• Food Science of Animal Resources
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• v.42 no.2
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• pp.225-239
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• 2022

As commensal colonizers in livestock, there has been little attention on staphylococci, especially non-aureus staphylococci (NAS), contaminating meat production chain. To assess prevalence of staphylococci in retail pork and slaughterhouse carcass samples in Korea, we collected 578 samples from Korean slaughterhouses (n=311) and retail markets (n=267) for isolation of staphylococci and determined antimicrobial resistance phenotypes in all the isolates. The presence of and prevalence of fusB-family genes (fusB, fusC, fusD, and fusF) and mutations in fusA genes were examined in fusidic acid resistant isolates. A total of 47 staphylococcal isolates of 4 different species (Staphylococcus aureus, n=4; S. hyicus, n=1; S. epidermidis, n=10; Mammaliicoccus sciuri, n=32) were isolated. Fusidic acid resistance were confirmed in 9/10 S. epidermidis and all of the 32 M. sciuri (previously S. sciuri) isolates. Acquired fusidic acid resistance genes were detected in all the resistant strains; fusB and fusC in S. epidermidis and fusB/C in M. sciuri. Multi-locus sequence type analysis revealed that ST63 (n=10, 31%) and ST30 (n=8, 25%) genotypes were most prevalent among fusidic acid resistant M. sciuri isolates. In conclusion, the high prevalence of fusB-family genes in S. epidermidis and M. sciuri strains isolated from pork indicated that NAS might act as a reservoir for fusidic acid resistance gene transmissions in pork production chains.

• Food Science of Animal Resources
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• v.43 no.5
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• pp.792-804
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• 2023

Non-aureus staphylococci (NAS), particularly antimicrobial-resistant NAS, have a substantial impact on human and animal health. In the current study, we investigated (1) the species profiles of NAS isolates collected from healthy broilers, farm environments, and farm workers in Korea, (2) the occurrence of antimicrobial-resistant NAS isolates, especially methicillin resistance, and (3) the genetic factors involved in the methicillin and fluoroquinolone resistance. In total, 216 NAS isolates of 16 different species were collected from healthy broilers (n=178), broiler farm environments (n=18), and farm workers (n=20) of 20 different broiler farms. The two most dominant broiler-associated NAS species were Staphylococcus agnetis (23.6%) and Staphylococcus xylosus (22.9%). Six NAS isolates were mecA-positive carrying staphylococcal cassette chromosome mec (SCCmec) II (n=1), SCCmec IV (n=1), SCCmec V (n=2), or nontypeable SCCmec element (n=2). While two mecA-positive Staphylococcus epidermidis isolates from farm workers had SCCmec II and IV, a mecA-positive S. epidermidis isolate from broiler and a Staphylococcus haemolyticus isolate farm environment carried SCCmec V. The occurrence of multidrug resistance was observed in 48.1% (104/216 isolates) of NAS isolates with high resistance rates to β-lactams (>40%) and fusidic acid (59.7%). Fluoroquinolone resistance was confirmed in 59 NAS isolates (27.3%), and diverse mutations in the quinolone resistance determining regions of gyrA, gyrB, parC, and parE were identified. These findings suggest that NAS in broiler farms may have a potential role in the acquisition, amplification, and transmission of antimicrobial resistance.

• The Journal of the Korean Society for Microbiology
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• v.22 no.4
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• pp.445-451
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• 1987

