Book Review: “The New Microbiology: From Microbiomes to CRISPR” / 대한임상미생물학회지

At the time when owing to COVID-19 pandemic, the public is more interested in infectious diseases and pathogens than in any other period, a book titled “The New Microbiology: From Microbiomes to CRISPR” by the renowned microbiologist Pascale Cossart was translated and published by our colleague. In this book, the author describes important discoveries and new conceptual advances in the field of microbiology over the past century. The author emphasizes that bacteria form a microbiome and lead a social life and explains the impact and importance of the microbiome on human health and ecosystem. Further, the discovery of ‘CRISPR,’ which led to the era of genome editing and gene therapy, has been described in details. This book will dramatically change our perspective regarding all living things, including bacteria, plants, animals, and even insects, as well as our eating habits and daily life, based on the new understanding of microorganisms. I recommend reading this book as I am sure that it will broaden the perspectives of both clinical microbiologists and health care workers.

Comparison of Nasopharyngeal Aspirates and Nasopharyngeal Flocked Swabs for Respiratory Virus Detection / 대한임상미생물학회지

BACKGROUND: Nasopharyngeal aspirate (NPA) is known as the best specimen for accurate diagnosis of viral respiratory infections in pediatric patients, but the procedure is very annoying. Recently introduced flocked swabs have been reported to be easy to obtain a good quality specimen and comfortable to patients. The purpose of this study was to compare the sensitivities between NPA and nasopharyngeal flocked swabs (NPFS) for detection of respiratory viruses in children. METHODS: For this study, 111 hospitalized children with acute respiratory tract infections were recruited. NPA and NPFS were performed in parallel from each patient. NPFS were always collected after NPA. Specimens were tested for six common respiratory viruses in triplicate using indirect immunofluorescence (IIF), viral cultures, and multiplex reverse transcription PCR (RT-PCR). RESULTS: The proportion of specimens inadequate for IIF was higher in NPA (23.4%) than NPFS (5.4%). According to the consensus positive, the positive rates of NPFS were higher than those of NPA when using IIF (45.7% and 30.6%, P=0.048) and culture (38.7% and 27.9%, P=0.004). However, the false-positive rates of NPFS were higher than those of NPA when using IIF (12.4% and 1.2%, P=0.004). The positive rates of NPFS and those of NPA were not different in multiplex RT-PCR (67.6% and 55.9%, P=0.055). CONCLUSION: The higher sensitivity of IIF for NPFS specimens and of culture for respiratory viruses and the similar sensitivities in multiplex PCR could make them an alternative to NPA samples, especially in physician clinics or emergency rooms.

Clinical Characteristics of Symptomatic Clostridium difficile Infection in Children: Conditions as Infection Risks and Whether Probiotics Is Effective / 대한소아소화기영양학회지

PURPOSE: This study investigated the clinical presentations of symptomatic Clostridium difficile infection (CDI) in children. METHODS: We reviewed the medical records of 43 children aged 3 days, and the most frequently prescribed antibiotic was amoxicillin-clavulanate (35.7%). Twenty-eight patients were diagnosed with CDI despite taking probiotic supplements, most commonly Lactobacillus acidophilus (53.6%). The most common symptom was diarrhea (72.1%) at the time CDI was diagnosed. C. difficile was eradicated in 11 patients (25.6%) after treatment with oral metronidazole for 10-14 days, and in the two patients (4.6%) who required two courses of oral metronidazole. Sixteen patients (37.2%) showed clinical improvement without any treatment. CONCLUSION: This study showed the various clinical characteristics of CDI in children and that preexisting clinical conditions favored the development of CDI. In addition, CDI was found to occur in a number of patients even after probiotic prophylaxis given in conjunction with antibiotic therapy.

Comparison of Supplemented Brucella Agar and Modified Clostridium difficile Agar for Antimicrobial Susceptibility Testing of Clostridium difficile

