Antimicrobial resistance surveillance can provide information needed for empirical therapy of antimicrobial agents and for control of resistance. To determine the trend of antimicrobial resistance in Korea, in vitro susceptibility data in 1998 were collected from 25 hospitals participating to a program of Korean Nationwide Surveillance of Antimicrobial Resistance (KONSAR). The data were analyzed based upon hospital location and bed capacity. The results showed that cefoxitin-resistant E. coli and K. pneumoniae and 3rd-generation cephalosporin-resistant K. pneumoniae were prevalent, that 3rd-generation cephalosporin-resistant E. cloacae, S. marcesens and A. baumannii had increased, and ampicillin-resistant S. enterica were not rare. Oxacillin-resistant S. aureus, penicillin-non-susceptible pneumococci and beta-lactamase-producing H. influenzae were prevalent even smaller hospitals surveyed, and an increase of imipenem-resistant P. aeruginosa and vancomycin-resistant E. faecium is a new obvious threat. In general, resistance rates to some old antimicrobial agents, i.e., E. coli to ampicillin and S. aureus to oxacillin were high and did not vary greatly between the different levels of hospitals, while the rates to some of the newer ones, i.e., P. aeruginosa to imipenem, was quite variable and depended on the hospitals, probably reflecting difference in selective pressure.
Ampicillin/pharmacology ; Anti-Infective Agents, Fluoroquinolone/pharmacology ; Bacteria/drug effects* ; Cephalosporins/pharmacology ; Drug Resistance, Microbial* ; Human ; Korea ; Time Factors

Objective: To investigate the epidemiological characteristics of Yersinia enterocolitica in patients with diarrhea in Pudong New Area, Shanghai. Methods: Active surveillance of diarrhea was conducted in 14 sentinel hospitals (three tertiary-level hospitals, nine secondary-level hospitals, and two primary-level hospitals) from January 2013 to December 2019 in Pudong New Area of Shanghai, China base on their location, catchment area, and patient volume. Cold enrichment method was used to isolate Y. enterocolitica and further detection of bioserotype, virulence genes and antimicrobial susceptibility of the isolates were conducted. The difference of rates was determined using chi-square test or Fisher's exact test. Results: A total of 12 941 diarrhea cases were included, and 0.7% (88/12 941) cases were confirmed with Yersinia enterocolitica infection. 67.0% (59/88) cases were single infection, 33.0% (29/88) cases were mixed infections. Detection rates of Y. enterocolitica increased annually (0.3%-1.2%) and were highest in children<5 years of age (1.1%, 37/3 218) and in spring (1.1%, 32/2 998) (χ² were 18.64 and 9.76, respectively, P<0.05). 58.0% (51/88) cases had watery diarrhea, 15.9% (14/88) had fever and 14.8% (13/88) had vomiting. The predominant bioserotypes were 3/O:3 (53.4%, 47/88), followed by 1A/O:8 (15.9%, 14/88) and 1A/O:5(6.8%, 6/88), respectively. Bioserotype 3/O:3 counted for the highest proportions (89.2%, 33/37) in children <5 years of age. All the strains of bioserotype 3/O:3 harbored ail, ystA, yadA and virF genes, which encoded pathogenic Y. enterocolitica. 11/14 strain of 1A/O:8 and 4/6 strains of 1A/O:5 harbored ystB gene. Most strains were resistant to ampicillin (80.7%,71/88) and amoxicillin/clavulanic acid (71.6%,63/88), and 63.8% (56/88) strains were multidrug resistance (MDR). The difference of antimicrobial resistance rates between 3/O:3 and non 3/O:3 was statistically significant in ampicillin, cefoxitin, nalidixic acid, tetracycline and ampicillin/sulbactam (χ² was 14.68, 43.80, 41.86, 30.54 and 5.07, respectively, P<0.05). Conclusion: The detection rate of Yersinia enterocolitica was higher in children than in adults in Pudong New Area , Shanghai. The predominant bioserotype was pathogenic 3/O:3 with multidrug resistance.
Ampicillin ; Anti-Bacterial Agents/pharmacology* ; Child ; China/epidemiology* ; Diarrhea/epidemiology* ; Humans ; Yersinia enterocolitica

Conjugal plasmid pGH112 has been developed based on the replicons of Streptomyces coelicolor plasmid SCP2 and E. coli ColE. The plasmid contains ampicilin resistance gene(amp) for selection in E. coli and thiostrepton resistance gene (tsr) for selection in Streptomycetes, and a 0.76 kb oriT fragment of (IncP) RK2. Conjugal transfer of pGH112 was performed from E. coli to S. coelicolor A3(2), S. avermitilis, S. lividans TK54, S. toxytricini NNRL15443, S. venezuelae ISP5230 and Sacc. erythraea by conjugation, results show that the plasmid was able to transfer efficenctly from E. coli to Streptomycetes, was stably inherited in the recipients. pGH113 was constructed from pGH112 by combining the constitutive ermE promoter with green fluorescent protein gene(gfp).
Ampicillin Resistance ; genetics ; Conjugation, Genetic ; Escherichia coli ; genetics ; Green Fluorescent Proteins ; genetics ; Plasmids ; Streptomycetaceae ; genetics ; Thiostrepton ; pharmacology

OBJECTIVETo analyze the infection status and the drug resistance of enterococci in patients with severe hepatitis to guide future treatment.

