Background: Previous antibiotic exposure may inhibit the growth of microorganisms in blood culture bottles. The authors investigated the frequency of previous antibiotic usage and analyzed the relationships among antibiotic usage, microbiological culture results and mortality of sepsis patients. Methods: From April to May 2011, all blood cultures requested from inpatients were analyzed according to the admitted ward and antibiotic prescription records. The BacT/Alert 3D system (bioMerieux Inc.) was used with a standard bottle (SA, SN) for blood culture. Results: Of 900 inpatients, 48% had been receiving antimicrobial agents when blood cultures were ordered. This group had a significantly higher mortality rate (36.2%) compared to the patients who had not received antibiotics (11.1%). Gram-negative rod bacteremia (37.1%) and candidemia (100%) resulted in a significantly higher mortality rate compared to Grampositive cocci bacteremia (16.4%). In the analysis of 21 cases resulting in death, 15 (71.4%) patients died before or on the date when blood culture results were reported. Conclusion: Patients who receive antibiotics prior to blood collection may be at a higher risk for mortality. In the present study, Gram-negative rod bacteremia and candidemia cases showed a rapid progression of sepsis as indicated by Gram staining and thus should be regarded seriously. (Korean J Clin Microbiol 2012;15:21-26)
Background The female genital tract is equipped to deal with a variety of foreign substances including a wide array of microorganisms. It is important to consider Candida-bacterial interactions in balance between healthy colonization versus vaginitis. The objectives of this study were to evaluate the association between microorganism distribution and vaginitis, and to investigate the possibility of an interaction between vaginal Candida and other microorganisms in female genital tract. Methods A total of 516 vaginal secretions were collected between October 2008 and June 2010 from patients with suspected vaginitis. Identification of Candida species and detection of 6 fastidious microorganisms (Trichomonas vaginalis, Neisseria gonorrhoeae, Chlamydia trachomatis, Mycoplasma hominis, Mycoplasma genitalium, and Ureaplasma urealyticum) were performed using a VITEK 2 system (bioMérieux, Inc., Hazelwood, MO, USA) and multiplex PCR (Seegene, Biotechnology, Inc., Seoul, Korea), respectively. Results M. genitalium, U. urealyticum, and C. trachomatis were more often detected in association with vaginal candidiasis. A statistically significant association between Candida and M. genitalium was observed (P<0.05). N. gonorrhoeae was detected less often in women with vaginal candidiasis. Conclusion The results of this study suggest the possibility that vaginal Candida may associate with some microorganisms in patients with vaginitis. Further studies will be required to define the Candida-bacterial interactions and its mechanisms.
Background Infectious vaginitis is caused primarily by three different groups of microbial pathogens (Trichomonas vaginalis, Candida spp., and Gardnerella vaginalis). The objective of this study was to compare the Affirm VPIII assay using a DNA hybridization technique with the Papanicolaou (Pap) smear test and the Gram stain in the detection and identification of these three organisms. Methods A total of 300 vaginal samples were collected from women that were either symptomatic for vaginitis or asymptomatic women that were being seen for routine obstetric or gynecological care. The presence of T. vaginalis, Candida spp., and G. vaginalis was evaluated by using the Affirm VIII assay (Becton Dickinson, USA), Pap smear test, and Gram stain method, respectively. Results With the Affirm VPIII assay, 1 (0.3%) patient tested positive for T. vaginalis, 99 (33.0%) patients were positive for G. vaginalis, and 18 (6.0%) were positive for Candida spp. The detection rates of Trichomonas infection, bacterial vaginosis and candidiasis by the Pap smear test and Gram stain method were 0.7% versus 0%, 16.3% versus 35.7%, and 1.7% versus 9.7%, respectively. The differences between the detection rates of the above three organisms between the Pap smear test and the Gram stain method were statistically significant (p<0.05). Conclusion The Affirm VPIII assay was more sensitive than the Pap smear test and more specific than the Gram stain method for the detection and identification of these three organisms. In addition, the results of the Affirm VPIII assay are quick to obtain and are simple and easy to interpret.
