Changing Epidemiology of Pathogenic Bacteria Over the Past 20 Years in Korea

Background@#The epidemiology of pathogenic bacteria varies according to the socioeconomic status and antimicrobial resistance status. However, longitudinal epidemiological studies to evaluate the changes in species distribution and antimicrobial susceptibility of pathogenic bacteria nationwide are lacking. We retrospectively investigated the nationwide trends in species distribution and antimicrobial susceptibility of pathogenic bacteria over the last 20 years in Korea. @*Methods@#From 1997 to 2016, annual cumulative antimicrobial susceptibility and species distribution data were collected from 12 university hospitals in five provinces and four metropolitan cities in South Korea. @*Results@#The prevalence of Staphylococcus aureus was the highest (13.1%) until 2012 but decreased to 10.3% in 2016, consistent with the decrease in oxacillin resistance from 76.1% in 2008 to 62.5% in 2016. While the cefotaxime resistance of Escherichia coli increased from 9.0% in 1997 to 34.2% in 2016, E. coli became the most common species since 2013, accounting for 14.5% of all isolates in 2016. Pseudomonas aeruginosa and Acinetobacter baumannii rose to third and fifth places in 2008 and 2010, respectively, while imipenem resistance increased from 13.9% to 30.8% and 0.7% to 73.5% during the study period, respectively.Streptococcus agalactiae became the most common pathogenic streptococcal species in 2016, as the prevalence of Streptococcus pneumoniae decreased since 2010. During the same period, pneumococcal penicillin susceptibility decreased to 79.0%, and levofloxacin susceptibility of S. agalactiae decreased to 77.1% in 2016. @*Conclusion@#The epidemiology of pathogenic bacteria has changed significantly over the past 20 years according to trends in antimicrobial resistance in Korea. Efforts to confine antimicrobial resistance would change the epidemiology of pathogenic bacteria and, consequently, the diagnosis and treatment of infectious diseases.

Nationwide Survey for Current Status of Laboratory Diagnosis of Clostridioides difficile Infection in Korea

Background@#The interest in Clostridioides difficile infection (CDI) has increased, and the choice of assays became wider since the first national survey in Korea on CDI diagnosis in 2015. We conducted a survey of the domestic CDI assays with more varied questions to understand the current situation in Korea. @*Methods@#In April 2018, about 50 questions on the current status of CDI assays and details on implementation and perceptions were written, and a survey questionnaire was administered to laboratory medicine specialists in 200 institutions. @*Results@#One-hundred and fifty institutions responded to the questionnaire, of which 90 (60.0%) including one commercial laboratory, performed CDI assays. The toxin AB enzyme immunoassay (toxin AB EIA), nucleic acid amplification test (NAAT), and C. difficile culture, glutamate dehydrogenase assay, alone or in combination with other assays, were used in 75 (84.3%), 52 (58.4%), 35 (36.0%), and 23 (25.8%), respectively, and 65 (73.0%) institutions performed a combination of two or more assays. The sensitivity of toxin AB EIA was more negatively perceived, and that on specificity was more positively perceived. The perception of sensitivity and specificity of NAAT was mostly positive. Perception on the algorithm test projected it as useful but in need of countermeasures. Sixty-three (73.3%) institutions responded that they performed surveillance on CDI. @*Conclusion@#This study provides useful evidence on the current status of CDI laboratory diagnosis in Korea as well as on items that require improvement and is thought to aid in standardizing and improving the CDI laboratory diagnosis in Korea.

Antimicrobial Resistance Patterns of Acinetobacter baumannii and Pseudomonas aeruginosa Isolated From Vulnerable Patients in Korea, 2021 / 대한임상미생물학회지

Background@#We compared the antimicrobial resistance rates (AMRs) of major glucose nonfermenting gram-negative bacilli, Acinetobacter baumannii and Pseudomonas aeruginosa, under different clinical conditions. The purpose of the study was to provide useful background data to set up infection control strategies for infection-vulnerable patients. @*Methods@#The AMRs of blood isolates were compared in various clinical conditions, using data from the Antimicrobial Resistance Surveillance System in Korea. @*Results@#A. baumannii blood isolates from patients with healthcare-associated infections, inpatients, or intensive care unit (ICU)-admitted patients consistently exhibited higher AMRs to most antimicrobials, except minocycline, tigecycline, and colistin, compared with those from patients with community-acquired infections, outpatients, or non-ICU-admitted patients, respectively. P. aeruginosa blood isolates from patients with healthcare-associated infections showed higher AMRs to most antimicrobials, except ceftazidime and aztreonam, compared with those from patients with community-acquired infections, but not compared to those from inpatients or ICU-admitted patients. @*Conclusion@#Higher AMRs were associated with A. baumannii bloodstream infections under various clinical conditions, such as healthcare-associated infections and infections in inpatients and ICU-admitted patients. Considering the high AMRs and the limited number of treatment options of A. baumannii, vigorous efforts should be used to prevent the spreading of A. baumannii infections in patients with vulnerable conditions.

