Antibiotic resistance profile in intrahospital pediatric services at third level centers in Dominican Republic / Perfil de resistencia a antibióticos en servicios pediátricos intrahospitalarios en centros de tercer nivel en República Dominicana

Objectives: The Dominican Republic lacks reliable information on antimicrobial resistance (AMR), which would allow physicians to prescribe the best treatment for common infectious diseases. This study aimed to define the antimicrobial resistance profiles of the more common pathogens from pediatric services, where data is even more important due to the vulnerability of the population. Methods: We collected data from patients admitted in the pediatric unit of three third level hospitals in the city of Santiago de los Caballeros, Dominican Republic, showing positive bacterial cultures, during a period of two years. Results: Half of the Gram negative pathogens exhibited third generation cephalosporins (3GC) resistance, 17% were resistant to carbapenems. Serratia marcescens presented an exceptionally high proportion of resistance to 3GC (95.9%). Staphylococcus aureus showed elevated resistance to methicillin (58.4%) and even to clindamycin (35.8%). Conclusion: There are elevated levels of antimicrobial resistance among the Enterobacteriaceae family and the Staphylococcus genus isolated from the pediatric population. Necessary measures should be taken to tackle AMR in the country.

Objetivos: La República Dominicana carece de información confiable sobre las resistencias antimicrobianas en el país, lo que permitiría al personal médico prescribir los mejores tratamientos para infecciones comunes. El objetivo de este estudio es definir los perfiles de resistencia antimicrobiana de los patógenos más comunes en servicios pediátricos, donde esta información es esencial, debido a la vulnerabilidad de la población. Métodos: Se tomaron los datos de reportes microbiológicos con cultivo bacteriano positivo procedentes de pacientes admitidos en la unidad pediátrica de tres hospitales de tercer nivel en la ciudad de Santiago de los Caballeros, República Dominicana, durante un periodo de dos años. Resultados: La mitad de los patógenos Gram negativos mostraron resistencia a cefalosporinas de tercera generación (3GC), 17% eran resistentes a carbapenémicos. Serratia marcescens presentó una resistencia excepcionalmente elevada a 3GC (95.9%). Staphylococcus aureus mostró alta resistencia a meticilina (58.4%) e incluso a clindamicina (35.8%). Conclusión: Existen elevados niveles de resistencia antimicrobiana entre las enterobacterias y los estafilococos en la población pediátrica dominicana. Es necesario tomar medidas para abordar este problema en el país.

Antimicrobial Profile of Clinical Isolates in Intensive Car e Unit at a Tertiary Care Hospital

Introduction: Intensive Care Units (ICU’s) provides a suitable environment for the proliferation and persistence of multidrug organisms. The burden of nosocomial infections among critically ill patients is much higher in developing countries. Aims and Objectives: The present study was conducted to know the prevalence of bacterial pathogens from various ICU’s of a tertiary care hospital and to determine their resistance profile. Materials and methods: A retrospective study was done on 188 isolates collected over a period of 10 months from January 2018 to October 2018. The isolates were identified by the conventional biochemical method and antimicrobial susceptibility testing was performed by Kirby bauer disc diffusion method. Results: The most common gram negative isolate obtained in this study was Klebsiella spp. About 90/188 (47.87%), followed by Pseudomonas aeruginosa 22/188 (11.70%), Acinetobacter spp. 21/188 (11.17%), and E. coli 20/188 (10.64%). The predominant gram positive cocci isolated were Enterococcus spp. 9/188 (4.79%). All gram negative bacilli were sensitive to Imipenem. About 23.33% of Klebsiella isolates were resistant to Piperacillin tazobactam and 18.89% to Cefoperazone sulbactam. The most effective drugs against gram negative bacilli were Imipenem, Piperacillin tazobactam, and Cefoperazone sulbactam. Conclusion: This study showed the prevalence of multidrug resistant Klebsiella spp. from various ICU’s. These isolates were resistant to third generation cephalosporins, quinolones, and aminoglycosides and were sensitive to carbapenems. Among the non-fermenting gram negative bacilli, the resistant rates were higher for Acinetobacter isolates compared to Pseudomonas aeruginosa.