BACKGROUND: Antimicrobial susceptibility testing (AST) of Clostridium difficile is increasingly important because of the rise in resistant strains. The standard medium for the AST of C. difficile is supplemented Brucella agar (sBA), but we found that the growth of C. difficile on sBA was not optimal. Because active growth is critical for reliable AST, we developed a new, modified C. difficile (mCD) agar. C. difficile grew better on mCD agar than on sBA. METHODS: C. difficile isolates were collected from patients with healthcare-associated diarrhea. sBA medium was prepared according to the CLSI guidelines. Homemade mCD agar containing taurocholate, L-cysteine hydrochloride, and 7% horse blood was used. For 171 C. difficile isolates, we compared the agar dilution AST results from mCD agar with those from sBA. RESULTS: No significant differences were observed in the 50% minimal inhibitory concentration (MIC50) and 90% minimal inhibitory concentration (MIC90) of clindamycin (CLI), metronidazole (MTZ), moxifloxacin (MXF), piperacillin-tazobactam (PTZ), and rifaximin (RIX), but the values for vancomycin (VAN) were two-fold higher on mCD agar than on sBA. The MICs of CLI, MXF, and RIX were in 100% agreement within two-fold dilutions, but for MTZ, VAN, and PTZ, 13.7%, 0.6%, and 3.1% of the isolates, respectively, were outside the acceptable range. CONCLUSIONS: The MIC ranges, MIC50 and MIC90, were acceptable when AST was performed on mCD agar. Thus, mCD agar could be used as a substitute medium for the AST of C. difficile.

Susceptibility of Escherichia coli from Community-Acquired Urinary Tract Infection to Fosfomycin, Nitrofurantoin, and Temocillin in Korea

With increase of multi-drug resistant Escherichia coli in community-acquired urinary tract infections (CA-UTI), other treatment option with a therapeutic efficacy and a low antibiotic selective pressure is necessary. In this study, we evaluated in vitro susceptibility of E. coli isolates from CA-UTI to fosfomycin (FM), nitrofurantoin (NI), temocillin (TMO) as well as trimethoprim-sulfamethoxazole (SMX), ciprofloxacin (CIP) and cefepime (FEP). The minimal inhibitory concentrations were determined by E-test or agar dilution method according to the Clinical and Laboratory Standards Institute guidelines, using 346 E. coli collected in 12 Korean hospitals from March 2010 to February 2011. FM, NI and TMO showed an excellent susceptibility profile; FM 100% (346/346), TMO 96.8% (335/346), and NI 99.4% (344/346). Conversely, resistance rates of CIP and SMX were 22% (76/346) and 29.2% (101/349), respectively. FEP still retained an activity of 98.5%. In Korea, NI and TMO in addition to FM are a good therapeutic option for uncomplicated CA-UTI, especially for lower UTI.

Susceptibility of Escherichia coli from Community-Acquired Urinary Tract Infection to Fosfomycin, Nitrofurantoin, and Temocillin in Korea

With increase of multi-drug resistant Escherichia coli in community-acquired urinary tract infections (CA-UTI), other treatment option with a therapeutic efficacy and a low antibiotic selective pressure is necessary. In this study, we evaluated in vitro susceptibility of E. coli isolates from CA-UTI to fosfomycin (FM), nitrofurantoin (NI), temocillin (TMO) as well as trimethoprim-sulfamethoxazole (SMX), ciprofloxacin (CIP) and cefepime (FEP). The minimal inhibitory concentrations were determined by E-test or agar dilution method according to the Clinical and Laboratory Standards Institute guidelines, using 346 E. coli collected in 12 Korean hospitals from March 2010 to February 2011. FM, NI and TMO showed an excellent susceptibility profile; FM 100% (346/346), TMO 96.8% (335/346), and NI 99.4% (344/346). Conversely, resistance rates of CIP and SMX were 22% (76/346) and 29.2% (101/349), respectively. FEP still retained an activity of 98.5%. In Korea, NI and TMO in addition to FM are a good therapeutic option for uncomplicated CA-UTI, especially for lower UTI.

Clinical and Microbiologic Characteristics of Clostridium difficile Infection Caused by Binary Toxin Producing Strain in Korea / 감염과화학요법

