Sudden Deaths of Neonates Receiving Intravenous Infusion of Lipid Emulsion Contaminated with Citrobacter freundii.

At an intensive care unit, four neonates died consecutively within 80 minutes. Citrobacter freundii was isolated from blood samples of the 4 patients. It was also cultured from the leftover SMOFlipid that had been infused intravenously into the patients. In this in vitro study, we evaluated the bacterial growth kinetics and change in size of fat globules in SMOFlipid contaminated with C. freundii. Following the growth of bacteria, pH of SMOFlipid decreased to < 6, and the number of fat globules larger than 5 µm increased. Pulmonary fat embolism is proposed as a possible cause of the sudden deaths as well as fulminant sepsis.

Microevolution of Outbreak-Associated Middle East Respiratory Syndrome Coronavirus, South Korea, 2015.

During the 2015 Middle East respiratory syndrome coronavirus outbreak in South Korea, we sequenced full viral genomes of strains isolated from 4 patients early and late during infection. Patients represented at least 4 generations of transmission. We found no evidence of changes in the evolutionary rate and no reason to suspect adaptive changes in viral proteins.

Serotype Distribution and Antimicrobial Susceptibilities of Invasive Streptococcus pneumoniae Isolates from Adults in Korea from 1997 to 2012.

In Republic of Korea, a 7-valent pneumococcal conjugated vaccine (PCV7) was licensed for use in infants in 2003, and 13-valent PCV (PCV13) replaced it since 2010. We investigated trends in serotype distribution and antibiotic susceptibility of pneumococcal isolates from adult patients with invasive pneumococcal diseases (IPD). Invasive pneumococcal isolates from adult patients of ≥ 16 years of age were collected from 1997 to 2012. Serotypes of the isolates were determined by the Quellung reaction. Distribution of serotypes was analyzed according to the vaccine types. Antibiotic susceptibility was tested by using E-test strips. A total of 272 invasive pneumococcal isolates were included. The most common serotypes were serotype 19F (8.5%, 23/272), and serotype 3 (8.1%, 22/272), and 24.6% (67/272) of the isolates were of non-vaccine serotypes. Of the 272 isolates, 2.6% (7/272) were penicillin MICs of ≥ 4 µg/mL. The proportion of the PCV13 serotypes decreased from 63.3% (50/79) in 1997-2003 to 48.6% (17/35) in 2011-2012, whereas that of non-vaccine serotypes was 26.6% (21/79) and 25.7% (9/35), respectively, for the same periods. The proportion of the PCV13 serotypes showed a decreasing trend among adult patients with IPD over the study period.

Inappropriate continued empirical vancomycin use in a hospital with a high prevalence of methicillin-resistant Staphylococcus aureus.

Vancomycin is frequently inappropriately prescribed, especially as empirical treatment. The aim of this study was to evaluate (i) the amount of inappropriate continued empirical vancomycin use as a proportion of total vancomycin use and (ii) the risk factors associated with inappropriate continued empirical vancomycin use. We reviewed the medical records of adult patients who had been prescribed at least one dose of parenterally administered vancomycin between January and June 2012, in a single tertiary care hospital. When empirically prescribed vancomycin treatment was continued after 96 h without documentation of beta-lactam-resistant Gram-positive microorganisms in clinical specimens with significance, the continuation was considered inappropriate, and the amount used thereafter was considered inappropriately used. We identified risk factors associated with inappropriate continued empirical vancomycin use by multiple logistic regression. During the study period, the amount of parenterally administered vancomycin prescribed was 34.2 defined daily doses (DDDs)/1,000 patient-days (1,084 prescriptions for 971 patients). The amount of inappropriate continued empirical vancomycin use was 8.5 DDDs/1,000 patient-days, which represented 24.9% of the total parenterally administered vancomycin used (8.5/34.2 DDDs/1,000 patient-days). By multivariate analyses, inappropriate continued empirical vancomycin use was independently associated with the absence of any documented etiological organism (adjusted odds ratio [aOR], 1.60 [95% confidence interval {CI}, 1.06 to 2.41]) and suspected central nervous system (CNS) infections (aHR, 2.33 [95% CI, 1.20 to 4.50]). Higher Charlson's comorbidity index scores were inversely associated with inappropriate continued empirical vancomycin use (aHR, 0.90 [95% CI, 0.85 to 0.97]). Inappropriate continued empirical vancomycin use represented 24.9% of the total amount of vancomycin prescribed, which indicates room for improvement.

