Inoculum effect of methicillin-susceptible Staphylococcus aureus against broad-spectrum beta-lactam antibiotics

Scarce information concerning the inoculum effect (InE) of methicillin-susceptible Staphylococcus aureus (MSSA) against broad-spectrum β-lactam antibiotics is available. We investigated the InE of MSSA against ceftriaxone, cefepime, meropenem, ampicillin/sulbactam and piperacillin/tazobactam. The bacteraemic MSSA isolates were collected at ten Korean general hospitals from Sep 2013 to Mar 2015. The InE was defined if MICs of antibiotics at high inoculum (HI, ~5 × 10⁷ CFU/ml) increased beyond the susceptible range compared to those at standard inoculum (SI, ~5 × 10⁵ CFU/ml). All isolates were sequenced for blaZ gene typing. Among 302 MSSA isolates, 254 (84.1%) were positive for blaZ; types A, B, C and D were 13.6%, 26.8%, 43.4% and 0.3%, respectively. Mean HI MICs of all tested antibiotics were significantly increased and increases in HI MIC of piperacillin/tazobactam (HI, 48.14 ± 4.08 vs. SI, 2.04 ± 0.08 mg/L, p < 0.001) and ampicillin/sulbactam (HI, 24.15 ± 1.27 vs. SI, 2.79 ± 0.11 mg/L, p < 0.001) were most prominent. No MSSA isolates exhibited meropenem InE, and few isolates exhibited cefepime (0.3%) and ceftriaxone (2.3%) InE, whereas 43.0% and 65.9% of MSSA isolates exhibited piperacillin/tazobactam and ampicillin/sulbactam InE, respectively. About 93% of type C blaZ versus 45% of non-type C exhibited ampicillin/sulbactam InE (p < 0.001) and 88% of type C blaZ versus 9% of non-type C exhibited piperacillin/tazobactam InE (p < 0.001). A large proportion of MSSA clinical isolates, especially those positive for type C blaZ, showed marked ampicillin/sulbactam InE and piperacillin/tazobactam.

Risk factors for poor outcome in community-onset Clostridium difficile infection

Background

A substantial portion of Clostridium difficile infection (CDI) cases occur in communities, and community-onset CDI (CO-CDI) can lead to serious complications including mortality. This study aimed to identify the risk factors for a poor outcome in CO-CDI.

Methods

We performed a retrospective review of all inpatients with CDI, in a 1300-bed tertiary-care hospital in Korea, from 2008 through 2015. CO-CDI was defined as CDI occurring within 48 h of admission. Poor outcome was defined as follows: 1) all-cause 30-day mortality, 2) in-hospital mortality, or 3) surgery due to CDI.

Results

Of a total 1256 CDIs occurring over 8 years, 152 (12.1%) cases were classified as CO-CDI and 23 (15.1%) had a poor outcome, including 22 (14.5%) cases of mortality and 2 (1.3%) cases of surgery. Patients with a poor outcome had a higher mean age than those without a poor outcome (75.8 vs. 69.6 years, p = 0.03). The proportion of men and prior proton pump inhibitor (PPI) use were significantly higher in the poor outcome group (65.2% vs. 41.9%, p = 0.04; 39.1% vs. 17.6%, p = 0.02, respectively). Multivariate binary logistic model showed that PPI use and anemia (hemoglobin < 10 g/dL) at presentation were significantly associated with a poor outcome (adjusted odds ratio [aOR], 3.76; 95% confidence interval [95CI], 1.26-11.21, aOR, 4.67; 95CI, 1.52-14.34, respectively).

Conclusions

Clinicians should not only be aware of the possibility of CDI in the community setting but also pay more attention to PPI-using elderly patients with anemia in consideration of a poor outcome.

Replicative virus shedding in the respiratory tract of patients with Middle East respiratory syndrome coronavirus infection

•

Middle East respiratory syndrome coronavirus (MERS-CoV) sub-genomic mRNAs indicates that the virus is replicative.

•

Sub-genomic mRNA was detected in lower respiratory tract specimens for up to 4 weeks after symptoms developed.

•

In upper respiratory tract specimens, the detection of sub-genomic mRNA and genomic RNA did not correlate.

Background

Information on the duration of replicative Middle East respiratory syndrome coronavirus (MERS-CoV) shedding is important for infection control. The detection of MERS-CoV sub-genomic mRNAs indicates that the virus is replicative. This study examined the duration for detecting MERS-CoV sub-genomic mRNA compared with genomic RNA in diverse respiratory specimens.

Methods

Upper and lower respiratory samples were obtained from 17 MERS-CoV-infected patients. MERS-CoV sub-genomic mRNA was detected by reverse transcription PCR (RT-PCR) and MERS-CoV genomic RNA by real-time RT-PCR.

Results

In sputum and transtracheal aspirate, sub-genomic mRNA was detected for up to 4 weeks after symptoms developed, which correlated with the detection of genomic RNA. In oropharyngeal and nasopharyngeal swab specimens, the detection of sub-genomic mRNA and genomic RNA did not correlate.

Conclusions

These findings suggest that MERS-CoV does not replicate well in the upper respiratory tract.

Effect of an intervention targeting inappropriate continued empirical parenteral vancomycin use: a quasi-experimental study in a region of high MRSA prevalence

Background

Despite vancomycin use is a major risk factor for the emergence of vancomycin resistance, it is frequently inappropriately prescribed, especially as empirical treatment. We evaluated the effect of an antimicrobial stewardship intervention targeting for inappropriate continued empirical vancomycin use.

