Urinary Mycobacterium fortuitum infection

Culture positivity of smear negative pulmonary and extrapulmonary tuberculosis- A study from North Kerala, India

Introduction:

The identification of smear negative pulmonary and extrapulmonary tuberculosis continues to remain a diagnostic challenge. This study was conducted in a tertiary care setup in north Kerala to isolate and identify mycobacteria by culture from radiologically and clinically suspected cases of smear negative pulmonary and extrapulmonary tuberculosis.

Methods:

A total of 200 samples (100 pulmonary and 100 extrapulmonary) were processed and cultured by automated (MB/BacT) and conventional methods. Heat stable catalase test, nitrate reduction test and detection of MPT 64 antigen were done to aid species identification.

Results:

Overall culture positivity was 7% (14 isolates - 8 pulmonary and 6 extrapulmonary) of which 92.9% (13) of the isolates were Mycobacterium tuberculosis and 7.1% (1) was Mycobacterium fortuitum (identified by molecular typing). Detection rate by automated method was 7% (14) and by conventional method was only 1.5% (3).

Conclusion:

Despite its shortcomings and low positivity, culture still remains the gold standard for the diagnosis of EPTB and SNPT. However, automated liquid cultures have better isolation rates than the conventional LJ culture. Subjecting these isolates to rapid diagnostic tests like antigen detection and LPA can aid in the early institution of appropriate treatment regimen.

Unusual clinical presentation of Mycobacterium fortuitum infection in an immunocompetent woman

The Mycobacterium fortuitum group of rapidly growing nontuberculous mycobacteria is an uncommon cause of renal infection, particularly in otherwise healthy hosts. We describe a case of nephritis due to M. fortuitum in an immunocompetent woman with a clinical and radiological diagnosis of renal tuberculosis.

Mycobacterium fortuitum complex in Sweden during an 11-year period

Records of patients have been retrospectively examined studied during an 11-y period, from whom Mycobacterium fortuitum or M. chelonae was isolated in Sweden. Respiratory isolates were obtained from 71 patients. Clinical information was accessible in 52, chest X-ray was pathological in 51, and 42 had underlying diseases. Four skin and 4 urine isolates were observed. Two cases of osteitis and 2 bone marrow isolates of M. chelonae were found. One girl had a submandibular lymph node abscess with M. fortuitum. Of 2 HIV patients, 1 had positive blood cultures with M. fortuitum and the other positive sputum culture with M. chelonae. The broad spectrum of infections with M. fortuitum complex necessitates an integrated judgement of clinical and bacteriological data to determine the relevance of such isolates.

Intracellular Antimycobacterial Activity of Ciprofloxacin and Ofloxacin in Mycobacterium Fortuitum Infected Human Polymorphonuclear Leucocytes

The broadspectrum quinolone antibiotics ciprofloxacin and ofloxacin were tested for activity against the atypical mycobacterium M.fortuitum. In vitro minimal inhibitory concentrations (MIC) were done in Brain Heart Infusion broth and intracellular determinations in Medium 199 cell culture medium. The PMNs with intracellular bacteria and controls with or without drugs were incubated for six hours at 37°C. Hourly, 0.1 ml aliquotes were taken for colony forming units (cfu) assays. In vitro and intracellular MIC's for ciprofloxacin were 0.125mg/l and 0.625 mg/l respectively, while for ofloxacin they were 0.2mg/l and 0.4 mg/l, respectively.

Control of intracellular growth of Mycobacterium fortuitum by human monocytes in vitro

The ability of human monocytes to phagocytize and respond to infection by Mycobacterium fortuitum was tested using the method of Crowle and May. The monocytes were obtained from heparinized donor blood samples and separated from lymphocytes by adherence to plastic surfaces. M. fortuitum infection was performed immediately. Intracellular viability was indicated by colony forming units (CFU) done at 2 hour intervals. Monocytes were found to cause a rapid reduction in CFU during the first 2 hours of incubation. The rate of killing of M. fortuitum decreased thereafter but continued for the entire 8-hour study period. In parallel tests, ciprofloxacin and ofloxacin were added to the culture medium. Increased intracellular killing was observed with drug concentrations above 2 x MIC in both cases. Ofloxacin showed better antimycobacterial effects than ciprofloxacin.

A case of prolonged urinary tract infection caused by Mycobacterium fortuitum

A case of prolonged urinary tract infection caused by Mycobacterium fortuitum in a 56-year old female patient is reported. The infection, which was resistant to therapy with conventional antituberculous agents, responded well to a combination of trimethoprim, sulfamethoxazole and doxycycline.