Predictive factors for third-generation cephalosporin-resistant spontaneous bacterial peritonitis / 临床肝胆病杂志

ObjectiveTo investigate the predictive factors for third-generation cephalosporin-resistant spontaneous bacterial peritonitis (SBP). MethodsA retrospective analysis was performed for the clinical data of 206 patients with liver cirrhosis who were hospitalized in the Ninth Hospital of Nanchang from January 2010 to December 2018, and all patients had SBP with positive bacteria based on ascites culture. According to drug susceptibility results, the patients were divided into third-generation cephalosporin-resistant SBP group (101 patients with third-generation cephalosporin-resistant pathogenic bacteria in ascites) and control group (105 patients with pathogenic bacteria sensitive to third-generation cephalosporin). Electronic medical records were reviewed to collect related information. The t-test was used for comparison of normally distributed continuous data between groups, and the Mann-Whitney U test was used for comparison of data with skewed distribution between groups. The chi-square test or the Fisher’s exact test was used for comparison of categorical data between groups. A dichotomous logistic regression analysis was used for multivariate analysis, and the Forward: LR method was used for the screening of independent variables. ResultsThere was a significant difference in the composition of pathogenic bacteria between the two groups (P＜0.001). The univariate analysis showed that a history of broad-spectrum antibiotic exposure in the past three months (χ2=12.351, P＜0001), non-first-time onset of SBP (χ2=14.427, P＜0.001), blood creatinine (χ2=-2.537, P=0.011), and blood bicarbonate (χ2=-4.592, P＜0.001) were candidate predictive factors with statistical significance between the two groups, and further multivariate analysis showed that a history of broad-spectrum antibiotic exposure in the past three months (odds ratio ［OR］=2.376, 95% confidence interval ［CI］: 1.009-5.598, P=0.048), non-first-time onset of SBP (OR=2.841, 95%CI: 1.133-7.122, P=0.026), and blood bicarbonate (OR=0.892, 95%CI: 0.818-0.973, P=0.010) had an independent predictive value for third-generation cephalosporin-resistant SBP. ConclusionA history of broad-spectrum antibiotic exposure in the past three months, non-first-time onset of SBP, and a low level of blood bicarbonate are independent predictive factors for third-generation cephalosporin-resistant SBP, and third-generation cephalosporins should be used with caution in SBP patients with these features.

Research progress on status and mechanism of low sensitivity or resistance of Neisseria gonorrhoeae to cephalosporin / 中华全科医师杂志

Cephalosporin is still the first-line drug chosen for the treatment of gonorrhea, although it is likely to develop resistance to Neisseria gonorrhoeae. Recently, the resistance or low sensitivity of cephalosporin to Neisseria gonorrhoeae have been reported at home and abroad. The studies of resistance mechanism to Neisseria gonorrhoeae are particularly important. The resistance mechanism is mainly lied in three aspects. The first is the changes in antibiotic target sites, for example, the changes in penicillin-binding proteins would affect the binding of antibiotics to Neisseria gonorrhoeae; the second is the changes in bacterial cell membrane porin which effects drugs influxing; the third is the changes in efflux system which enhances the bacterial efflux capacity. To study and explore the mechanism of Neisseria gonorrhoeae resistance is of great importance for the prevention and treatment of gonorrhea.

Salicylic Acid Reduces OmpF Expression, Rendering Salmonella enterica Serovar Typhimurium More Resistant to Cephalosporin Antibiotics / 전남의대학술지

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.

Detección molecular de belactamasas de espectro extendido (BLEE) en enterobacterias aisladas en Asunción / Molecular detection of extended spectrum beta-lactamase (esbl) in enterobacteria isolated in Asunción