Methods

This was a quasi-experimental study comparing vancomycin use in a 6-month pre-intervention and 6-month intervention period. If empirical vancomycin was continued for more than 96 h without documentation of beta-lactam-resistant gram-positive microorganisms, it was considered inappropriate continued empirical vancomycin use. The intervention consisted of the monitoring of appropriateness by a pharmacist and direct discussion with the prescribing physicians by infectious disease specialists when empirical vancomycin was continued inappropriately. An interrupted time series analysis was used to compare vancomycin use before and during the intervention.

Results

Following implementation of the intervention, overall vancomycin consumption decreased by 14.6%, from 37.6 defined daily doses (DDDs)/1000 patient-days in the pre-intervention period to 32.1 DDDs/1000 patient-days in the intervention period (P <  0.001). The inappropriate consumption of vancomycin also declined from 8.0 DDDs/1000 patient-days to 5.8 DDDs/1000 patient-days (P = 0.009).

Conclusion

Interventions such as direct communication with prescribing physicians and infectious disease clinicians can help reduce the inappropriate continued use of vancomycin.

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.

Middle East respiratory syndrome: what we learned from the 2015 outbreak in the Republic of Korea

Middle East Respiratory Syndrome coronavirus (MERS-CoV) was first isolated from a patient with severe pneumonia in 2012. The 2015 Korea outbreak of MERSCoV involved 186 cases, including 38 fatalities. A total of 83% of transmission events were due to five superspreaders, and 44% of the 186 MERS cases were the patients who had been exposed in nosocomial transmission at 16 hospitals. The epidemic lasted for 2 months and the government quarantined 16,993 individuals for 14 days to control the outbreak. This outbreak provides a unique opportunity to fill the gap in our knowledge of MERS-CoV infection. Therefore, in this paper, we review the literature on epidemiology, virology, clinical features, and prevention of MERS-CoV, which were acquired from the 2015 Korea outbreak of MERSCoV.

Active surveillance for carbapenem-resistant Enterobacteriaceae, vancomycin-resistant enterococci and toxigenic Clostridium difficile among patients transferred from long-term care facilities in Korea

A 10-month active surveillance study was conducted to assess carriage of carbapenemase-producing Enterobacteriaceae (CPE), vancomycin-resistant enterococci (VRE) and toxigenic Clostridium difficile colonization among patients transferred to hospital from long-term care facilities (LTCFs). Four (1.4%) patients with carbapenem-resistant Enterobacteriaceae (none of which were CPE), 59 (21%) patients with VRE and 20 (7.1%) patients colonized with toxigenic C. difficile were identified from 282 rectal specimens. There was no outbreak of VRE infection during the study period. The low prevalence of CPE carriage suggests that screening all admissions from LTCFs for CPE would not be cost-effective, and that screening and use of contact precautions for VRE should be reconsidered.

The limited role of serum galactomannan assay in screening for invasive pulmonary aspergillosis in allogeneic stem cell transplantation recipients on micafungin prophylaxis: a retrospective study

Background

We evaluated the outcomes of serum galactomannan (GM) assay for the screening of invasive pulmonary aspergillosis (IPA) in allogeneic hematopoietic stem cell transplantation (alloHSCT) recipients while on primary antifungal prophylaxis (PAP).

Methods

This study included patients with hematologic disorders who underwent alloHSCT from January 2013 to November 2015. Patients received routine PAP with fluconazole before 2014 and micafungin after 2014; serum GM tests were performed and retrospectively analyzed. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of serum GM tests for detection of probable/proven IPA were evaluated. The serial change of serum GM levels was illustrated on a time series plot.

Results

A total of 136 alloHSCT recipients at Seoul National University Hospital were included in the study. Fluconazole was administered in 72 patients for PAP, while micafungin was administered in the remaining 64 patients. The overall sensitivity, specificity, and NPV of serum GM assays were 95.8% (95% confidence interval [CI] 78.9–99.9%), 93.8% (95% CI 91.7–95.5%), and 99.8% (95% CI 99.1–100.0%), respectively. However, the PPV of GM tests was relatively low at 35.4% (95% CI 23.9–48.2%). The serial change in serum GM levels differed according to the antifungal agents used. With effective PAP using micafungin, serial serum GM levels showed zero order kinetics during the neutropenic period.

Conclusion

Although the serum GM assay is a sensitive and specific test for detecting IPA in alloHSCT recipients, its role for routine surveillance in an era of effective PAP with micafungin is limited.

MERS-CoV Antibody Responses 1 Year after Symptom Onset, South Korea, 2015

We investigated the kinetics of the Middle East respiratory syndrome coronavirus (MERS-CoV) neutralizing and spike protein antibody titers over the course of 1 year in 11 patients who were confirmed by reverse transcription PCR to have been infected during the outbreak in South Korea in 2015. Robust antibody responses were detected in all survivors who had severe disease; responses remained detectable, albeit with some waning, for <1 year. The duration of viral RNA detection (but not viral load) in sputum significantly correlated with the antibody response magnitude. The MERS S1 ELISA antibody titers correlated well with the neutralizing antibody response. Antibody titers in 4 of 6 patients who had mild illness were undetectable even though most had evidence of pneumonia. This finding implies that MERS-CoV seroepidemiologic studies markedly underestimate the extent of mild and asymptomatic infection. Obtaining convalescent-phase plasma with high antibody titers to treat MERS will be challenging.

In vitro antiviral activity of ribavirin against severe fever with thrombocytopenia syndrome virus

BACKGROUND/AIMS

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by severe fever with thrombocytopenia syndrome virus (SFTSV), a novel bunyavirus. As yet, there is no effective antiviral therapy for SFTS. Ribavirin is a broad-spectrum antiviral agent, which has been tried for treatment of SFTS. In this study, antiviral activity of ribavirin against SFTSV has been investigated.

