Corynebacterium species isolated from patients with mastitis.

Corynebacteria were isolated from breast tissue, pus, or deep wound swabs of 24 women; the most common species isolated was the newly described Corynebacterium kroppenstedtii, followed by Corynebacterium amycolatum and Corynebacterium tuberculostearicum. Gram-positive bacilli were seen in samples sent for culture or in histological specimens for 12 women, and 9 of the 12 women from whom adequate histological specimens were obtained had conditions that met the criteria for granulomatous lobular mastitis, a chronic inflammatory disease of unknown etiology.

A clinicopathological review of 34 cases of inflammatory breast disease showing an association between corynebacteria infection and granulomatous mastitis.

AIM: Granulomatous mastitis is a rare condition of unknown aetiology. The great majority of cases has not been associated with bacterial pathogens if women with mammary tuberculosis are excluded. We noted that some women in Auckland with a histological diagnosis of granulomatous mastitis had both microbiological and histological evidence of corynebacteria infection and aimed to study this further. METHODS: Thirty-four women were reviewed who presented with inflammatory breast disease and had microbiological specimens from which corynebacteria were isolated and/or histological specimens containing coryneform bacteria. These 34 cases were compared with 28 controls with similar histology but no evidence of corynebacteria infection. RESULTS: Twenty-seven (79%) of the cases and 21 (75%) of the controls had histological and/or cytological evidence of suppurative granulomas. Fourteen of the 34 cases also had Gram-positive bacilli (GPB), recognisable as coryneform bacteria, in histological sections. In all cases the bacilli were confined to empty spaces, consistent with dissolved lipid, and were surrounded by neutrophils and, frequently, suppurative granulomas. Corynebacterium species were isolated from 52 of 116 microbiological specimens taken from the 34 cases. Forty of these 52 cultures were pure. Twenty-four of the cultures were further classified biochemically and using 16S rRNA gene sequencing. Twenty of the 24 were lipophilic Corynebacterium species and 14 were identified as Corynebacterium kroppenstedtii. The cases were more likely to present with fever or neutrophilia and more often formed sinuses than the controls but other clinical features were similar. Maori and Pacific Islanders accounted for 77% of the women across both groups. CONCLUSION: We suggest granulomatous mastitis can be associated with corynebacteria infection, particularly infection by C. kroppenstedtii. The significance of this finding, which has previously been described in only a single case report, is discussed.

Anaerobic bacteraemia in patients admitted to Auckland City Hospital: its clinical significance.

AIM: To determine the clinical significance and outcomes for patients with anaerobic bacteraemia at our institution over a 2-year period. METHOD: The isolates were identified from the laboratory database and patient information obtained from clinical records. RESULTS: Anaerobes were isolated from 140 blood culture sets taken from 114 patients. For 59 patients, the isolates were considered to be contaminants. Of note, all Propionibacterium spp. were considered contaminants. For the patients with true bacteraemias, the most likely source of infection was intra-abdominal, 26 (50%), mucositis associated with neutropaenia contributed to by cytotoxic therapy, 11 (19%), skin and soft tissue, 4 (8%), pelvic, 5 (9%) and oropharyngeal, 4 (8%). Thirty-five patients were on appropriate therapy prior to the availability culture results. Five patients died but only one death was directly attributable to anaerobic bacteraemia. CONCLUSION: At our institution, anaerobes accounted for 2.3% of all positive blood cultures. Excluding Propionibacterium spp., most isolates were considered clinically significant. The most common source for the bacteraemia was intra-abdominal infection, followed by mucositis in neutropaenic patients. Empiric antimicrobial therapy provided appropriate cover for two-thirds of the patients. One death was directly attributable to anaerobic bacteraemia.