Jayoung Kim, Yeon-Joon Park, Nam Yong Lee, Chulhun L. Chang, Miae Lee, Jong Hee Shin
Ann Clin Microbiol 2013 March, 16(1): 1-7. Published on 20 March 2013.
Background: We analyzed the prevalence of anti-tuberculosis drug resistance in Mycobacterium tuberculosis isolates from respiratory specimens of patients with newly diagnosed and previously treated tuberculosis.
Methods: From February 2010 to July 2010, a total of 542 M. tuberculosis clinical isolates were collected from pulmonary tuberculosis patients in six university hospitals distributed throughout Korea. We analyzed the results of anti-tuberculosis drug resistance tests according to treatment history and geographic location.
Results: Among the 542 isolates, 473 (87.3%) were from newly diagnosed cases and 69 (12.7%) were from previously treated cases. The rates of multi-drug resistance (MDR), fluoroquinolone (ofloxacin, levofloxacin, and moxifloxacin) resistance, and extensive drug resistance (XDR) were 3.8%, 1.1-1.5%, and 0%, respectively, in new cases, and 21.7%, 13.0-17.4%, and 4.3%, respectively, in previously treated cases. In the previously treated cases, the proportions of XDR-TB in MDR-TB were 20% (3/15). The resistance rates were variable according to geographic location.
Conclusion: As the anti-tuberculosis drug resistance rates are much higher in newly diagnosed cases than in previously treated patients, efforts should be made to ensure that tuberculosis treatment is successful. In addition, before the selection of an anti-tuberculosis drug treatment for previously treated patients, the susceptibility test results, including to fluoroquinolone, should be verified.
[in Korean]
Jeong Hwan Shin, Eui Chong Kim, Sunjoo Kim, Eun-Ha Koh, Dong-Hyun Lee, Sun-Hoi Koo, Ji-Hyun Cho, Jae-Seok Kim, Nam Hee Ryoo
Ann Clin Microbiol 2013 March, 16(1): 8-12. Published on 20 March 2013.
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.
Min-su Oh, Jaechun Lee
Ann Clin Microbiol 2013 March, 16(1): 13-18. Published on 20 March 2013.
Background: Pulmonary tuberculosis is an infectious disease of the lungs caused by Mycobacterium tuberculosis complex (MTB) designated by law in Korea, and accurate diagnosis and urgent treatment are necessary for the maintenance of public health. Recently, nontuberculous mycobacteria (NTM) have been more frequently isolated in respiratory system specimens, which were confused with MTB. We investigated whether the incidence of NTM isolation is increasing in Jeju, Korea.
Methods: The results of microbacterial cultures of acid fast bacilli (AFB) from respiratory system specimens were collected at Jeju National University Hospital, Jeju, Korea from 2004 to 2011. The incidences of MTN or NTM isolation were analyzed.
Results: A total of 15,484 AFB cultures were performed in 6,281 patients. In 2004, 365 AFB cultures were requested, and the number increased to 1,550 in 2011. However, the culture-positive rate decreased from 18.7% in 2004 to 6.19% in 2011. Among the 573 cultured specimens, 506 MTB (88.3%, mean age of 49.7, male 63.2%) and 72 NTM (12.6%, mean age of 65.8, male 50.0%) were identified. The proportions of NTM isolations were less than 10% until 2009, but increased to 30% after 2010 (P＜0.001). M. avium complex (MAC) was the most frequently isolated NTM, followed by M. abscessus.
Conclusion: The proportion of NTM isolation is increasing. A clinical diagnosis of pulmonary tuberculosis based on respiratory system specimens should be made with caution, especially in cases of positive AFB smears.
[in Korean]
Seri Jeong, Yoon Jung Kim, Il Kwon Bae, Moon Jung Kim, Seok Hoon Jeong
Ann Clin Microbiol 2013 March, 16(1): 19-24. Published on 20 March 2013.
Background: Cytomegalovirus (CMV) infection is a major cause of morbidity and mortality in immunocompromised patients. We compared the abilities of the recently developed Real-Q Cytomegalovirus Kit (Biosewoom Inc., Korea) and the previously used PANA mPCR CMV Detection Kit (Panagene Inc., Korea) to detect CMV.
