• Journal of Microbiology and Biotechnology
• /
• v.24 no.3
• /
• pp.421-426
• /
• 2014

To characterize the extended-spectrum beta-lactamases (ESBLs) in diarrheagenic Escherichia coli from Korea in 2008-2011, we screened seven enterotoxigenic E. coli (ETEC) and one enteroaggregative E. coli (EAEC) that produce ESBLs from a nationwide survey. All eight isolates produced CTX-M-type ESBLs, including CTX-M-12 (n = 4), CTX-M-14 (n = 2), and CTX-M-15 (n = 2). PCR-based replicon typing indicated that the $bla_{CTX-M-12}$ genes of four ETEC isolates were carried on a conjugative IncF plasmid, whereas the $bla_{CTX-M-14}$ of one EAEC was located on an IncK plasmid. This is the first report of the occurrence of $bla_{CTX-M}$ genes in clinical isolates of EAEC in Korea. The ESBL-producing isolates were shown to be different based on pulsed-field gel electrophoresis and multilocus sequence typing, whereas the four isolates with CTX-M-12 were clonally related. These observations raise an alarm for the spread of plasmid-mediated resistance to ESBL among diarrheagenic E. coli.

• Korean Journal of Clinical Laboratory Science
• /
• v.44 no.2
• /
• pp.81-85
• /
• 2012

This study was undertaken to evaluate phenotypic and genotypic methods for detection of Metallo-Beta-Lactamases (MBLs) among nosocomial Pseudomonas aeruginosa. Of the 50 P. aeruginosa isolates from clinical specimens, 20 were evaluated for carbapenem resistance and screened for MBL by double-disk synergy test and combined-disk test. Nineteen strains (95%) were found to be MBL producers among the 20 P. aeruginosa. MBL positives were further confirmed by Polymerase Chain Reaction (PCR). For the IMP and VIM types of MBLs, PCR analysis was performed on 19 of the 20, and 10 were positive for VIM MBL type. This study reports the validation of a simple and accurate MBL detection method that can be easily incorporated into the daily routine of a clinical laboratory. Early detection of MBL-carrying organisms, including those with susceptibility to carbapenems, is of paramount clinical importance, as it allows rapid initiation of strict infection control practices as well as therapeutic guidance for confirmed infection.Key Words : Hepatitis A virus (HAV), Anti-HAV, Hospital workers, Prevalence, Vaccination

• Clinical and Experimental Pediatrics
• /
• v.48 no.10
• /
• pp.1107-1115
• /
• 2005

Purpose : An outbreak of ESBL-producing Shigella sonnei enteritis was unprecedented not only in Korea but throughout the world in the past. We intended to devise a management guideline for ESBL-producing shigellosis based on analysis of clinical manifestations and response to therapy. Methods : We analyzed 103 patients who were admitted to the hospital with acute GI symptoms and were shown positive result for S. sonnei on stool culture. We performed sensitivity test to the antibiotics and DNA sequencing of ESBL gene in the isolated S. sonnei colonies. In addition, we retrospectively analyzed their clinical characteristics, laboratory results, and clinical and microbiological responses to the antibiotics. Results : Among the clinical manifestations, fever was the most frequent(96.1%), followed by diarrhea(93.2%), abdominal pain(76.7%), headache(71.8%), vomiting(65.0%), and nausea(41.7%). The fever was sustained for average of 2.0 days and diarrhea for 3.9 days. Watery diarrhea was the most common(69%) followed by mucoid(26%), and bloody stool(5%). On peripheral blood smear, leukocytosis was noted in 53.4% of patients, and 78.6% of patients tested positive for serum CRP response. On stool direct smear, 11.7% of patients showed more than 50 WBCs/HPF, and 9.7% of patients between 5 to 20 WBCs/HPF. Stool occult blood was positive in 71% of patients. Production of CTX-M-14 type ESBL was reported for all S. sonnei strains isolated from this outbreak. Microbiological eradication rates to various antibiotics were as follows : 100%(9/9) to ciprofloxacin, 100% 5/5) to azithromycin, 6.9%(5/72) to cefdinir, 0%(0/8) to ceftriaxone, 12.5%(1/8) to ceftizoxime, 0%(0/ 8) to TMP/SMX, 42.9%(3/7) to ampicillin/sulbactam, 20%(1/5) to amoxicillin/clavulanic acid, and 68.8 %(11/16) to imipenem/cilastatin. Conclusion : It is presumed that azithromycin can be an attractive option for the treatment of ESBL-producing S. sonnei enteritis in pediatric population, given its cost-effectiveness and safety. Although ciprofloxacin is another cost-effective agent, its use in pediatric population may be a bit too premature.

