Multicenter Study on the Association of Positive Helicobacter pylori Stool Antigen to Anemia in Children / 대한임상미생물학회지

BACKGROUND: Helicobacter pylori infection in children causes gastrointestinal symptoms and iron deficiency anemia. This study aimed to investigate trends in H. pylori stool antigen (HpSA) positivity in children and the relationship between HpSA test results and anemia. METHODS: We analyzed the results of 2,762 HpSA tests and the correlation of hemoglobin and ferritin with HpSA in patients aged 0–18 years from 2008 to 2014 at a tertiary care center. Additionally, we prospectively evaluated HpSA test results and correlation with hemoglobin in 352 specimens obtained from five centers. RESULTS: From 2008-2014, the mean positive rate of the HpSA test was 5.8%, with a high of 9.1% in 2012 and a low of 2.3% in 2013. The positive rate correlated with age: 2.9% in 0–6-year-olds, 5.8% in 7–12-year-olds, and 10.6% in 13–18-year-olds (P < 0.0001). There was no difference in HpSA positivity in patients with (7.0%) and without (5.7%) anemia. Ferritin was significantly lower in patients with positive HpSA results than in those with negative results (P=0.0001). In a multicenter study, the positive rate of HpSA was 16.8%. CONCLUSION: The rate of HpSA positivity was 5.8% in pediatric patients at a single center from 2008–2014, and this rate increased with age. Helicobacter pylori infection may be associated with iron deficiency, as ferritin level was significantly lower in HpSA-positive patients than HpSA-negative patients.

Rapid Identification of Thrombocytopenia-Associated Multiple Organ Failure Using Red Blood Cell Parameters and a Volume/Hemoglobin Concentration Cytogram

Thrombocytopenia-associated multiple organ failure (TAMOF) has a high mortality rate when not treated, and early detection of TAMOF is very important diagnostically and therapeutically. We describe herein our experience of early detection of TAMOF, using an automated hematology analyzer. From 498,390 inpatients, we selected 12 patients suspected of having peripheral schistocytosis, based on the results of red blood cell (RBC) parameters and a volume/hemoglobin concentration (V/HC) cytogram. We promptly evaluated whether the individual patients had clinical manifestations and laboratory findings were consistent with TAMOF. Plasma exchanges were then performed for each patient. All 12 patients had TAMOF. The mean values of RBC parameters were significantly higher in all of the patients than with the reference range, however, 3 patients had % RBC fragments within the reference range. The mean value of ADAMTS-13 activity was slightly lower in patients compared with the reference range. Of the 12 patients, remission was obtained in 9 patients (75%) within 4 to 5 weeks using plasma exchanges. Three patients died. An increased percentage of microcytic hyperchromic cells with anisocytosis and anisochromia indicated the presence of schistocytes, making it an excellent screening marker for TAMOF. Identification of TAMOF with RBC parameters and a V/HC cytogram is a facile and rapid method along with an automated hematology analyzer already in use for routine complete blood cell counting test.

Increase of Ceftazidime- and Fluoroquinolone-Resistant Klebsiella pneumoniae and Imipenem-Resistant Acinetobacter spp. in Korea: Analysis of KONSAR Study Data from 2005 and 2007

PURPOSE: Antimicrobial resistance monitoring could be a useful source of information for treating and controlling nosocomial infections. We analyzed antimicrobial resistance data generated by Korean Hospitals and by a commercial laboratory in 2005 and 2007. MATERIALS AND METHODS: Susceptibility data for 2005 and 2007 were collected from 37 and 41 hospitals, respectively, and from one commercial laboratory. Intermediate susceptibility was not included in the calculation of resistance rates. RESULTS: Methicillin-resistant Staphylococcus aureus (MRSA) (64%), third-generation cephalosporin-resistant Klebsiella pneumoniae (29%), fluoroquinolone-resistant Escherichia coli (27%), Pseudomonas aeruginosa (33%), and Acinetobacter spp. (48%), and amikacin-resistant P. aeruginosa (19%) and Acinetobacter spp. (37%) were prevalent in hospitals in 2007. A gradual increase of vancomycin-resistant Enterococcus faecium and imipenem-resistant Acinetobacter spp. was observed. Higher incidences of third-generation cephalosporin-resistant E. coli and K. pneumoniae and imipenem-resistant P. aeruginosa were found in the commercial laboratory than in the hospitals. CONCLUSION: Methicillin-resistant S. aureus, third-generation cephalosporin-resistant K. pneumoniae, and fluoroquinolone-resistant E. coli, P. aeruginosa and Acinetobacter spp. remain prevalent in Korea, while the incidence of vancomycin-resistant E. faecium and imipenem-resistant Acinetobacter spp. has increased gradually. The higher prevalences of third-generation cephalosporin-resistant E. coli and K. pneumoniae, and imipenem-resistant P. aeruginosa in the commercial laboratory are a new concern.

