Su Geun Lee, Minwoo Kim, Gyu Yel Hwang, Gilsung Yoo, Young Uh
Ann Clin Microbiol 2017 December, 20(4): 81-89. Published on 20 December 2017.
Background: Meningitis is a clinically important disease because of its high mortality and morbidity. The epidemiology of this disease has changed remarkably due to the introduction of pneumococcal vaccines and Haemophilus influenzae type b (Hib) conjugate vaccine. Therefore, it is required to continuously monitor and research the organisms isolated from cerebrospinal fluid (CSF) cultures.
Methods: We analyzed trends of bacteria and fungi isolates obtained from CSF cultures between 1997 and 2016 in a tertiary care hospital according to year, month, gender, and age.
Results: Out of a total of 38,450 samples, we identified 504 (1.3%) isolates. The isolation rate in the first tested decade (1997-2006) ranged from 1.3% to 3.1%, while that in the second decade (2007-2016) ranged from 0.4% to 1.5%. The most common organisms was coagulase-negative staphylococci (CoNS) (31.9%), followed by Staphylococcus aureus (9.5%), Streptococcus pneumoniae (7.5%), Acinetobacter baumannii (5.8%), and Mycobacterium tuberculosis (5.8%). Monthly isolation rates were highest in May and July and lowest in February and December. Male to female ratio was 1.5:1. The isolation rates of S. pneumoniae, Enterococcus faecium, and Escherichia coli were similar in children and adults, but those of S. aureus, E. faecalis, A. baumannii, Pseudomonas aeruginosa, M. tuberculosis, and Cryptococcus neoformans were higher in adults than in children.
Conclusion: During the last two decades, the isolation rate of CSF culture per year has decreased, with monthly isolation rates being highest in May and July. CoNS, S. aureus, and S. pneumoniae were most common in males, whereas CoNS, S. pneumoniae, and M. tuberculosis were most common in females. While Group B Streptococcus was most common in infants younger than 1 year, S. aureus and C. neoformans were more common in adults.
[in Korean]
Choon-Mee Kim, In Sun Choi, Sook Jin Jang, Na-Ra Yun, Dong-Min Kim, Donghoon Lim, Young-Joon Ahn, Seong Ho Kang, Geon Park, Dae Soo Moon
Ann Clin Microbiol 2017 December, 20(4): 90-96. Published on 20 December 2017.
Background: Tigecycline resistance has emerged recently and has shown diverse mechanisms. The aim of this study was to assess the role of efflux activity in tigecycline resistance in 120 clinical isolates of A. baumannii using two
methods: the H33342 accumulation assay and adeB real-time reverse transcriptase polymerase chain reaction. In addition, we analyzed the correlation between the expression level of adeB and H33342 accumulation level. Methods: A. baumannii clinical isolates was divided into tigecycline-resistant (49 strains), intermediate (40 strains), and susceptible (31 strains) groups. The H33342 accumulation was measured in the absence or presence of the efflux pump inhibitor carbonyl cyanide 3-chlorophenylhydrazone (CCCP). Real-time RT- PCR was performed to determine the relative expression of the adeB gene in A. baumannii clinical isolates.
Results: The level of H33342 accumulation in the resistant group was relatively lower than those in the other groups. The addition of CCCP caused a significantly increased fold change in H33342 accumulation in the tigecycline-resistant group. Significant difference in the fold change level in H33342 accumulation was found between tigecycline-susceptible and resistant isolates. Those findings support the role of efflux pumps of which substrates are H33342 in the resistance of tigecycline. Significant differences in the relative expression levels of adeB were shown between tigecycline-susceptible and resistant groups also.
Conclusion: The results showed that several efflux pumps of which substrates were H33342 can contribute to tigecycline resistance. The adeB overexpression can also contribute to tigecycline resistance. It is possible that efflux pumps other than adeB efflux pumps contribute to tigecycline resistance because there was no correlation between fold change level in H33342 accumulation and adeB expression level.
Mi-Kyung Lee, Heungsup Sung, Ah Ra Cho, Hyun Young Chi
Ann Clin Microbiol 2017 December, 20(4): 97-102. Published on 20 December 2017.
Background: Infection by the intracellular bacteria Mycoplasma pneumoniae, Chamydophila pneumoniae, and Legionella pneumophila are common causes of community-acquired pneumonia (CAP). This study describes the evaluation of a new multiplex real-time PCR test, EuDxTM-PN MLC Detection Kit (EUDIPIA), which allows the simultaneous detection of M. pneumoniae, C. pneumoniae, and L. pneumophila in respiratory samples.
Methods: A total of 353 samples were tested using three PCR kits: multiplex PCR (Seeplex PneumoBacter ACE Detection Kit) and two multiplex real-time PCR (EuDxTM-PN MLC Detection Kit and AnyplexTM II RB5 Detection Kit). The results were considered true positives (expanded standard) for M. pneumoniae, C. pneumoniae, and L. pneumophila if they were positive according to any of the three tests.
Results: The sensitivity and specificity of EuDxTM-PN MLC Detection Kit were 93.3-100% and 100%, respectively. The agreement rate and Cohen’s kappa coefficient (value) between EuDxTM-PN MLC Detection Kit and AnyplexTM II RB5 Detection Kit for M. pneumoniae, C. pneumoniae, and L. pneumophila were 70-100% and 0.82-1, respectively.
Conclusion: These results demonstrate that the EuDxTM-PN MLC Detection Kit is a sensitive, specific, and useful screening tool for the detection of atypical pathogens in respiratory samples and can be helpful in selecting appropriate antimicrobial therapy for patients with respiratory infection.
[in Korean]
Dong-Hyun Lee, Hyoshim Shin, Sunjoo Kim
Ann Clin Microbiol 2017 December, 20(4): 103-108. Published on 20 December 2017.
Background: Group B Streptococcus (GBS) can be transmitted to neonates during delivery through the birth canal. As awareness of neonatal GBS infections is increasing, more rapid and efficient screening tests are required. The aim of this study was to evaluate the performance of ChromID STRB (bioMérieux, France) and PCR compared with the standard culture method.
Methods: Recto-vaginal swabs were collected from 775 pregnant women from April 2016 to March 2017. Cotton swab cultures were grown in LIM broth overnight and then subcultured onto blood agar plates and ChromID STRB. PCR was carried out to detect atr genes specific for GBS.
Results: The carrier rate of GBS was 5.9% (46/775). The sensitivity, specificity, positive predictive value, and negative predictive value were 83.8%, 99.3%, 86.1%, and 99.2%, respectively, for ChromID STRB and 89.2%, 99.6%, 91.7%, and 99.5%, respectively for PCR. Both ChromID STRB and PCR detected 6 more cases compared to the standard culture.
Conclusion: Chromogenic agar, ChromID STRB, and PCR using the atr gene showed excellent performance to screen for GBS. To administer prophylactic antibiotics efficiently, either selective chromogenic agar or PCR could be used in addition to the standard culture.
[in Korean]
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