Interim Estimates of 2023-2024 Seasonal Influenza Vaccine Effectiveness Among Adults in Korea

In the 2023-2024 season, the influenza epidemic in South Korea peaked earlier than in recent years. In this study, we aimed to estimate the interim vaccine effectiveness (VE) of the influenza vaccination to prevent influenza during the early season. From November 1, 2023, to December 31, 2023, we enrolled 2,632 subjects with influenza-like illness from eight hospitals participating in hospital-based influenza morbidity and mortality surveillance. A retrospective test-negative case-control study was conducted to estimate the VE. The results showed an adjusted VE of 22.5% (95% confidence interval [CI], 6.6 to 35.8) for the total population. The adjusted VE was 22.3% (95% CI, 6.1 to 35.7) for influenza A and 9.4% (95% CI, -51.3 to 45.7) for influenza A/H1N1. Full results of the analysis will be reported.

Effectiveness of Bivalent mRNA Booster Vaccine Against COVID-19 in Korea

BACKGROUND

Bivalent booster mRNA vaccines containing the omicron-variant strains have been introduced worldwide in the autumn of 2022. Nevertheless, the omicron subvariants evoked another large coronavirus disease 2019 (COVID-19) pandemic wave in late 2022 and early 2023.

METHODS

A retrospective, test-negative, case-control study was conducted to estimate the vaccine effectiveness (VE) of bivalent COVID-19 vaccines in 8 university hospitals between January and February 2023. The case and control groups were divided based on nasopharyngeal COVID-19 real-time polymerase chain reaction results and matched based on age, sex, hospital, and date (week) of the test performed. The VE of the BA.1- or BA.4/BA.5-based mRNA vaccines were estimated. VE was calculated using the 1-adjusted odds ratio from multivariable logistic regression.

RESULTS

In total, 949 patients and 947 controls were enrolled in this study. VE for the BA.4/BA.5-based bivalent mRNA vaccine was 43% (95% confidence interval [CI], 17, 61%). In subgroup analysis based on age and underlying medical conditions, BA.4/BA.5-based bivalent mRNA vaccine was effective against old adults aged ≥ 65-years (VE, 55%; 95% CI, 23, 73%) and individuals with comorbidities (VE, 54%; 95% CI, 23, 73%). In comparison, the BA.1-based bivalent mRNA vaccine did not demonstrate statistically significant effectiveness (VE, 25%; 95% CI, -8, 49%).

CONCLUSION

The BA.4/BA.5-based bivalent mRNA booster vaccine provided significant protection against COVID-19 in the Korean adults, especially in the older adults aged ≥ 65 years and in individuals with underlying medical conditions.

Effective Vaccination and Education Strategies for Emerging Infectious Diseases Such as COVID-19

Social isolation and control owing to coronavirus disease 2019 (COVID-19) are easing; however, concerns regarding new infectious diseases have not disappeared. Given epidemic experiences such as severe acute respiratory syndrome (SARS), the influenza pandemic, Middle East respiratory syndrome (MERS), and COVID-19, it is necessary to prepare for the outbreak of new infectious diseases and situations in which large-scale vaccinations are required. Although the development of vaccines against COVID-19 has contributed greatly to overcoming the pandemic, concerning vaccine side effects from the general public, including medical personnel, and decreased confidence in vaccine efficacy and side effects, present many challenges in promoting and educating vaccinations for new infectious diseases in the future. In addition to plans to develop vaccines for the outbreak of new infectious diseases, education and promotion plans are necessary to administer the latest developments of vaccines to the general public. Moreover, efforts are needed to secure the necessity, legitimacy, and evidence for rapid vaccination on a large scale at the national level. It is also necessary to carefully prepare scientific bases and explanatory statements so that the general public can easily understand them. This study aimed to establish vaccine strategies and vaccination education plans for new infectious diseases that may occur in the future. Many ways to promote vaccination to the general public and healthcare workers should be prepared to ensure that the latest vaccines against new infectious diseases are administered safely. Thus, education and promotion of vaccine efficacy and safety based on specific data from clinical studies are necessary.

Changes in the characteristics of community-onset fluoroquinolone-resistant Escherichia coli isolates causing community-acquired acute pyelonephritis in South Korea

PURPOSE

This study aimed to examine the changes in the characteristics of community-onset fluoroquinolone-resistant (FQ-R) Escherichia coli isolates causing community-acquired acute pyelonephritis (APN) in South Korea.

METHODS

Blood or urine samples were prospectively collected from patients aged ≥15 years with community-acquired APN who were admitted to one of the eight Korean hospitals included in this study between September 2017 and August 2018. Phylogenetic typing, multilocus sequence typing, and molecular characterization of β-lactamase resistance and plasmid-mediated quinolone resistance (PMQR) determinants were performed. The data were compared with those from a previous study with the same design conducted in 2010-2011.

RESULTS

A total of 300 and 346 isolates were identified in 2010-2011 and 2017-2018, respectively. Among them, 76 (22.0%) and 77 (25.7%) FQ-R isolates were identified in 2010-2011 and 2017-2018, respectively. A significantly higher antimicrobial resistance against third-to fourth-generation cephalosporins, including cefotaxime (23.9% vs. 77.9%, P < 0.001), were observed among FQ-R isolates in 2017-2018 than among those in 2010-2011. A higher proportion of ST131 isolates (27.6% vs. 66.2%, P < 0.001), as well as isolates that had extended-spectrum β-lactamase (ESBL)/plasmid-mediated AmpC β-lactamase (PABL) (23.7% vs. 79.2%, P < 0.001), was observed in 2017-2018 than in 2010-2011. Further, more PMQR determinants (11.8% vs. 40.8%, P < 0.001) were observed in 2017-2018 than in 2010-2011.

CONCLUSIONS

Among uropathogenic FQ-R E. coli isolates in South Korea, the prevalence of ST131 and the proportion of isolates containing ESBL and/or PMQR determinants have increased.

Relationship between the appropriateness of antibiotic treatment and clinical outcomes/medical costs of patients with community-acquired acute pyelonephritis: a multicenter prospective cohort study

BACKGROUND

Inappropriate use of antibiotics not only increases antibiotic resistance as collateral damage but also increases clinical failure rates and medical costs. The purpose of this study was to determine the relationship between the appropriateness of antibiotic prescription and outcomes of community-acquired acute pyelonephritis (CA-APN).

METHODS

A multicenter prospective cohort study was conducted at eight hospitals in Korea between September 2017 and August 2018. All hospitalized patients aged ≥ 19 years who were diagnosed with CA-APN on admission were recruited. The appropriateness of empirical and definitive antibiotics, as well as the appropriateness of antibiotic treatment duration and route of administration, was evaluated in accordance with the guideline and expert opinions. Clinical outcomes and medical costs were compared between patients who were administered antibiotics 'appropriately' and 'inappropriately.'

RESULTS

A total of 397 and 318 patients were eligible for the analysis of the appropriateness of empirical and definitive antibiotics, respectively. Of them, 10 (2.5%) and 18 (5.7%) were administered 'inappropriately' empirical and definitive antibiotics, respectively. Of the 119 patients whose use of both empirical and definitive antibiotics was classified as 'optimal,' 57 (47.9%) received antibiotics over a longer duration than that recommended; 67 (56.3%) did not change to oral antibiotics on day 7 of hospitalization, even after stabilization of the clinical symptoms. Patients who were administered empirical antibiotics 'appropriately' had shorter hospitalization days (8 vs. 10 days, P = 0.001) and lower medical costs (2381.9 vs. 3235.9 USD, P = 0.002) than those who were administered them 'inappropriately.' Similar findings were observed for patients administered both empirical and definitive antibiotics 'appropriately' and those administered either empirical or definitive antibiotics 'inappropriately'.

