PCR-RFLP for Rapid Subtyping of Plasmodium vivax Korean Isolates

Vivax malaria reemerged in Korea in 1993 and the outbreak has been continued with fluctuating numbers of annual indigenous cases. Understanding the nature of the genetic population of Plasmodium vivax circulating in Korea is beneficial for the knowledge of the nationwide parasite heterogeneity and in the implementation of malaria control programs in the country. Previously, we analyzed polymorphic nature of merozoite surface protein-1 (MSP-1) and MSP-3α in Korean P. vivax population and identified the Korean P. vivax population has been diversifying rapidly, with the appearance of parasites with new genetic subtypes, despite the recent reduction of the disease incidence. In the present study, we developed simple PCR-RFLP methods for rapid subtyping of MSP-1 and MSP-3α of Korean P. vivax isolates. These PCR-RFLP methods were able to easily distinguish each subtype of Korean P. vivax MSP-1 and MSP-3α with high accuracy. The PCR-RFLP subtyping methods developed here would be easily applied to massive epidemiological studies for molecular surveillance to understand genetic population of P. vivax and to supervise the genetic variation of the parasite circulating in Korea.

Establishing the heparin therapeutic range using aPTT and anti-Xa measurements for monitoring unfractionated heparin therapy

BACKGROUND: Unfractionated heparin (UFH) has unstable pharmacokinetics and requires close monitoring. The activated partial thromboplastin time (aPTT) test has been used to monitor UFH therapy for decades in Korea, but its results can be affected by numerous variables. We established an aPTT heparin therapeutic range (HTR) corresponding to therapeutic anti-Xa levels for continuous intravenous UFH administration, and used appropriate monitoring to determine if an adequate dose of UFH was applied. METHODS: A total of 134 ex vivo samples were obtained from 71 patients with a variety of thromboembolisms. All patients received intravenous UFH therapy and were enrolled from June to September 2015 at Gyeongsang National University Hospital. All laboratory protocols were in accordance with the Clinical and Laboratory Standards Institute guidelines and the College of American Pathologist requirements for aPTT HTR. RESULTS: An aPTT range of 87.1 sec to 128.7 sec corresponded to anti-Xa levels of 0.3 IU/mL to 0.7 IU/mL for HTR under our laboratory conditions. Based on their anti-Xa levels, blood specimen distribution were as follows: less than 0.3 IU/mL, 65.7%; 0.3–0.7 IU/mL (therapeutic range), 33.6%; and more than 0.7 IU/mL, 0.7%. No evidence of recurring thromboembolism was observed. CONCLUSION: Using the conventional aPTT target range may lead to inappropriate dosing of UFH. Transitioning from the aPTT test to the anti-Xa assay is required to avoid the laborious validation of the aPTT HTR test, even though the anti-Xa assay is more expensive.

Comprehensive Analysis of Blood Cultures Using BacT/Alert 3D FA Plus and FN Plus Media

BACKGROUND: We prospectively evaluated the performance of blood culture resin media, FA Plus and FN Plus, of the BacT/Alert 3D System (bioMérieux Inc., USA) in a tertiary university-affiliated hospital. METHODS: We obtained 2,994 blood culture sets. The positivity and time to detection (TTD) were compared between FA Plus and FN Plus for clinically significant microorganisms. We then categorized patients into two groups based on antibiotic treatment before blood culture to observe the difference of positivity between two groups. RESULTS: Among 2,994 sets received, 371 (12.4%) yielded 385 clinically significant pathogens. Comparing FA Plus to FN Plus media, lactose non-fermenters (18 vs. 1; P0.05). CONCLUSIONS: Complementary detection of microorganisms was observed between FA Plus and FN Plus. Gram-positive cocci including S. aureus grew faster in FA Plus. In addition, the rate of positivity was not affected by prior antibiotic therapy in BacT/Alert 3D resin media.

