Bacteria ; drug effects ; genetics ; Drug Resistance, Bacterial ; genetics ; Plasmids ; Quinolones ; pharmacology

OBJECTIVETo evaluate the role of outer membrane protein (Omp) F-deficiency and active efflux in the accumulation of hydrophilic fluoroquinolones ciprofloxacin (CPLX) and lomefloxacin (LMLX) in resistant E. coli strains.

METHODSFluoroquinolone accumulation in bacteria and the effect of active efflux were measured by a fluorescence method. The outer membrane proteins of the bacteria were analysed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). E. coli strains in this study included control strains JF701 and JF703 that are OmpC- or OmpF-deficient mutants of E. coli K-12, respectively, and the fluoroquinolone susceptible strain the fluoroquinolone susceptible strain of Escherichia coli (Ecs) and its in vitroselected resistant strains R2 and R256, and the clinical resistant isolates R5 and R6.

RESULTSThe steady-state accumulation concentration of each drug in Ecs appeared to be the same as in JF701, while in the OmpF-deficient strain JF703, it was 1/5 CPLX or 1/2 LMLX lower than that in JF701, but JF703 was still susceptible to fluoroquinolones. On the other hand, compared with susceptible strains, a 2- to 10-fold decrease in the accumulation of each drug was found in the resistant strains except R2, in which the accumulation was slightly higher than in JF703. After the addition of 2,4-dinitrophenol (DNP), accumulation of each drug increased, especially in resistant strains, indicating that the function of the active efflux (pump) system in these bacteria had been enhanced dramatically. Furthermore, both OmpF and OmpC in Ecs, OmpF-deficiency in R2 and R256 and OmpC-deficiency in R5 and R6 were observed.

CONCLUSIONThe decreased accumulation of hydrophilic fluoroquinolones in E. coli involved OmpF-deficiency and active efflux (pump), and the latter may be an important factor.

2,4-Dinitrophenol ; pharmacology ; Anti-Infective Agents ; metabolism ; pharmacology ; Ciprofloxacin ; metabolism ; pharmacology ; Drug Resistance, Bacterial ; Escherichia coli ; drug effects ; metabolism ; Fluoroquinolones ; Porins ; physiology ; Quinolones ; metabolism ; pharmacology

To explore new agents of quinolone derivatives with high antibacterial activity, 7-(4-alkoxyimino-3-methyl-3-methylaminopiperidin-1-yl)quinolones were designed and synthesized, and their activity against gram-positive and gram-negative strains was tested in vitro. Sixteen target compounds were obtained. Their structures were established by 1H NMR, HRMS and X-ray crystallographic analysis. Compounds 14k and 14m-14o show good antibacterial activity against the tested five gram-positive strains and five gram-negative strains (MIC: 0.25-16 micromg x mL(-1)), of which the most active compound 14o is 8-fold more potent than levofloxacin against S. pneumoniae (MIC: 4 microg x mL(-1)), and comparable to levofloxacin against S. aureus, S. epidermidis, E. faecalis and E. coli (MIC: 0.25-1 microg x mL(-1)), but generally less potent than gemifloxacin.
Anti-Bacterial Agents ; chemical synthesis ; chemistry ; pharmacology ; Gram-Negative Bacteria ; drug effects ; Gram-Positive Bacteria ; drug effects ; Molecular Structure ; Quinolones ; chemical synthesis ; chemistry ; pharmacology

A series of novel quinolinone acid-containing compounds were designed and synthesized. Their structures were confirmed with 1H NMR and MS. The target compounds were tested for anti-HIV-1 integrase activities in vitro with enzyme linked immunosorbent assay (ELISA). The result showed that D-2, D-4 and D-7 have anti-integrase activity with IC50 < 100 micromol L(-1).
HIV Integrase ; metabolism ; HIV Integrase Inhibitors ; chemical synthesis ; chemistry ; pharmacology ; Inhibitory Concentration 50 ; Quinolones ; chemical synthesis ; chemistry ; pharmacology ; Structure-Activity Relationship

INTRODUCTIONAt the time of the study, 3 plasmid-borne qnr determinants (qnrA, qnrB and qnrS) and 1 plasmid-borne aminoglycoside-modifying enzyme determinant that confers quinolone resistance (aac(6')-Ib-cr) had been described in the literature.

MATERIALS AND METHODSWe studied the prevalence of the 3 qnr determinants in a total of 117 nalidixic acid-resistant urinary isolates of Klebsiella pneumoniae (61 isolates) and Escherichia coli (56 isolates) using multiplex polymerase chain reaction (PCR). Further, a subset of the original strains (comprising 14 E. coli and 38 K. pneumoniae) showing reduced susceptibility to the aminoglycosides underwent PCR for aac(6')-Ib, followed by restriction digestion with BtsCI to detect the variant aac(6')-Ib-cr.

