Association between ESBL Production and the Presence of magA Gene among the Clinical Isolates of Klebsiella pneumoniae

Klebsiella pneumoniae (K. pneumoniae) causes a wide range of nosocomial and community-acquired infections. In recent decades, K. pneumoniae has been known as the agent of community-acquired primary pyogenic liver abscess. In attempts to find the causes of this disease, researchers found a new virulence gene called magA (mucoviscosity-associated gene A). The present study was performed to determine the prevalence rate of magA gene among the extended-spectrum beta lactamase (ESBL)-positive and ESBL-negative K. pneumoniae strains.

The current cross-sectional study was conducted on 130 K. pneumoniae isolates collected from patients in Imam Reza hospital and its associated clinics in Mashhad city (Iran) from May 2011 to July 2012. The presence of K. pneumoniae species was confirmed by conventional microbio­logical methods. Samples were tested for the production of ESBLs by the double disk diffusion (DDS) test. PCR was performed to detect magA gene. The hypermucoviscosity (HV) phenotype of Klebsiella isolates was char­acterized by the string test.

magA gene was detected in 11(8.5%) out of 130 isolates of K. pneu­moniae. Of 11 isolates with positive result for magA gene, three cases were HV, and 8 cases were HV- phe­notype. Of 130 K. pneu­moniae isolates, 56 isolates were ESBL-positive, and 74 isolates were ESBL-negative. The magA gene was detected in 4 out of 56 (7.14%) ESBL-positive, and 7 out of 74 (9.46%) ESBL-negative samples.

In the present study, no correlation was observed between the presence of magA gene and the production of ESBL in K. pneumoniae strains isolated from different clinical samples in Mashhad.