BACKGROUND: Extended-spectrum cephalosporins and fluoroquinolones are important antimicrobials for treating invasive salmonellosis, and emerging resistance to these antimicrobials is of paramount concern. METHODS: A total of 30 Salmonella spp. clinical isolates recovered in Gyeongsangbuk-do from 2012 to 2013 were characterized using antibiotic resistance profiles and pulsed-field gel electrophoresis (PFGE). RESULTS: A high prevalence of multidrug-resistant isolates, mainly showing an ampicillin, nalidixic acid, chloramphenicol resistance pattern, was observed. Four extended-spectrum beta-lactamase (ESBL)-producing isolates (3 CTX-M-15 isolates and 1 CTX-M-27 isolate) were found. The bla(CTX-M-27) gene was carried by an IncF conjugative plasmid in the S. Infantis isolate. The bla(CTX-M-15) gene were carried by an IncF (2 isolates) or IncHI2 (1 isolate) conjugative plasmid in S. Enteritidis. In addition, a single mutation of GyrA, Ser83Thr (1 isolates), Asp87Tyr (9 isolates), Asp87Gly (4 isolates), and Asp87Leu (3 isolates), was detected in nalidixic acid-resistant Salmonella spp. isolates. XbaI PFGE analysis of all isolates revealed more than 19 different pulsotypes. The most common S. Enteritidis PFGE pattern (SEGX01.003) was associated with a larger number of cases of invasive salmonellosis than all other patterns. CONCLUSION: The information from our study can assist in source attribution, outbreak investigations, and tailoring of interventions to maximize disease prevention.
Ampicillin ; beta-Lactamases ; Cephalosporins ; Chloramphenicol Resistance ; Drug Resistance ; Drug Resistance, Microbial ; Electrophoresis, Gel, Pulsed-Field ; Fluoroquinolones ; Gyeongsangbuk-do ; Nalidixic Acid ; Plasmids ; Prevalence ; Salmonella Infections ; Salmonella*

Ninety-two strains of Serratia marcescens isolated from 5 hospitals were analyzed for plasmid profile, antimicrobial drug resistance pattern, biotyping, and production of pigment. Ninety-three percents of strains were resistant to chloramphenicol (Cm), tetracycline (Tc), sulfisoxazole (Su), cefazolin (Cz), ampicillin (Ap), and rifampin (Rf). A majority of strains were susceptible to amikacin (Ak), ciprofloxacin (Ci), and cefotaxim (Ct). Fifty-four resistance patterns were found in 94 strains and the most prevalent resistance pattern was CmTcSuApCzRf. Seventeen (17.4%) isolates could transfer their partial resistance to E. coli or Klebsiella pneumoniae by conjugation. Twenty-seven plasmid profiles in 54 strains (58.7%) were detected, however no predominant patterns were seen in isolates from each hospital. Eleven biotypes were detected. The common types were A3b (29.4%) and A8b (27.1%), predominant types were found in each hospital. Twenty strains from 4 of 5 hospitals showed consistence of 3 types. These results indicate that plasmid profile analysis, Grimont biotyping, and resistance pattern type of strains in combination are useful as an epidemiological tool for S. marcescens isolates and some of isolates were confirmed as nosocomial strains.
Amikacin ; Ampicillin ; Cefazolin ; Cefotaxime ; Chloramphenicol ; Ciprofloxacin ; Drug Resistance, Microbial ; Epidemiologic Studies* ; Klebsiella pneumoniae ; Plasmids ; Rifampin ; Serratia marcescens* ; Serratia* ; Sulfisoxazole ; Tetracycline

