulin content of serum
Napiers’ aldehyde Test (Formal gel Test)
Chopras’ antimony test:
0.2ml serum (1 in  10 dilution with distilled water)(Dreyers’ tube)
Add 4% urea stibamine (distilled water)
Thick flocculent disc at the junction of 2 liquids
4.Montenegro (Leishmanin) skin test
- Normocytic Normochromic anaemia
- Neutropenia
- thrombocytopenia
- serum globulin level- markedly elevated
- reversal of Albumin- globulin ratio

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 Microfilariae

Posted By Admin    on 04-09-2021    Comments (10)

Microfilariae
- Filarial female adult worms are viviparous- multiply sexually- produce L1 (first stage larva (L1) larvae)
Microfilariae
Size 244 to  296 µm length, 7.5 to 10 µm in diameter
Transparent and colourless with bluntly rounded anterior end and pointed tail end (unstained specimens)
Covered by hyaline sheath, larvae move forwards and backwards within  this sheath
Along central axis- column of granules- somatic cells or nuclei, tail  end  does not have nuclei
Few anatomical landmarks
Nerve ring
Excretory pore
Excretory cells
Gulls
Analpore

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 Cryptosporidium parvum

Posted By Admin    on 04-09-2021    Comments (10)

CRYPTOSPORIDIUM PARVUM
- Acute self limited diarrhoea in healthy individuals
- Chronic life threatening diarrhoea in immunocompromised patients
- Minute coccidian parasite
Clinical picture:
- In healthy persons- asymptomatic or self limited febrile illness with  watery diarrhoea
Childhood and travellers diarrhoea
- Immunosuppressed
Severe protracted diarrhoea, fever emaciation.
In  AIDS invade bronchial, biliary tracts- parasite demonstrated in  sputum
Lab diagnosis:
Demonstration of oocyst in faeces 
a) Jenner- Giemsa stain
a. Oocyst- blue spherical bodies with a few eosinophilic granules
b) Cold ziehl- Neelsen  technique
a. Internal   structures acid fast
c) Indirect immunofluorescence
If oocysts are scanty- concentration  by formol- ether technique used
Prevention:
- Sequential  application  of   ozone and chlorine of  drinking water
Treatment:
Nitazoxanide 500mg BD
For 2-5 days

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 Primary meningoencephalitis

Posted By Admin    on 04-09-2021    Comments (10)

Primary amoebic meningoencephalitis
- Caused by Naegleria fowleri (free living amoebae)
Life cycle:
3 stages
(amoeboflagellate)
1. Dormant cyst form
2. Amoeboid trophozoite form
Life cycle  of Naegleria fowleri
Host  
Infective form
(trophozoite flagellate)
Cyst
Trophozoites- neurotrophic
Enter the nose -Olfactory nerves and olfactory bulbs -Penetrate the submucosal  nervous plexuses- Cribriform plate-Subarachnoid space-Enter ventricular system- foramen of  Luschkha and Magendie-Reach the choroid  plexus
---Acute ependymitis
- Acute purulent meningitis and encephalitis (primary amoebic meningoencephalitis)
Clinical  features:
- Incubation  period: 2 days to 2 weeks
- H/o bathing, swimming, diving, playing in  warm stagnant freshwater
- Symptoms mimic acute bacterial  meningitis
- Sudden  severe and persistent bifrontal  or bitemporal headache
- Nausea, projective vomiting, fever stiff neck, mental status change and seizures
- Fatal
Mode of transmission
- Inhalation of  dust and aspiration of water contaminated with  both cysts  and trophozoites
- Inhalation or aspiration of aerosols containing cysts
Diagnosis:
Cerebrospinal  fluid
Microscopy:
- Phase Contrast Microscopy
(active directional movement)
- Giemsa stain
Culture:
- Non nutrient Agar plates- with lawn cultures of Escherichia coli
- Trails left by migrating amoebae- after 2 or 3 days
Molecular identification:
DNA probes

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 General microbiology

Posted By Admin    on 22-09-2021    Comments (10)

1.Louis pasteur is not associated with
  • introduction of complex media
  • Discovery of Rabies vaccine
  • Discovery of M.tuberculosis
  • Disproved spontaneous generation theory.
2.All of the following pathogenic bacteria fulfill Koch’s postulates except
  • Treponema pallidum
  • Yersinia pestis
  • Bacillus anthracis
  • Helicobacter pylori

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 General microbiology

Posted By Admin    on 22-09-2021    Comments (10)

