• Archives of Pharmacal Research
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• v.21 no.3
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• pp.278-285
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• 1998

The microdilution assay recommended by NCCLS (National Committee for Clinical Laboratory Standards) is one of the standardized methods of antibiotic susceptibility test. This method has been widely used clinically to obtain MIC values of antibiotics on pathogenic microorganisms. It is more convenient, rapid and simple to test many samples than other test methods such as agar diffusion assay and broth macrodilution assay. The screening of antimicrobial agents from microbial extracts is too laborious in its process. Therefore, a number of screening methods having more simple procedure have been developed. In our laboratory, we applied microdilution assay for screening the antimicrobial agents. This assay showed dose-response results and was more sensitive than disc diffusion assay in our system. We tested 200 samples of microbial extracts originated from 100 microbial strains and selected several samples as potential candidates. In this report, we show that the microdilution assay is more convenient method in screeing of antibiotic susceptibility than those previously reported.

• Journal of Veterinary Clinics
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• v.3 no.1
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• pp.243-253
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• 1986

In recent years much attention has been paid to swine respiratory infection caused by Haemophilus(H.) Pleuropneumoniae with rapid expansion of pork industry in Korea. The organism may cause an acute respiratory infection with high morbidity and mortality, or it may also cause chronic persistent infection, resulting in loss of body weight. The present study was performed to observe the etiologic situation of H. Pleuropneumoniae infection by evaluating bacteriological, serological examinations with the lungs and sera collected from slaughtered pigs in Daegu city, respectively. In addition, antibiotic susceptibility test was carried out against the isolated strains of H. Pleuropneumoniae. The results obtained are summarized as follows : 1. Only 10 strains of H. Pleuropneumoniae were isolated from the 120 cases of swine lungs examined, and biological and biochemical characteristics of the isolates were identical with that of standard strains(serovar 1 to 6). 2. Out of 336 swine sera examined, 108(32.1%) were shown to be positive against H. Pleuropneumoniae by latex agglutination test. 3. Antibiotic susceptibility test revealed that 10 isolates of H. Pleuropneumoniae were sensitive to 16 kinds of antibiotic such as ampicillin, benzylpenicillin, piperacillin, cephalothin, cefazolin, cefamandol, cefoperagon, lactomoxycefa, tetracycline, minocycline, chloramphenicol, gentamicin, kanamycin, amikacin, colistin and nalidixic acid, whereas cloxacillin, erythromycin, kitasamycin, lincomycin, oleand-amycin, and bacitracin were resistent.

• Food Science and Biotechnology
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• v.14 no.2
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• pp.216-222
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• 2005

This study was performed to determine the antibiotic susceptibility profiles of Salmonella spp., coliforms, Listeria monocytogenes, Staphylococcus aureus and Vibrio spp. isolated from broiler carcasses, aquacultured flounders, hamburgers, and lettuce, which are foods consumed in large quantities in Korea. Salmonella spp. and L. monocytogenes were isolated only from broiler carcasses and Salmonella spp. had a high multidrug resistance rate of 61.1%. Meanwhile, coliforms and S. aureus were isolated from all four foods tested in this experiment. The multidrug resistance rate of coliforms from broiler carcasses was 50%, and that of Vibrio spp. from flounders was 71.4%. The resistance to tetracycline, streptomycin, ampicillin or carbenicillin was common regardless of the kind of food or isolate.

• Journal of Veterinary Clinics
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• v.14 no.2
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• pp.263-267
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• 1997

Eighty-seven strains of Enterobacteriaceae isolated from feces of wild mammals in Choniu zoo were tested for their biochemical reaction and susceptibility to 19 antibiotics or chemicals by using disc diffusion test and/or Microscan Walkway 40/96. Out of 87 isolates, Enterobacteriaceae (44), Hafinia alvei (9), Citrobacterfreundi (5) and Proteus vulgaris (5) were frequently detected. The detective frequency of Enterobacteriaceae in animals classified by their eating pattern was higher in carnivorous and omnivorous than in herbivorous animal. In antibiotic susceptibility tests most of isolates were susceptible to cefazolinl ceftazidime, aztreoname, trimethoprin/sulfamethoxazole, gentamicin, ciprofloxacin, cofuroximel ceftriaxone, cefotaxime and eftizoximel and moderately susceptible to cephalotin and ticarcillin but resistant to ticarcillin/K and amikacin.

