Interstitial pulmonary inflammation due to Microbacterium sp. after heart transplantation

Abstract

A coryneform bacterium was isolated from the bronchoalveolar aspirate of a patient with interstitial pulmonary inflammation. Commercial systems identified the isolate as Corynebacterium sp. or Aureobacterium sp./Corynebacterium aquaticum, but 16S rRNA gene analysis unequivocally attributed it to the genus Microbacterium. This represents the first documented case of Microbacterium pulmonary infection. Case reportA 44-year-old man underwent heart transplantation on 8 August 2000 as a consequence of ischaemic cardiomyopathy (previous extended anterior myocardial infarction). Transplantation and the post-operative course were uncomplicated and the patient was discharged on 31 August 2000 and prescribed a cyclosporin A, azathioprine and corticosteroid therapy (cyclosporin blood levels were expected to be 400 ng dl 21 ). Ten days later, the patient showed an acute organ rejection documented by endomyocardial biopsy (Grade 2, Dallas Classification, with diffuse and aggressive infiltrate) and was treated with high doses of intravenous corticosteroid (500 mg methylprednisolone per day for 3 days). Following this therapy, the rejection successfully reversed (Grade 1A at 1 month after treatment).Twelve days after corticosteroid treatment, the patient was readmitted with fever, neck pain, oesophageal discomfort during deglutition and a cough. At that time, the white blood cell count was 0?56 cells ml 21 with 80 % neutrophils, 15 % lymphocytes and a CD4/CD8 ratio of 0?4, thus showing intense immunosuppression. Fever quickly rose to 38?3 u C. Several blood and sputum cultures were negative for aerobic and anaerobic bacteria and for fungal cells. Before and after the transplant, the patient had been monitored for cytomegalovirus by the pp65 antigenaemia test, whose results were constantly negative. At the time of readmission, a further test for cytomegalovirus pp65 antigenaemia was performed and the result again was negative. A chest radiograph showed interstitial inflammation of the inferior left pulmonary lobe. After a few days, pleural effusion developed, as evidenced by physical examination. Computerized axial tomography examination confirmed pulmonary inflammation and pleural effusion, but excluded mediastine involvement. Initially, the patient was treated empirically with meropenem (500 mg three times per day), clarithromycin (500 mg per day), ciprofloxacin (200 mg twice a day) and fluconazole (150 mg per day), all intravenously, and oral trimethoprim/sulfamethoxazole (800 mg per day). This therapy did not lower the fever, nor did it attenuate the other symptoms. After 5 days, a selective bronchoalveolar washing was performed and the aspirate was examined. Direct Gram staining showed the presence of Gram-positive bacilli, whilst observation for Pneumocystis jiroveci (Pneumocystis carinii) after Giemsa and toluidine blue O staining yielded negative results. The aspirate was not checked for the presence of cytomegalovirus, but was cultured for aerobic and anaerobic bacteria, as well as for fungi. Culture on blood agar and ...

Identities of Microbacterium spp. Encountered in Human Clinical Specimens

“…Despite this large number of species, only in the mid1990s was the presence of microbacteria in human clinical specimens recognized (7,8,11). Since then, only eight other reports on microbacteria have appeared in the relevant clinical microbiology literature (1,2,9,(12)(13)(14)(15)(16). The aim of the present study was to reveal the distribution of individual Microbacterium species in human clinical specimens by applying phenotypic and molecular genetic methods.…”

Catheter-associated bloodstream infection caused by Leifsonia aquatica in a haemodialysis patient: a case report

“…In the present case, the commonly used API Coryne system was inconclusive and identification was confirmed by molecular methods (16S rRNA gene sequencing). Limitations of the API Coryne system in the identification of L. aquatica and related species have been reported previously (Winn et al, 2006;Lau et al, 2002;Saweljew et al, 1996;Giammanco et al, 2006). Another study including 178 clinical isolates of Gram-positive rods revealed that 25 % of the strains required additional tests for their identification and 9 % were incorrectly classified (Almuzara et al, 2006).…”

A selective medium for the isolation of Microbacterium species in oral cavities

“…In spite of the large number of species, few studies have been published on Microbacterium species in the relevant clinical microbiology literature. Microbacterium species, except for Microbacterium resistens, Microbacterium hominis, Microbacterium paraoxydans, and Microbacterium binotii, were initially defined by strains that originated from the environment, and only a small number of species were found to be the causative agents of infections, not only for sporadic infections, but also for nosocomial outbreaks of bacteremia caused by Microbacterium species (Adderson et al, 2008;Alonso-Echanove et al, 2001;Funke et al, 1998;Giammanco et al, 2006;Hirji et al, 2003). Outbreaks of Microbacterium species among cancer patients have indicated their potential to cause morbidity and mortality in immunocompromised patients, suggesting the potential for nosocomial dissemination (Alonso-Echanove et al, 2001).…”