Tuesday, 29 June 2010

Nocardia species

(speciation pending)
Bacteria, with some fungal similarities

Bronchial wash specimens sent to our laboratory were examined microscopically by gram stain. Numerous gram positive branching bacilli were observed raising suspicion of Nocardia. A partial acid-fast stain (1) confirmed suspicions that the organism was indeed partially acid-fast and consistent with Nocardia. Gram stain results and presumptive diagnosis were reported to the doctor in charge in order to initiate immediate and appropriate antimicrobial therapy. The bronchial wash specimen was cultured on our routine media (Blood, Chocolate, & MacConkey agars) to which Sabaraud-Dextrose & New York City agars were added. Specimens were incubated in appropriate atmospheres/temperatures and because of the slower growing nature of Nocardia, the duration of incubation was extended past the customary 48 hours.

This bronchial wash specimen was obtained from an East-Indian gentleman who was experiencing coughing, chest discomfort, dyspnia (shortness of breath) and periodic bouts of haemoptysis (blood in sputum). The gentleman was otherwise healthy, worked as an accountant and had been a resident of Canada for quite some time. No predisposing factors were noted (ie. Immunodeficiency)

Interestingly, within a week we had a second case of somewhat rare Nocardiosis from an Oriental gentleman, the incident unrelated to the first.

In previous years, our lab would have speciated this organism ’in-house’, however with the current state of the economy and subsequent financial challenges, many of the necessary media and reagents necessary for further workup are no longer routinely stocked. Regretfully, in order to cut costs, infrequent or specialized tests are “farmed out” to our local Public Health Laboratory.

Nocardia has worldwide distribution with respiratory infections acquired through inhalation of contaminated dust whereas cutanious/wound infections acquired by traumatic injury. Immunocomprimised individuals are at greater risk of acquiring this opportunistic infection.

Nocardia is a strictly aerobic, catalase positive gram positive bacillus which can form filaments (reminiscent of fungal hyphae) and exhibit branching, The cell wall contains mycolic acids (found in Mycobacteria) which is responsible for a beaded appearance in the gram stain and partial acid-fast staining properties.

Nocardia infections have been shown to respond to treatment with trimethoprim-sulfamethoxazole (Septra), sulphonamides, ceftriaxone, and alizarin)

Below are representative photos of the gram stain, partial acid fast stain, and 5 day growth on NYC agar of the specimen described above. (Click on images to enlarge).

Broncheal Wash Direct Gram Stain
(Showing filamentous, branching gram positive bacilli)

Direct Partial Acid Fast Stain

Dry, Chalky Nocardia Colonies On NYC Agar at 5 Days

Nocardia Wallpaper (1024 X 768) *may be resized by Blogger

1) Partial Acid-Fast staining employed: Carbol fuscin stain (3 min), decolourize with 1% H2SO4 (until colour no longer comes off ~1 min) and counterstain with methyene blue (30 sec).

* * *
New 22/11/10
New 22/11/10 For Comparison (above)
Gram Stain- Nocardia species in Abdominal Abscess 87 yr old male
New 10/11/10-This Nocardia isolate, referred to our Provincial Health Laboratories has been identified as
Nocardia cryiacigeorgica

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