Salmonella enterica serovar Typhimurium is one of the most important bacterial pathogens causing diarrhea. The resistance of S. typhimurium to antimicrobial agents, which has recently been isolated from patients, is causing serious problems. We investigated the effects of salicylic acid (Sal) and acetyl salicylate (AcSal) on the susceptibility of S. typhimurium to cephalosporin antibiotics, which are known to increase resistance to cephalosporin and quinolone antibiotics. The MIC of cephalosporin antibiotics was higher than that of the media without Sal. The rate of accumulation of ethidium bromide (EtBr) in the bacteria by the outer membrane protein (Omp) was not different from that of the bacteria cultured in the medium containing Sal. However, Carbonyl cyanide-m-chlorophenylhydrazone (CCCP), an inhibitor of bacterial efflux pumps, significantly reduced the rate of accumulation of EtBr in bacteria cultured on Sal containing medium. In the medium containing CCCP, the MIC of the antimicrobial agent tended to decrease as compared with the control. In addition, the MIC of the bacteria treated with CCCP and Sal was higher than that of the antimicrobial agent against the CCCP treated experimental bacteria. These results suggest that Sal decreases the expression of OmpF in the Omp of S. typhimurium and reduces the permeability of cephalosporin antibiotics to bacteria, which may induce tolerance to cephalosporin antibiotics.
Anti-Bacterial Agents ; Anti-Infective Agents ; Bacteria ; Carbonyl Cyanide m-Chlorophenyl Hydrazone ; Cephalosporin Resistance ; Cephalosporins ; Diarrhea ; Ethidium ; Humans ; Membrane Proteins ; Permeability ; Salicylic Acid ; Salmonella enterica ; Salmonella typhimurium ; Salmonella ; Serogroup

BACKGROUND/AIMS: To enable appropriate antimicrobial treatment for community-onset infections in emergency departments (EDs), data are needed on the resistance profiles of Escherichia coli and Klebsiella pneumoniae, which are the main pathogens of community-onset bacteremia. METHODS: Records were reviewed of 734 patients with E. coli and K. pneumoniae bacteremia who visited the Daegu Fatima Hospital ED, Daegu, Korea between 2003 and 2009. We investigated the demographic data, clinical findings, and antimicrobial susceptibility patterns of the organisms. RESULTS: Of 1,208 cases of community-onset bacteremia, 62.8% were caused by E. coli or K. pneumoniae in an ED of a secondary care hospital. Five hundred and forty-eight cases of E. coli (75%) and 183 cases of K. pneumoniae (25%) were analyzed. Urinary tract infection (43.1%) was most common, followed by intra-abdominal infection (39%) and pneumonia (7.2%). Trimethoprim/sulfamethoxazole, fluoroquinolone, third-generation cephalosporin (3GC) and amikacin resistance rates among E. coli and K. pneumoniae were 22.8%, 19.6%, 6.2%, and 1.3%, respectively. In 2009, the rate of 3GC resistance (10.6%) was significantly higher, compared to the annual averages of 2003 to 2008 (6.1%; p = 0.03). Previous exposure to antibiotics was an independent risk factor for 3GC resistance in multivariate logistic regression analysis. CONCLUSIONS: The rate of 3GC resistance increased in community-onset infections, and previous exposure to antibiotics was an independent risk factor. Despite the increased 3GC resistance in community-onset infections, an amikacin combination therapy could provide an option for treatment of bacteremic patients with previous antibiotic exposure in an ED.
Aged ; Aged, 80 and over ; Bacteremia/epidemiology/*microbiology ; *Cephalosporin Resistance ; Community-Acquired Infections/microbiology ; Emergency Service, Hospital/statistics & numerical data ; Escherichia coli/*physiology ; Female ; Humans ; Klebsiella pneumoniae/*physiology ; Male ; Middle Aged ; Republic of Korea/epidemiology ; Retrospective Studies ; Secondary Care Centers/statistics & numerical data

No abstract available.
Bacteremia/*microbiology ; *Cephalosporin Resistance ; Escherichia coli/*physiology ; Female ; Humans ; Klebsiella pneumoniae/*physiology ; Male