METHODSAll bacteria from infected patients with severe hepatitis were cultured with BacT/Alert120 automation instrument (Aksu) and identified with Vitek-AMS60 (Biomerieux). Drug sensitivities of the isolated enterococci were tested with 11 antibacterial agents.

RESULTSAmong the 112 isolated enterococci, Enterococcus faecalis was the most preponderant bacterium, and the second was E. faecium. Their isolation rates were 79.5% and 14.3%, respectively. 57.1% of all the enterococci were found in the ascetic fluid of patients with severe hepatitis. Fifty-eight (51.8%) isolated enterococci were found to be high level aminoglycoside resistant (HLAR), 19 (17.0%) enterococci were ampicillin-resistant enterococcus (ARE) and 7 (6.3%) were both HLAR and ARE. The susceptive rates of the enterococci to vancomycin and teicoplanin were very high, namely 96.4% and 100%, respectively. No vancomycin or teicoplanin resistant enterococci were found, but 4 enterococci were mildly sensitive to vancomycin.

CONCLUSIONEnterococcus faecalis is the most prevalent species isolated in severe hepatitis patients infected with enterococcal infection. From our study, vancomycin and teicoplanin are the drugs of first choice to treat those infections.

Aminoglycosides ; pharmacology ; Ampicillin Resistance ; Drug Resistance, Bacterial ; Enterococcus faecalis ; drug effects ; Gram-Positive Bacterial Infections ; complications ; microbiology ; Hepatitis ; microbiology ; Humans ; Microbial Sensitivity Tests ; Teicoplanin ; pharmacology ; Vancomycin ; pharmacology

OBJECTIVETo investigate the effects of putative bacteriocin immunity proteins on the growth mode of Streptococcus mutans (Sm). To observe the differences of antimicrobial sensitivity in planktonic Sm wild-type strains and mutant strains caused by the inactivation of bacteriocin immunity proteins and their influence on the biofilm formation.

METHODSSm wild-type strains (WT) and its knockout mutants defective in immA and immB (ΔimmA(-) and ΔimmB(-) mutants) coding putative bacteriocin immunity proteins were cultured in brain heart infusion (BHI) and selected by erythromycin at the concentration of 10 mg/L. Optical density was detected by spectrophotometer every hour and growth curve was drawn. WT, ΔimmA(-) and ΔimmB(-) mutants were treated with ampicillin (0.04, 0.05, 0.06, 0.07, 0.08 mg/L), sodium fluoride (50, 100, 150, 200, 250 mg/L) and sodium hypochlorite (0.078%, 0.156%, 0.313%, 0.625%, 1.250%) for 24 hours. Optical density was detected by multifunctional micro plate reader. WT and the mutants were cultured in MBEC(TM) P&G Assay for 24 hours. The minimum biofilm eradication concentration (MBEC) of chlorhexidine against Sm was determined by serial dilution method. Confocal laser scanning microscopy (CLSM) was used to visualize the biofilm architecture, depth and ratio of live to dead bacteria.

RESULTSGrowth curve showed that it took about 3 hours to reach exponential phase and about 7 hours to stationary phase for WT, while 4 hours to exponential phase and 8 hours to stationary phase for mutants. Optical density of mutants were lower than WT in the presence of various antimicrobial agents (P < 0.01). In 0.06 mg/L ampicillin group, optical density value of WT, ΔimmA(-) and ΔimmB(-) mutants were 0.334 ± 0.016, 0.027 ± 0.016 and 0.047 ± 0.018. In 150 mg/L sodium fluoride group, optical density value of WT and mutants were 0.254 ± 0.018, 0.129 ± 0.011 and 0.167 ± 0.010. In 0.313% sodium hypochlorite group, optical density value of WT and mutants were 0.467 ± 0.008, 0.017 ± 0.006 and 0.050 ± 0.006. The MBEC of chlorhexidine against Sm WT, ΔimmA(-) and ΔimmB(-) mutants were 6.25, 1.57, and 3.13 mg/L. The results by CLSM showed a noticeable difference in biofilm architecture. The depth of WT biofilm was higher than the mutants biofilm (P < 0.01). The ratio of live to dead bacteria of WT biofilm was higher than ΔimmA(-) mutants in all layers (P < 0.05) and ΔimmB(-) mutants in the outer and intermedium layer (P < 0.01). There is no significant different between the inner layers of WT and ΔimmB(-) mutants (P = 0.191).

