BackgroundThe emergence of carbapenem-resistant Klebsiella pneumoniae poses a serious problem to antibiotic management. We investigated the β-lactamases in a group of carbapenem-resistant K. pneumoniae clinical isolates from Turkey.MethodsThirty-seven strains of K. pneumoniae isolated from various clinical specimens were analyzed by antimicrobial susceptibility testing, PCR for the detection of β-lactamase genes, DNA sequencing, and repetitive extragenic palindronic (REP)-PCR analysis.ResultsAll 37 isolates were resistant to ampicillin, ampicillin/sulbactam, piperacillin, piperacillin/tazobactam, ceftazidime, cefoperazone/sulbactam, cefepime, imipenem, and meropenem. The lowest resistance rates were observed for colistin (2.7%), tigecycline (11%), and amikacin (19%). According to PCR and sequencing results, 98% (36/37) of strains carried at least one carbapenemase gene, with 32 (86%) carrying OXA-48 and 7 (19%) carrying NDM-1. No other carbapenemase genes were identified. All strains carried a CTX-M-2-like β-lactamase, and some carried SHV- (97%), TEM- (9%), and CTX-M-1-like (62%) β-lactamases. Sequence analysis of blaTEM genes identified a blaTEM-166 with an amino acid change at position 53 (Arg53Gly) from blaTEM-1b, the first report of a mutation in this region. REP-PCR analysis revealed that there were seven different clonal groups, and temporo-spatial links were identified within these groups.ConclusionsCombinations of β-lactamases were found in all strains, with the most common being OXA-48, SHV, TEM, and CTX-M-type (76% of strains). We have reported, for the first time, a high prevalence of the NDM-1 (19%) carbapenemase in carbapenem-resistant K. pneumoniae from Turkey. These enzymes often co-exist with other β-lactamases, such as TEM, SHV, and CTX-M β-lactamases.

An easy efficient method for the synthesis of N-(3,5-dichlorophenyl)-5-alkyl/aryl-3H-1,2,4-triazol-3-one derivatives under microwave irradiation has been developed using the reaction of 3,5-dichloroaniline and ethoxycarbonylhydrazones. This reaction occurs more efficiently and faster than the conventional heating method. We obtained 5mercapto-1,3,4-oxadiazol derivatives by this method. The newly synthesised compounds have been tested for their antimicrobial activity against Enterobacter cloaceae, Escherichia coli, Klebsiella pneumonie, Pseudomonas aeruginosa, Proteus vulgaris, Salmonella typhimurium, Yersinia pseudotuberculosis, Bacillus subtilis and Staphylococcus aereus.

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A new series of ciprofloxacin hybrid compounds as new type of antimicrobial agents were synthesized and evaluated for antibacterial activity against Gram‐positive and Gram‐negative bacteria.