• The Journal of the Korean Society for Microbiology
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• v.22 no.3
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• pp.241-250
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• 1987

A total 64 strains of Escherichia coli including 38 strains of urinary tract infection and 26 strains from other clincal sources were studied for several properties related to the virulence markers of organisms. Urinary isolates(76.3%) showed higher frequency of mannose resistant hemagglutination(MRHA) wi th human erythrocytes(A type, $Rh^+$) than the strains of control group isolated from other sources(34.6%). Seventeen strains(44.4%) of urinary isolates and 2 strains(7.7%) of control group showed hemolysis on blood agar plate. There was no significant difference in MIC's of 23 drugs between both groups of urinary isolates and control group. But they showed high frequency of resistance to ampicillin, carbenicillin, piperacillin, kanamycin, and trimethoprim, but were very susceptible to cefotaxime, moxalactam, ceftizidime, imipenem, and norfloxacine. Fourteen strains(36.8%) of urinary isolates and 10 strains(38.5%) of control group showed conjugally transferable resistance conferred to R plasmids. The urinary isolates carried one or more to 6(mean 3.4) plasmids of approximate molecular weight ranged 3.1 to 94 megadalton(Mdal) and strains of control group carried 2 to 5(mean 3.8) plasm ids of size ranged 3.6 to 130 Mdal. The size of conjugally transferable R plasmid identified with transconjugants ranged 32 to 130 Mdal.

• Microbiology and Biotechnology Letters
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• v.49 no.2
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• pp.239-248
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• 2021

The emergence of multidrug-resistant Acinetobacter baumannii has partly increased treatment failure and patient mortality. Class D β-lactamases is an important mechanism of resistance to beta-lactam antibiotics in this species. This study aimed to investigate the relationship between the presence oxacillinase gene and genetic fingerprints of A. baumannii isolates from the intensive care unit of an Egyptian tertiary care hospital. One hundred and twenty A. baumannii clinical isolates were collected. Multiplex PCR was performed to detect genes encoding oxacillinases (OXA-23, OXA-24, OXA-51, OXA-58 and OXA-143). Molecular typing of all collected isolates was performed using random amplified polymorphic DNA (RAPD)-PCR assay. Out of 120 examined isolates, 92, 88 and 84% were resistant to ertapenem, imipenem and meropenem, respectively. The species-specific, commonly present OXA-51 gene was found in all isolates while OXA-23 showed a high prevalence of 88% of isolates. OXA-24 and OXA-143 genes were detected in 3% and 1% of isolates, respectively. No OXA-58 gene was detected. Five clusters consisting of 19 genotypes were detected using RAPD-PCR. Genotype A was the most prevalent, it was observed in 62% of the isolates followed by genotype B (12%). These results revealed that genotypes A and B are common in the hospital. Results also demonstrate that RAPD-PCR is a rapid and reliable method for studying the clonal similarity among A. baumannii isolated from different clinical specimens.

• Microbiology and Biotechnology Letters
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• v.50 no.1
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• pp.147-156
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• 2022

Urinary tract infections (UTIs) are one of the most common infections in different age groups, including children. Bacteria are the main etiological agents of UTIs. The aim of the present study was to isolate, identify, and determine the antibiotic susceptibility of bacteria isolated from children with UTIs from Baghdad, Iraq. Three hundred and two urine samples were collected from children aged 6 months to 12 years. The samples were cultured on blood agar and MacConkey agar. The selected colonies were subjected to biochemical tests and antibiotic susceptibility analysis using the Vitek^® 2 Compact automated microbial identification system. In this sample, 299 bacteria were identified, of which, 267 were gram-negative bacteria, and 32 were gram-positive bacteria. Escherichia coli (56%) was the most commonly isolated gram-negative bacteria, followed by Pseudomonas aeruginosa (14%), Enterobacter spp. (10.48%), Klebsiella pneumoniae (9.36%), Proteus spp. (7.8%), Acinetobacter baumannii (1.5%), and Morganella morganii (0.37%). Enterococcus faecalis (62.5%) was the most commonly detected gram-positive bacteria, followed by Staphylococcus aureus (37.5%). E. coli and P. aeruginosa were the most antibiotic-resistant bacteria. Among the tested antibiotics, meropenem showed 100% sensitivity, followed by imipenem (97.4%), amikacin (91.8%), and tobramycin (83.5%). In contrast, the high frequencies of resistance were observed with cefixime (93.2%), cefotaxime (78.7%), and ceftriaxone/cefotaxime (71.2%). In conclusion, carbapenems and aminoglycosides are highly recommended for the empirical treatment of UTIs, while, Quinolones, penicillins, and cephalosporins are not suggested. Frequent antibiotics susceptibility testing are warranted to determine the resistance pattern of UTI bacteria.