CONCLUSIONS

Appropriate use of antibiotics leads to better outcomes, including reduced hospitalization duration and medical costs.

Comparison of the clinical characteristics of community-acquired acute pyelonephritis between male and female patients

BACKGROUND

Community-acquired acute pyelonephritis (CA-APN) is relatively rare in men. This study aimed to compare the clinical characteristics of CA-APN between male and female patients.

METHODS

We prospectively collected the clinical and microbiological data of hospitalized CA-APN patients aged ≥19 years in South Korea from March 2010 to February 2011 in 11 hospitals and from September 2017 to August 2018 in 8 hospitals. Only the first episodes of APN of each patient during the study period were included.

RESULTS

From 2010 to 2011, 573 patients from 11 hospitals were recruited, and from 2017 to 2018, 340 patients were recruited from 8 hospitals. Among them, 5.9% (54/913) were male. Male patients were older (66.0 ± 15.2 vs. 55.3 ± 19.0 years, P < 0.001), had a higher Charlson comorbidity index (1.3 ± 1.5 vs. 0.7 ± 1.2, P = 0.027), and had a higher proportion of structural problems in the urinary tract (40.7% vs. 6.1%, P < 0.001) than female patients. Moreover, the total duration of antibiotic treatment was longer (21.8 ± 17.8 d vs. 17.3 ± 9.4 d, P = 0.001) and the proportion of carbapenem usage was higher (24.1% vs. 9.5%, P = 0.001) in men than in women. Male patients were hospitalized for longer durations than female patients (median, 10 d vs. 7 d, P < 0.001).

CONCLUSIONS

Male CA-APN patients were older and had more comorbidities than female CA-APN patients. In addition, male patients received antibiotic treatment for a longer duration than female patients.

1667. Change in characteristics of community-onset ciprofloxacin-resistant E. coli isolates causing community-acquired acute pyelonephritis in South Korea

Background

The aim of this study was to examine the change in characteristics of community-onset ciprofloxacin-resistant (CIP-R) E. coli isolates causing community-acquired acute pyelonephritis (CA-APN) in South Korea between 2010-2011 and 2017-2018.

Methods

E. coli samples isolated from the blood or urine were collected from patients with CA-APN aged 19 years and more who were admitted to 8 Korean hospitals from September 2017 to August 2018, prospectively. One isolate was collected from each patient. Phylogenetic typing, multilocus sequence typing (MLST), and molecular characterization of β-lactamase resistance and plasmid-mediated quinolone resistance (PMQR) determinants were performed. The data were compared with those from the previous study with same design in 2010-2011.

Results

A total of 346 and 300 isolates were collected during 2017-2018 and 2010-2011, respectively. Among them, 76 (22.0%) and 77 (25.7%) were CIP-R isolates. Significantly higher antimicrobial resistance against ampicillin (75.7% vs. 100%, P < 0.001) and cefotaxime (23.9% vs. 77.9%, P < 0.001) were observed for isolates in 2017-2018 compared to those in 2010-2011. The proportion of phylogenic group B2 had increased significantly (44.7% vs. 79.2%, P < 0.001). As for MLST, the proportion of ST131 (27.6% vs. 66.2%, P < 0.001) had increased while that of ST393 (18.4% vs. 3.9%, P =0.004) had decreased significantly. Higher proportion of CIP-R E. coli isolates in 2017-2018 had extended-spectrum β-lactamase (ESBL)/plasmid-mediated AmpC β-lactamase (PABL) (23.7% vs. 79.2%, P < 0.001) and PMQR determinant (11.8% vs. 40.8%, P < 0.001) compared to those in 2010-2011.

Phlogenetic tree

Analyzed by SplitsTree

Conclusion

Among uropathogenic CIP-R E. coli isolates in South Korea, ST131 predominance had become more prominent and the proportion of containing ESBL/PABL and/or PMQR determinants had increased.

Disclosures

All Authors: No reported disclosures

A comparison of epidemiology and clinical outcomes between influenza A H1N1pdm09 and H3N2 based on multicenter surveillance from 2014 to 2018 in South Korea

BACKGROUND

After pandemic, A(H1N1)pdm09 is generally known to be associated with younger adults' infection and greater severity than seasonal A(H3N2) but some inconsistences between recent studies exist.

OBJECTIVES

We aimed to compare the epidemiology and clinical outcomes of A(H1N1)pdm09 and A(H3N2) to verify and consolidate about the knowledge of known differences of subtypes.

METHODS

Data were retrospectively collected from the hospital-based influenza morbidity and mortality surveillance in South Korea in nine tertiary care hospitals, from August 31, 2014, to August 25, 2018. Patients with H1N1pdm09 or H3N2 infection admitted in the emergency room or ward were recruited.

RESULTS

A total of 1747 patients had influenza A and were divided into two groups those with A(H1N1)pdm09 (n = 240) and those with A(H3N2) (n = 1507). A(H1N1)pdm09 group had younger age (mean age ± standard deviation 50.0 ± 18.8 in H1N1 vs 53.4 ± 21.1 in H3N2, P = .030), lower influenza vaccination (27.9% vs 43.9%, P < .001) and pneumococcal vaccination rates (41.0% vs 51.9%, P < .001), and fewer underlying diseases (67.5% vs 74.0%, P = .035) than the A(H3N2) group. Influenza A subtypes were not associated with pneumonia risk (adjusted odds ratios [AOR] of A(H1N1)pdm09: 0.7 [95% confidence interval [CI]: 0.4-1.2, P = .172]) and in-hospital mortality (hazard ratio (HR) of A(H1N1)pdm09: 1.0 (95% CI: 0.3-3.1, P = .983)). Influenza vaccination reduced in-hospital mortality in hospitalized patients (HR: 0.3 (95% CI: 0.1-0.7), P = .005).

CONCLUSIONS

A(H1N1)pdm09 infection was more common in younger patients without significant difference in pneumonia risk and in-hospital mortality between subtypes. Influenza vaccination was associated with reduced in-hospital mortality.

Effectiveness of repeated influenza vaccination among the elderly population with high annual vaccine uptake rates during the three consecutive A/H3N2 epidemics

BACKGROUND

Annually, about 80% of the Korean elderly aged ≥65 years receive influenza vaccination. Repeated annual vaccination has been suggested as an important factor of poor influenza vaccine effectiveness (VE), though reported conflicting results.

METHODS

During the consecutive A/H3N2-dominant influenza seasons between 2012 and 2015, we comparatively evaluated the VE (repeated vs. current season only) against laboratory-confirmed influenza, pneumonia and hospitalization in the elderly aged ≥65 years with influenza-like illness (ILI). Clinical and demographic data were collected prospectively, and vaccination status of prior and current seasons was verified using the immunization registry data of Korean Centers for Disease Control and Prevention.

RESULTS

During the first A/H3N2-dominant season in 2012-2013, influenza vaccine showed statistically significant effectiveness against influenza A infection only and when vaccinated in the current season only (VE 53%, 95% CI 15-77). In the latter two seasons (2013-2015 years), the adjusted VE for influenza A was indistinguishable between repeated vaccination and vaccination in the current season only.

