Interim Estimates of 2023–2024Seasonal 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.

Molecular Epidemiology of Ciprofloxacin-Resistant Escherichia coli Isolated from Community-Acquired Urinary Tract Infections in Korea / 감염과화학요법

Background@#Escherichia coli is the predominant causative pathogen for community-acquired urinary tract infections (UTIs), and the increase in fluoroquinolone-resistant E. coli is of great concern in Korea. The objectives of this study were to investigate the genotypic characteristics and molecular epidemiology of ciprofloxacin-resistant (CIP-R) E. coli isolated from community-acquired UTIs in Korea. @*Materials and Methods@#E. coli samples isolated from the blood or urine were collected from patients with community-acquired acute pyelonephritis aged 15 years and more who were admitted to 12 Korean hospitals from 1st April 2010 to 29th February 2012. Phylogenetic typing, multilocus sequence typing, and molecular characterization of β-lactamase and plasmidmediated quinolone resistance determinants were performed for CIP-R E. coli isolates. @*Results@#A total of 569 E. coli isolates were collected, and 122 (21.4%) isolates were CIP-R isolates. The most prevalent sequence type (ST) was ST131 (28.7%, 35/122), followed by ST393 (14.7%, 18/122), ST1193 (13.1%, 16/122), ST38 (9.0%, 11/122), and ST405 (8.2%, 10/122). The antimicrobial resistance rates of ST131 to cefepime (22.9%, 8/35), ST38 to gentamicin (100%, 11/11), and ST405 to cefotaxime (66.7%, 6/9) were significantly higher than the resistance rates of all other STs combined. Notably, 40% (4/10) of ST405 clones produced extendedspectrum β-lactamases and were co-resistant to trimethoprim/sulfamethoxazole. aac(6′)-1b-cr (20%, 7/35) and CTX-M-14 (40%, 4/10) were more frequently observed in ST131 and ST405 compared with other clones, respectively. @*Conclusions@#Among the CIP-R uropathogenic E. coli isolates in this study, ST131, ST38, and ST405 were specifically associated with antimicrobial resistance.

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

Clinical and Laboratory Predictors associated with Complicated Scrub Typhus / 감염과화학요법

BACKGROUND@#Scrub typhus, a mite-borne disease caused by bites of Orientia tsutsugamushi-infected chiggers, is endemic in Asia-Pacific countries. In Korea, it is a seasonal disease prevalent in autumn and one of the important causes of acute undifferentiated febrile illness. The purpose of this study was to identify the risk factors for the prediction of the severe clinical course of scrub typhus and to investigate the differences in the clinical and laboratory findings of hospitalized elderly and non-elderly patients with scrub typhus.@*MATERIALS AND METHODS@#This study retrospectively reviewed the medical records of patients diagnosed with scrub typhus.@*RESULTS@#A total of 710 patients were enrolled and 43.9% of them were elderly patients. The number of patients with complicated scrub typhus was 168 (23.7%) and the most common complication of severe scrub typhus was hepatic dysfunction (10.7%) followed by pneumonia (7.2%), acute kidney injury (4.9%) and shock (2.4%). Blood urea nitrogen ≥20 mg/dL, adenosine deaminase (ADA) ≥100 IU/L, pulmonary edema or pleural effusion, lactate dehydrogenase ≥500 U/L, alkaline phosphatase ≥400 IU/L, ferritin ≥500 ng/mL and absence of skin rash were independently associated with severe scrub typhus. There was no significant difference in the incidence of complicated scrub typhus between elderly and non-elderly patients. Absence of skin rash, pulmonary edema, pleural effusion, serum creatinine ≥1.5 mg/dL, total bilirubin ≥1.5 mg/dL, ADA ≥100 IU/L and ferritin ≥500 ng/mL were significantly associated with a longer hospitalization (≥10 days).@*CONCLUSION@#The several independent predictors of complicated scrub typhus were identified in this study. Absence of skin rash, the increased levels of serum ADA and ferritin were identified as the predictors of complicated scrub typhus, which were also associated with a prolonged hospitalization.