RESULTSTwenty-eight of 61 (45.9%) Klebsiella isolates were found to possess at least 1 qnr determinant. Only 1/56 (1.8%) E. coli isolates were found to possess a qnr determinant. Two of the Klebsiella isolates possessed 2 qnr determinants each (qnrB and qnrS). The predominant determinant was qnrB (19 isolates). There were 11 isolates harbouring qnrS, and only 1 with qnrA. 1/14 (7.1%) E. coli and 35/38 K. pneumoniae (92.1%) were found to possess aac(6')-Ib-cr. There was pairwise association between each of qnr, aac(6')-Ib-cr and the presence of an extended-spectrum beta-lactamase.

CONCLUSIONSA high prevalence of plasmid-mediated quinolone resistance determinants [i.e., qnrS, qnrB and aac(6')-Ib-cr] was found in quinolone-resistant K. pneumoniae isolated in a large hospital in Singapore.

Drug Resistance, Bacterial ; Escherichia coli ; drug effects ; isolation & purification ; Hospitals ; Humans ; Klebsiella pneumoniae ; drug effects ; isolation & purification ; Molecular Sequence Data ; Quinolones ; pharmacology ; R Factors ; Singapore ; Urine ; microbiology

OBJECTIVESTo investigate the correlation between mutation of GyrA and ParC genes and quinolone resistance in Neisseria Gonorrhoeae.

METHODSThe gene fragments of quinolone resistance-determining region (QRDR) in GyrA and ParC genes in 20 Neisseria gonorrhoeae strains clinically isolated in Wuxi, China, were sequenced, and the susceptibility of the 20 strains to quinolone was examined by agar diffusion method.

RESULTSThe mutations at the Asp95 point in GyrA gene were found in 20 strains. Of the 19 stains examined, 16 had mutations at the 86, 87, 88, 91 points in ParC genes.

CONCLUSIONSThe mutations of Asp95 in GyrA gene and Asp86, Ser87, Ser88, Glu91 in ParC gene contribute to quinolone resistance in Neisseria Gonorrhoeae.

Base Sequence ; DNA Gyrase ; genetics ; DNA Topoisomerase IV ; genetics ; Drug Resistance, Bacterial ; genetics ; Humans ; Molecular Sequence Data ; Mutation ; Neisseria gonorrhoeae ; drug effects ; genetics ; isolation & purification ; Quinolones ; pharmacology

Objective: To investigate the molecular characteristics of ciprofloxacin-cefotaxime-azithromycin co-resistant Salmonella enterica serovar Thompson (S. Thompson) isolates from sporadic cases of foodborne diseases and aquatic foods in Hunan province. Methods: Ciprofloxacin-cefotaxime-azithromycin co-resistant S. Thompson isolates were selected from samples, and broth microdilution method was used to determine the resistance to 11 antibiotics of these isolates in vitro. Whole genome sequencing was used for investigating antimicrobial resistance gene patterns and phylogenetic relationships of strains. Results: Nine ciprofloxacin-cefotaxime-azithromycin co-resistant isolates were recovered from 19 S. Thompson isolates. Among nine ciprofloxacin-cefotaxime-azithromycin co-resistant isolates, eight of them harbored IncC plasmids, simultaneously carrying plasmid-mediated quinolone resistance (PMQR) genes qepA and qnrS1, β-lactamase resistance gene bla_CMY-2, azithromycin resistance gene mph(A), and one isolate harbored IncR plasmid, and carried PMQR genes qnrB4 and aac(6')-Ib-cr, bla_OXA-10 and mph(A). Genetic environment analysis showed that qnrS1, qepA, mph(A) and bla_CMY-2 genes might be integrated on genomes of strains by ISKra4, IS91, IS6100 and ISEcp1, respectively. Phylogenetic core genome comparisons demonstrated that ciprofloxacin-cefotaxime-azithromycin co-resistant isolates from patients and aquatic foods were genetically similar and clustered together. Conclusion: Ciprofloxacin-cefotaxime-azithromycin co-resistant S. Thompson isolates have been isolated from both human and aquatic food samples, suggesting that the spread of multidrug resistant Salmonella between human and aquatic animals.
Animals ; Humans ; Ciprofloxacin ; Cefotaxime ; Azithromycin ; Serogroup ; Phylogeny ; Drug Resistance, Multiple, Bacterial/genetics* ; Anti-Bacterial Agents/pharmacology* ; Salmonella ; Quinolones ; Foodborne Diseases ; Plasmids ; Salmonella enterica ; Microbial Sensitivity Tests