Clinical Significance of von Willebrand Factor-Cleaving Protease (ADAMTS13) Deficiency in Patients with Sepsis-Induced Disseminated Intravascular Coagulation

BACKGROUND: Deficiency of von Willebrand factor-cleaving protease, a disintegrin-like and metalloprotease with thrombospondin type 1 motif 13 (ADAMTS13), is thought to be responsible for platelet aggregation and microthrombi formation, which in turn cause typical thrombotic microangiopathies. This deficiency is found in patients with thrombocytopenia-associated multiple organ failure such as thrombocytopenic purpura and disseminated intravascular coagulation (DIC). We evaluated the clinical significance of ADAMTS13 deficiency in patients with sepsis-induced DIC. MATERIALS AND METHODS: Nineteen patients with sepsis-induced DIC were enrolled. ADAMTS13 antigen levels were determined by Enzyme-Linked Immunosorbent Assay (ELISA) and activity levels were measured by fluorescence resonance energy transfer assay. Patients were categorized into two groups according to ADAMTS13 antigen level: less than 350 ng/mL or above. Clinical characteristics and survival were compared between the two groups. RESULTS: ADAMTS13 antigen level was less than 350 ng/mL in 7 patients and was above 350 ng/mL in 12 patients. There were no significant differences between the groups for age, sex, severity of illness, and other clinical characteristics. In patients with ADAMTS13 antigen level less than 350 ng/mL, in-hospital mortality was much higher (100% versus 25%, P=0.003) and 7-day survival was much shorter (P=0.023). CONCLUSION: Deficiency of ADAMTS13 could be thought to be associated with unfavorable outcome in patients with sepsis-induced DIC.

Clinical Significance of von Willebrand Factor-Cleaving Protease (ADAMTS13) Deficiency in Patients with Sepsis-Induced Disseminated Intravascular Coagulation

BACKGROUND: Deficiency of von Willebrand factor-cleaving protease, a disintegrin-like and metalloprotease with thrombospondin type 1 motif 13 (ADAMTS13), is thought to be responsible for platelet aggregation and microthrombi formation, which in turn cause typical thrombotic microangiopathies. This deficiency is found in patients with thrombocytopenia-associated multiple organ failure such as thrombocytopenic purpura and disseminated intravascular coagulation (DIC). We evaluated the clinical significance of ADAMTS13 deficiency in patients with sepsis-induced DIC. MATERIALS AND METHODS: Nineteen patients with sepsis-induced DIC were enrolled. ADAMTS13 antigen levels were determined by Enzyme-Linked Immunosorbent Assay (ELISA) and activity levels were measured by fluorescence resonance energy transfer assay. Patients were categorized into two groups according to ADAMTS13 antigen level: less than 350 ng/mL or above. Clinical characteristics and survival were compared between the two groups. RESULTS: ADAMTS13 antigen level was less than 350 ng/mL in 7 patients and was above 350 ng/mL in 12 patients. There were no significant differences between the groups for age, sex, severity of illness, and other clinical characteristics. In patients with ADAMTS13 antigen level less than 350 ng/mL, in-hospital mortality was much higher (100% versus 25%, P=0.003) and 7-day survival was much shorter (P=0.023). CONCLUSION: Deficiency of ADAMTS13 could be thought to be associated with unfavorable outcome in patients with sepsis-induced DIC.

