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

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

• Childhood Kidney Diseases
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• v.23 no.1
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• pp.29-35
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• 2019

Purpose: We aimed to determine characteristics of host, causative organisms, and antibiotic susceptibility of bacteria in pediatric patients with UTI living in metropolitan area of Korea. Methods: Retrospective investigation was done for the causative organisms of UTI in 683 pediatric cases treated at Ajou University Hospital from 2012 to 2017. Patients were classified into Escherichia coli and non-E. coli group, where E. coli group was subdivided into ESBL(+) and ESBL(-) groups based on whether the bacteria could produce extended spectrum beta-lactamase (ESBL). Antibiotic susceptibility of the causative organism was also determined. Results: A total of 683 UTIs occurred in 550 patients, of which 463 (67.8%) were first-time infection and 87 (32.2%) were recurrent ones (2-7 recurrences, 2.52 average), and 64.9% were male and 35.1% were female. The most common causative organism was E. coli (77.2%) and ESBL(+) E. coli was found in 126 cases. The susceptibility of E. coli to 3rd or 4th generation cephalosporin was relatively higher than that to ampicillin or amoxicillin/clavulanic acid. ESBL(+) E. coli showed higher resistance rate to 3rd or 4th generation cephalosporin than ESBL(-) E. coli. Conclusion: New treatment guideline should be considered due to the incidence of ESBL(+) E. coli increased up to one quarter of UTI cases.

• Korean Journal of Veterinary Service
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• v.37 no.1
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• pp.19-27
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• 2014

This study was conducted to investigate the antimicrobial resistance, presence of ${\beta}$-lactamase genes and integrons in 83 ESBL-producing Escherichia coli isolated from Nakdong river and Geumho river in Daegu. Among the ${\beta}$-lactam antimicrobials, all isolates were resistant to ampicillin, cephalothin, cefamandole and cefotaxime, followed by piperacillin (98.8%), ampicillin/sulbactam (86.7%), aztreonam (60.2%) and cefepime (59.0%), whereas resistance to piperacillin/tazobacram, ticarcillin/clavulanic acid and cefoxitin was less than 30%. Many of the ESBL-producing Escherichia coli were also resistant to non-${\beta}$-lactams antimicrobials such as nalidixic acid (83.1%), sulfonamides (72.3%), ciprofloxacin (62.7%) and gentamicin (38.6%). All isolates showed resistance to seven or more antimicrobial agents. The most frequently detected gene was $bla_{TEM+CTX-M}$ (49.4%), followed by $bla_{CTX-M}$ (27.7%), $bla_{TEM}$ (6.0%) and $bla_{OXA}$ (1.2%). But $bla_{SHV}$ was not found. Class 1 integrons were found in 61.4% (51 isolates) of isolates, however, class 2 and 3 integrons were not detected. The results showed water from Nakdong river and Geumho river is contaminated with ESBL-producing E. coli isolates. These results suggest the need for further investigation of antibiotic resistant bacteria to prevent public health impacts in the water environment.

• Urogenital Tract Infection
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• v.13 no.3
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• pp.72-78
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• 2018

Purpose: This retrospective study was undertaken to investigate whether increasing amikacin dosage for ciprofloxacin prophylaxis in patients with fluoroquinolone (FQ)-resistant rectal flora reduce infectious complications after transrectal ultrasound-guided prostate biopsy (TRUSPB). Materials and Methods: A total of 430 patients with FQ-resistant rectal flora based on rectal swab cultures were divided into two groups. Patients in both groups were administered ciprofloxacin (400 mg, intravenous [IV], twice daily) on the same day as TRUSPB and one day after biopsy. However, whereas group 1 patients (n=202) were administered a single injection of amikacin (1 g, IV) one hour before TRUSPB, patients in group 2 (n=228) were administered two injections of amikacin (1 g, IV) before one hour TRUSPB and again on the day after TRUSPB. Results: Of the 430 study subjects, 129 (30.0%) showed extended-spectrum beta-lactamase (ESBL) positivity. The overall incidence rate of infectious complications was 2.8% (12/430). Infectious complication rates were 4.0% (8/202) in group 1 and 1.3% (3/228) in group 2 (p=0.075). Urinary tract infection and acute prostatitis were more frequent in group 1 (3.5% vs. 0.4%, p=0.029). Infectious complication rates in ESBL negative patients were 3.4% (5/145) in group 1 and 1.3% (2/156) in group 2, whereas those in ESBL positive patients were 7.0% (4/57) in group 1 and 1.4% (1/72) in group 2. Conclusions: Increasing the dosage of amikacin for ciprofloxacin prophylaxis reduce infectious complications in patients with FQ-resistant rectal flora and to be more effective in ESBL positive patients with FQ-resistant rectal flora.

• Journal of Food Hygiene and Safety
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• v.29 no.1
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• pp.47-52
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• 2014

This study was performed to evaluate antimicrobial resistance of food-borne pathogens isolated from retail meat in Korea. A total of 157 samples of beef, pork, and chicken were collected and analyzed for E. coli, Salmonella, Campylobacter. Resistances to tetracycline were declined in accord with reduced usage of tetracycline in live stock production. E. coli stains from chicken meat had higher multi-drug resistance ratio than strains from other meat. One extended spectrum beta lactamase (ESBL) producing E. coli and two ESBL producing Salmonella were identified in this study. ESBL producing Salmonella strains were confirmed to carry CTX-M-1 type genes.