CONCLUSION

During consecutive influenza A/H3N2 epidemics, poor influenza vaccine effectiveness may be more pronounced among the elderly population with a high annual vaccine uptake rate.

1451. Change in Clinical Characteristics of Community-Acquired Acute Pyelonephritis in South Korea: Comparison Between 2010–2011 and 2017–2018

Background

The aim of this study was to examine the change in clinical characteristics of community-acquired acute pyelonephritis (CA-APN) in South Korea between 2010–2011 and 2017–2018.

Methods

We recruited all CA-APN patients with age ≥19 years who visited 4 hospitals in South Korea from September 2017 to August 2018, prospectively. The inclusion criteria were: (i) presence of fever (body temperature ≥37.8°C), (ii) pyuria [≥5–9 white blood cells per high power field (WBC/HPF)], and (iii) clinical symptoms or signs relevant to APN. Patients diagnosed with APN more than 48 hours after admission, those transferred from other hospitals during treatment of APN, those with other reasons for fever and pyuria, and those with insufficient data were excluded. Each patient was included for the first episode during the study period. The collected data were compared with those from the previous study with the same design in 2010–2012, in which the same hospitals were participated.

Results

A total of 349 and 472 patients were recruited during 2017–2018 and 2010–2011, respectively. E. coli was the most common causative pathogen for CA-APN in both periods (87.5% vs. 86.6%, P = 0.727). Significantly higher antimicrobial resistance against fluoroquinolone (33.5% vs. 21.0%, P = 0.001), cefotaxime (34.8% vs. 7.6%, P P = 0.040) were observed for E. coli isolates in 2017–2018 compared with those in 2010–2011. The patients in 2017–2018 were older (60.71±17.29 vs. 55.77±18.60, P <0.001) and had higher Charlson’s comorbidity index (1.04±1.39 vs. 0.68±1.17, P<0.001) than those in 2010–2011. Total duration of antibiotic treatment increased from 15.40 ± 6.35 days in 2010–2011 to 21.74 ± 11.72 days in 2017–2018, P <0.001); the proportion of patients using carbapenem increased from 6.1% in 2010–2011 to 26.6% in 2010–2011 (P < 0.001). The median days of admission was higher for patients in 2017–2018 than those in 2010–2011 (10 vs. 8, P < 0.001).

Conclusion

Patients with CA-APN in South Korea were aging. Antimicrobial resistance of E. coli to almost all antibiotic classes, especially third-generation cephalosporin, increased significantly and total duration of antibiotic treatment and proportion of carbapenem usage increased, consequently.

Disclosures

All authors: No reported disclosures.

A Phase III Study to Evaluate the Immunogenicity and Safety of GC1107 (Adult Tetanus Diphtheria Vaccine) in Healthy Adults

BACKGROUND

This study was conducted to assess the immunogenicity and safety of GC1107 (adult tetanus diphtheria [Td] vaccine). The primary goal was to evaluate the non-inferiority of the immunogenicity of GC1107 compared to the control vaccine. Additionally, the safety profiles of GC1107 and the control vaccine were compared.

METHODS

The subjects were adults ≥ 18 years old who were not injected with Td or adult tetanus-diphtheria-pertussis (TdaP) vaccine within the recent 5 years. A total of 253 subjects were enrolled and randomized to either the GC1107 group or the control group. For immunogenicity assessment, blood samples were collected at baseline and 28 days after vaccination and antibody titer of diphtheria and tetanus were assessed.

RESULTS

The seroprotection rates of diphtheria and tetanus were 89.76% and 91.34%, respectively, in the GC1107 group, and 87.80% and 86.99% in the control group. The geometric mean titer (GMT) of the anti-diphtheria antibody increased after vaccination in both groups, showing no significant difference between the groups (P = 0.139). The anti-tetanus GMTs after vaccination also showed comparable increases in both groups, and showed no significant difference (P = 0.860). In the safety evaluation, solicited local adverse reactions occurred in 81.2% of the subjects in the GC1107 group and in 86.4% of the subjects in the control group. Solicited systemic adverse events occurred in 33.2% of the subjects in the GC1107 group and in 47.2% of the subjects in the control group, which did not reach statistical significance.

CONCLUSION

This phase III study demonstrated non-inferiority in immunogenicity and comparable safety of GC1107 compared with the control Td vaccine.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02361866.

Immunogenicity and safety of an egg-based inactivated quadrivalent influenza vaccine (GC3110A) versus two inactivated trivalent influenza vaccines with alternate B strains: A phase Ⅲ randomized clinical trial in adults

Two antigenically distinct influenza B lineage viruses (Yamagata/Victoria) have been co-circulating globally since the mid-1980s. The quadrivalent influenza vaccine (QIV) may provide better protection against unpredictable B strains. We conducted a randomized, double-blind, phase III trial to evaluate the immunogenicity and safety of an egg-based inactivated, split-virion QIV (GC3110A). Subjects aged ≥ 19 years were randomized 2:1:1 to be vaccinated with QIV- GC3110A, trivalent influenza vaccine (TIV) containing the Yamagata lineage strain (TIV-Yamagata), or TIV containing the Victoria lineage strain (TIV-Victoria). Hemagglutination inhibition assays were performed 21 days post-vaccination. Solicited/unsolicited adverse events (AEs) were assessed within 21 days after vaccination, while serious AEs were reported up to six months after vaccination. A total of 1,299 were randomized to receive QIV-GC3110A (648 subjects), TIV-Yamagata (325 subjects), or TIV-Victoria (326 subjects). Compared to the TIVs, the QIV-GC3110A met the non-inferiority criteria for all four subtype/lineage strains with respect to the geometric mean titer (GMT) ratio and the difference of seroconversion rate. The safety profiles of QIV-GC3110A were consistent with those of TIV. In conclusion, QIV-GC3110A is safe, immunogenic, and comparable to strain-matched TIV.

Significant circulation of influenza B viruses mismatching the recommended vaccine-lineage in South Korea, 2007-2014

We aimed to characterize the lineages of influenza B viruses obtained from clinical specimens during the 2007-2014 seasons in South Korea. RT-PCR for the partial hemagglutinin gene of influenza B virus was performed on laboratory-confirmed influenza B samples from the 2007-2008 season to 2013-2014 season. A phylogenetic tree was generated, and current influenza vaccine strains for the Northern Hemisphere were used as representative strains of Victoria and Yamagata lineages. A total of 571 influenza B virus sequences were analyzed. During the 2009-2010 season, most of the circulating influenza B viruses matched the vaccine strain; 91.0% (91/100) of viruses belonged to the Victoria lineage. In the 2007-2008, 2011-2012, and 2013-2014 seasons, co-circulation of each influenza B lineage was found with a match ratio to the vaccine strain of 53.2% (42/79), 40.9% (63/154), and 58.3% (134/230), respectively. Overall, 41.7% (238/571) of the circulating influenza B viruses belonged to the lineage mismatching the vaccine strain. During the seven influenza seasons, influenza B epidemics were substantial in four seasons in South Korea. Significant mismatches of the vaccine and lineage of the circulating influenza B viruses were found. The current trivalent influenza vaccine may not be fully suitable for effective protection against influenza B.