Clinical Practice Guidelines for the Antibiotic Treatment of Community-Acquired Urinary Tract Infections / 감염과화학요법

Urinary tract infections (UTIs) are infectious diseases that commonly occur in communities. Although several international guidelines for the management of UTIs have been available, clinical characteristics, etiology and antimicrobial susceptibility patterns may differ from country to country. This work represents an update of the 2011 Korean guideline for UTIs. The current guideline was developed by the update and adaptation method. This clinical practice guideline provides recommendations for the diagnosis and management of UTIs, including asymptomatic bacteriuria, acute uncomplicated cystitis, acute uncomplicated pyelonephritis, complicated pyelonephritis related to urinary tract obstruction, and acute bacterial prostatitis. This guideline targets community-acquired UTIs occurring among adult patients. Healthcare-associated UTIs, catheter-associated UTIs, and infections in immunocompromised patients were not included in this guideline.

Clinical Practice Guidelines for the Antibiotic Treatment of Community-Acquired Urinary Tract Infections / 감염과화학요법

Urinary tract infections (UTIs) are infectious diseases that commonly occur in communities. Although several international guidelines for the management of UTIs have been available, clinical characteristics, etiology and antimicrobial susceptibility patterns may differ from country to country. This work represents an update of the 2011 Korean guideline for UTIs. The current guideline was developed by the update and adaptation method. This clinical practice guideline provides recommendations for the diagnosis and management of UTIs, including asymptomatic bacteriuria, acute uncomplicated cystitis, acute uncomplicated pyelonephritis, complicated pyelonephritis related to urinary tract obstruction, and acute bacterial prostatitis. This guideline targets community-acquired UTIs occurring among adult patients. Healthcare-associated UTIs, catheter-associated UTIs, and infections in immunocompromised patients were not included in this guideline.

Hospital-based Influenza Morbidity and Mortality (HIMM) Surveillance for A/H7N9 Influenza Virus Infection in Returning Travelers

Since 2013, the Hospital-based Influenza Morbidity and Mortality (HIMM) surveillance system began a H7N9 influenza surveillance scheme for returning travelers in addition to pre-existing emergency room (ER)-based influenza-like illness (ILI) surveillance and severe acute respiratory infection (SARI) surveillance. Although limited to eastern China, avian A/H7N9 influenza virus is considered to have the highest pandemic potential among currently circulating influenza viruses. During the study period between October 1st, 2013 and April 30th, 2016, 11 cases presented with ILI within seven days of travel return. These patients visited China, Hong Kong, or neighboring Southeast Asian countries, but none of them visited a livestock market. Seasonal influenza virus (54.5%, 6 among 11) was the most common cause of ILI among returning travelers, and avian A/H7N9 influenza virus was not detected during the study period.

Usefulness of Blood Cultures and Radiologic Imaging Studies in the Management of Patients with Community-Acquired Acute Pyelonephritis / 감염과화학요법