The global emergence and spread of multidrug resistant bacterial infections in communities and hospitals has become an important issue in public health. The resistance rate of gram-positive cocci to vancomycin and the resistance rate of several gram-negative bacilli against cefotaxime and carbapenem have been continuously increasing. Surveillance of antimicrobial resistance is essential for providing information on the magnitude of and trend in multidrug resistance. Therefore, beginning 2011, more robust and effective management is to be legally required for six multidrug-resistant bacteria that have been linked to healthcare-related infections: vancomycin-resistant Staphylococcus aureus (VRSA), vancomycin-resistant enterococci (VRE), methicillin-resistant S. aureus (MRSA), multidrug-resistant Pseudomonas aeruginosa (MRPA), multidrug-resistant Acinetobacter baumannii (MRAB), and carbapenem-resistant Enterobactericeae (CRE). We have also performed laboratory-based sentinel surveillance for VRSA/VISA since 2002 and carbapenemase-producing Enterobacteriaceae since November, 2010. This article reviews the national surveillance programs, and molecular epidemiology of multidrug-resistant bacteria.
Cryptococcus neoformans (C. neoformans) is a ubiquitous yeast-like fungus that has been a common opportunistic human pathogen, especially in immunocompromised patients. Although skin lesions due to C. neoformans are found in 10-15% of patients with systemic cryptococcosis, primary cutaneous cryptococcosis without systemic infection is rare and now considered a distinct clinical entity. We report a case of primary cutaneous cryptococcosis in a patient with iatrogenic Cushing's syndrome. A 73-year-old woman presented with pain and discharge from lesions on her left forearm. The patient had been treated with oral corticosteroids for 20 years, and as a result had developed iatrogenic Cushing's syndrome. A skin fragment of the ulcer was cultured, and the encapsulated fungus were isolated and identified as C. neoformans using a Vitek2 system (Vitek2 ID-YST, bio Mérieux, France) and API 20C (bioMérieux). Concurrent blood and urine cultures were negative for growth. At first, she was treated with antibiotics due to suspicion of cellulitis. After surgical resection and treatment with systemic and oral fluconazole, her wound was improved with scar. Primary cutaneous cryptococcosis should be considered when skin lesions are not responsive to antibiotics and accurate identification is important for proper treatment.
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.
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.
Anaerobiospirillum succiniciproducens is a spiral-shaped, gram-negative anaerobic bacterium. A. succiniciproducens is a rare cause of bacteremia in human, especially immunocompromised patients. This organism may be mistakenly identified when using an automated bacterial identification system, and may be mistaken for Campylobacter spp. when using Gram staining. We report a case of bacteremia caused by A. succiniciproducens, which was negative for catalase, oxidase, and urease and confirmed by 16S rRNA sequencing (analysis revealed a 99% similarity), in a 69-year-old patient who was undergoing chemotherapy for treatment of a malignancy. To the best of our knowledge, this is the first report of bacteremia caused by A. succiniciproducens in Korea.
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.
Background The isolation of nontuberculous mycobacteria (NTM) has been increasing worldwide as well as its clinical importance. The aim of this study was to investigate the distribution and clinical significance of NTM that has been isolated from respiratory specimens during a recent two-year period at a tertiary hospital. Methods We analyzed respiratory samples that were obtained between January 2009 and December 2010 for AFB culture. We retrospectively reviewed the electronic medical records of these patients to obtain both clinical and radiologic information. NTM pulmonary disease was defined by using the guidelines provided by the America Thoracic Society/Infectious Diseases Society of America. Results Among the 1,601 specimens that resulted in a positive AFB culture, 310 (19.4%) were NTM. In 189 patients, the most common isolate was M. avium-intracellulare complex (MAC) (127, 67.2%), which was then followed by M. abscessus (31, 16.4%), M. fortuitum (10, 5.3%), M. kansasii (9, 4.8%), and other NTM species. Of these, 93 (49.2%) patients were diagnosed with NTM pulmonary disease. MAC, M. abscessus, and M. kansasii were more virulent than the other species. None of the cases of NTM pulmonary disease were caused by M. fortuitum, M. chelonae, M. peregrinum, M. terrae complex, or M. gordonae. Conclusion In Korea, the prevalence of NTM isolates is increasing, as are the cases of pulmonary disease. The pathogenic potential of NTM differs enormously by species and as a result the treatment of NTM lung disease depends on which species has caused the infection. The isolation and identification of NTM isolated from respiratory specimens are mandatory in order for clinical microbiology laboratories to make an accurate diagnosis and suggest the proper treatment of the NTM disease.