Immunogenicity and safety of a cell culture-derived inactivated quadrivalent influenza vaccine (NBP607-QIV): A randomized, double-blind, multi-center, phase III clinical trial in adults and elderly subjects

BACKGROUND

The influenza B virus has two lineages; Yamagata and Victoria. The two lineages are antigenically distinct and it is difficult to expect cross-protection between the lineages. Actually, the mismatch between circulating influenza B viruses and vaccine strains has been occurred frequently. The cell-culture system for the production of influenza vaccine can contribute to improve vaccine strain selection and expand vaccine supplies. We investigated the immunogenicity and safety of cell culture-derived quadrivalent inactivated influenza vaccine (NBP607-QIV) in adults and elderly subjects.

METHODS

A randomized controlled phase III trial was undertaken in 10 university hospitals in the Republic of Korea (Clinical trial Number-NCT02467842). Adults (aged 19-59 years) and elderly subjects (aged ≥60 years) were randomly assigned in a 2:1:1 ratio to NBP607-QIV versus cell culture-based trivalent inactivated influenza vaccine-Yamagata (NBP607-Y) and cell culture-based trivalent inactivated influenza vaccine-Victoria (NBP607-V). Immunogenicity was assessed 3 weeks after vaccination by hemagglutination inhibition assay. Safety was assessed for 6 months post-vaccination: solicited adverse events (AEs) for 7 days, unsolicited AEs for 21 days and serious adverse events (SAEs) for 6 months. AEs were sub-classified as adverse drug reactions (ADRs) according to the causality.

RESULTS

A total of 1,503 participants were randomly assigned to NBP607-QIV (n = 752), NBP607-Y (n = 373) and NBP607-V (n = 378). The seroconversion rates of NBP607-QIV were 52.4%, 51.2%, 43.7% and 55.8% against A/H1N1, A/H3N2, B/Yamagata and B/Victoria, respectively. Non-inferiority against shared strains and superiority against alternate-lineage B strains were demonstrated for NBP607-QIV vs. NBP607-Y and NBP607-V. A total of 730 reactions occurred in 324 (43.1%) subjects of NBP607-QIV group. Majority of ADRs was solicited (99.2%) and mild (90.3%) in intensity. In adults (aged 19-59 years), solicited local AEs were slightly more frequent in NBP607-QIV group than NBP607-Y or NBP607-V group (40.9%, 33.4% and 32.5%, respectively). One SAE was observed among NBP607-QIV group, which was considered to be unrelated to the study vaccine within 3 weeks of vaccination and no vaccine-related SAEs were reported up to 6 months after vaccination.

CONCLUSIONS

NBP607-QIV is a safe, well-tolerated and immunogenic influenza vaccine in Korean adults and elderly subjects.

Disease burden of 2013-2014 seasonal influenza in adults in Korea

BACKGROUND

This study was performed to investigate the disease burden of seasonal influenza in adults ≥20 years of age in Korea, based on surveillance data from the Hospital-based Influenza Morbidity & Mortality Surveillance (HIMM) network.

MATERIALS AND METHODS

The HIMM network is composed of two surveillance systems: emergency room-based and inpatients-based surveillance. A total of ten university hospitals all over the country are included in the surveillance network. The adult catchment population of the HIMM network was calculated by using the data of each hospital and the database of the Health Insurance Review and Assessment Service (HIRA) of Korea. The incidence rates of laboratory-confirmed medically-attended influenza, laboratory-confirmed influenza-related admission and laboratory-confirmed influenza-related death were calculated based on the catchment population. The socioeconomic burden of influenza was estimated using the human capital approach.

RESULTS

During the 2013-2014 influenza season, the calculated adult catchment population of the HIMM network was 1,380,000. The incidence of medically-attended laboratory-confirmed influenza infection was 242.8 per 100,000 adults. The incidence of laboratory-confirmed influenza-related admission was 57.9 per 100,000 adults. The incidence of laboratory-confirmed influenza-related death was 3.1 per 100,000 adults. The total socioeconomic cost of 2013-2014 seasonal influenza in Korean adult population was estimated as 125 million USD (1 USD = 1,100 KRW).

CONCLUSION

The disease burden of 2013-2014 seasonal influenza in Korean adult population is very high and indicates that more active prevention and control policies will be needed to decrease the burden. Additional researches will be needed to assess the burden of seasonal influenza in the Korean child population.

Randomized, double-blind, multi-center, phase III clinical trial to evaluate the immunogenicity and safety of MG1109 (egg-based pre-pandemic influenza A/H5N1 vaccine) in healthy adults

Considering the pandemic potential of avian influenza A/H5N1, development of an effective and well-tolerated vaccine is an essential part of pandemic preparedness plans. This phase III, randomized, double-blind study was conducted to assess the immunogenicity and safety profile of an alum-adjuvanted, whole virion, pre-pandemic influenza A/H5N1 vaccine (MG1109). Healthy individuals were randomly assigned, in a 3:1 ratio, to receive two doses of either MG1109 or placebo containing alum gel. Immunogenicity was determined by hemagglutination inhibition (HI) and microneutralization (MN) assays. Solicited and unsolicited adverse events were assessed after vaccination. Among 420 enrolled subjects, 418 were available for safety analysis, and 298 MG1109 recipients were available for per-protocol immunogenicity analyses. According to the HI assays, after two vaccine doses, all three of the Committee for Medicinal Products for Human Use (CHMP) criteria were met against the vaccine strain for all age groups: seroprotection rate = 74.8% (95% CI: 69.9 - 79.8), seroconversion rate = 67.8% (95% CI: 62.5-73.1), and geometric mean titer ratio (GMTR) = 5.9 (95% CI: 5.4 - 6.4). According to the MN assays, the GMTR was 2.4 (95% CI: 2.1 - 2.7) and 7.0 (95% CI: 6.3 - 7.9) three weeks after the first and second vaccine doses, respectively. Solicited local and systemic adverse events were mostly mild to moderate and were not significantly different between MG1109 and placebo recipients. In conclusion, two-dose administration of alum-adjuvanted H5N1 pre-pandemic influenza vaccine (MG1109) was highly immunogenic and tolerable in adults.

Immunogenicity and safety of a 13-valent pneumococcal conjugate vaccine and an MF59-adjuvanted influenza vaccine after concomitant vaccination in ⩾60-year-old adults

BACKGROUND

Concomitant administration of influenza and pneumococcal vaccines could be an efficient strategy to increase vaccine uptake among older adults. Nevertheless, immune interference and safety issues have been a concern when more than one vaccines are administered at the same time.

METHODS

Subjects aged ⩾60years were randomized in a 1:1:1 ratio to receive MF59-adjuvanted trivalent inactivated influenza vaccine (MF59-aTIV)+13-valent pneumococcal conjugate vaccine (PCV13) (Group 1), PCV13 alone (Group 2), or MF59-aTIV alone (Group 3). Hemagglutination inhibition (HI) and opsonophagocytic activity (OPA) assays were used to compare immunogenicity after single or concomitant vaccination.

RESULTS

A total of 1149 subjects (Group 1, N=373; Group 2, N=394; Group 3, N=382) were available for the assessment of immunogenicity and safety. All groups met immunogenicity criteria for the influenza vaccine in older adults with similar seroprotection rates, seroconversion rates, and geometric mean titer (GMT) fold-increases, irrespective of concomitant vaccination. For each pneumococcal serotype, OPA titers increased markedly after the PCV13 vaccination, irrespective of the concomitant influenza vaccination. After concomitant administration, the non-inferiority criteria of GMT ratios were met for all three influenza subtypes and 13 pneumococcal serotypes. No vaccine-related serious adverse events occurred.