METHODS

Vero cell-grown SFTSV strain Gangwon/Korea/2012 was treated with ribavirin at various concentrations. Antiviral activity of ribavirin was evaluated by inhibition of the SFTSV cytopathic effect in Vero cells and quantification of viral RNA load in culture supernatant using one-step real-time reverse transcription polymerase chain reaction. Cytotoxicity of ribavirin was determined by a tetrazolium-based colorimetric method.

RESULTS

Ribavirin reduced SFTSV titers in a dose-dependent manner, with a half-maximal inhibitory concentration ranged from 3.69 to 8.72 μg/mL. Cytopathic effects were reduced as ribavirin concentration increased. No significant cytotoxicity was detected at ribavirin concentrations of ≤ 31.3 μg/mL.

CONCLUSIONS

Ribavirin exhibited inhibitory activity against SFTSV replication in vitro, which suggests that ribavirin can be used as a potential antiviral agent for SFTS.

agr functionality affects clinical outcomes in patients with persistent methicillin-resistant Staphylococcus aureus bacteraemia

Methicillin-resistant Staphylococcus aureus bacteremia (MRSAB) often persists despite appropriate antibiotic therapy. It is unclear what microbiological factors contribute to poor clinical outcomes in persistent MRSAB (pMRSAB). We aimed to identify clinical and microbiological risk factors for in-hospital mortality in pMRSAB. We analysed MRSAB cases prospectively collected between 2009 and 2016 at 11 hospitals in Korea, defining cases of pMRSAB as MRSAB lasting ≥5 days despite administration of effective antibiotics. The first blood isolates from the pMRSAB cases were tested for staphylococcal cassette chromosome mec type, staphylococcal protein A type, accessary gene regulator (agr) type, genes for Panton-Valentine leukocidin and phenol-soluble modulin-mec, vancomycin minimum inhibitory concentration, vancomycin heteroresistance, and agr functionality. We also collected clinical information for each case. Of 960 MRSAB cases, 152 pMRSAB were finally eligible. Univariable analysis revealed that in-hospital mortality was significantly associated with Charlson's comorbidity-weighted index (CCWI) score, Pitt bacteremia score, sequential organ failure assessment score, presentation with septic shock, pneumonia, agr dysfunction, and vancomycin heteroresistance. Bone and joint infections were negatively associated with in-hospital mortality. Multivariable analysis revealed the following independent risk factors for in-hospital mortality: CCWI score [adjusted odds ratio (aOR), per one point, 1.25; 95% confidence interval (CI), 1.08-1.44; P = 0.003), Pitt bacteremia score (aOR, per one point, 1.33; 95% CI, 1.09-1.62; P = 0.005), non-eradicated foci of infection (aOR, 3.12; 95% CI, 1.18-8.27; P = 0.022), and agr dysfunction (aOR, 2.48; 95% CI, 1.12-5.47; P = 0.025). agr dysfunction is an independent risk factor for in-hospital mortality in pMRSAB.

Comparison of Plasma Concentrations of Posaconazole with the Oral Suspension and Tablet in Korean Patients with Hematologic Malignancies

The posaconazole tablet formulation was developed to have improved bioavailability compared to the oral suspension. Here, we compared posaconazole plasma concentration (PPC) with the posaconazole oral suspension versus the tablet in Korean patients undergoing remission induction chemotherapy for hematologic malignancies. PPC was measured at 3, 8, and 15 days of treatment with the oral suspension (174 patients) or the tablet (40 patients). At all time-points, mean PPC was significantly higher with the tablet compared to the oral suspension. Our findings suggest that posaconazole tablets generate an optimal PPC earlier and in more patients than the oral suspension among Korean patients.

Incidence of disseminated Mycobacterium avium-complex infection in HIV patients receiving antiretroviral therapy with use of Mycobacterium avium-complex prophylaxis

The incidence of disseminated Mycobacterium avium complex (MAC) infection in HIV patients has fallen markedly since the introduction of effective antiretroviral therapy (ART). However, current guidelines still recommend primary prophylaxis. We conducted a retrospective cohort study in a university-affiliated hospital from January 1998 to January 2014. During that period, HIV patients who had at least one CD4 cell count below 50 cells/mm³ and had been treated with ART were enrolled. We compared incidence of disseminated MAC infection in the 12 months after the first CD4 cell count below 50 cells/mm³ between prophylaxis and nonprophylaxis groups. A total of 157 patients were enrolled and the total observation period was 144 patient-years (PY). Thirty-three patients (21%) received primary MAC prophylaxis. The initial CD4 cell count of the prophylaxis group was lower than that of the nonprophylaxis group ( P = 0.024), but the proportion of patients who reached a CD4 cell count >100 cells/mm³ ( P = 0.234) and were virologically suppressed ( P = 0.513) 12 months after ART commencement was not different in the prophylaxis and nonprophylaxis groups. The incidence of MAC did not differ significantly between the groups (3.4/100 PY versus 0.8/100 PY, P = 0.368). Routine MAC prophylaxis may be not required in the era of effective ART.

