Enigmatic Leuconostoc and Lactobacillus infections

Abstract number: 1134_04_54

Kulwichit W., Nilgate S., Krajiw S., Srisawat N., Unhasuta C., Chongthaleong A.

Objectives:  

Leuconostoc and Lactobacillus are gram positive coccobacilli of low virulence. Human infections are commonly misdiagnosed. This report is to provide interesting diagnostic and clinical features of these organisms.

Methods:  

26 clinical isolates identified as Leuconostoc by API 20 STREP (Biomérieux, Inc.) in our hospital during 1997–2004 were reevaluated by repeated API 20 STREP, API 50 CHL, conventional phenotypic assays including gas production in MRS broth and vancomycin MIC, and two genus-specific PCRs for Leuconostoc and Lactobacillus as previously described (Lett Appl Microbiol 2000;31:129–33 and FEMS Microbiol Lett 2002;214:271–5, respectively). Four ATCC strains of Leuconostoc, Lactobacillus, and Pediococcus were used as controls in all experiments. A review of medical records was performed only in cases with confirmed both phenotypic and PCR assays to be Leuconostoc or Lactobacillus.

Results:  

Only 3 isolates initially identified as Leuconostoc were confirmed by both manual phenotypic and PCR assays. Another two turned out to be Lactobacillus spp. The rest were mostly Streptococci or closely related bacteria. API 50 CHL identified 16 isolates as Lactobacillus spp., only 2 of which were confirmed by genus-specific PCR. Lactobacillus pentosus ATCC 8041 and Pediococcus pentosaceus ATCC 33316 were both identified by API 20 STREP as Leuconostoc and by API 50 CHL as Lactococcus lactis ssp lactis 1 and Lactobacillus pentosus, respectively. Clinical features are diverse and include both community and hospital acquired infections in normal and compromised hosts without antibiotic pressure, and with various outcomes (Table).

Conclusions:  

These bacteria are underrecognized emerging pathogens which are frequently misidentified. Without confirmation by manual phenotypic and genotypic assays, widely-used commercial could potentially mislead clinical management and reports in medical literature.