Infection and Chemotherapy最新文献

Pertussis is endemic worldwide, with epidemics occurring every 2 to 5 years despite a high vaccination coverage. After limited circulation during the coronavirus disease 2019 (COVID-19) pandemic, pertussis cases have increased rapidly worldwide since mid-late 2023, returning to pre-pandemic patterns. In Korea, 90 cases of pertussis were reported from April 2020 to May 2023, with elderly individuals aged ≥65 years accounting for 48.9%. Pertussis cases have increased sharply since June 2024, showing a nationwide epidemic, with a large increase among adolescents aged 13-15 years. As of August 2024, the national incidence rate of pertussis was estimated to be 37.75 per 100,000 population, with the highest incidence of 526.2 per 100,000 population in 13-year-olds. In Europe, during 2023-2024, an increase in pertussis incidence among infants was observed, along with large increases in 10-19-year-olds. In China, the number of reported cases of pertussis has increased rapidly since late 2023, with an age shift to older children, increase of vaccine escape, and a marked increase in the prevalence of macrolide-resistant Bordetella pertussis. The recent global resurgence of pertussis is due to decreased opportunities for boosting immunity by natural infection during the COVID-19 pandemic in combination with waning of immunity-induced pertussis vaccines.

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.

Background: Immunocompromised patients with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection often have prolonged viral shedding, and some are clinically suspected of reinfection with different SARS-CoV-2 variants. However, data on this issue are limited. This study investigated the SARS-CoV-2 variants in serially collected respiratory samples from immunocompromised patients with prolonged viral shedding for over 12 weeks or relapsed viral shedding after at least 2 weeks of viral clearance.

Materials and methods: From February 2022 to September 2023, we prospectively enrolled immunocompromised patients with coronavirus disease 2019 who had hematologic malignancies or had undergone transplantation and were admitted to a tertiary hospital. Weekly saliva or nasopharyngeal swabs were collected from enrolled patients for at least 12 weeks after diagnosis. Genomic RNA polymerase chain reaction (PCR) was performed on samples, and those testing positive underwent viral culture to isolate the live virus. Spike gene full sequencing via Sanger sequencing and real-time reverse transcription-PCR for detecting mutation genes were conducted to identify SARS-CoV-2 variants.

Results: Among 116 enrolled patients, 20 with prolonged or relapsed viral shedding were screened to identify the variants. Of these 20 patients, 7 (35%) exhibited evidence of re-infection; one of 8 patients with prolonged viral shedding and 6 of 12 with relapsed viral shedding were reinfected with SARS-CoV-2.

Conclusion: Our data suggest that approximately one-third of immunocompromised patients with persistent or relapsed viral shedding had reinfection with different variants of SARS-CoV-2.

Background: Carbapenem-resistant Acinetobacter baumannii (CRAB) represents a devastating and growing global threat, calling for new antibiotic treatments. In Korea, the challenge of treating CRAB is compounded by high nosocomial acquisition rates and limited availability of novel antibiotics. Minocycline, a semisynthetic tetracycline derivative, has been proposed as a therapeutic option for CRAB infections. Nonsusceptibility to minocycline may occur through the efflux pump, TetB. The prevalence of tetB in A. baumannii has increased, along with higher minocycline minimum inhibitory concentrations (MICs). We aimed to evaluate minocycline susceptibility rates in clinical strains of CRAB, and the association between tetB carriage and minocycline susceptibility across different genotypes.

Materials and methods: Representative CRAB blood isolates were collected from Asan Medical Center, Seoul. Minocycline susceptibility was assessed using the Clinical and Laboratory Standards Institute (CLSI) breakpoint (≤4 mg/L) and the proposed pharmacokinetics (PK)/pharmacodynamics (PD) breakpoint (≤1 mg/L). Tigecycline was used as a comparator, and its susceptibility breakpoint for Enterobacterales defined by EUCAST was applied (≤0.5 mg/L). The presence of tetB was detected by PCR, and multilocus sequence typing (MLST) was performed using seven housekeeping genes.

Results: Of the 160 CRAB blood isolates, 83.8% were susceptible to minocycline by the CLSI criteria, and 50.6% were PK-PD susceptible by the PK-PD criteria. The minocycline minimum inhibitory concentration (MIC)₅₀/MIC₉₀ was 1/8 mg/L. tetB was present in 49% of isolates and was associated with a higher minocycline MIC (MIC₅₀_/₉₀ 2/8 mg/L vs. 1/2 mg/L). No clear correlation was observed between tetB positivity and tigecycline MIC. Nine MLSTs were identified, with significant differences in tetB carriage rates between the major sequence types. Notably, ST191, associated with non-tetB carriage and greater susceptibility to minocycline, declined over the study period (P=0.004), while ST451, associated with tetB carriage, increased.

Conclusion: tetB was present in 49% of CRAB isolates and was associated with higher MICs and non-susceptibility by both CLSI and PK-PD criteria. However, absence of tetB was not a reliable predictor of minocycline PK-PD susceptibility. Additionally, shifts over time towards genotypes with reduced minocycline susceptibility were observed. Further research is needed to correlate these findings with clinical outcomes and identify additional resistance mechanisms.

Background: The World Health Organization has declared the end of the coronavirus disease 2019 (COVID-19) public health emergency. However, this did not indicate the end of COVID-19. Several months after the infection, numerous patients complain of respiratory or nonspecific symptoms; this condition is called long COVID. Even patients with mild COVID-19 can experience long COVID, thus the burden of long COVID remains considerable. Therefore, we conducted this study to comprehensively analyze the effects of long COVID using multi-faceted assessments.

