Supplementary Material for: Evidence of Interruption of the comM Gene in a Large Series of Clinical Isolates of Multidrug-Resistant Acinetobacter baumannii

<p>Recent studies have recognized the ATPase-encoding <i>comM</i> gene as a hot spot for the integration of <i>Acinetobacter baumannii</i> resistance islands (RIs). Despite the circulation of high numbers of multidrug-resistant <i>A. baumannii </i>(MDR-AB) isolates in Middle East countries, no information is available about the interruption of <i>comM</i> and subsequent transposition into <i>comM</i> in isolates belonging to the global clones (GC) GC1, GC2, or GC3. In this study 401 <i>A. baumannii</i> isolates from hospitals in Tehran, Iran, were included. The resistance profile was determined by disc diffusion against 22 antibiotics. PCR was used to assess the GC type, presence of the <i>comM</i> gene, and the boundary junctions (J1 and J2) of RIs. Most of the MDR-AB isolates (384 of 388; 98%) and more than half of the susceptible <i>A. baumannii </i>isolates (9 of 13; 69%) had interrupted <i>comM</i> gene-carrying integrative elements. Among the isolates tested, 57 belonged to GC1, 86 to GC2, and 8 to GC3. A set of 250 isolates showed distinct patterns of allele-specific PCR for <i>ompA</i>, <i>csuE</i>, and <i>bla</i><sub>OXA-51-like</sub> genes. All but 2 of the GC1 isolates and 2 of the GC2 isolates contained interrupted <i>comM</i> genes. Four <i>A. baumannii</i> isolates harbored intact <i>comM</i>, but were multiply resistant to antibiotics. This study demonstrated that the <i>comM</i> gene is targeted by transposons in Iranian MDR-AB isolates belonging to different GCs. The data also showed that the carriage of interrupted <i>comM</i> is not exclusive to MDR isolates of <i>A. baumannii</i>.</p>