Frequency and clinical implications of the isolation of rare nontuberculous mycobacteria.

BACKGROUND: To date, more than 125 species of nontuberculous mycobacteria (NTM) have been identified. In this study, we investigated the frequency and clinical implication of the rarely isolated NTM from respiratory specimens. METHODS: Patients with NTM isolated from their respiratory specimens between July 1, 2010 and June 31, 2012 were screened for inclusion. Rare NTM were defined as those NTM not falling within the group of eight NTM species commonly identified at our institution: Mycobacterium avium, M. intracellulare, M. abscessus, M. massiliense, M. fortuitum, M. kansasii, M. gordonae, and M. peregrinum. Clinical, radiographic and microbiological data from patients with rare NTM were reviewed and analyzed. RESULTS: During the study period, 73 rare NTM were isolated from the respiratory specimens of 68 patients. Among these, M. conceptionense was the most common (nine patients, 12.3%). The median age of the 68 patients with rare NTM was 68 years, while 39 of the patients were male. Rare NTM were isolated only once in majority of patient (64 patients, 94.1%). Among the four patients from whom rare NTM were isolated two or more times, only two showed radiographic aggravation caused by rare NTM during the follow-up period. CONCLUSIONS: Most of the rarely identified NTM species were isolated from respiratory specimens only once per patient, without concomitant clinical aggravation. Clinicians could therefore observe such patients closely without invasive work-ups or treatment, provided the patients do not have decreased host immunity towards mycobacteria.

Direct identification of Gram-positive bacteria and resistance determinants from blood cultures using a microarray-based nucleic acid assay: in-depth analysis of microarray data for undetermined results.

BACKGROUND: The Verigene Gram-Positive Blood Culture (BC-GP) nucleic acid assay (Nanosphere, Inc., Northbrook, IL, USA) is a newly developed microarray-based test with which 12 Gram-positive bacterial genes and three resistance determinants can be detected using blood culture broths. We evaluated the performance of this assay and investigated the signal characteristics of the microarray images. METHODS: At the evaluation stage, we tested 80 blood cultures that were positive for various bacteria (68 bacteria covered and 12 not covered by the BC-GP panel) collected from the blood of 36 patients and 44 spiked samples. In instances where the automated system failed and errors were called, we manually inspected microarray images, measured the signal intensities of target spots, and reclassified the results. RESULTS: With the manual analysis of the microarray images of 14 samples for which error calls were reported, we could obtain correct identification results for 12 samples without the need for retesting, because strong signals in the target spots were clearly discriminable from background noise. With our interpretation strategy, we could obtain 97.1% sensitivity and 100% specificity for bacterial identification by using the BC-GP assay. The two unidentified bacteria were viridans group streptococci, which produced weaker target signals. During the application stage, among 25 consecutive samples positive for Gram-positive bacteria, we identified two specimens with error calls as Streptococcus spp. by using manual analysis. CONCLUSIONS: With help of the manual review of the microarray images, the BC-GP assay could successfully identify species and resistance markers for many clinically important Gram-positive bacteria.

Setting the Gray Zone of Near-Cutoff Values in a Real-Time PCR Test for the Detection of Mycobacterium tuberculosis in an Intermediate Burden Country.