Current Prevalence of the crpP Gene in Carbapenemase-Producing Pseudomonas aeruginosa Blood Isolates in Korea / 대한임상미생물학회지

Background@#Recently, CrpP enzymes have been described as a novel cause of ciprofloxacin resistance. The crpP gene encodes a novel protein that specifically confers resistance to ciprofloxacin through an adenosine triphosphate-dependent mechanism that phosphorylates the antimicrobial. In this study, the current prevalence of the crpP gene in carbapenemaseproducing Pseudomonas aeruginosa blood isolates was evaluated. @*Methods@#During the study of the Antimicrobial Resistance Surveillance System in Korea, 22 blood isolates of carbapenemase-producing P. aeruginosa were collected from nine general hospitals and two nursing homes in the year 2020. Resistance genes and phylogenic trees were analyzed with the whole genome sequencing data. @*Results@#A total of 11 P. aeruginosa blood isolates coharbored the crpP and carbapenemase genes (nine IMP-6 producers and two GES-5-producers). Nine NDM-1-producers coharbored aac(6')-Ib-cr and qnrVC1 . One GES-9-producer also carried aac(6')-Ib-cr, and one NDM-1-producer also carried qnrVC1. The phylogenic tree showed no epidemiologic link among the 22 carbapenemase-producing P. aeruginosa isolates. @*Conclusion@#This is the first report on the current prevalence of the crpP gene in carbapenemaseproducing P. aeruginosa blood isolates in Korea.

Prevalence of SARS-CoV-2 Antibody in 2,935 Healthcare Workers at 6 Major Hospitals, Daegu, Korea

Background@#In Korea, the first community outbreak of coronavirus disease 2019 (COVID-19) occurred in Daegu on February 18, 2020. This study was performed to investigate the prevalence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antibodies in healthcare workers (HCWs) at 6 major hospitals in Daegu. @*Methods@#Blood specimens of 2,935 HCWs at 6 major hospitals in Daegu from January 2021 to February 2021 were collected. Every specimen was tested for antibody against SARS-CoV-2 using both Elecsys Anti-SARS-CoV-2 electrochemiluminescence immunoassay (Roche Diagnostics, Rotkreuz, Switzerland) and R-FIND COVID-19 IgG/M/A enzyme-linked immunosorbent assay kit (SG medical Inc., Seoul, Korea) as screening tests. If 1 or more of these screening test results was positive, 2 additional antibody tests were performed using Abbott Anti-SARS-CoV-2 IgG assay (Abbott, Abbott Park, IL, USA) and cPass SARS-CoV-2 Neutralization Antibody Detection Kit (GenScript USA Inc., Piscataway, NJ, USA). If 2 or more of the total 4 test results were positive, it was determined as positive for the antibody against SARS-CoV-2. @*Results@#According to the criteria of SARS-CoV-2 antibody positivity determination, 12 subjects were determined as positive. The overall positive rate of the SARS-CoV-2 antibody was 0.41% (12/2,935). Of the 12 subjects determined as positive, 7 were diagnosed with COVID-19, and the remaining 5 were nondiagnosed cases of COVID-19. @*Conclusion@#In early 2021, the overall seroprevalence of SARS-CoV-2 antibody among HCW located in Daegu was 0.41%, and 0.17% excluding COVID-19 confirmed subjects. These results were not particularly high compared with the general public and were much lower than HCWs in other countries.

