Orientia tsutsugamushi causes scrub typhus (tsutsugamushi disease), an acute febrile disease. The infection has been effectively treated with antibiotics since chloramphenicol was introduced. However, occasional reports of treatment failures or delayed responses occur in scrub typhus, and their underlying causes remain poorly understood. This narrative review assesses whether antibiotic antagonism between β-lactam and anti-rickettsial antibiotics delays the resolution of scrub typhus. To address this, we reviewed historical changes in antibiotic use, pitfalls in interpreting study results, in vitro antagonism data, and relevant clinical reports. In subtropical regions, doxycycline and ceftriaxone are frequently used concurrently for the empirical treatment of severe acute undifferentiated fever, targeting scrub typhus and typhoid fever. However, an in vitro study demonstrated that cefotaxime reduces the effects of anti-rickettsial antibiotics, including doxycycline, by at least 25%. This potential antibiotic antagonism may delay fever resolution by 1–5 days, a minor difference often difficult to detect in individual patients. Even when detected, it is frequently misinterpreted as antibiotic resistance or attributed to severe disease or atypical clinical manifestations. Furthermore, this phenomenon may contribute to mortality in cases with life-threatening complications.

We describe a rare case of neonatal varicella from sequential household transmission of varicella-zoster virus. A vaccinated sibling developed herpes zoster before delivery, followed by maternal varicella and neonatal infection at 20 days of life. The infant showed generalized vesiculopustular eruptions with mild respiratory symptoms. Polymerase chain reaction confirmed infection presumed to be caused by the vaccine strain because the sibling had no history of natural varicella and there were no other exposure sources. Intravenous acyclovir was administered with good response. The patient recovered fully. This case reminds clinicians to consider vaccine-strain transmission in families with a non-immune mother.

For infections caused by metallo-β-lactamase (MBL)-producing carbapenem-resistant Enterobacterales (CRE), ceftazidime-avibactam (CZA) alone is inactive because avibactam does not inhibit MBLs. Co-administration with aztreonam can restore activity but requires simultaneous delivery and harmonization of non-aligned renal dose adjustments. Pharmacodynamic (PD) targets for MBL producers may also differ from those for serine β-lactamase producers. This study aimed to define practical CZA plus aztreonam dosing regimens across renal function strata using Monte Carlo simulation. Pharmacokinetic (PK) parameters from infected patients receiving concomitant CZA plus aztreonam were modeled using a one-compartment structure with Chronic Kidney Disease Epidemiology Collaboration renal function as the key covariate. Monte Carlo simulations (n=5,000) evaluated concentration-time profiles during the first 24 hours and at steady state across renal strata. Both conventional and stringent PK/PD targets were assessed. Probability of target attainment (PTA) was estimated at clinically relevant minimal inhibitory concentrations (MICs) for ceftazidime and aztreonam and threshold concentrations (CT 2.5 and 4 mg/L) for avibactam. Joint PTA was defined as the probability of simultaneous attainment of aztreonam and avibactam targets. A ceftazidime Cmin >80 mg/L was applied as a neurotoxicity risk threshold. Across simulations, aztreonam and ceftazidime achieved ≥90% PTA at MIC breakpoints under conventional targets. Avibactam achieved ≥90% PTA only at steady-state CT 2.5 mg/L and failed at 4 mg/L or under stringent targets, reflecting limited avibactam exposure relative to higher PD thresholds. In preserved renal function, q6h regimens provided higher joint PTA than q8h dosing, though neither achieved ≥90% joint PTA under stringent targets. Most regimens in reduced renal function (eGFR ≤90 mL/min) maintained ≥90% joint PTA under conventional targets, while attainment under stringent targets was limited. Neurotoxicity risk (Cmin >80 mg/L) remained low across renal strata. Co-administration of CZA and aztreonam using renal-adjusted doses provides a practical and effective strategy for MBL-CRE infections. This approach ensures high joint PTA attainment while maintaining a low neurotoxicity risk across all renal function strata.

BackgroundPneumococcal conjugate vaccine (PCV) was introduced as a part of national immunization program to prevent invasive pneumococcal diseases in Indonesia in 2022. This study aims to investigate the serotype distribution, antimicrobial susceptibility, and genome profile of Streptococcus pneumoniae isolated from hospitalized patients from different regions in Indonesia prior to PCV introduction in Indonesia.Materials and MethodsS. pneumoniae isolates were collected from blood, cerebrospinal fluid, and pleural fluid samples of hospitalised patients in three major referral hospitals located in Medan (North Sumatera), Semarang (Central Java), and Surabaya (East Java) from 2018—2021. Bacterial isolation and identification followed standard laboratory protocols. Serotyping was performed using conventional multiplex PCR and the Quellung reaction. Antimicrobial susceptibility testing (AST) was conducted by broth microdilution, and whole-genome sequencing (WGS) was carried out using the Illumina platform.ResultsS. pneumoniae isolates were recovered from 32 hospitalized patients. Serotype 19F (21.9%) was the most common followed by serotype 6B (12.5%) and 3 (9.4%). The serotypes of a high proportion of isolates (71.9%; 23/32) were included in the PCV13 vaccine. The majority of non-meningitis S. pneumoniae isolates were resistant to tetracycline (48.1%) followed by trimethoprim-sulfamethoxazole (33.3%), azithromycin and erythromycin (25.9% each), whereas penicillin resistant was found predominantly (60.0%) in meningitis isolates. We found AST and genomic prediction of antimicrobial resistance result was align in this study. We found 9 S. pneumoniae isolates (28.1%) were multidrug-resistant. Sequence type 1464 (n=5) and global pneumococcal sequence cluster 1 (n=7) was predominantly found in this study.ConclusionSerotype 19F were the most common among vaccine-type serotype strains isolated from hospitalized patients prior to PCV introduction in Indonesia.

