There have been conflicting data about the interactions between vancomycin and beta-lactam agents against Staphylococcus aureus strains with heterogeneous resistance to vancomycin. We evaluated the efficacy of these combinations against Mu 3 and heterogeneously vancomycin-resistant S. aureus (hetero-VRSA) strains which were isolated from Korean patients using a population analysis method. Antagonistic effects were observed when less than 1 g/mL of beta-lactam antibiotics was combined with vancomycin, whereas synergistic effects were noticed with more than 4 microgram/mL of beta-lactam antibiotics. The antagonistic effects at low concentrations of beta-lactams were most prominent at 2 microgram/mL of vancomycin, which were the vancomycin MICs of tested hetero-VRSA strains. This study showed the variable effects of vancomycin- beta-lactam combinations depending on the concentrations of beta-lactam antibiotics and this property could be used to develop screening methods for hetero-VRSA strains.
Anti-Bacterial Agents/*pharmacology ; Cefotaxime/pharmacology ; Drug Synergism ; Human ; In Vitro ; Microbial Sensitivity Tests ; Oxacillin/*pharmacology ; Staphylococcus aureus/*drug effects ; Vancomycin/*pharmacology ; Vancomycin Resistance ; beta-Lactam Resistance

OBJECTIVETo explore the diversity changes of microbial communities and bla(CTX-M) in an urban river sediment community with cefotaxime treatment.

METHODSThe terminal restriction fragment length polymorphism (T-RFLP) of 16S rDNA was employed to analyze the bacteria community, and the bla(CTX-M) was determined using nested PCR. The sediment was treated by cefotaxime at the concentrations of 0, 6.4, 64, and 320 mg/L.

RESULTSAccording to statistical analysis of the T-RFs, no significant correlation was observed between the antibiotic treatment and the microbial community change, but incubation in laboratory conditions had significant effect on the microbial diversity. The PCR results showed that the diversity of bla(CTX-M) decreased after the laboratory incubation.

CONCLUSIONAs there are diverse antibiotic resistant bacteria in the sediments with prior pollution by antibiotics, the whole community can be inert to the antibiotic treatment. Nevertheless, the ex situ treatment conditions in laboratory studies have a significant impact on the community structures.

Biodiversity ; Cefotaxime ; pharmacology ; Ceftazidime ; pharmacology ; Cities ; Escherichia coli Proteins ; genetics ; Geologic Sediments ; microbiology ; Polymorphism, Restriction Fragment Length ; RNA, Ribosomal, 16S ; genetics ; Rivers ; Water Microbiology ; beta-Lactamases ; genetics

In order to identify ceftriaxone and its analogs whether has the function of anti-tolerance of morphine and study the dose-effect relation of ceftriaxone in mice, hot plate method to measure pain threshold of mouse and naloxone withdrawal models were carried out and compared with normal saline group. Ceftriaxone and cefotaxime had the effect of anti-tolerance and anti-dependence of morphine notably. And ceftriaxone has the effect of anti-tolerance of morphine in a dose dependent manner.
Animals ; Anti-Bacterial Agents ; pharmacology ; Cefotaxime ; pharmacology ; Ceftriaxone ; pharmacology ; Dose-Response Relationship, Drug ; Drug Tolerance ; Female ; Mice ; Morphine ; pharmacology ; Morphine Dependence ; prevention & control ; Pain Threshold ; drug effects ; Random Allocation ; Substance Withdrawal Syndrome ; physiopathology

OBJECTIVETo evaluate the antimicrobial activity of total alkaloids extracted from Sophorea alopecuroides L. (TASA) against clinical isolated extended-spectrum beta-lactamases (ESBLs) producing Escherichia coli (E. coli) strains.

METHODSThe antibacterial activity of TASA either itself or in combination with cefotaxime (CTX) or ceftazidime (CAZ) was investigated by using the microbroth dilution method and phenotypic confirmatory disk diffusion test against three clinical isolated ESBLs-producing E. coli strains; the interactions of TASA and CTX or CAZ were ascertained by evaluating the fractional inhibitory concentration index (FICI).

RESULTSThe antibacterial activity of either TASA itself or in combination with CTX or CAZ was found. The minimum inhibitory concentration (MICs) of TASA against the ESBLs producing isolates was 12.5 mg/mL. In the combinations with a sub-inhibitory concentration of TASA, a synergistic effect on CTX and CAZ against the ESBLs producing isolates was observed. Similarly, the isolates exposed to lower dose of TASA yielded an increased susceptibility to CTX and CAZ by 8-16 folds determined by microdilution assay. Moreover, enzymatic detection of ESBLs demonstrated that TASA induced reversal resistance to CTX and CAZ partially by a mechanism of inhibition of ESBLs activity in these isolates. Additionally, in the tested isolates following the exposure of TASA, molecular analysis verified the SHV-type beta-lactamase encoding ESBL gene in these isolates, and no mutation was introduced into the ESBL gene.