Las betalactamasas de espectro extendido (BLEE), son enzimas responsables de la hidrólisis del anillo betalactámico de penicilinas y cefalosporinas, excepto carbapemenes, inhibiendo así su actividad terapéutica. Si bien es posible la detección fenotípica de este mecanismo de resistencia por métodos convencionales, sólo los métodos moleculares permiten la identificación del gen responsable de dicha resistencia. El objetivo de este estudio descriptivo retrospectivo fue identificar los genes blaCTX-M2, blaPER-2, blaSHV y blaTEM, en aislamientos de enterobacterias productoras de BLEE,; de muestras clínicas colectadas entre julio 2007 y abril 2008, provenientes de dos hospitales de referencia de Asunción, Paraguay. La detección molecular de los genes se realizó por reacción en cadena de la polimerasa empleando oligonucleótidos específicos. De los 232 aislados BLEE analizados, el 83% (n=192) portó al menos un gen bla, en el 17% (n=40) restante no fue detectado ninguno de los genes incluido en el estudio. Se observaron las siguientes frecuencias: 49% (94/192) blaCTX-M2, 45% (86/192) blaSHV, 40% (77/192) blaTEM y 7% (13/192) blaPER-2. En el 47% (90/192) se detectó más de un gen, siendo la combinación blaCTX-M2+blaTEM+blaSHV, la más frecuente observada en 32 aislados. El blaCTX-M2 como el gen más frecuente en este estudio; concuerda con lo reportado en nuestro país y en Argentina. Este es el primer reporte de la presencia de blaTEM y blaSHV en Paraguay. Es de gran importancia el estudio de otros genes codificantes de resistencia, considerando la emergencia de otras BLEE en la región como blaCTX-M15 con actividad predominantemente ceftazidimasa.

Extended spectrum beta-lactamases (ESBLs), are enzymes responsible for thehydrolysis of the beta-lactam ring and resistance to both cephalosporins and penicillins,except carbapenems, therefore inhibiting its therapeutics activity. Even though, detectionof the phenotypic resistance mechanism by conventional methods is possible, onlymolecular methods allow identification of the gene responsible for the resistance. Theobjective of this retrospective study was to identify the blaCTX-M2, blaPER-2, blaSHV, blaTEMgenes in ESBL-producing enterobacteriaceae isolates, recovered from clinical samples collected between July 2007 and April 2008, from two reference hospitals in Asunción,Paraguay. Molecular gene detection was performed by polymerase chain reaction usingspecifics oligonucleotides. Out of the tested 232 ESBL-producing isolates, 83% (n=192)carried at least one of the bla genes as follows; 49% (94/192) blaCTX-M2, 45% (86/192)blaSHV, 40% (77/192) blaTEM and 7% (13/192) blaPER-2. In the rest 17% (n=40) none of thegenes included in this study was detected; in 47% (90/192) more than one gene wasdetected, resulting blaCTX-M2 + blaTEM + blaSHV as the most frequent combination in 32isolates. The presence of blaCTX-M2, as the most frequent codifying genes of BLEE is inagreement with previous reports in Paraguay and Argentina. This is the first report of thepresence of blaTEM and blaSHV circulating in Paraguay. It is of much importance the study ofothers codifying resistance genes, taking into account the emergence of other BLEE in theregion, such as blaCTX-M15, predominantly with ceftazidimase activity.

Clinical and Molecular Epidemiology of Community-Onset Bacteremia Caused by Extended-Spectrum beta-Lactamase-Producing Escherichia coli over a 6-Year Period

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.

Clinical and Microbiological Characteristics of Healthcare-Associated Infections in Community-Onset Klebsiella pneumoniae Bacteremia / 감염과화학요법

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.

Cefepime versus extended spectrum β-lactamase-producing Enterobacteriaceae

The objective of this study was to evaluate the susceptibility to cefepime of a large group of ESBL- producing enterobacteria recently isolated in a Brazilian teaching hospital . The study included 280 strains of ESBL-producing enterobacteria, isolated between 2005 and 2008. The presence of the genes blaCTX-M, blaTEM and blaSHV was determined by PCR and confirmed by nucleotide sequencing. Susceptibility testing for cefepime was performed by disc-diffusion, agar dilution method and E-test®. Among the isolates, 34 (12.1 percent) presented a cefepime inhibition zone > 21 and MIC < 8 mg/L by agar dilution and E-strip methods. The use of cefepime for the treatment of infections caused by ESBL-producing bacteria has been controversial. Some studies of PD/PK show the probability of achieving the required PD parameters for cefepime, when the MICs were < 8 mg/L, whereas others have reported therapeutic failure with the same MIC. Additional data is essential to come to terms about the report and treatment with cefepime in ESBL-producing organisms especially when these microorganisms are isolated from sterile sites and from critically ill patients.