Coagglutination method is widely used for the diagnosis of Salmonella infection. This test, however, has a disadvantage of false positive reaction due to the coagglutination of staphylococci with non-specific immune complexes or anti-staphylococci antibody in serum. Salmonell O antigen was detected by enzyme immunoassay with protein A-bearing Staphylococcus aureus as in the solid phase. Horse radish peroxidase was labeled to IgG specific against Salmonella O antigen. This enzyme immunoassay was much more sensitive than conventional coagglutination method without false poitive agglutination. To improve the sensitivity for detection of Salmonella O antigen in samples, we tried to determine the optimal concentration of normal IgG that inhibits non-specific binding of horse radish peroxidase labeled IgG to staphylococci, and to establish the optimal condition of reaction between antigen-antibody complex and staphylococci. Non-specific binding of horse radish peroxidase labeled specific IgG to staphylococci was almost blocked when the enzyme labeled IgG was 500-fold diluted with phosphate buffered saline containing 2mg/ml of normal IgG. When staphylococci coated with antibody to Salmonella O antigen were mixed with antigen-antibody complex and then incubated for 1 hour at room temperature, the minimal detectable concentration of Salmonella O antigen was 1ng/ml. The sensitivity of enzyme immunoassay was 100-fold greater than a conventional coagglutination method. This enzyme immunoassay could be expected as an improved method for detection of other infectious agents.

• Korean Journal of Clinical Laboratory Science
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• v.49 no.4
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• pp.420-426
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• 2017

Methicillin-resistant Staphylococcus (MRS) can be colonized in various body sites and is more frequently isolated in healthcare associated persons. This study aimed to evaluate the contamination rate of MRS in a high school environment, those living with closed life style. Staphylococcus aureus was isolated from only the hands of 2 students among a sample of 28 students, and S. aureus were susceptible to methicillin antibiotics. Coagulase negative Staphylococci (CoNS) were isolated from the hands of 26 students (26/28, 92.9%), and among them, 14 (53.8%) isolates were methicillin-resistant CoNS (MRCoNS). Among the 14 MRCoNS, S. warneri was the most common (8/14, 57%) and susceptible to most $non-{\beta}-lactam$ antibiotics, such as clindamycin, erythromycin, ciprofloxacin, tetracycline, gentamicin, and vancomycin. In a culture of 31 desks, S. aureus was not isolated but CoNS were isolated from 26 desks (26/31, 83.6%), which did not harbor the mecA gene. The other bacteria isolated from the hands and desks were Micrococcus and Bacillus spp. In conclusion, methicillin-resistant S. aureus was not isolated from the hands and desks of high school students. However, the frequency of MRCoNS harboring mecA gene were high in the hands of high school students. Therefore, to prevent and to control the transfer of infection, intensifying preventive education, such as hand washing, and active surveillance systems, such as an investigation of contamination or carrier rate of resistant bacteria are necessary.

• Journal of Microbiology
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• v.45 no.4
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• pp.286-290
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• 2007

The purpose of this study was to investigate the prevalence and genetic mechanisms of erythromycin resistance in staphylococci. A total of 102 erythromycin resistant non-duplicate clinical isolates of staphylococci [78. coagulase negative stapylococci (CNS), 24 Staphylococcus aureus] were collected between October 2003 and August 2004 in Istanbul Faculty of Medicine in Turkey. The majority of the isolates were from blood and urine specimens. Antimicrobial susceptibilities were determined by the agar dilution procedure and the resistance phenotypes by the double disk induction test. A multiplex PCR was performed, using primers specific for erm(A), erm(B), erm(C), and msrA genes.. Among the 78 CNS isolates, 57.8% expressed the $MLS_{B}-constitutive$, 20.6% the $MLS_{B}-inducible$, and 21.6% the $MS_B$ phenotypes. By PCR, 78.2% of these isolates harbored the erm(C) gene, 8.9% erm(A), 6.4% erm(B), and 11.5% msrA genes. In S. aureus, the constitutive $MLS_B$ (58.3 %) was more common than the inducible phenotype (20.8%). erm(A) was detected in 50% and erm(C) in 62.5% of the isolates, while 37.5% contained both erm(A) and erm(C). erm(C)-associated macrolide resistance was the most prevalent in CNS, while ermC) and erm(A, C) was the most prevalent in S. aureus.