3.The cell organelle analogous to mitochondria in prokaryotes is 
  • Plasmid
  • Transposons
  • Mesosomes
  • 70s ribosomes
4.Dark ground microscopy is used to see
  • Refractive organs
  • Flagella
  • Capsule
  • Fimbriae

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 General microbiology

Posted By Admin    on 22-09-2021    Comments (10)

5.All are acid fast except

  • Nocardia
  • Bacterial spores
  • M.leprae
  • Mycoplasma

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 General microbiology

Posted By Admin    on 22-09-2021    Comments (10)

6.In negative staining 
  • the structure to be demonstrated is stained
  • the structure to be demonstrated is not stained
  • The background is not stained
  • The background and the structure are stained


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 General microbiology

Posted By Admin    on 22-09-2021    Comments (10)

7.The bacterial nuclear nucleoid differs from eukaryotic nucleus by all of the following except

  • G+C content
  • Histone proteins
  • Introns
  • Ploidy

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 General microbiology

Posted By Admin    on 22-09-2021    Comments (10)

8.Lipopolysaccharide is a component of cell wall of 

  • Gram +ve bacteria
  • Gram -ve bacteria
  • Virus 
  • Fungi

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 General microbiology

Posted By Admin    on 22-09-2021    Comments (10)

9.The difference between Gram +ve bacteria &

Gram -ve bacteria organism is the Gram -ve bacteria contains
  • Teichoic acid
  • Muramic acid
  • N –acetyl muramic acid
  • Aromatic aminoacids

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 General microbiology

Posted By Admin    on 22-09-2021    Comments (10)

10.Capsulated  organism 
  • Candida 
  • Klebsiella
  • Proteus
  • Cryptococcus

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 General microbiology

Posted By Admin    on 22-09-2021    Comments (10)

11.The organism that is strongly urease positive 

  • Proteus
  • Klebsiella
  • Helicobacter pylori
  • Staphylococcus

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 Strongyloides stercoralis

Posted By Admin    on 26-10-2021    Comments (10)

Is a small nematode 
Adult female worm is parthenogenetic
Female worm lies in small intestine, lays eggs which immediately hatches into rhabditiform Larvae - passes in stool
Auto Infection- in which rhabditiform Larvae  moults into filariform Larvae in perianal skin and enters into blood vessels
Direct development  - rhabditiform Larvae  moults into filariform Larvae in soil enters through foot and into blood vessels 
Indirect development  -rhabditiform Larvae  moults develops into free living male and female - eggs - rhabditiform Larvae-filariform Larvae- Penetrate skin and enters blood vessels 
From the blood vessels  - enters right heart and lungs - alveolar capillaries- alveoli - ascends ,enters pharynx and swallowed - small intestine- Adult female worm lays eggs 

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 Stages of biofilm formation and definition

Posted By Admin    on 26-10-2021    Comments (10)

Definition : Biofilm is a consortium of bacteria or other microbes organized within an extensive exopolysaccharide exopolymers

Five stages : 
reversible attachment
irreversible attachment
maturation 1
maturation 2
dispersion
Bacterial cells in biofilm microcolonies are held together by a slime like matrix.This matrix is chemically complex including polysaccharides ,nucleic acids and proteins.

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 superfamily - Trichuroidea

Posted By Admin    on 30-10-2021    Comments (10)

  1. birds - definitive host
  2. humans - intermediate host -harbouring infective larvae
  3. clinical features - malabsorption syndrome ,severe diarrhoea ,borborygmi and abdominal pain
  4. Diagnosis - detection of eggs,larvae and adults in stool
  5. eggs resemble Trichiuris trichiura but smaller
  6. Treatment - mebendazole

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 Intestinal flukes

Posted By Admin    on 30-10-2021    Comments (10)

 

 Ascaris of sea mammals

Posted By Admin    on 30-10-2021    Comments (10)

  1. anisakiasis - common in Japan -where fresh or undercooked fish is popular
  2. nematode of sea mammals -dolphins, whales  - eggs passed in sea water  -infect crustaceans - eaten by fish which harbors infective larvae
  3. humans acquire infection by eating partially cooked or fresh infected fish
  4. larvae penetrate the gut wall - eosinophilic granuloma of bowel

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 liver flukes

Posted By Admin    on 30-10-2021    Comments (10)

 

 potassium hydroxide preparation - 10%

Posted By Admin    on 30-10-2021    Comments (10)

