• Korean Journal of Veterinary Service
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• v.47 no.1
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• pp.27-33
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• 2024

At the present study, it was aimed to explore the states of antimicrobial resistant Staphylococcus aureus isolates from 1,360 chickens, pigs and cattle carcass (400 chickens, 480 pigs and 480 cattle) in Daegu province from January 2022 to December 2022. Among 1,360 samples, 81 of S. aureus were isolated cattle (1.4%), pigs (7.7%) and chickens (9.2%). In antimicrobial susceptibility test, all of the isolates were demonstrated susceptibility to rifampin. But the isolates were showed resistance other antibiotics in order of tetracycline (62.9%), ciprofloxacin (62.9%), tobramycin (58.0%), gentamicin (51.8%), amikacin (40.7%), penicillin (39.5%), clindamycin (35.8%), enrofloxacin (33.3%), trimethoprim/sulfamethoxazole (30.8%), oxacillin (30.8%), minocycline (29.6%), erythromycin (25.9%), quinupristin/dalfopristin (20.9%), chloramphenicol (12.3%), cefoxitin (9.8%). Among the 81 S. aureus isolates, 25 (30.8%) methicillin-resistant staphylococcus aureus (MRSA) were observed. Seven (28.0%) of 25 MRSA harbored mecA gene. About 96% of MRSA were multidrug resistance to at least 3 more drugs. A continuous monitoring and surveillance program to prevent antimicrobial resistance in livestock products is demanded.

• Food Science of Animal Resources
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• v.31 no.1
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• pp.47-53
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• 2011

Salmonella enterica serovar Typhimurium (ST) is one of the most common serovars isolated from humans and animals. It has been suggested that ST infections in Koreans are largely due to the consumption of contaminated pork and beef. To investigate the genotypes, phage types, and antimicrobial resistance patterns for ST isolates of different origins, a total of 70 ST strains, including 19 isolates from humans, 44 isolates from pigs, and 6 isolates from cattle, were analyzed using pulsedfield gel electrophoresis (PFGE), phage typing, and antimicrobial susceptibility tests. Forty-three distinct PFGE patterns were generated from 70 ST isolates, which were grouped into 14 PFGE groups (from A to N) at the level of 75% similarity. The most prevalent group was the A (A1-A17 subtypes) group, encompassing 54.5% (38/70) of ST isolates. ST isolates from pigs and cattle mostly belong to groups A and L, whereas ST isolates from humans mostly belong to groups F and C. Antimicrobial susceptibility tests using 11 antimicrobial agents showed that resistance to tetracycline (TE) (81.4%) was highly prevalent, followed by streptomycin (S) (64.3%) and nalidixic acid (NA) (31.4%) resistance. A total of seventeen antimicrobial resistance patterns were observed. Only 8.6% of isolates, including a reference strain, were susceptible to all antimicrobial agents tested. The most prevalent resistance pattern was TE-S (37.1%), which was seen in 66.6% of bovine, 40.8% of swine and 21.1% of human isolates. Three ST isolates from humans (15.9%) showed resistance to 7-8 antimicrobials. The most predominant phage type (PT) was U302 (64.3%), followed by DT170 (10.0%). PFGE types did not coincide with antimicrobial resistance patterns and phage types; therefore, the combination of those types allowed for further differentiation between tested ST isolates.

• Korean Journal of Clinical Laboratory Science
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• v.45 no.1
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• pp.21-25
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• 2013

Acinetobacter baumannii is an aerobic, gram-negative and glucose-non-fermenting bacterium, which has emerged as a serious opportunistic pathogen. Many clinical microbiology laboratories use the Vitek 2 system for the routine antimicrobial susceptibility testing process, including testing on A. baumannii isolates. However, in case of amikacin, it is now recommended to perform additional antimicrobial susceptibility testing for A. baumannii strains due to the relatively lower minimum inhibitory concentration (MIC) in the Vitek 2 system compared to conventional reference methods. In our study, we assessed MIC for amikacin susceptibility testing of A. baumannii isolates in the Vitek 2 system, the agar dilution, Etest, and disk diffusion method. We collected 40 gentamicin-resistant, A. baumannii strains (amikacin MIC by Vitek 2:${\leq}2{\mu}g/mL$, 2 isolates; $4{\mu}g/mL$, 34 isolates; $8{\mu}g/mL$, 4 isolates) from a University hospital and compared the Vitek 2 system to other reference methods for testing susceptibility to amikacin. The Vitek 2 system showed major errors in all of the 40 isolates, yielding a low MIC. The results of our study strongly suggested that the Vitek 2 system was not a reliable method to test the MICs of gentamicin; ranging from ${\geq}16{\mu}g/mL$ for amikacin susceptibility. Other tests, such as agar dilution, Etest, or disk diffusion methods, should be paralleled to determine the MIC of amikacin in A. baumannii.

