Diversity of TEM Mutants in Proteus Mirabilis
Overview
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In a survey of resistance to amoxicillin among clinical isolates of Proteus mirabilis, 10 TEM-type beta-lactamases were characterized: (i) the well-known penicillinases TEM-1 and TEM-2, the extended-spectrum beta-lactamases (ESBLs) TEM-3 and TEM-24, and the inhibitor-resistant TEM (IRT) TEM-44 and (ii) five novel enzymes, a penicillinase TEM-57 similar to TEM-1, an ESBL TEM-66 similar to TEM-3, and three IRTs, TEM-65, TEM-73, and TEM-74. The penicillinase TEM-57 and the ESBL TEM-66 differed from TEM-1 and TEM-3, respectively, by the amino acid substitution Gly-92-->Asp (nucleotide mutation G-477-->A). This substitution could have accounted for the decrease in pIs (5.2 for TEM-57 and 6.0 for TEM-66) but did not necessarily affect the intrinsic activities of these enzymes. The IRT TEM-65 was an IRT-1-like IRT (Cys-244) related to TEM-2 (Lys-39). The two other IRTs, TEM-73 and TEM-74, were related to IRT-1 (Cys-244) and IRT-2 (Ser-244), respectively, and harbored the amino acid substitutions Leu-21-->Phe and Thr-265-->Met. In this study, the ESBLs TEM-66, TEM-24, and TEM-3 were encoded by large (170- to 180-kb) conjugative plasmids that exhibited similar patterns after digestion and hybridization with the TEM and AAC(6')I probes. The three IRTs TEM-65, TEM-73, and TEM-74 were encoded by plasmids that ranged in size from 42 to 70 kb but for which no transfer was obtained. The characterization of five new plasmid-mediated TEM-type beta-lactamases and the first report of TEM-24 in P. mirabilis are evidence of the wide diversity of beta-lactamases produced in this species and of its possible role as a beta-lactamase-encoding plasmid reservoir.
Ramatla T, Ramaili T, Lekota K, Mileng K, Ndou R, Mphuthi M Vet Med Sci. 2024; 10(2):e1371.
PMID: 38357843 PMC: 10867704. DOI: 10.1002/vms3.1371.
Regulatory Mechanisms of the LuxS/AI-2 System and Bacterial Resistance.
Wang Y, Liu B, Grenier D, Yi L Antimicrob Agents Chemother. 2019; 63(10).
PMID: 31383657 PMC: 6761564. DOI: 10.1128/AAC.01186-19.
Eguale T, Birungi J, Asrat D, Njahira M, Njuguna J, Gebreyes W Antimicrob Resist Infect Control. 2017; 6:13.
PMID: 28105330 PMC: 5240271. DOI: 10.1186/s13756-017-0171-6.
Corvec S, Beyrouthy R, Cremet L, Aubin G, Robin F, Bonnet R Antimicrob Agents Chemother. 2013; 57(5):2410-2.
PMID: 23478954 PMC: 3632918. DOI: 10.1128/AAC.01761-12.
Novais A, Baquero F, Machado E, Canton R, Peixe L, Coque T Antimicrob Agents Chemother. 2009; 54(2):825-34.
PMID: 19995930 PMC: 2812134. DOI: 10.1128/AAC.00959-09.