Forty-seven ampicillin-resistant R plasmids derived from 218 Shigella sonnei isolates from Daegu and Gwangju areas from 1980 to 2000 were epidemiologically compared by fragments of restriction endonuclease patterns by EcoRI and SmaI, and by Southern hybridization with a blaTEM-1 probe. All the ampicillin-resistant strains isolated in the 1980S carried a conjugative R plasmid responsible for multiple resistance other than ampicillin, and an ampicillin-resistance plasmid. Ampicillin-resistant strains isolated in the 1990S harbored single conjugative R plasmid encoding ampicillin resistance along with variable antimicrobial resistances. The restriction endonuclease digestion patterns and Southern hybridiztion analysis of conjugative R plasmids showing identical resistance pattern and a same size showed different fragment and Western blotting patterns according to different isolation years and areas, while identical patterns were observed among the plasmids derived from a same isolation year and area. These findings suggest that ampicillin resistance among S. sonnei isolates was due to introduction of ampicillin-resistant R plasmids originated from different sources.
Ampicillin Resistance* ; Ampicillin* ; Blotting, Western ; Daegu ; Digestion ; DNA Restriction Enzymes ; Gwangju ; Plasmids ; R Factors ; Shigella sonnei* ; Shigella*

BACKGROUND: Enterococcus faecium, especially vancomycin-resistant E. faecium (VREfm), is a major concern for patients with hematologic diseases. Exposure to antibiotics including fluoroquinolone, which is used as a routine prophylaxis for patients with hematologic (MH) diseases, has been reported to be a risk factor for infection with vancomycin-resistant eneterocci. We compared the characteristics of E. faecium isolates according to their vancomycin susceptibility and patient group (MH vs non-MH patients). METHODS: A total of 120 E. faecium bacteremic isolates (84 from MH and 36 from non-MH patients) were collected consecutively, and their characteristics (susceptibility, multilocus sequence type [MLST], Tn1546 type, and the presence of virulence genes and plasmids) were determined. RESULTS: Among the vancomycin-susceptible E. faecium (VSEfm) isolates, resistance to ampicillin (97.6% vs 61.1%) and high-level gentamicin (71.4% vs 38.9%) was significantly higher in isolates from MH patients than in those from non-MH patients. Notably, hyl, esp, and pEF1071 were present only in isolates with ampicillin resistance. Among the VREfm isolates, ST230 (33.3%) and ST17 (26.2%) were predominant in MH patients, while ST17 (61.1%) was predominant in non-MH patients. Plasmid pLG1 was more prevalent in E. faecium isolates from MH patients than in those from non-MH patients, regardless of vancomycin resistance. Transposon analysis revealed five types across all VREfm isolates. CONCLUSIONS: The antimicrobial resistance profiles and molecular characteristics of E. faecium isolates differed according to the underlying diseases of patients within the same hospital. We hypothesize that the prophylactic use of fluoroquinolone might have an effect on these differences.
Ampicillin ; Ampicillin Resistance ; Anti-Bacterial Agents ; Enterococcus faecium* ; Enterococcus* ; Gentamicins ; Hematologic Diseases ; Humans ; Multilocus Sequence Typing ; Plasmids ; Risk Factors ; Vancomycin ; Vancomycin Resistance ; Virulence

OBJECTIVES: To determine the occurrence and antimicrobial resistance of pathogenic vibrios from green mussel, Perna viridis in bacoor bay cavite.

METHODS: Vibrios were isolated using TCBS agar and confirmed using API Identification kit. The relationship between the density of vibrios and environment parameters such as months, harvest sites and other physico-chemical parameters of water was determined. The isolated vibrios were subjected to antibiotic resistance testing to determine the resistance patterns.

RESULTS: Pathogenic vibrios were isolated in all of the 90 mussel samples. Of the 183 vibrio isolates, 75 strains were V. alginolyticus and 53 strains belonged to V. cholerae wherein 18 (34%) of these were V. cholerae serotype O1. Forty nine (49) strains belonged to V. parahaemolyticus and six were V. vulnificus. Using the regression analysis, salinity, water temperature and ph have significant correlation on the density of vibrios (p=0.0309), with regression model, total vibrios = -16990763 + 145858 Salinity + 186808 Temperature + 1037886 pH. In the antimicrobial resistance assay,ampicillin had the highest drug resistance (37.8%) followed by nalidixic acid (10.4%), tetracycline (10.4%) and co-trimoxazole (9.3%).

CONCLUSION: Pathogenic vibrios were isolated in mussel of Bacoor, Cavite and can be predicted using salinity, temperature and pH of the water. Thirty six percent (36%) of Vibrio isolates were resistance to ampicillin.

