Journal of Gastrointestinal & Digestive System
Open Access

Abstract

In the present study, low abundance of NarG and NarH, two components of respiratory nitrate reductase (Nar), in streptomycin (SM)-, gentamycine (GEN)-, ceftazidime (CAZ)-, tetracycline (TET)- and nalidixic acid (NA)-resistant Escherichia coli strains using Native/SDS-PAGE based proteomics were characterized. The findings using Western blotting and Native/SDSPAGE upon genetically deleted mutants of NarG and NarH were validated. However, further functional evidence indicates that loss of narG and narH results in two types of growth behaviors, higher and lower than control, in antibiotic-resistant E. coli strains. Specifically, SM-, GEN- and CAZ-resistant bacteria grow faster, whereas NA- and TET-resistant E. coli strains grow slower. Thr data indicate that down-regulation of respiratory Nar is essential for E. coli in resistance to aminoglycoside and cephalosporin antibiotics since SM, GEN and CAZ belong to the classes of drugs, respectively. Meanwhile, the results show that differential mechanisms exist in different antibiotic-resistant bacteria. The reason why the reversal growths are detected in NA- and TET-resistant E. coli strains waits investigation. Our findings serve to propose novel strategies for controlling of aminoglycoside- and cephalosporin-resistant E. coli strains through elevation of respiratory Nar activity.

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