Epidemiology of Ciprofloxacin Resistance and Its Relationship to Extended-Spectrum beta-Lactamase Production in Proteus mirabilis Bacteremia

BACKGROUND/AIMS: We evaluated the clinical features of ciprofloxacin-resistant Proteus mirabilis bacteremia and risk factors for ciprofloxacin resistance. METHODS: From October 2000 to July 2009, 37 patients with clinically significant P. mirabilis bacteremia were identified and data from patients with ciprofloxacin-resistant and ciprofloxacin-susceptible P. mirabilis bacteremia were compared. RESULTS: The most common underlying diseases were neurologic disease (37.8%) and solid tumors (29.7%). The most common site of infection was the urinary tract (35.1%). Ten of the 37 patients (27.0%) were infected with ciprofloxacin-resistant isolates, and univariate analysis revealed a significant relationship between ciprofloxacin-resistant P. mirabilis bacteremia and neurologic disease, recent operation, L-tube insertion, percutaneous tube use, and extended-spectrum beta-lactamase (ESBL) production (all p < 0.05). ESBL was detected in six of 10 (60%) ciprofloxacin-resistant isolates, while only three of 27 (11%) ciprofloxacin-susceptible isolates produced ESBL (p = 0.005). In a logistic regression analysis, ESBL production remained a significant factor associated with ciprofloxacin resistance, after adjusting for other variables. CONCLUSIONS: These data indicate a close association between ciprofloxacin resistance and ESBL-production in P. mirabilis bacteremia. This association is particularly troublesome because the therapeutic options for serious infections caused by ESBL-producing P. mirabilis are severely restricted.

Prevalence and Characterization of Plasmid-Medicated Quinolone Resistance Genes among Clinical Isolates of Extended-Spectrum Cephalosporin Resistant Enterobacter cloacae / 감염과화학요법

BACKGROUND: Extended-spectrum cephalosporins (ESCs)-resistant Enterobacter cloacae is one of the pathogens of nosocomial infection the incidence of which is on the rise. Moreover, plasmid-mediated quinolone resistance genes (PMQR genes) that reduce quinolone sensitivity have been shown to be widely distributed among clinical isolates of Enterobacteriaceae. This study was carried out to observe the distribution of PMQR genes in clinical isolates of E. cloacae resistant to ESCs. MATERIALS AND METHODS: Fourty-three ESCs-resistant E. cloacae strains from the blood collected during the span of 7 years, from 1994 to 2001, at Seoul National University Children's Hospital (SNUCH) were included in this study. Isoelectric focusing and enzyme specific PCR were performed to characterize beta-lactamase. The presence of qnrA, qnrB, qnrC, qnrS, qepA, and aac(6')-Ib-cr was determined by PCR, restriction enzyme analyses of PCR products, and DNA sequencing. Minimal inhibitory concentration (MIC) of several quinolones was measured by agar dilution method. RESULTS: The PMQR genes were detected in 9 (21%) of 43 ESCs-resistant E. cloacae isolates. Among them, five isolates were positive for qnrB2, and each two isolates harbored qnrB4 or qnrB5, respectively. qnrA, qnrC, qnrS or qepA was not identified. aac(6')-Ib was detected in 27 isolates, but aac(6')-Ib-cr was not found. Among the 9 qnrB-positive isolates, 5 produced SHV-12, 3 were derepressed mutants, and 1 produced pI 7.5 beta-lactamase. MIC ranges and percent resistances of nalidixic acid, ofloxacin, levofloxacin, and moxifloxacin for the PMQR genes-positive isolates were higher than PMQR genes-negative isolates. CONCLUSION: In this study, ESCs-resistant E. cloacae showed a high prevalence of PMQR genes, and qnrB was the only PMQR gene identified.