The frequency of antibiotic resistance among Salmonella enterica serovar Typhimurium has increased due to the transfer of multiple resistance factors. We detected the 13 antibiotic resistance genes by multiplex-PCR and compared with the results of phage typing and antibiotic disk diffusion for 49 S. typhimurium isolated from food-poisoning outbreaks in Seoul from 1999 to 2002. Resistance genes for tetracycline, streptomycin, ampicillin, sulfonamide, amino-glycoside-modifying enzyme, chloramphenicol, kanamycin, and trimethoprim were detected in 67.3%, 57.1%, 26.5%, 8.1%, 8.1%, 5%, 2.0%, and 0% of isolates, respectively. Overall 28 isolates (57.1%) possessed two or more antibiotic resistance genes. Class 1 integron carrying multidrug resistace genes, ant(3")-IaB, blaPSE, qacE delta1/sul, and tet G were amplified especially in only DT104 isolates. Among the related resistance genes for same antibiotics, strA and strB for streptomycin resistance were simultaneously detected but tetA and tetB for tetracycline were sporadically detected. DT 104 isolates contained only aadA2 and tetG.
Ampicillin ; Anti-Bacterial Agents ; Bacteriophage Typing ; Chloramphenicol ; Diffusion ; Disease Outbreaks ; Drug Resistance, Microbial ; Humans ; Integrons ; Kanamycin ; R Factors ; Salmonella enterica* ; Salmonella* ; Seoul* ; Streptomycin ; Tetracycline ; Trimethoprim

Multiple-antibiotic-resistance (Mar) mutants were prepared from the wild-type Escherichia coli K-12 MC4100 or W3110, were analyzed for the antibiotic resistance by minimal inhibitory concentration (MIC), and compared with their isogenic parent strains and E. coli clinical isolates. Mutation frequency was approximately 10-7 to 10-9 MIC levels of chloramphenicol (Cm), ampicillin (Ap), tetracycline (Tc), or ciprofloxacin (Cp) antibiotics against E. coli Mar mutants were 50 ug/ml, 300 ug/ml, 200 ug/ml, or 30 ug/ml, respectively, at their highest MIC levels. Cross-resistances of each Mar mutants against Cm, Ap, Tc, Cp, erythromycin (Em), nalidixic acid (Na), and rifampin (Rf) were evaluated. Almost all of Mar mutants showed approximately 9 to 140-fold increase of MIC with contrast to the MIC of isogenic parent strains and E. coli clinical isolates, except Rf antibiotics. The induction multiplicity of Mar mutants by salicylate (SAL) was approximately the same, 2 to 10-fold, and 2 to 25-fold increase of MIC, in case of E. coli clinical isolates, Mar mutants derived from MC4100, and W3110, respectively.
Ampicillin ; Anti-Bacterial Agents ; Chloramphenicol ; Ciprofloxacin ; Drug Resistance, Microbial* ; Erythromycin ; Escherichia coli* ; Escherichia* ; Humans ; Mutation Rate ; Nalidixic Acid ; Parents ; Rifampin ; Tetracycline

BACKGROUND: Group A streptococcus (Streptococcus pyogenes) is the most common cause of bacterial pharyngitis and an important cause of a variety of suppurative and nonsuppurative diseases. The molecular genetic analysis of group A streptococci in clinical isolates is rarely reported in Korea. In this study, molecular genetic analysis using serotyping and emm sequence analysis, testing the presence of the SpeA and SpeB gene, and the determination of an antimicrobial resistance pattern were investigated. METHODS: Sixty nine strains of S. pyogenes from clinical isolates in Korea during 1999-2002 were examined by T agglutination, serum opacity reaction, and emm sequence analysis. Also investigated were antimicrobial susceptibility and the frequency of SpeA and SpeB genes. RESULTS: The antibiotic resistance rates for S. pyogenes isolates were shown at 28.9% of erythromycin, 14.2% of ampicillin, 9.5% of chloramphenicol, and 6.3% of levofloxacin. However, all strains were susceptible to penicillin, vancomycin, and teicoplanin. By T agglutination typing, forty-one (59.4%) among sixty-nine isolates were identified as T28 (13%), T6 (13%), T1 (10%), T12 (8.7%), T4 (4%), T5/27/44 (4%), T3/B3264 (2.9%), T11/12 (1.4%), and TB3264 (1.4%). Thirty-five (50.7%) among sixty nine isolates were positive in serum opacity reaction. The SpeB gene showed positive in all strains but the SpeA gene in eleven (15.9%) strains. By emm gene sequence analysis, forty-seven (68.1%) CONCLUSIONS: Our data showed that antimicrobial resistance of clinical isolates to erythromycin were higher than those reported from the United States and Europe, and emm genotyping could be used for a reliable and efficient typing method.
Agglutination ; Ampicillin ; Chloramphenicol ; Drug Resistance, Microbial ; Erythromycin ; Europe ; Korea ; Levofloxacin ; Molecular Biology* ; Penicillins ; Pharyngitis ; Sequence Analysis ; Serotyping ; Streptococcus ; Streptococcus pyogenes* ; Teicoplanin ; United States ; Vancomycin