Clinical and Epidemiologic Characteristics of Spreaders of Middle East Respiratory Syndrome Coronavirus during the 2015 Outbreak in Korea

Nosocomial transmission is an important characteristic of Middle East Respiratory Syndrome Coronavirus (MERS-CoV) infection. Risk factors for transmission of MERS-CoV in healthcare settings are not well defined. During the Korean outbreak in 2015, 186 patients had laboratory-confirmed MERS-CoV infection. Those suspected as a source of viral transmission were categorized into the spreader groups (super-spreader [n = 5] and usual-spreader [n = 10]) and compared to the non-spreader group (n = 171). Body temperature of ≥ 38.5°C (adjusted odds ratio [aOR], 5.54; 95% confidence interval [CI], 1.38-22.30; P = 0.016), pulmonary infiltration of ≥ 3 lung zones (aOR, 7.33; 95% CI, 1.93-27.79; P = 0.003), and a more nonisolated in-hospital days (aOR, 1.32 per 1 day; 95% CI, 1.09-1.60; P = 0.004) were significant risk factors in the spreader group. There was no different clinical factor between super-spreaders and usual-spreaders. Nonisolated in-hospital days was the only factor which tended to be higher in super-spreaders than usual-spreaders (Mean, 6.6 vs. 2.9 days; P = 0.061). Early active quarantine might help reducing the size of an outbreak.

Comparison of clinical characteristics and outcomes of spontaneous bacterial peritonitis and culture negative neutrocytic ascites

OBJECTIVE

Ascitic fluid infections (AFI) in cirrhotic patients can be classified into two groups: spontaneous bacterial peritonitis (SBP) and culture-negative neutrocytic ascites (CNNA). The aim of this study was to compare the clinical characteristics and outcomes of the two groups of patients with AFI.

METHODS

We retrospectively reviewed the medical records of cirrhotic patients with AFI. We evaluated demographic data, clinical presentations of AFI, laboratory findings, liver function, and mortality rates.

RESULTS

Between January 2005 and December 2014, 533 patients with AFI were evaluated; 259 (48.6%) had SBP and 274 (51.4%) CNNA. Ascites neutrophil count (4410/mm³ versus 1046/mm³, p < .001) and the blood culture positive rate (38.1% versus 20.1%, p < .001) were higher in the SBP group, which also had a higher MELD score (24.29 versus 22.05, p = .004). Seven-day mortality was higher in the SBP group (9.4% versus 4.5%, p = .027) but there was no significant difference in 30-day (22.1% versus 17.5%) or 90-day mortality rate (36.1% versus 36.4%).

CONCLUSIONS

Patients in the SBP group had a higher MELD score, ascites neutrophil count, and positive blood culture rate. Although seven-day mortality rate was higher in the SBP group, the 30-day and 90-day mortality rates were similar in the two groups.

Clinical Progression and Cytokine Profiles of Middle East Respiratory Syndrome Coronavirus Infection

Clinical progression over time and cytokine profiles have not been well defined in patients with Middle East respiratory syndrome coronavirus (MERS-CoV) infection. We included 17 patients with laboratory-confirmed MERS-CoV during the 2015 outbreak in Korea. Clinical and laboratory parameters were collected prospectively. Serum cytokine and chemokine levels in serial serum samples were measured using enzyme-linked immunosorbent assay. All patients presented with fever. The median time to defervescence was 18 days. Nine patients required oxygen supplementation and classified into severe group. In the severe group, chest infiltrates suddenly began to worsen around day 7 of illness, and dyspnea developed at the end of the first week and became apparent in the second week. Median time from symptom onset to oxygen supplementation was 8 days. The severe group had higher neutrophil counts during week 1 than the mild group (4,500 vs. 2,200/μL, P = 0.026). In the second week of illness, the severe group had higher serum levels of IL-6 (54 vs. 4 pg/mL, P = 0.006) and CXCL-10 (2,642 vs. 382 pg/mL, P < 0.001). IFN-α response was not observed in mild cases. Our data shows that clinical condition may suddenly deteriorate around 7 days of illness and the serum levels of IL-6 and CXCL-10 was significantly elevated in MERS-CoV patients who developed severe diseases.

Comparison of characteristics of culture-negative pyogenic spondylitis and tuberculous spondylitis: a retrospective study

Background

Differences between the characteristics of culture positive pyogenic spondylitis (CPPS) and tuberculous spondylitis (TS) are well known. However, differences between the characteristics of culture negative pyogenic spondylitis (CNPS) and TS have not been reported; these would be more helpful in clinical practice especially when initial microbiologic examination of blood and/or biopsy tissue did not reveal the causative bacteria in patients with infectious spondylitis.

Methods

We performed a retrospective review of the medical records of patients with CNPS and TS. We compared the characteristics of 71 patients with CNPS with those of 94 patients with TS.

Results

Patients with TS had more previous histories of tuberculosis (9.9 vs 22.3 %, p = 0.034), simultaneous tuberculosis other than of the spine (0 vs 47.9 %, p < 0.001), and positive results in the interferon-gamma release assay (27.6 vs 79.2 %, p < 0.001). Fever (15.5 vs. 31.8 %, p = 0.018), psoas abscesses (15.5 vs 33.0 %, p = 0.011), and paravertebral abscesses (49.3 vs. 74.5 %, p = 0.011) were also more prevalent in TS than CNPS.

Conclusions

Different from or contrary to the previous comparisons between CPPS and TS, fever, psoas abscesses, and paravertebral abscesses are more common in patients with TS than in those with CNPS.

Electronic Alerts with Automated Consultations Promote Appropriate Antimicrobial Prescriptions

Background

To promote appropriate antimicrobial use in bloodstream infections (BSIs), we initiated an intervention program consisting of electronic alerts and automated infectious diseases consultations in which the identification and antimicrobial susceptibility test (ID/AST) results were reported.

