PURPOSE: Low-affinity penicillin-binding protein PBP 2a encoded by mecA is closely related to methicillin resistance in staphylococci, and the expression of PBP 2a is controlled by regulator elements encoded by mecR1 and mecI. Deletion or mutation which occurred in mecI is considered to be associated with constitutive production of PBP 2a. We investigated the distribution of mec regulator genes and the presence of the mutations in mecI among mecA gene-positive methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase negative Staphylococcus (MRCNS) strains. METHODS: A total of 28 MRSA and 26 MRCNS clinical strains were isolated at Chung-Ang University Hospital. The distribution of mec regulator genes and the presence of mutations in mecI were analyzed using polymerase chain reaction and direct sequencing. RESULTS: In 28 MRSA and 26 MRCNS, only mecR1A-positive pattern (type lll) was detected in 53.6% of MRSA and 46.4% of MRCNS. The mecR1 (mecR1A and mecR1B) and mecI-positive pattern (type l) were detected in 42.3% of MRSA and 38.5% of MRCNS. In 19.2% of MRCNS was type lV in which no mec regulator genes were detected. Our results showed that a greater genomic variation existed in MRCNS than a MRSA. Results in direct sequencing of mecI revealed that mecI gene tested in our study did not harbour mutations and deletions. There was no correlation between the level of resistance and the presence or absence of mec regulator genes. CONCLUSION: The induction of methicillin resistance and the variability of phenotypic expression of methicillin resistance suggested that additional factors on the chromosome are involved.
Coagulase ; Genes, Regulator* ; Methicillin Resistance* ; Methicillin* ; Methicillin-Resistant Staphylococcus aureus ; Penicillin-Binding Proteins ; Polymerase Chain Reaction ; Staphylococcus*

BACKGROUND: This study compared three non-molecular methods for the detection of methicillin-resistance directly from blood cultures containing Staphylococcus aureus: penicillin-binding protein (PBP) 2a latex agglutination (LA), PBP2a immunochromatographic assay (ICA) and MRSA chromogenic medium (CM). METHODS: Fifty methicillin-resistant S. aureus (MRSA) and 50 methicillin-susceptible S. aureus (MSSA) were seeded into blood-culture bottles. When isolates returned a positive signal, 5 mL of culture was added to serum separator tubes and centrifuged at 1,300 g for 10 min. The pellets were then used as the inoculum for the PBP2a LA, MRSA-CM and PBP2a ICA. The pure colony was used for PBP2a LA test, additionally. RESULTS: The respective sensitivities and specificities were 98 and 100% for PBP2a ICA, and 100 and 100% for MRSA-CM in direct detection of MRSA from positive blood culture. The results of PBP2a LA test using pure colony were entirely compatible with those by mecA gene PCR but the PBP2a LA test using the pellets directly isolated from positive blood culture showed sometimes ambiguous agglutination; its sensitivity and specificity were 78 and 100%, if ambiguous results were scored as negative, and were 90 and 92%, if ambiguous results were scored as positive, respectively. CONCLUSION: For direct detection of MRSA in positive blood culture, MRSA-CM and PBP2a ICA provided excellent results. The PBP2a LA test using pure colony also gave excellent results but the PBP2a LA test by the direct method using pellet of positive blood culture was slightly less sensitive than the other two methods.
Adenosine ; Agglutination ; Immunochromatography ; Latex ; Methicillin Resistance ; Methicillin-Resistant Staphylococcus aureus ; Penicillin-Binding Proteins ; Polymerase Chain Reaction ; Seeds ; Sensitivity and Specificity ; Staphylococcus

BACKGROUND: Traditional antimicrobial susceptibility test methods for detection of methicillin resistant Staphylococcus aureus(MRSA) require 24 hours to perform. In addition, accuracies of these methods can be influenced by prevalence of strains that express heterogeneous resistance. The mechanism of methicillin resistance in S. aureus is based on the production of an additional lowaffinity penicillin binding protein (PBP 2a), which is encoded by mecA gene. Therefore, PCR for mecA gene and immunological methods for PBP 2a could be used to determine resistance, but most clinical laboratories do not have resources to efficiently perform these technique on routine basis. Recently, slide latex agglutination test using latex particles sensitized with a monoclonal antibody against PBP 2a for the direct detection of PBP 2a was developed. In this study, we evaluated this new latex agglutination test, and compared to oxacillin disk diffusion test and PCR detection of mecA gene for detection of MRSA. METHODS: A total 151 clinical isolates of coagulase positive S. aureus were selected. All isolates were subjected to "blinded"testing with oxacillin disk diffusion, PBP 2a latex agglutination, and mecA PCR for detection of MRSA. RESULTS: Of 151 S. aureus, 116 (76.8%) strains were MRSA. The sensitivities and specificities of disk diffusion, latex agglutination and PCR were 94.0 and 91.4%, 97.4 and 100%, 98.3 and 100%, respectively. CONCLUSIONS: PCR for detection of mecA gene and latex agglutination test for PBP 2a are more sensitive and specific methods for detection of MRSA than oxacillin disk diffusion test. Latex agglutination test is rapid, simple, and easier to perform than PCR. In conclusion, PBP 2a detection with latex agglutination test has the potential to be used for routine applications in the microbiology laboratory where mecA gene detection with PCR is not readily available.
Agglutination ; Coagulase ; Diffusion ; Latex ; Latex Fixation Tests ; Methicillin Resistance* ; Methicillin* ; Methicillin-Resistant Staphylococcus aureus ; Microspheres ; Oxacillin ; Penicillin-Binding Proteins ; Polymerase Chain Reaction ; Prevalence ; Staphylococcus aureus* ; Staphylococcus*