Epidemiological Study of Erythromycin-Resistant Streptococcus pyogenes From Korea and Japan by emm Genotyping and Multilocus Sequence Typing

BACKGROUND: We determined the epidemiological characteristics of erythromycin (EM)-resistant Streptococcus pyogenes (group A streptococci, GAS) strains isolated from Korea and Japan, using emm genotyping and multilocus sequence typing (MLST). METHODS: Clinical isolates of GAS had been collected from 1992 to 2012 in Korea and from 2004 to 2009 in Japan. EM resistance was determined by the microdilution method, and resistance genotypes were assessed by PCR. The emm genotyping and MLST were performed by DNA sequencing. RESULTS: The emm genotypes and sequence types (STs) were concordant in 143 (85.1%) of 168 EM-resistant GAS strains from Korea. ST36/emm12 (35.1%), ST52/emm28 (22.6%), and ST49/emm75 (16.1%) were the most common types. Most of the ST36 (93.9%) and ST52 (95.8%) strains harbored erm(B), whereas strains ST49, ST42, and ST15 contained mef(A). The concordance between emm genotypes and STs was 41 (93.2%) among 44 EM-resistant GAS strains from Japan. ST36/emm12 (34.1%), ST49/emm75 (18.2%), and ST28/emm1 (15.9%) were the major types. ST36 isolates harbored either erm(B) (56.3%) or mef(A) (37.5%), whereas isolates ST28, ST49, and ST38 carried only mef(A). The proportion of erm(B) and mef(A) was 66.1% and 33.3% in Korea and 22.7% and 68.2% in Japan, respectively. CONCLUSIONS: The common STs in Korea and Japan were ST36 and ST49, whereas ST52 was present only in Korea and ST28 only in Japan. Genotype erm(B) was predominant in Korea, whereas mef(A) was frequent in Japan. There were differences between Korea and Japan regarding the frequencies of emm genotypes, STs, and EM resistance genes among the EM-resistant GAS.

Pappenheimer Bodies in a Splenectomized Patient with Alcohol Abuse

No abstract available.

Favorable Vocal Fold Wound Healing Induced by Platelet-Rich Plasma Injection

OBJECTIVES: To introduce a new injection material for vocal fold diseases, which could be readily translated to clinical practice, we investigated the effectiveness of platelet-rich plasma (PRP) injection on the injured vocal fold in terms of histological recovery. METHODS: Blood samples were drawn from New Zealand White rabbits and PRP was isolated through centrifugation and separation of the samples. Using a CO2 laser, we made a linear wound in the 24 vocal fold sides of 12 rabbits and injected each wound with PRP on one vocal fold side and normal saline (NS) on the other. Morphologic analyses were conducted at 2, 4, and 12 weeks after injection, and inflammatory response, collagen deposit, and changes in growth factors were assessed using H&E and masson trichrome (MT) staining and western blot assay. RESULTS: PRP was prepared in approximately 40 minutes. The mean platelet concentration was 1,315,000 platelets/mm3. In morphological analyses, decreased granulation was observed in the PRP-injected vocal folds (P<0.05). However, the irregular surface and atrophic change were not difference. Histological findings revealed significant inflammation and collagen deposition in NS-injected vocal folds, whereas the PRP-injected vocal folds exhibited less (P<0.05). However, the inflammatory reaction and fibrosis were not difference. In western blot assay, increased amounts of growth factors were observed in PRP-injected vocal folds. CONCLUSION: Injection of injured rabbit vocal folds with PRP led to improved wound healing and fewer signs of scarring as demonstrated by decreased inflammation and collagen deposition. The increased vocal fold regeneration may be due to the growth factors associated with PRP.

Effects of Preincubating Blood Culture Bottles at 37degrees C during the Night Shift and of Collected Blood Volume on Time to Detection and Days to Final Report / 대한임상미생물학회지

BACKGROUND: By varying the collected blood volume and storage temperature of the blood culture bottles prior to entry in an automated blood culture system, growth of organisms will be affected. METHODS: Blood culture bottles with a 20 mL blood volume per set were stored at 37degrees C (1st period) and room temperature (RT, 2nd period) upon arrival at the laboratory after working hours compared to baseline period (10 mL, RT). The time to detection (TTD) for all strains and the number of days until the final report after bottle entry were compared among the three periods. RESULTS: The median TTD for all strains was 13.5 h, 10.6 h, and 11.3 h in the baseline (N=268), 1st (N=454), and 2nd period (N=370), respectively (P<0.001). The final identification report was available within two days of bottle entry for 12.3%, 30.6% and 15.1% of bottles in the three different periods, respectively (P<0.001). CONCLUSION: Collecting an adequate blood volume is critical to reduce TTD. The preincubation of blood culture bottles at 37degrees C during the night shift might enable earlier final reports than storage at RT for samples with the same collected blood volume.