Methods: We analyzed 300 samples (whole blood: 262, urine: 37, CSF: 1) submitted for qualitative CMV PCR testing during October 2011 at Yonsei University College of Medicine Severance Hospital. real-time PCR was performed with a Real-Q Cytomegalovirus Kit and conventional PCR was conducted with a PANAmPCR CMV Detection Kit.
Results: The positive rates of both real-time PCR and conventional PCR were 25.3% (76/300), and the kappa coefficient (K) was 0.96 (95% confidence interval (CI), 0.93-1.00). The concordance rate of the Real-Q Cytomegalovirus Kit and the PANAmPCR CMV Detection Kit was 98.7% (296/300), and four out of 300 samples showed discordant results. If the concordant results of 296 samples and the four results confirmed by direct sequencing were assumed to be true, the sensitivity and specificity of the Real-Q Cytomegalovirus Kit were 97.4% (95% CI, 93.8-100.0%) and 99.1% (95% CI, 97.9-100.0%), respectively.
Conclusion: The recently developed Real-Q Cytomegalovirus Kit showed excellent sensitivity and specificity, and had a high concordance rate with the previously established PANAmPCR CMV Detection Kit, which uses conventional PCR. Furthermore, real-time PCR could decrease the test time, as the electrophoresis step required for conventional PCR is not required for real-time PCR.
[in Korean]
HyeonHee Kim, Semi Jeon, JunYoung Kim, SeongHan Kim, Deog-Yong Lee
Ann Clin Microbiol 2013 March, 16(1): 25-32. Published on 20 March 2013.
Background: Cholera is a representative water-borne disease that is caused by V. cholera ctx (+). V. cholera El Tor was previously the primary pathogen, but after the seventh pandemic outbreak, it was replaced by a V. cholera El Tor variant with a classical phenotype and genotype. In this study, we investigated the genotypic and phenotypic characteristics of imported V. cholerae El Tor in Korea.
Methods: Forty-nine V. cholerae O1 El Tor strains isolated from 2004 to 2011 were used in this study. Polymerase chain reaction amplification of the ctxB and rstR genes was used for biotype determination. An antimicrobial susceptibility test was performed for phenotypic analysis, and pulse field gel electrophoresis (PFGE) was used for analysis of genetic relatedness.
Results: Classical ctxB genes were found in all of the isolates, while classical, El Tor, and combined rstR genes were found. Twenty strains showed antimicrobial resistance against streptomycin, sulfamethoxazole/ trimethoprim, nalidixic acid, and ciprofloxacin. Based on PFGE, all isolates were grouped as cluster B. The country of origin and resistance pattern were highly related, although the time of influx and serogroup were not.
Conclusion: Isolates of V. cholera El Tor imported since 2004 were hybrids of V. cholera El Tor, which has the classical ctxB gene and is considered to be a CTX prophage. The SXT element plays an important role in antimicrobial resistance. PFGE patterns, which can be used for analysis of imported V. cholera, revealed the relatedness of the resistant isolates.
[in Korean]
Seungok Lee, Yeon-Joon Park, Hae Kyung Lee, Soo-Young Kim, Ja-Young Kim, So-Young Lee, Jin-Kyung Yoo
Ann Clin Microbiol 2013 March, 16(1): 33-38. Published on 20 March 2013.
Background: We investigated the prevalence of various pathogens (13 enteric bacteria and 5 viruses) which cause diarrhea using multiplex PCR of stool specimens and compared two multiplex PCR methods for detecting diarrheagenic Escherichia coli.
Methods: A total of 405 stool specimens submitted between November 2010 to February 2011 for routine culture of enteric pathogens were included and screened for five viruses (astrovirus, Group A rotavirus, enteric adenovirus, norovirus G1/G2) and eight bacteria (Salmonella spp., Shigella spp., Campylobacter spp., Vibrio spp., C. difficile Toxin B, C. perfringens, Y. enterolytica, Aeromonas spp.) using the SeeplexⓇ Diarrhea ACE detection kit (Seegene). In addition, virulence-associated genes of enteropathogenic E. coli, (EPEC), enterohemorrhagic E. coli (EHEC), enteroinvasive E. coli, (EIEC), enterotoxigenic E. coli (ETEC), and enteroaggressive E. coli (EAEC) were detected using 16-plex PCR and a commercial diarrheagenic E. coli detection (DEC) PCR kit (SSI Diagnostica).