BACKGROUND: Recently, molecular detection of Mycobacterium tuberculosis in a respiratory specimens is accepted as one of the standard procedures for diagnosis of tuberculosis in Korea. When detecting tuberculosis using a real-time polymerase chain reaction (PCR), results showed the repeated near-cutoff values in a specimen make it difficult for the laboratory to give definitive reports as positive or negative. METHODS: We retrospectively evaluated clinical state of ninety-eight patients who were not currently taking antituberculosis medications and had near-cutoff values of respiratory specimens using a real-time PCR test. RESULTS: Sixty-eight percent of the patients had clinical tuberculosis. In subgroup analysis, patients less than the age of 50, 94.3% had tuberculosis while only 55.6% of the patients with the age of equal and over 50 had tuberculosis (p < 0.001). CONCLUSIONS: Setting a gray zone for real-time PCR result and give additional tailored information onto the interpretative report would be suggested for the clinical practice in an intermediate burden of tuberculosis country.

Comparison of xTAG respiratory virus panel and Verigene Respiratory Virus Plus for detecting influenza virus and respiratory syncytial virus.

BACKGROUND: Nucleic acid amplification tests have allowed simultaneous detection of multiple respiratory viruses. METHODS: We compared the results of a liquid bead array xTAG Respiratory Virus Panel (RVP; (Luminex Corporation, Toronto, Canada) and a solid microarray Verigene Respiratory Virus Plus (RV+; Nanosphere, Northbrook, IL) for the detection of influenza A virus (INF A), influenza B virus (INF B), and respiratory syncytial virus (RSV) in 170 respiratory specimens from hospitalized patients. RESULTS: Overall, xTAG RVP demonstrated sensitivities and specificities of 97.6 and 100% for INF A, 100 and 99.4% for INF B, and 100 and 100% for RSV, while the Verigene RV+ test sensitivities and specificities were 95.1 and 98.5%, 100.0 and 99.4%, and 97.1 and 100%, respectively. There were no significant differences in the area under the curves between the two assays for each virus (P = 0.364 for INF A, P = 1.000 for INF B, P = 0.317 for RSV). Comparing the results of two assays, discordant results were present mostly due to subtype assignments and identification of coinfections. The detection of viruses was not significantly different (P = 1.000) and the virus/subtype assignment showed good agreement with kappa coefficients of 0.908. CONCLUSION: The xTAG RVP and Verigene RV+ showed high sensitivities and specificities, and good overall agreement in detection and identification of INF and RSV. These assays can be used in clinical settings for a reliable detection of respiratory viruses found commonly in hospitalized patients.

Diagnostic value of direct fluorescence antibody staining for detecting Pneumocystis jirovecii in expectorated sputum from patients with HIV infection.

Direct fluorescent antibody (DFA) staining of induced sputum is frequently used to diagnose Pneumocystis pneumonia (PCP) in patients infected with human immunodeficiency virus, although induction can provoke nausea and bronchospasm. Since the diagnostic value of expectorated sputum examined with DFA stain has not been well evaluated, we reviewed the medical records of HIV-infected patients who were clinically diagnosed as having PCP between 1999 and 2011. Over this 13-year period, we found 76 patients whose records included the results of DFA staining of expectorated sputum and noted that 42 (55.3%) were positive. Polymerase chain reaction to detect Pneumocystis in the sputum of 65 of the patients resulted in the finding of 43 (66.2%) who were positive. Our findings suggest that DFA staining of expectorated sputum could be a useful initial diagnostic method in HIV-infected patients with PCP.

Can a routine follow-up blood culture be justified in Klebsiella pneumoniae bacteremia? A retrospective case-control study.

