Dynamics of a Sporadic Nosocomial Complex Population.

Our objective was to improve current knowledge of sporadic (Spo) nosocomial (Acb) complex populations, and thus better understand the epidemiology of Spo and endemoepidemic (EE) strains. Between 1999 and 2010, 133 isolates of Spo Acb complex were obtained from a single hospital. Species were identified by B-PCR, and via B- and B-sequencing. Clonal analysis was undertaken using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing. Susceptibility to antimicrobial agents was determined by microdilution and E-tests. Carbapenemase genes were detected by PCR. One hundred and one PFGE types were detected. was the most common (67/101 PFGE types), followed by (22/101), (6/101), and (2/101). B, B1, and B2 sequencing returned 49, 13, and 16 novel sequences, respectively. Sixty-three sequence types (STs) (38 new STs and 66 new alleles) were detected; the most common were ST2 (29/133 isolates) and ST132 (14/133). Twenty-six OXA-51 allelic variants were detected, nine of which were novel. The PFGE types were generally susceptible (88/101) to all the tested antimicrobials; 3/101 were carbapenem-resistant due to the presence of the genetic structure IS- -IS, and 2/101 were multidrug-resistant. It can be concluded that the examined Spo Acb complex population was mainly composed of . Many different clones were detected (with ST2 clearly dominant), all largely susceptible to antimicrobials; multidrug resistance was rare. In contrast, a previously examined EE Acb population was composed of just four expanding, multidrug-resistant clones -ST2, ST3, ST15, and ST80-.