  1. KOH is added to the specimens like nail,hair,skin scrapings and sputum (40% for nail) - 
  2. wet mount technique and seen under 10 X,40X 
  3. after adding KOH ,specimen is allowed to digest for 5 - 10 minutes 
  4. rapid detection of fungal hyphal elements
  5. demerits - experience requires to differentiate from artifacts,nails may require 1 day to digest

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 Antimicrobial action

Posted By Admin    on 31-10-2021    Comments (10)

  1. Bacteriostatic agents : Antimicrobial agents that inhibit bacterial growth but generally do not kill the organism
  2. Bactericidal agents : Agents that usually kill target organisms .
  3. basic steps in antimicroial activity - active drug,anatomic approximation,surface binding ,intracellular uptake ,target binding results in either   growth inhibition or lysis and death              

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 Mechanisms of Resistance

Posted By Admin    on 05-11-2021    Comments (10)

1.Enzymatic inactivation : Beta -lactamases ,penicillinases

 ,cephalosporinases,carbapenemases,aminoglycoside modifying enzymes
2.Altered receptors : altered penicillin binding proteins of Gram positive and Gram negative bacteria,ribosomal alterations (tetracycline,erythromycin,aminoglycosides),DNA gyrase alterations (quinolones) and altered bacterial enzymes (sulfamethoxazole,trimethoprim)
3.Altered antibiotic transport : decreased influx,active efflux

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 Microorganism mediated antimicrobial resistance

Posted By Admin    on 05-11-2021    Comments (10)

Antimicrobial resistance  due to genetic traits of organism and to be detected by in -vitro susceptibility testing methods. It is of two types 1.intrinsic 2.acquired

1.Intrinsic resistance :
resistance due to normal genetic ,structural,or physiologic state of a microorganism
Examples :
1.aminoglycosides - intrinsically resistant to anaerobic bacteria due to lack of oxidative metabolism 
2.Aztreonam - intrinsically resistant to Gram positive bacteria due to lack of penicillin binding proteins 
3.Pseudomonas - intrinsically resistant to sulfonamides,trimethoprim,tetracycline  or chloramphenicol  - inability to achieve effective intracellular concentrations.
4.Klebsiella - intrinsically resistant to ampicillin  due to beta - lactamases
5.Vancomycin against Gram negative bacteria - drug unable to penetrate outer membrane

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 definition ,classification,epidemiology,pathogenesis,microbiology

Posted By Admin    on 05-11-2021    Comments (10)

Infective endocarditis is a microbial infection of endocardium ,generally of a heart valve or valves ,but chordae tendinae or at the site of a septal defect  or other congenital abnormalities

Classification : acute,subacute or chronic  -  related to usual course of untreated disease,
Acute form - fulminating infection,high fever,severe malaise ,leukocytosis ,rapid destruction of heart valves.Virulent organisms - Staphylococcus aureus,Streptococcus pneumoniae ,Streptococcus pyogenes,Neisseriae gonorrhoeae without treatment  - fatal,death within 6 weeks
Subacute form - infection with unspecific clinical findings and indolent course with death from the disease occurring after 6 weeks to 3 months.
 Chronic form - occurring after 3 months and upto 2 years
Epidemiology - Rheumatic  heart  disease ,congenital heart disease  ,arteriosclerotic disease - structural damage - turbulence of blood flow - endocardial damage
-idiopathic hypertrophic subaortic  stenosis
mitral valve prolapse ,mitral valve regurgitation
haemodialysis shunts ,intracardiac pacemaker wires ,central venous catheters
Nosocomial infective endocarditis -
1.intravascular access for haemodynamic monitoring
2.administration of fluids
3.long term hyperalimentation  and dialysis
4.advanced age ,surgical wounds ,genitourinary instrumentation,major abdominal surgery,implantation of prosthetic valves and cardiac devices,major burns 
can affect both previously normal and damaged heart valves  as well as prosthetic heart valves
Staphylococcus aureus in native valve endocarditis
Staphylococcus epidermidis - foreign body endocarditis
Fungal endocarditis - infected intravenous catheters 

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 case based series - Toxoplasma

Posted By Admin    on 07-11-2021    Comments (10)

A 28 year old primi (fond of cats)  ,5 months of gestation,complaints of fever,headache ,myalgia,enlargement of cervical lymph nodes.She has cleaned her cat's litter box 1week before without proper precautions.How will you manage her?Is there any risk for fetus?