CONCLUSIONS

Concomitant MF59-aTIV and PCV13 administration showed no interference with antibody response and showed good safety profiles. (Clinical Trial Number - NCT02215863).

Comparison of Preferred Bite Sites Between Mites and Ticks on Humans in Korea

Identification of mite and tick bite sites provides important clinical information. The predominant mite species in Korea associated with scrub typhus are Leptotrombidium pallidum and Leptotrombidium scutellare The most abundant tick species is Haemaphysalis longicornis To date, there has been no comparative study on preferred bite sites between mites and ticks in humans. This study included a review of medical records and a field study. For mite bite sites, eschars were checked on 506 patients with scrub typhus, confirmed by indirect immunofluorescence assay or nested polymerase chain reaction on the 56-kDa type-specific antigen gene of Orientia tsutsugamushi Tick bite sites were identified and marked on a diagram for 91 patients who experienced tick bites within the previous year through a field epidemiological investigation. The mite and tick bite sites in Koreans were compared. The most frequently observed mite bite sites were the anterior chest, including the axillae (29.1%) and the abdominal region, including the inguinal area (26.1%). Tick bite sites were most frequent on the lower extremities (33.0%), followed by the abdominal region, including the inguinal area (26.4%), and upper extremities (26.4%). The distribution was significantly different between mite and tick bite sites (P < 0.001). There was a statistically significant difference in the mite bite (P = 0.001), but not tick bite sites (P = 0.985), between men and women. This is the first report on the differences between tick and mite bite sites, and may help clinicians reach a rapid diagnosis of mite- or tick-borne infection.

Use of cefuroxime for women with community-onset acute pyelonephritis caused by cefuroxime-susceptible or -resistant Escherichia coli

BACKGROUND/AIMS

Efforts to decrease the use of extended-spectrum cephalosporins are required to prevent the selection and transmission of multi-drug resistant pathogens, such as extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae. The objectives of this study were to assess the clinical efficacy of intravenous cefuroxime as an empirical antibiotic for the treatment of hospitalized women with acute pyelonephritis (APN) caused by Escherichia coli.

METHODS

We analyzed the clinical and microbiologic database of 328 hospitalized women with community-onset APN.

RESULTS

Of 328 women with APN, 22 patients had cefuroxime-resistant E. coli APN, and 306 patients had cefuroxime-susceptible E. coli APN. The early clinical success rates were significantly higher (p = 0.001) in the cefuroxime-susceptible group (90.8%, 278/306) than in the cefuroxime-resistant group (68.2%, 15/22) at 72 hours. The clinical cure rates at 4 to 14 days after completing antimicrobial therapy were not significantly different in the cefuroxime-resistant or -susceptible groups, with 88.2% (15/17) and 97.8% (223/228; p = 0.078), respectively. The microbiological cure rates were not significantly different and were 90.9% (10/11) and 93.4% (128/137), respectively (p = 0.550). The median duration of hospitalization in the cefuroxime-resistant and -susceptible groups was 10 days (interquartile range [IQR], 8 to 13) and 10 days (IQR, 8 to 14), respectively (p =0.319).

CONCLUSIONS

Cefuroxime, a second-generation cephalosporin, can be used for the initial empirical therapy of community-onset APN if tailored according to uropathogen identification and susceptibility results, especially in areas where the prevalence rate of ESBL-producing uropathogens is low.

Comparison of Second- and Third-Generation Cephalosporin as Initial Therapy for Women with Community-Onset Uncomplicated Acute Pyelonephritis

PURPOSE

This study examined the clinical effectiveness of parenteral cefuroxime and cefotaxime as empirical antibiotics for treating hospitalized women with uncomplicated acute pyelonephritis (APN).

MATERIALS AND METHODS

This study was based on the clinical and microbiologic data of 255 hospitalized women with APN. Of these 255 women, 144 patients received cefuroxime and 111 received cefotaxime.

RESULTS

There were no marked differences in the demographic features, clinical characteristics, and treatment duration between the populations of the cefuroxime and cefotaxime groups. The rates of defervescence showed no significant differences in the two groups at 48, 72, 96, and 120 hours. The clinical cure rates observed at the follow-up visit 4 to 14 days after the completion of antimicrobial therapy were not statistically different between the cefuroxime and cefotaxime groups [94.9% (129 of 136) versus 98.0% (100 of 102), respectively; p=0.307], and the microbiological cure rates were also not significantly different [88.3% (91 of 103) versus 95.0% (76 of 80), respectively; p=0.186]. The median hospitalization periods in the cefuroxime and cefotaxime groups were 7 (6-8) and 7 (6-8) days (p=0.157), respectively. Microbiological success rates after 72-96 hours of initial antimicrobial therapy were also not statistically different in the cefuroxime and cefotaxime groups, 89.4% (110 of 123) versus 94.9% (93 of 98; p=0.140).

CONCLUSION

Cefuroxime, a second-generation cephalosporin, is an appropriate antibiotic option for the initial treatment of uncomplicated APN and its efficacy does not differ from cefotaxime, a third-generation cephalosporin, in the initial parenteral therapy for community-onset APN.

Immunogenicity and safety of a cell culture-derived inactivated trivalent influenza vaccine (NBP607): A randomized, double-blind, multi-center, phase 3 clinical trial

BACKGROUND

Cell culture-derived influenza vaccines (CCIVs) have several important advantages over egg-based influenza vaccines, including shorter production time, better preservation of wild-type virus antigenicity and large-scale production capacity.

METHODS

A randomized, double-blind, phase 3 trial was undertaken to evaluate the immunogenicity and safety of a novel cell culture-derived inactivated, subunit, trivalent influenza vaccine (NBP607, SK Chemicals, Seongnam, Korea) compared to the control vaccine (AgrippalS1, Novartis Vaccines and Diagnostics Srl, Siena, Italy) among healthy adults aged 19 years or older (Clinical trial Number-NCT02344134). Immunogenicity was determined at pre-vaccination, 1 month and 6 month post-vaccination by the hemagglutination inhibition assay. Solicited and unsolicited adverse events were assessed after vaccination.

RESULTS

A total of 1156 healthy subjects were recruited. NBP607 met all of the criteria of Committee for Medicinal Products for Human Use (CHMP) at 21 days post-vaccination. Contrary to NBP607, the control vaccine did not satisfy the seroconversion criteria for influenza B irrespective of age. Although the geometric mean titer for each influenza subtype declined gradually, seroprotection rate still remained ≥80% for all subtypes up to six month after NBP607 administration. NBP607 recipients met the seroprotection criteria for all three influenza subtypes up to 6 month post-vaccination. There was no significant difference in the occurrence of adverse events between the NBP607 and control groups.

CONCLUSION

NBP607, a novel CCIV, showed excellent immunogenicity that lasted ≥6 months after vaccination and had tolerable safety profiles. In particular, NBP607 was more immunogenic against influenza B compared to the control, an egg-based subunit vaccine.