• Tuberculosis and Respiratory Diseases
• /
• v.74 no.2
• /
• pp.63-69
• /
• 2013

Background: Aiming to improve outcome of lung transplantation (LTx) patients, we reviewed risk factors and treatment practices for the LTx recipients who experienced respiratory infection in the late post-LTx period (>1 month after LTx). Methods: We analyzed the clinical data of 48 recipients and donors from 61 LTx, who experienced late respiratory infections. Late respiratory infections were classified according to the etiology, time of occurrence, and frequency of donor-to-host transmission or colonization of the recipient prior to transplantation. Results: During the period of observation, 42 episodes of respiratory infections occurred. The organisms most frequently involved were gram (-) bacteria: Acinetobacter baumannii (n=13, 31.0%), Pseudomonas aeruginosa (n=7, 16.7%), and Klebsiella pneumoniae (n=4, 10.0%). Among the 42 episodes recorded, 14 occurred in the late post-LTx period. These were bacterial (n=6, 42.9%), fungal (n=2, 14.3%), viral (n=4, 28.5%), and mycobacterial (n=2, 14.3%) infections. Of 6 bacterial infections, 2 were from multidrug-resistant (MDR) A. baumannii and one from each of MDR P. aeruginosa, extended spectrum ${\beta}$-lactamase (+) K. pneumoniae, methicillin-resistant Staphylococcus aureus and Streptococcus pneumoniae. Infection-related death occurred in 6 of the 14 episodes (43%). Conclusion: Although the frequency of respiratory infection decreased sharply in the late post-LTx period, respiratory infection was still a major cause of mortality. Gram (-) MDR bacteria were the agents most commonly identified in these infections.

• Biomedical Science Letters
• /
• v.21 no.2
• /
• pp.84-91
• /
• 2015

To provide guidelines for the empirical treatment of urinary tract infections, we observed annual changes in the occurrence frequency and antimicrobial susceptibility of urinary isolates in a university hospital in the Chungbuk province, South Korea, over a period of 10 years (2004~2013). Escherichia coli (38.2%), Enterococcus faecalis (11.7%), Klebsiella pneumoniae (7.3%), Pseudomonas aeruginosa (4.3%), E. faecium (4.3%), and Staphylococcus aureus (4.1%) were commonly isolated urinary pathogens. The prevalence of E. coli, E. faecium and Streptococcus agalactiae were significantly higher in females (P < 0.001), whereas E. faecalis, P. aeruginosa and S. aureus were significantly more common in male patients (P < 0.001). E. coli mostly frequently showed resistance to ampicillin (67.94%), followed by trimethoprim/sulfamethoxazole (36.06%) and ciprofloxacin (26.84%). Over the studied time period, resistance rates of E. coli to ciprofloxacin significantly increased (20.44% to 33.55%). Moreover, extended-spectrum $\beta$-lactamase (ESBL) producing isolates also significantly increased in E. coli (4.2% to 18.3%) and K. pneumoniae (9.6% to 26.9%). In addition, the proportion of vancomycin-resistant Enterococcus facium (VRE) also increased (15.7% to 25.0%). In conclusion, over the last 10 years, the proportions of ciprofloxacin resistant E. coli and multidrug-resistant bacteria, such as ESBL and VRE have significantly increased. This trend must be strictly controlled and demonstrates the need for more updated guidelines for the treatment of urinary tract infections.

