Jayoung Kim, Yeon-Joon Park, Nam Yong Lee, Chulhun L . Chang, Miae Lee, Jong Hee Shin
Ann Clin Microbiol 2012 December, 15(4): 117-124. Published on 20 December 2012.
Background: We evaluated the performance of the AdvanSure MDR-TB GenoBlot Assay kit (AdvanSure MDR-TB, LG Life Science, Korea) to detect mutations related to rifampin (RFP)- and isoniazid (INH)-resistant Mycobacterium tuberculosis complex in respiratory specimens.
Methods: From February 2010 to June 2010, a total of 542 M. tuberculosis clinical isolates were collected from pulmonary tuberculosis patients in six university hospitals across Korea. We analyzed the conventional drug susceptibility testing (DST) and compared the results with those of the AdvanSure MDR-TB.
Results: Compared with the conventional DST, the overall agreement rates, sensitivity, and specificity were 98.2% (532/542), 84.6% (33/39), and 99.2% (499/503), respectively, for RFP resistance and 96.1% (521/542), 79.7% (59/74), 98.7% (462/468), respectively, for INH resistance. The three common rpoB mutations were rpoB S531L (53.8%), rpoB D516V (15.4%) and rpoB H526R (7.7%) in RFP-resistant strains. For INH resistance, the katG S315T mutation (58.1%) was the most common, followed by inhA C-15T (23.0%) and katG S315N (4.1%).
Conclusion: The AdvanSure MDR-TB showed high concordance with the conventional DST and would be helpful for early detection of RFP and INH resistance, although it requires improved sensitivity.
[in Korean]
Se Jin Oh, Miae Lee
Ann Clin Microbiol 2012 December, 15(4): 125-130. Published on 20 December 2012.
Background: Catheter-related bloodstream infection (CRBSI) is one of the leading types of infection, with a significant morbidity and mortality rate. We evaluated the differential time to positivity (DTP) and semi-quantitative culture of catheter segments (SQCC) as a method for diagnosing CRBSI.
Methods: From January 2010 to August 2011, 155 positive paired blood cultures which had the same organism isolated from blood cultures drawn simultaneously through the central venous catheter (CVC) and the peripheral vein were included. Positive DTP represents a DTP of least 120 min earlier for the time to detection of CVC draw than that of a peripheral vein draw. We evaluated the clinical utility of DTP and SQCC for diagnosing CRBSIs, which were further divided into two groups: confirmed (either by DTP or SQCC) and non-confirmed CRBSIs (neither DTP nor SQCC positive).
Results: Sixty-five percent (100/155) of episodes were confirmed to CRBSIs. In CRBSIs, Gram-positive cocci accounted for 61% of cases, non-fermenting Gram-negative bacilli represented 10%, Enterobacteriaceae for 10%, yeasts for 15%, and others for 4%. Among the confirmed CRBSI cases, 22 were both positive with DTP and SQCC, 30 cases were positive with DTP only, 12 cases were positive with SQCC only, and 36 cases which did not undergo SQCC analysis were DTP positive. The sensitivities of the DTP and SQCC techniques were 88.0% (88/100) and 53.1% (34/64), respectively.
Conclusion: The differential time to positivity was more sensitive than the semi-quantitative culture of catheter segments for the diagnosis of CRBSIs. DTP is useful for diagnosing CRBSIs without removal of the catheter.
[in Korean]
Jonghwa Yum, Hee Bong Shin, Dongeun Yong, Yunsop Chong
Ann Clin Microbiol 2012 December, 15(4): 131-138. Published on 20 December 2012.
Background: Metallo-β-lactamase-mediated carbapenem resistance has been increasingly reported in Pseudomonas, Acinetobacter and other Gram-negative bacilli (GNB) in many countries. A few studies showed highly variable structure of MBL-gene cassette-carrying integrons. The aim of this study was to determine the structure of blaVIM-2-carrying integrons in Pseudomonas and Acinetobacter.
Methods: blaVIM-2-carrying GNB were isolated at a Korean hospitals during the years 1995-1999 and 2005. The size of blaVIM-2-carrying integrons was estimated by the PCR products. Representative integrons were sequenced by the dideoxy-chain termination method. The MICs of antimicrobial agents were tested by the CLSI agar dilution methods.
Results: During the years 1995-1999 and 2005, the approximate size of the blaVIM-2-carrying class 1 integrons was 3-7 kb in 35 Pseudomonas isolates and 3-5 kb in 24 Acinetobacter isolates. The integrons carried one-five resistance gene cassettes in addition to the blaVIM-2 cassette. Other resistance gene cassettes found were blaOXA-1, aacA1, aac(6’)-I, and aac(6’)-II. Interestingly, sequences homologous to part of a putative class II intron were inserted into the recombination site of the last cassette in four of nine integrons. The class 1 integron from P. aeruginosa isolates had fused orf/IntI1 in a downstream leftward inverted repeat (IRi).
Conclusion: According to period, the size and structure of blaVIM-2-carrying integrons are quite variable, but an identical one is also present in a different genus, indicating high mobility of the blaVIM-2 cassette and horizontal transfer of the whole integron. We suggest that the class 1 integron containing the blaVIM-2 gene is spreading horizontally among Gram- negative bacilli and is undergoing continuous development in Korea.