A comparison of the clinical characteristics of elderly and non-elderly women with community-onset, non-obstructive acute pyelonephritis

BACKGROUND/AIMS

Acute pyelonephritis (APN) is the most common cause of community-onset bacteremia in hospitalized elderly patients. The objectives of this study were to investigate the differences in the clinical and microbiological data of hospitalized elderly and non-elderly women with community-onset APN.

METHODS

Women with community-onset APN as a discharge diagnosis were identified from January 2004 to December 2013 using an electronic medical records system. We compared the clinical and microbiologic data in elderly and non-elderly women with community-onset APN due to Enterobacteriaceae.

RESULTS

Of the 1,134 women with community-onset APN caused by Enterobacteriaceae, 443 were elderly and 691 were non-elderly women. The elderly group had a lower frequency of upper and lower urinary tract symptoms/signs than the non-elderly. The incidence of bacteremia, extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae, patients with a C-reactive protein (CRP) level ≥ 15 mg/dL, and patients with a leukocyte count ≥ 15,000/mm(3) in the blood, were significantly higher in the elderly group than in the non-elderly group. The proportion of patients requiring hospitalization for 10 days or more was significantly higher in the elderly group compared to the non-elderly group (51.5% vs. 26.2%, p < 0.001). The clinical cure rates at 4 to 14 days after the end of therapy were 98.3% (338/344) and 97.4% (519/533) in the elderly and non-elderly groups, respectively (p = 0.393).

CONCLUSIONS

Elderly women with APN exhibit higher serum CRP levels, a higher frequency of bacteremia, a higher proportion of ESBL-producing uropathogens, and require a longer hospitalization than non-elderly women, although these patients may not complain of typical urinary symptoms.

Phase IV: randomized controlled trial to evaluate lot consistency of trivalent split influenza vaccines in healthy adults

Influenza vaccines are the primary method for preventing influenza and its complications. Considering the increasing demand for influenza vaccines, vaccine manufacturers are required to establish large-scale production systems. This phase IV randomized trial was conducted to evaluate the lot consistency of trivalent split influenza vaccines regarding immunogenicity and safety. A total of 1,023 healthy adults aged 18-64 y were enrolled in the study. Subjects were randomly assigned in a 1:1 ratio to receive the GC FLU® Prefilled Syringe or the GC FLU® Injection, and they were further randomized to one of 3 lots of each vaccine in a 1:1:1 ratio. In both GC FLU® Injection and GC FLU® Prefilled Syringe groups, immune responses were equivalent between lots for each of the 3 vaccine strains on day 21. The 2-sided 95% CI of GMT ratios between pairs of lots were between 0.67 and 1.5, meeting the equivalence criteria. After vaccination, all 3 criteria of the European Medicines Agency were met in both GC FLU® Injection and GC FLU® Prefilled Syringe groups. The vaccines showed tolerable safety profiles without serious adverse events. The demonstration of lot consistency, robust immunogenic responses and favorable safety profiles support the reliability of mass-manufacturing systems for the GC FLU® Injection and GC FLU® Prefilled Syringe.

Spontaneous Pneumomediastinum, Pneumopericardium, and Pneumothorax with Respiratory Failure in a Patient with AIDS and Pneumocystis jirovecii Pneumonia

Spontaneous pneumothorax occurs in up to 35% of patients with Pneumocystis jirovecii pneumonia. However, spontaneous pneumomediastinum and pneumopericardium are uncommon complications in patients infected with human immunodeficiency virus, with no reported incidence rates, even among patients with acquired immunodeficiency syndrome (AIDS) and P. jirovecii pneumonia. We report a case of spontaneous pneumomediastinum, pneumopericardium, and pneumothorax with respiratory failure during treatment of P. jirovecii pneumonia in a patient with AIDS; the P. jirovecii infection was confirmed by performing methenamine silver staining of bronchoalveolar lavage specimens. This case suggests that spontaneous pneumomediastinum and pneumopericardium should be considered in patients with AIDS and P. jirovecii pneumonia.

Susceptibility of Escherichia coli from community-acquired urinary tract infection to fosfomycin, nitrofurantoin, and temocillin in Korea

With increase of multi-drug resistant Escherichia coli in community-acquired urinary tract infections (CA-UTI), other treatment option with a therapeutic efficacy and a low antibiotic selective pressure is necessary. In this study, we evaluated in vitro susceptibility of E. coli isolates from CA-UTI to fosfomycin (FM), nitrofurantoin (NI), temocillin (TMO) as well as trimethoprim-sulfamethoxazole (SMX), ciprofloxacin (CIP) and cefepime (FEP). The minimal inhibitory concentrations were determined by E-test or agar dilution method according to the Clinical and Laboratory Standards Institute guidelines, using 346 E. coli collected in 12 Korean hospitals from March 2010 to February 2011. FM, NI and TMO showed an excellent susceptibility profile; FM 100% (346/346), TMO 96.8% (335/346), and NI 99.4% (344/346). Conversely, resistance rates of CIP and SMX were 22% (76/346) and 29.2% (101/349), respectively. FEP still retained an activity of 98.5%. In Korea, NI and TMO in addition to FM are a good therapeutic option for uncomplicated CA-UTI, especially for lower UTI.

Comparison of the clinical characteristics of diabetic and non-diabetic women with community-acquired acute pyelonephritis: a multicenter study

OBJECTIVES

Purpose of this study was to compare clinical characteristics and treatment outcomes in diabetic and non-diabetic women with community-acquired APN (CA-APN).

METHODS

We prospectively collected and analyzed clinical data of women with CA-APN who attended 11 hospitals in South Korea from March 2010 to February 2012.

RESULTS

Of a total of 775 patients, 246 (31.7%) were diabetic and 529 (68.3%) non-diabetic. Fewer of the diabetic patients had flank pain (27.6% vs. 37.2% P = 0.009), symptoms of lower urinary tract infection (57.3% vs. 69.6% P = 0.001) and costovertebral angle tenderness (54.9% vs. 72.2% P < 0.001). However, more of them had C-reactive protein ≥20 mg/dL (40.7% vs. 27.4% P < 0.001), azotemia (29.3% vs. 13.4% P < 0.001) and bacteremia (53.7% vs. 38.2% P < 0.001). Final clinical failure rates and deaths did not differ between the two groups: 6.9% vs. 4.5%, P = 0.169; 2.0% vs. 1.7%, P = 0.747. However, hospitalization was longer in the diabetics than the non-diabetics (median 9.0 days vs. 7.0 days, P < 0.001). In logistic regression, diabetes was independently associated with longer hospitalization (OR 1.7, CI 1.1-2.7, P = 0.011), together with nausea/vomiting, history of admission within 1 year, bacteremia, azotemia, and dementia, as well as extended-spectrum β-lactamase (ESBL)-positivity and fluoroquinolone resistance of uropathogens.

CONCLUSIONS

CA-APN patients with diabetes have more severe disease manifestations and require longer hospitalization than non-diabetic patients although their clinical findings are less clear than those of non-diabetic patients.

Age- and influenza activity-stratified case definitions of influenza-like illness: experience from hospital-based influenza surveillance in South Korea

OBJECTIVES

This study aims to identify clinical case definitions of influenza with higher accuracy in patients stratified by age group and influenza activity using hospital-based surveillance system.