Clarithromycin and Amoxicillin Susceptibility Testing of Helicobacter pylori by Disk Diffusion Method / 대한임상미생물학회지

BACKGROUND: CLSI provides a guideline only for a agar dilution method of testing clarithromycin susceptibility for Helicobacter pylori. This study was to evaluate a disk diffusion method for clarithromycin and amoxicillin. METHODS: One hundred and forty clinical isolates of H. pylori isolated from May 2005 to May 2007 were tested by the CLSI agar dilution method and a disk diffusion method using 2microgram (2CLR) and 15microgram (15CLR) clarithromycin disks and 2microgram (2AMX) and 10microgram (10AMX) amoxicillin disks. The interpretation criteria used for the disk diffusion method were established by linear regression and error rate-bounded method for disk diffusion zone of inhibition (DDZ) compared to MIC. RESULTS: Resistance and intermediate rates to clarithromycin were 21.4% and 1.4%, respectively. A number of isolates with MIC 0.5, 1, and 2 (microgram/mL) to amoxicillin were 7, 2, and 1, respectively. For 2CLR and 15CLR, the coefficients of determination (R2) between MIC and DDZ were 0.931 and 0.923 (P< 0.001), respectively, and the criteria for resistance/ susceptibility were 12/28 mm for 2CLR and 23/39 mm for 15CLR. For 2AMX and 10AMX, the R2 between MIC and DDZ were 0.478 and 0.421 (P< 0.001), respectively, and the criteria for resistance with breakpoint of 2microgram/mL were 21 mm for 2AMX and 32 mm for 10AMX. All isolates had DDZ<60 mm with 2CLR and 2AMX, but 61.4% and 75.7% of the isolates had DDZ<60 mm with 15CLR and 10AMX, respectively. CONCLUSION: Excellent correlation and agreement between MIC and DDZ were found for clarithromycin and amoxicillin. With 2microgram disks, the susceptibility breakpoints were 28 mm or less; thus, two disks could be tested in one plate.

Clinical Application of Fiblast(R) in Second Degree Burn

PURPOSE: Nowadays importance of growth factors in wound healing is being focused. Wound healing can be accelerated by various growth factors. Wound healing cascade consists of inflammatory, proliferative, and remodeling phases. Basic fibroblast growth factor (bFGF) helps proliferation of fibroblast and promotes angiogenesis and formation of granulation tissue through proliferative phase. We investigated the effect of recombinant basic fibroblast growth factor Fiblast(R) (Kaken Pharmaceutical, Japan) on second degree burns. METHODS: 57 patients from July 2009 to September 2009 with second degree burn were treated with bFGF. Average age, sex, cause of burn, depth of burn, location of wound, epithelization period and number of operation were studied. Recombinant bFGF was used with spraying. The bFGT was sprayed and wait for 30 seconds and then foam dressing was applied to wounds. The bFGF administration continued until the wound healed. RESULTS: The average healing time in the bFGF-treated group was 8.4+/-2.2 days (4~14 days). Among 57 patients, 19 patients had superficial second degree burn and the average healing time in the bFGF-treated group was 7.2+/-1.5 days (4~9 days), 30 patients had deep second degree burn and the average healing time in the bFGF-treated group was 11.2+/-1.7 days (9~14 days). 20 patients had deep second degree burn and were clinically considered to get operation during hospital course but eventually 8 of patients (40%) with deep second degree burn treated with bFGF underwent operation. CONCLUSION: The use of bFGF for second-degree burns decreased the wound healing time. Especially the use of bFGF decreased the rate of getting operation in deep second degree burn and increased the convenience of treatment.

Multicenter Study for the Frequency of 23S rRNA Point Mutations Associated with Clarithromycin Resistance in Helicobacter pylori in Korea / 대한임상미생물학회지