The impact of Streptococcus pneumoniae coinfection on coronavirus disease 2019 (COVID-19) prognosis remains uncertain. We conducted a retrospective analysis of patients hospitalized with COVID-19 who underwent a pneumococcal urinary antigen (PUA) test to assess its clinical utility. Results showed that PUA-positive patients required more oxygen support, high-flow nasal cannula, and dexamethasone compared to PUA-negative patients. Furthermore, the significantly higher incidence of a National Early Warning Score ≥5 in the PUA-positive group (P<0.001) suggests that a positive PUA test is associated with a severe disease course. However, no significant difference in mortality was observed between the two groups, and antibiotics were used in almost all patients (96.2%). While the PUA test may help guide antibiotic use in COVID-19 patients, its interpretation should be approached with caution.

Pneumocystis jirovecii pneumonia (PJP) is a life-threatening infection commonly observed in immunocompromised patients, necessitating prompt diagnosis and treatment. This review evaluates the diagnostic performance of various tests used for PJP diagnosis through a comprehensive literature review. Additionally, we propose a diagnostic algorithm tailored to non-human immunodeficiency virus immunocompromised patients, considering the specific characteristics of current medical resources in Korea.

Criteria for home management of low-risk febrile neutropenia remain challenging in supportive care. Careful selection of low-risk febrile neutropenic pediatric patients can improve outcomes and decrease complications. In the current study, we implemented a clinical pathway for pediatric patients presenting to the emergency room department with low-risk febrile neutropenia by using strict inclusion criteria. This is a prospective study from December 2021 to September 2022; all patients presented to the emergency room department were screened for pathway evaluation, and risk stratification was performed using a strict checklist. Patients were included if they met the low-risk criteria. Thorough clinical and laboratory assessments were performed on these patients. All patients started oral antibiotics and were instructed about alarming signs. Patients were followed up at the outpatient clinic on days 3 and 7. Two hundred and three patients with 200 episodes of low-risk febrile neutropenia were enrolled; one hundred and ten were males, and 90 were females; underlying hematological malignancies accounted for 54.0%. On day three, 181 patients out of 200 were afebrile for 24 hours (90.0%), and 47.5% were still neutropenic. At day seven, all study patients were afebrile, had recovering counts, and stopped antibiotics regardless of the count. Absolute neutrophil count recovery on day seven was achieved in 95.5% of patients. Our inclusion criteria for patients with low-risk febrile neutropenia proved to be safe without deaths or intensive care unit admission and successful with the lowest admission rate, so it can be used for a stewardship program to avoid unnecessary patient admissions and help healthcare givers to optimize patient allocation and follow-up safely.

Group B Streptococcus (GBS) is a major cause of invasive bacterial diseases, including sepsis, meningitis, and pneumonia, particularly in newborns and infants. Pregnant adults, those with pre-existing conditions, and older adults are particularly susceptible. Ongoing research is focused on developing various vaccines utilizing different antigens, including capsular polysaccharides and alpha-like proteins (Alps). Epidemiological data on these antigens in GBS is essential for predicting the effectiveness of these vaccines. However, no epidemiological studies on Alps genotype have been conducted in Korea. This study aimed to fill this gap by investigating the distribution and characteristics of the alp genotype in domestic clinical strains. We analyzed 386 GBS strains isolated from various clinical specimens between April 2000 and November 2018. The serotype of each strain was initially verified using a slide latex agglutination reaction, then confirmed by polymerase chain reaction to determine the presence of the genes bca, rib, alp1, alp2, alp3, and alp4 associated with Alps. Strains were then classified as invasive or non-invasive based on the type of clinical specimen. The distribution of serotypes and alp genotype was analyzed across these classifications. We analyzed 386 bacterial strains to assess their clinical characteristics, serotypes, and alp genotype distributions. Of these strains, 47.1% (182 strains) were invasive primarily isolated from blood samples (43.3%, 167 strains), whereas non-invasive strains were more frequently isolated from sites such as the vagina and urethra. Serotype III was the most prevalent across both invasive and non-invasive strains, comprising 28.2% (109 strains) of all isolates. Notably, 79.5% (307 strains) of all isolates were encompassed by the hexavalent vaccine (serotype Ia, Ib, II, III, and V) formulations. Furthermore, the rib genotype was the most common, detected in 39.4% (152 strains) of all isolates, with a higher prevalence in non-invasive samples (44.1%, 90 strains). Although the distribution of alp genotypes differed between invasive and non-invasive strains, the proportion of bca and rib was substantial. Therefore, Alp protein vaccine containing Rib and Cα antigens is expected to provide protection against prevalent GBS strains in Korea. Additional epidemiological studies on GBS vaginal colonization in pregnant women and invasive neonatal strains are needed to support early neonatal sepsis prevention in these high-risk groups.