Genotyping and antimicrobial susceptibility of Salmonella enterica serotype Panama isolated in Taiwan
Hao-Yuan Lee, Yao-Jong Yang, Lin-Hui Su, Chih-Hao Hsu, Yen-Ming Fu, Cheng-Hsun Chiu
Division of Pediatric Infectious Diseases, Department of Pediatrics, Chang Gung Children’s Hospital, Chang Gung University College of Medicine, Taoyuan; Division of Pediatric Gastroenterology, Department of Pediatrics, National Cheng Kung University Hospital, Tainan; and Department of Clinical Pathology, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan
Received: November 21, 2007 Revised: December 5, 2007 Accepted: January 23, 2008
Background and purpose:
Previous studies have indicated that Salmonella enterica serotype Panama causes systemic infections in humans. The present study was undertaken to gain more understanding of the molecular epidemiology and antimicrobial resistance of Salmonella Panama.
Antimicrobial susceptibility testing and molecular typing were performed on 9 clinical isolates by pulsed-field gel electrophoresis (PFGE). The presence of resistance genes, Salmonella genomic island 1 (SGI1), and integrons was examined by polymerase chain reaction. Plasmid profiles of these isolates were also determined.
Molecular typing showed 3 predominant PFGE types with 6 subtypes among these isolates. High rates of antimicrobial resistance to trimethoprim-sulfamethoxazole (66.7%), tetracycline (66.7%), chloramphenicol (66.7%), ampicillin (55.6%), streptomycin (55.6%), kanamycin (55.6%), and gentamicin (44.4%) were found. All 9 isolates were susceptible to ceftriaxone, cefixime, imipenem, amikacin, and ciprofloxacin. Isolates with PFGE type P1 and subtype P1-1 contained a class 1 integron and resistance genes sulI and str (p=0.048). Plasmids of 3 to 20 kb were found in all isolates belonging to PFGE type P1, subtypes P1-1 and P1-2, which were associated with multidrug resistance (p=0.012) and the resistant gene blaTEM (p=0.048). There was no SGI1 found in these 9 isolates.
In view of the high rates of drug resistance to the antimicrobial agents tested, extended-spectrum cephalosporins and fluoroquinolones seem to be a better choice for treatment of systemic infection caused by Salmonella Panama. There is a major clone (P1 and its subtypes) among the Salmonella Panama isolates. Multidrug resistance was conferred by integrons or plasmids, rather than SGI1.
Drug resistance; Genotype; Microbial sensitivity tests; Plasmids; Salmonella enterica
J Microbiol Immunol Infect. 2008;41:507-512.