Detection of CTX-M groups using PCR
All CTX-M positive MDR E. coli isolates (n=86) were further tested for the detection of major CTX-M groups, i.e., blaCTX-M-1, blaCTX-M-2, blaCTX-M-8, blaCTX-M-9, and blaCTX-M-25, using a multiplex PCR approach. blaCTX-M-1 was the most common group (87%), followed by blaCTX-M-9 (16.27%) were found in CTX-M positive E. coli isolates. Both blaCTX-M-2 and blaCTX-M-8/25 groups were absent. Further sequence analysis of CTX-M genotypes showed that blaCTX-M-28 was predominant allele, which was carried by 33 (38.37%) isolates, followed by blaCTX-M-14 (n=15, 17.44%), blaCTX-M-66 (n=12, 13.95%), blaCTX-M-55 (n=9, 10.46%), blaCTX-M-69 (n=6, 6.97%), blaCTX-M-15 (n=4, 4.65%), blaCTX-M-177 (n=4, 4.65%), and blaCTX-M-148 (n=3, 3.48%). Figure 2B shows the frequency (%) of various ESBL-encoding genes among 86 positive CTX-M E. coli isolates.