BACKGROUND: Nontyphoid Salmonella (NTS) is a leading cause of human food-borne enteritiS. It has been known that integron, a naturally occurring gene capture and expression element, plays an important role in the development and dissemination of multidrug-resistance. In this study, we investigated the prevalences and molecular characteristics of integrons in NTS clinical strains. MATERIALS AND METHODS: Between 1995-96 and 2000-03, a total 261 NTS clinical strains comprising 39 serotypes were collected from clinical specimens. All strains were serotyped, and the MICs of ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, tetracycline, and trimethoprim were determined by agar dilution method. Integrons were detected by PCR amplification of integrase genes, and gene cassettes were determined by PCR and sequencing. Conjugation experiments were performed using E. coli J53 as a recipient. The clonal relationship was analyzed by pulsed-field gel electrophoresis (PFGE). RESULTS: Of the 261 strains tested, class 1 integrons were present in 21 strains (8.0%). Class 2 and class 3 integrons were not found. The integron-positive rate was higher in S. Typhimurium (24.2% [8/33]) than in S. Enteritidis (2.0% [3/153]). Overall rates of antimicrobial resistance were higher in integron-positive strains. dhfr12-orfF-aadA2 gene cassette was detected in 5 strains, aadA2 in 4 strains, dhfr17-orfF-aadA5 in 2 strains, and addA1 in 1 strain. Ten integron-positive transconjugants were successfully selected. Among 8 integron-positive strains of S. Typhimurium, 7 had similar PFGE patterns. CONCLUSION: This study suggests that integrons are already playing a significant role in antimicrobial resistance in NTS. Continuous monitoring is needed to detect the emergence and spread of integron-mediated antimicrobial resistance.
Agar ; Ampicillin ; Chloramphenicol ; Drug Resistance, Microbial ; Electrophoresis, Gel, Pulsed-Field ; Enteritis ; Humans ; Integrases ; Integrons ; Polymerase Chain Reaction ; Prevalence ; Salmonella ; Sprains and Strains ; Streptomycin ; Sulfamethoxazole ; Tetracycline ; Trimethoprim

The present study was done to scrutinize the possible relation between infective genes and antimicrobial resistance in Enterococcus faecalis and Enterococcus faecium. Considering the fact that the presence of recognized infective determinants among clinical isolates may promote the emergence of infections and persistence of Enterococci in hospital settings, which can lead to an increase in antimicrobial resistance. 175 E. faecalis and 67 E. faecium isolated from clinical specimens were used. The isolates were identified, and then antibiotic susceptibility testing was performed. The MIC of vancomycin and teicoplanin were determined by broth microdilution method. The presence of infective genes esp, hyl and asa₁ was scrutinized using PCR. Of the 280 enterococcal isolates, 175 (62.5%) isolates were identified as E. faecalis, 67 (24%) as E. faecium and 38 (13.5%) as Enterococcus spp. The results of the antibiotic susceptibility testing showed resistance rates of 5% and 73% to vancomycin and teicoplanin in E. faecalis and E. faecium isolates, respectively. The statistical analysis showed that the esp infective gene has significant associations with ciprofloxacin, erythromycin and tetracycline in E. faecium and with chloramphenicol in E. faecalis strains; the hyl with teicoplanin and vancomycin in E. faecium strains; and also asa₁ with vancomycin in E. faecium and with ampicillin and chloramphenicol in E. faecalis strains. Regarding the relationships between virulence genes and antibiotic resistance in strains of E. faecalis and E. faecium, detection of infective factors associated with invasive diseases has become a major issue of concern.
Ampicillin ; Anti-Bacterial Agents ; Chloramphenicol ; Ciprofloxacin ; Drug Resistance, Microbial ; Enterococcus ; Enterococcus faecalis ; Enterococcus faecium ; Erythromycin ; Iran ; Methods ; Polymerase Chain Reaction ; Teicoplanin ; Tetracycline ; Vancomycin ; Virulence