METHODS

In seven tertiary hospitals across South Korea during 2011-2012 influenza season, respiratory specimens were obtained from patients presenting an influenza-like illness (ILI), defined as having fever plus at least one of following symptoms: cough, sore throat or rhinorrhea. Influenza was confirmed by reverse transcriptase-polymerase chain reaction. We performed multivariate logistic regression analyses to identify clinical variables with better relation with laboratory-confirmed influenza, and compared the accuracy of combinations.

RESULTS

Over the study period, we enrolled 1417 patients, of which 647 had laboratory-confirmed influenza. Patients with cough, rhinorrhea, sore throat or headache were more likely to have influenza (p<0.05). The most accurate criterion across the study population was the combination of cough, rhinorrhea, sore throat and headache (sensitivity 71.3%, specificity 60.1% and AUROC 0.66). The combination of rhinorrhea, sore throat and sputum during the peak influenza activity period in the young age group showed higher accuracy than that using the whole population (sensitivity 89.3%, specificity 72.1%, and AUROC 0.81).

CONCLUSIONS

The accuracy of clinical case definitions of influenza differed across age groups and influenza activity periods. Categorizing the entire population into subgroups would improve the detection of influenza patients in the hospital-based surveillance system.

Clinical courses and outcomes of hospitalized adult patients with seasonal influenza in Korea, 2011-2012: Hospital-based Influenza Morbidity & Mortality (HIMM) surveillance

Influenza is an acute respiratory illness, which can be accompanied by complications such as pneumonia. This study was conducted to survey the clinical courses and outcomes of hospitalized adult patients with laboratory-confirmed seasonal influenza. A prospective case-control study was performed in adult influenza patients who were admitted to hospitals participating in the Hospital-based Influenza Morbidity and Mortality (HIMM) surveillance system in Korea from October 2011 to May 2012. Cases with complicated influenza were compared to those without complications. A total of 123 (5.6%) patients among 2184 laboratory-confirmed adult influenza patients were hospitalized during the 2011-2012 influenza epidemic season. Forty (32.5%) experienced 50 complication episodes. Age older than 60 years (P < 0.01), male sex (P = 0.04), diabetes (P < 0.01), chronic cardiovascular disease (P < 0.01) and neuromuscular disease (P = 0.02) were significantly related to development of complications in univariate analysis. Multivariate logistic regression analysis revealed that diabetes (odds ratio [OR] 3.63, 95% confidence interval [CI] 1.15-11.51, P = 0.02) was an independent risk factor for complicated seasonal influenza. C-reactive protein (CRP) was discriminative between complicated and uncomplicated influenza (cutoff value 13 mg/L, sensitivity 70%, specificity 74%). Complicated patients received antibiotics more frequently (P < 0.01) with longer hospital stays (P = 0.01). In conclusion, diabetic patients are at great risk for complicated influenza, and CRP would be useful to predicting complication. Therefore, early interventions such as antiviral therapy should be considered for high risk patients with diabetes, especially those with increased serum CRP level.

Hospital-based influenza morbidity and mortality surveillance system for influenza-like illnesses: a comparison with national influenza surveillance systems

The Hospital-based Influenza Morbidity and Mortality (HIMM) surveillance system is an emergency room (ER)-based influenza surveillance system in Korea that was established in 2011. The system was established under the assumption that integrated clinical and virologic surveillance could be performed rapidly and easily at seven tertiary hospitals' ER. Here, we assessed the correlation between data generated from the HIMM surveillance system and the Korean national influenza surveillance systems during the 2011-2012 influenza season using cross-correlation analysis and found strong correlations. Rapid antigen-test-based HIMM surveillance would predict the start of influenza epidemic earlier than pre-existing influenza-like-illness-based surveillance.

Hospital-based influenza surveillance in Korea: hospital-based influenza morbidity and mortality study group

Influenza epidemics occur annually with variations in size and severity. Hospital-based Influenza Morbidity & Mortality was established to monitor influenza epidemics and their severity, which is composed of two surveillance systems: emergency room-based and inpatient-based surveillance. Regarding emergency room-based surveillance, influenza-like illness index (influenza-like illness cases per 1,000 emergency room-visiting subjects), number of laboratory-confirmed cases and the distribution of influenza types were estimated weekly. Inpatient-based surveillance included monitoring for hospitalization, complications, and mortality. The emergency room influenza-like illness index correlated well with the number of laboratory-confirmed influenza cases, and showed a bimodal peak at Week 4 (179.2/1,000 emergency room visits) and Weeks 13-14 (169.6/1,000 emergency room visits) of 2012. Influenza A was the predominant strain during the first epidemic peak, while influenza B was isolated exclusively during the second peak. In 2011-2012 season, the mean admission rate of emergency room-visiting patients with influenza-like illness was 16.3% without any increase over the epidemic period. Among the hospitalized patients with influenza, 33.6% (41 out of 122 patients) were accompanied by complications, and pneumonia (28.7%, 35 out of 122 patients) was the most common. Most fatal cases were caused by influenza A (96.2%) after the first epidemic peak. In conclusion, Hospital-based Influenza Morbidity & Mortality was effective for monitoring the trends in circulating influenza activity concurrently with its severity. In the 2011-2012 season, the influenza epidemic persisted for a ≥ 5-month period, with a bimodal peak of influenza A and B in sequence. Overall, influenza A was more severe than influenza B.

HIV downregulates interferon-stimulated genes in primary macrophages

HIV is able to outpace the innate immune response, including that mediated by interferon (IFN), to establish a productive infection. Primary macrophages, however, may be protected from HIV infection by treatment with type I IFN before virus exposure. The ability of HIV to modulate the type I IFN-mediated innate immune response when it encounters a cell that has already been exposed to IFN remains poorly defined. The optimal pretreatment time (12 h) and the most potent HIV-inhibitors (e.g., IFN-α2 and -ω) were identified to investigate the ability of HIV to modulate an established type I IFN response. Gene expression at the level of the entire transcriptome was then compared between primary macrophages treated with type I IFNs, as opposed to treated with IFNs and then infected with HIV. Although HIV was not able to establish a robust infection, the virus was able to downregulate a number of IFN-stimulated genes (ISGs) with a fold change greater than 1.5 (i.e., AXL, IFI27, IFI44, IFI44L, ISG15, OAS1, OAS3, and XAF1). The downregulation of OAS1 by the presence of HIV was confirmed by real-time quantitative polymerase chain reaction. In conclusion, even though HIV replication is significantly inhibited by IFN pretreatment, the virus is able to downregulate the transcription of known antiviral ISGs (e.g., IFI44, ISG15, and OAS1).

Fluoroquinolone resistance in uncomplicated acute pyelonephritis: epidemiology and clinical impact

The objectives of this study were to investigate antibiotic resistance in urinary pathogens from Korean patients with uncomplicated acute pyelonephritis (UAPN), and to determine the effect of fluoroquinolone (FQ) resistance on clinical outcome in those patients with UAPN initially treated with FQ. Clinical and microbiologic data for all the APN patients attending 14 hospitals in South Korea in 2008 were collected retrospectively. Urinary pathogens were identified in 719 cases, and Escherichia coli was the most common pathogen (661/719, 91.9%). Antibiotic susceptibilities to several E. coli antibiotics were as follows: ciprofloxacin, 84.1%; trimethoprim-sulfamethoxazola (TMP-SMX), 67.2%; and extended-spectrum beta-lactamase-negative, 92.4%. FQ was the most frequent antibiotic prescribed for UAPN (45.3% intravenously and 53.9% by mouth). We compared clinical outcomes and hospital days in patients with FQ-resistant (32) and FQ-sensitive E. coli (173) who received FQ as initial empirical therapy. Clinical cure was higher in the FQ-sensitive group (78% vs. 91%, p=0.027), and hospital days were longer in the FQ-resistant group (9.6±5.5 days vs. 7±3.5 days, p=0.001). In conclusion, FQ-sensitivity of E. coli from UAPN was 84.1%. FQ treatment of UAPN caused by FQ-resistant E. coli has a lower cure rate and involves longer hospital stay than FQ treatment of cases caused by FQ-sensitive E. coli.

