Leuconostoc pseudomesenteroides as a Cause of Nosocomial Urinary Tract Infections

Leuconostoc pseudomesenteroides as a Cause of Nosocomial Urinary Tract Infections,ELISABETE A. CAPPELLI,ROSANA R. BARROS,THEREZA CRISTINA F. CAMELLO,L

Leuconostoc pseudomesenteroides as a Cause of Nosocomial Urinary Tract Infections   (Citations: 13)
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The phenotypic and genotypic characterization of five clinical isolates of Leuconostoc pseudomesenteroides associated with nosocomially acquired urinary tract infections is described. All the strains were susceptible to chloramphenicol, clindamycin, erythromycin, gentamicin, and tetracycline; all were resistant to nalidixic acid, norfloxacin, and vancomycin; and all were intermediately affected by ampicillin and penicillin. Analysis of chromosomal DNA by pulsed-field gel electrophoresis after treatment with SmaI indicated a clonal relationship of the isolates. The results provide evidence for the possibility of nosocomial transmission of this unusual opportunistic, vancomycin-resistant pathogen. The genus Leuconostoc is composed by catalase-negative gram-positive microorganisms with irregular coccoid morphol- ogy. These organisms may be misidentified as Lactobacillus, Streptococcus (particularly the viridans group), Pediococcus ,o r even Enterococcus, as all share several biochemical properties (3, 20). Unlike most other gram-positive bacteria, these micro- organisms have an important physiological marker related to their intrinsic resistance to vancomycin (6, 18). Before 1985, Leuconostoc species were usually considered nonpathogenic and, therefore, of little or no importance in clinical microbiol- ogy (3, 19). Since then, increasing numbers of infections due to Leuconostoc have been reported (1, 2, 8-12, 23). Despite re- maining uncommon, these pathogens are gaining importance as opportunistic agents of human infections associated with high mortality rates, mainly bacteremia (14, 15, 18). Infections due to Leuconostoc occur more frequently in patients being treated for underlying diseases with vancomycin therapy (7, 13), although Leuconostoc infections have also been document- ed in otherwise healthy patients (4). The present study de- scribes the phenotypic and genotypic characterization of a clus- ter of five Leuconostoc pseudomesenteroides strains recovered from hospitalized patients with symptomatic urinary tract in- fections, providing evidence for the possible nosocomial trans- mission of this opportunistic vancomycin-resistant bacterium. Five clinical isolates of catalase-negative, vancomycin-resis- tant, gram-positive cocci recovered from urine specimens ob- tained from five inpatients admitted to a University Hospital in Rio de Janeiro, Brazil, were studied. The strains were isolated within a period of 1 week (in April 1997) from patients in two units (nephrology and urology) located on the same hospital floor. Clinical manifestations of the infections included dysuria and/or fever, and the microorganisms grew in pure cultures. All five patients had been admitted to the hospital due to other medical conditions, and only one of the patients had a urinary catheter at the time the culture-positive urine was collected. The most common risk factors associated with infection acqui- sition are described in Table 1. Identification of the strains to the genus level was performed as described elsewhere (6) by using tests for detecting the following physiological characteristics: presence of catalase, pyrrolidonyl arylamidase and leucine aminopeptidase activi- ties, hydrolysis of esculin in the presence of bile, growth in the presence of 6.5% NaCl, vancomycin susceptibility, and produc- tion of gas in lactobacilli De Mann, Rogosa, and Sharp (MRS; Difco Laboratories, Detroit, Mich.) broth. Additional physio- logical tests, including production of acids from arabinose, lactose, maltose, melibiose, salicin, sucrose, threalose, and xy- lose, were used for the characterization of the isolates to the species level. All five clinical isolates had similar physiological characteristics. They were negative for catalase, pyrrolidonyl
Published in 1999.
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