Although extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-EC) has emerged as a significant community-acquired pathogen, there is little epidemiological information regarding community-onset bacteremia due to ESBL-EC. A retrospective observational study from 2006 through 2011 was performed to evaluate the epidemiology of community-onset bacteremia caused by ESBL-EC. In a six-year period, the proportion of ESBL-EC responsible for causing community-onset bacteremia had increased significantly, from 3.6% in 2006 to 14.3%, in 2011. Of the 97 clinically evaluable cases with ESBL-EC bacteremia, 32 (33.0%) were further classified as healthcare-associated infections. The most common site of infection was urinary tract infection (n=35, 36.1%), followed by biliary tract infections (n=29, 29.9%). Of the 103 ESBL-EC isolates, 43 (41.7%) produced CTX-M-14 and 36 (35.0%) produced CTX-M-15. In the multilocus sequence typing (MLST) analysis of 76 isolates with CTX-M-14 or -15 type ESBLs, the most prevalent sequence type (ST) was ST131 (n=15, 19.7%), followed by ST405 (n=12, 15.8%) and ST648 (n=8, 10.5%). No significant differences in clinical features were found in the ST131 group versus the other group. These findings suggest that epidemic ESBL-EC clones such as CTX-M-14 or -15 type ESBLs and ST131 have disseminated in community-onset infections, even in bloodstream infections, which are the most serious type of infection.
Aging ; Bacteremia/drug therapy/*epidemiology ; Biliary Tract Diseases/epidemiology/microbiology ; Cephalosporin Resistance/genetics ; Cephalosporins/therapeutic use ; Community-Acquired Infections/*epidemiology/microbiology ; Escherichia coli/isolation & purification/metabolism ; Escherichia coli Infections/drug therapy/*epidemiology ; Female ; Humans ; Male ; Microbial Sensitivity Tests ; Molecular Epidemiology ; Multilocus Sequence Typing ; Prevalence ; Retrospective Studies ; Urinary Tract Infections/epidemiology/microbiology ; beta-Lactamases/*metabolism

BACKGROUND: Although healthcare-associated (HCA) Klebsiella pneumoniae bacteremia constitutes a significant proportion of community-onset infection cases, its clinical and microbiologic characteristics have yet to be described in detail. In this study, we sought to delineate the clinical differences between community-associated (CA) and HCA K. pneumoniae bacteremia. MATERIALS AND METHODS: A total of 240 patients infected by community-onset K. pneumoniae bacteremia were included in this study, and the data from the patients with HCA K. pneumoniae bacteremia were compared to those with the CA bacteremia. Isolates were microbiologically characterized and serotyped using a PCR method. RESULTS: Of the total 240 patients infected with community-onset K. pneumoniae bacteremia, 140 (58.3%) were defined as HCA infection cases, and the remaining 100 patients were classified as CA infections. Multivariate analysis showed that use of percutaneous tubes, occurrence of a recent surgical operation, cases of pneumonia, neutropenia and solid tumor, and prior receipt of antibiotics were all significant factors associated with HCA bacteremia infection (all P<0.05). In terms of microbiologic characteristics, ciprofloxacin resistance (12.9% [18/140] vs. 4.0% [4/100], P=0.02) and extended-spectrum beta-lactamase production (12.1% [17/140] vs. 4.0% [4/100], P=0.03) were more common in HCA bacteremia than CA bacteremia, respectively. The K1 and K2 serotypes, which are considered virulent community strains, were observed to exist more frequently in CA bacteremia than in HCA bacteremia (34% [34/100] vs. 21.4% [30/140], P=0.03). The overall 30-day mortality of the study population was 17.5% (37/211), and there was a trend toward greater mortality in the HCA group than in the CA group (21.4% [27/126] vs. 11.8% [10/85]; P=0.07). CONCLUSIONS: Patients infected with HCA bacteremia accounted for a substantial proportion of all patients with community-onset K. pneumoniae bacteremia, and showed significantly different clinical and microbiological characteristics than those infected with CA bacteremia. HCA K. pneumoniae bacteremia represented a distinct subset of community-onset bacteremia characterized by antibiotic resistant pathogens, a finding which physicians should consider in providing optimal treatment of these cases.
Anti-Bacterial Agents ; Bacteremia ; beta-Lactamases ; Cephalosporin Resistance ; Ciprofloxacin ; Community-Acquired Infections ; Humans ; Klebsiella ; Klebsiella pneumoniae ; Multivariate Analysis ; Neutropenia ; Pneumonia ; Polymerase Chain Reaction

The third generation cephalosporin is widely used in treatment of spontaneous bacterial peritonitis (SBP). Resistance to the third generation cephalosporin was associated with poor outcome in patients with SBP. Thus it is necessary to know the changes in resistance rate. We planned to investigate retrospectively on resistance rate of the third generation cephalosporin of gram negative bacteria isolated in patients with SBP, who visited Seoul National University Hospital between 1998 and 2006. The Clinical and Laboratory Standards Institute guidelines were applied for antibiotic susceptibility test. A total of 269 consecutive episodes of clinically and microbiologically proven SBP was identified during the study period and 209 cases were caused by gram negative organisms. Among 209 isolates, 22 (10.5%) showed resistance to the third generation cephalosporin. The prevalence of resistance was decreasing during the study period (P=0.014).
Cephalosporin Resistance ; Gram-Negative Bacteria* ; Humans ; Liver Cirrhosis ; Peritonitis* ; Prevalence ; Retrospective Studies ; Seoul