CONCLUSIONSThese results suggest that TASA could be used as a source of natural compound with pharmacological activity of reversal resistance to antimicrobial agent. These findings also indicated that the application of the TASA in combination with antibiotics might prove useful in the control and treatment of infectious diseases caused by the ESBLs producing enterobacteriaceae.

Alkaloids ; isolation & purification ; pharmacology ; Anti-Bacterial Agents ; pharmacology ; Base Sequence ; Cefotaxime ; pharmacology ; Ceftazidime ; pharmacology ; DNA Primers ; Escherichia coli ; drug effects ; enzymology ; Microbial Sensitivity Tests ; Polymerase Chain Reaction ; Sophora ; chemistry ; beta-Lactamases ; biosynthesis

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

OBJECTIVETo elucidate the epidemic condition and molecular subtyping of ciprofloxacin and cefotaxime co-resistant Salmonella Indiana (S. Indiana) isolated from retail chicken carcasses in six provinces of China.

METHODSA total of 2 647 Salmonella strains isolated from retail chicken carcasses collected from six provinces of China were subjected to antimicrobial susceptibility testing. All Salmonella isolates co-resistant to ciprofloxacin and cefotaxime were further characterized by serotyping, extended-spectrum beta-lactamases (ESBLs) producing strains screening and pulsed field gel electrophoresis (PFGE) typing.

RESULTSAmong 2 629 Salmonella isolates tested, 227 (8.52%) isolates were co-resistant to ciprofloxacin and ceftazidime/cefotaxime (Beijing: 11.67% (99/874), Jilin: 8.20% (60/726), Guangdong: 1.39% (7/502), Jiangsu: 15.61% (42/260), Shaanxi: 8.56% (16/186), Inner Mongolia: 0 (0/81)), and 224 of them were identified as S. Indiana. 213 (95.10%) isolates of S. Indiana were ESBLs producing strains. All ciprofloxacin and cefotaxime co-resistant S. Indiana isolates developed a multi-drug resistant profile and 17.86% (40/224) of them were resistant to all antibiotics tested except carbapenems, and 50.89% (114/224) of them resistant to 9 antibiotics, additionally, 25.45% (57/224) of them showed multi-drug resistance to 8 antibiotics. All ciprofloxacin and cefotaxime co-resistant S. Indiana isolates were divided into 32 PFGE clusters and 150 PFGE patterns. Strains of S. Indiana from same or different sampling site and time seemed to either share the same PFGE patterns or be differential to each other in different regions.

CONCLUSIONThe results indicated that chicken carcasses collected from parts of China were heavily contaminated by ciprofloxacin and cefotaxime co-resistant S. Indiana and could serve as an important reservoir of ciprofloxacin and cefotaxime co-resistant Salmonella. Molecular subtyping results indicated that cross contamination or common pollution source might be in these strains.

Animals ; Anti-Bacterial Agents ; pharmacology ; Cefotaxime ; pharmacology ; Chickens ; microbiology ; China ; Ciprofloxacin ; pharmacology ; Drug Resistance, Multiple, Bacterial ; Electrophoresis, Gel, Pulsed-Field ; Food Contamination ; Food Microbiology ; Meat ; microbiology ; Salmonella ; classification ; isolation & purification ; Serotyping ; beta-Lactamases

OBJECTIVETo study the resistance of staphylococcus aureus (S. aureus) isolated from children in Hangzhou to antibiotics and analyze the clinical value of mecA-PCR in determining oxacillin-resistant isolates.

METHODSS. aureus isolates were screened by using latex agglutination test and identified with GPI card of Vitek system. Antibiotics sensitivity tests were performed using disk diffusion methods and tests for sensitivity to oxacillin and vancomycin were performed with a further E-test method. The mecA gene was detected with polymerase-chain reaction (PCR).