Methods

We compared the appropriateness of antimicrobial prescriptions and clinical outcomes in BSIs before and after initiation of the program. Appropriateness was assessed in terms of effective therapy, optimal therapy, de-escalation therapy, and intravenous to oral switch therapy.

Results

There were 648 BSI episodes in the pre-program period and 678 in the program period. The proportion of effective, optimal, and de-escalation therapies assessed 24 hours after the reporting of the ID/AST results increased from 87.8% (95% confidence interval [CI] 85.5–90.5), 64.4% (95% CI 60.8–68.1), and 10.0% (95% CI 7.5–12.6) in the pre-program period, respectively, to 94.4% (95% CI 92.7–96.1), 81.4% (95% CI 78.4–84.3), and 18.6% (95% CI 15.3–21.9) in the program period, respectively. Kaplan-Meier analyses and log-rank tests revealed that the time to effective (p<0.001), optimal (p<0.001), and de-escalation (p = 0.017) therapies were significantly different in the two periods. Segmented linear regression analysis showed the increase in the proportion of effective (p = 0.015), optimal (p<0.001), and de-escalation (p = 0.010) therapies at 24 hours after reporting, immediately after program initiation. No significant baseline trends or changes in trends were identified. There were no significant differences in time to intravenous to oral switch therapy, length of stay, and 30-day mortality rate.

Conclusion

This novel form of stewardship program based on intervention by infectious disease specialists and information technology improved antimicrobial prescriptions in BSIs.

Kinetics of Serologic Responses to MERS Coronavirus Infection in Humans, South Korea

We investigated the kinetics of serologic responses to Middle East respiratory syndrome coronavirus (MERS-CoV) infection by using virus neutralization and MERS-CoV S1 IgG ELISA tests. In most patients, robust antibody responses developed by the third week of illness. Delayed antibody responses with the neutralization test were associated with more severe disease.

First Imported Case of Zika Virus Infection into Korea

Since Zika virus has been spreading rapidly in the Americas from 2015, the outbreak of Zika virus infection becomes a global health emergency because it can cause neurological complications and adverse fetal outcome including microcephaly. Here, we report clinical manifestations and virus isolation findings from a case of Zika virus infection imported from Brazil. The patient, 43-year-old Korean man, developed fever, myalgia, eyeball pain, and maculopapular rash, but not neurological manifestations. Zika virus was isolated from his semen, and reverse-transcriptase PCR was positive for the virus in the blood, urine, and saliva on the 7th day of the illness but was negative on the 21st day. He recovered spontaneously without any neurological complications. He is the first case of Zika virus infection in Korea imported from Brazil.

Comparison of serological assays in human Middle East respiratory syndrome (MERS)-coronavirus infection

Plaque reduction neutralisation tests (PRNT), microneutralisation (MN), Middle East respiratory syndrome (MERS)-spike pseudoparticle neutralisation (ppNT) and MERS S1-enzyme-linked immunosorbent assay (ELISA) antibody titres were compared using 95 sera from 17 patients with MERS, collected two to 46 days after symptom onset. Neutralisation tests correlated well with each other and moderately well with S1 ELISA. Moreover to compare antigenic similarity of genetically diverse MERS-CoV clades, the response of four sera from two patients sampled at two time periods during the course of illness were tested by 90% PRNT. Genetically diverse MERS-CoV clades were antigenically homogenous.

Isolation of Middle East Respiratory Syndrome Coronavirus from a Patient of the 2015 Korean Outbreak

During the 2015 outbreak of Middle East respiratory syndrome coronavirus (MERS-CoV) in Korea, 186 persons were infected, resulting in 38 fatalities. We isolated MERS-CoV from the oropharyngeal sample obtained from a patient of the outbreak. Cytopathic effects showing detachment and rounding of cells were observed in Vero cell cultures 3 days after inoculation of the sample. Spherical virus particles were observed by transmission electron microscopy. Full-length genome sequence of the virus isolate was obtained and phylogenetic analyses showed that it clustered with clade B of MERS-CoV.

Immune reconstitution inflammatory syndrome versus non-immune reconstitution inflammatory syndrome lymphoma in HIV patients on antiretroviral therapy

Little is known about differences between immune reconstitution inflammatory syndrome (IRIS) and non-IRIS lymphoma in HIV patients on antiretroviral therapy (ART). The aim of this study was to describe the characteristics of IRIS and non-IRIS lymphoma in Korean HIV-positive patients on ART compared with lymphoma in those off ART. Of 1490 patients, 41 (3%) had lymphoma. Of these, 27 cases (66%) were classified as lymphoma off ART, eight as IRIS lymphoma, and six as non-IRIS lymphoma on ART. Hodgkin lymphoma was significantly more common among patients with non-IRIS lymphoma on ART than among those with lymphoma off ART (P = 0.005), whereas there was no Hodgkin lymphoma among IRIS lymphoma. Stage IV lymphoma was significantly rarer in non-IRIS lymphoma on ART than in lymphoma off ART (P = 0.007). Non-IRIS lymphoma on ART tends to have a better survival rate than lymphoma off ART (Kaplan-Meier survival analysis, P = 0.167), while IRIS lymphoma exhibited a survival rate similar to lymphoma off ART (P = 0.618). In Korean HIV-positive patients, there were significantly more cases of Hodgkin lymphoma of a less advanced stage in non-IRIS lymphoma on ART than in lymphoma off ART, in contrast to IRIS lymphoma.