BACKGROUND: Clarithromycin resistance in Helicobacter pylori is a major cause of eradication therapy failure. The objective of this study was to determine the frequency and type of mutations in the 23S rRNA gene in Korea, which are associated with clarithromycin resistance. METHODS: From January 2008 to March 2008, 353 gastric biopsy specimens were collected from five university hospitals in Seoul and Kyunggido. H. pylori infection was defined as showing a positive result in at least one of the following three tests: a microaerophilic culture, a CLO test, and a Giemsa/silver stain. The frequencies of A2143G, A2142G, and the wild type of 23S rRNA and the presence of H. pylori were determined by Seeplex ClaR-H. pylori PCR (Seegene Inc., Seoul, Korea). Twenty-nine culture isolates were tested for susceptibility to clarithromycin by E-test (AB Biodisk, Solna, Sweden) or the CLSI (Clinical and Laboratory Standards Institute) disk diffusion test. RESULTS: From 176 H. pylori PCR-positive specimens, 23S rRNA gene mutations were detected in 38 isolates (21.6%), including 27 isolates of A2143G and 11 isolates of A2142G. Total mutation rates varied from 15.8% to 31.3% with the frequency of A2143G mutation alone varying from 8.5% to 25.0% among the five hospitals studied. There were 10 clarithromycin-resistant isolates found by susceptibility test and they were all positive for A2143G mutation. But, 3 of the 19 susceptible isolates were also positive for either A2143G or A2142G mutation. CONCLUSION: In Korea, the overall frequency of clarithromycin-resistant H. pylori was 21.6%; however, the type and frequency of the 23S rRNA mutations varied from hospital to hospital.

Epidemiology of Plasmid-Mediated AmpC beta-Lactamase Produced by Clinical Isolates of Klebsiella pneumoniae from Four University Hospitals in Korea / 병원감염관리

BACKGROUND: Plasmid-mediated AmpC beta-lactamases (PABLs) are cephalosporinases that confer resistance to a wide variety of beta-lactam drugs and that may thereby create serious therapeutic problems. The PABL-producing organisms are a major concern in nosocomial infections and should therefore be monitored in surveillance studies. METHODS: During the period of May to July 2004, 27 cefoxitin non-susceptible isolates of Klebsiella pneumoniae from four university hospitals (Seoul 2, Daejeon 1, and Choongju 1) were tested for antimicrobial susceptibility by the broth microdilution method. The cefoxitin non-susceptible isolates were further investigated by the double disk synergy test for extended-spectrum beta-lactamases, multiplex AmpC PCR, DNA sequencing, and pulsed-field gel electrophoresis (PFGE). RESULTS: PABL-producing K. pneumoniae were found in all the four hospitals. Eight (32%) of 25 PABL producers were also tested positive by double disk synergy tests. Susceptibilities of the PABL producers were as follows: ceftazidime, 4%; aztreonam, 36%; cefepime, 76%; and imipenem, 100%. Among the 25 K. pneumoniae isolates were 24 DHA-1 and 1 CMY-1 beta-lactamase producers. The PFGE patterns of the DHA-1-producing K. pneumoniae showed variable as well as identical patterns. CONCLUSION: PABL-producing K. pneumoniae is widespread among medical institutions in Korea. A DHA-1 type in K. pneumoniae was the predominant enzyme detected. Overall, despite many different PFGE patterns of the PABL producers, some outbreak and epidemic clones appear to be prevalent in some hospitals in Korea. For the prevention of the spread of PABL-producing K. pneumoniae, it should be identified accurately by the clinical laboratory.

Antimicrobial Resistance of Clinically Important Bacteria Isolated from 12 Hospitals in Korea in 2005 and 2006 / 대한임상미생물학회지

BACKGROUND: Emergence and spread of antimicrobial resistant bacteria make it difficult to treat infections. A rapid increase in antimicrobial-resistant bacteria has become a serious problem in many countries including Korea, and it is important to perform a nationwide study of antimicrobial resistance to obtain some basic data that will help solve these problems. The aim of this study was to determine the nationwide prevalence of resistance among frequently isolated bacterial pathogens in 2005 and 2006 in Korea. METHODS: We collected routine susceptibility data for medically important bacterial pathogens from 12 university and general hospital laboratories in Korea from April to September in 2005 and from January to June in 2006. Collected data was analyzed by patient group. RESULTS: The proportions of methicillin-resistant Staphylococcus aureus (MRSA) were 65% in 2005 and 72% in 2006, respectively. The resistance rates of Enterococcus faecium to vancomycin were 29% in 2005 and 24% in 2006. The non-susceptible rates of Streptococcus pneumoniae to penicillin were 68% in 2005 and 74% in 2006. The resistant rates of Escherichia coli and Klebsiella pneumoniae to the 3rd generation cephalosporin were 10~12% and 25~39%, respectively, in 2005 and 11~15% and 30~34% in 2006. In Citrobacter freundii, Enterobacter cloacae and Serratia marcescens, the resistance rates to 3rd generation cephalosporin were 23~31%, 32~34%, and 17~27%, respectively, in 2005 and 21~37%, 37~43%, and 13~31% in 2006. The resistance rates to imipenem and meropenem were 21% and 18%, respectively, in Pseudomonas aeruginosa and 18% and 25% in Acinetobacter baumannii in 2005; 29% and 20% in P. aeruginosa and 18% and 23% in A. baumannii in 2006. Cotrimoxazole and levofloxacin resistance rates of Stenotrophomonas maltophilia were 5% and 13%, respectively, in 2005 and 3% and 7% in 2006. There were no isolates resistant to 3rd generation cephalosporin and fluoroquinolone among non-typhoidal Salmonella in 2005. CONCLUSION: Antimicrobial resistance of medically important bacteria is still a serious problem in Korea. To manage the problem, a continuous nationwide surveillance and diversified investigation and effort have become more important.