BACKGROUND: Nontyphoid Salmonella (NTS) is a leading cause of human food-borne enteritiS. It has been known that integron, a naturally occurring gene capture and expression element, plays an important role in the development and dissemination of multidrug-resistance. In this study, we investigated the prevalences and molecular characteristics of integrons in NTS clinical strains. MATERIALS AND METHODS: Between 1995-96 and 2000-03, a total 261 NTS clinical strains comprising 39 serotypes were collected from clinical specimens. All strains were serotyped, and the MICs of ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, tetracycline, and trimethoprim were determined by agar dilution method. Integrons were detected by PCR amplification of integrase genes, and gene cassettes were determined by PCR and sequencing. Conjugation experiments were performed using E. coli J53 as a recipient. The clonal relationship was analyzed by pulsed-field gel electrophoresis (PFGE). RESULTS: Of the 261 strains tested, class 1 integrons were present in 21 strains (8.0%). Class 2 and class 3 integrons were not found. The integron-positive rate was higher in S. Typhimurium (24.2% [8/33]) than in S. Enteritidis (2.0% [3/153]). Overall rates of antimicrobial resistance were higher in integron-positive strains. dhfr12-orfF-aadA2 gene cassette was detected in 5 strains, aadA2 in 4 strains, dhfr17-orfF-aadA5 in 2 strains, and addA1 in 1 strain. Ten integron-positive transconjugants were successfully selected. Among 8 integron-positive strains of S. Typhimurium, 7 had similar PFGE patterns. CONCLUSION: This study suggests that integrons are already playing a significant role in antimicrobial resistance in NTS. Continuous monitoring is needed to detect the emergence and spread of integron-mediated antimicrobial resistance.
Agar ; Ampicillin ; Chloramphenicol ; Drug Resistance, Microbial ; Electrophoresis, Gel, Pulsed-Field ; Enteritis ; Humans ; Integrases ; Integrons ; Polymerase Chain Reaction ; Prevalence ; Salmonella ; Sprains and Strains ; Streptomycin ; Sulfamethoxazole ; Tetracycline ; Trimethoprim

PURPOSE: As the incidence of non-typhoidal salmonella strains resistant to antibiotics has been increased, we attempted to investigate clinical aspects of non-typhoidal salmonella gastroenteritis and antibiotics resistance. METHODS: From January 2000 to June 2002, 99 children with positive stool culture of non-typhoidal salmonella were studied about clinical features, the incidence of antibiotics and multi-drug resistance and the difference of incidence of antibiotics resistance according to immune status. RESULTS: There were 66 males and 33 females. The majority of them were under 5 years of age (71%). 25 children were immunocompromised due to chemotherapy, steroid or immunosuppressive treatment. Serogroup D was the most common isolates (65%) followed by B (16%), C (8%) and E (8%). Resistance rate of 30% to ampicillin, 12% to chloramphenicol, 20% to trimethoprim- sulfamethoxazole (TMP-SMX), 11% to cefotaxime and 8% to cefixime were obtained. All isolates were susceptible to ciprofloxacine. Resistance rate to cefotaxime and cefixime in immunocompromised patients was 24% and 14.3% respectively, which were significantly higher compared to that in immunocompetent patients (6.8%, 5.6%, p<0.05). 11 isolates were resistant to three or more antibiotics. The incidence of multi-drug resistant isolates was significantly higher in immunocompromised patients (24%) than that of immunocompetent patients (6.8%). CONCLUSION: Because of the high prevalence of non-typhoidal salmonella strains resistant to ampicillin, chloramphenicol and TMP-SMX, third-generation cephalosporin might be the treatment of choice in non-typhoidal salmonella gastroenteritis. In particular, antibiotics should be carefully selected in immunocompromised patients because non-typhoidal salmonellas from them showed the higher incidence of antibiotic resistance and multi-drug resistance.
Ampicillin ; Anti-Bacterial Agents* ; Cefixime ; Cefotaxime ; Child ; Chloramphenicol ; Ciprofloxacin ; Drug Resistance, Microbial ; Drug Resistance, Multiple ; Drug Therapy ; Female ; Gastroenteritis* ; Humans ; Immunocompromised Host ; Incidence ; Male ; Prevalence ; Salmonella* ; Sulfamethoxazole ; Trimethoprim, Sulfamethoxazole Drug Combination

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