Serotyping and Antimicrobial Susceptibility of Salmonella Isolated in Korea in 2015 / 대한임상미생물학회지

BACKGROUND: Salmonella is an important pathogen that causes gastroenteritis and sepsis in humans. Recently, changes in serotype prevalence and an increase in antimicrobial resistance have been reported. This study investigated the distribution of Salmonella serotypes and determined the antimicrobial susceptibility of various strains. METHODS: We collected 113 Salmonella isolates other than Salmonella serotype Typhi from 18 university hospitals in 2015. The serotypes were identified by Salmonella antisera O and H according to the Kauffman White scheme. Antimicrobial susceptibility tests for 12 antibiotics were performed using the disk diffusion method or E-test. RESULTS: We identified 22 serotypes. Serotype group B (44.2%) was the most common, followed by groups C (34.5%) and D (21.2%). Salmonella I 4,[5],12:i:- (23.0%), S. Enteritidis (16.8%), and S. Typhimurium (12.4%) were the most common species. Resistance rates for ampicillin, chloramphenicol, ceftriaxone, and trimethoprim/sulfamethoxazole were 46.9%, 18.5%, 8.8%, and 5.3%, respectively. The intermediate resistance rate to ciprofloxacin was 29.2%. Six isolates were extended-spectrum β-lactamase (ESBL) producers, including 5 bla(CTX-M-15) and 1 bla(CTX-M-55). CONCLUSION: There have been changes in the serotype prevalence and antimicrobial resistance of Salmonella in Korea, with a high prevalence of CTX-M 15-positive strains. Continuous monitoring of Salmonella serotypes and antimicrobial resistance is warranted.

A Case of Monocular Gonococcal Conjunctivitis in an Adult Male / 계명의대학술지

Gonococcal conjunctivitis is rare in adults and, if not treated properly, can cause corneal perforation. Gonococcal conjunctivitis typically presents with a severe mucopurulent discharge, similar to that associated with viral conjunctivitis. Here, we describe a case of monocular gonococcal conjunctivitis, including its clinical characteristics and slit-lamp images, which was initially misdiagnosed as epidemic conjunctivitis. A 20-year-old man was referred to our hospital with no improvement in monocular infection and purulent ocular discharge after 2-wk treatment using antibiotic and 0.1% fluorometholone eye drops at the local ophthalmic clinic. Initially, 0.5% loteprednol eye drops were used since we suspected viral conjunctivitis. Following this treatment, conjunctival infection worsened and a yellow-white ocular discharge covered the conjunctiva and cornea surface. Additional history taking revealed that the patient had sexual contact with a prostitute 1 wk prior to symptom presentation and, after the encounter, he took antibiotics for genital discharge at the local urology clinic, but self-discontinued treatment. A Gram staining showed gram-negative diplococci and culture of collected ocular discharge from the palpebral conjunctiva revealed growth of Neisseria gonorrhoeae, confirming gonococcal conjunctivitis. Following this, the patient was systemically treated with 3rd generation cephalosporin antibiotics. After 3-d treatment, conjunctival infection and purulent ocular discharge had significantly improved. When clinical symptoms are aggravated following steroid eye drop treatment for suspected monocular viral conjunctivitis, gonococcal conjunctivitis must be considered as a differential diagnosis

BRCA1/2 mutations, including large genomic rearrangements, among unselected ovarian cancer patients in Korea / 부인종양

OBJECTIVE: We performed small-scale mutation and large genomic rearrangement (LGR) analysis of BRCA1/2 in ovarian cancer patients to determine the prevalence and the characteristics of the mutations. METHODS: All ovarian cancer patients who visited a single institution between September 2015 and April 2017 were included. Sanger sequencing, multiplex ligation-dependent probe amplification (MLPA), and long-range polymerase chain reaction (PCR) were performed to comprehensively study BRCA1/2. The genetic risk models BRCAPRO, Myriad, and BOADICEA were used to evaluate the mutation analysis. RESULTS: In total, 131 patients were enrolled. Of the 131 patients, Sanger sequencing identified 16 different BRCA1/2 small-scale mutations in 20 patients (15.3%). Two novel nonsense mutations were detected in 2 patients with a serous borderline tumor and a large-cell neuroendocrine carcinoma. MLPA analysis of BRCA1/2 in Sanger-negative patients revealed 2 LGRs. The LGRs accounted for 14.3% of all identified BRCA1 mutations, and the prevalence of LGRs identified in this study was 1.8% in 111 Sanger-negative patients. The genetic risk models showed statistically significant differences between mutation carriers and non-carriers. The 2 patients with LGRs had at least one blood relative with breast or ovarian cancer. CONCLUSION: Twenty-two (16.8%) of the unselected ovarian cancer patients had BRCA1/2 mutations that were detected through comprehensive BRCA1/2 genetic testing. Ovarian cancer patients with Sanger-negative results should be considered for LGR detection if they have one blood relative with breast or ovarian cancer. The detection of more BRCA1/2 mutations in patients is important for efforts to provide targeted therapy to ovarian cancer patients.