Production of Antibody against Helicobacter pylori HP0231 / 대한진단검사의학회지

BACKGROUND: Stool antigen detection kits for diagnosis of infection of Helicobacter pylori have been widely used for their convenience, but are mostly imported. Since Helicobacter pylori strains show a distinctive genetic diversity, it is important to find a protein that is a common antigen among various strains and shows a strong immunogenicity for the development of a stool antigen detection kit. HP0231 protein strongly reacts with the sera of patients suffering from gastritis and peptic ulcer. Therefore, HP0231 is an excellent candidate as a target gene for this study. METHODS: Chromosomal DNA from H. pylori was isolated. HP0231 gene was amplified by PCR, cloned into pET28a(+) vector, and overexpressed using isopropyl-beta-D-thiogalactopyranoside in E. coli BL21 (DE3). HP0231 protein was purified by Ni-NTA affinity chromatography followed by electroelution after SDS-PAGE. Rabbits were immunized with the purified HP0231 protein for the production of antibodies. Rabbit anti-HP0231 antibody was partially purified and tested for the sensitivity and specificity using ELISA and Western Blot Analysis. RESULTS: The sequence of the cloned HP0231 gene was identical with the gene sequence from Genbank (AA216016). HP0231 gene was overexpressed and HP0231 protein was purified. Rabbit anti-HP0231 antibody produced after immunization with the purified HP0231 protein reacted with the purified HP0231 protein, cell extracts from cultured H. pylori, and stomach biopsy tissue from patients, but not with cell extracts from cultured E. coli used as a negative control. After 1 million fold dilution, rabbit anti-HP0231 antibody still reacted with 1 microgram of HP0231 protein. CONCLUSIONS: Rabbit anti-HP0231 antibody was produced to detect HP0231 protein of H. pylori and will be tested for the development of a stool antigen detection kit for H. pylori.

Mechanism of VanB Phenotype in Vancomycin-Resistant Enterococci carrying vanA gene / 대한진단검사의학회지

BACKGROUND: Recently, vancomycin-resistant enterococci (VRE) with the vanA genotype that are susceptible to teicoplanin have been described in Japan, Taiwan, and Korea. The investigators suggested three point mutations in the putative sensor domain of vanS or impairment of accessory proteins VanY and VanZ as an explanation for the VanB phenotype-vanA genotype VRE. In this study, we analyzed Tn1546-like elements to determine the molecular mechanisms responsible for the impaired glycopeptide resistance of clinical VRE isolates with VanB phenotype-vanA genotype from Korea. METHODS: From 2001 to 2004, 28 clinical isolates of Enterococcus faecium with VanB phenotypevanA genotype were collected from 8 different university hospitals in diverse geographic areas in Korea. For structural analysis of Tn1546-like elements, PCR amplifications for internal regions of Tn1546 were performed. The purified PCR products were directly sequenced with an ABI Prism 3100 DNA sequencer. RESULTS: The sequence data of the vanS regulatory gene revealed that none of the isolates had any point mutations in this gene. All 28 isolates had a complete or incomplete deletion of vanY gene. Of these, 13 strains represented a complete deletion of vanZ, and 2 strains showed the deletion of nucleotides near the end point of vanX. CONCLUSIONS: The mechanism of VanB phenotype-vanA genotype in VRE isolates from Korea is not point mutations of vanS but the rearrangements of vanX, vanY and vanZ.