1.It is probably a case of Toxoplasmosis caused by Toxoplasma gondii  which is an obligate intracellular parasite affecting  reticuloendothelial cells,muscle cells and intestinal epithelium
2.only protozoan where all the stages are infective - tachyzoite,bradyzoite and oocyst
3.Cats are definitive hosts
4.Humans and other warm blooded animals are intermediate hosts
5.trophozoite(tachyzoite) -crescent shaped - 7x3 Î¼m in size ,it invades any nucleated cell and multiplies asexually by endodyogeny or internal budding
6.Tissue cyst (bradyzoites) - chronic phase of infection,occurs in muscles,brain and other various organs,cyst size is 10 to 200 Î¼m
7.oocyst - formed in intestine of cats - after fertilization - zygote forms - oocyst with sporoblast divides into 2 sporocyst each containing 4 sporozoites .mature oocyst containing eight sporozoites is the infective form

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 case based series 2

Posted By Admin    on 12-11-2021    Comments (10)

 

 infections of blood

Posted By Admin    on 12-11-2021    Comments (10)

Infections of the blood
Bacteremia and Septicemia :
Septicemia : Sepsis is a clinical syndrome characterized by fever,chills,malaise,tachycardia,hyperventilation and toxicity or prostration.Septicemia results when circulating bacteria multiply at a rate  that exceeds their removal by phagocytes.The symptoms are produced by microbial toxins and/or cytokines produced by inflammatory cells.
Types of Bacteremia:
• Transient
• Intermittent
• Continuous
Transient bacteremia : Normal flora is introduced into the blood stream by minimal trauma to membranes(e.g., brushing of teeth,straining during bowel movements , or medical procedures).
Intermittent bacteremia : bacteria from an infected site are periodically released into the blood from extravascular abscesses ,spreading cellulitis,or infections of body cavities,such as empyema,peritonitis,or septic  arthritis .
Continuous  bacteremia :occurs when the infection is intravascular,such as infected endothelium(bacterial endocarditis or aneurysms) or infected hardware (arteriovenous fistulas,intraarterial catheters,or indwelling canulas).


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 BIOMEDICAL WASTE MANAGEMENT

Posted By Admin    on 07-12-2021    Comments (10)

BIOMEDICAL WASTE MANAGEMENT 
1.Biomedical waste (Management &Handling) rules was first proposed in 
    1.1997                2.1998                              3.1999                  4.2000
2.Plaster of Paris is  disposed of in 
   a.Yellow   bag     b.Red    bag    c.Blue  bag            d. Green          bag
3.Can improper waste  management cause various health concerns  ?
1.Yes                        2. No                                    3.Dont know
4.Correct sequence of biomedical waste management  ?
a. segregation –collection & storage – transportation – treatment & disposal
b.collection  - segregation – transportation – treatment & disposal
c. Don’t know
5.Biomedical waste handlers should
a.Be made aware of risks involved in biomedical waste
b.Use appropriate PPE
c.Both of above
d.None of above
6.Outdated and expired medicines should be disposed in
a.Yellow   bag     b.Red    bag    c.Blue  bag            d. Black         bag
7. Is Needle stick injury a health hazard ?
a. Yes                        b. No                                    c.Dont know
8.Techniques used in waste treatment are all except
a.Double chambered incineration
b.Autoclaving
c.microwaving
d.landfill
9.Goggles used in Covid 19 ward should be disposed in
a.Yellow   bag     b.Red    bag    c.Blue  bag            d. Black         bag
10.Blood bags should be disposed in
a.Yellow   bag     b.Red    bag    c.Blue  bag            d. Black         bag



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 Mycetoma

Posted By Admin    on 18-12-2021    Comments (10)

heterogenous group of fungal infections  - characterized by development of clinical lesions in subcutaneous tissues at the site of inoculation of etiological agents

MYCETOMA
SPOROTRICHOSIS
CHROMOBLASTOMYCOSIS
PHAEOHYPHOMYCOSIS
RHINOSPORIDIOSIS
LOBOMYCOSIS

MYCETOMA
Slowly progressive chronic granulomatous infection of skin and subcutaneous tissues with involvement of underlying fasciae and bones usually affecting extemities
Triad – tumefaction of affected tissue,formation of multiple draining sinuses,presence of oozing granules
Granules – clusters of organisms within the infected tissues also called as grains