Comparison and Evaluation of Diagnostic Assays for Clostridium difficile Infection

BACKGROUND: Clostridium difficile is a leading causative microorganism of pseudomembranous colitis (PMC) and antibiotic-associated diarrhea. In patients who have a history of antibiotic use and diarrhea, the presence of the C. difficile toxin should be confirmed to diagnose C. difficile infection (CDI). In this study, the results of three assays for CDI, which were performed on 1,363 clinical stool samples at a tertiary hospital, were analyzed to evaluate the performance and usefulness of these assays for diagnosis of CDI. METHODS: The results of the VIDAS C. difficile Toxin A&B Immunoassay (bioMérieux SA, France), Xpert C. difficile Real-Time PCR Assay (Cepheid, USA), and ChromID C. difficile Agar (bioMérieux SA, France) culture were analyzed retrospectively. Cases were defined as CDI according to the positive Xpert assay or the positive VIDAS assay and/or culture in the presence of PMC findings after radiological imaging or endoscopic procedures. RESULTS: A total of 1,027 samples (75.8%) tested negative in all three assays, 101 samples (7.4%) tested positive in all three assays, and overall agreement among them was 82.7%. In this study, 291 cases (21.3%) were diagnosed as CDI. Sensitivity and specificity of the VIDAS assay were 38.8% and 99.3%, and those of ChromID culture were 71.5% and 96.5%, respectively. The Xpert assay showed good sensitivity (98.6%, 287/291), whereas the VIDAS assay and ChromID culture showed low sensitivities. CONCLUSIONS: These results suggest that rapid molecular diagnostic assays, such as the Xpert assay, are promising candidates for an initial diagnostic test for CDI.

First Case of Pulmonary Mycobacterium parascrofulaceum Infection in a Patient With Bronchiectasis in Korea

No abstract available.

Frequency and Clinicohematologic Characteristics of MPL W515 Mutations in Patients with Myeloproliferative Neoplasms

BACKGROUND: Recently, myeloproliferative leukemia (MPL) W515 mutations have been reported to be molecular markers for myeloproliferative neoplasms (MPNs). We studied the association between MPL W515 mutations and the clinico-hematological features of patients with MPNs. METHODS: Our study included 154 consecutive patients diagnosed with MPNs (31 had polycythemia vera [PV]; 106, essential thrombocythemia [ET]; and 17, primary myelofibrosis [PMF]). MPL W515 mutations were detected by real-time PCR and direct sequencing methods. RESULTS: The MPL W515L mutation was found in 4 patients and the MPL W515A mutation was detected in 1 patient. These 5 patients were diagnosed with JAK2 V617F-negative ET, and they accounted for 12.5% of patients with JAK2 V617F-negative ET. The patients with MPL W515-positive ET showed significantly lower hemoglobin levels and WBC counts than did patients with MPL W515-negative ET or JAK2 V617F-positive ET. CONCLUSIONS: MPL W515 mutation is a useful diagnostic marker for JAK2 V617F-negative MPNs and it is associated with specific hematologic characteristics such as lower hemoglobin levels and WBC counts.

A Case of Phoma glomerata Keratitis Occurred in Recurrent Herpes Simplex Keratitis Cicatrix

PURPOSE: To report a case of Phoma glomerata keratitis occurring in recurrent herpes simplex keratitis cicatrix. CASE SUMMARY: A 63-year-old male patient was admitted to our hospital with complaints of abrupt visual deterioration and ocular pain in his left eye. He was treated for recurrent herpes simplex keratitis in the same eye 12 years prior. Because central desmatocele was observed as a result of advanced corneal stromal melting, Gram staining, Potassium Hydroxide (KOH) mount, and culture were performed in corneal scrape specimens. On microbiological evaluation, a Phoma species was detected and Phoma glomerata was diagnosed using DNA sequencing method. Two consecutive amniotic membrane transplantations were performed with topical antifungal agents. The lesion was not improved when using topical amphotericin B and natamycin eyedrops, thus fluconazole eyedrops were used additionally. The corneal infection was resolved with central thick opacification. CONCLUSIONS: In the present case, herpetic keratitis was the main underlying causative factor because the patient had no past history of trauma. When diverse appearances of keratitis occur in herpes simplex keratitis patients, clinicians need to consider the concurrence of fungal infection, especially Phoma glomerata, a rare fungal organism.

