Community prevalence of carbapenemase-producing Gram-negative bacteria

Purpose: To raise awareness of carbapenemase-producing organisms, identify “at-risk” patients when admitted in a medical healthcare facility, and to outline effective infection prevention and control measures in order to halt the entry and spread of these organisms. Methods: A total of 1043 un-duplicated urine specimens of healthy volunteers who had no travel history or history of hospitalization were screened. The carbapenemase genotype of each imipenem-resistant strain was determined. Molecular typing and homology analysis of the main carbapenemase-producing strains were used to reveal the mode of transmission of resistance genes. Through transfer joint experiments, the potential risk of spread of carbapenemase genes was assessed. Results: A total of 19 carbapenemase-producing strains from 1,043 non-duplicated healthy volunteers (1.82 %) were identified. The main carbapenemase-producing organism was E. coli (42.1 %, 8/19). The main carbapenemase genotype of E. coli was blaKPC-2 (7 strains). Results from multi-locus sequence typing (MLST) indicated that 7 E. coli isolates belonged to ST-10, ST-101, ST-131, ST-405, ST-410 and ST-1193 and ST-2562. Homologous cluster analysis revealed that the sequence types among the 7 E. coli were high in diversity. The blaKPC-2 gene was successfully transferred from these isolates to 10.22-14 via conjugation. All recipient cells showed marked decreases in carbapenem sensitivity to imipenem (p < 0.05)). The degrees of conjugation were 2.10±0.12 ×10-4, 1.96±0.14×10-4, 2.72±0.18 ×10-4, 3.15±0.20 × 10-4, 2.92±0.23 ×10-4, 3.50±0.20 ×10-4 and 4.12±0.24 ×10-4 in recipient cells of TC7.23-51, TC8.9-42, TC8.15-11, TC8.23-59-3, TC8.23-83, TC9.08-47 and TC10.13-15, respectively. Conclusion: The findings demonstrate the pattern and features of carbapenemase-insensitive E. coli. The blaKPC-2 was the main community-prevalent gene of carbapenem-resistant E. coli. In view of increasing incidence of resistance to multi-drug therapy, surveillance of insensitivity to antibiotics is vital, especially urinary system infection due to carbapenem-insensitive E. coli.