Background: The CTX-M family of extended-spectrum beta lactamase (ESBL) enzymes is comprised of over 60 blaCTX-M gene variants with the predominance of blaCTX-M-15 in many regions. In this report, we present the first description of blaCTX-M-28 in the United Arab Emirates.
Methods: Forty-five non-duplicate ESBL producing isolates identified in a secondary care facility in the United Arab Emirates from June to July 2016 were studied. Gene sequencing was performed and DNA sequences were annotated using the BLAST program to identify the gene subtypes.
Results: The majority of the ESBL positive isolates were E. coli (n/N = 39/45; 86.6%) followed by K. pneumoniae (n = 5) and K. oxytoca (n = 1). All isolates harboured blaCTX-M and blaTEM genes, 18 had blaSHV, and 2 were blaVIM positive. Thirty-seven isolates (82.2%) were positive for blaCTX-M-28. Other blaCTX-M genes identified include blaCTX-M-167 (n = 2; isolates #1 and 26) and one each for blaCTX-M-38, blaCTX-M-163, and blaCTX-M-198. No blaCTX-M-15 was identified. The predominant blaTEM subtype was blaTEM-171 (n = 8) followed by one of each of blaTEM-120, blaTEM-163, and blaTEM-206. The blaSHV subtypes were blaSHV-148 and blaSHV-187.
Conclusion: The findings indicate the first description of blaCTX-M-28 in a setting where blaCTX-M-15 was previously predominant.