Histoplasma capsulatum – a dimorphic fungus

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Fungi which exist in 2 separate morphological forms depending of environmental temperature

Yeast form within the body or in cultures at 37C
in the soil or in cultures at 22C

Many fungi causing systemic infections are dimorphic fungi

Examples of dimorphic fungi:

Histoplasma capsulatum
Sporothrix schenckii
Blastomyces dermatitidis
Coccidioides immitis

Extended spectrum beta lactamases (ESBLs) are enzymes that mediate resistance to extended-spectrum or third generation cephalosporins like ceftazidime, cefotaxime, and ceftriaxone and monobactams like aztreonam. ESBLs do not affect cephamycins like cefoxitin and cefotetan or carbapenems like meropenem or imipenem.

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Swine Influenza …

It is a small gram negative bacillus.
 

Haemophilus influenzae in blood agar
Haemophilus influenzae meningitis

Term referring to Mycoplasma pneumoniae.
Eaton in 1944 isolated the causative agent of primary atypical pneumonia. It had the capability to pass through bacterial filters and hence was considered to be a virus which was named Eaton agent. Later it was found out that Eaton agent was a bacteria and was named Mycoplasma pneumoniae.

Causative organism – Mycoplasma pneumoniae
Also called primary atypical pneumonia
Incubation period – 1-3 weeks
Gradual onset
usually tracheobronchitis, 1/3 develop pneumonia
usually lasts for 1-2 weeks
Mode of spread – droplet spread
favoured by close contact (famalies,  military recruits)
mycoplasma may persist in throat for 2 or more months after recovery

 
Clinical manifestations

Fever
headache
malaise
sorethroat
paroxysmal cough
blood tinged sputum

Findings on physical examination are minimal
radiography shows patchy consolidation of lower lobes – starting at hilum, fanning to periphery

 
Complications

myringitis bullosa, otitis – common
rashes
meningitis
encephalitis
hemolytic anemia

 
Lab diagnosis:

Pleomorphism refers to the existance of 2 or more structural forms in the life cycle of an organism. 
In bacteriology, it refers to the variation in the structural forms exhibited by a bacteria. Eg: Mycoplasma is a highly pleomorphic bacteria.

Fried egg appearance is found in mycoplasma colonies.
Mycoplasma colonies:

biphasic – distinct central and peripheral zones
central zone – opaque, granular – growth extending into the depth of the medium
peripheral zone – translucent, flat

Click here to view ‘Fried egg colonies of Mycoplasma’ – Image from an external source – Opens in new window

Mycoplasma