BACKGROUND: The need for mandatory confirmation of negative conversion in Klebsiella pneumoniae bacteremia (KpB) has not been adequately addressed. We conducted a retrospective case-control study of adult patients with KpB over a 5-year period in two tertiary-care hospitals to determine the risk factors for persistent bacteremia and to reevaluate the necessity of follow-up blood culture in KpB. METHODS: Persistent KpB is defined as the finding of K. pneumoniae in more than two separate blood-culture samples for longer than a two-day period in a single episode. The case- and control-groups were patients with persistent and non-persistent KpB, respectively, and they were matched 1-to-3 according to age and gender. RESULTS: Among 1068 KpB episodes analyzed after excluding polymicrobial infection and repeated KpB, follow-up blood cultures were performed in 862 cases (80.7%), 62 of which (7.2%) were persistent. Independent risk factors for persistence were intra-abdominal infection, higher Charlson's comorbidity weighted index score, prior solid organ transplantation, and unfavorable treatment response, which was defined as positivity for at least two parameters among fever, leukocytosis, and no decrease of C-reactive protein on the second day after initial culture. A proposed scoring system using four variables, namely, intra-abdominal infection, nosocomial KpB, fever and lack of C-reactive protein decrease, the last two being assessed on the second day after the initial blood culture, showed that only 4.9% of the patients with no risk factors or with only intra-abdominal infection had persistent KpB. CONCLUSIONS: Though persistent KpB is uncommon, follow-up blood culture was performed in as many as 80% of the cases in this study. A more careful clinical assessment is warranted to reduce the cost and patient inconvenience involved in follow-up blood culture.

Clinical and radiological features of invasive Klebsiella pneumoniae liver abscess syndrome.

BACKGROUND: Recently, a striking new clinical manifestation of Klebsiella pneumoniae (KP) infection referred to as invasive KP liver abscess syndrome (IKPLAS), defined by liver abscess with contemporaneous metastatic KP infections at other body sites has been documented. Until now, however, there have been relatively few reports regarding its radiologic features. PURPOSE: To describe the clinical and radiological features of IKPLAS patients, and to compare them with those with KP liver abscess without metastatic infections to ascertain possible predictors of IKPLAS. MATERIAL AND METHODS: From January 2008 to May 2010, 35 patients (26 men and 9 women; mean age, 59.4 years) with both liver abscess and metastatic KP infections were diagnosed with IKPLAS. Their clinical and radiological features were retrospectively evaluated and compared with those of 25 contemporaneous non-metastatic patients to investigate predictive factors for metastatic infections. RESULTS: The rate of intensive care unit admissions and overall mortality was 34.3% and 17.1% in IKPLAS patients, and was significantly higher than those of the non-metastatic group (8% and 0%, respectively). As for metastatic infections, the lung was the most common site and multiple nodules or masses (n = 9) were the most common manifestations. Univariate analysis revealed that liver abscess ≤5.8 cm, bilobar involvement of abscess and altered mentality were significantly related with IKPLAS. At multivariate analysis, liver abscess ≤5.8 cm was proven to be a significant independent predictor of IKPLAS (OR, 3.6; P = 0.038). In addition, altered mentality was present solely in IKPLAS (25.7% vs. 0%) although its P value (P = 0.052) did not reach a statistical significance at multivariate analysis. CONCLUSION: IKPLAS has significantly worse prognosis than non-metastatic KP abscess patients. In patients with KP liver abscess, liver abscess ≤5.8 cm can be used as an independent predictor of IKPLAS and altered mentality as a very specific feature in diagnosing IKPLAS.

Evaluation of two hepatitis C virus genotyping assays based on the 5' untranslated region (UTR): the limitations of 5' UTR-based assays and the need for a supplementary sequencing-based approach.

We evaluated two genotyping methodologies that characterize the 5' untranslated region (5' UTR) of the hepatitis C virus (HCV) genome. The limitations of these genotype assays need to be thoroughly evaluated, and sequencing-based approaches may be needed to complement these methods in clinical settings.

Elevated post-transfusion serum transaminase values associated with a highly significant trend for increasing prevalence of anti-Vesivirus antibody in Korean patients.

