Original article

Genetic characteristic of class 1 integrons in proteus mirabilis isolates from urine samples

¹ Division of Infectious Disease, Department of Internal Medicine, Tungs’ Taichung MetroHarbor Hospital, Taichung 433, Taiwan
² Department of Health Food, Chung Chou University of Science and Technology, Changhua 510, Taiwan
³ Graduate Institute of Biomedical Sciences, Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan
⁴ Molecular Infectious Disease Research Center, Department of Pediatrics, Chang Gung Children’s Hospital and Chang Gung Memorial Hospital, Taoyuan 333, Taiwan
⁵ Graduate Institute of Basic Medical Science, School of Medicine, China Medical University, Taichung 404, Taiwan
⁶ Department of Medical Research and Department of Laboratory Medicine, China Medical University Hospital, Taichung 404, Taiwan
⁷ Department of Nursing, Asia University, Taichung 413, Taiwan
⁸ Department of Clinical Laboratory, Jen-Ai Hospital, Taichung 412, Taiwan

^* The Institute of Medical Science and Department of Microbiology, China Medical University, No. 91, Hsueh-Shih Road, Taichung 404, Taiwan. E-mail address: ltwu@mail.cmu.edu.tw (L.-T. Wu)

Received: 28 December 2016
Accepted: 20 January 2017

Abstract

Background: Proteus mirabilis is an opportunistic pathogen, commonly associated with complicated urinary tract infections (UTIs). UTIs caused by multidrug-resistant Proteus mirabilis have increased worldwide. Multidrug-resistance of Gram-negative enteric bacteria is usually associated with class 1 integrons.

Purposes: To investigate the prevalence and characterize gene cassettes of class 1 integrons in multidrug-resistant P. mirabilis

Methods: From 2006 to 2008, 314 P. mirabilis isolates from urine were collected from a regional teaching hospital. Antimicrobial resistance of the isolates was determined by disk diffusion methods. The phenotypic confirmatory test of extended-spectrum β-lactamase (ESBL) production was performed as described in the Clinical and Laboratory Standards Institute (CLSI) guideline. The genetic organization of the class 1 integron cassettes was investigated by PCR, cloning, and sequencing of the regions surrounding these genes.

Results: Seventy-nine (25%, 79/314) P. mirabilis isolates were ESBL-producing and most ESBL-producing P. mirabilis were positive for bla_CTX-M. Class 1 integrons were presented in 76 isolates (24.2%, 76/314), and were more frequently found in ESBL-positive (55/79, 70%) than ESBL-negative (21/235, 8.9%) P. mirabilis isolates. The most prevalence of the cassettes encoded resistance genes were aminoglycoside (aac(6’)-Ib, aacA7, aadAl, aadA2, and aadAla), trimethoprim (dfrAl and dfrA12) and chloramphenicol (catB3 and cmlA6). The most prevalent cassette of dfr12-orfF-aadA2 was found in 49 isolates. The cassette array aadB-catB3-oxa10-aadA1 was first found in P. mirabilis. The enterobacterial repetitive intergenic consensus (ERIC)-PCR fingerprinting patterns were detected in these 76 integron positive P. mirabilis isolates and belonged to 8 profiles.

Conclusion: This study investigated the prevalence and characterized gene cassettes of class 1 integrons in MDR P. mirabilis isolates from urine samples. The frequency of gene cassettes in P. mirabilis were partially by clonal spread of the carriers and the results could provide information for effective antimicrobial therapy and infection control.