EUMYCETOMA
FUNGI
BLACK GRAIN EUMYCETOMA 
Madurella mycetomatis
Exophiala jeanselmei
Curvularia geniculata
White grain Eumycetoma
Pseudoallescheria boydii
Aspergillus nidulans
Acremonium falciforme
Fusarium 
Actinomycetoma
Bacterial
Actinomadura madurae
Nocardia
Streptomyces
Pathogenesis and pathology
Causative agent in saprotrophic soil – traumatic inoculation
Organisms – centre of microabscess formed by polymorphonuclear cells
Aggregates of filaments of causative organisms
LAB DIAGNOSIS
Eumycetoma
2-6μm  wide interwoven hyphae ,
Sabouraud dextrose agar

Actinomycetoma
Filamentous bacteria 0.5-1μm
Lowenstein –Jensen media


TREATMENT

Eumycetoma – itraconazole 100mg BD – 8-24 months
Actinomycetoma – Welsh regimen – amikacin & cotrimoxazole 5 weeks
Surgery – debridement of infected tissue with split graft




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 CHROMOBLASTOMYCOSIS

Posted By Admin    on 18-12-2021    Comments (10)

Chronic fungal infection of skin and subcutaneous tissue
•Phaeoid (dematiaceous )fungi
•Polmorphic,verrucoid,crusted or ulcerated lesion
Sclerotic bodies - pathognomonic
Clinical features
Verrucous lesions  -ulcerated –raised above 1-3 cm above skin  with rough irregular surfaces  -cauliflower like – verrucose dermatitis ,common in Lower leg
LAB DIAGNOSIS
KOH mount – muriform or sclerotic bodies 
Specimen – skin scrapings or biopsy specimens from dry ,crusty material
Fungal culture – SDA with actidione 
Treatment 
itraconazole 


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 PHAEOHYPHOMYCOSIS

Posted By Admin    on 18-12-2021    Comments (10)

Subcutaneous and systemic infection – caused by various heterogenous groups of phaeoid (dematiaceous) fungi
Fungi found in hyphal form in tissues
Lab diagnosis
1.KOH mounts – fungi usually pigmented – dark brown in colour 
2.Fungal culture – SDA 

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 Bacterial,viral,fungal and parasite etiology

Posted By Admin    on 19-12-2021    Comments (10)

INFECTIONS OF THE GENITAL TRACT
1.Genital tract consists of external and internal genitalia in both the sexes
2.External genitalia –penis and labia
3.Internal genitalia –male –testes, epididymis,seminal vesicles ,and urethra,prostate
4.Female – ovaries,fallopian tubes,uterus,uterine cervix and vagina with its accessory glands
URETHRITIS AND CERVICITIS 
1.Most common STI is Chlamydia trachomatis 
2.Men – pain on urination and urethral discharge (urethritis)
3.Women – mucopurulent cervicitis ,acute urethritis – PID –inflammatory scarring of fallopian tubes – infertility and ectopic pregnancy 
GENITAL ULCER DISEASE
1.Herpes simplex is commonest 
2.Vesicular lesion with an erythematous base on glans penis,vulva ,perineum,buttocks or cervix
3.Vesicles are painful –ulcerate – systemic symptoms with bilateral inguinal lymphadenopathy
Herpes virus
Important properties
Virion : spherical, 150-200nm in diameter(icosahedral)
Genome : ds DNA, linear
Proteins : >35
Envelope : viral glycoproteins, Fc receptors
Replication : Nucleus
Outstanding Characteristics
Envelope many enzymes
Establish latent infections
Reactivated in immunosuppressed hosts
Cancer causing
Classification

Herpesviriniae
α-    HSV1, HSV2, VZV- Neurons
β-CMV, HH6, HH7 -glands, kidneyslymphoid tissue
γ - EBV , KSHV - lymphoid tissue
HSV
HSV1-saliva
HSV2-sexually -restriction enzyme analysis of viral DNA
Pathology 
Cytolytic infections 
Necrosis of infected cells with inflammatory response 
Ballooning of infected cells 
Cow dry type A intranuclear inclusion bodies
Margination of chromatin 
Formation of multinucleated giant cells 

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 basic viral structure and replication

Posted By Admin    on 26-01-2022    Comments (10)

1.nucleo capsid - nucleic acid + capsid (protein)surrounded by envelope

2.nucleic acid - DNA or RNA  
3.Envelope - derived from host cell membrane
4.nucleocapsid - helical or icosahedral symmetry 

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 Viral carcinogenesis features

Posted By Admin    on 26-01-2022    Comments (10)

1.Tumor viruses cause persistent infections in natural hosts.