Results: Overall, 138 (34.1%) of 405 samples was positive for pathogen. The positive rate for virus was 18.5%. norovirus G2, Group A rotavirus, enteric adenovirus, astrovirus and norovirus G1 were detected in 40, 23, 8, 3 and 1 samples, respectively. The positive rate for bacteria was 24.4% (99/405). C. difficile toxin B was the most frequently detected, followed by C. perfringens, EPEC, and EAEC. The agreements of the two multiplex PCR methods for detecting EPEC and EHEC were 99.3% and 100%, respectively.
Conclusion: The detection rate was high (34.1%) including various diarrheagenic E. coli (6.2%) and C. perfringens (5.2%). Multiplex PCR is thus useful for detecting various pathogens.
[in Korean]
Jeong Su Park, Sue Shin, Jong Hyun Yoon, Eun Youn Roh, Ju Young Chang, Eui-Chong Kim
Ann Clin Microbiol 2013 March, 16(1): 39-44. Published on 20 March 2013.
Background: Testing for possible microorganism contamination in umbilical cord blood (UCB) is essential for validating the product safety of allogeneic cellular therapeutics. We analyzed the level of contamination and related factors at the largest public cord blood bank in Korea. In addition, we also studied the influence of cryopreservation on contaminating microorganisms.
Methods: UCB was collected, transported, processed, and stored according to standard operating procedures. Microbial detection and identification was performed using a conventional automated blood culture system (BacT/ALERT; bioMérieux, France) with an inoculum of 5-10 mL plasma for pre-freezing UCB. Forty randomly selected non-conforming units were thawed and studied for microbiologic recovery with an inoculum of 2.5 mL.
Results: Among a total of 21,236 UCB, 677 (3.19%) were positive for culture. The most frequently identified organism was Lactobacillus spp. (17.2%), followed by Bacteroides spp. (10.1%), coagulase negative staphylococcus (6.4%), except the unidentified gram- positive bacillus (21.4%). The contamination rate was higher in vaginal delivery specimens than in cesarean section specimens (4.1% vs. 0.7%, P＜0.001), and differed by collection center (0.7-25.4%, P＜0.001). Only 55% after-thaw cultures of non-conforming units were positive.
Conclusion: We determined the contamination rate of UCB in Korea in a large sample size. The results of this study could be used as baseline data at collection centers for quality control purposes. The low recovery rate of microorganisms after cryopreservation presents a possible way to rescue some non-conforming cord blood units, although further study is needed to confirm the reduction of microbiological burden.
[in Korean]
In Joo Cho, Jisook Yim, Yangsoon Lee, Myung Sook Kim, Youkyung Seo, Hae-Sun Chung, Dongeun Yong, Seok Hoon Jeong, Kyungwon Lee, Yunsop Chong
Ann Clin Microbiol 2013 March, 16(1): 45-51. Published on 20 March 2013.
Background: Trends in the isolation of enteropathogenic bacteria may differ depending on environmental sanitation. The aims of this study were to determine trends in the isolation and antimicrobial resistance patterns of enteropathogenic bacteria over the last 10 years.
Methods: We analyzed stool cultures of Salmonella spp., Shigella spp., Plesiomonas shigelloides, Yersinia spp., Vibrio spp., and Campylobacter spp. collected at Severance Hospital between 2001 and 2010. Antimicrobial susceptibility testing was performed using the disk diffusion method for nontyphoidal Salmonella (NTS) and Campylobacter.
Results: The number of specimens for stool culture significantly increased from 13,412 during 1969-1978 to 60,714 over the past 10 years, whereas the ratio of positive specimens significantly decreased from 12.9% (1,732) to 1.1% (648). The proportion of Salmonella Typhi decreased from 97.2% in 1969-1978 to 0.8% in 2001-2010, whereas the proportion of NTS increased from 2.8% to 99.2%. The proportion of Shigella among all enteric pathogens was over 50% from 1969 to 1983, while only seven strains were isolated from 2001 to 2010, with the exception of one outbreak. Campylobacter is the second most prevalent organism. The rates of susceptibility to ampicillin and cotrimoxazole were 61% and 92%, respectively, for NTS isolated from 2006 to 2010. The ciprofloxacin susceptibility rate was 79.5% for Campylobacter between 2006 and 2010.
Conclusion: The number of isolates of Salmonella Typhi and Shigella significantly decreased, while the proportion of NTS and Campylobacter increased. Continuous monitoring of ciprofloxacin-resistant Campylobacter isolates is necessary.
[in Korean]
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