Introduction Fluoroquinolones are widely used broad-spectrum antibiotics. Recently, increased rate of resistance to this antibiotic has been observed in Klebsiella pneumoniae. The aim of the present study was to determine the presence of quinolone resistance determining regions (QRDR) mutation genes and plasmid-mediated quinolone resistance (PMQR) determinants in clinical isolates of ciprofloxacin-resistant K. pneumoniae. Material and Methods The study included 110 nonduplicate ciprofloxacin-resistant K. pneumoniae clinical isolates. Antibiotic susceptibility testing by disk diffusion method and minimum inhibitory concentration (MIC) by agar dilution methods for ciprofloxacin was performed according to the recommendations of Clinical Laboratory Standards Institute. The presence of QRDR genes and PMQR genes was screened by polymerase chain reaction (PCR) amplification. Result All 110 isolates were resistance to ciprofloxacin, levofloxacin, and ofloxacin. As much as 88% of the isolates exhibited high-level of MIC to ciprofloxacin. Among the 110 isolates, 94(85%) harbored gyrA and 85 (77%) gyrB. The parC and parE genes were detected in 88 (80%) and 64 (58%) isolates. qnrB was detected in 13 (12%) isolates and qnrS in 5 (4.5%) isolates. Two (1.8%) isolates carried both qnrB and qnrS genes. The acc (6')-Ib-cr gene was found in 98 (89%) isolates and oqxAB was detected in 7 (6.3%) isolates. One (0.9%) isolate carried qnrB, acc(6')-Ib-cr and oqxAB genes. Conclusion The prevalence of acc (6')-Ib-cr gene is high among PMQR determinants, followed by qnrB, oqxAB and qnrS.

Introduction Pseudomonas aeruginosa and Acinetobacter baumannii are important pathogens in health care–associated infections. Fluoroquinolone resistance has emerged in these pathogens. In this study, we aimed to determine the occurrence of plasmid-mediated quinolone resistance (PMQR) determinants (qnrA, qnrB, qnrS, aac(6′)-Ib-cr, oqxAB, and qepA) by polymerase chain reaction (PCR) and the transmissibility of plasmid-borne resistance determinants in clinical isolates of P. aeruginosa and A. baumannii. Materials and Methods The study included P. aeruginosa (85) and A. baumannii (45) which were nonduplicate, clinically significant, and ciprofloxacin resistant. Antibiotic susceptibility testing was done by disk diffusion method for other antimicrobial agents, namely amikacin, ceftazidime, piperacillin/tazobactam, ofloxacin, levofloxacin, and imipenem. Minimum inhibitory concentration of ciprofloxacin was determined. Efflux pump activity was evaluated using carbonyl-cyanide m-chlorophenylhydrazone (CCCP). The presence of PMQR genes was screened by PCR amplification. Transferability of PMQR genes was determined by conjugation experiment, and plasmid-based replicon typing was performed. Results Resistance to other classes of antimicrobial agents was as follows: ceftazidime (86.9%), piperacillin/tazobactam (73.8%), imipenem (69.2%), and amikacin (63.8%). The minimal inhibitory concentration (MIC)50 and MIC90 for ciprofloxacin were 64 and greater than or equal to 256 µg/mL, respectively. There was a reduction in MIC for 37 (28.4%) isolates with CCCP. In P. aeruginosa, 12 (14.1%) isolates harbored qnrB, 12 (14.1%) qnrS, 9 (10.5%) both qnrB and qnrS, 66 (77.6%) aac(6′)-Ib-cr, and 3 (3.5%) oqxAB gene. In A. baumannii, qnrB was detected in 2 (4.4%), 1 (2.2%) harbored both the qnrA and qnrS, 1 isolate harbored qnrB and qnrS, 21 (46.6%) aac(6′)-Ib-cr, and 1 (2.2%) isolate harbored oqxAB gene. Notably, qepA gene was not detected in any of the study isolates. Conjugation experiments revealed that 12 (9.2%) were transferable. Of the transconjugants, seven (58.3%) belonged to IncFII type plasmid replicon, followed by four (33.3%) IncA/C and one (8.3%) IncFIC type. Conclusion The plasmid-mediated resistance aac(6′)-Ib-cr gene is primarily responsible for mediating fluoroquinolone resistance in clinical isolates of P. aeruginosa and A. baumannii. The predominant plasmid type is IncFII.