Background Clostridium difficile is the main etiologic agent of antibiotic-associated diarrhea and the most common cause of hospital-acquired diarrhea. Recently, the incidence of C. difficile infections (CDI) has increased and new highly virulent C. difficile strains have emerged. Therefore, accurate and rapid diagnosis is needed. We compared the results of using chromID C. difficile (chromID CD, bioMeriéux, France) with the conventional C. difficile Selective Agar (CDSA; BD, USA) for the isolation of C. difficile. Methods A total of 738 stool specimens of suspected CDI patients at the Severance Hospital from July to August 2011 were inoculated onto CDSA. Among them, 104 stool specimens revealed colonies on CDSA that were then re-inoculated onto chromID CD. The stool samples were stored at -20℃ until the time of the re-inoculation. Cultured agars were interpreted after 24 hrs and 48 hrs, respectively. Species identification was performed on the basis of colony characteristics on agar plates as well as the ATB 32A system (API System SA, France). Results The recovery rates of CDSA and chromID CD were 30.1% and 77.5% after 24 hrs, and 77.5% and 98.6% after 48 hrs, respectively. All of the C. difficile isolates were recovered as typical gray/black colonies on chromID CD. Conclusion The performance of chromID CD for the isolation of C. difficile was better than that of conventional CDSA. The chromID CD could provide easy and sensitive detection of C. difficile even after 24hrs of incubation.
Clinical isolates of Acinetobacter spp. in Korea exhibit higher antimicrobial resistance rates than in foreign countries and frequently show multi-drug resistance. Approximately 67% (272/405) of Acinetobacter baumannii isolates collected from 19 hospitals in Korea in 2008 exhibited intermediate susceptibility or resistance to imipenem and/or meropenem. The most important mechanisms in acquiring carbapenem resistance in A. baumannii in Korea are production of OXA-23 and overproduction of OXA-51, while that in non-baumannii Acinetobacter is the production of metallo-β-lactamases. All the carbapenem-resistant A. baumannii isolates were identified as clonal complex 92 and belonged to worldwide clone 2.
