ABSTRACT
Indole negative Proteus species are invariably incorrectly identified as Proteus mirabilis, often missing out isolates of Proteus penneri. We report a case of extended spectrum beta lactamase producing and multidrug-resistant P. penneri isolated from pus from pressure sore of a patient of road traffic accident. Correct and rapid isolation and identification of such resistant pathogen are important as they are significant nosocomial threat.
Subject(s)
Drug Resistance, Multiple, Bacterial , Proteus Infections/diagnosis , Proteus penneri/enzymology , Proteus penneri/isolation & purification , Wound Infection/diagnosis , beta-Lactamases/metabolism , Accidents, Traffic , Adult , Bacteriological Techniques , Diagnostic Errors , Humans , Male , Proteus Infections/microbiology , Wound Infection/microbiology , Wounds and Injuries/complicationsABSTRACT
INTRODUCTION: The aim of this study was to evaluate betalactam resistance within the genus Proteus and characterize the betalactamases responsible for this resistance. METHODS: We analyzed 99 strains (87, P. mirabilis; 10 P. vulgaris, and 2, P. penneri) isolated from patients at one University Hospital. Antibiotic susceptibility tests were performed according to NCCLS recommendations. Presence of extended spectrum betalactamases (ESBL) was inferred by both double disk diffusion tests and minimum inhibitory concentration (MIC) of third and fourth generation cephalosporins alone and in the presence of clavulanic acid. Isoelectric points (pI) of the enzymes were estimated by isoelectrofocusing and the presence of the encoding genes was confirmed by polymerase chain reaction (PCR). RESULTS: A broad spectrum betalactamase could be detected in those isolates (28%) resistant to penicillin and first generation cephalosporins while CTX-M-2 enzyme could be detected in P. mirabilis isolates resistant to third and fourth generation cephalosporins (18%). One of the P. vulgaris displayed reduced susceptibility to cefotaxime due to an enzyme of pI 7.4, while resistance to cefotaxime in one P. penneri was related to an enzyme of pI 6.8. Both enzymes were active on cefotaxime (1,000 mg/l) in the iodometric assay. CONCLUSION: The broad extended spectrum betalactamase within genus Proteus was TEM-1, while CTX-M-2 was the ESBL responsible for the third and fourth generation cephalosporins in P. mirabilis. In P. vulgaris and P. penneri this resistance was associated with the hyperproduction of the chromosomal encoded betalactamase.
