AUTHOR=Villalón Pilar , Ortega Montserrat , Sáez-Nieto Juan A. , Carrasco Gema , Medina-Pascual María J. , Garrido Noelia , Valdezate Sylvia 

TITLE=Dynamics of a Sporadic Nosocomial Acinetobacter calcoaceticus – Acinetobacter baumannii Complex Population

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.00593

DOI=10.3389/fmicb.2019.00593

ISSN=1664-302X

ABSTRACT=<p>Our objective was to improve current knowledge of sporadic (Spo) nosocomial <italic>Acinetobacter</italic><italic>calcoaceticus-Acinetobacter baumannii</italic> (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 <italic>gyr</italic>B-PCR, and via <italic>gyr</italic>B- and <italic>rpo</italic>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. <italic>A. baumannii</italic> was the most common (67/101 PFGE types), followed by <italic>Acinetobacter pittii</italic> (22/101), <italic>Acinetobacter lactucae</italic> (6/101), and <italic>Acinetobacter calcoaceticus</italic> (2/101). <italic>gyr</italic>B, <italic>rpo</italic>B1, and <italic>rpo</italic>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<italic>Aba2</italic>-<italic>bla</italic><sub>OXA-58-like</sub>-IS<italic>Aba3</italic>, and 2/101 were multidrug-resistant. It can be concluded that the examined Spo Acb complex population was mainly composed of <italic>A. baumannii</italic>. 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 <italic>A. baumannii</italic> clones -ST2, ST3, ST15, and ST80-.</p>