BACKGROUND: The objective of this study was to examine the usefulness of blood cultures and radiologic imaging studies for developing therapeutic strategies in community-acquired acute pyelonephritis (CA-APN) patients. MATERIALS AND METHODS: We prospectively collected the clinical data of CA-APN patients who visited 11 hospitals from March 2010 to February 2011. RESULTS: Positive urine and blood cultures were obtained in 69.3% (568/820) and 42.7% (277/648), respectively, of a total of 827 CA-APN patients. Blood culture identified the urinary pathogen in 60 of 645 (9.3%) patients for whom both urine and blood cultures were performed; the organisms isolated from urine were inconsistent with those from blood in 11 and only blood cultures were positive in 49 patients. Final clinical failure was more common in the bacteremic patients than the non-bacteremic ones (8.0% vs. 2.7%, P = 0.003), as was hospital mortality (3.6% vs. 0.3%, P = 0.003). Likewise, durations of hospitalization and fever were significantly longer. Bacteremia was independent risk factor for mortality (OR 9.290, 1.145-75.392, P = 0.037). With regard to radiologic studies, the detection rate of APN was 84.4% (445/527) by abdominal computed tomography and 40% (72/180) by abdominal ultrasonography. Eighty-one of 683 patients (11.9%) were found to have renal abscess, perinephric abscess, urolithiasis, hydronephorosis/hydroureter or emphysematous cystitis, which could potentially impact on clinical management. Patients with Pitt score ≥ 1, flank pain or azotemia were significantly more likely to have such structural abnormalities. CONCLUSION: Blood cultures are clinically useful for diagnosis of CA-APN, and bacteremia is predictive factor for hospital mortality. Early radiologic imaging studies should be considered for CA-APN patients with Pitt scores ≥1, flank pain or azotemia.

The Prevalence and Risk Factors of Renal Insufficiency among Korean HIV-Infected Patients: The Korea HIV/AIDS Cohort Study / 감염과화학요법

BACKGROUND: Renal disease is one of the leading causes of morbidity and mortality among people infected with human immunodeficiency virus (HIV). However, there are very few published studies about renal insufficiency in HIV-infected persons in Asia, especially in South Korea. MATERIALS AND METHODS: A cross-sectional study was performed to investigate the prevalence and risk factors of renal insufficiency, defined as <60 mL/min/1.73 m², in subjects in the Korea HIV/AIDS Cohort Study enrolled from 19 institutions between December 2006 and July 2013. Data at entry into the cohort were analyzed. RESULTS: Of 454 enrolled subjects, 24 (5.3%) showed renal insufficiency at entry into the cohort. The mean age of patients in the renal insufficiency group was 5.28 years and the majority were male subjects (91.7%). All the patients were receiving antiretroviral agents, mostly protease inhibitor-based regimens (76.4%), for an average of 19 months. In univariate analysis, older age (P = 0.002), diabetes mellitus (DM) (P = 0.0002), unknown route of transmission (P = 0.007), and taking indinavir (P = 0.0022) were associated with renal insufficiency. In multivariable analysis, older age [odds ratio (OR) 1.07, 95% confidence interval (CI) 1.03–1.12, P = 0.002], DM [OR 3.03, 95% CI 1.17–7.82, P = 0.022], unknown route of transmission [OR 6.15, 95% CI 1.77–21.33, P = 0.004], and taking indinavir [OR 3.07, 95% CI 1.17–8.05, P = 0.023] were independent risk factors of renal insufficiency. CONCLUSION: The prevalence of renal insufficiency in HIV-infected subjects in this study was relatively low, similar to that in other countries. Aging, DM, and taking indinavir were significantly associated with decreased glomerular filtration rate. Furthermore, unknown route of transmission was an independent risk factor, which was interpreted as a reflection of patient compliance. Further studies on the incidence and risk factors of renal insufficiency during HIV infection using follow-up cohort data are necessary.

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 beta-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.

Analysis of Risk Factors for Severe Acute Respiratory Infection and Pneumonia and among Adult Patients with Acute Respiratory Illness during 2011-2014 Influenza Seasons in Korea / 감염과화학요법