Emergence of CTX-M-12, PER-1 and OXA-30 beta-Lactamase-Producing Klebsiella pneumoniae / 대한임상미생물학회지

BACKGROUND: The aim of this study was to determine a nation-wide prevalence of Ambler class A and D extended-spectrum-lactamases (ESBL) in Klebsiella pneumoniae isolates in Korea. METHODS: During the period of April to May 2005, 189 isolates of K.pneumoniae were collected from 11 Korean hospitals. Antimicrobial susceptibilities to ceftazidime and cefotaxime were tested by the disk diffusion method, and ESBL production was determined by double-disk synergy test. Determinants of ceftazidime or cefotaxime-resistance were transferred to Escherichia coli J53 (azide-resistant) by transconjugation. Genotypes of class A and D ESBL genes were determined by PCR amplification and sequencing. RESULTS: One hundred-sixty isolates of K.pneumoniae showed positive results in double-disk synergy test. The most prevalent ESBL was SHV-12 (n=148). Also detected were genes encoding ESBLs including TEM-52 (n=1), SHV-2a (n=2), CTX-M-3 (n=15), CTX-M-9 (n=6), CTX-M-12 (n=2), CTX-M-14 (n=9), CTX-M-15 (n=1), PER-1 (n=1), GES-5 (n=3), and OXA-30 (n=2) beta-lactamases. CONCLUSION: With the emergence of CTX-M-12, PER-1, and OXA-30 beta-lactamases, the ESBLs in K.pneumoniae isolates are becoming more diverse in Korea.

Emergence of CTX-M-12 and A Novel CTX-M Type Extended-Spectrum beta-Lactamaseproducing Klebsiella pneumoniae / 대한진단검사의학회지

BACKGROUND: The aims of this study were to survey the nation-wide susceptibilities of Klebsiella pneumoniae isolates against ceftazidime and cefotaxime and to determine the prevalence of class A extended-spectrum beta-lactamases (ESBLs). METHODS: During the period of February to July 2004, K. pneumoniae isolates intermediate or resistant to ceftazidime and/or cefotaxime were collected from 12 hospitals in Korea. Antimicrobial susceptibilities were determined by the disk diffusion and the agar dilution methods and ESBL-production was by double-disk synergy test. Ceftazidime or cefotaxime-resistance determinants of the ESBLproducers were transfered to Escherichia coli J53 by transconjugation. Searches for class A ESBL genes were performed by PCR amplication. RESULTS: Among 212 clinical K. pneumoniae isolates, 172 (81%) isolates showed positive results in double-disk synergy test; the most prevalent ESBL was SHV-12 (n=104). Genes encoding ESBLs including SHV-2 (n=6), SHV-2a (n=17), CTX-M-3 (n=18), CTX-M-9 (n=6), CTX-M-12 (n=1), CTX-M- 14 (n=27), CTX-M-15 (n=3), and a novel CTX-M-type beta-lactamases were also detected. CONCLUSIONS: It is concluded that diversity of ESBLs in K. pneumoniae isolates are increasing in Korea. CTX-M-12 has never been reported in Asia, and a novel CTX-M-type ESBL has emerged.

Mean Platelet Component Change according to Stage in Stroke Patients

OBJECTIVE: Decrease of platelet density by degranulation of activated platelet is well correlated with decrease of mean platelet component (MPC) value. We intended to investigate the change of MPC, mean platelet volume, and platelet count according to the stroke stage and difference between ischemic and hemorrhagic infarction. METHOD: Thirty eight patients (ischemic stroke 28 men, hemorrhagic stroke 10 men) and twenty age-matched healthy persons were included in this study. They were divided into acute stage group and subacute stage group. Each of them were sampled by venously and investigated about mean platelet component, mean platelet volume, and platelet counts. RESULTS: In ischemic stroke, there was statically (p <0.05) meaningful decrease of MPC value in acute stage (27.5+/-1.7) compared to control group (28.8+/-0.9). And MPC value in subacute stage showed meaningful increase (28.1+/-1.3) compared to acute stage but still remained in statically lower value compared to control value. In hemorrhagic stroke, there was no meaningful difference of MPC value in acute stage group (28.6+/-2.0) and subacute stage group (27.9+/-1.1) compared to control group. CONCLUSION: In ischemic stroke patients, MPC value in acute stage decreased meaningfully and this change might be useful as a landmark in predicting the activity of infarction.