RESULTSOf all 259 S. aureus strains, 185 from clinical specimens in inpatients and 74 from pharyngeal swabs in healthy children, 247 strains (95.8%) were beta-lactamase-positive and resistant to penicillin, while 91.1% of all strains were sensitive to oxacillin. All the strains were sensitive to vacomycin and 91.9% of all the strains were susceptible to cefotaxime and ceftriaxone. Resistance to erythromycin, tetracycline, clindamycin, trimethoprim-sulfamethoxazole, chloramphenicol, ofloxacin and rifampin were 48.3%, 30.9%, 21.6%, 11.2%, 10.0%, 2.3% and 1.5%, respectively. The resistance rate to oxacillin, cefotaxime, and ceftriaxone in clinical strains were significantly higher than that in carried strains (P < 0.05), while erythromycin-resistance rate was significantly higher in carried strains than that in clinical isolates (P < 0.05). The mecA-PCR showed that the control strain ATCC25923 and all oxacillin-sensitive S. aureus were mecA-negative, while all oxacillin-resistant strains were mecA-positive instead. Only one strain was mecA-positive in 7 oxacillin-intermediate S. aureus strains.

CONCLUSIONOxacillin-resistance in S. aureus isolates was low, and mecA-PCR method is a good choice for rapid examination oxacillin-resistant strains.

Anti-Bacterial Agents ; pharmacology ; Bacterial Proteins ; genetics ; isolation & purification ; Cefotaxime ; pharmacology ; Ceftriaxone ; pharmacology ; Child ; Child, Preschool ; China ; Drug Resistance, Bacterial ; genetics ; Erythromycin ; pharmacology ; Humans ; Latex Fixation Tests ; Methicillin Resistance ; genetics ; Methicillin-Resistant Staphylococcus aureus ; drug effects ; Microbial Sensitivity Tests ; Oxacillin ; pharmacology ; Penicillin-Binding Proteins ; Penicillins ; pharmacology ; Polymerase Chain Reaction ; Staphylococcal Infections ; drug therapy ; microbiology ; Staphylococcus aureus ; drug effects ; genetics ; isolation & purification ; Vancomycin ; pharmacology

BACKGROUNDAmpC beta-lactamases and extended-spectrum beta-lactamases (ESBLs) are becoming predominant causes of resistance to third and forth-generation cephalosporins in Klebsiella pneumoniae (K. pneumoniae). It is very difficult to treat infectious diseases caused by multidrug-resistant K. pneumoniae. The purpose of the present study was to investigate transconjugation and characteristics of beta-lactamase genes in K. pneumoniae producing AmpC beta-lactamases and ESBLs.

METHODSAmpC beta-lactamases were detected by three-dimension test and ESBLs by disc confirmatory test. Minimum inhibitory concentrations (MICs) were determined by agar dilution. Transfer of resistance to EC600 (Rif(r)) was attempted by conjugation in broth and screened on agar containing cefotaxime (2 microg/ml) plus rifampin (1024 microg/ml). The genes encoding AmpC or ESBLs and their transconjugants were detected by PCR and verified by DNA sequencing.

RESULTSThe resistant rates to ampicillin and piperacillin were 100% in 18 isolates of K. pneumoniae. However, imipenem was still of great bactericidal activity on K. pneumoniae, and its MIC(50) was 0.5 microg/mL. Eleven beta-lactamase genes, including TEM-1, TEM-11, SHV-13, SHV-28, CTX-M-9, CTX-M-22, CTX-M-55, OXA-1, LEN, OKP-6 and DHA-1, were found from 18 isolates. And at least one beta-lactamase gene occurred in each isolate. To our surprise, there were six beta-lactamase genes in the CZ04 strain. Among 18 isolates of K. pneumoniae, the partial resistant genes in 8 isolates were conjugated successfully, which had 100% homological sequence with donors by sequence analysis. Compared with donors, 8 transconjugants had attained resistance to most beta-lactams, including ampicillin, piperacillin, cefoxitin, cefotaxime and aztreonam, or even amikacin and gentamicin.

CONCLUSIONSR plasmids can be easily transferred between the resistant and sensitive negative bacilli. It is very difficult to block and prevent the spread of antimicrobial resistance. So more attention should be paid to reducing the frequency, times and dosage of antimicrobials, especially third or fourth cephalosporins.

Ampicillin ; pharmacology ; Anti-Bacterial Agents ; pharmacology ; Bacterial Proteins ; genetics ; physiology ; Cefotaxime ; pharmacology ; Conjugation, Genetic ; genetics ; physiology ; Drug Resistance, Multiple, Bacterial ; genetics ; Genotype ; Imipenem ; pharmacology ; Klebsiella pneumoniae ; drug effects ; genetics ; Microbial Sensitivity Tests ; Piperacillin ; pharmacology ; Plasmids ; genetics ; physiology ; Rifampin ; pharmacology ; beta-Lactamases ; genetics ; physiology

OBJECTIVETo construct prokaryotic expression systems of TCS genes comD/comE/comC of Streptococcus pneumoniae, and to determine the correlation of ComD and ComC with the drug resistance.