• Pediatric Infection and Vaccine
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• v.27 no.3
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• pp.147-157
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• 2020

Purpose: We investigated the trend of antibiotic susceptibility of Haemophilus influenzae over 5 consecutive years. Methods: We analyzed the antibiotic susceptibility of H. influenzae isolated from children aged <18 years, who were admitted to the Asan Medical Center Children's Hospital from March 2014 to April 2019. Antibiotic susceptibility of H. influenzae was determined by the disk diffusion test according to the European Committee on Antimicrobial Susceptibility Testing guidelines. Results: Excluding duplicates, 69 isolates were obtained over the past 5 years. The median age of the patients was 5 years (range, 2.8-8.6 years). The antibiotic susceptibility patterns were as follows: ampicillin (AMP)-susceptible/amoxicillin-clavulanate (AMC)-susceptible (AS/ACS; n=15 [21.7%]), AMP-resistant/AMC-susceptible (AR/ACS; n=21 [30.4%]), and AMP-resistant/AMC-resistant (AR/ACR; n=33 [47.8%]). The prevalence of isolates with AR/ACR phenotype tended to increase from 42.1% in 2014-2015 to 54.5% in 2018-2019 (P=0.342). Compared to 2014-2015, the resistance rates to cefuroxime and ceftriaxone in 2018-2019 increased from 31.6% to 77.3% and from 0.0% to 59.1%, respectively (P=0.003 and P<0.001, respectively). Conclusions: Over the last 5 years, H. influenzae isolates with AR/ACR phenotype and ceftriaxone resistance were frequently observed at our institute. The incidence of resistance to cefuroxime and ceftriaxone has increased significantly.

• Fisheries and Aquatic Sciences
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• v.21 no.2
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• pp.6.1-6.10
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• 2018

The intention of this study was to identify the bacterial pathogens infecting Oreochromis niloticus (Nile tilapia) and Clarias gariepinus (African catfish), and to establish the antibiotic susceptibility of fish bacteria in Uganda. A total of 288 fish samples from 40 fish farms (ponds, cages, and tanks) and 8 wild water sites were aseptically collected and bacteria isolated from the head kidney, liver, brain and spleen. The isolates were identified by their morphological characteristics, conventional biochemical tests and Analytical Profile Index test kits. Antibiotic susceptibility of selected bacteria was determined by the Kirby-Bauer disc diffusion method. The following well-known fish pathogens were identified at a farm prevalence of; Aeromonas hydrophila (43.8%), Aeromonas sobria (20.8%), Edwardsiella tarda (8.3%), Flavobacterium spp. (4.2%) and Streptococcus spp. (6.3%). Other bacteria with varying significance as fish pathogens were also identified including Plesiomonas shigelloides (25.0%), Chryseobacterium indoligenes (12.5%), Pseudomonas fluorescens (10.4%), Pseudomonas aeruginosa (4.2%), Pseudomonas stutzeri (2.1%), Vibrio cholerae (10.4%), Proteus spp. (6.3%), Citrobacter spp. (4.2%), Klebsiella spp. (4.2%) Serratia marcescens (4.2%), Burkholderia cepacia (2.1%), Comamonas testosteroni (8.3%) and Ralstonia picketti (2.1%). Aeromonas spp., Edwardsiella tarda and Streptococcus spp. were commonly isolated from diseased fish. Aeromonas spp. (n = 82) and Plesiomonas shigelloides (n = 73) were evaluated for antibiotic susceptibility. All isolates tested were susceptible to at-least ten (10) of the fourteen antibiotics evaluated. High levels of resistance were however expressed by all isolates to penicillin, oxacillin and ampicillin. This observed resistance is most probably intrinsic to those bacteria, suggesting minimal levels of acquired antibiotic resistance in fish bacteria from the study area. To our knowledge, this is the first study to establish the occurrence of several bacteria species infecting fish; and to determine antibiotic susceptibility of fish bacteria in Uganda. The current study provides baseline information for future reference and fish disease management in the country.

• The Journal of the Korean Society for Microbiology
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• v.22 no.2
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• pp.155-162
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• 1987