BACKGROUND: Binary toxin-producing Clostridium difficile infections (CDI) are known to be more severe and to cause higher case fatality rates than those by binary toxin-negative isolates. There has been few data of binary toxin-producing CDI in Korea. Objective of the study is to characterize clinical and microbiological trait of CDI cause by binary-toxin producing isolates in Korea. MATERIALS AND METHODS: From September 2008 through January 2010, clinical characteristics, medication history and treatment outcome of all the CDI patients were collected prospectively. Toxin characterization, PCR ribotyping and antibiotic susceptibility were performed with the stool isolates of C. difficile. RESULTS: During the period, CDI caused by 11binary toxin-producing isolates and 105 toxin A & toxin B-positive binary toxin-negative isolates were identified. Comparing the disease severity and clinical findings between two groups, leukocytosis and mucoid stool were more frequently observed in patients with binary toxin-positive isolates (OR: 5.2, 95% CI: 1.1 to 25.4, P = 0.043; OR: 7.6, 95% CI: 1.6 to 35.6, P = 0.010, respectively), but clinical outcome of 2 groups did not show any difference. For the risk factors for acquisition of binary toxin-positive isolates, previous use of glycopeptides was the significant risk factor (OR: 6.2, 95% CI: 1.4 to 28.6, P = 0.019), but use of probiotics worked as an inhibitory factor (OR: 0.1, 95% CI: 0.0 to 0.8; P = 0.026). PCR ribotypes of binary toxinproducing C. difficile showed variable patterns: ribotype 130, 4 isolates; 027, 3 isolates; 267 and 122, 1 each isolate and unidentified C1, 2 isolates. All 11 binary toxin-positive isolates were highly susceptible to clindamycin, moxifloxacin, metronidazole, vancomycin and piperacillin-tazobactam, however, 1 of 11 of the isolates was resistant to rifaximin. CONCLUSIONS: Binary toxin-producing C. difficile infection was not common in Korea and those isolates showed diverse PCR ribotypes with high susceptibility to antimicrobial agents. Glycopeptide use was a risk factor for CDI by those isolates.

Further Increases in Carbapenem-, Amikacin-, and Fluoroquinolone-Resistant Isolates of Acinetobacter spp. and P. aeruginosa in Korea: KONSAR Study 2009

PURPOSE: The increasing prevalence of antimicrobial resistant bacteria has become a serious worldwide problem. The aim of this study was to analyze antimicrobial resistance data generated in 2009 by hospitals and commercial laboratories participating in the Korean Nationwide Surveillance of Antimicrobial Resistance program. MATERIALS AND METHODS: Susceptibility data were collected from 24 hospitals and two commercial laboratories. In the analysis, resistance did not include intermediate susceptibility. Duplicate isolates were excluded from the analysis of hospital isolates, but not from the commercial laboratory isolates. RESULTS: Among the hospital isolates, methicillin-resistant Staphylococcus aureus, penicillin G-non-susceptible Streptococcus pneumoniae based on meningitis breakpoint, and ampicillin-resistant Enterococcus faecium remained highly prevalent. The proportion of vancomycin-resistant E. faecium gradually increased to 29%. Ceftazidime-resistant Escherichia coli and Klebsiella pneumoniae increased to 17% and 33%, respectively, and fluoroquinolone-resistant K. pneumoniae, Acinetobacter spp. and Pseudomonas aeruginosa increased to 33%, 67% and 39%, respectively. Amikacin-resistant Acinetobacter spp. increased to 48%. Imipenem-resistant Acinetobacter spp. and P. aeruginosa increased to 51% and 26%, respectively. Higher resistance rates were observed in intensive care unit (ICU) isolates than in non-ICU isolates among the isolates from hospitals. Resistance rates were higher in hospital isolates than in clinic isolates among the isolates from commercial laboratories. CONCLUSION: Among the hospital isolates, ceftazidime-resistant K. pneumoniae and fluoroquinolone-resistant K. pneumoniae, Acinetobacter spp., and P. aeruginosa further increased. The increase in imipenem resistance was slight in P. aeruginosa, but drastic in Acinetobacter spp. The problematic antimicrobial-organism combinations were much more prevalent among ICU isolates.

Occupational Infections of Health Care Personnel in Korea / 한양의대학술지

Healthcare personnel (HCP) face a wide range of occupational hazards, including needle-stick injuries, back injuries, latex allergy, violence, and stress. In particular, occupational exposures to infectious agents, such as human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV),or tuberculosis, are devastating to the victims. The World Health Organization (WHO) estimates the global burden of disease from occupational exposure to be 40% of hepatitis B and C virus infections and 2.5% of the HIV infections among HCP. Infectious disease cases for which compensation is given by the Korean Occupational Safety and Health Agency are increasing, and tuberculosis is the most common infectious disease compensated by KOSHA for HCP in Korea. While viral respiratory infections are common in health care settings, systematic surveillance has not been established yet in Korea. Infection control programs for HCP, such as engineering control in medical facilities, immunization, post exposure prophylaxis, and use of personal protective equipment need to be improved in Korea. This article describes the epidemiologic characteristics of occupational infectious diseases among HCP in Korea, especially focusing on needle-stick injuries and airborne infections. Also brief commentary is offered concerning effective measures for the control and prevention of occupational infectious disease transmission among HCP.