METHODSThe entire comD, comE and comC genes were amplified by PCR and their prokaryotic expression systems were established by routine genetic engineering technique. SDS-PAGE and Bio-Rad Agarose Image Analyzor was applied to measure the outputs of target recombinant proteins rComD, rComE and rComC. Rabbits were immunized with these recombinant proteins to prepare antisera. The resistance of S.pneumoniae strains to penicillin and cefotaxime was examined after ComD and ComC were blocked by antisera.

RESULTCompared with the reported sequences, similarities of nucleotide and amino acid sequences of the cloned comD, comE and comC genes were 98.4% approximately 99.3% and 99.1% approximately 100%, respectively. The constructed engineering bacteria E.coli BL21DE3(pET42a-comD), E.coli BL21DE3(pET42a-comE) and E.coli BL21DE3(pET42a-comC) were able to efficiently express the target recombinant proteins and the outputs of rComD, rComE and rComC were 28%, 25% and 35% of the total bacterial proteins, respectively. The double immunodiffusion titers of rabbit antisera against rComD, rComE or rComC were 1:4, 1:4 and 1:8, respectively. After the ComD and/or ComC were blocked by the antisera, the cefotaxime-sensitive S. pneumoniae strains became to resistant to antibiotics but there were no changes for cefotaxime-resistant strains and resistance to penicillin for all tested strains.

CONCLUSIONThe prokaryotic expression systems of S.pneumoniae comD/come/comC genes have been successfully constructed, and the study also indicates that both the ComD and ComC are involved in the drug resistance of S. pneumoniae to cefotaxime.

Animals ; Bacterial Proteins ; biosynthesis ; genetics ; Cefotaxime ; pharmacology ; Escherichia coli ; genetics ; metabolism ; Rabbits ; Recombinant Proteins ; biosynthesis ; genetics ; Recombination, Genetic ; Signal Transduction ; Streptococcus pneumoniae ; drug effects ; genetics ; beta-Lactam Resistance ; genetics

OBJECTIVETo investigate the antibiotics-resistance type and molecular epidemiology of Streptococcus pneumoniae isolated from children in Hangzhou.

METHODSThe sensitivities of 323 strains of Streptococcus pneumoniae to 9 antibiotics were determined in vitro by Kirby-Bauer diffuse methods, and MICs of penicillin and cefotaxime were determined by E-test methods.

RESULTSAmong all 323 strains isolated from children during the period from August 2001 to July 2002, 136 strains (42.1%) were sensitive to penicillin, while 57 strains (17.7%) were penicillin-resistant. Penicillin MICs ranged from 0.012 microg/ml to 4.0 microg/ml. All the strains were sensitive to cefotaxime and its MICs ranged from 0.012 microg/ml to 4.0 microg/ml. The most resistant antibiotic was erythromycin and it's resistant-rate was as high as 90.7%, followed by tetracycline (87.6%), trimethoprim-sulfamethoxazole (48.6%) and chloromycetin (14.9%). Totally 197 strains (61.0%) were multi-drug-resistant pneumococci and most of them were resistant to trimethoprim-sulfamethoxazole, erythromycin and tetracycline at the same time. Two strains (0.6%) were resistant to rifampin and none was resistant to vancomycin and ofloxacin. BOX PCR typing was carried out and no overwhelming fingerprinting pattern was found among penicillin resistant Streptococcus pneumoniae strains which were isolated from patients, while the banding patterns were always similar or identical among the strains isolated from the same specimen or from the same patient at different time, respectively.

CONCLUSIONThe antibiotics-resistant rate of pneumococci was high in Hangzhou, but the third-generation cephalosporins were still the best antibiotics against Streptococcus pneumoniae. One child could be infected or colonized by more than one pneumococci clone at the same or different time.

Anti-Bacterial Agents ; pharmacology ; therapeutic use ; Cefotaxime ; pharmacology ; therapeutic use ; Child, Preschool ; China ; Chloramphenicol ; pharmacology ; therapeutic use ; Drug Resistance, Bacterial ; drug effects ; Erythromycin ; pharmacology ; therapeutic use ; Female ; Humans ; Infant ; Male ; Microbial Sensitivity Tests ; Ofloxacin ; pharmacology ; therapeutic use ; Penicillins ; pharmacology ; therapeutic use ; Pneumococcal Infections ; drug therapy ; microbiology ; Respiratory Tract Infections ; drug therapy ; microbiology ; Rifampin ; pharmacology ; therapeutic use ; Streptococcus pneumoniae ; classification ; drug effects ; isolation & purification ; Tetracycline ; pharmacology ; therapeutic use ; Trimethoprim ; pharmacology ; therapeutic use