Immunogenicity and safety of trivalent inactivated influenza vaccine: a randomized, double-blind, multi-center, phase 3 clinical trial in a vaccine-limited country

Influenza vaccines are the primary method for controlling influenza and its complications. This study was conducted as a phase 3, randomized, double-blind, controlled, multi-center trial at seven university hospitals to evaluate the immunogenicity and safety of an inactivated, split, trivalent influenza vaccine (GC501, Green Cross Corporation, Yongin, Korea), which was newly manufactured in Korea in 2008. Between September 21 and 26, a total of 329 healthy subjects were recruited for the immunogenicity analysis, while 976 subjects were enrolled for the safety analysis. The GC501 vaccine met both FDA and EMEA criteria with ≥ 80% of subjects achieving post-vaccination titers ≥ 40 for all three subtypes, even in the elderly. The vaccine was well tolerated with only mild systemic and local adverse events. In summary, GC501 showed excellent immunogenicity and a good safety profile in both young adults and the elderly. The licensure of GC501 might be an important basis in preparation for the future influenza pandemic.

Immunogenicity and safety of influenza A (H1N1) 2009 monovalent inactivated split vaccine in Korea

In a pandemic, the development of an effective influenza vaccine is the most important subject from the view of public health. This study was performed to evaluate the immunogenicity and safety of inactivated, monovalent H1N1 2009 vaccine (Green Cross Corporation, Yongin, Korea) among healthy adults aged 19-64 years (Group 1) and the elderly aged ≥ 65 years (Group 2) in a two-dose regimen, 21 days apart. At baseline, 28 of 454 participants (6.1%) had hemagglutination-inhibition titers of ≥ 1:40 with no significant difference between age groups (p=0.27). There was an apparent dose-dependent antibody response; participants receiving the dose of 30 μg hemagglutinin (HA) showed higher geometric mean titers (GMTs) than the 15 μg HA group in both age groups. Despite the rates of seroprotection and seroconversion were significantly higher with 30 μg HA formulation than 15 μg HA formula in Group 2, there was no definite difference in Group 1 irrespective of vaccine formula. Significant GMT elevation after the second dose was not noted in either age group, regardless vaccine formulations. No deaths, vaccine-related serious adverse events, or immediate unsolicited adverse reactions occurred during the study periods.

Infectious complications in living-donor liver transplant recipients: a 9-year single-center experience

BACKGROUND

Infectious complications following living-donor liver transplantation (LDLT) remain a major cause of morbidity and mortality. We analyzed the frequency and type of infectious complications according to the post-transplantation period, and their risk factors with regard to morbidity and mortality.

METHODS

We retrospectively analyzed 208 subjects who had undergone LDLT during a 9-year period.

RESULTS

The rate of infection was 1.69 per patient during the study period. The predominant infections were intra-abdominal infections (37.6%), primary bacteremia (17.4%), and pneumonia (14.5%). Within the first post-transplant month, 140 (39.9%) infections were detected, and catheter-related coagulase-negative staphylococci (44) were the most common infectious agents. During the 2-6-month post-transplant period, 109 infectious episodes occurred (31.1%), and Enterococcus sp. (n=16) related to biliary infection was the most frequent isolate. After the sixth month, 96 infectious episodes (29%) occurred, and biliary tract-related Escherichia coli (n=19) was the major causative organism. The overall mortality was 24.5% (51/208); 1-year survival rate was 88% (196/208). Post-transplant infection-related mortality was 52.9% (27/51). Biliary tract complications, such as biliary stenosis or leakage, significantly increased the mortality (P=0.01); however, reoperation (retransplantation or resurgery for biliary tract obstruction/leakage or to control bleeding) significantly reduced the mortality (P=0.01).

CONCLUSIONS

Our data showed that early catheter removal would mainly aid in reducing infectious complications in the 1-month post-transplantation period. Aggressive management, including reoperation, would lower the mortality in the LDLT recipients.

Comparison of the MicroScan system and the agar dilution assay for Quinupristin/Dalfopristin susceptibility of Enterococcus faecium

We compared the results of Quinupristin/Dalfopristin (Q/D) susceptibility tests by the Positive Combo Panel (Type 11) of the MicroScan Walk Away 96 analyzer (Dade Behring, Inc.) with those obtained by the reference agar dilution method. From September 2003 to August 2004, a total of 410 E. faecium isolates were obtained from clinical samples. Of these, 65 (15.9%) strains were non-susceptible, and 345 (84.1%) strains were susceptible to Q/D. We collected consecutively 65 Q/D non-susceptible E. faecium isolates (42 resistant, 23 intermediate), and randomly selected 32 Q/D susceptible E. faecium isolates using the MicroScan system. The minimal inhibitory concentrations (MICs) of Q/D, vancomycin, and teicoplanin were determined by the agar dilution method according to CLSI guidelines. The agreement rates between the two methods were 100% for Q/D-susceptible strains, 85.7% for Q/D-resistant strains, and 26.1% for Q/D-intermediate strains of E. faecium. The major error rate (S-->R) was 11.9%, and the minor error rate (S-->I) was 13.0%. No very major errors were found. We conclude that for MicroScan 'non-susceptible' test results for Q/D, it is necessary to confirm the result using a reference method. The Q/D-resistance rate was higher in glycopeptide-susceptible (78.0% for vancomycin, 82.0% for teicoplanin) than glycopeptide-resistant E. faecium (22.0% for vancomycin, 16.0% for teicoplanin). Further studies are needed to determine whether Q/D use in hospitals or virginiamycin use in animals, or other factors, are responsible for the high rates of glycopeptide-susceptible and Q/D-resistant E. faecium strains in Korea.

Acute respiratory failure associated with cryptococcal pneumonia and disseminated cryptococcosis in an AIDS patient

A 36-year-old homosexual Mexican man was admitted to our hospital, with a 30-day history of fever and headache. Upon cerebrospinal fluid examination, the patient's white blood cell count was 1,580/L, total protein was 26 mg/dL, sugar was 17 mg/dL, and his intracranial pressure was 23 cmH2O. The patient was diagnosed with HIV (Human Immunodeficiency Virus) infection by serum Western blotting. Cryptococcus neoformans was isolated in cultures of the patient's blood and cerebrospinal fluids. Chest computerized tomography revealed diffuse reticulonodular infiltration and a ground-glass appearance in both perihilar regions, suggestive of either Pneumocystis carinii pneumonia or cryptococcal pneumonia. On the patient's 6th day in our hospital, bronchoalveolar lavage and transbronchial lung biopsy were conducted via bronchoscopy, and a pathologic examination of lung biopsy specimens revealed signs of cryptococcal pneumonia. This patient died on his 14th day in our hospital, as the result of acute respiratory failure, associated with cryptococcal pneumonia and disseminated cryptococcosis.