• YAKHAK HOEJI
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• v.51 no.2
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• pp.108-114
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• 2007

The predominant Macrolides-Lincosamide-Streptogramin B (MLS$_B$) antibiotics resistance genes in staphylococci are erm(A) and erm(C). There is the phenomenon that the ratio of constitutively MLS$_B$ antibiotics resistance (cMLS) in erm(A) is much higher than in erm(C). Thus, we confirmed that the difference of the mutation ratio between erm(A) and erm(C) makes the phenomenon. We examined 8 staphylococci carrying inducibly expressed (iMLS) erm(A) or erm(C) genes. After overnight incubation in the presence of the non-inducer MLS$_B$ antibiotics, spontaneous mutants constitutively expressed MLS$_B$ resistance were selected. Against our expectation, the mutation ratio of erm(A) was lower than erm(C). Therefore, possibilities of other factors determining the ratio of cMLS phenotype might be concerned. All the mutants showed sequence alterations in translational attenuator and all the alterations seemed to give rise to change the second structure of mRNA to express constitutively. For erm(A), 4 different types of sequence deletions ranging from 72 bp to 122 bp and 3 different types of duplications ranging 24 bp to 93 bp were detected. Also, there were 9 different types of duplications ranging 15bp to 154bp in erm(C).

• Genomics & Informatics
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• v.21 no.3
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• pp.34.1-34.10
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• 2023

Nosocomial infections, commonly referred to as healthcare-associated infections, are illnesses that patients get while hospitalized and are typically either not yet manifest or may develop. One of the most prevalent nosocomial diseases in hospitalized patients is pneumonia, among the leading causes of mortality and morbidity. Viral, bacterial, and fungal pathogens cause pneumonia. More severe introductions commonly included Staphylococcus aureus, which is at the top of bacterial infections, per World Health Organization reports. The staphylococci, S. aureus, strain RMI-014804, mesophile, on-sporulating, and non-motile bacterium, was isolated from the sputum of a pulmonary patient in Pakistan. Many characteristics of S. aureus strain RMI-014804 have been revealed in this paper, with complete genome sequence and annotation. Our findings indicate that the genome is a single circular 2.82 Mbp long genome with 1,962 protein-coding genes, 15 rRNA, 49 tRNA, 62 pseudogenes, and a GC content of 28.76%. As a result of this genome sequencing analysis, researchers will fully understand the genetic and molecular basis of the virulence of the S. aureus bacteria, which could help prevent the spread of nosocomial infections like pneumonia. Genome analysis of this strain was necessary to identify the specific genes and molecular mechanisms that contribute to its pathogenicity, antibiotic resistance, and genetic diversity, allowing for a more in-depth investigation of its pathogenesis to develop new treatments and preventive measures against infections caused by this bacterium.

• Korean Journal of Clinical Laboratory Science
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• v.42 no.2
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• pp.86-91
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• 2010

We evaluated the performance of a novel screening test, PBP2a MRSA rapid kit (Dinona Inc., Iksan, Korea), for methicillin-resistant Staphylococcus aureus (MRSA) based on a immunochromatographic assay. The test is able to detect penicillin-binding protein 2a (PBP2a) using the nasal specimens from health care workers. The nasal specimens were obtained from 69 healthcare workers and were incubated in enrichment broth followed eight hours incubatin in BHI with cefoxitin $4{\mu}g/mL$. These broth were tested by PBP2a Rapid Kit. The enrichment broths were also directly tested for tube coagulase using the conventional identification method. 19 of 22 MRSA showed positive results by PBP2a rapid test and direct coagulase test (the sensitivity for detection of MRSA, 86.36%). While, 8 of 47 non-MRSA showed false positive results for the two tests. All of the 8 non-MRSA which showed false positive were co-colonizing isolates with MRCNS and MSSA. In addition, 46 of 49 methicillin-resistant staphylococci (MRS) showed positive results for PBP2a MRSA rapid kit (the sensitivity for detection of MRS, 93.8%), and all of 20 non-MRS showed negative results (specificity, 100%). The combination of PBP2a MRSA rapid kit and direct coagulase test showed the good sensitivity for detection of MRSA from anterior nares but frequently showed false positive results from the co-colonizing carrier with MRCNS and MSSA.