• Clinical and Experimental Pediatrics
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• v.64 no.6
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• pp.293-300
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• 2021

Background: Understanding the epidemiology and prevalence of febrile urinary tract infection (fUTI) in children is important for risk stratification and selecting appropriate urine sample collection candidates to aid in its diagnosis and treatment. Purpose: This study aimed to analyze the epidemiology, etiology, and changes in antibiotic susceptibility patterns of the first fUTI in children. Methods: This retrospective observational cohort study included children younger than 19 years of age who were diagnosed and treated for their first fUTI in 2006-2016. Electronic medical records were analyzed and radiologic images were evaluated. Results: A total of 359 patients (median age, 5.1 months; interquartile range, 3.0-10.5 months) fit the inclusion criteria; of them, 78.0% (n=280) were younger than 12 months old. The male to female ratio was 5.3:1 for patients aged 0-2 months, 2.1:1 for those 3-5 months, and 1.6:1 for those 6-11 months. Beyond 12 months of age, there was a female predominance. Escherichia coli was the leading cause (83.8%), followed by Enterococcus species (6.7%), and Klebsiella pneumoniae (3.6%). Significant yearly increases in the proportions of multidrug-resistant strains (P<0.001) and extended-spectrum beta-lactamase (ESBL) producers (P<0.001) were observed. In patients with vesicoureteral reflux (VUR), the overall recurrence rate was 53.6% (n=15). A significantly higher recurrence rate was observed when the fUTI was caused by an ESBL versus non-ESBL producer (75.0% vs. 30.0%, P=0.03). Conclusion: fUTI was most prevalent in children younger than 12 months of age and showed a female predominance in patients older than 12 months of age. The proportion of ESBL producers causing fUTI is increasing. Carbapenems, rather than noncarbapenems, should be considered for treating fUTI caused by ESBL-producing enteric gram-negative rods to reduce short-term recurrence rates in children with VUR.

• Journal of the Korea Convergence Society
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• v.6 no.5
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• pp.77-84
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• 2015

This study was conducted to investigate the characteristics of antibiotic resistant E. coli. its antibiotic susceptibility and pathogenicity were analyzed via molecular convergence technique, for the relationship of antibiotic susceptibility and pathogenicity. The 60 isolated strains consisted of ESBL(+)(8) and ESBL(-)(52) strains. The ESBL(+)(8) strains consisted of 2 strains without a pathogenic gene, stb(3), flich7(1), and flich7-eae(2). The ESBL(-)(52) strains consisted of 26 strains without a pathogenic gene, stx1(3), stb(10), flich7(2), eae(2), stx1-flich7(2), stx1-stb(4), flich7-stb(2), and flich7-stb-eae(1). In conclusion, antibiotic resistance is increasingly, Focused on molecular convergence, showed the correlation of pathogenicity with antibiotic resistance was poor. However, It will be able to find the exact pathogenic factor in the future through convergence technique including the analysis of virulence genes.

• Korean Journal of Veterinary Service
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• v.42 no.1
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• pp.17-24
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• 2019

The aim of this study was to investigate the prevalence and characterization of plasmid-mediated quinolone resistance (PMQR) gene in 79 Enterobacteriaceae isolated from dogs and cats. Of 79 isolates, PMQR genes were found in 10 (12.7%) isolates, including aac(6')-lb-cr, qnrB, qnrS and qnrA detected alone or in combination in 8 (10.1%), 4 (5.1%), 2 (2.5%) and 1 (1.3%) isolates, respectively. Interestingly, two qnrS genes were detected in nalidixic acid and ciprofloxacin susceptible isolates. Extended-spectrum ${\beta}$-lactamase (ESBL) was detected in 90% (9 isolates) of PMQR positives isolates. Among ESBL genes, CTX-M, TEM and SHV were detected in 9, 8 and 3 isolates, respectively. Almost all PMQR genes were detected in co-existence with ESBL genes. All PMQR positives isolates were multidrug resistance (i.e. resistant to five or more antibiotics). qepA, OXA and CMY-2 genes were not found. The six transconjugants were obtained by conjugation experiment. The aac(6')-lb-cr, qnrB and qnrS were co-transferred with CTX-M, TEM and/or SHV, whereas qnrA was not observed among transconugants. This is the first report of the presence of aac(6')-lb-cr and qnrA gene among Enterobacteriaceae isolates from dogs in Korea. The prudent use of antimicrobials and continuous monitoring for companion animals are required.

• Tuberculosis and Respiratory Diseases
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• v.49 no.1
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• pp.72-81
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• 2000

Backgrounds : Authors evaluated the quantitative culture of bronchoalveolar lavage fluid(BALF) in patients who were being treated with antimicrobial agents and the characteristics of isolated microorganism. Method : A prospective study was done with 25 patients under mechanical ventilation and antimicrobial treatment in ICU and NCU of Yongdong Severance Hospital from Apr. to Sep. 1999. Patients were classified into two groups: control group (n=5) and patients with VAP (n=20). The threshold of quantitative culture of BAL fluid in the diagnosis of VAP was $10^4$ cfu/ml. Results : 1) In gram staining of BALF, one patient in the control group and four in the VAP group showed positive results. Quantitative culture of BALF showed no organisms in the patients in the control group and in 9 VAP patients. Therefore the overall sensitivity was 43.8%. 2) Frequency of isolated organisms cultured above diagnostic threshold was in the following order: E. cloaclae, S. aureus, K. pneumoniae, and A. baumani. S. aureus and Staphylococcus coagulase(-) were a11 resistant to oxacillin. Seven out of 10 isolated G (-) organisms were suspected to be organisms producing extended spectrum $\beta$-lactamase (ESBL). 3) The concurrence between gram staining of sputum aspiration and that of BALF was only in 1 case. And the concurrence of culture results was observed in 3 cases. Conclusion : The sensitivity of gram staining and quantitative culture of BALF from patients under antibiotic therapy and the concordance rate between conventional tracheal aspiration and BAL were low, facts which were important in interpretation the data. Since the frequency of drug resistance organisms was not different from that of foreign data, antibiotics must be prudently selected and used.