Growth Dynamics of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa as a Function of Time to Detection in BacT/Alert 3D Blood Culture Bottles with Various Preincubation Conditions

BACKGROUND: Delayed entry of blood culture bottles is inevitable when microbiological laboratories do not operate for 24 hr. There are few studies reported for prestorage of these bottles. The growth dynamics of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa were investigated with respect to various preincubation conditions. METHODS: Fifteen or 150 colony-forming units (CFU) of bacteria were inoculated into standard aerobic or anaerobic blood culture bottles. Bottles were preincubated at 25degrees C or 37degrees C for 0, 2, 4, 8, 12, 24, or 48 hr. The time to detection (TTD) then was monitored using the BacT/Alert 3D system (bioMerieux Inc., USA). RESULTS: Significant difference in TTD was observed following preincubation for 8 hr at 25degrees C vs. 4 hr at 37degrees C for S. aureus, 4 hr at 25degrees C vs. 4 hr at 37degrees C for E. coli, 12 hr at 25degrees C vs. 4 hr at 37degrees C for P. aeruginosa, compared to no preincubation (P<0.005). TTD values did not vary significantly with bacterial CFU or with aerobic or anaerobic bottle type. The BacT/Alert 3D system returned false negatives following preincubation of P. aeruginosa for 48 hr at 25degrees C or 24 hr at 37degrees C. CONCLUSIONS: TTD was mainly affected by preincubation temperature and duration rather than by input CFU quantity or bottle type for the 3 experimental bacteria.

A Multicentre Study about Pattern and Organisms Isolated in Follow-up Blood Cultures / 대한임상미생물학회지

BACKGROUND: This study analysed patterns of requests for repeated blood cultures and the microorganisms isolated in follow-up cultures. METHODS: The frequencies and intervals of repeated blood cultures performed during January and February of 2010 at seven university-affiliated hospitals in Korea were evaluated. Results of microbiological cultures at follow-up were analysed with respect to pathogen replication, immune clearance, appearance of new pathogens, and skin contaminants. RESULTS: Among 3,072 patients who received repeated blood cultures, the average number of requests was 3.2. Of the 5,241 follow-up blood culture events recorded, durations of 1, 2, and 3 days between cultures were identified for 23.1%, 21.4%, and 15.0% of events, respectively. Relative to each initial culture, persistent pathogen growth in subsequent culture(s) accounted for 2.3% of events, whereas immune clearance was confirmed in 8.5% of events. Previously undetected pathogens were isolated in 5.2% of the follow-up cultures, the majority of which grew after an interval of six days. Skin contaminants were detected in 7.6% of the repeated cultures, and 76.1% of the follow-ups displayed no growth of microorganisms. CONCLUSION: The most common numbers of repeat culture requests were two and three, and these were typically performed within three days of the initial culture. Among the follow-up cultures, new pathogens were identified in 5.2%, and the majority of this group likely presented for follow-up during a new disease episode.

Effect of Sodium Citrate on Growth of Bacteria in Blood Culture / 대한임상미생물학회지

BACKGROUND: This study compared the growth of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Streptococcus pneumoniae, and Haemophilus influenzae in blood culture bottles containing anticoagulants, sodium polyanethol sulfonate (SPS) and sodium citrate. METHODS: One hundred and fifty colony forming units of five different bacterial species were inoculated into standard aerobic (SA) and standard anaerobic (SN) bottles and were combined with 5 mL of human blood in solution with SPS or sodium citrate. Time to detection (TTD) was then monitored using the BacT/Alert 3D system (bioMerieux Inc.). RESULTS: Compared to the bacteria-only controls, cultures containing S. aureus, E. coli, P. aeruginosa, and S. pneumoniae plus SPS blood or citrated blood trended toward reduced TTD in both SA and SN bottles; however, there was no significant difference in TTD between SPS and sodium citrate anticoagulant. Although H. influenzae showed a remarkable difference in TTD between SPS (SA 14.8 h, SN 15.0 h) and sodium citrate (SA 23.5 h, SN 18.3 h), this difference was not statistically significant (P=0.10). CONCLUSION: Addition of blood enhanced growth of bacteria. All experimental bacteria except H. influenzae showed similar TTD in SPS blood and citrated blood. These results support the usefulness of sodium citrate anticoagulant for artificial inoculation in blood culture bottles.