• Korean Journal of Veterinary Service
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• v.44 no.4
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• pp.209-216
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• 2021

This study was aimed to investigate occurrence and the antimicrobial resistance of Escherichia coli isolates obtained from the feces of wild birds in Daegu. In total, 98 E. coli isolates (17.9%) were obtained from 547 fecal samples of wild birds. The E. coli carried by the birds showed a relatively high rate of antimicrobial resistance to tetracycline (27.6%) and ampicillin (21.4%). Drug resistance of the isolates to the others (penicillins, cephems, carbapenems, aminoglycosides, quinolones, sulfonamides and phenicols) resulted in the rates less than 20%, and all isolates were susceptible to imipenem, ciprofloxacin, cefotetan, and amikacin. Approximately, 45% E. coli among the isolates were resistant to one or more drugs tested. The higher rate of tetracycline resistance led us to determine the prevalence of the tet genes (tetA, tetB, tetC, tetD and tetE) in the tetracycline-resistant E. coli isolates by using PCR. All isolates of the tetracycline-resistant E. coli contained at least one or more of these tet genes examined. The most prevalent one was tetA (59.3%), and followed by tetB (7.4%) when tested with the selected 5 tet genes. Except tetA and tetB, however, the remaining tet genes (tetC, tetD, and tetE) tested were not found in this study. Nine isolates among the tetracycline-resistant E. coli contained the two (tetA and tetB) determinants of tetracycline resistance, simultaneously.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.5
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• pp.626-633
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• 2023

Vibrio spp. are aquatic bacteria that are ubiquitous in warm estuarine and marine environments. Especially, V. vulnificus and V. cholerae are currently known to cause potentially fatal infections in humans. This study investigated the distribution and antibiotic resistance of V. vulnificus and V. cholerae isolated from coastal areas of Gyeongsangnam-do in 2022. A total of 252 samples of water, shellfish and coastal sediment were collected from 7 locations along the coast, and 124 samples of fishery products were collected from markets. Among the 252 samples, forty-four V. vulnificus (11.7%) and fourteen V. cholerae non-O1/non-O139 (3.7%), none of which carried the ctx gene, were isolated. Out of the 124 samples, 6 (4.8%) tested positive for V. vulnificus and V. cholerae was not detected. The isolation rates of V. vulnificus and V. cholerae showed a significant correlation with environmental factors such as seawater temperature and salinity. In an antibiotic resistance test, V. vulnificus was susceptible to amikacin, gentamicin, imipenem trimethoprim/sulfamethoxazole, and ciprofloxacin, but resistant to cefoxitin (100.0%), followed by tetracycline (9.1%). Multidrug resistance was also observed. Continuous monitoring of Vibrio pathogens with water temperature and salinity is expected to help reduce the outbreaks, and rational use of antibiotic agents is needed to prevent the accession of antibiotic-resistant microorganisms in aquatic ecosystems.