2.Host factors determine virus induced tumorigenesis.
3.Viruses are either direct or indirect - acting carcinogenic agents
4.Oncogenic viruses modulate growth control pathways in cells.
5.Viral markers are usually present  in tumour cells

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 Bacterial pneumonia

Posted By Admin    on 18-02-2022    Comments (10)

Type of assessment : Formative

Topic of assessment : Bacterial pneumonia
Feedback received from the student :
1.agents : Streptococcus pneumoniae,Haemophilus influenzae,Staphylococcus aureus,Klebsiella pneumoniae
2.Specimen : sputum,blood,pleural fluid 
3.Complications expected :empyema 
4.Antimicrobial therapy : Third generation cephalosporins and Vancomycin
These salient features were understood

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 life cycle of Balantidium coli

Posted By Admin    on 29-03-2022    Comments (10)

 

 Life cycle of Giardia lamblia

Posted By Admin    on 29-03-2022    Comments (10)

 

 Life cycle of Entamoeba histolytica

Posted By Admin    on 29-03-2022    Comments (10)

 

 Streptococcus pneumoniae

Posted By Admin    on 31-03-2022    Comments (10)

STREPTOCOCCUS PNEUMONIAE (PNEUMOCOCCUS)
• Gram positive diplococcus ,
• lancet shaped or arranged in chains
• polysaccharide capsule – typing with antisera
• Pneumococci readily lysed by surface active agents which removes inhibitors of cell wall autolysis
• Pneumococci – normal inhabitants of upper respiratory tract (5 – 40 % of humans)
• Pneumococci causes pneumonia ,sinusitis,ottitis media,bronchitis ,bacteremia,meningitis and other infections.

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 Biochemical reactions - Enterobacteriaceae

Posted By Admin    on 01-04-2022    Comments (10)

 

 zygomycetes - classification

Posted By Admin    on 17-05-2022    Comments (10)

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 TRYPANOSOMA CRUZI

Posted By Admin    on 18-06-2022    Comments (10)

TRYPANOSOMA CRUZI
• Causative agent of Chaga’s disease
• Trypomastigote form seen in peripheral blood 
• Amastigote seen intracellularly (multiplying form )
• Man gets infection by rubbing the bug faeces in the bite area
• Clinical features – chagoma (subcutaneous inflammatory nodule)
• Romana’s sign – painless,unilateral  oedema and conjuctitivits
• Complications –acute myocarditis and meningoencephalitis
• Chronic disease – conduction defects in the heart ,megaesophagus ,megacolon
• Life cycle – in man – amastigote –promastigote –epimastigote – trypomastigote
• In Reduviid bug – trypomastigote – amastigote – epimastigote –metacyclic trypomastigote form
• Lab diagnosis – 1.specimens – blood ,CSF,aspirate from Chagoma ,tissue specimen
• Microscopy – wet blood film,Giemsa stained smear
• Culture –NNN(Novy,McNeal and Nicolle)  at 22-24 deg C
• Serology – chronic cases
• Polymerase chain reaction 
• Biopsy 
• Animal inoculation (intraperitoneally into mice)
• Xenodiagnosis 

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 TRYPANOSOMA BRUCEI

Posted By Admin    on 18-06-2022    Comments (10)

TRYPANOSOMA BRUCEI

• Causative agent of Sleeping sickness disease
• Trypomastigote form (long slender form,short stumpy form,intermediate form)seen in peripheral blood 
• Clinical features –chancre (swelling and oedema of the bite area)
• Acute (early and lymphatic stage) –posterior cervical lymphadenopathy (winterbottom’s sign)
• Late phase and CNS involvement – sleeping sickness –chemical called tryptophol produced by trypanosome induce sleepiness – finally coma and death
• Transmission – through the bite of infected tsetse fly
• Life cycle – in man(definitive host) trypomastigote(long slender multiplying form )- intermediate form and short stumpy form – tsetse fly (intermediate host) –long slender form –salivary glands –convert to epimastigotes – metacyclic forms - man
• Lab diagnosis – 1.specimens – blood ,CSF,aspirate from lymph node ,tissue specimen
• Microscopy – wet blood film,Giemsa stained smear
• Culture –NNN(Novy,McNeal and Nicolle)  at 22-24 deg C
• Serology – chronic cases
• Polymerase chain reaction 
• Biopsy 
• Animal inoculation (intraperitoneally into mice)
• Xenodiagnosis 