Evaluation of Automated Blood Culture System for Body Fluids Culture Other Than Blood / 대한임상미생물학회지

BACKGROUND: We investigated whether culture using an automated blood culture system enhances the recovery of bacteria and fungi from body fluids other than blood when compared to conventional solid media culture methods. METHODS: A total of 734 specimens [ascites (n=457), bile (n=5), CAPD (n=28), CSF (n=32), joint fluids (n=165), pericardial fluid (n=17), and pleural fluid (n=30)] were included in the study. Half of the volume of each specimen was inoculated directly into automated blood culture bottles (bioMeriux, Marcy-I'Etoile, France). The remaining volume was inoculated onto conventional solid media (sheep blood agar, chocolate agar, and phenylethyl alcohol agar) after centrifuging at 3,000 rpm for 10 min. RESULTS: Clinically significant microorganisms were isolated from 62 specimens (8.5%) by automated blood culture and 61 specimens (8.3%) by the conventional solid media culture (kappa index: 0.81, 95% confidence interval: 0.75~0.89). Contamination was observed in 11 (1.8%) of the automated blood culture specimens and 3 (0.4%) of the solid media culture specimens. The mean turnaround times of the automated blood cultures and the conventional solid media cultures were 3.7 and 2.8 days, respectively (P<0.0001). CONCLUSION: Compared with conventional culture methods, no improvement in the recovery of clinically significant microorganisms was noted with the use of the automated blood culture system for the culture of body fluids other than blood.

Epidemiology and Clinical Characteristics of Clostridium difficile Infection in a Korean Tertiary Hospital

In order to investigate the incidence, clinical and microbiologic characteristics of Clostridium difficile infection (CDI) in Korea, a prospective observational study was performed. From September 2008 through January 2010, all patients whose stool was tested for toxin assay A&B and/or C. difficile culture were studied for clinical characteristics. Toxin types of the isolates from stool were tested. The mean incidence of CDI per 100,000 patient-days was 71.6 by month (range, 52.5-114.0), and the ratio of CDI to antibiotic-associated diarrhea was 0.23. Among 200 CDI patients, 37.5% (75/200) was severe CDI based on severity score. Clinical outcome of 189 CDI was as followed; 25.9% (49/189) improved without treatment, 84.3% (118/140) achieved clinical cure and attributed mortality was 0.7% (1/140) with the treatment. Recurrence rate was 21.4% (30/140) and cure without recurrence was 66.4% (93/140). The most common type of toxin was toxin A-positive/toxin B-positive strain (77.5%), toxin A-negative/toxin B-positive strains or binary toxin-producing strains comprised 15.4% or 7.1%, respectively. In conclusion, the incidence of CDI in Korea is a little higher than other reports during the non-epidemic setting. We expect that the change of epidemiology and clinical severity in CDI can be evaluated based on these results.

Multicenter Study of Molecular Epidemiology and Antibiotic Resistance of Group A Streptococci in 2008-2009 in Korea / 대한임상미생물학회지

BACKGROUND: Group A Streptococcus (GAS) is responsible for a wide spectrum of human diseases. We investigated the distribution of emm types and antibiotic resistance rates of GAS from clinical specimens in several Korean medical centers. METHODS: A total of 192 strains of GAS from throat, blood, and other specimens collected in Seoul, Busan, Ulsan, Iksan, and Jeju were studied in 2008-2009. The emm genotypes were identified using PCR and sequencing. Antimicrobial susceptibility testing was performed by disk diffusion method. Phenotypes of macrolide resistance were evaluated, and macrolide resistance genes were determined by PCR. RESULTS: The emm89 (33.9%) was most frequently detected, followed by emm1 (12.5%), emm12 (8.3%), emm4 (7.8%), and emm75 (7.3%). The distribution of emm types did not show a close relation to the type of specimen and was different for each area. The resistance rates to erythromycin (ERY) and clindamycin (CLI) were 4.6% and 3.7%, respectively. Among the nine ERY-resistant strains, the rate of constitutive resistance was 88.9%, compared with 11.1% for the M phenotype. Five of the ERY-resistant strains were emm28. CONCLUSION: This multicenter study reveals heterogenous emm genotypes by geographic area. Rates of resistance to ERY and CLI were low, and most of the ERY-resistant strains showed a constitutive macrolide-lincosamide-streptogramin B (cMLSB) phenotype.

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.

