First Report of blaCTX-M-28 in Enterobacteriaceae Isolates in the United Arab Emirates
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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.