• Journal of Veterinary Clinics
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• v.38 no.5
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• pp.225-230
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• 2021

A 4-year-old gelding Thoroughbred racehorse, which had been undergoing antibiotic therapy at a local veterinary clinic, was referred to the KRA veterinary center with a 20-day history of continuous right nasal discharge. Patient's history, endoscopic examination, and radiographic examination revealed primary maxillary sinusitis. Under sedation, surgical intervention was performed to collect samples and remove the accumulated mucopurulent exudate in the sinus. Swab samples were collected from the sinus during surgery for cytology and antimicrobial susceptibility testing. Only one type of bacteria was cultured, and molecular analyses of 16S ribosomal RNA gene sequences identified it as Staphylococcus aureus (S. aureus). The isolate was resistant to multiple antibiotics, which are frequently used in equine practice. Trimethoprim-sulfamethoxazole was chosen based on antibiotic susceptibility test, trephination, and sinus lavage using saline were applied to treat bacterial sinusitis. The clinical signs improved after 1 month and the patient resumed training. This report describes S. aureus isolated from bacterial maxillary sinusitis in a horse and its antibiotic susceptibility.

• Restorative Dentistry and Endodontics
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• v.9 no.1
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• pp.89-99
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• 1983

The rational approach to antimicrobial therapy of infected root canals is based on accurate identification of the infecting organism and on the organism's susceptibility to antimicrobial agents as measured by standardized techniques. In establishing criteria for the selection of antibiotics, a susceptibility test should be performed. The purpose of this study was to investigate the susceptibility of 224 aerobic and anaerobic microbial strains isolated from infected root canals to various antibiotics. This was performed by using 7 antibiotic sensi-disc: Penicillin (10 units), Ampicillin (10 mcg), Tetracycline (30 mcg), Streptomycin (10 mcg), Kanamycin (30 mcg), Lincomycin (2 mcg), and Clindamycin (2 mcg). The results were as follows; 1. Strains isolated from infected root canals was shown to be most susceptible to Clindamycin, while Streptomycin exhibited least antibacterial properties. 2. Anaerobes were found to be susceptible to Penicillin, Ampicillin, and Clindamycin. 3. Streptomycin and Kanamycin were shown to be effective against Staphylococcus aureus and Staphylococcus epidermis, however, unidentified G(+) cocci organisms were found to be resistant to these agents. 4. Bifidobacterium sp. was susceptible to Lincomycin while G(+) rods were resistant to it. 5. Staphylococcus aureus, Micrococcus sp., and anaerobes were highly susceptible to Clindamycin. 6. All of the antibiotics tested were shown to be very effective against Eubacterium sp.

• Korean Journal of Microbiology
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• v.47 no.4
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• pp.381-385
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• 2011

Methicillin-resistant Staphylococcus aureus (MRSA) is one of major pathogen causing hospital infection and several diseases such as purulent infection, bacteremia. The isolation ratio of MRSA is gradually increased up to 80% in the hospital, which makes a limitation for treatment of antibiotics because the isolated MRSA show resistance to methicillin as well as other antibiotics. This study proposes that mecA detecting methods which are not commonly used because of cost in the hospital is a more accurate method than Susceptibility Testing to detect a MRSA. We compared Staphylococcus aureus ATCC 29213 as a negative control and 20 MRSA strains isolated from patients by these two methods. We amplified mecA gene by polymerase chain reaction (PCR) and confirmed the PCR products by sequencing. All of the MRSA showed oxacillin and cefoxitin resistance whereas 85% (16/19) of the strains had mecA wildtype. These results suggest that some of the MRSA are mecA mutants therefore mecA genotyping reinforces the MRSA detection by antibiotic susceptibility test.

• Korean Journal of Veterinary Research
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• v.44 no.3
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• pp.427-432
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• 2004

The objective of this study was to determine the prevalence of pneumonic bacteria in lungs and nasal swabs of cattle with respiratory diseases. From 95 pneumonic lungs of slaughtered cattle, 41 (43.2%) positive lungs were yielded with 54 pneumonic bacteria, which corresponded to P. multocida (n = 34), A. pyogenes (n = 14) and P. haemolytica (n = 6). One-hundred sixty seven pneumonic bacteria were isolated from 195 nasal swabs in calves, 64.7% (108 isolates) belonged to P. multocida, 16.2% to A. pyogenes, 13.8% to P. haemolytica and 5.4% to H. somnus. Fifty percents (n = 6) of isolates from pneumonic lungs of calves were identified as P. multocida. All isolates of P. multocida belonged to type A according to hyaluronidase test. Antimicrobial susceptibility tests showed that most isolates of P. multocida and P. haemolytica were sensitive to amoxicillin/clavulanic acid, cephalothin, ciprofloxacin, enrofloxacin, fluorophenicol and norfloxacin. The emergence of antimicrobial resistant Pasteurella spp. observed in this study, however, might limit such application. According to histopathological examination, pneumonia by mycoplasma or/and bacteria accounted for 92.8% among 69 pneumonic lungs of slaughtered cattle.