Inefficiency in 6-Set Requests for Blood Culture Analysis of Cancer Patients with the Central Venous Catheter

BACKGROUND: A central venous catheter (CVC) is commonly used for administering chemotherapy to cancer patients. The institutional guideline of the Gyeongsang National University Hospital (GNUH) for blood culture analysis of indwelling CVC patients recommended 6 sets (2 from the periphery and 4 from each lumen). We analyzed the usefulness of this guideline, because complying with this recommendation requires an abundant amount of the sample and it is both inconvenient and expensive. METHODS: Adult patients (age: > or =18 yr old) who were admitted to the cancer center of GNUH between January 2011 and April 2012 were requested to have their blood culture analysis done. The positive rate, contamination rate, and distribution of microorganisms were compared according to the number of requested sets. The positive results of the stipulated 6 sets were analyzed. RESULTS: A total of 5,263 blood cultures were analyzed during the study period; of them, 74.4% were requests of 2 sets and 20.0% were requests of 6 sets. The positive rates in 2 set requests and 6 set requests were 8.0% and 14.3%, respectively (P<0.001). The requests for 6 sets were repeated about 5 times. All 6 sets showed positive in 16 cases (9.1%), whereas a part of the 6 sets was positive in 18 cases (10.3%). CONCLUSIONS: Although the positive rate was relatively high in the 6 set-requested groups, they had to be repeatedly requested. Microbial growth in a part of the 6-set requests was observed in a very small proportion (10.3%) of the patients, indicating that the benefit of blood culture of 6 sets is very low.

Compliance with Blood Volumes Collected for Blood Cultures between Physicians and Phlebotomists / 대한임상미생물학회지

BACKGROUND: Blood culture is essential for the diagnosis and management of bloodstream infections. Blood volume is a key parameter determining the success of blood cultures. Studies comparing compliance between physicians and phlebotomists regarding optimal blood culture procedure are very rare in Korea. METHODS: After educating physicians (interns) and phlebotomists about the correct procedure for blood culturing, the blood volumes of forty-three percent of randomly selected aerobic and anaerobic culture sets for adult patients (> or =18 years old) were compared between these two groups over a period of three months. Physicians obtained blood from all admitted patients except those in the emergency department, where phlebotomists performed blood collection. RESULTS: The numbers of blood culture sets requested during the study period were 3,238 and 2,136 for the physician and phlebotomist groups, respectively. The blood volumes of blood culture sets were significantly higher for the phlebotomists (16.7 mL) than for the physicians (9.2 mL). The positive rate of blood culture was also higher for the phlebotomist group (10.3% vs. 7.9%). The contamination rates (0.8%) were the same for both groups. CONCLUSION: Although the patients' medical conditions, antibiotics prescriptions, or duration of hospitalization may have affected the positive rate of blood cultures, this rate might also have been influenced by the blood volume. The compliance of phlebotomists was greater than that of physicians regarding the blood volume collected for blood cultures.

Multicenter Study of Molecular Epidemiology and Antibiotic Resistance of Group A Streptococci in 2008-2009 in Korea / 대한임상미생물학회지

BACKGROUND: Group A Streptococcus (GAS) is responsible for a wide spectrum of human diseases. We investigated the distribution of emm types and antibiotic resistance rates of GAS from clinical specimens in several Korean medical centers. METHODS: A total of 192 strains of GAS from throat, blood, and other specimens collected in Seoul, Busan, Ulsan, Iksan, and Jeju were studied in 2008-2009. The emm genotypes were identified using PCR and sequencing. Antimicrobial susceptibility testing was performed by disk diffusion method. Phenotypes of macrolide resistance were evaluated, and macrolide resistance genes were determined by PCR. RESULTS: The emm89 (33.9%) was most frequently detected, followed by emm1 (12.5%), emm12 (8.3%), emm4 (7.8%), and emm75 (7.3%). The distribution of emm types did not show a close relation to the type of specimen and was different for each area. The resistance rates to erythromycin (ERY) and clindamycin (CLI) were 4.6% and 3.7%, respectively. Among the nine ERY-resistant strains, the rate of constitutive resistance was 88.9%, compared with 11.1% for the M phenotype. Five of the ERY-resistant strains were emm28. CONCLUSION: This multicenter study reveals heterogenous emm genotypes by geographic area. Rates of resistance to ERY and CLI were low, and most of the ERY-resistant strains showed a constitutive macrolide-lincosamide-streptogramin B (cMLSB) phenotype.

