Prevalence of Plasmid-Mediated ampC Genes in Clinical Isolates of Enterobacteriaceae from Cairo, Egypt
Nevine Fam *
Department of Microbiology, Theodor Bilharz Research Institute, Cairo, Egypt.
Doaa Gamal
Department of Microbiology, Theodor Bilharz Research Institute, Cairo, Egypt.
Manal El Said
Department of Microbiology, Theodor Bilharz Research Institute, Cairo, Egypt.
Inas El Defrawy
Department of Microbiology, Theodor Bilharz Research Institute, Cairo, Egypt.
Ehab El Dadei
Department of Biochemistry, Theodor Bilharz Research Institute, Cairo, Egypt.
Soheir El Attar
Department of Medical Microbiology and Immunology, Faculty of Medicine, Cairo University, Cairo, Egypt.
Ashraf Sorur
Department of Medical Microbiology and Immunology, Faculty of Medicine, Cairo University, Cairo, Egypt.
Salwa Ahmed
U.S. Naval Medical Research Unit No.3, Abbassia, Cairo, Egypt.
John Klena
U.S. Naval Medical Research Unit No.3, Abbassia, Cairo, Egypt.
*Author to whom correspondence should be addressed.
Abstract
Aims: To determine the prevalence of acquired pAmpCs in clinically important and relevant enterobacterial species and to characterize the molecular types of pAmpC present in our geographic area.
Methodology: Sixty Enterobacterial clinical isolates resistant to third generation cephalosporins and to cephamycins were included in the study. Samples were collected for a period of 6 months between July 2008 and December 2008 from Theodor Bilharz Research Institute (TBRI), Egypt. Bacterial species were identified using API E20. AmpC genes clusters: (bla ACC, bla EBC, bla FOX, bla CMY, bla MOX, and bla DHA) were tested by PCR and DNA sequencing. Clonal relatedness of AmpC-producing Klebsiellae isolates was determined by Pulsed Field Gel Electrophoresis (PFGE).
Results: AmpC genes were detected in 28.3% (17/60) of the study population including E. coli, Klebsiella and Proteus mirabilis (P mirabilis). CMY-2 enzyme was found disseminating in all 6 AmpC-positive Escherichia coli (E. coli) and in 6/10 of Klebsiellae species. Only one Klebsiella pneumonia (K. pneumonia) isolate harbored CMY-4 while DHA-1 was detected in 3 Klebsiellae and in one P. mirabilis isolate. PFGE patterns showed no clonal relatedness among the 6 CMY-2-positive Klebsiella isolates.
Conclusion: Plasmid-mediated AmpC enzymes are important mechanisms of resistance to ß- lactam drugs. CMY-2 and DHA-1 are the most common gene clusters of pAmpC in our region. AmpC-type resistance in our hospital setting is not due to the dissemination of clonal strains but due to the spread of resistant genes. This is the first report from Egypt identifying DHA-1 and CMY-4 in enterobacterial isolates.
Keywords: AmpC β-lactamases, Klebsiella spp., E. coli, P. mirabilis, PCR, DNA sequencing, PFGE