To determine the prevalence of antibiotic resistance in fecal E. coli and to investigate possible associations between antibiotic resistance and other plasmid-mediated virulence properties, antibiotic disk susceptibility tests for nine antibiotics were done on 141 strains of E. coli isolated from diarrheal children and well controls. Eighty two percent of the test strains were resistant to one or more antibiotics. Antibiotics to which the test strains were most resistant in descending order were ampicillin (85%), trimethoprim/sulfamethoxazol (60%), and cephalothin (55%). Seventy nine percent of these resistant strains were resistant to two or more antibiotics. All 141 test strains were sorted into enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enteroadherent E. coli (EAEC) and non-pathogenic E. coli and the percentages of strains resistant to multiple antibiotics were compared. Among ETEC regardless of its source, multiple drug resistance was more frequent in strains producing heatstable enterotoxin (ST) only than in strains producing only heat-labile enterotoxin (LT) or both. In EAEC, multiple resistance was more frequently associated with strains isolated from diarrheal patients than with those from well controls. The major antibiotic resistance patterns possessed by multiple resistant enteropathogenic strains were $SXT^R$ $AM^R$, $CR^R$, and $SXT^R$ $AM^R$ $CR^R$. Of 28 ST- producing $SXT^R$ ETEC, 26(96%) were also resistant to ampicillin and 17 (61%) were resistant to cephalothin. The similar pattern was observed in EAEC and EPEC as well. This study has important implications for the treatment of E. coli diarrhea with antibiotics because it is possible that dissemination of virulence could occur under the force of selective antibiotic pressure. In addition, this study suggests that the in vivo efficacy of SXT in treating diarrheal illness be reevaluated.

• Journal of Veterinary Clinics
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• v.22 no.2
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• pp.114-118
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• 2005

Bacterial disease caused by Aeromonas are among the most common and troublesome diseases of fish raised in aquaculture systems. In this study, some strains identified as belonging to the Aeromonas were isolated from neon tetra (Hyphessobrycon herbertaxelrodi) skin and fin, as well as from water samples. VITEK system and API ZYM examination of the isolated strains were undertaken, and it seemed to correlate with the Aeromonas, proved to be Aeromonas veronii. The antibiotic susceptibility test of isolated strains to different groups of antibiotics was evaluated using the disc diffusion method. Cefixime was the most sensitive antibiotic.

• Journal of Microbiology and Biotechnology
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• v.14 no.3
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• pp.515-519
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• 2004

Listeria spp. were isolated from a total of 402 naturally contaminated domestic ready-to-eat (RTE) vegetable samples by the conventional Food and Drug Administration protocol and confinned by API-Listeria kit. Also, the susceptibility to 12 antibiotics, polymerase chain reaction (PCR) assay for virulence gene of pathogenic Listeria monocytogenes isolates, and in vitro virulence assay using myeloma and hybridoma cells from murine and human sources were tested. Among the samples, 17 samples (4.2％) were found to be contaminated with Listeria species. Among the 17 strains of Listeria spp. isolates, only 2 strains (11.8％) of L. monocytogenes and 15 strains (88.2％) of L. innocua were identified. Antibiotic susceptibility test showed that the Listeria spp. isolates were very susceptible to the antibiotics tested, except for nalidixic acid. Among 17 strains of Listeria spp., PCR analysis showed that 2 strains of L. monocytogenes isolates proved to have a virulence hly gene, but none of L. innocua had the hly gene. Also, hybridoma Ped-2E9 cells assay showed that only L. monocytogenes isolates killed approximately 95-99％ hybridoma cells after 6 h, but L. innocua isolates had about 0-5％ lethal effect. These results indicate that PCR assay with hly primer or hybridoma Ped-2E9 cells assay could be used as a good monitoring tool or in vitro virulence test for L. monocytogenes.

• Journal of Periodontal and Implant Science
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• v.24 no.3
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• pp.561-571
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• 1994

The comparative study on the predominant cultivable periodontopathic bacteria were done 2 weeks after the application of the e-PTFE membrane and collagen membrane in the controlled tissue regeneration procedures. The purpose of the present study also included the antibiotic susceptibility test (ciprofloxacin, tetracycline, clindamycin) of these cultured organisms. 0.1% chlorhexidine mouthwash (10ml twice/day for 6 weeks) and systemic doxycycline (200mg/day for 2 weeks) were administered for supragingival and subgingival plaque control respectively. Four clinical isolates of A.a. from 2 patients were found to be resistant to tetracycline which were susceptible to clindamycin and ciprofloxacin. One isolate of W.r. and two unidcntified microorganisms were resistant only to clindamycin and one isolate of NID BPB and E.c. and two isolates of unidentified microorganisms were resistant only to ciprofloxacin. Overall susceptibility of tested microorganisms to ciprofloxacin, tetracycline and clindamycin were 85%, 77% and 89% respectively. The results indicated no significant differences in the percentage of cultivable periodontopathic bacteria between the two membranes, and also the microorganisms resistant to tetracycline after systemic administration of doxycycline turned out to be susceptible to either ciprofloxacin or clindamycin.