Sunjoo Kim
Ann Clin Microbiol 2011 December, 14(4): 119-125. Published on 20 December 2011.
Serological methods for the epidemiological study of Streptococcus pyogenes, such as T-, or M-typing, were replaced by emm typing in the 2000s. The frequency of emm types may differ according to geographical area and study period. Erythromycin resistance rates and the prevalence of erythromycin-resistant phenotypes in several countries are surveyed, and common emm genotypes associated with erythromycin resistance are described for each country. There is no correlation between erythromycin resistance and macrolide use in Korea. S. pyogenes is thought to cause severe illness, such as streptococcal toxic shock syndrome (STSS) and necrotizing fasciitis. The mortality rate of STSS is about 50%, and there have been several hundred victims of STSS in Japan in the last 2 decades. The resistance rate to macrolides peaked at 50% in 2002, and currently, ＜10% of strains exhibit macrolide resistance in Korea. However, the erythromycin resistance rate recently exceeded 90% in China. Considering increases of travel between neighboring countries, a vigilant survey to monitor these highly virulent and antibiotic-resistant strains is necessary.
Kon-Hee Lee, Wonkeun Song, Min-Jeong Park, Jeongwon Hyun, Hyun Soo Kim, Kyu Man Lee
Ann Clin Microbiol 2011 December, 14(4): 126-130. Published on 20 December 2011.
Background: We compared the BACTEC Peds Plus (Becton Dickinson, USA) and BacT/Alert PF (bioMerieux, France) pediatric blood culture bottles in the context of recovery and time to detection (TTD) of bacteria and fungi from pediatric patients.
Methods: Blood samples were collected for culture from pediatric patients who were hospitalized during 2010 at a university hospital. BACTEC Peds Plus and BacT/Alert PF bottles were placed in the BACTEC FX and BacT/Alert 3D blood culture system, respectively, and tested for 5 days. Bottles flagged by instruments as positive were removed from the instruments and the TTDs were recorded.
Results: A total of 5,018 sets (1 set, 1 BACTEC Peds Plus and 1 BacT/Alert PF) were evaluated. Overall, the recovery proportions for BACTEC Peds Plus and BacT/Alert PF bottles were 57% (134/195) and 69% (112/195), respectively. There was a significant difference between the 0.38% contamination rate in BacT/ Alert PF bottles and the 0.16% contamination rate in BACTEC Peds Plus bottles (P=0.035). The average TTD for all microorganisms was significantly decreased for the BACTEC Peds Plus bottles (P=0.021), but was increased for Candida parapsilosis compared to the results for the BacT/Alert PF bottles (P=0.028).
Conclusion: We conclude that the rate of detection and contamination is higher when BacT/Alert PF bottles are used than when BACTEC Peds Plus bottles are used for pediatric blood culture. The BACTEC Peds Plus bottles detect nearly all enrolled microorganisms significantly faster than do the BacT/Alert PF bottles.
[in Korean]
Ji Youn Sung, Hye Hyun Cho, Kye Chul Kwon, Sun Hoe Koo
Ann Clin Microbiol 2011 December, 14(4): 131-137. Published on 20 December 2011.
Background: Outbreaks of carbapenem resistant P. aeruginosa give rise to significant therapeutic challenges for treating nosocomial infections. In this study, we analyzed carbapenem resistance mechanisms in carbapenem resistant and clonally different P. aeruginosa strains. We analyzed chromosomal alterations in the genes of OprD and efflux system regulatory proteins (MexR, NalC, NalD, MexT, and MexZ). We also investigated chromosomal alterations in the quinolone resistance-determining region (QRDR) for quinolone resistance mechanisms.
Methods: Twenty-one clonally different P. aeruginosa strains were isolated by repetitive extragenic palindromic sequence-based PCR (rep-PCR). PCR and DNA sequencing were conducted for the detection of β-lactamase genes and chromosomal alterations of efflux pump regulatory genes, oprD, and QRDR in gyrA, gyrB, parC, and parE.
Results: Only one (P28) of the 21 strains harbored blaVIM-2. Two isolates had mutations in nalD or mexZ that were associated with efflux pump overexpression. Chromosomal alterations causing loss of OprD were found in 4 out of 21 carbapenem resistant P. aeruginosa strains. Nine of 10 imipenem and ciprofloxacin resistant strains had alterations in gyrA and/or parC.
Conclusion: Carbapenem resistance in P. aeruginosa was mediated by several mechanisms, including loss of the OprD, overexpression of efflux systems, and production of carbapenemase. Resistance to quinolone is frequently caused by point mutations in gyrA and/or parC.
[in Korean]
Min-Kwon Jung, Wee-Gyo Lee, Myung-Hwa Park
Ann Clin Microbiol 2011 December, 14(4): 138-143. Published on 20 December 2011.
Background: Asymptomatic vancomycin-resistant enterococci (VRE) colonization precedes infection. VRE- colonized patients serve as silent reservoirs of enterococci that go on to colonize other patients. Rapidly identifying colonized patients is crucial to prevent the spread of VRE. The culture-based method of VRE screening is time-consuming. We evaluated the diagnostic performance of a recently developed multiplex real-time PCR for the detection of VRE.