Materials and methods: We conducted a prospective cohort study involving patients diagnosed with COVID-19 between February 2020 and September 2021 in six tertiary hospitals in Korea. Patients were followed up at 1, 3, 6, 12, 18, and 24 months after discharge. Long COVID was defined as the persistence of three or more COVID-19-related symptoms. The primary outcome of this study was the prevalence of long COVID after the period of COVID-19.

Results: During the study period, 290 patients were enrolled. Among them, 54.5 and 34.6% experienced long COVID within 6 months and after more than 18 months, respectively. Several patients showed abnormal results when tested for post-traumatic stress disorder (17.4%) and anxiety (31.9%) after 18 months. In patients who underwent follow-up chest computed tomography 18 months after COVID-19, abnormal findings remained at 51.9%. Males (odds ratio [OR], 0.17; 95% confidence interval [CI], 0.05-0.53; P=0.004) and elderly (OR, 1.04; 95% CI, 1.00-1.09; P=0.04) showed a significant association with long COVID after 12-18 months in a multivariable logistic regression analysis.

Conclusion: Many patients still showed long COVID after 18 months post SARS-CoV-2 infection. When managing these patients, the assessment of multiple aspects is necessary.

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.

The goals of antimicrobial treatment of end-of-life (EOL) infections are variously defined, raising complex questions about the management futility, ethical aspects, psychosocial burden, and the risk of emerging antimicrobial resistance. The author searched PubMed, Scopus, and Web of Science databases to retrieve relevant articles published from May 1, 2000, to April 30, 2024, on EOL infections and emerging multidrug-resistant organisms. The titles and abstracts of retrieved articles were screened, duplicate records were excluded, and the eligibility of selected papers was assessed. Sixty-one articles were included; the prevalence of EOL infections and antimicrobial therapy were calculated, the common sites and characteristics of EOL infections were identified, and the extent of emerging multidrug-resistant organisms among EOL patients, especially the "superbugs" ones, were estimated. The review indicates that infections are common in terminally ill patients, the prevalence of irrational antimicrobial prescriptions is high globally, with antimicrobials frequently administered until death. Limited data regarding antimicrobial resistance are available, and they cover short periods, while many of those patients survive longer with modern healthcare and become an essential reservoir for emerging multidrug-resistant organisms. This underscores the importance of antimicrobial stewardship programs and the urgent need for further research in this often-overlooked study area.

Background: Chronic suppurative otitis media (CSOM) has caused many hearing disorder cases in developing countries. Inappropriate antibiotic use resulted in a shift of bacterial resistance. The biofilm-forming bacteria, like Pseudomonas aeruginosa, was a common germ detected in CSOM that contributed to a poor prognosis. This study aimed to investigate the bacterial pattern from samples taken from CSOM patients regarding its antibiotic susceptibility and the antibiofilm activity of acetic acid against P. aeruginosa.

Materials and methods: Sterile swabs of forty-five patients with CSOM were collected, followed by isolation of bacterial pathogens, identification, and evaluation of antibiotic sensitivity using modified Kirby Bauer disc diffusion protocol. In vitro testing was done by adding acetic acid to P. aeruginosa culture to gauge the minimum concentration of biofilm inhibition and eradication. They were conducted using the microtiter plate assay method and quantified with an ELISA reader. The data were analyzed statistically using One-Way ANOVA and Tukey Honestly Significant Difference post hoc test.

Results: The samples obtained from 31 of 45 CSOM patients showed positive microbial growth; 26 (57.78%) had a monomicrobial pattern, and 5 (11.11%) had a polymicrobial pattern. The researcher ascertained that 24 isolates, representing 66.67%, were gram-negative bacteria, with P.-aeruginosa identified as the predominant species. P. aeruginosa isolates were sensitive to several antibiotics, including meropenem, amikacin, piperacillin-tazobactam, ceftazidime, and cefoperazone-sulbactam with a rate of 93.33%. The minimum concentration of acetic acid required to qualify as the minimum biofilm inhibitory concentration (MBIC) was determined to be 0.16%, yielding an inhibition rate of 26.79%. A concentration of 0.31% was identified as the minimum biofilm eradication concentration (MBEC), achieving an eradication rate of 77.27%.

Conclusion: P. aeruginosa, the most common bacteria found in CSOM samples, was sensitive to imipenem, amikacin, piperacillin-tazobactam, ceftazidime, and cefoperazone-sulbactam. Acetic acid suppresses P. aeruginosa bacterial biofilm formation at MBIC of 0.16% and MBEC of 0.31%.

Cytomegalovirus (CMV) is a significant concern for patients with allogeneic hematopoietic cell transplantation (allo-HCT). CMV management differs between institutions due to the lack of local guidelines. Here, we describe a case of refractory/resistant CMV infection treated using our institution's CMV management protocol. A 59-year-old woman who underwent allo-HCT was treated for CMV reactivation. Despite 3 months of valganciclovir administration, serum CMV level surged. CMV gene mutation test revealed a ganciclovir-resistant A594V mutation in the UL97 gene. Treatment was switched to foscarnet until the drug became unavailable nationwide. During the foscarnet shortage, cidofovir was used, leading to a decline in CMV levels when foscarnet was reintroduced and used for 2 months. Following allo-HCT, CMV prophylaxis with letermovir is crucial to prevent reactivation in seropositive recipients. CMV titers should be monitored frequently after allo-HCT. The cutoff value for preemptive therapy varies across institutions, with ganciclovir/valganciclovir usually administered as first-line therapy. Maribavir is an option in cases of ganciclovir/valganciclovir resistance or intolerance. CMV gene mutations should be examined in patients with suspected resistance after 2 weeks of appropriate treatment. This case was discussed at the Clinical Grand Round of the Annual Conference of the Korean Society of Infectious Diseases on November 2, 2023.