CONCLUSIONSPutative bacteriocin immunity proteins have influence on the growth mode of Sm. The antimicrobial sensitivity of planktonic Sm can be up-regulated by the inactivation of immA or immB. The MBEC of chlorhexidine against ΔimmA(-) and ΔimmB(-) mutants is lower than WT. The inactivation of immA or immB affects the biofilm formation.

Ampicillin ; pharmacology ; Anti-Bacterial Agents ; pharmacology ; Bacteriocins ; genetics ; immunology ; Biofilms ; drug effects ; growth & development ; Cariostatic Agents ; pharmacology ; Chlorhexidine ; pharmacology ; Disinfectants ; pharmacology ; Microbial Sensitivity Tests ; Mutation ; Plankton ; drug effects ; Sodium Fluoride ; pharmacology ; Sodium Hypochlorite ; pharmacology ; Streptococcus mutans ; drug effects ; genetics

The aim of this study is to characterize the epidemiological features of typhoid fever, categorized as class 1 notifiable disease in Korea and to analyze the recent change of antimicrobial resistance of Salmonella enterica serotype Typhi isolated nationwide. We retrospectively analyzed the 1,692 culture-proven cases from 1992 to 2000, using the data of the Korean National Institute of Health. The overall incidence of culture-proven typhoid fever was 0.41 per 100,000 population. It occurred all over the country, but the southeastern part of Korean peninsula had the higher incidence rate than other areas. There were several outbreaks suspected, of which two outbreaks were confirmed. The resistance rate against chloramphenicol showed mild increase, but the ampicillin, trimethoprim/sulfamethoxazole, kanamycin, or nalidixic acid resistance remained at the similar levels for the past 9 yr. There were 21 (1.3%) multidrug-resistant (MDR) strains isolated since 1992, and the number of those has increased. Two strains resistant to ciprofloxacin were first identified in Korea.
Ampicillin/pharmacology ; Anti-Bacterial Agents/pharmacology ; Chloramphenicol/pharmacology ; *Drug Resistance, Microbial ; Drug Resistance, Multiple ; Human ; Kanamycin/pharmacology ; Korea ; Nalidixic Acid/pharmacology ; Retrospective Studies ; Salmonella Infections/*epidemiology ; Salmonella enterica/*metabolism ; Seasons ; Serotyping ; Support, Non-U.S. Gov't ; Time Factors ; Trimethoprim/pharmacology

AIMTo design and synthesize new oxazolidinone antibacterial agents.

METHODSThe synthetic method reported in literature has been modified and new 3,5-disubstituted oxazolidinone compounds were synthesized on the basis of SAR reported in the literature and their antibacterial activities in vitro were determined.

RESULTSEighteen new objective compounds were synthesized, and their structures were determined by IR, 1HNMR and FAB-MS. Within the eighteen new objective compounds, sixteen compounds showed antibacterial activity in vitro and compound 9, 10 and 10b showed better antibacterial activities in vitro than ciprofloxacin (CIP), sultamicillin (Sul) and vancomycin (VCO). Compounds 9a and 11c have no antibacterial activity in vitro at all.

CONCLUSIONCompounds 9, 10 and 10b are worthy to be intensively studied.

Ampicillin ; pharmacology ; Anti-Bacterial Agents ; chemical synthesis ; chemistry ; pharmacology ; Ciprofloxacin ; pharmacology ; Microbial Sensitivity Tests ; Molecular Structure ; Oxazolidinones ; chemical synthesis ; chemistry ; pharmacology ; Staphylococcus aureus ; drug effects ; Streptococcus ; drug effects ; Structure-Activity Relationship ; Sulbactam ; pharmacology ; Vancomycin ; pharmacology

Changes in udder health and antibiotic resistance of mastitis pathogens isolated from dairies upon conversion from conventional to organic management over a 3-year period was studied. Coagulase-negative staphylococci (CNS) were the most prevalent mastitis pathogens isolated. CNS were significantly less resistant to beta-lactam antibiotics when isolated from milk after the herd transitioned to organic management. Cessation of the use of antimicrobial therapies in dairies in combination with organic management could lead to a reduction in the antimicrobial resistance of mastitis pathogens.
Ampicillin/pharmacology ; Animals ; Anti-Bacterial Agents/pharmacology ; Cattle ; Cephalothin/pharmacology ; Cloxacillin/pharmacology ; Drug Resistance, Microbial ; Female ; Lactation ; Mastitis, Bovine/*microbiology ; Microbial Sensitivity Tests ; Organic Agriculture ; Penicillins/pharmacology ; Prevalence ; Staphylococcal Infections/microbiology/*veterinary ; Staphylococcus/*drug effects/*isolation & purification

BACKGROUNDIncreasing prevalence of Staphylococcus aureus (S. aureus), particularly methicillin-resistant S. aureus (MRSA) has been reported in China. In this study, we investigated the drug resistance characteristic, genetic background, and molecular epidemiological characteristic of S. aureus in Changsha.