Infected Aortic Aneurysm caused by Mycobacterium bovis after Intravesical Bacillus Calmette-Guérin Treatment for Bladder Cancer

A 70-year-old man presented with lower back pain and cyanotic changes in his left lower extremity. He was diagnosed with infected aortic aneurysm and infectious spondylitis. He had received intravesical Bacillus Calmette-Guérin (BCG) therapy up to 1 month before the onset of symptoms. The aneurysm was excised and an aorto-biiliac interposition graft was performed. Mycobacterium tuberculosis complex was cultured in the surgical specimens. Real-time polymerase chain reaction (PCR) targeting the senX3-regX3 region, and multiplex PCR using dual-priming oligonucleotide primers targeting the RD1 gene, revealed that the organism isolated was Mycobacterium bovis BCG. The patient took anti-tuberculosis medication for 1 year, and there was no evidence of recurrence at 18 months follow-up.

Impact of the multiplex polymerase chain reaction in culture-positive samples on appropriate antibiotic use in patients with staphylococcal bacteremia

Rapid identification of the microorganisms in patients with bacteremia may be useful in clinical practice. We evaluated the impact of the multiplex polymerase chain reaction (PCR) on appropriate antibiotic use for patients with gram-positive cocci cluster (GPCC) bacteremia. We divided the GPCC bacteremia cases into a pre-PCR group (2010-2011) and a post-PCR group (2012-2013). A total 664 cases were included in the pre-PCR group; and 570, in the post-PCR group. In methicillin-susceptible Staphylococcus aureus (MSSA) cases, optimal antibiotics were administered earlier in the post-PCR group (77.4h versus 42.6h, P=0.035). Although the proportions of glycopeptide exposure did not differ (54.7% versus 56.7%, P=0.799), the duration of exposure decreased (69.6h versus 30.7h, P=0.004). In methicillin-resistant S. aureus cases, the time to optimal antibiotics administration did not differ (45.4h versus 43.7h, P=0.275). Multiplex PCR test significantly improved the early initiation of optimal antibiotics in MSSA bacteremia and reduced the unnecessary glycopeptide exposure.

Middle East Respiratory Syndrome Coronavirus Superspreading Event Involving 81 Persons, Korea 2015

Since the first imported case of Middle East respiratory syndrome coronavirus (MERS-CoV) infection was reported on May 20, 2015 in Korea, there have been 186 laboratory-confirmed cases of MERS-CoV infection with 36 fatalities. Ninety-seven percent (181/186) of the cases had exposure to the health care facilities. We are reporting a superspreading event that transmitted MERS-CoV to 81 persons at a hospital emergency room (ER) during the Korean outbreak in 2015. The index case was a 35-yr-old man who had vigorous coughing while staying at the ER for 58 hr. As in severe acute respiratory syndrome outbreaks, superspreading events can cause a large outbreak of MERS in healthcare facilities with severe consequences. All healthcare facilities should establish and implement infection prevention and control measure as well as triage policies and procedures for early detection and isolation of suspected MERS-CoV cases.

Why is asymptomatic bacteriuria overtreated?: A tertiary care institutional survey of resident physicians

Background

Asymptomatic bacteriuria (ABU) is common and often leads to unnecessary antimicrobial use. Reducing antibiotic overuse for ABU is therefore an important issue for antimicrobial stewardship. We performed this study to investigate the appropriateness of ABU management and to evaluate physicians’ knowledge and practice regarding ABU.

Methods

We reviewed all urine cultures of ≥10⁵ cfu/mL of bacteria among inpatients in a 900-bed hospital in 2011. Each episode of bacteriuria was classified into ABU or urinary tract infection (UTI). ABU was defined as a positive urine culture (≥10⁵ cfu/mL) without symptoms or signs suggesting UTI. In October 2012 a cross-sectional survey of resident physicians was undertaken using an anonymous, self-administered questionnaire.

Results

We identified 219 ABU cases among 1167 positive urine cultures, of which 70 (32.0 %) were inappropriately treated. Female gender, old age, pyuria, hematuria, and positive nitrite on urinalysis were associated with inappropriate ABU treatment in a multivariate analysis (P < 0.05).

The response rate to the survey was 74.2 % (95/128). The mean knowledge score was 37.3 %, and 33.7 % of respondents were able to distinguish ABU from UTI, but less than half knew the indications for treating ABU. Even after ABU was correctly diagnosed, concerns about postoperative infections (38.6 %), UTI (9.1 %), and abnormal urinalysis (29.5 %) prevented proper management. About half of the respondents reported to prescribing antibiotics for ABU despite knowing they were not indicated.

Conclusions

About one third of ABUs were inappropriately managed. Lack of knowledge and discrepancies between knowledge and practice, contributed to antimicrobial overuse for ABU. Our findings highlight the importance of developing interventions, including education, audit and feedback, to tackle the problem of inappropriate treatment of ABU.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-1044-3) contains supplementary material, which is available to authorized users.

Human granulocytic anaplasmosis, South Korea, 2013

We report a patient with human granulocytic anaplasmosis in South Korea. The patient had fever and thrombocytopenia. Human granulocytic anaplasmosis was confirmed by seroconversion, PCR, and sequence analysis for Anaplasma phagocytophilum. Morulae were observed in the cultured HL-60 cells inoculated with blood from the patient.

Which tissues are best for microbiological diagnosis in patients with pyogenic vertebral osteomyelitis undergoing needle biopsy?