• Clinical and Experimental Pediatrics
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• v.50 no.1
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• pp.56-64
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• 2007

Purpose : This study was performed to identify the etiologic agents and antimicrobial susceptibility patterns of organisms responsible for bloodstream infections in pediatric cancer patients for guidance in empiric antimicrobial therapy. Methods : One hundred and ninety-seven episodes of bloodstream infections that developed in 128 pediatric cancer patients were analyzed, which were identified at the Seoul National University Children's Hospital during a 4 year-period from 2002 to 2005. Results : A total of 214 pathogens was isolated, of which 64.0 percent were gram-negative, 31.3 percent were gram-positive bacteria, and 4.7 percent were fungi. The most common pathogens were Klebsiella spp. (21 percent) and Escherichia coli (16.8 percent), and coagulase-negative staphylococci (CNS, 7.9 percent) and viridans streptococci (7.5 percent) emerged as important pathogens. Neutropenic patients were more often associated with gram-negative bacteria than non-neutropenic patients (67.5 percent vs. 51.1%, P=0.018) and patients with central venous catheters were more often associated with CNS and viridans streptococci than those without. Resistance rates of gram-positive bacteria to penicillin, oxacillin and vancomycin were 83.3 percent, 48.5 percent and 0.5 percent, respectively, and those of gram-negative bacteria to cefotaxime, piperacillin/tazobactam, imipenem, gentamicin and amikacin were 24.1 percent, 17.2 percent, 6.6 percent, 21.6 percent, and 14.2 percent, respectively. Gram-negative bacteremias were more often associated with intensive care than gram-positive bacteremias (26.5 percent vs. 10.3 percent, P=0.016), and patients with catheters were more often associated with intensive care (34.4 percent vs. 10.8 percent, P<0.001) and higher fatality rate (16.7 percent vs. 4.8 percent, P=0.012) than those without. Conclusion : This study revealed that gram-negative bacteria are still a dominant organism in bloodstream infections, especially in neutropenic patients, and confirmed that gram-positive bacteria are emerging as important etiological agents in bloodstream infections of pediatric hemato-oncologic patients.

• Pediatric Infection and Vaccine
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• v.19 no.3
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• pp.131-140
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• 2012

Purpose : This study was performed to identify the etiologic agents and antimicrobial susceptibility patterns of organisms responsible for bloodstream infections in pediatric cancer patients for guidance in empiric antimicrobial therapy. Methods : A 5-year retrospective study of pediatric hemato-oncologic patients with bacteremia in Seoul National University Children's Hospital, from 2006 to 2010 was conducted. Results : A total of 246 pathogens were isolated, of which 63.4% (n=156) were gram-negative, bacteria 34.6% (n=85) were gram-positive bacteria, and 2.0% (n=5) were fungi. The most common pathogens were Klebsiella spp. (n=61, 24.8%) followed by Escherichia coli (n=31, 12.6%), coagulase-negative staphylococci (n=23, 9.3%), and Staphylococcus aureus (n=22, 8.9 %). Resistance rates of gram-positive bacteria to penicillin, oxacillin, and vancomycin were 85.7%, 65.9%, and 9.5%, respectively. Resistance rates of gram-negative bacteria to cefotaxime, piperacillin/tazobactam, imipenem, gentamicin, and amikacin were 37.2%, 17.1%, 6.2%, 32.2%, and 13.7%, respectively. Overall fatality rate was 12.7%. Gram-negative bacteremia was more often associated with shock (48.4% vs. 11.9%, P<0.01) and had higher fatality rate than gram-positive bacteremia (12.1% vs. 3.0%, P=0.03). Neutropenic patients were more often associated with shock than non-neutropenic patients (39.6 % vs. 22.0%, P=0.04). Conclusion : This study revealed that gram-negative bacteria were still dominant organisms of bloodstream infections in children with hemato-oncologic diseases, and patients with gram-negative bacteremia showed fatal course more frequently than those with gram-positive bacteremia.

• Clinical and Experimental Pediatrics
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• v.49 no.5
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• pp.500-506
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• 2006