BACKGROUND: Daptomycin is a novel cyclic lipopeptide antibiotic that exhibits in vitro bactericidal activity against gram-positive pathogens including methicillin-resistant staphylococci and vancomycin-resistant enterococci. The aim of this study is to determine the in vitro activities of daptomycin against recent clinical isolates of methicillin-resistant staphylococci and vancomycin-resistant enterococci in Korea. MATERIALS AND METHODS: A total of 117 clinical strains of methicillin-resistant staphylococci and vancomycin-resistant enterococci were isolated at a tertiary-care hospital in Korea in 2004. Susceptibility to daptomycin was tested by the CLSI broth microdilution method using Mueller-Hinton broth (MHB) which was adjusted to contain a final concentration of 50 microgram/mL of ionized calcium (Ca2+). Susceptibilities to ampicillin, oxacillin, levofloxacin, vancomycin, and linezolid were tested by the CLSI agar dilution method. RESULTS: All isolates of methicillin-resistant S. aureus and coagulase-negative staphylococci were inhibited by 1 microgram/mL of daptomycin, and MIC90s were 1 microgram/mL, which were similar to those of vancomycin and linezolid. MIC90s of daptomycin for vancomycin-resistant E. faecalis and E. faecium were 0.5 microgram/mL and 2 microgram/mL, respectively, and all isolates were susceptible to daptomycin. MIC90s of linezolid and levofloxacin for vancomycin-resistant enterococci were 1-2 microgram/mL and 64 microgram/mL, respectively. Resistance rates of vancomycin-resistant E. faecalis and E. faecium to levofloxacin were 100% and 96%, respectively. Daptomycin MICs in MHB supplemented to 20-25 microgram/ml of Ca2+ were 2-8 fold higher than those in MHB supplemented to 50 microgram/mL of Ca2+. CONCLUSION: Daptomycin is very active in vitro against methicillin-resistant staphylococci and vancomycin-resistant enterococci isolated in Korea, and it is important to test in vitro activity of daptomycin using MHB containing 50 microgram/mL of Ca2+.
Agar ; Ampicillin ; Calcium ; Daptomycin* ; Korea* ; Levofloxacin ; Linezolid ; Methicillin Resistance* ; Methicillin-Resistant Staphylococcus aureus ; Oxacillin ; Vancomycin

BACKGROUND: Daptomycin is a novel cyclic lipopeptide antibiotic that exhibits in vitro bactericidal activity against gram-positive pathogens including methicillin-resistant staphylococci and vancomycin-resistant enterococci. The aim of this study is to determine the in vitro activities of daptomycin against recent clinical isolates of methicillin-resistant staphylococci and vancomycin-resistant enterococci in Korea. MATERIALS AND METHODS: A total of 117 clinical strains of methicillin-resistant staphylococci and vancomycin-resistant enterococci were isolated at a tertiary-care hospital in Korea in 2004. Susceptibility to daptomycin was tested by the CLSI broth microdilution method using Mueller-Hinton broth (MHB) which was adjusted to contain a final concentration of 50 microgram/mL of ionized calcium (Ca2+). Susceptibilities to ampicillin, oxacillin, levofloxacin, vancomycin, and linezolid were tested by the CLSI agar dilution method. RESULTS: All isolates of methicillin-resistant S. aureus and coagulase-negative staphylococci were inhibited by 1 microgram/mL of daptomycin, and MIC90s were 1 microgram/mL, which were similar to those of vancomycin and linezolid. MIC90s of daptomycin for vancomycin-resistant E. faecalis and E. faecium were 0.5 microgram/mL and 2 microgram/mL, respectively, and all isolates were susceptible to daptomycin. MIC90s of linezolid and levofloxacin for vancomycin-resistant enterococci were 1-2 microgram/mL and 64 microgram/mL, respectively. Resistance rates of vancomycin-resistant E. faecalis and E. faecium to levofloxacin were 100% and 96%, respectively. Daptomycin MICs in MHB supplemented to 20-25 microgram/ml of Ca2+ were 2-8 fold higher than those in MHB supplemented to 50 microgram/mL of Ca2+. CONCLUSION: Daptomycin is very active in vitro against methicillin-resistant staphylococci and vancomycin-resistant enterococci isolated in Korea, and it is important to test in vitro activity of daptomycin using MHB containing 50 microgram/mL of Ca2+.
Agar ; Ampicillin ; Calcium ; Daptomycin* ; Korea* ; Levofloxacin ; Linezolid ; Methicillin Resistance* ; Methicillin-Resistant Staphylococcus aureus ; Oxacillin ; Vancomycin