The third generation cephalosporin is widely used in treatment of spontaneous bacterial peritonitis (SBP). Resistance to the third generation cephalosporin was associated with poor outcome in patients with SBP. Thus it is necessary to know the changes in resistance rate. We planned to investigate retrospectively on resistance rate of the third generation cephalosporin of gram negative bacteria isolated in patients with SBP, who visited Seoul National University Hospital between 1998 and 2006. The Clinical and Laboratory Standards Institute guidelines were applied for antibiotic susceptibility test. A total of 269 consecutive episodes of clinically and microbiologically proven SBP was identified during the study period and 209 cases were caused by gram negative organisms. Among 209 isolates, 22 (10.5%) showed resistance to the third generation cephalosporin. The prevalence of resistance was decreasing during the study period (P=0.014).
Cephalosporin Resistance ; Gram-Negative Bacteria* ; Humans ; Liver Cirrhosis ; Peritonitis* ; Prevalence ; Retrospective Studies ; Seoul

BACKGROUND: Necrotizing fasciitis is a life threatening severe soft tissue infection primarily involving the fascia and the subcutaneous tissue with thrombosis of the cutaneous microcirculation. The purpose of the study was to analyze the microbiological and clinical characteristics of necrotizing fasciitis in Korea and to suggest adequate antibiotic therapy. METHODS: We retrospectively reviewed medical records of three Soonchunhyang University Hospitals in Seoul, Bucheon and Cheonan. Patients admitted for skin graft or secondary treatment were excluded. Blood cultures were obtained at the time of admission and pus cultures were obtained at the time of first operative debridement. RESULTS: Twenty two patients (16 males, 6 females, 16~82 years old, median age: 59 years old) were enrolled for this study. Fourteen pateints underwent surgical treatment and 2 of them died of necrotizing fasciitis. Gram positive organisms were isolated in 13 cases and gram negative organisms were isolated in 11 cases. Third generation cephalosporin resistant gram negative organisms were isolated in 3 cases. CONCLUSIONS: This study suggest that characteristics of necrotizing fascitis in Korea were; high proportion of aged person, predominance of type 2 necrotizing fascitis and increasing tendency of third generation cephalosporin resistant gram negative bacterial infections. Consequently, initial choice of empirical antibiotics for necrotizing fasciitis should consider 3rd generation cephalosporin resistant gram negative organisms. Prompt surgical debridement and adequate antimicrobial therapy are mandatory for improved survival.
Anti-Bacterial Agents ; Cephalosporin Resistance ; Chungcheongnam-do ; Debridement ; Fascia ; Fasciitis, Necrotizing* ; Female ; Gram-Negative Bacterial Infections ; Gyeonggi-do ; Hospitals, University* ; Humans ; Korea* ; Male ; Medical Records ; Microcirculation ; Retrospective Studies ; Seoul ; Skin ; Soft Tissue Infections ; Subcutaneous Tissue ; Suppuration ; Thrombosis ; Transplants

BACKGROUND: The therapeutic option is limited for the infections caused by organisms producing plasmid- mediated AmpC beta-lactamases, increasingly identified worldwide. Two sporadic patients with bacteremia caused by K. pneumoniae possessing an unusual inducible beta-lactam resistant phenotype were found in a university hospital. RESULTS:We conducted antibiotic susceptibility test according to NCCLS guideline. Also, we characterized beta-lactamase by isoelectric focusing. RESULTS: DHA-1 gene conferred the resistant phenotype. The patients had experienced treatment failure when treated with extended-spectrum cephalosporin. For the isolates the cephalosporin resistance was induced by clavulanic acid (and cefoxitin). CONCLUSION: Theses results suggest that the extended-spectrum cephalosporins might not provide optimal therapeutic option for inducible DHA-1-producing K. pneumoniae infection, even when the pathogens are susceptible in vitro.
Bacteremia ; beta-Lactamases* ; Cephalosporin Resistance ; Cephalosporins ; Clavulanic Acid* ; Humans ; Isoelectric Focusing ; Klebsiella pneumoniae* ; Klebsiella* ; Phenotype ; Pneumonia ; Treatment Failure

BACKGROUND: The therapeutic option is limited for the infections caused by organisms producing plasmid- mediated AmpC beta-lactamases, increasingly identified worldwide. Two sporadic patients with bacteremia caused by K. pneumoniae possessing an unusual inducible beta-lactam resistant phenotype were found in a university hospital. RESULTS:We conducted antibiotic susceptibility test according to NCCLS guideline. Also, we characterized beta-lactamase by isoelectric focusing. RESULTS: DHA-1 gene conferred the resistant phenotype. The patients had experienced treatment failure when treated with extended-spectrum cephalosporin. For the isolates the cephalosporin resistance was induced by clavulanic acid (and cefoxitin). CONCLUSION: Theses results suggest that the extended-spectrum cephalosporins might not provide optimal therapeutic option for inducible DHA-1-producing K. pneumoniae infection, even when the pathogens are susceptible in vitro.
Bacteremia ; beta-Lactamases* ; Cephalosporin Resistance ; Cephalosporins ; Clavulanic Acid* ; Humans ; Isoelectric Focusing ; Klebsiella pneumoniae* ; Klebsiella* ; Phenotype ; Pneumonia ; Treatment Failure