Methods: We obtained 105 rectal swabs from patients who were being monitored for carriage of VRE. After 24 hour incubation of swabs in enterococcosel broth (EB) supplemented with 6 μg/mL vancomycin, multiplex real-time PCR was performed using the AnyplexTM VanR Real-time Detection (VanR) kit (Seegene, Inc., Seoul, Korea). The results of multiplex real-time PCR were compared to those of culture. We evaluated the specificity and detection limits of multiplex real-time PCR using VanR for VRE.
Results: A total of 96/105 (91.4%) samples were VRE positive according to multiplex real-time PCR with EB while 85/105 (80.9%) samples were positive in culture. Eleven discordant results (10.4%) (multiplex real-time PCR positive, culture negative) were noted. All non-enterococcal bacteria and vancomycin-susceptible enterococci were negative. The DNA detection limits of VanR were 0.035 pg per reaction (3 μL) for Enterococcus faecium and 0.35 pg for Enterococcus faecalis.
Conclusion: The application of multiplex real-time PCR after EB incubation allows rapid and sensitive detection in 26-28 hours for VRE screening from rectal swabs. This method could facilitate the timely implementation of contact isolation to prevent the spread of VRE.
[in Korean]
Seri Jeong, Ji Yeon Park, Sang Hoon Han, Yangsoon Lee, Dongeun Yong, Kyungwon Lee, Yunsop Chong
Ann Clin Microbiol 2011 December, 14(4): 144-147. Published on 20 December 2011.
A 60-year-old man presented with a 1-day history of fever, vomiting, and diarrhea. He was diagnosed with severe septic shock on the basis of a body temperature of 38.9℃, heart rate of 92/min, respiratory rate of 25/min, WBC count of 22,970/μL, C-reactive protein (CRP) level of 136 mg/L, blood urea nitrogen (BUN) of 34.0 mg/dL, and creatinine of 2.98 mg/dL. On blood culture, Gram-positive cocci were detected in all 6 bottles. Small grayish non-hemolytic colonies were found on blood agar plates after incubation at 37℃ for 2 days. The isolates were negative for catalase and L-pyrrolidonyl-β-naphthylamide hydrolysis, and positive for bile-esculin and leucine aminopeptidase activity. The strain was identified as Streptococcus gallolyticus subsp. pasteurianus using Vitek 2 GP II systems. We performed 16S rRNA gene sequencing and detected 100% identity with S. gallolyticus subsp. pasteurianus strain CIP 107122T (1,345/ 1,345-bp). The patient recovered after receiving ampicillin-sulbactam. This is the first report of phenotypic and genetic identification of S. gallolyticus subsp. pasteurianus causing severe septic shock in a Korean patient.
Mi Hyun Bae, Seung Namgoong, Dongheui An, Mi-Na Kim, Sung-Han Kim, Ki-Ho Park, Sung-Gyu Lee
Ann Clin Microbiol 2011 December, 14(4): 148-152. Published on 20 December 2011.
Cryptococcus is an opportunistic pathogen that mainly affects immunocompromised hosts and, less frequently, immunocompetent hosts. It causes serious morbidity and mortality due to systemic infections such as meningoencephalitis and pulmonary infection. Urinary involvement of Cryptococcus is sometimes reported among cases of disseminated cryptococcosis in AIDS patients, but no such reports have been published in Korea. We report two cases of cryptococcuria that developed in a 71-year old female with diabetes and liver cirrhosis and in a 50-year old male who received a liver transplant due to HBV-associated hepatic failure. The female patient had received prednisolone for 12 days before we detected C. neoformans in urine culture. Even though no antifungal therapy was indicated for cryptococcuria, following urine culture became negative, but still positive for cryptococcal antigen on hospital day 25. Her blood, CSF culture, and antigen tests were negative, and therefore she was diagnosed with isolated cryptococcuria. The male patient had received prednisolone and tacrolimus for 10 days before sputum and urine cultures became positive for C. neoformans. He had ill defined nodules and pleural effusion in both lungs on chest CT. His cryptococcuria was sustained for over 2 months, despite receiving amphotericin B treatment. His cryptococcuria seemed to be a symptom of disseminated cryptococcosis.
Jayoung Kim, Yeon-Joon Park, Soyoung Shin, Yonggoo Kim, Sun Hee Park
Ann Clin Microbiol 2011 December, 14(4): 153-157. Published on 20 December 2011.
Elizabethkingia meningoseptica ( Chryseobacterium meningoseptica) is a ubiquitous Gram-negative bacillus in the natural and hospital environments. This microorganism causes neonatal meningitis but rarely causes infections in adults, with most adult cases occurring in severely immunocompromised patients. Since E. meningoseptica is inherently resistant to the usual empiric therapy aimed at Gram-negative bacilli and MIC breakpoints for resistance and susceptibility of E. meningoseptica have not been established by the Clinical and Laboratory Standards Institute, it is very difficult to select effective antibiotics for the treatment of E. meningoseptica infection. We report here three cases of E. meningoseptica isolates (two from blood and one from CSF) from adult patients admitted to Seoul St. Mary’s hospital over a 3-year period. To the best of our knowledge, this is the first report of adult meningitis due to E. meningoseptica in Korea.
[in Korean]
