A-254 Molecular characterization of carbapenem and colistin resistance in isolates causing UTI at an outpatient setting of a tertiary care hospital

Abstract Background Increasing resistance to higher end antibiotics like carbapenems and colistin is a great cause of concern. There is a paucity of data on the detection of carbapenem and colistin in outpatient settings. This study was to determine prevalence of Carbapenem Resistant Enterobacterales (CRE) and colistin resistance in CRE, at the outpatient setting of tertiary care institute of North India. Methods This prospective observational study conducted over 12 months of study (1st January 2020 - 31st December 2020). A total of 6829 urine non-repetitive samples were received from various OPDs of our institute. Urine culture was performed using a semi-quantitative technique on cysteine lactose electrolyte deficient medium (CLED agar, Hi-Media, India). Antibiotic sensitivity was put up by the Kirby Bauer disc diffusion method on Mueller Hinton agar (MHA) (Hi-Media India) adhering to the clinical laboratory standards institute (CLSI) guidelines. Isolates found to be carbapenem-resistant were also identified by VITEK MS MALDI-TOF Mass Spectrometer (bioMérieux), and in them antimicrobial susceptibility was performed by Vitek-2 (bioMe´rieux, Inc Hazelwood, MO). Those resistant to resistant to carbapenems were subjected for colistin resistance by BMD method. Results A total of 669/6829 (9.79%) urine specimens yielded significant growth mostly in females (54.1%), lesser than other studies probably due to less samples received because of COVID-19 pandemic. The majority (50.82 %) of patients belonged to the early adult group (15-45 years). The majority of organisms were Enterobacteriaceae (509/669,76.08%). The most common organism isolated was E.coli (56.5%) followed by K.pneumoniae (18.2%). 5.97% (40/669) isolates were carbapenem-resistant. 6.87% (35/509) of Enterobacteriace were carbapenem-resistant, which is lesser than other studies possibly due to samples form outpatient settings. blaNDM(18/35), blaKPC(2/35), blaOXA(11/35) and blaOXA-48(5/35). Some isolates had co-existence of > 2 carbapenemase genes with NDM, OXA and OXA-48. Colistin resistance in CRE was 11% (Figure 6) which is like other studies conducted in same tertiary centre. Comparison of resistance of pattern of other antibiotics in CRE and Carbapenem Sensitive Enterobacterales (CSE) group done for prevalence. Conclusion The presence of these genes in outpatient settings is worrisome. Both blaNDM-1 and blaOXA-48 resulted in higher MICs against carbapenems. Co-presence of NDM-1 with OXA-48 producing E. coli in urine culture. Colistin resistance in outpatient setting is alarming. Early detection of these resistant determinant genes by molecular methods is essential in limiting the spread of infection due to these organisms.