Is the Environment of the Endoscopy Unit a Reservoir of Pathogens?

BACKGROUND/AIMS: Given the characteristic procedures involved in the endoscopy unit, the spread of pathogens is much more frequent in this unit than in other environments. However, there is a lack of data elucidating the existence of pathogens in the endoscopy unit. The aim of this study was to detect the presence of possible pathogens in the endoscopy unit. METHODS: We performed environmental culture using samples from the endoscopy rooms of 2 tertiary hospitals. We used sterile cotton-tipped swabs moistened with sterile saline to swab the surfaces of 197 samples. Then, we cultured the swab in blood agar plate. Samples from the colonoscopy room were placed in thioglycollate broth to detect the presence of anaerobes. After 2 weeks of culture period, we counted the colony numbers. RESULTS: The most commonly contaminated spots were the doctor's keyboard, nurse's cart, and nurse's mouse. The common organisms found were non-pathogenic bacterial microorganisms Staphylococcus, Micrococcus, and Streptococcus spp.. No definite anaerobe organism was detected in the colonoscopy room. CONCLUSIONS: Although the organisms detected in the endoscopy unit were mainly non-pathogenic organisms, they might cause opportunistic infections in immunocompromised patients. Therefore, the environment of the endoscopy room should be managed appropriately; moreover, individual hand hygiene is important for preventing possible hospital-acquired infections.

A Case of Beauveria Bassiana Keratitis Confirmed by Gene Sequencing

PURPOSE: To report a case of Beauveria bassiana keratitis that was confirmed by gene sequencing. CASE SUMMARY: A 70-year-old man presented to our hospital with complaints of ocular pain and deterioration of the visual acuity in his left eye after injury caused by a wood branch one week previously. Visual acuity in the left eye was 20/400 at the time of the first visit. Slit lamp examination showed a central 0.7 x 2.5-mm-sized epithelial defect surrounded by cellular infiltration in the stroma. Scraping of the corneal lesion for microbiological examinations was performed. Initial Gram stain, potassium hydroxide (KOH) mount, and culture were negative. However, fungal hyphae were observed on a KOH mount of the repeated corneal scraping specimen, and a Beauveria species was suspected based on the culture. Beauveria bassiana was confirmed using a MicroSEQ(R) D2 large-subunit ribosomal DNA fungal sequencing kit. Natamycin eye solution was initially instilled bihourly (every two hours), but the persistent epithelial defect and progressive stromal melting finally resulted in a descemetocele. Temporary and permanent amniotic membrane transplantations were performed, and amphotericin B eye solution was administered bihourly (every two hours). The ulcerous lesion gradually improved with no evidence of recurrence. CONCLUSIONS: Recently, cases of fungal keratitis have been increasing. Therefore, molecular diagnosis methods such as gene sequencing can be helpful in diagnosis and in improving the prognosis of fungal keratitis caused by rare fungi, as we found in this case.

A Multicentre Study about Pattern and Organisms Isolated in Follow-up Blood Cultures / 대한임상미생물학회지

BACKGROUND: This study analysed patterns of requests for repeated blood cultures and the microorganisms isolated in follow-up cultures. METHODS: The frequencies and intervals of repeated blood cultures performed during January and February of 2010 at seven university-affiliated hospitals in Korea were evaluated. Results of microbiological cultures at follow-up were analysed with respect to pathogen replication, immune clearance, appearance of new pathogens, and skin contaminants. RESULTS: Among 3,072 patients who received repeated blood cultures, the average number of requests was 3.2. Of the 5,241 follow-up blood culture events recorded, durations of 1, 2, and 3 days between cultures were identified for 23.1%, 21.4%, and 15.0% of events, respectively. Relative to each initial culture, persistent pathogen growth in subsequent culture(s) accounted for 2.3% of events, whereas immune clearance was confirmed in 8.5% of events. Previously undetected pathogens were isolated in 5.2% of the follow-up cultures, the majority of which grew after an interval of six days. Skin contaminants were detected in 7.6% of the repeated cultures, and 76.1% of the follow-ups displayed no growth of microorganisms. CONCLUSION: The most common numbers of repeat culture requests were two and three, and these were typically performed within three days of the initial culture. Among the follow-up cultures, new pathogens were identified in 5.2%, and the majority of this group likely presented for follow-up during a new disease episode.