A highly significant increase in anti-Vesivirus (family Caliciviridae) antibody prevalence, along the axis from healthy blood donors; donors with elevated transaminase; patients with clinical hepatitis; and patients with post-transfusion/dialysis hepatitis, has been reported in human sera from the USA and Europe. Asian samples have now been tested retrospectively using serology and enzyme immunoassay (EIA) with a Vesivirus partial-capsid antigen expressed as a fusion protein. Anti-vesiviral antibodies were measured by optical densities (OD(650)) and compared in patients separated by age, gender and Groups A-F as follows: Control Group A, an Experimental Group B, which was divided further into Group C, patients with elevated enzymes (alanine transaminase (ALT), aspartate transaminase (AST), and γ-glutamyl transpeptidase (γ-GT); Group D, patients receiving transfused blood; Group E, patients with high enzyme levels after transfusion; and Group F, hepatitis B and C positive patients. Using multivariate logistic regression analyses, a significantly greater proportion of patients receiving transfusion(s), were positive for anti-Vesivirus antibody compared with non-transfused patients (P = 0.008; OR: 3.86, 95% CI: 1.43-10.43). Also, anti-Vesivirus antibody was significantly associated with elevated biochemical liver function tests: ALT ≥ 20 IU or AST ≥ 120 IU (P = 0.017; OR: 4.23, 95% CI: 1.30-13.80). In the blood transfusion group, anti-Vesivirus antibody was significantly correlated with high enzyme levels (ALT, P = 0.018; AST, P = 0.010; γ-GT, P = 0.020). These data provide serologic evidence of vesiviral transfusion-transmission-associated disease, which could include infection of any organ system where cytopathology resulted in high levels of either ALT or AST.

Differences in characteristics between healthcare-associated and community-acquired infection in community-onset Klebsiella pneumoniae bloodstream infection in Korea.

BACKGROUND: Healthcare-associated (HCA) infection has emerged as a new epidemiological category. The aim of this study was to evaluate the impact of HCA infection on mortality in community-onset Klebsiella pneumoniae bloodstream infection (KpBSI). METHODS: We conducted a retrospective study in two tertiary-care hospitals over a 6-year period. All adult patients with KpBSI within 48 hours of admission were enrolled. We compared the clinical characteristics of HCA and community-acquired (CA) infection, and analyzed risk factors for mortality in patients with community-onset KpBSI. RESULTS: Of 553 patients with community-onset KpBSI, 313 (57%) were classified as HCA- KpBSI and 240 (43%) as CA-KpBSI. In patients with HCA-KpBSI, the severity of the underlying diseases was higher than in patients with CA-KpBSI. Overall the most common site of infection was the pancreatobiliary tract. Liver abscess was more common in CA-KpBSI, whereas peritonitis and primary bacteremia were more common in HCA-KpBSI. Isolates not susceptible to extended-spectrum cephalosporin were more common in HCA- KpBSI than in CA-KpBSI (9% [29/313] vs. 3% [8/240]; p = 0.006). Overall 30-day mortality rate was significantly higher in HCA-KpBSI than in CA-KpBSI (22% [70/313] vs. 11% [27/240]; p = 0.001). In multivariate analysis, high Charlson's weighted index of co-morbidity, high Pitt bacteremia score, neutropenia, polymicrobial infection and inappropriate empirical antimicrobial therapy were significant risk factors for 30-day mortality. CONCLUSIONS: HCA-KpBSI in community-onset KpBSI has distinctive characteristics and has a poorer prognosis than CA-KpBSI, but HCA infection was not an independent risk factor for 30-day mortality.

Effect of routine sterile gloving on contamination rates in blood culture: a cluster randomized trial.