BACKGROUND: The World Health Organization recommends the surveillance of influenza-like illness (ILI) and severe acute respiratory infection (SARI) to respond effectively to both seasonal influenza epidemics and pandemics. In Korea, the “Hospital-based Influenza Morbidity and Mortality (HIMM)” surveillance system has been operated to monitor ILI and SARI occurrences. MATERIALS AND METHODS: A multi-center prospective observational study was conducted. Adult patients with acute respiratory infection (ARI) were enrolled during the 2011-12, 2012-2013, and 2013-2014 influenza seasons at the 10 university hospitals using the HIMM surveillance system. With respect to SARI and pneumonia development, risk profiles were analyzed in patients with ARI in Korea. RESULTS: A total of 5,459 cases were eligible for this analysis. Among 5,459 cases with ARI, 2,887 cases (52.9%) were identified that they had influenza infection. Among enrolled cases, 750 cases belonged to the SARI group, while 4,709 cases belonged to the non-SARI group. With respect to pneumonia development, 317 cases were accompanied by pneumonia, and 5,142 cases were not. Multivariate analyses revealed that the following factors were associated with an increased risk of SARI: Old age (≥65 years) (odds ratio [OR] 2.69, 95% confidence interval [CI] 2.2-3.32), chronic heart disease (CHD) (OR 2.24, 95% CI 1.68-2.98), cerebrovascular disease (CVD) (OR 1.49, 95% CI 1.05-2.10), chronic obstructive pulmonary disease (COPD) (OR 2.34, 95% CI 1.48-3.69), asthma (OR 2.33, 95% CI 1.62-3.36), chronic kidney disease (CKD) (OR 2.62, 95% CI 1.73-3.99), chronic liver disease (OR 1.71, 95% CI 1.04-2.81), and autoimmune diseases (OR 2.53, 1.57-4.08). Multivariate analyses revealed that the following factors were independent risk factors for pneumonia development: Old age (≥65 years) (OR 5.71, 95% CI 4.10-7.94), CHD (OR 1.54, 95% CI 1.07-2.22), COPD (OR 2.34, 95% CI 1.48-3.69), asthma (OR 2.33, 95% CI 1.62-3.36), CKD (OR 2.62, 95% CI 1.73-3.99), immunocompromised conditions (OR 3.12, 95% CI 1.47-6.62), and autoimmune diseases (OR 3.35, 95% CI 1.79-6.27). The risk of SARI and pneumonia was increased by the number of concurrent chronic medical conditions. CONCLUSION: The risk of SARI and pneumonia development among adult patient with ARI was significantly increased by the presence or number of concurrent chronic medical conditions in Korea.

Prosthetic knee joint infection due to Listeria monocytogenes bacteremia in a diabetic female

No abstract available.

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.

Intrathoracic kidney with left-sided Bochdalek hernia in a woman with bacteremic acute pyelonephritis due to Escherichia coli

No abstract available.

Clinical significance of Providencia bacteremia or bacteriuria

No abstract available.

Invasive Primary Colonic Aspergillosis in the Immunocompetent Host without Classical Risk Factors

Invasive aspergillosis (IA), generally considered an opportunistic infection in immunocompromised hosts, is associated with high morbidity and mortality. IA commonly occurs in the respiratory tract with isolated reports of aspergillosis infection in the nasal sinuses, central nervous system, skin, liver, and urinary tract. Extra-pulmonary aspergillosis is usually observed in disseminated disease. To date, there are a few studies regarding primary and disseminated gastrointestinal (GI) aspergillosis in immunocompromised hosts. Only a few cases of primary GI aspergillosis in non-immunocompromised hosts have been reported; of these, almost all of them involved the upper GI tract. We describe a very rare case of IA involving the lower GI tract in the patient without classical risk factors that presented as multiple colon perforations and was successfully treated by surgery and antifungal treatment. We also review related literature and discuss the characteristics and risk factors of IA in the immunocompetent hosts without classical risk factors. This case that shows IA should be considered in critically ill patients, and that primary lower GI aspergillosis may also occur in the immunocompetent hosts without classical risk factors.

Erratum: Intrathoracic kidney with left-sided Bochdalek hernia in a woman with bacteremic acute pyelonephritis due to Escherichia coli

In the article cited above, upper part page in title page has an error. Ending page of the article should be 268, not 269.

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 beta-lactamase (ESBL)-producing Enterobacteriaceae, patients with a C-reactive protein (CRP) level > or = 15 mg/dL, and patients with a leukocyte count > or = 15,000/mm3 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.