• Infection and chemotherapy
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• v.50 no.4
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• pp.328-339
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• 2018

Background: Pneumococcal disease is a major cause of morbidity and mortality worldwide, especially in patients with comorbidities and advanced age. This study evaluated trends in epidemiology of adult pneumococcal disease in Crete, Greece, by identifying serotype distribution and antimicrobial resistance of consecutive Streptococcus pneumoniae strains isolated from adults during an 8-year time period (2009-2016) and the indirect effect of the infant pneumococcal higher-valent conjugate vaccines 10-valent pneumococcal conjugate vaccine (PCV10) and 13-valent pneumococcal conjugate vaccine (PCV13). Materials and Methods: Antimicrobial susceptibility was performed by E-test and serotyping by Quellung reaction. Multidrug resistance (MDR) was defined as non-susceptibility to penicillin (PNSP) combined with resistance to ${\geq}2$ non-${\beta}$-lactam antimicrobials. Results: A total of 135 S. pneumoniae strains were isolated from adults during the study period. Twenty-one serotypes were identified with 17F, 15A, 3, 19A, and 11A, being the most common. The coverage rates of PCV10, and PCV13 were 17.8% and 37.8%, respectively. PCV13 serotypes decreased significantly from 68.4% in 2009 to 8.3% in 2016 (P = 0.002). The most important emerging non-PCV13 serotypes were 17F, 15A, and 11A, with 15A being strongly associated with antimicrobial resistance and MDR. Among all study isolates, penicillin-resistant and MDR strains represented 7.4% and 14.1%, respectively. Predominant PNSP serotypes were 19A (21.7%), 11A (17.4%), and 15A (17.4%). Erythromycin, clindamycin, tetracycline, trimethoprim-sulfamethoxazole, and levofloxacin resistant rates were 30.4%, 15.6%, 16.3%, 16.3%, and 1.5%, respectively. Conclusion: Although pneumococcal disease continues to be a health burden in adults in Crete, our study reveals a herd protection effect of the infant pneumococcal higher-valent conjugate vaccination. Surveillance of changes in serotype distribution and antimicrobial resistance among pneumococcal isolates are necessary to guide optimal prevention and treatment strategies.

• Korean Journal of Veterinary Service
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• v.34 no.4
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• pp.353-359
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• 2011

Fowl cholera is a contagious acute and chronic disease caused by Pasteurella multocida in both domesticated and wild birds. Acute fowl cholera in both chickens and wild birds has recently been documented in Korea, but the chronic form has not been reported in Korea until now. This study describes the first outbreak of chronic fowl cholera in 13-week-old Arbor Acre broiler breeder chickens submitted to the College of Veterinary Medicine, Kyungpook National University in April 2006. The clinical signs of the affected flock of 9,621 chickens were lameness caused by swollen hock joints, diarrhea, ruffled feathers, and an average weekly mortality of 1.0%. At necropsy, purulent or caseous exudates were found in the hock and wing joints, humerus, and eyes, and severe pneumonia and pericarditis were discovered. Eleven bacterial isolates obtained from the liver, joint, infraorbital sinus and sternal bursa of the submitted chickens were all identified as Pasteurella multocida based on their physiological and biochemical characteristics. Five isolates were examined for antimicrobial susceptibility against 21 different antimicrobial agents including ampicillin. All were resistant to kanamycin, neomycin, and streptomycin, and some were resistant to gentamicin. The tested isolates were all susceptible to the other 17 antimicrobial agents. All 11 isolates were capsular serogroup A based on multiplex polymerase chain reaction. In addition, two of five isolates used in the antimicrobial susceptibility test were identified as somatic serotype 1 by an agar gel diffusion precipitin test, while the others were non-typable.

• Journal of Yeungnam Medical Science
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• v.10 no.1
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• pp.28-36
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• 1993

Major pathogenic Gram-negative organisms such as P. aeruginosa, Serratia species, E. coli, Enterobacter species which are isolated from the specimens in large medical centers are greatly resistant to the commonly used antibiotics. Gram-negative bacilli, which had been isolated in Yeungnam University Hospital during the period from December 1992 to April 1993 and turned out to be resistant to the primary antibiotics susceptibility test for chloramphenicol, ampicillin, cephalothin, gentamicin, tetracyclin, amikin and tobramycin, were subjected to the secondary antibiotics susceptibility test for aztreonam, ceftazidime, ciprofioxacine, cefotaxime, cefamandole, piperacillin, ticarcillin and sulfamethoxazole trimethopime. Out of 315 tested organisms, 167 organisms(53%) were resistant to all secondary antibiotics in vitro. Antimicrobial activity of ceftazidime(37.1%), aztreonam(11.%), ciprofioxacine(7.9%) against Gram negative bacilli were slightly more active than other antibiotics tested, while cefamandole was not active to all the Gram-negative bacilli tested. According to the specimens, E. coli was the most frequently resistant organisms to the primary antibiotics from urine, A. baumanii, from respiratory system and wounds, and P. aeruginosa from various specimens. In summary, Gram negative bacilli resistant to the primarily applied antibiotics also were resistant to the secondary antibiotics. Rearrangement of the antibiotics disks for the antibiotic susceptibility test should be considered.