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Detection of npmA Gene in Enterobacteriaceae Isolated from Clinical Specimens


IM Akuakolam
CN Akujobi
IN Aghanya
SN Ushie
NG Uzoewulu
SN Ukibe
GA Elemuo
AS Ohaegbulem
AS Ezeador
AE Okoro

Abstract

Background: Antimicrobial resistance has become of utmost concern to the global public health and the emergence of high-level aminoglycoside resistance has threatened the synergistic use of β-lactam and aminoglycoside antibiotics in the treatment of infections, especially those due to Gram-negative bacteria, thus resulting in increasing morbidity and mortality, as well as treatment cost. The aim of the study was to determine the presence of high-level aminoglycoside resistance npmA gene in Enterobacteriaceae isolates recovered from clinical specimens in a tertiary hospital.


Methods: A total of 419 non-duplicate bacteria isolated from clinical specimens were screened for Enterobacteriaceae using the Microbact 12A Gram negative bacilli semi-automated identification system. Antimicrobial susceptibility tests were performed on the Enterobacteriaceae isolates using commercially available gentamicin antibiotic discs. Gentamicin (120µg) was used for phenotypic confirmation of high-level aminoglycoside resistance. All the resistant isolates were examined for the presence of npmA gene using conventional polymerase chain reaction.


Results: Out of the 419 isolates 250 (60.1%) were confirmed Enterobacteriaceae, 30.4% (76/250) were resistant to 30µg of gentamicin, while 4% (10/250) of the Enterobacteriaceae isolated were resistant to 120µg gentamicin. However, the npmA gene was not detected in any of the high-level aminoglycoside resistant isolates.


Conclusion: Despite the phenotypic prevalence of high-level aminoglycoside resistance observed in the Enterobacteriaceae isolates, the npmA gene was not detected. The absence of the npmA gene therefore suggests that other factors may be responsible for the phenotypic high level aminoglycoside resistance recorded in this study.


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eISSN: 2536-6718
print ISSN: 2141-162X