Investigation of Positive Streptococcus pneumoniae Urinary Antigen Test Results in a Korean University Hospital / 대한임상미생물학회지

BACKGROUND: The Streptococcus pneumoniae urinary antigen test (SPUAT) (Binax Now, USA) was developed for detecting polysaccharide C in urine samples for rapid diagnosis of pneumococcal pneumonia, the most common cause of community-acquired pneumonia (CAP). To validate positive results of these tests, we retrospectively investigated all positive results obtained from the emergency room of a Korean university hospital among patients with suspected CAP. METHODS: One hundred twenty-three positive SPUAT results were abstracted and analyzed from the authors' laboratory information system among the SPUAT results performed from 1,143 pneumonic patients admitted from the emergency room of a university hospital between 2007 and 2008. Medical records, including conventional microbiologic analysis results, were reviewed in detail for all positive test results. RESULTS: Among 123 patients with the positive SPUAT results, 24 patients were excluded due to hospitalization history during the preceding month. Nine of 99 patients (9.1%) with suspected CAP had confirmed pneumococcal pneumonia upon conventional sputum or blood culture. Thirty-five positive results (35.4%) showed other microorganisms upon conventional methods, which might be due to possible cross-reactivity. Among those, 23 positive results were considered bacterial pneumonic agents, and 12 positive results were regarded as urinary tract infection strains or contaminating agents. Fifty-five positive SPUAT results (55.6%) showed negative conventional microbiologic growth, and some positive SPUAT results might be caused by true pneumococcal infection although without cultural evidence. CONCLUSION: Our retrospective study demonstrated that a positive SPUAT result typically does not agree well with conventional culture methods, suggesting that the value of a positive SPUAT result in etiology determination may be limited under practical conditions in a university hospital.

T Types, emm Genotypes and Antibiotic Resistance of Streptococcus pyogenes Isolated fromSchool Children in Jinju, 2006 / 대한임상미생물학회지

BACKGROUND: Streptococcus pyogenes is the most common cause of bacterial pharyngitis. T antigens and emm genotypes are essential markers for an epidemiological study of S. pyogenes. Macrolide resistance of S. pyogenes is a serious obstracle to successfully treating a sore throat. METHODS: One-hundred forty-seven strains of S. pyogenes isolated from healthy school children in 2006 were subjected to T typing and emm genotyping. A disk diffusion method was applied for several antibiotics. A double disk diffusion test was performed to evaluate the phenotype distribution of macrolide resistance. RESULTS: Among T antigens and emm genotypes, T11 (19.7%) and emm78 (16.7%), respectively, were the most common in 2006. Both T5/27/44 (2.3%) and emm44/61 (9.1%) declined to a great extent from about 29% in 2004. The rate of resistance to antibiotics were 11.6% to erythromycin, 4.8% to clindamycin, 21.8% to tetracycline, and 7.5% to ofloxacin. M and cMLSB phenotypes were 52.9% and 41.2% respectively. CONCLUSION: T typing and emm genotyping proved a dynamic change in their distribution in 2006 compared to the results of 2004. Erythromycin and clindamycin resistance remained low as in 2004, whereas ofloxacin resistance increased slightly. M and cMLSB phenotypes were equivalent in 2006, whereas cMLSB was predominant in 2004.

Microbiological Characteristics of Throat Cultures from School Children in Jinju, 2006 / 대한임상미생물학회지

BACKGROUND: Group A streptococci (GAS) are the most common cause of pharyngitis in children. The streptococci in throat cultures from healthy elementary school children in Jinju were compared with previous results. METHODS: Throat cultures were taken from 1,402 healthy school children in 2006. beta-hemolytic streptococci (BHS) were identified with a bacitracin disk (0.04 U) and latex agglutination test (Seroiden Strepto Kit, Eiken, Tokyo, Japan). RESULTS: Two-hundred sixteen (15.4%) and 149 (10.6%) cultures grew BHS and GAS, respectively. The isolation rate of GAS was significantly lower than in 2004 (16.0%) or 2002 (16.9%) (P<0.05). Among BHS, the prevalence of group A strains (69.0%) decreased significantly compared with 2004 (84.9%) and 2002 (83.8%) (P<0.05). None of the 1st-grade children yielded BHS or GAS. CONCLUSION: The isolation rates of BHS and GAS from healthy school children were lower in 2006 than in previous years. Natural immunization against the common serotypes or improvement in individual hygiene might have played roles in the reduction of isolations of GAS.