BACKGROUND: Blood culture contamination leads to inappropriate or unnecessary antibiotic use. However, practical guidelines are inconsistent about the routine use of sterile gloving in collection of blood for culture. OBJECTIVE: To determine whether the routine use of sterile gloving before venipuncture reduces blood culture contamination rates. DESIGN: Cluster randomized, assessor-blinded, crossover trial (ClinicalTrials.gov registration number: NCT00973063). SETTING: Single-center trial involving medical wards and the intensive care unit. PARTICIPANTS: 64 interns in charge of collection of blood for culture were randomly assigned to routine-to-optional or optional-to-routine sterile gloving groups for 1854 adult patients who needed blood cultures. INTERVENTION: During routine sterile gloving, the interns wore sterile gloves every time before venipuncture, but during optional sterile gloving, sterile gloves were worn only if needed. MEASUREMENTS: Isolates from single positive blood cultures were classified as likely contaminant, possible contaminant, or true pathogen. Contamination rates were compared by using generalized mixed models. RESULTS: A total of 10 520 blood cultures were analyzed: 5265 from the routine sterile gloving period and 5255 from the optional sterile gloving period. When possible contaminants were included, the contamination rate was 0.6% in routine sterile gloving and 1.1% in optional sterile gloving (adjusted odds ratio, 0.57 [95% CI, 0.37 to 0.87]; P = 0.009). When only likely contaminants were included, the contamination rate was 0.5% in routine sterile gloving and 0.9% in optional sterile gloving (adjusted odds ratio, 0.51 [CI, 0.31 to 0.83]; P = 0.007). LIMITATION: Blood cultures from the emergency department, surgical wards, and pediatric wards were not assessed. CONCLUSION: Routine sterile gloving before venipuncture may reduce blood culture contamination.

Is cefazolin inferior to nafcillin for treatment of methicillin-susceptible Staphylococcus aureus bacteremia?

About 20% of methicillin-susceptible Staphylococcus aureus (MSSA) isolates have a substantial inoculum effect with cefazolin, suggesting that cefazolin treatment may be associated with clinical failure for serious MSSA infections. There are no well-matched controlled studies comparing cefazolin with nafcillin for the treatment of MSSA bacteremia. A retrospective propensity-score-matched case-control study was performed from 2004 to 2009 in a tertiary care hospital where nafcillin was unavailable from August 2004 to August 2006. The cefazolin group (n = 49) included MSSA-bacteremic patients treated with cefazolin during the period of nafcillin unavailability, while the nafcillin group (n = 84) comprised those treated with nafcillin. Treatment failure was defined as a composite outcome of a change of antibiotics due to clinical failure, relapse, and mortality. Of 133 patients, 41 patients from each group were matched by propensity scores. There were no significant differences in baseline characteristics between the matched groups. The treatment failure rates were not significantly different at 4 or 12 weeks (10% [4/41] versus 10% [4/41] at 4 weeks [P > 0.99] and 15% [6/41] versus 15% [6/41] at 12 weeks [P > 0.99]). Cefazolin treatment was interrupted less frequently than nafcillin treatment due to drug adverse events (0% versus 17%; P = 0.02). Cefazolin had clinical efficacy similar to that of nafcillin and was more tolerable than nafcillin for the treatment of MSSA bacteremia.

Tuf gene sequence analysis has greater discriminatory power than 16S rRNA sequence analysis in identification of clinical isolates of coagulase-negative staphylococci.

We compared and analyzed 16S rRNA and tuf gene sequences for 97 clinical isolates of coagulase-negative staphylococci (CNS) by use of the GenBank, MicroSeq, EzTaxon, and BIBI databases. Discordant results for definitive identification were observed and differed according to the different databases and target genes. Although higher percentages of sequence identity were obtained with GenBank and MicroSeq for 16S rRNA analysis, the BIBI and EzTaxon databases produced less ambiguous results. Greater discriminatory power and fewer multiple probable identifications were observed with tuf gene analysis than with 16S rRNA analysis. The most pertinent results for tuf gene analysis were obtained with the GenBank database when the cutoff values for the percentage of identity were adjusted to be greater than or equal to 98.0%, with >0.8% separation between species. Analysis of the tuf gene proved to be more discriminative for certain CNS species; further, this method exhibited better distinction in the identification of CNS clinical isolates.

Usefulness of three-channel multiplex real-time PCR and melting curve analysis for simultaneous detection and identification of the Mycobacterium tuberculosis complex and nontuberculous mycobacteria.

We attempted to determine the benefits of three-channel multiplex real-time PCR and melting curve analysis not only in detecting and distinguishing between nontuberculous mycobacteria (NTM) and the Mycobacterium tuberculosis complex but also in identifying NTM to the species level.