• Korean Journal of Clinical Laboratory Science
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• v.49 no.4
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• pp.407-412
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• 2017

The aim of this study was to shorten the time required for subculture and bacterial identification and obtain a simple and rapid identification method for new test methods for bloodstream infections. The following results were obtained using a mass spectrometer. In Vitek 2, 208 (81.8%) cases were well-identified and 45 isolates were not identified in blood cultures. Among 208 cases, 146 (57.5%) were Gram positive bacteria and 108 (42.5%) were Gram negative bacteria. In total, 233 were identified to the species level and 21 were identified to the genus level. The identification error was found to be Propionibacterium acnes as Clostridium bifermentans. The accuracy of Enterobacteriaceae, glucose non-fermentative bacilli (GNFB), and staphylococci were 81/83 (97.6%), 12/15 (80.0%), and 72/85 (84.7%), respectively. The concordance rate of Vitek 2 and Vitek MS by the direct method was 81.8% and 45 isolates were not identified. Most of the unidentified bacteria were Gram positive bacteria (N=37). The Gram positive bacteria were streptococci (14), coagulase-negative staphylococci (CNS) (11), enterococci (3), Staphylococcus aureus (2), Micrococcus spp. (2), Bacillus spp. (2) and Actinomyces odontolyticus, Finegoldia magna, and Peptostreptococcus spp. The results reporting time was reduced to 24~72 hours compared to the conventional method. The rate of identification of the aerobic and anaerobic cultures was similar, but the use of an anaerobic culture did not require a dissolution process, which could shorten the sample preparation time. These results suggest that the method of direct identification in blood cultures is very useful for the treatment of patients. In further studies, it might be necessary to further improve the method for identifying streptococci and CNS, which were lacking in accuracy in this study.

• Tuberculosis and Respiratory Diseases
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• v.59 no.4
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• pp.389-396
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• 2005

Background : Central venous catheters(CVCs) area major source of nosocomial infection. Chlorhexidine-silver sulfadiazine coated catheters (CHSS) were developed to reduce the rate of CVC infection. However, the clinical effectiveness of CHSS in comparison wth non-coated catheter (NCC) remains to be evaluated. Methods : From January 2004 to December 2004 in medical intensive care unit (ICU) of Asan Medical Center, CVCs were inserted in 446 cases. We retrospectively analyzed characteristics of patients and catheterization,the catheter-related infection rate and colonization, microbiologic findings, and insertion sites (subclavian, jugular, femoral) according to the type of inserted CVCs (NCC: 187 cases, CHSS: 259 cases). Catheter related infection is defined as catheter related bacteremia and catheter related non-bacteremic sepsis. Results : 1) The mean age of the patients in each group was $62{\pm}16$ years, $63{\pm}15$ years (p=0.42), and sex ratio 94:50, 141:69 (p=0.9) in NCC and CHSS. Duration of ICU admission ($29{\pm}37$, $26{\pm}44$ p=0.42), duration of mechanical ventilation ($17{\pm}22$, $15{\pm}19$ p=0.17), and APACHE III score at the time of CVC insertion ($81{\pm}34$, $82{\pm}37$ p=0.61) were not different between both groups. 2) Mean duration of catheterization was 118 in NCC and 119 in CHSS (p=0.98). Number of catheter-days was 2176 days in NCC and 3035 days in CHSS. Catheter-related infection occurred in 9 (4.8%) cases receiving NCC and 4 cases (1.5%) receiving CHSS. Catheterrelated infection incidence per 1000 catheter-days was 4.1 and 1.3, respectively (p=0.04). CHSS was associated with a significant reduction of infection in jugular catheters regarding to insertion sites (p=0.01). 3) Microorganisms causing infection were Staphylococcus aureus (n=3), Candida (n=3), coagulase-negative Staphylococci (n=2), and Klebsiella (n=1) in NCC, and Candida species (n=2), coagulase-negative Staphylococci (n=2), Proteus (n=1) in CHSS. Conclusion : CHSS has significantly reduced the episodes of infection compared to NCC in jugular catheterization in medical ICU.