Survey of Antimicrobial Resistance of Pharyngeal alpha-Hemolytic Streptococci among School Children / 대한임상미생물학회지

alpha-hemolytic streptococci (AHS) are common normal oropharyngeal flora that can transfer antibiotic-resistance genes to Streptococcus pneumoniae. Reports on antibiotic resistance in AHS from throats are rare in Korea. A total of 333 healthy school children were subjected to recovery of AHS from the throat, and antibiotic susceptibility tests were screened with the disk diffusion method. The rate of resistance to erythromycin was 22.2%, to clindamycin 12.0%, and to cefotaxime 3.0%. Whereas the resistance rate of S. pneumoniae to erythromycin exceeds 70% in Korea, pharyngeal AHS showed low resistance rates.

Evaluation of SD Bioline Strep A for Rapid Antigen Testing in Elementary Schoolchildren / 대한임상미생물학회지

BACKGROUND: Rapid antigen tests (RAT) of group A streptococci (GAS) are easy to perform and can save two days of bacterial culture time. Performance of SD Bioline Strep A was analyzed in comparison with throat culture. METHODS: Three consecutive throat swabs were taken from 308 healthy elementary schoolchildren. The first two swabs were tested for SD Bioline Strep A and Quidel Quick Vue Dipstick Strep A rapid antigen tests, and the third one was inoculated onto blood agar plate to grow GAS. RESULTS: Sensitivity, specificity, positive predictive value and negative predictive value of SD Bioline Strep A were 79.3%, 88.9%, 72.2%, and 92.2% respectively. Those of Quidel Quick Vue Strep A were 58.5%, 93.8%, 77.4%, and 86.2% respectively. CONCLUSION: SD Bioline Strep A showed a significantly higher sensitivity and a slightly lower specificity compared to Quidel Quick Vue Strep A. SD Bioline Strep A RAT should be useful for the rapid diagnosis of bacterial pharyngitis and the optimum use of antibiotics.

Association of T Antigens with emm Genotypes of Group A Streptococci / 대한임상미생물학회지

BACKGROUND: T typing has been used as a screening test for epidemiologic studies of group A streptococci (GAS) infections or carriers, and M typing has been performed for virulence studies. However, M typing is difficult to perform in routine laboratories. Recently, genotyping of the emm gene, which encodes the M protein, has become available. We investigated which T antigen is closely associated with a certain emmgenotype. METHODS: GAS were collected from the children in Jinju who were asymptomatic carriers (N=349) or had acute pharyngitis (N=122) during the 3 year-period from 2002 through 2004. T typing was performed by a slide aggulutination, and emmgenotyping by PCR and DNA sequencing. RESULTS: More than 90% of T1, T3, T6, T12, T25, and T5/27/44 antigens were associated with emm1, emm3, emm6, emm12 and 22, emm75, and emm44/61 genotypes, respectively; however, other T antigens, such as T2, T4, T7, T11, and B3264, were not associated with any particular emm genotypes. CONCLUSION: Several T antigens are so closely associated with particular emm genotypes that one could predict emmgenotypes based on the result of T typing.

A Decrease in Erythromycin Resistance Rate of Streptococcus pyogenes in 2004 in Jinju / 대한임상미생물학회지

BACKGROUND: The erythromycin (EM) resistance rates and emm genotypes of Streptococcus pyogenes could vary by geographical location and study period. The purpose of this study, involving a large number of children, was to determine EM resistance rate and its resistance mechanism of S. pyogenes, and to compare these results with those of previous studies performed at the same area. METHODS: Throat cultures were taken from 2,351 healthy children of four elementary schools from October through December, 2004 in Jinju. A total of 328 strains of S. pyogenes were isolated. Antimicrobial susceptibility test was performed by the agar dilution method against six antimicrobial agents. The phenotypes of EM resistance were evaluated by the double-disk diffusion test and the frequency of ermB and mefA genes was determined by polymerase chain reaction. RESULTS: Resistance rates of S. pyogenes to EM, clindamycin and tetracycline were 9.8%, 8.8% and 18.3%, respectively. Almost all isolates were susceptible to ofloxacin, levofloxacin and chloramphenicol. Constitutive resistance (CR) was observed in 87.5%, M phenotype in 9.4%, and inducible resistance only in 3.1%. The ermB and mefA genes were present in 90.6% and 9.4% of the isolates, respectively. CONCLUSION: The resistance rate to EM of S. pyogenes was 9.8% in 2004, which was a large drop from the 51% shown in 2002. CR with the ermB gene was predominant, suggesting that most of the EM resistant isolates have a high level of resistance.