Abstract
OBJECTIVE: The aim of this study was to retrospectively characterize E. coli and K. pneumoniae isolates obtained from neonates during a suspected NICU outbreak of infection in Ha'il, Saudi Arabia during a period of one month (April 2014). METHODS: Antibiotic susceptibility patterns, molecular characterization for antibiotic-resistant genes (blaTEM, blaSHV, and blaCTX-M), and genotyping by PFGE and MLST were performed. RESULTS: A total of 24 E. coli and 48 K. pneumoniae isolates were cultured from neonates that had been admitted to the NICU. Among E. coli, the majority of isolates (19/24) were ESBL-positive and all of these nineteen (100%) harbored the CTX-M-15 gene. A total of 15% (3/19) were co-producers of CTX-M-15 and SHV-12, and 68.4% (13/19) were co-producers of CTX-M-15 and TEM-1. Among K. pneumoniae isolates, 87.5% (42/48) were ESBL positive with 92.85% (39/42) of these isolates containing the CTX-M-15 gene. A total of 97% (38/39) of K. pneumoniae were co-producers of CTX-M-15 and SHV-12, and 88% (37/42) were positive for TEM-1. Furthermore, 85.7% (36/42) K. pneumoniae were co-producers of CTX-M-15 and TEM-1. The majority of E. coli isolates (18/19 isolates) were grouped into two genetic clusters by pulsed field gel electrophoresis (PFGE) and all the isolates were found to be ST-131 type. In contrast, K. pneumoniae (31/42) isolates belonged to a single genotypic lineage, and all (100%) isolates belonged to the ST-14 type. CONCLUSION: This is the first report of CTX-M-15-positive, ESBL E. coli, and K. pneumoniae isolates recovered from an outbreak in an NICU in Ha'il, Saudi Arabia. It is alarming to note the high rate of outbreak isolates with simultaneous production of CTX-M-15 and SHV-12 conferring high-level resistance to oxyimino-cephalosporins.