Prevalence and Characterization of Plasmid-Medicated Quinolone Resistance Genes among Clinical Isolates of Extended-Spectrum Cephalosporin Resistant Enterobacter cloacae / 감염과화학요법

BACKGROUND: Extended-spectrum cephalosporins (ESCs)-resistant Enterobacter cloacae is one of the pathogens of nosocomial infection the incidence of which is on the rise. Moreover, plasmid-mediated quinolone resistance genes (PMQR genes) that reduce quinolone sensitivity have been shown to be widely distributed among clinical isolates of Enterobacteriaceae. This study was carried out to observe the distribution of PMQR genes in clinical isolates of E. cloacae resistant to ESCs. MATERIALS AND METHODS: Fourty-three ESCs-resistant E. cloacae strains from the blood collected during the span of 7 years, from 1994 to 2001, at Seoul National University Children's Hospital (SNUCH) were included in this study. Isoelectric focusing and enzyme specific PCR were performed to characterize beta-lactamase. The presence of qnrA, qnrB, qnrC, qnrS, qepA, and aac(6')-Ib-cr was determined by PCR, restriction enzyme analyses of PCR products, and DNA sequencing. Minimal inhibitory concentration (MIC) of several quinolones was measured by agar dilution method. RESULTS: The PMQR genes were detected in 9 (21%) of 43 ESCs-resistant E. cloacae isolates. Among them, five isolates were positive for qnrB2, and each two isolates harbored qnrB4 or qnrB5, respectively. qnrA, qnrC, qnrS or qepA was not identified. aac(6')-Ib was detected in 27 isolates, but aac(6')-Ib-cr was not found. Among the 9 qnrB-positive isolates, 5 produced SHV-12, 3 were derepressed mutants, and 1 produced pI 7.5 beta-lactamase. MIC ranges and percent resistances of nalidixic acid, ofloxacin, levofloxacin, and moxifloxacin for the PMQR genes-positive isolates were higher than PMQR genes-negative isolates. CONCLUSION: In this study, ESCs-resistant E. cloacae showed a high prevalence of PMQR genes, and qnrB was the only PMQR gene identified.

Trend of Resistance to the Third Generation Cephalosporin of Gram Negative Bacteria in Patients with Spontaneous Bacterial Peritonitis / 감염과화학요법

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).

Trend of Resistance to the Third Generation Cephalosporin of Gram Negative Bacteria in Patients with Spontaneous Bacterial Peritonitis / 감염과화학요법

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).

Characteristics of necrotizing fasciitis in three university hospitals in Korea / 대한내과학회지

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.

Failure of Cephalosporin Treatment for Bloodstream Infection Caused by Apparently Susceptible Klebsiella pneumoniae which Produced DHA-1 beta-Lactamase Induced by Clavulanic Acid / 감염과화학요법

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.

Failure of Cephalosporin Treatment for Bloodstream Infection Caused by Apparently Susceptible Klebsiella pneumoniae which Produced DHA-1 beta-Lactamase Induced by Clavulanic Acid / 감염과화학요법

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.

Therapeutic Efficacy of Meropenem for Treatment of Experimental Penicillin-Resistant Pneumococcal Meningitis

With the widespread emergence of antimicrobial resistance, combination regimens of ceftriaxone and vancomycin (C+V) or ceftriaxone and rifampin (C+R) are recommended for empirical treatment of pneumococcal meningitis. To evaluate the therapeutic efficacy of meropenem (M), we compared various treatment regimens in arabbit model of meningitis caused by penicillin-resistant Streptococcus pneumoniae (PRSP). Therapeutic efficacy was also evaluated by the final bacterial concentration in the cerebrospinal fluid (CSF) at 24 hr. Each group consisted of six rabbits. C+V cleared the CSF at 10 hr, but regrowth was noted in 3 rabbits at 24 hr. Meropenem monotherapy resulted in sterilization at 10 hr, but regrowth was observed in all 6 rabbits at 24 hr. M+V also resulted in sterilization at 10 hr, but regrowth was observed in 2 rabbits at 24 hr. M+V was superior to the meropenem monotherapy at 24 hr (reduction of 4.8 vs. 1.8 log10 cfu/mL, respectively; p=0.003). The therapeutic efficacy of M+V was comparable to that of C+V (reduction of 4.8 vs. 4.0 log10 cfu/mL, respectively; p=0.054). The meropenem monotherapy may not be a suitable choice for PRSP meningitis, while combination of meropenem and vancomycin could be a possible alternative in the treatment of PRSP meningitis.