• Childhood Kidney Diseases
• /
• v.21 no.2
• /
• pp.121-127
• /
• 2017

Purpose: The aim of this study was to determine the prevalence of antibiotic susceptibility and resistance of Escherichia coli in urinary tract infections (UTIs) in children. Methods: We retrospectively reviewed the clinical records of 212 inpatients aged 18 years or younger with UTIs treated at the Pediatric Department of Dongguk University Gyeongju Hospital between January 2008 and December 2016. For comparison, patients were divided into three groups according to age as follows: group 1, ${\leq}1$ month; group 2, >1 month to ${\leq}12$ months; and group 3, ${\geq}13$ months. The antibiotic resistance rates from January 2008 to December 2012 (study period 1) and from January 2013 to December 2016 (study period 2) were analyzed statistically by group. Results: As the patient age increased, the antibiotic resistance rate to ampicillin (P=0.013), levofloxacin (P=0.050), piperacillin/tazobactam (TZP) (P<0.001), and trimethoprim/sulfamethoxazole (P=0.002) increased. The frequency of extended spectrum beta-lactamase producing E. coli showed a significant difference from 5 cases (4.6%) in study period 1 and 16 cases (15.8%) in study period 2 (P=0.007). The antibiotic resistance rate of E. coli was compared between the two time periods and we found that the antibiotic resistance rate to cefotaxime was significantly increased from 5.4% to 16.8% (P=0.008) and that to TZP was significantly decreased from 40.5% to 7.9% (P<0.001). Conclusion: Over the past 9 years, the resistance rate to cefotaxime has increased but the resistance rate to TZP has decreased. Thus, it is important to continue to investigate the antibiotic resistance rates of bacteria in the community.

• Journal of Microbiology and Biotechnology
• /
• v.20 no.1
• /
• pp.146-152
• /
• 2010

Streptomyces clavuligerus NRRL3585 produces a clinically important $\beta$-lactamase inhibitor, clavulanic acid (CA). In order to increase the production of CA, the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene (gap) was deleted in S. clavuligerus NRRL3585 to overcome the limited glyceraldehyde-3-phosphate pool; the replicative and integrative expressions of ccaR (specific regulator of the CA biosynthetic operon) and claR (Lys-type transcriptional activator) genes were transformed together into a deletion mutant to improve clavulanic acid production. We constructed two recombinant plasmids to enhance the production of CA in the gap1 deletion mutant of S. clavuligerus NRRL3585: pHN11 was constructed for overexpression of ccaR-claR, whereas pHN12 was constructed for their chromosomal integration. Both pHN11 and pHN12 transformants enhanced the production of CA by 2.59-fold and 5.85-fold, respectively, compared with the gap1 deletion mutant. For further enhancement of CA, we fed the pHN11 and pHN12 transformants ornithine and glycerol. Compared with the gap1 deletion mutant, ornithine increased CA production by 3.24- and 6.51-fold in the pHN11 and pHN12 transformants, respectively, glycerol increased CA by 2.96- and 6.21-fold, respectively, and ornithine and glycerol together increased CA by 3.72- and 7.02-fold, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.47 no.3
• /
• pp.220-226
• /
• 2014

Sixty-seven Vibrio parahaemolyticus isolates from surface seawater from the Wando area, on the southern coast of Korea, were analyzed for their susceptibility to 15 different antimicrobials and the presence of virulence genes. According to the disk diffusion susceptibility test, all of the strains studied were resistant to ampicillin and oxacillin, while decreasing percentages were resistant to vancomycin (64.2%), streptomycin (56.7%), amikacin (31.3%), kanamycin (22.3%), cephalothin (20.9%), erythromycin (10.4%), ciprofloxacin (4.5%), and tetracycline (3.0%). All of the strains were susceptible to five antimicrobials: chloramphenicol, gentamycin, nalidixic acid, sulfamethoxazole/trimethoprim, and trimethoprim. Fifty-nine isolates (88.1%) were resistant to three or more classes of antimicrobial and defined as multidrug resistant, and two strains were resistant to seven antimicrobial agents. The minimum inhibitory concentration (MIC) of the 67 V. parahaemolyticus isolates to ampicillin and oxacillin ranged from 512-2,048 and $64-512{\mu}g/mL$, respectively. All 67 isolates were also examined for the presence of the tdh and trh virulence genes using the polymerase chain reaction (PCR). However, no isolates possessed either tdh or trh. The VPA0477 (${\beta}$-lactamase) gene, present in all of the tested strains, was validated as a new specific marker gene in PCR assays for the accurate detection and identification of V. parahaemolyticus.