Emergence of Plasmid-Mediated CMY-2 beta -Lactamase Produced by Clinical Isolates of Escherichia coli in Korea / 대한진단검사의학회지

BACKGROUND: Of the plasmid-mediated AmpC beta-lactamases (ABLs), CMY-2 is the most prevalent and is distributed in many countries. However, little is known about the emergence and characteristics of CMY-2 among Escherichia coli isolates in Korea. The aims of this study were to detect the emergence of the CMY-2 beta-lactamase in clinical isolates of E. coli from various regions in Korea. METHODS: Eighteen cefoxitin non-susceptible isolates of 1, 130 consecutive, nonrepeat isolates of E. coli at five university hospitals were tested for antimicrobial susceptibility by the broth microdilution method. The cefoxitin non-susceptible isolates were further investigated by AmpC disk tests, double disk synergy (DDS) tests, isoelectric focusing, CMY-2-specific PCR, DNA sequencing, and plasmid analysis. RESULTS: Seven (0.6%) isolates of plasmid-mediated ABL-producing E. coli were found at three of the five hospitals; all seven isolates produced CMY-2 beta-lactamase and one of the isolates was also tested positive by the DDS test. All isolates demonstrated different plasmid patterns by plasmid analysis. CONCLUSIONS: Our data indicate that CMY-2-producing E. coli has emerged and is prevalent in the medical institution in Korea. Therefore, constant surveillance is needed to prevent its further spread.

Prevalence of Ambler Class A Extended-Spectrum beta-Lactamase-Producing Escherichia coli and Klebsiella pneumoniae Isolates in Korea / 대한임상미생물학회지

BACKGROUND: The aim of this study is to determine the nationwide prevalence of Ambler class A extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae and to characterize genotypes of ESBLs. METHODS: During the period of February through July, 2003, E.coli and K.pneumoniae isolates were collected from 12 hospitals in Korea. Antimicrobial susceptibilities were tested by disk diffusion method, and ESBL-production was determined by the double-disk synergy test. MICs of beta-lactam antibiotics were tested by agar dilution method. Searches for bla TEM, bla SHV, bla CTX-M, bla PER-1, bla VEB, bla IBC, bla GES and bla TLA genes were performed by PCR amplification, and the genotypes of ESBLs were determined by direct nucleotide sequence analysis of amplified products. RESULTS: Resistance rates of E.coli (n=246) and K.pneumoniae (n=239) isolates to ceftazidime were 8.5% and 20.1%, respectively. Most prevalent Ambler class A ESBL genotypes in E.coli isolates were bla CTX-M-15 (n=4) and bla CTX-M-3 (n=3), and each of bla CTX-M-14, bla SHV-12, and bla TEM-52 gene was also found in one isolate. Most prevalent ESBL genotypes in K.pneumoniae were bla SHV-12 (n=30) and bla CTX-M-3 (n=13), and bla CTX-M-14 (n=5). bla SHV-2a (n=3), bla SHV-5 (n=2), bla TEM-52 (n=1), bla GES-3 (n=2) genes were also found. CONCLUSION: CTX-M-type ESBL-producing E.coli and K.pneumoniae isolates are spreading, and a GES-type ESBL has emerged in Korea.

The Prevalence of Antimicrobial Resistance in Helicobacter pylori Isolated in Daejeon / 대한임상미생물학회지

BACKGROUND: The most commonly used regimen for the eradication of Helicobacter pylori is combination of a proton pump inhibitor, clarithromycin, and two other antibiotics, metronidazole and amoxicillin. The increase in resistance to antibiotics seems to result in a decrease in eradication efficacy for H.pylori. We investigated the prevalence of antibiotic resistance in H.pylori isolated in Daejeon area. METHODS: A total of 31 clinical isolates of H.pylori were collected from the patients who underwent upper gastrointestinal endoscopy in Keonyang University Hospital during the period from March to July 2004. Antibiotic susceptibility tests for metronidazole, amoxicillin, and clarithromycin were performed by the E test (AB Biodisk, Sweden) on an egg yolk medium containing triphenyltetrazolium. The resistance break points for amoxicillin, metronidazole, and clarithromycin were defined as 0.5 microgram/mL, 8 microgram/mL, 1 microgram/mL, respectively. RESULTS: Resistance to amoxicillin, metronidazole, and clarithromycin was detected in 7.4% (2/27), 25.8% (8/31), 3.6% (1/28), respectively. CONCLUSION: The resistance to amoxicillin and clarithromycin was uncommon in Daejeon area.