Anthracosis ; complications ; Bacterial Proteins ; genetics ; Humans ; Methicillin Resistance ; genetics ; Methicillin-Resistant Staphylococcus aureus ; drug effects ; genetics ; Penicillin-Binding Proteins ; Respiratory Tract Infections ; complications ; microbiology ; Sputum ; microbiology

BACKGROUND: Staphylococcus aureus is a well-known microbe that colonizes or infects the skin in atopic dermatitis (AD). The prevalence of methicillin-resistant S. aureus (MRSA) in AD has recently been increasing. OBJECTIVE: This study aimed to determine the antimicrobial susceptibility patterns in AD skin lesions and evaluate the prevalence of MRSA in Korea. We also recommend proper first-line topical antibiotics for Korean patients with AD. METHODS: We studied S. aureus-positive skin swabs (n=583) from the lesional skin of infants, children, and adults who presented to our outpatient clinic with AD from July 2009 to April 2012. RESULTS: S. aureus exhibited high susceptibility against most antimicrobial agents. However, it exhibited less susceptibility to benzylpenicillin, erythromycin, clindamycin, and fusidic acid. The prevalence of MRSA was 12.9% among 583 S. aureus isolates, and the susceptibility to oxacillin was significantly lower in infants in both acute and chronic AD lesions. CONCLUSION: S. aureus from AD has a high prevalence of MRSA and multidrug resistance, especially in infants. In addition, the rate of fusidic acid resistance is high among all age groups, and mupirocin resistance increases with age group regardless of lesional status. This is the first study comparing the antimicrobial susceptibility rates of S. aureus isolates from AD cases with respect to age and lesion status in Korea.
Adult ; Ambulatory Care Facilities ; Anti-Bacterial Agents ; Anti-Infective Agents ; Child ; Clindamycin ; Colon ; Dermatitis, Atopic* ; Drug Resistance, Multiple ; Erythromycin ; Fusidic Acid ; Humans ; Infant ; Korea* ; Methicillin Resistance* ; Methicillin-Resistant Staphylococcus aureus* ; Mupirocin ; Oxacillin ; Penicillin G ; Prevalence* ; Skin ; Staphylococcus aureus* ; Staphylococcus*

Widespread development of antimicrobial resistance by major bacterial pathogens including Staphylococcus aureus, Streptococcus pneumoniae, Enterococci, and gram-negative bacilli have emerged as a global healthcare concern. Antimicrobial resistance was first identified during the 1940s and 50s with penicillin resistance in S. aureus. During the 1970s and 80s, methicillin-resistant S. aureus (MRSA) rapidly emerged as a major nosocomial pathogen in hospitals throughout the world. In the 1990s, a variation of MRSA emerged as community-associated MRSA (CA-MRSA), which is contracted outside of the hospital setting, and has become one of the most common pathogens associated with skin and skin structure infections in the United States and other parts of the world. Vancomycin-intermediate S. aureus (VISA) was first reported in 1996, and high-level vancomycin-resistant S. aureus (VRSA) was reported in 2002. S. pneumoniae has demonstrated a significant increase in resistance to macrolides and beta-lactam agents since 1980s, particularly in Asian countries while penicillin resistance is not prevalent among non-meningeal isolates according to the new breakpoints from CLSI. Vancomycin resistant enterococci, particularly E. faecium, is a major concern associated with nosocomial infections in many hospitals. Given the widespread emergence and spread of antimicrobial resistant gram-positive cocci during recent decades, the problem is likely to continue to increase as a critical, clinical problem.
Asian Continental Ancestry Group ; Contracts ; Cross Infection ; Delivery of Health Care ; Gram-Positive Cocci ; Humans ; Macrolides ; Methicillin Resistance ; Methicillin-Resistant Staphylococcus aureus ; Penicillin Resistance ; Pneumonia ; Skin ; Staphylococcus aureus ; Streptococcus pneumoniae ; United States ; Vancomycin