PURPOSE: Group B streptococcal (GBS) meningitis is the leading cause of mortality and morbidity in neonates. There are limited current data regarding outcomes from GBS meningitis and factors that predict an adverse outcome. METHODS: Twenty-three cases of GBS meningitis that were proven by cerebrospinal fluid culture from 2000 to 2010 were retrospectively reviewed. RESULTS: All GBS meningitis cases occurred in young infants less than 3 months and were late-onset (> or =7 days). Four infants (17.4%) died, and three (13.0%) were neurologically impaired at hospital discharge. Compared to the 16 infants with normal neurologic examinations, the 7 infants who died or had adverse outcomes at hospital discharge were more likely to present with seizures within hours of admission, have coma, require pressor support or ventilator support, have an initial peripheral blood leukocyte count less than 4,000/mm3 or neutrophil count less than 1,000/mm3, and have ampicillin resistance on culture. CONCLUSION: Despite advances in intensive care, 30.4% of infants with GBS meningitis die or have neurologic impairment at hospital discharge. Poor outcome can be predicted in cases that have seizures, coma, peripheral leukopenia, or require ventilator or pressor support on initial presentation. These cases show a tendency toward resistance to ampicillin, so vancomycin can be tried initially.
Ampicillin ; Ampicillin Resistance ; Coma ; Humans ; Infant ; Infant, Newborn ; Critical Care ; Leukocyte Count ; Leukopenia ; Meningitis ; Neurologic Examination ; Neutrophils ; Prognosis ; Retrospective Studies ; Seizures ; Streptococcus agalactiae ; Vancomycin ; Ventilators, Mechanical

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*

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

PURPOSE: The purpose of this study is to investigate the clinical manifestations and antibiotic resistance of salmonellosis in children. METHODS: We reviewed medical records and investigated the clinical characteristics of culture-proven childhood salmonellosis from January 2000 through December 2011 at the CHA Bundang Medical center. RESULTS: We assessed 53 patients. The median age was 3-years-old (minimum 12 days, maximum 18-years-old) and the number of male patients was 33 (62.3%). It occurred most frequently in the summer (39%) and in 2001 (11 cases) however there was no case in 2009 and 2010. Salmonella typhi was isolated in 3 cases with septicemia. Antibiotic resistance to ampicillin was most frequently presented (30.2%) and 63.6% in serogroup B. No antibiotics resistance strains were cultured in patients with positive Salmonella typhi. Admitted patients from 2000 to 2011 were divided into 2 groups; group 1 from 2000 to 2005 and group 2 from 2006 to 2011. 40 cases belonged to group 1 and 13 cases were in the group 2. Group 2 showed more resistance to ampicillin than group 1 but without any statistical significance(25% vs. 38.5%, P=0.349). In group 1, the most common serotype was group D and in group 2, the most common serotype were group C and D. CONCLUSION: Salmonellosis in children was frequently occurred from 2000 to 2003 but decreased after 2004. There was no difference in clinical manifestations, serotypes and antibiotic resistances between the years.
Ampicillin ; Anti-Bacterial Agents ; Child ; Drug Resistance, Microbial ; Humans ; Male ; Medical Records ; Salmonella Infections ; Salmonella typhi ; Sepsis

The emergence and spread of antimicrobial resistance among the pathogenic and commensal Enterobacteriaceae are of great concern worldwide. We characterized the antimicrobial resistance and integrons found in commensal Escherichia coli from healthy humans in the community. Class 1 integrase (intl1) and class 2 integrase (intl2) genes were identified in 22 (13.3%) and 2 (1.2%) of 165 E. coli isolates, respectively. dfrA17-aadA5 and dfrA1-aadA2 were the most common class 1 integrons. The prevalence of each type of class 1 integron among commensal E. coli isolates during 2001~2003 was similar to that of clinical E. coli isolates from hospital-acquired infections during 1994~1999. The resistant rates of commensal E. coli isolates carrying intl1 to ampicillin, streptomycin, gentamicin, sulfamethoxazole, trimethoprim, chloramphenicol, and tetracycline were significantly higher than those of intl1-negative E. coli isolates (p<0.05). Integrons were directly associated with multidrug resistance in commensal E. coli isolates. It is hypothesized that multidrug-resistant Enterobacteriaceae from hospital-acquired infections are a potential reservoir for integrons associated with resistance genes found in commensal E. coli isolates in the community
Ampicillin ; Chloramphenicol ; Drug Resistance, Multiple ; Enterobacteriaceae ; Escherichia coli* ; Escherichia* ; Gentamicins ; Humans* ; Integrases ; Integrons* ; Prevalence ; Streptomycin ; Sulfamethoxazole ; Tetracycline ; Trimethoprim