Purpose : We evaluated an outbreak of Serratia marcescens infections in 24 neonates in a neonatal intensive care unit(NICU). Methods : From January to August, 2004 a nosocomial outbreak of S. marcescens occurred in our NICU. We describe the clinical characteristics of the outbreak and analyse the risk factors for infections with S. marcescens. After the outbreak stopped, 7 isolates from blood were typed using rapid amplified polymorphic DNA analysis(RAPD). Results : S. marcescens was isolated from 24 neonates, 19 infected and 5 colonized. Seven out of nineteen neonates had bacteremia, 4 had ventilator associated pneumonia, 4 had purulent conjunctivitis, 2 had UTI, 1 had meningitis and 1 had a wound infection. Three neonates died due to S. marcescens infection, 2 of 3 had ventilator associated pneumonia, 1 had meningitis complicated with abscess. The mortality rate of S. marcescens infection was 15.8%. Factors associated with S. marcescens infections were previous antibiotic therapy, indwelling catheter and use of ventilators. The isolated strains were resistant to most antibiotics, but frequently sensitive to imipenem, bactrim and amikacin. RAPD typing results show that at least 3 epidemic strains were related with this outbreak. But one genotype was predominant type in this outbreak. The control measures were instituted and the outbreak stopped within 2 months. Conclusion : S. marcescens can cause rapidly spreading outbreaks associated with fatal infections in neonates. If S. marcescens is isolated from clinical specimens, meticulous infection control measures and epidemiologic investigations should be done at an early stage of the outbreak.

• Clinical and Experimental Pediatrics
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• v.49 no.6
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• pp.623-629
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• 2006

Purpose : The mortality rate of neonatal sepsis has been decreased, however, the incidence has not significantly decreased because of increased invasive procedures. This study was designed to make guidelines for choosing antibiotics by analyzing the causative microorganisms and their antibiotics sensitivity test according to the onset of neonatal sepsis. Methods : One hundred seven cases of culture proven sepsis in 89 patients admitted to the NICU of Chonnam University Hospital from Jan. 2000 to Dec. 2004, were enrolled. By reviewing the medical records, clinical data, laboratory findings, causative organisms and their antibiotics sensitivity, and mortality were analyzed. Results : The incidence of neonatal sepsis was 1.7 percent and more prevalent in premature and low birth weight infants. 85.4 percent of neonatal sepsis was late onset. Almost all microorganisms(92.9 percent) were gram-positive in early onset, however, two thirds were gram-positive and one third were gram-negative and Candida in late onset. Gram-negative organisms and Candida were more prevalent in patients who had central line. Gram-positive organisms were sensitive to vancomycin, teicoplanin, and gram-negative were sensitive to imipenem, and cefotaxime. Conclusion : Neonatal sepsis was more prevalent in premature and low birth weight infants. More than 90 percent were gram-positive in early onset, however, one third was gram-negative and Candida in late onset. The first choice of antibiotics were a combination of third generation cephalosporin and clindamycin in early onset, and third generation cephalosporin and glycopeptide in late onset. If there is no response to antibiotics treatment, the use of antifungal agents should be considered.

• Journal of Food Hygiene and Safety
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• v.23 no.1
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• pp.40-50
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• 2008

Spread of pathogenic micro-organisms through contaminated hands is a well recognized way of transmitting disease such as food poisoning. We investigated the prevalence of aerobic plate counts, coliform bacteria, and food-poisoning bacteria on hands in various age groups. The average number of aerobic plate counts was 3.3 log CFU/hand in kindergarteners, 3.4 log CFU/hand in elementary students, 3.2 log CFU/hand in middle school students, 3.4 log CFU/hand in high school students, and 3.3 log CFU/hand in adults. Two kindergarteners, 6 elementary students, and 2 adults were positive for the coliform bacteria. Among the food poisoning bacteria we tested, S. aureus was isolated from 47 individuals. Eight isolates of B cereus were all from kindergarteners. C. perfringens was isolated from 7 individuals. Among 47 isolates of S. aureus, 25 isolates produced toxins. Seven of eight isolates of B. cereus produced toxins. None of seven C. peifringens isolates produced toxins. All 47 isolates of S. aureus were sensitive to ciprofloxacin, trimethoprim/sulfamethoxazole, clindamyccin, imipenem, rifampin and vancomycin. Four isolates (8.5%) were resistant to cefepime, chloramphenicol, cefotetan, and gentamycin. Five isolates (10.6%) were resistant to oxacillin and 6 isolates were resistant to tetracycline. This study shows that it is needs to be established policy of school lunch and personal sanitation management.