Microkalanjiyam

 

 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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  • CASE BASED SERIES
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  • infective syndromes

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