BACKGROUND: Coagulase-negative staphylococci (CNS) has been considered as a major causative agent of nosocomial infections. A prompt and accurate detection of methicillin resistance (MR) in staphylococci is a current issue of clinical microbiology laboratories. This study was purposed to evaluate various methods for detecting MR from CNS. METHODS: We selected 78 CNS strains obtained from blood cultures from April 1999 through July 2001 including 20 strains of Staphylococcus epidermidis, 20 S. hominis (SHO), 19 S. capitis, 9 S. haemolyticus, 3 S. saccharolyticus, 1 S. saprophyticus (SAP), 2 S. warneri (SWA), 2 S. xylosus, 1 S. lugdunensis, and 1 S. auricularis. In addition, one SAP strain received from World Health Organization for proficiency tests was also studied. The following methods were compared to the mecA gene PCR: MicroScan PosCombo 12, oxacillin salt agar containing 6 microgram/mL (OSA-6) or 0.6 microgram/mL (OSA- 0.6) of oxacillin, oxacillin disk diffusion (ODD), and MRSA-Screen latex agglutination (LA) for detecting penicillin binding protein 2a. RESULTS: One SWA was failed in mecA-PCR and fifty-nine of 78 (75.6%) CNS were positive for mecA gene. The agreement rates, sensitivities, and specificities for each test were as follows: for MicroScan, 97.3%, 98.2%, 88.9%; for OSA-6 and OSA-0.6 at 24-h incubation, 79.5%, 74.6%, 94.7% and 79.5%, 72.9%, 100%, respectively, and at 48-h incubation, 91.0%, 91.5%, 89.5% and 91.0%, 96.6%, 73.7%, respectively; ODD, 84.6%, 84.7%, 84.2%; LA, 80.8%, 76.3%, 94.7%. One SHO and one SAP that were mecA-negative showed resistance in the MicroScan, ODD, and OSA. CONCLUSIONS: MicroScan appears a reliable method to detect MR in all species of CNS except SHO and SAP. ODD and LA were not appropriate in detecting MRCNS due to a low sensitivity. Although OSA-0.6 at 48-h incubation showed a high sensitivity, the low specificity may limit a routine use in clinical laboratory.
Agar ; Agglutination ; Cross Infection ; Diffusion ; Latex ; Methicillin Resistance ; Oxacillin ; Penicillin-Binding Proteins ; Polymerase Chain Reaction ; Sensitivity and Specificity ; Staphylococcus epidermidis ; World Health Organization

PURPOSE: Infections of methicillin-resistant Staphylococcus aureus (MRSA) are becoming an increasingly concerning clinical problem. The aim of this study was to assess the development of MRSA in urine cultures in a major public university-affiliated hospital and the therapeutical and hygiene-related possibilities for reducing resistance. MATERIALS AND METHODS: This study included 243 samples from patients diagnosed with MRSA infection over a period of 6 years. An agar diffusion test measured the effects of antimicrobial agents against bacteria grown in culture. The analyses were based on the guidelines of the Clinical and Laboratory Standards Institute. RESULTS: A regression analysis was performed, which showed 100% resistance to the following antibiotics throughout the entire testing period: carbapenem, cephalosporin (1st-4th generation), penicillin G, aminopenicillin, beta-lactamase, and isoxazolyl penicillin. However, a significant decrease in resistance was found for amikacin, gentamicin, clindamycin, levofloxacin, erythromycin, and mupirocin. CONCLUSIONS: MRSA showed a decreasing trend of antimicrobial resistance, except against carbapenem, cephalosporin (1st-4th generation), penicillin G, aminopenicillin, beta-lactamase, and isoxazolyl penicillin, for which complete resistance was observed.
Agar ; Amikacin ; Anti-Bacterial Agents ; Anti-Infective Agents ; Bacteria ; beta-Lactamases ; Clindamycin ; Diffusion ; Drug Resistance, Multiple* ; Erythromycin ; Gentamicins ; Humans ; Levofloxacin ; Methicillin-Resistant Staphylococcus aureus* ; Mupirocin ; Penicillin G ; Penicillins

OBJECTIVES: This study investigated the types and antibiotic sensitivity of bacteria in odontogenic abscesses.MATERIALS AND METHODS: Pus specimens from 1,772 patients were collected from affected areas during incision and drainage, and bacterial cultures and antibiotic sensitivity tests were performed. The number of antibiotic-resistant bacteria was analyzed relative to the total number of bacteria that were tested for antibiotic susceptibility.RESULTS: Bacterial cultures from 1,772 patients showed a total of 2,489 bacterial species, 2,101 gram-positive and 388 gram-negative. For penicillin G susceptibility tests, 2 out of 31 Staphylococcus aureus strains tested showed sensitivity and 29 showed resistance. For ampicillin susceptibility tests, all 11 S. aureus strains tested showed resistance. In ampicillin susceptibility tests, 46 out of 50 Klebsiella pneumoniae subsp. pneumoniae strains tested showed resistance.CONCLUSION: When treating odontogenic maxillofacial abscesses, it is appropriate to use antibiotics other than penicillin G and ampicillin as the first-line treatment.
Abscess ; Ampicillin ; Anti-Bacterial Agents ; Bacteria ; Drainage ; Drug Resistance, Microbial ; Humans ; Klebsiella pneumoniae ; Penicillin G ; Pneumonia ; Staphylococcus aureus ; Suppuration

No abstract available.
Penicillin Resistance* ; Penicillins* ; Streptococcus pneumoniae* ; Streptococcus*