METHODSBetween January 2006 and December 2008, 293 clinical isolates of S. aureus were collected from 11 hospitals in Changsha and identified by the Vitek-2 system. All the isolates were verified as MRSA by PCR amplification of both femA and mecA genes. K-B disk method was used to test drug sensitivity of S. aureus to antibiotics. Pulsed-field gel electrophoresis (PFGE) was performed for genotypic and homologous analysis of 115 isolates randomly selected from the original 293 clinical S. aureus isolates.

RESULTSS. aureus was highly resistant to penicillin, ampicillin, erythromycin, and clindamycin with resistant rates of 96.6%, 96.6%, 77.1%, and 67.2% respectively. All the isolates were susceptible to tecoplanin, vancomycin, and linezolid. MRSA accounted for 64.8% (190/293) of all the S. aureus strains. The 115 S. aureus isolates were clustered into 39 PFGE types by PFGE typing, with 13 predominant patterns (designated types A to M) accounting for 89 isolates. The most prevalent PFGE type was type A (n = 56, 48.7%) and 100.0% of type A strains were MRSA. PFGE type A included 13 subtypes, and the most prevalent subtype was subtype A1 (46.4%, 26/56). Strains with PFGE type A were isolated from eight hospitals (8/11), and both subtypes A1 and A4 strains were isolated in a university hospital.

CONCLUSIONSClinical isolates of S. aureus in Changsha were resistant to multiple traditional antibiotics. There was an outbreak of PFGE type A MRSA in this area and the A1 subtype was the predominant epidemic clone. Dissemination of the same clone was an important reason for the wide spread of MRSA.

Ampicillin ; pharmacology ; Anti-Bacterial Agents ; pharmacology ; China ; Clindamycin ; pharmacology ; Electrophoresis, Gel, Pulsed-Field ; Erythromycin ; pharmacology ; Humans ; Methicillin-Resistant Staphylococcus aureus ; drug effects ; genetics ; Microbial Sensitivity Tests ; Penicillins ; pharmacology ; Staphylococcus aureus ; drug effects ; genetics ; Vancomycin ; metabolism

OBJECTIVETo study the inducible antibacterial activity of the hemolymph from housefly larva and analyze the antibacterial molecules.

METHODSThe hemolymph was collected from the third instar housefly larvae 48 h after pricking treatment. Nine standard bacterial strains were used for determination of the antibaterial activity of the collected hemolymph and its combination with ampicillin. The anti-yeast activity of the hemolymph and its mixture with fluconazol was also assayed. The antibacterial molecules in the hemolymph was analyzed by SDS-PAGE.

RESULTSThe growth of E.coli, Staphylococcus aureus, Staphylococcus albus, subserotypes of Shigeila flexneri, Bacillus proteus, Bacillus subtilis, Bacillus typhi, Bacillus paratyphosus, and Micrococcus lysodeikticus could be inhibited by the hemolymph collected from housefly larva, and the effect differed significantly between the groups (Plt;0.001). The hemolymph produced the strongest antibacterial activity against Micrococcus lysodeikticus, and the combination of the hemolymph with ampicillin most conspicuously inhibited the growth of Staphylococcus albus. The hemolyph and fluconazol exhibited obvious synergistic effect against yeast. SDS-PAGE identified some specific antibacterial molecules in the hemolymph.

CONCLUSIONThe induced hemolymph from housefly larva possesses strong antibacterial and antifungal activities especially against Micrococcus lysodeikticus. The hemolymph in combination with ampicillin produces the strongest effect against Staphylococcus albus, and fluconazol can significantly enhance the anti-yeast activity of the hemolymph through a synergistic mechanism.

Ampicillin ; pharmacology ; Animals ; Anti-Bacterial Agents ; pharmacology ; Antifungal Agents ; pharmacology ; Bacteria ; drug effects ; Electrophoresis, Polyacrylamide Gel ; Fluconazole ; pharmacology ; Hemolymph ; immunology ; Houseflies ; immunology ; Larva ; immunology ; Microbial Sensitivity Tests ; Yeasts ; drug effects