In the past 3 decades, classical extended-spectrum beta-lactamases (ESBLs) have probably been the main contributors to gram-negative antimicrobial resistance in Singapore. These appear to be being replaced by the newer CTX-M ESBLs. Metallo-beta-lactamases are found in Pseudomonas aeruginosa but do not seem to have spread widely in Acinetobacter spp. and Enterobacteriaceae. Carbapenem-hydrolysing oxacillinases are prevalent in multidrug-resistant Acinetobacter spp. More insidious developments include the emergence of plasmid AmpC beta-lactamases and multifactorial quinolone resistance in Enterobacteriaceae.
Anti-Bacterial Agents ; pharmacology ; Carbapenems ; pharmacology ; Cephalosporins ; pharmacology ; Drug Resistance, Microbial ; Gram-Negative Bacteria ; drug effects ; History, 20th Century ; History, 21st Century ; Humans ; Microbial Sensitivity Tests ; Quinolones ; pharmacology ; Singapore ; beta-Lactamases ; genetics

BACKGROUNDOver the last decade, Clostridium difficile infection (CDI) has emerged as a significant nosocomial infection, yet little has been reported from China. This study aimed to characterize the clinical and microbiological features of CDI from a hospital in Shanghai.

METHODSPatients with CDI seen between December 2010 and March 2013 were included in this study, of which clinical data were retrospectively collected. The microbiological features of corresponding isolates were analyzed including genotype by multi-locus sequence typing (MLST), antimicrobial susceptibility, toxin production, sporulation capacity, biofilm formation, and motility.

RESULTSNinety-four cases of CDI were included during this study period, 12 of whom were severe cases. By reviewing the clinical data, all patients were treated empirically with proton pump inhibitor or antibiotics or both, and they were distributed widely across various wards, most frequently to the digestive ward (28/94, 29.79%). Comparing the severe with mild cases, no significant differences were found in the basic epidemiological data or the microbiological features. Among the 94 isolates, 31 were toxin A-negative toxin B-positive all genotyped as ST37. They generated fewer toxins and spores, as well as similar amounts of biofilm and motility percentages, but exhibited highest drug resistance to cephalosporins, quinolones, macrolide-lincosamide and streptogramin (MLSB), and tetracycline.

CONCLUSIONSNo specific clinical genotype or microbiological features were found in severe cases; antimicrobial resistance could be the primary reason for epidemic strains leading to the dissemination and persistence of CDI.

Anti-Bacterial Agents ; pharmacology ; Biofilms ; drug effects ; Cephalosporins ; pharmacology ; China ; Clostridium difficile ; drug effects ; genetics ; isolation & purification ; Genotype ; Multilocus Sequence Typing ; methods ; Quinolones ; pharmacology ; Tertiary Healthcare ; statistics & numerical data ; Tetracycline ; pharmacology

OBJECTIVE: To determine the effect of rebamipide on the expression of Toll-like recepter 4 (TLR4) and TNF-alpha release in pulmonary epithelial cell line A549. METHODS: Lipopolysaccharide (LPS) was used to induce A549 in vitro, which was divided into 4 groups: a control group, a model group(LPS), and 2 intervention groups (10 mg/L rebamipide plus LPS; 30 mg/L rebamipide plus LPS). TNF-alpha release was detected with ELISA and expression of TLR4 was detected with RT-PCR and Western blot. RESULTS: A549 cells were stimulated with LPS and TNF-alpha release was increased compared with the control group (P<0.01), peaking at 6 h. Expression of TLR4 was also increased compared with the control group (P<0.01), but it was inhibited by rebamipide compared with the model group (P<0.05). There was no significant difference between the 2 intervention groups (P>0.05). CONCLUSION The antiinflammatory mechanism of rebamipide may be reducing cytokine release by inhibiting TLR4 expression. Rebamipide may be used as a supplementary anti-infection drug.
Alanine ; analogs & derivatives ; pharmacology ; Anti-Inflammatory Agents, Non-Steroidal ; pharmacology ; Cell Line ; Epithelial Cells ; cytology ; Humans ; Lipopolysaccharides ; pharmacology ; Lung ; cytology ; metabolism ; Quinolones ; pharmacology ; Toll-Like Receptor 4 ; genetics ; metabolism ; Tumor Necrosis Factor-alpha ; genetics ; metabolism