First Emergence of NDM-5 and OqxAB Efflux Pumps Among Multidrug-Resistant Klebsiella pneumoniae Isolated from Pediatric Patients in Assiut, Egypt

INTRODUCTION: New Delhi metallo-β-lactamase (NDM)-producing K. pneumoniae poses a high risk, especially among Egyptian pediatric patients who consume carbapenems antibiotics very widely and without adequate diagnostic sources. In addition, presence of efflux pump genes such as OqxAB increases resistance against many groups of antimicrobials which exacerbates the problem faced for human health. This study aimed to determine NDM variants among K. pneumoniae strains isolated from pediatric patients in Egypt, analyze the presence of OqxAB genes, and molecular characterization of bla(NDM-5)-positive K. pneumoniae. METHODS: Fifty-six K. pneumoniae isolates were recovered from pediatric patients, and tested for carbapenemase by modified carbapenem inactivation methods (mCIM) test. Minimum inhibitory concentrations of meropenem and colistin were determined by meropenem E-test strips and broth microdilution, respectively. PCR was used for the detection of the resistant genes (ESBL gene (bla(CTX-M)), carbapenemase genes (bla(NDM), bla(KPC)) colistin resistant (mcr1, mcr2)) and genes for efflux pump (oqxA and oqxB). Bla(NDM) was sequenced. The effect of efflux pump in NDM-5-producing isolates was assessed by measuring MIC of ciprofloxacin and meropenem before and after exposure to the carbonyl cyanide 3-chlorophenylhydrazone (CCCP). The horizontal gene transfer ability of bla(NDM-5) was determined using liquid mating assay and PCR-based replicon typing (PBRT) was done to determine the major plasmid incompatibility group. RESULTS: Twenty-nine isolates were positive for bla(NDM-1), nine isolates were positive for bla(NDM-5), and 15 isolates were positive for bla(KPC). There is a significant increase of meropenem MIC of NDM-5-positive isolates compared with NDM-1-positive isolates. In addition, 38 isolates were positive for CTX-M, and 15 isolates were positive for mcr1. Both OqxA and OqxB were detected in 26 isolates and 13 isolates were positive for OqxA while 11 isolates were positive for OqxB only. All NDM-5-producing isolates except one isolate could transfer their plasmids by conjugation to their corresponding transconjugants (E. coli J53). Plasmid replicon typing showed that FII was predominant in NDM-5-producing K. pneumoniae. Similar strains were found between the three isolates and similarity was also detected between the two isolates. CONCLUSION: The highly resistant K. pneumoniae producing bla(NDM-5) type was firstly isolated from pediatric patients. The association of efflux pump genes such as OqxAB is involved in resistance to ciprofloxacin. This highlighted the severity risk of bla(NDM-5)-positive K. pneumonia as it could transfer bla(NDM-5) to other bacteria and has more resistance against carbapenems. This underlines the importance of continuous monitoring of infection control guidelines, and the urgent need for a national antimicrobial stewardship plan in Egyptian hospitals.