Introduction Aminoglycosides are formidable broad-spectrum antibiotics used in clinical settings; woefully their usage has been reduced by the emergence and distribution of resistance mainly due to aminoglycoside modifying enzymes (AME). Purpose This study was performed to determine the diverse prevalence of AME and their pattern of occurrence in the clinical isolates of gram-negative bacteria. This study also aimed to detect the presence of AMEs that are prevalent in gram-positive bacteria, among gram negatives. Materials and Methods A total number of 386 clinical isolates were included in this study. Polymerase chain reaction revealed the prevalence rate of AMEs screened [aac(6′)-lb, aac(3′)-I, aac(3′)-II, aac(3′)-VI, ant(2′)-I, ant(4′)-IIb, aac(3′)-III, aac(3′)-IV, aph(2′)-Ib, aph(2′)-Ic, aph(2′)-Id, aac (6′)-Ie- aph(2′)-Ia, and aph(3′)-IIIa]. Conjugation experiment was performed for the clinical isolates which harbored any one of the AME which was prevalent in gram-positive bacteria [aph(3′)-IIIa, aac(6′)-Ie-aph(2′)-Ia]. Results aac(6′)-lb is the most prevalent AME, followed by aac(3′)-I, aph(3′)-VI, aac(3′)-VI, and aac(3′)-II. The AMEs such as ant (2′)-I, ant(4′)-IIb, aac(3′)-III, aac(3′)-IV, aph(2′)-Ib, aph(2′)-Ic, and aph(2′)-Id were not established in our study isolates. The rate of prevalence of aph(3′)-IIIa, aac(6′)-Ie-aph(2′)-Ia—the AMEs encountered in gram-positive and their co-existence was 19.68% and the conjugation experiment revealed their transfer via plasmids. Conclusion This is the first report from India revealing the presence and prevalence of AMEs which are often encountered among gram-positive bacteria in gram negatives and their presence on conjugative plasmids.

BACKGROUND: The carbapenemase-encoding genes, bla NDM- and bla OXA-48 - like , confer resistance to all the known beta-lactams and are encountered along with other beta-lactamase-encoding genes and/or 16S ribosomal RNA (rRNA)-methylating genes. The co-occurrence of bla NDM and bla OXA-48 - like on a single plasmid is a rare occurrence. AIM AND OBJECTIVE: The purpose of the study was to characterize the plasmids in Klebsiella pneumoniae isolates producing 16S rRNA methyltransferase along with bla NDM , bla OXA-48-like , and other resistance encoding genes. MATERIALS AND METHODS: One-hundred and seventeen K. pneumoniae clinical isolates which were resistant to aminoglycosides were collected. Polymerase chain reaction-based screening for 16S rRNA methyltransferase genes armA, rmtB, and rmtC; carbapenamase genes bla NDM , bla OXA-48-like , bla IMP, bla VIM, and bla KPC ; and other resistance genes such as bla TEM, bla SHV, bla CTX-M , and qnr (A, B, and S) determinants acc (6') Ib-cr was performed. Conjugation experiment was carried out for seven isolates that anchored bla NDM and bla OXA-48-like along with any one of the 16S rRNA methyltransferases. The plasmid-based replicon typing for different plasmid-incompatible (Inc) group was performed on the conjugatively transferable plasmids. RESULTS: Among the 16S rRNA methyltransferases, armA was more predominant. bla NDM and bla OXA-48 -like were present in 56 (47.86%) and 22 (18.80%) isolates, respectively. Out of seven isolates which were conjugatively transferable, only four had bla NDM and bla OXA-48 - like on the same plasmid and they belonged to Inc N and A/C replicon. Three isolates co-harbored 16S rRNA methyltransferases armA, rmtB, and rmtC, and out of the them, one isolate harbored two 16S rRNA methyltransferases armA and rmtB, on the single-plasmid replicon A/C. CONCLUSION: This is the first report revealing the coexistence of bla NDM and bla OXA-48 - like co-harboring two 16S rRNA methylases on a single conjugative plasmid replicon belonging to incompatibility group A/C.