Background: This study compared three non-molecular methods for the detection of methicillin-resistance directly from blood cultures containing Staphylococcus aureus: penicillin-binding protein (PBP) 2a latex agglutination (LA), PBP2a immunochromatographic assay (ICA) and MRSA chromogenic medium (CM). Methods: Fifty methicillin-resistant S. aureus (MRSA) and 50 methicillin-susceptible S. aureus (MSSA) were seeded into blood-culture bottles. When isolates returned a positive signal, 5 mL of culture was added to serum separator tubes and centrifuged at 1,300 g for 10 min. The pellets were then used as the inoculum for the PBP2a LA, MRSA-CM and PBP2a ICA. The pure colony was used for PBP2a LA test, additionally. Results: The respective sensitivities and specificities were 98 and 100% for PBP2a ICA, and 100 and 100% for MRSA-CM in direct detection of MRSA from positive blood culture. The results of PBP2a LA test using pure colony were entirely compatible with those by mecA gene PCR but the PBP2a LA test using the pellets directly isolated from positive blood culture showed sometimes ambiguous agglutination; its sensitivity and specificity were 78 and 100%, if ambiguous results were scored as negative, and were 90 and 92%, if ambiguous results were scored as positive, respectively. Conclusion: For direct detection of MRSA in positive blood culture, MRSA-CM and PBP2a ICA provided excellent results. The PBP2a LA test using pure colony also gave excellent results but the PBP2a LA test by the direct method using pellet of positive blood culture was slightly less sensitive than the other two methods. (Korean J Clin Microbiol 2012;15:27-31)
Background The emergence of non-typhoidal Salmonella (NTS) with decreased susceptibilities to fluoroquinolone, ampicillin, or ceftriaxone has been reported worldwide. However, current surveillance studies of resistance among NTS in Korea are limited. Thus, the antimicrobial susceptibilities; resistance mechanisms such as extended-spectrum β-lactamase (ESBL), plasmid-mediated AmpC β-lactamase (PABL), and plasmid-mediated quinolone resistance (PMQR); and molecular epidemiologic characteristics were investigated in the present study. Methods National Institute of Health and National Veterinary Research and Quarantine Service collected NTS strains from 219 clinical and 293 non-clinical specimens from 2006 to 2008. The antimicrobial susceptibilities were determined using the Clinical and Laboratory Standards Institute disk diffusion test. ESBL, PABL, and qnr genotyping were performed using PCR and nucleotide sequencing. Pulsed-field gel electrophoresis was used for the molecular epidemiologic study. Results The resistance to ampicillin in clinical and non-clinical NTS was 49% and 18 to 47%, respectively. The resistance rates to trimethoprim-sulfamethoxazole in clinical and non-clinical NTS were 8% and 0 to 41%, respectively. The rates to extended-spectrum cephalosporin were 0 to 1%. One CTX-M-15-producing isolate and four CMY-2-producing isolates were detected. Notably, PFGE analysis showed four isolates carrying blaCMY-2, including one non-clinical strain had high clonality. Although the rate of ciprofloxacin resistance was very low, two qnrS1-carrying NTS strains were detected in non-clinical specimens. Conclusion The resistance rates to ampicillin in both clinical and non-clinical NTS were high, while those to trimethoprim-sulfamethoxazole varied depending on the specimen. NTS strains harboring CTX-M-15-type ESBL or CMY-2-type PABL were detected even though the resistance rates to cephalosporins were very low. Four NTS strains carrying the blaCMY-2-gene implied zoonotic infection. Continuous effort to minimize transfer of resistance genes in NTS is necessary.
Background Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has been used for the identification of bacteria worldwide. To our knowledge, the evaluation of MALDI-TOF MS for the identification of bacteria in Korea has not been studied. In this paper we compared the identification results of aerobic bacteria using MALDI-TOF MS to those results using conventional biochemical methods. Methods We evaluated the performance of a MALDI-TOF MS system (Bruker Daltonics, Leipzig, Germany) on consecutive aerobic isolates collected from January to February of 2011 which were identified using conventional methods (biochemical testing and commercial identification kits). Either directly smearing onto the target plate or protein extraction methods were additionally used if no reliable or discordant results were obtained. Results Among 523 isolates tested, 506 (97%) isolates had valid scores (≥2.0), 11 (2%) isolates gave intermediate scores (1.7≤ score <2.0), and 6 (1%) isolates yielded no reliable identification (score <1.7). Of the 506 valid results (score ≥2.0) by MALDI-TOF MS, the identification matched at the species level in 486 (96%) isloates, matched at the genus level in 17 (3%) isloates, and was discordant at the genus and species levels in 3 (1%) isloates. Conclusion The overall matching rate at the species level of MALDI-TOF MS was very high. When MALDI-TOF MS did not yield reliable results by direct smear, additional direct smears or protein extraction methods could be used to obtain better results. Our results showed that MALDI-TOF MS is a very useful method for the identification of aerobic bacteria isolated in clinical microbiology laboratories.