Identification of the causative microorganism is important in the management of pyogenic vertebral osteomyelitis (PVO). The aim of this study was to investigate whether culture positive rates differ between needle biopsy sites in patients with PVO, and which tissues are best for microbiological diagnosis. Between January 2005 and December 2013, we conducted a retrospective cohort study of PVO patients who had soft-tissue abscesses (paraspinal or psoas abscesses) and who received needle biopsy for microbiological diagnosis. Needle biopsy sites were classified into two anatomical categories: vertebral bodies, or soft tissues (intervertebral discs, paraspinal abscesses, or psoas abscesses). A generalized estimating equation model was developed to identify factors associated with tissue-culture positivity. During the study period a total of 136 tissues were obtained by needle biopsy from 128 PVO patients with soft-tissue abscesses. The culture positive rates of vertebral bodies and soft tissues were 39.7% (29/73), and 63.5% (40/63), respectively (p < 0.05). In a multivariate analysis, male gender (adjusted odds ratio (aOR) 2.24, 95% CI 1.00-5.02), higher C-reactive protein (aOR 1.07, 95% CI 1.01-1.15), positive blood culture (aOR 2.57, 95% CI 1.01-6.59), and soft tissues as biopsy site compared with vertebral bodies (aOR 2.28, 95% CI 1.08-4.78) were independent factors associated with tissue culture positivity. Soft tissues were the best sites for microbiological diagnosis in PVO patients undergoing needle biopsy.

Discrepancy in perceptions regarding patient participation in hand hygiene between patients and health care workers

BACKGROUND

Patient participation in hand hygiene programs is regarded as an important component of hand hygiene improvement, but the feasibility of the program is still largely unknown. We examined the perceptions of patients/families and health care workers (HCWs) with regard to patient participation in hand hygiene.

METHODS

A cross-sectional survey of patients/families as well as physicians and nurses was performed using an anonymous, self-administered questionnaire in a 1,000-bed teaching hospital in South Korea.

RESULTS

A total of 152 physicians, 387 nurses, and 334 patients/families completed the survey. The overall response rate was 84%, 85%, and more than 60% among physicians, nurses, and patients/families, respectively. Whereas 75% of patients/families wished to ask HCWs to clean their hands if they did not do so themselves, only 26% of physicians and 31% of nurses supported the participation of patients (P < .001). The most common reason why HCWs disagreed with patient participation was concern about negative effects on their relationship with patients (54%). Regarding the method of patient involvement, patients preferred to assess hand hygiene performance, whereas physicians preferred patients to ask directly.

CONCLUSIONS

There was a significant discrepancy in perceptions regarding patient participation between patients/families and HCWs. Enhanced understanding and acceptance of any new program by both patients and HCWs before its introduction are needed for successful implementation.

Severe fever with thrombocytopenia syndrome, South Korea, 2012

We report a retrospectively identified fatal case of severe fever with thrombocytopenia syndrome (SFTS) in South Korea from 2012. SFTS virus was isolated from the stored blood of the patient. Phylogenetic analysis revealed this isolate was closely related to SFTS virus strains from China and Japan.

Clinical outcomes of spontaneous bacterial peritonitis due to extended-spectrum beta-lactamase-producing Escherichia coli or Klebsiella pneumoniae: a retrospective cohort study

PURPOSE

The aim of this study was to (1) evaluate the clinical outcomes of spontaneous bacterial peritonitis (SBP) due to extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli or Klebsiella pneumoniae (EK) and (2) investigate the relationship between the adequacy of initial antibiotic treatments and patient outcomes.

METHODS

We conducted a retrospective cohort study of cirrhotic patients with SBP caused by EK. We evaluated the 30-day mortality rate and used Cox proportional hazard models to identify risk factors for mortality.

RESULTS

Between January 2006 and December 2012, a total of 231 episodes of SBP due to EK were recorded. Among them, 52 were caused by ESBL-producing EK (ESBL-EK). The 30-day mortality rate was significantly higher in patients with SBP due to ESBL-EK than in those with non-ESBL-producing EK (non-ESBL-EK) (34.6 vs. 18.4 %, respectively; p = 0.013). Multivariate analysis revealed that ESBL production [adjusted HR (aHR) 1.82, 95 % confidence interval (CI) 1.00-3.31], nosocomial infection (aHR 2.24, 95 % CI 1.26-3.95), septic shock (aHR 4.84, 95 % CI 2.70-8.65), higher Child-Pugh score (aHR 1.57, 95 % CI 1.28-1.92), and higher Charlson comorbidity index (aHR 1.37, 95 % CI 1.15-1.64) were independent risk factors for 30-day mortality in the total cohort. When we analyzed patients with SBP due to ESBL-EK separately, septic shock (aHR 3.64, 95 % CI 1.40-9.77), accompanying bacteremia (aHR 3.71, 95 % CI 1.37-10.08), and hepatocellular carcinoma (aHR 3.21, 95 % CI 1.20-8.56) were independent risk factors.

CONCLUSIONS

Both 7- and 30-day mortalities for SBP due to ESBL-EK were significantly higher than for SBP due to non-ESBL-EK. Initial antibiotic choice was not associated with poor clinical outcomes in patients with SBP due to ESBL-EK.

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.