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 impetigo

Posted By Admin    on 19-09-2022    Comments (10)

Initially vesicular – later crusted
Superficial infection of skin ,childhood
Group A strept,staphylococcus
HP – superficial,intraepidermal,unilocular vesicopustule
Corneal layers of epidermis – disrupted
S.pyogenes – access to subcorneal keratinocyte
M protein – binding to keratinocyte
CF – small vesicles ,narrow inflammatory halos
Pustulate & readily rupture
Purulent discharge dries – thick golden yellow stucks on crusts
Pruritus – superficial – heals without scarring 
Gram stain – GPC
Culture – S.aureus ,group A streptococci
ASO scant
Anti DNAse B elevated
Group A streptococci – M serotype (emm) genes
(2,49,52,55,57,59,60)


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 Exam related

Posted By Admin    on 01-02-2023    Comments (10)

All the best dear students


Kindly post your queries if you do want any lectures


Give  your  valuable  suggestions

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 Streptococcus pneumoniae

Posted By Admin    on 30-09-2023    Comments (10)

Gram positive diplococcus ,
lancet shaped or arranged in chains
polysaccharide capsule – typing with antisera
Pneumococci readily lysed by surface active agents which removes inhibitors of cell wall autolysis
Pneumococci – normal inhabitants of upper respiratory tract (5 – 40 % of humans)
Pneumococci causes pneumonia ,sinusitis,ottitis media,bronchitis ,bacteremia,meningitis and other infections.

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 Streptococcus pneumoniae

Posted By Admin    on 30-09-2023    Comments (10)

BILE SOLUBILITY TEST – Lysis of pneumococci occurs in a few minutes when ox bile (10%) or sodium deoxycholate (2%)  is added to a broth culture 

OPTOCHIN SUSCEPTIBILITY – growth of pneumococci is inhibited around the optochin disk.

These 2 features are used to differentiate it from other viridans streptococci

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 Streptococcus pneumoniae

Posted By Admin    on 30-09-2023    Comments (10)

ANTIGENIC STRUCTURE
Component structure – Pneumococcal cell wall has peptidoglycan and teichoic acid
Capsular polysaccharide (>90 types) – covalently bound to peptidoglycan and to cell wall polysaccharide – diffuses into media ,exudates and tissues (specific soluble substance)

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 Streptococcus pneumoniae

Posted By Admin    on 30-09-2023    Comments (10)

C –REACTIVE PROTEIN :
An abnormal protein (beta globulin) – precipitates with somatic  C antigen of Pneumocci appears in acute phase of sera ,disappears in convalescence.
It ia an acute phase substance produced in hepatocytes – its production stimulated by bacterial infections ,inflammations,malignancies and tissue destruction.
CRP testing by passive agglutination using latex particles coated with anti – CRP antibody is a routine diagnostic test.

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 Streptococcus pneumoniae

Posted By Admin    on 30-09-2023    Comments (10)

VIRULENCE FACTORS
Ig A1 protease : extracellular protease that specifically cleaves IgA1 in hinge region of upper respiratory tract.
Pneumolysin : intracellular membrane damaging toxin known as pneumolysin  (released by autolysis) inhibits neutrophil chemotaxis,phagocytosis and respiratory burst ,lymphocyte proliferation and immunoglobulin synthesis,immunogenic
Autolysin – activation leads to breaking of peptide cross linking of cell wall peptidoglycan  -lysis of bacteria  - release of large amounts of cell wall fragments  -massive inflammatory response – pneumococcal pneumonia and meningitis.
Tuftsin –naturally occurring tetrapeptide – secreted by spleen  -pneumococcal sepsis in congenital asplenia,traumatic removal ,functional impairment (eg homozygous sickle cell disease)


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 Streptococcus pneumoniae

Posted By Admin    on 30-09-2023    Comments (10)

40 – 70 % carriers of virulent pneumococci in normal respiratory  mucosa must possess great natural resistance to pneumococcus.
Viral and other respiratory tract infections that damage surface cells ,abnormal accumulation of mucus (eg allergy)- protect pneumococcus from phagocytosis, bronchial obstruction,respiratory tract injury due to irritants  disturb its mucociliary action.
Alcohol or drug intoxication  -depress phagocytic activity ,depress cough reflex  and facilitate aspiration of foreign material
Abnormal circulatory dynamics (eg pulmonary congestion ,heart failure)
Malnutrition,general debility ,sickle cell anaemia,hyposplenism,nephrosis or complement deficiency