[in Korean]
Kyoung-Jin Park, Kyung Sun Park, Soo-Han Choi, Yae-Jean Kim, Chang-Seok Ki, I-Seok Kang, Nam Yong Lee
Ann Clin Microbiol 2012 December, 15(4): 139-142. Published on 20 December 2012.
Blood culture-negative infective endocarditis (CNE) can be a diagnostic dilemma. Herein, we report a case of CNE caused by Haemophilus parainfluenzae identified only via 16S rRNA sequence analysis directly from valve tissue. A 17-year-old boy presented with high spiking fever for one month. Pansystolic murmur (Grade III) and vegetation (0.65×0.26 cm and 0.62×0.55 cm) on the anterior mitral valve leaflet via transesophageal echocardiogram suggested the diagnosis of infective endocarditis (IE). However, blood culture performed on admission was negative even after 2 weeks of incubation. Gram stain and culture of a direct tissue specimen failed to identify causative microorganism, while 16S rRNA gene sequences (548 bp) showed 100% identity with those of Haemophilus parainfluenzae (GenBank: FJ939586.1). The 16S rRNA sequence analysis with a direct tissue specimen might be useful in cases of CNE.
Moon Suk Choi, Dal Sik Kim, Sam Im Choi, Yong Gon Cho, Hye Soo Lee
Ann Clin Microbiol 2012 December, 15(4): 143-146. Published on 20 December 2012.
Arcanobacterium haemolyticum, a aerobic Gram-positive rod, has been described as an unusual pathogen causing soft tissue infections such as pharyngotonsillitis, chronic ulcer and cellulitis. In addition, the microorganism causes deep-seated infection and systemic disease including endocarditis, vertebral osteomyelitis and sepsis in patients with predisposing conditions such as diabetes mellitus. Since colonies and microscopic findings of A. haemolyticum might be confused with those of streptococci and coryneform bacteria, and it is usually isolated with other microorganisms, it is often considered to be normal flora or a contaminant in wound infections, resulting in missed or delayed diagnosis. Streptococcus agalactiae infections in neonates and pregnant women have been well recognized. However, invasive S. agalactiae infections in non-pregnant older adults with chronic medical conditions, particularly diabetes mellitus, are increasing. We report a case of diabetic foot ulcer due to A. haemolyticum and S. agalactiae in an uncontrolled diabetes mellitus patient.
[in Korean]
Ju Hyun Kong, Sung Hyun Shin, Su Eun Park, Hee Ju Park, Jongyoun Yi, Shine Young Kim, Seung Kook Son
Ann Clin Microbiol 2012 December, 15(4): 147-150. Published on 20 December 2012.
Neisseria flavescens has been rarely reported as a pathogen in the literature. We experienced a case of N. flavescens bacteremia and lung abscess co-infected with Streptococcus sanguis in patient with idiopathic hypereosinophilic syndrome. A 15-year-old boy was diagnosed with idiopathic hypereosinophilic syndrome complicated with pulmonary thromboembolism. He was given systemic steroids and thrombolytics. After 8 weeks of therapy, a lung abscess appeared on the plain chest radiograph. We treated him with empirical antibiotics and carried out surgical drainage. Two types of microorganisms were cultured from both blood and pus samples, obtained in the first day of hospitalization. Pus was aspirated from the lung abscess with an aseptic technique. Neisseria species and S. sanguis were identified using traditional methods. To confirm the identity of the Neisseria species, we conducted further testing using 16S ribosomal ribonucleic acid sequencing whereupon N. flavescens was identified. This is the first case report of pulmonary infection caused by N. flavescens. We suggest that N. flavescens may act as a pathogen.
Kyung-Min Lee, Ji Yeon Ham, Bo-Young Seo, Yu Kyung Kim, Won-Kil Lee
Ann Clin Microbiol 2012 December, 15(4): 151-153. Published on 20 December 2012.
Exflagellation of the malaria parasite microgametocyte usually occurs in the gut cavity of Anopheles mosquitoes following an infective blood meal. Exflagellation is a very rare event in human blood. Due to its rarity, the appearance of this structure in a peripheral blood smear will easily create a diagnostic dilemma. We report a case of malaria with exflagellated microgametes in human blood that was initially mistaken for a double infection of Plasmodium and another blood flagellate. The patient was a 29-year-old Parkistani man presenting with fluctuating fever accompanied by chills and fatigue for 4 days. Initial peripheral blood smear examination showed a number of Plasmodium ring forms, trophozoites, and gametocytes. Additionally, several filamentous structures resembling blood flagellates were seen. With these features, an initial diagnostic impression of combined infection of malaria and blood flagellate was made. Later, we determined that these structures resembling blood flagellates were exflagellated microgametes of malarial parasite. Therefore, the knowledge that exflagellation may appear in human blood with Plasmodium species infection and being more familiar with differentiation of the morphologic features of other species infection can prevent further possible misinterpretation.
[in Korean]
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