Area under the concentration-time curve to minimum inhibitory concentration ratio as a predictor of vancomycin treatment outcome in methicillin-resistant Staphylococcus aureus bacteraemia

There have been few clinical studies on the association between the 24-h area under the concentration-time curve (AUC24) to minimum inhibitory concentration (MIC) ratio and vancomycin treatment outcomes in methicillin-resistant Staphylococcus aureus (MRSA) infections. Patients with MRSA bacteraemia between July 2009 and January 2012 were analysed retrospectively. All adult patients treated with vancomycin for ≥72 h without dialysis were included. The MIC was determined by Etest and broth microdilution (BMD). Initial steady-state AUC24 was estimated using a Bayesian model, and the AUC24/MIC cut-off value for differentiating treatment success and failure was calculated by classification and regression tree (CART) analysis. In total, 76 patients were enrolled; vancomycin treatment failure occurred in 20 patients (26.3%). Catheter-related infection was the most frequent (35.5%), followed by surgical site infection (26.3%), whilst 25 (32.9%) had complicated infections. In univariate analysis, decreased MRSA vancomycin susceptibility (MIC≥1.5 mg/L) and vancomycin trough levels (15-20 mg/L) were not associated with treatment outcomes. In the CART analysis, low initial vancomycin AUC24/MIC (<430 by Etest; <398.5 by BMD) was associated with a higher treatment failure rate (50.0% vs. 25.0%, P=0.039 by Etest; 45.0% vs. 23.2%; P=0.065 by BMD). In multivariate analysis, low initial vancomycin AUC24/MIC was a significant risk factor for treatment failure [adjusted odds ratio (aOR)=4.39, 95% confidence interval (CI), 1.26-15.35 by Etest; aOR=3.73, 95% CI 1.10-12.61 by BMD]. In MRSA bacteraemia, a low initial vancomycin AUC24/MIC is an independent risk factor for vancomycin treatment failure.

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.

Incidence and risk factors of tuberculosis in patients with human immunodeficiency virus infection

Korea is a low prevalence country for human immunodeficiency virus (HIV) infection and has an intermediate tuberculosis (TB) burden. We previously reported that the incidence of TB in HIV-infected patients was 9.6 cases per 100 person-years (P-Y) between 1988 and 1997. The aims of the present study were to measure any change in incidence from the previous study, and to identify risk factors for TB in HIV-infected patients. We reviewed all medical records of HIV-infected patients who were followed-up in one tertiary hospital between 1998 and 2010. Over the total observation period of 5858.33 P-Y, TB developed in 70 patients (1.19 cases per 100 P-Y; 95% confidence interval [CI], 0.91-1.47 cases per 100 P-Y). Based on Poisson regression, one risk factor associated with TB was an initial CD4+ cell count below 200 cells/µL (relative risk, 2.34; 95% CI, 1.47-3.73). Mean CD4+ cell counts of pulmonary, extrapulmonary, and both pulmonary and extrapulmonary TB were 179.8 cells/µL, 138.3 cells/µL, and 114.2 cells/µL, respectively (P = 0.55). In conclusion, the incidence of TB in HIV-infected patients has decreased since the previous study. An initial CD4+ cell count below 200 cells/µL is an independent risk factor for development of TB in HIV-infected patients.

Risk factors for febrile neutropenia during chemotherapy for HIV-related lymphoma

We evaluated risk factors for neutropenic fever and febrile prolonged neutropenia during vincristine-including chemotherapy to treat HIV-related lymphoma to investigate whether protease inhibitor (PI) treatment is associated with infectious complications due to drug interactions with chemotherapeutic agents. We included all HIV patients who received chemotherapy including vincristine for lymphoma at a single referral center in 1999-2010. Neutropenic fever was defined as absolute neutrophil count < 500 cells/µL with body temperature over 38℃; and prolonged neutropenia was defined if it persisted over 7 days. CODOX-M/IVAC and Stanford regimens were considered high-risk regimens for prolonged neutropenia. We analyzed 48 cycles of chemotherapy in 17 HIV patients with lymphoma. There were 22 neutropenic fever and 12 febrile prolonged neutropenia events. In multivariate analysis, neutropenic fever was associated with old age and low CD4 cell count, but not with PI use or ritonavir-boosted PI use. Low CD4 cell count and high-risk regimens were associated with febrile prolonged neutropenia. Neutropenic fever and febrile prolonged neutropenia is associated with old age, low CD4 cell count, and high-risk regimens, but not PI use, in HIV patients undergoing chemotherapy including vincristine for lymphoma.

Tigecycline in carbapenem-resistant Acinetobacter baumannii bacteraemia: susceptibility and clinical outcome

Although tigecycline is considered one of the few therapeutic options for carbapenem-resistant Acinetobacter baumannii (CRAB) bacteraemia, its role in the treatment of CRAB bacteraemia remains unclear. We describe the clinical outcomes of 9 patients who received tigecycline for CRAB bacteraemia. Although all CRAB blood isolates were susceptible to tigecycline, 5 (56%) deaths were related to CRAB bacteraemia and 1 case of breakthrough CRAB bacteraemia was observed during tigecycline therapy. Clinical outcomes of tigecycline therapy may be poor in patients with tigecycline-susceptible CRAB bacteraemia, although multiple factors including delayed treatment could contribute to the poor outcomes.

Differentiating rapid- and slow-growing mycobacteria by difference in time to growth detection in liquid media

Nontuberculous mycobacteria (NTM) are classified into 2 categories: slow-growing mycobacteria (SGM) and rapid-growing mycobacteria (RGM), based on interval to colony formation by subculture on solid media. However, little is known about the growth rate of NTM in liquid broth media. We evaluated the differences in time to growth detection (TGD) of RGM and SGM in liquid broth media according to acid-fast stain. Among the 696 NTM isolates, 201 were RGM and 495 were SGM. In acid-fast bacilli (AFB)-negative specimens, the mean TGD was 133 h for RGM and 269 h for SGM (P < 0.001). In AFB-positive specimens, the mean TGD was 112 ± 37 h for RGM and 155 ± 125 h for SGM (P = 0.063). In the AFB-negative group, a cut-off value of 6 days was most effective for distinguishing SGM from RGM; however, in the AFB-positive group, an appropriate cut-off value was hard to define with TGD only.

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.