| Summary: | Intro: Asymptomatic bacteriuria is a common finding during pregnancy. Effective antibiotic treatment could reduce its adverse effects during pregnancy. However, antimicrobial resistance limits the treatment options. Fosfomycin might be a promising drug in this regard as its resistance is still low. The aim of the study was to assess the MICs of fosfomycin resistant isolates & to investigate the genetic mutations responsible for fosfomycin resistance Methods: This was a 2-year study. Around 10252 urine samples from asymptomatic pregnant females (18-45 years) attending the Antinatal clinics were included in the study. Identification of pathogen & antimicrobial susceptibility testing was done as per standard methods. Fosfomycin resistance was confirmed by agar dilution. Presence of murA, fosA, uhpT & glpT genes were checked by Conventional PCR. Findings: Around 1173 (11.4%) pregnant females were found to have ASB. E. coli 495(42%) being the predominant organism. CRE were 296(40%), MRSA and VRE accounted for 50(66.6%) and 5(2%) respectively. Among oral antibiotics Cotrimoxazole showed (43%), Amoxiclav (6%), Cefixime (37%), Norfloxacin (38%), Nitrofurantoin (60%) susceptibilities while fosfomycin was found sensitive in almost 98% isolates. Only 22 isolates were found resistant to fosfomycin by disc diffusion method. On agar dilution one isolate was found sensitive showing MIC <64μg/ml. Of 21 isolates, fosfomycin MICs were; 256μg/ml (3 E.coli strains), 1024μg/ml (2 E.coli isolates) & rest 16 isolates (5 E.coli, 4 Klebsiella pneumonia, 2 Proteus spp, 2 E.faecalis, 3 Staphylococcus spp) showed MICs >2048μg/ml. On PCR, murA & glpT genes were present in 5& 4GN isolates respectively, while only 1GP isolate was positive for fosA gene. None of the strains showed the amplification of uhpT genes. Conclusion: mur A was commonest genes depicting chromosomal resistance. Fos A was found in only one Enterococcus faecalis indicating transferrable resistance. There was little discrepancy between disk diffusion and agar dilution methods.
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