Two Cases of Partial Trisomy 4p and Partial Trisomy 14q

We present clinical and cytogenetic data on 2 cases of partial trisomy 4p and partial trisomy 14q. Both patients had an extra der(14)t(4;14)(p15.31;q12) chromosome due to a 3:1 segregation from a balanced translocation carrier mother. Array analyses indicated that their chromosomal breakpoints were similar, but there was no relationship between the 2 families. Both patients showed prominent growth retardation and psychomotor developmental delay. Other phenotypic manifestations were generally mild and variable; for example, patient 1 had a short palpebral fissure and low-set ears whereas patient 2 had a round face, asymmetric eyes, small ears, a short neck, finger/toe abnormalities, and behavioral problems.

Phialemonium obovatum Keratitis after Penetration Injury of the Cornea

Phialemonium keratitis is a very rare case and we encountered a case of keratitis caused by Phialemonium obovatum (P. obovatum) after penetrating injury to the cornea. This is the first case report in the existing literature. A 54-year-old male was referred to us after a penetration injury, and prompt primary closure was performed. Two weeks after surgery, an epithelial defect and stromal melting were observed near the laceration site. P. obovatum was identified, and then identified again on repeated cultures. Subsequently, Natacin was administered every two hours. Amniotic membrane transplantation was performed due to a persistent epithelial defect and impending corneal perforation. Three weeks after amniotic membrane transplantation, the epithelial defect had completely healed, but the cornea had turned opaque. Six months after amniotic membrane transplantation, visual acuity was light perception only, and corneal thinning and diffuse corneal opacification remained opaque. Six months after amniotic membrane transplantation, visual acuity was light perception only, and corneal thinning and diffuse corneal opacification remained.

A Case of Acute Myeloid Leukemia Transformed from JAK2 V617F-Positive Chronic Neutrophilic Leukemia

Chronic neutrophilic leukemia (CNL) is a rare myeloproliferative neoplasm (MPN) characterized by persistent peripheral blood neutorphilia, bone marrow hypercellularity of neutrophilic granulocyte proliferation and hepatosplenomegaly. Acquired somatic mutation, JAK2 V617F, is the only molecular marker known to have association with classic BCR-ABL1 negative MPNs. However, JAK2 V617F has been detected occasionally in other MPNs such as CNL or other disease entities. We experienced a case of CNL with JAK2 V617F mutation. The patient was diagnosed according to the 2008 WHO classification criteria, and developed AML 9 months after the diagnosis of CNL. The JAK2 V617F was detected in the bone marrow throughout the clinical course. More cases are needed to establish the role of JAK2 V617F in the pathogenesis, prognosis and disease course of CNL.

Number of Blood Cultures per 1,000 Patient Days at University-Affiliated Hospitals in Korea / 대한임상미생물학회지

The authors calculated the number of blood cultures per 1,000 admitted patient days at seven university-affiliated hospitals in 2010, which ranged from 65 to 129 (mean 110). The number of blood cultures per 1,000 patient days could possibly be a good parameter for assessing the appropriateness of blood culture.

Comprehensive Analysis of Blood Culture Performed at Nine University Hospitals in Korea / 대한진단검사의학회지

BACKGROUND: Optimal blood culture performance is critical for successful diagnosis and treatment of sepsis. To understand the status of blood culture, we investigated several aspects of the procedure at 9 university hospitals. METHODS: The process of ordering blood culture sets and sampling volume for adults and children was investigated from January 2010 to April 2010, while the positive rate of detection and growth of skin contaminants were compared in 2009. Microbial growth in aerobic and anaerobic bottles was investigated prospectively. RESULTS: A majority of the hospitals used 2 sets of bottles for adults and 1 bottle for children. The average blood volume in each set was 7.7 mL for adults and 2.1 mL for children. The positive rate of microorganisms was 8.0%, and the isolation rate of the normal flora of the skin was 2.1%. Bacterial growth rates in aerobic and anaerobic bottles only were 31.8% and 24.5% respectively. CONCLUSIONS: Ordering blood culture sets and sampling volumes did not comply with CLSI guidelines. However, the rate of positive cultures and skin contamination rates were acceptable. Anaerobic bottles are useful in enhancing the yield of microorganisms.