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 Streptococcus pneumoniae

Posted By Admin    on 30-09-2023    Comments (10)

Outpouring of fibrinous edema fluid into alveoli followed by red cells and leukocytes –consolidation of portions of lungs
Pneumococci – found in exudates – blood stream – lymphatic drainage of lungs  -alveolar walls – intact
Mononuclear cells actively phagocytose the debris 
Pneumococci taken up by phagocytes  - digested intracellularly


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 Streptococcus pneumoniae

Posted By Admin    on 30-09-2023    Comments (10)

CLINICAL FEATURES :
Fever,chills,sharp pleural pain
Sputum similar to alveolar exudates (bloody or rust coloured)
TREATMENT 
Penicillin G –MIC > 2µg/ml – resistance
Vancomycin
VACCINE
Pneumoconjugate vaccine –conjugated to diphtheria CRM 197 protein 

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 Bacterial Genetics

Posted By Admin    on 31-03-2024    Comments (10)

Bacterial genetics deals with the study of heredity and gene 
variations seen in bacteria.

Bacteria possess a single haploid chromosome, comprising 
of super coiled circular double stranded DNA of 1 mm 
length.

Plasmids are the extrachromosomal ds circular DNA 
molecules that exist in a free state in the cytoplasm of 
bacteria

Independent replication: Plasmids are capable of 
replicating independently.

plasmid may integrate with 
chromosomal DNA of bacteria and such plasmids are called as episomes

Curing: The process of eliminating the plasmids from 
bacteria is known as curing

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 Bacterial Genetics

Posted By Admin    on 31-03-2024    Comments (10)

Classification of Plasmids
  • Based on ability to perform conjugation
  • Based on compatibility between the plasmids
  • Based on function
1.Fertility or F-plasmids
2.Resistance (R) plasmids
3.Col plasmids
4.Virulence plasmids
5.Metabolic plasmids

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 Bacterial Genetics

Posted By Admin    on 31-03-2024    Comments (10)

Definition: Mutation is a random, undirected heritable 
variation caused by a change in the nucleotide sequence 
of the genome of the cell

1. Spontaneous mutations: Mutations that occur naturally 
in any dividing cells that arise occasionally without 
adding any mutagen
2. Induced mutations: These mutations  are as a result of exposure of the organism to a mutagen
Mutation can affect any gene and hence may modify any 
characteristic of the bacterium, for example— 
™ Sensitivity to bacteriophages
™ Loss of ability to produce capsule or flagella
™ Loss of virulence
™ Alteration in colony morphology
™ Alteration in pigment production 
™ Drug susceptibility
™ Biochemical reactions
™ Antigenic structure.
Classification of Mutation Types 
Mutations may occur in two ways—
1. Small-scale mutations: They are more commonly seen 
in bacteria. Examples include (1) point mutations—
occur at a single nucleotide, (2) addition or deletion of 
single nucleotide pair
2. Large-scale mutations occur in chromosomal structure: 
These include deletion or addition of several nucleotide 
base pairs or gene duplications.


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 Bacterial Genetics

Posted By Admin    on 31-03-2024    Comments (10)

Types of mutations

Forward mutations 

Substitutions at single nucleotide base pair

At DNA Level

Transition It is a point mutation that changes a purine nucleotide to another purine (A ↔ G) or a pyrimidine nucleotide to 
another pyrimidine (C ↔ T)

Transversion It refers to the substitution of a purine for a pyrimidine or vice versa in DNA, (C/T ↔ A/G)
At codon level 

Silent mutation The new codon codes for the same amino acid, e.g. AGG ↔ CGG, both code for arginine

Neutral mutation The new codon forms different but functionally equivalent amino acid: AAA (lysine) AGA (arginine) 

Missense mutation The new codon codes for a different amino acid

Nonsense mutation The new codon is a stop codon which causes termination, e.g. CAG (Glutamine) ↔ UAG (stop)

Addition or deletion at single or many nucleotide base pairs

Frame-shift mutation Any addition or deletion of base pairs that is not a multiple of three results in a shift in the normal reading 
frame of the coded message forming new set of triplet codon.

Reverse mutations It is a second mutation that nullifies the effect of the first mutation and results in gaining back the 
function of the wild phenotype

True reversion • A true reverse mutation converts the mutant nucleotide sequence back to the wild-type sequence

Suppressor mutation It is a second mutation in a different gene that reverts the phenotypic effects of an already existing mutation 

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