Antimicrobial Resistance of Clinically Important Bacteria Isolated from 12 Hospitals in Korea in 2004 / 대한임상미생물학회지

BACKGROUND: A rapid increase in antimicrobial-resistant bacteria has become a serious problem in many countries including Korea, but the rate and pattern of antimicrobial resistance may vary significantly depending on countries and even on hospitals. The aim of this study was to determine the nationwide prevalence of resistance among frequently isolated bacterial pathogens in Korea. METHODS: Routine susceptibility data for medically important bacterial pathogens from 12 university hospital and general hospital laboratories in Korea were analysed by patient group. These pathogens had been isolated during the period from April to November in 2004. RESULTS: The proportion of methicillin-resistant Staphylococcus aureus (MRSA) was 67%. Van-comycin-resistance rate of Enterococcus faecalis was 1% and that of E.faecium was 20%. The resistance rates of Streptococcus pneumoniae to penicillin and Haemophilus influenzae to ampicillin were 70% and 54%, respectively. The resistant rates of Escherichia coli and Klebsiella pneumoniae were 7-10% and 26-31% to the 3rd generation cephalosporin, respectively. The resistance rates to 3rd generation cephalosporin were 22-30% in Citrobacter freundii, 35-44% in Enterobacter cloacae and 15-22 % in Serratia marcescens. Imipenem resistance rates of Pseudomonas aeruginosa and Acinetobacter baumannii were 26% and 17%. Cotrimoxazole and levofloxacin resistance rates of Stenotrophomonas maltophilia were 46% and 44%, respectively. CONCLUSION: Antimicrobial resistance rates of clinically important pathogens in Korea were still high and were generally higher among the bacteria isolated from the intensive care unit patients. Strict infection control and continuous nationwide surveillance program will be required to manage the antimicrobial resistance problem.

Antimicrobial Resistance of Clinically Important Bacteria Isolated from 12 Hospitals in Korea / 대한임상미생물학회지

BACKGROUND: A rapid increase in antimicrobial-resistant bacteria has become a serious problem in Korea. Moreover, the antibiotic resistance problem has worsened noticeably during the past several years. The aim of this study was to determine the prevalence of resistance among frequently isolated gram-positive and -negative bacteria in Korea. METHODS: Routine susceptibility data for medically important bacteria isolated during 6 months of 2003 were collected from 12 university and general hospital laboratories in Korea. RESULTS: The proportion of methicillin-resistant Staphylococcus aureus (MRSA) was 66%; however, vancomycin-resistant strains were not detected. The rates of vancomycin-resistant Enterococcus faecium and penicillin-nonsusceptible Streptococcus pneumoniae (PNSP) were 22% and 73%, respectively. The resistance rates to 3rd generation cephalosporins and monobactam were: Escherichia coli 8-12%, Klebsiella pneumoniae 18-22%, Citrobacter freundii 22-32%, Enterobacter cloacae 34-37%, and Serratia marcescens 12-21%, respectively. Imipenem resistance rates of Acinetobacter baumannii and Pseudomonas aeruginosa were 23% and 25%, respectively. CONCLUSIONS: Antimicrobial resistant strains were already prevalent among the clinically important isolates, especially, MRSA, PNSP, and extended-spectrum cephalosporin resistant gram-negative bacilli in Korea. The imipenem-resistant rates of A. baumannii and P. aeruginosa increased, respectively, from 13% and 20% in 2002 to 23% and 25% in 2003. The results of this study will provide a basis for proper treatment of bacterial infections and prevention of spread of resistant bacteria. A continuous nationwide surveillance of antimicrobial resistance is very important and should be performed.