• Clinical and Experimental Pediatrics
• /
• v.60 no.7
• /
• pp.221-226
• /
• 2017

Purpose: Escherichia coli sequence type (ST) 131, a multidrug-resistant clone causing extraintestinal infections, has rapidly become prevalent worldwide. However, the epidemiological and clinical features of pediatric infections are poorly understood. We aimed to explore the characteristics of ST131 Escherichia coli isolated from Korean children with urinary tract infections. Methods: We examined 114 uropathogenic E. coli (UPEC) isolates from children hospitalized at Chung-Ang University Hospital between 2011 and 2014. Bacterial strains were classified into STs by partial sequencing of seven housekeeping genes (adk, fumC, gyrB, icd, mdh, purA, and recA). Clinical characteristics and antimicrobial susceptibility were compared between ST131 and non-ST131 UPEC isolates. Results: Sixteen UPEC isolates (14.0%) were extended-spectrum ${\beta}-lactamase$ (ESBL)-producers; 50.0% of ESBL-producers were ST131 isolates. Of all the isolates tested, 13.2% (15 of 114) were classified as ST131. There were no statistically significant associations between ST131 and age, sex, or clinical characteristics, including fever, white blood cell counts in urine and serum, C-reactive protein, radiologic abnormalities, and clinical outcome. However, ST131 isolates showed significantly lower rates of susceptibility to cefazolin (26.7%), cefotaxime (40.0%), cefepime (40.0%), and ciprofloxacin (53.3%) than non-ST131 isolates (65.7%, 91.9%, 92.9%, and 87.9%, respectively; P<0.001 for all). ESBL was more frequently produced in ST131 (53.3%) than in non-ST131 (8.1%) isolates (P<0.01). Conclusion: ST131 E. coli isolates were prevalent uropathogens in children at a single medical center in Korea between 2011 and 2014. Although ST131 isolates showed higher rates of antimicrobial resistance, clinical presentation and outcomes of patients were similar to those of patients infected with non-ST131 isolates.

• Journal of Microbiology and Biotechnology
• /
• v.17 no.9
• /
• pp.1538-1545
• /
• 2007

Clavulanic acid (CA) is an inhibitor of ${\beta}$-lactamase that is produced from Streptomyces clavuligerus NRRL3585 and is used in combination with other antibiotics in clinical treatments. In order to increase the production of CA, the replicative and integrative expressions of ccaR (encoding for a specific regulator of the CA biosynthetic operon) and cas2 (encoding for the rate-limiting enzyme in the CA biosynthetic pathway) were applied. Six recombinant plasmids were designed for this study. The pIBRHL1, pIBRHL3, and pIBRHL13 were constructed for overexpression, whereas pNQ3, pNQ2, and pNQ1 were constructed for chromosomal integration with ccaR, cas2, and ccaR-cas2, respectively. All of these plasmids were transformed into S. clavuligerus NRRL3585. CA production in transformants resulted in a significantly enhanced amount greater than that of the wild type, a 2.25-fold increase with pIBRHLl, a 9.28-fold increase with pNQ3, a 5.06-fold increase with pIBRHL3, a 2.93-fold increase with pNQ2 integration, a 5.79-fold increase with pIBRHLl3, and a 23.8-fold increase with pNQ1. The integrative pNQl strain has been successfully applied to enhance production.