Metallo-beta-Lactamase-Producing Pseudomonas spp. in Korea: High Prevalence of Isolates with VIM-2 Type and Emergence of Isolates with IMP-1 Type

PURPOSE: Two Korean nationwide studies showed that metallo-beta-lactamases (MBLs)-producing-Pseudomonas spp. are not rare. The aim of this study was to assess the trends of MBL-producing isolates among imipenem-resistant isolates of Pseudomonas spp. MATERIALS AND METHODS: Imipenem-resistant clinical isolates were collected from 23 hospitals and one commercial laboratory participating in the KONSAR program in 2005. Polymerase chain reaction (PCR) was used to detect MBL genes. RESULTS: Alleles of MBL genes were detected in 10.8% of 415 Pseudomonas aeruginosa and 66.7% of 12 P. putida isolates from 18 of 24 hospitals/laboratory. Among the 14 IMP-1-like and 39 VIM-2-like MBLs, emergence of IMP-6 was detected for the first time. CONCLUSION: Prevalence of MBL-producing P. aeruginosa has not significantly increased, but IMP-6 emerged in P. aeruginosa.

Clinical Characteristics and Changing Epidemiology of Clostridium difficile-Associated Disease (CDAD) / 대한소화기학회지

BACKGROUND/AIMS: The spectrum of Clostridium difficile-associated disease (CDAD) ranges from mild diarrhea to life-threatening colitis. Recent studies reported an increase in incidence and severity of CDAD and the presence of severe community-acquired CDAD (CA-CDAD). The aims of this study were to investigate the incidence of CA-CDAD and non-antibiotics-associated CDAD, and to compare the clinical characteristics between hospital-acquired (HA) and CA-CDAD. METHODS: The medical records of 86 patients who were diagnosed as CDAD in Hanyang University Guri Hospital between January 2005 and October 2007 were retrospectively reviewed. RESULTS: Of the 86 patients (mean age 64 years), 53 patients were women. The most frequently prescribed antibiotics were cephalosporins (67.4%), followed by aminoglycosides (38.4%) and quinolones (14%). Of the 86 patients, the average duration of treatment and recovery time of symptoms were 11.5 days and 4.6 days, respectively. Seven percent of patients experienced relapse treatment. The overall incidence rate of CA-CDAD and non-antibiotics-associated CDAD were 10.5% and 22.1%, respectively. CA-CDAD group had lower rate of antimicrobial exposure whilst showing higher rate of complications compared to HA-CDAD group. Three patients in the CA-CDAD progressed towards a severe complicated clinical course, including septic shock. CONCLUSIONS: The incidence rate of CA-CDAD and non-antibiotics-associated CDAD were 10.5% and 22.1%, respectively. CA-CDAD tends to have a higher complication rate compared to HA-CDAD. Community clinicians needs to maintain a high level of suspicion for CDAD, whilst coping with the ever evolving epidemiologic change.

Rapid Screening of Vancomycin Resistant Enterococci with Chromogenic Agar (ChromID VRE) / 병원감염관리

BACKGROUND: Rapid screening of vancomycin-resistant enterococci (VRE) is very important for controlling and preventing the spread of VRE in hospitals. We compared the performance characteristics of a chromogenic agar (ChromID VRE, bioMerieux, France: CA) to that of Enterococcosel agar (supplemented with 6 microgram/mL of vancomycin :EA) for direct detection of VRE from stool swabs. METHODS: Total 125 rectal swabs were collected from 57 patients in the intensive care units of an 850-bed university hospital over a period of 3 months. The samples were inoculated on EA, CA and into broth enrichment containing 6 microgram/mL of vancomycin (BE). BE was subcultured on CA after overnight incubation. RESULTS: Eighty two samples from 22 patients were positive for VRE by BE. At 24 h, the sensitivity/specificity of EA and CA were 89%/100% and 72%/100%, respectively. At 48 h, the sensitivity/specificity of EA and CA were 94%/89% and 89%/100%, respectively. CONCLUSION: CA provides equivalent sensitivity comparable to EA for the recovery of VRE at 48 h incubation, and has additional advantage of being able to differentiate between vancomycine resistant E. faecium and E. faecalis.

