Background and study aim: Carbapenemase-producing gram-negative bacteria are widely distributed in hospitals and cause nosocomial infections with high mortality rates. The current study aimed to assess the diagnostic performance of the Carba NP strip test versus tube method, and to determine the frequency of carbapenemase genes‎‎.
Materials and Methods: In this prospective study, we performed the Carba NP strip test and Carba NP tube method in hundred gram-negative isolates (60 Klebsiella pneumoniae, 26 Pseudomonas, and 14 E.coli). We detected bla_KPC, bla_VIM, bla_OXA-48, bla_GES, and bla_IMP genes by the Real-time PCR.
Results: Out of the 80 meropenem-resistant isolates, bla_VIM (66/80, 82.5%), followed by the bla_OXA-48 gene (60/80, 75%), were the most prevalent gene, whether as a single gene or coexpressed with other genes. One hundred percent of the Klebsiella pneumoniae and E.coli isolates harboured the bla_OXA-48 gene. Pseudomonas isolates were positive for the bla_VIM gene as a single gene. The Carba NP strip method exhibited high sensitivity and specificity, but the tube method had a higher diagnostic performance in Pseudomonas isolates.
Conclusion: The current study highlights that Carba NP strip test can be a reliable and excellent alternative to other tedious and expensive standard techniques, making carbapenem resistance diagnosis reachable to routine laboratories. The Carba NP strip test is simple, inexpensive, and rapid. It can be implemented in low-resource healthcare settings for early detection of carbapenem resistance, hence initiating proper therapy. Further studies on broad scales are recommended to study the effect of other carbapenemase genes on sensitivity and specificity‎‎‎‎‎‎‎.