Hae-Sun Chung, Miae Lee
Ann Clin Microbiol 2017 March, 20(1): 1-6. Published on 20 March 2017.
Background: The multiplex real-time PCR assay is a sensitive test for simultaneous detection of various pathogens of sexually transmitted infections (STIs). We evaluated the performance of two multiplex real-time PCR assays for six STI pathogens.
Methods: DNA samples after being used to conduct PCR for STI pathogens were stored below −70℃. Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), Mycoplasma genitalium (MG), Mycoplasma hominis (MH), Ureaplasma urealyticum (UU), and Trichomonas vaginalis (TV) were detected by multiplex real-time PCR with GeneFinder STD I (CT/NG/UU)/II (MG/MH/TV) Multiplex Real-time PCR Kits (Infopia, Korea; GeneFinder assay) and Real-Q CT&NG/ MH&TV/MG&UU Kits (BioSewoom, Korea; Real-Q assay). Discrepant results were resolved by another multiplex real-time assay, Anyplex II STI-7 Detection (Seegene, Korea). Any two positive results for the assays were considered true positive.
Results: Among 81 samples, the GeneFinder assay detected 63 pathogens from 45 cases (16 CT, 2 NG, 6 MG, 20 MH, 18 UU, and 1 TV) and Real-Q assay detected 66 pathogens from 47 cases (16 CT, 2 NG, 8 MG, 20 MH, 19 UU, and 1 TV). For the results of positive cases and negative cases, the overall concordance rate between the two multiplex real-time assays was 93.8% (Kappa=0.87). For each pathogen, the agreement rates of the two assays ranged from 97.5 to 100% (Kappa＞0.8).
Conclusion: There was no significant difference between the results of GeneFinder assay and Real-Q assay. Both multiplex real-time PCR assays can be useful methods for the detection of STI pathogens in clinical laboratories.
[in Korean]
Seung-Wook Kim, Jung-Hyun Byun, Sunjoo Kim
Ann Clin Microbiol 2017 March, 20(1): 7-12. Published on 20 March 2017.
Background: Prolonged transport or poor accessibility of blood culture equipment during night time may cause delayed entry of blood culture bottles. The effect of prestorage conditions on time to detection (TTD) for the blood culture was evaluated for the important gram-negative lactose nonfermentative bacteria.
Methods: Three different clinical isolates of Pseudomonas aeruginosa, Acinetobacter baumannii, Stenotrophomonas maltophilia, and Burkholdera cepacia were diluted to 150 CFU/mL and 15 CFU/mL and inoculated into standard aerobic bottles. These were stored at 25℃ and at 37℃ for 0, 6, 12, 18, and 24 h. They were entered to BacT/Alert 3D Systems (bioMérieux Inc.) and TTD was monitored for each condition.
Results: At the 150 CFU/mL concentration, P. aeruginosa and A. baumannii showed false-negative for the bottles prestored at 37℃ for 18 h and 24 h, respectively. However, there was no false-negative for S. maltophilia or B. cepacia at any prestorage conditions. There was a significant decrease of TTD for all experimental microorganisms except P. aeruginosa prestored for 24 h either at 25℃ or at 37℃ (P＜ 0.05).
Conclusion: Delayed entry may cause false-negative, especially for the high level of bacteremia of P. aeruginosa or A. baumannii when the bottles are stored at 37℃ for ≥18 h. TTD could be reduced by prestorage of the bottles at 37℃ until 12 h without false-negative for nonfermentative bacteria.
[in Korean]
Hyerim Kim, Yun Seong Kim, Kye-Hyung Kim, Namhee Kim, Hyung Hoi Kim, Chulhun L. Chang, Jongyoun Yi
Ann Clin Microbiol 2017 March, 20(1): 13-16. Published on 20 March 2017.
The genus Gordonia is one of the mycolic acid-containing aerobic actinomycetes. This genus has 38 named species that are widespread in the natural environment; however, Gordonia species rarely cause human infections. A 76-year-old woman presented with cough and sputum for over 1 year and was suspected of having nontuberculous mycobacterial (NTM) lung disease. An NTM isolate from the sputum was initially identified as Mycobacterium lentiflavum or Mycobacterium genavense by genotypic identification targeting internal transcribed spacer (ITS). However, the isolate was finally confirmed as Gordonia otitidis by sequencing of 16S rRNA, gyrB and secA1 genes. In patients with suspected NTM lung disease, the etiologic agent might be an organism other than NTM such as G. otitidis but still be identified as NTM without sequencing of 16S rRNA or other genes. Especially in case that a possible NTM isolate is identified as M. lentiflavum or M. genavense by the genotypic method targeting ITS, additional genotypic tests such as sequencing of 16S rRNA and other genes would be necessary for more reliable identification.
Namhee Kim, Hyun-Ji Lee, Jongyoun Yi, Su Eun Park, Chulhun L. Chang
Ann Clin Microbiol 2017 March, 20(1): 17-20. Published on 20 March 2017.
Tuberculosis can occur in various organ systems and may present with diverse manifestations. We report an unusual case of mediastinal tuberculoma in a 3-month-old boy who presented to the hospital after experiencing fever, cough, and progressive pneumonia for two weeks. The chest computed tomography scan indicated a mediastinal mass suggesting lymphoma. However, histological analysis confirmed that the mass was caused by tuberculosis. The present report describes the delayed diagnosis of a disease due to an uncommon presentation. Misdiagnosing unusual cases of tuberculosis results in treatment delays and may lead to an increase in morbidity. Therefore, we suggest that tuberculosis should be included in the differential diagnosis for children presenting with a mediastinal mass, especially in areas with a high prevalence of tuberculosis.
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