Evaluation of the VIDAS CDAB Kits for the Detection of the Clostridium difficile Toxins A and B / 대한임상미생물학회지

BACKGROUND: Since the emergence of variant Clostridium difficile strains that fail to produce detectable toxin A, diagnostic kits targeted to detect toxin A only showed a considerable rate of false negative results. The aim of this study was to evaluate a toxins A and B (toxins A/B) detection kit recently marketed in Korea, and to compare toxin positive rates before and after introduction of the new kit. METHODS: The results of 5,783 toxin A assays performed during the 7-year period from 2001 through 2007 were analyzed and compared them to the toxins A/B assay data of 519 samples obtained from January to June 2008 in a university hospital. An enzyme-linked fluorescent immunoassay for toxins A/B (VIDAS C. difficile Toxin A & B, bioMerieux SA, France: VIDAS CDAB) and PCR for toxin genes A/B were performed directly in 102 stool samples from hospitalized patients. RESULTS: The positive rates of toxin A assays tended downward annually from 2001 to 2007 (16.3%, 17.8%, 13.9%, 11.4%, 13.8%, 8.2%, and 5.8%, respectively), but increased to 12.1% in 2008 after changing to the toxin A/B detection kit. The concordant rate of the VIDAS CDAB kit with the PCR method was 82.4%. Compared to the PCR method, the sensitivity and specificity of the toxin A/B kit were 60.7% and 90.5% respectively. CONCLUSION: Testing kits for C. difficile toxin A only could result in a misdiagnosis more frequently than the testing kit for toxins A/B. The sensitivity of the newly launched toxin A/B detection kit from bioMerieux SA needs to be improved, but it showed a good specificity

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.

Chlamydia trachomatis Antibody in Fitz-Hugh-Curtis Syndrome / 대한진단검사의학회지

BACKGROUND: Fitz-Hugh-Curtis (FHC) syndrome is inflammation of the liver capsule associated with pelvic inflammatory disease. We measured Chlamydia trachomatis antibodies in 30 female patients with acute abdominal pain for diagnosis of FHC-syndrome, and the results were compared with other tests. METHODS: A dual-polymerase chain reaction was used for the detection of C. trachomatis in the cervix, and a micro-immunofluorescence test was performed to measure the antibody to C. trachomatis in serum. Cervical specimens were stained with Gram stain and cultured on chocolate agar for detection of Neisseria gonorrhoeae, and abdominal computed tomography (CT) and pelvic examinations were performed. RESULTS: Of the 30 patients examined, 19 were diagnosed as having FHC-syndromes and 11 abdominal pains without FHC-syndrome. C. trachomatis was detected from one of the five patients studied, and no N. gonorrhoeae was isolated from the patients with FHC-syndrome. High titers of IgG antibody (1:512-1:1,024) to C. trachomatis were demonstrated in all patients with FHC-syndrome. The CT scan revealed perihepatitis in 14 patients with FHC-syndrome. CONCLUSIONS: All patients with FHC-syndrome are associated with C. trachomatis infections, and a high titer of C. trachomatis antibody (IgG) is a very useful marker for FHC-syndrome.

Changing Patterns of Antibiotic Resistance of Helicobacter pylori in Patients with Peptic Ulcer Disease / 대한소화기학회지

BACKGROUND/AIMS: Antibiotic resistance of Helicobacter pylori (H. pylori) is a significant clinical problem because it reduces the efficacy of eradication therapy. The aims of this study were to assess the changing patterns of antibiotic resistance of H. pylori in patients with peptic ulcer diseases and to evaluate the eradication rate in antibiotic resistant H. pylori strains. METHODS: One hundred forty four H. pylori isolates obtained from 466 patients with peptic ulcer disease between June 2001 and December 2005 were examined for antimicrobial resistance. The minimum inhibitory concentration (MIC) of metronidazole was determined by modified broth microdilution method (mBMD) and E test. MICs of clarithromycin and amoxicillin were determined by mBMD, E test, and disc diffusion test. The breakpoints for metronidazole, clarithromycin, and amoxicillin resistance were defined as >8microgram/mL, >1microgram/mL, and > or =1microgram/mL, respectively. RESULTS: Resistance to metronidazole and clarithromycin was detected in 34.7% and 16.7% of H. pylori isolates, respectively. During the recent 5-year study period, amoxicillin-resistant rate of H. pylori was 11.8%, and multi-drug resistance rate of H. pylori was 16.7%. The eradication rate of clarithromycin containing triple therapies was low (7.8%) in clarithromycin-resistant H. pylori strains. CONCLUSIONS: The proportions of clarithromycin-resistant H. pylori strains have increased significantly over the last 5-years. There is an increasing tendency for the emergence of strains with multi-drug resistance. The increase in clarithromycin-resistant strains results in a decrease in eradication rate for H. pylori. In areas with high clarithromycin resistance, new alternative first-line treatment combination should be considered.