Annals of Clinical Microbiology and Antimicrobials最新文献

Inborn errors of immunity (IEIs) are a frequently underdiagnosed group of disorders, with infectious complications posing significant clinical challenges. Recognizing atypical presentations of common infections and the presence of rare opportunistic pathogens can be critical in suspecting an underlying IEI. Among the infectious complications, chronic viral infections are particularly difficult to manage due to limited evidence-based guidelines. Intra-host viral evolution in these patients can lead to treatment resistance and the emergence of novel viral strains, raising concerns about their potential role as reservoirs for mutant viruses. Novel pathogens such as Aichivirus have been identified as significant causes of infection in individuals with IEIs. Furthermore, infections such as talaromycosis, tuberculosis, BCG-related disease, leishmaniasis, and melioidosis may be underrecognized in certain groups of patients with IEIs, largely due to differences in geographic exposure and environmental risk factors. The effects of emerging infections, such as mpox and Middle East respiratory syndrome coronavirus, on individuals with IEIs remain largely unknown. Management strategies for infections in this population include vaccinations, immunoglobulin replacement, and antimicrobial prophylaxis. However, newer higher valency conjugate pneumococcal vaccines may limit the utility of traditional pneumococcal polysaccharide vaccines in assessing immune function. While immunoglobulin replacement is cost-effective, it can interfere with serological diagnostics. Additionally, antimicrobial resistance is a growing issue, emphasizing the need for improved empiric antibiotic strategies and research into optimal treatment durations. This review highlights the key challenges faced by infectious disease clinicians in the care of patients with IEIs.

Background: The changes in the vaginal microbiota and potential dysbiosis adjustment strategies in diabetic patients remain inconclusive. This study was designed to investigate the impact of Type 2 diabetes mellitus (T2DM) on the ecological dynamics of the vaginal microbiota in perimenopausal and postmenopausal women, with a focus on microbial community structure and functional homeostasis.

Methods: Vaginal secretion samples from 22 T2DM patients (DM group) and 23 healthy controls (CT group) under perimenopausal and postmenopausal conditions were analyzed via metagenomic sequencing. Alpha diversity (Observe, ACE, Shannon-Weaver, Gini-Simpson indices) and beta diversity (PCoA, NMDS) were assessed. Taxonomic profiling, LEfSe analysis, and co-occurrence network construction were performed to identify differential species and microbial interactions. Neutral community modeling evaluated stochastic vs. deterministic assembly processes.

Results: No significant differences were observed in age (62.22 ± 5.74 vs. 58.23 ± 7.55, p = 0.052) or perimenopausal/ postmenopausal status (3/19 vs. 5/18, p = 0.748) between the DM and CT groups. The DM group exhibited significantly higher alpha diversity (p < 0.05) and distinct beta diversity clustering (p < 0.05), marked by reduced Lactobacillus relative abundance (28.7% in CT vs. 6.3% in DM) and increased abundance of opportunistic pathogenic genera (Klebsiella, Gardnerella, Staphylococcus). LEfSe identified Firmicutes as CT biomarkers, while the relative abundance of Bacteroidetes and Prevotella increased in DM group. Both fasting blood glucose and HbA_1c levels significantly influenced the relative abundance of vaginal Lactobacillus crispatus, Lactobacillus gasseri, and Lactobacillus iners, showing a significant negative correlation. Co-occurrence networks revealed greater complexity and more integrated in the DM group (more triangles, lower modularity, higher node degrees, higher clustering coefficients, p < 0.0001). Neutral modeling indicated stochastic assembly (R² >0.5), with Lactobacillus species and opportunistic pathogens deviating from neutral predictions in DM.

Conclusion: Under perimenopausal and postmenopausal conditions, T2DM disrupts vaginal microbiota homeostasis by diminishing protective Lactobacillus populations and promoting pathogen proliferation.

Over the last twenty years, there has been a global resurgence of infections caused by Treponema pallidum subsp. pallidum (T. pallidum), the bacterium responsible for syphilis. Presently, the T. pallidum IgG chemiluminescence immunoassay (CLIA) and T. pallidum particle agglutination (TPPA) are commonly employed for the investigation of potential syphilis cases through treponemal serological testing. The nontreponemal rapid plasma reagin (RPR) flocculation test is used to assess disease activity and test for cure or reinfection. Despite numerous limitations, RPR remains the best available serological standard for assessing the treatment effectiveness of patients at present. However, this method does not fully meet the requirements for treatment efficacy evaluation in syphilis patients because of the persistence of serofast reactions or spontaneous nontreponemal antibody titre decline. Therefore, a new and effective diagnostic specific marker that can also be used for monitoring treatment efficacy is urgently needed. We investigated the dynamic changes in Tp0971-specific antibodies in New Zealand rabbits via indirect ELISA and evaluated the diagnostic utility and treatment monitoring potential of Tp0971 in syphilis patients through combined ELISA and Western blot (WB) analyses. This study aims to establish a novel biomarker candidate for dual purposes of disease diagnosis and treatment response monitoring, thereby providing clinical references for the development of efficacy evaluation markers. We observed significant temporal dynamics in Tp0971-specific antibody levels and RPR titres between penicillin-treated and untreated New Zealand White rabbits. In the penicillin-treated cohort, both parameters demonstrated early elevation followed by marked late-phase decline (e.g., 30d: A450 nm = 1.217 [IQR: 0.940-1.494], RPR 1:16 [IQR: 1:8-1:32]; 312d: A450 nm = 0.4653 [IQR: 0.154-0.776], RPR negative [IQR: negative-1:2]). In contrast, the untreated group presented paradoxical findings: while late-phase RPR titres tended to decrease, leading to negative conversion, persistent elevation of Tp0971-specific antibodies was maintained throughout the observation period (e.g., 30d: A450 nm = 1.143 [IQR: 0.274-2.013], RPR 1:8 [IQR: 1:4-1:16]; 312d: A450 nm = 0.9317 [IQR: 0.185-2.048], RPR 1:1 [IQR: negative-1:4]). In patient samples, the absorbance of Tp0971-ELISA after treatment was significantly lower than that before treatment, and this difference could be observed within 4-6 months (pretreatment: A450 nm = 2.583 [2.376-2.790]; 4-6 m: A450 nm = 1.135 [0.451-1.819], p < 0.01). Moreover, among the collected RPR-negative primary syphilis and cerebral infarction syphilis or neurosyphilis samples, the Tp0971-ELISA results reached positive rates of 100% and 75%, respectively. In conclusion, Tp0971-ELISA may be used to evaluate the treatment efficacy of syphilis, and it has relatively high diagnostic value in patients with primary syphilis and cerebral infarctio

Background: Hypervirulent Klebsiella pneumoniae (hvKP) infection is characterized by its potential severity and metastatic propensity, underlying the importance to employ bactericidal treatment promptly for infection source control. The aim of this study is to investigate the bactericidal activity of antibacterial combination against hvKP, with a particular focus on whether levofloxacin-based combinations can suppress levofloxacin-induced efflux pump related drug resistance.

Methods: We conducted in vitro antimicrobial susceptibility tests on 12 hvKP clinical isolates and the reference strain NTUH-K2044. Checkerboard assays were conducted to evaluate the combination activity of levofloxacin with amikacin or ceftazidime. Time-kill experiments were performed to determining the bactericidal activities of levofloxacin, amikacin, ceftazidime, and the levofloxacin-based combinations against NTUH-K2044. Additionally, the mechanisms underlying induced quinolone resistance were investigated.

Results: Twelve clinical hvKP isolates were highly susceptible to levofloxacin, amikacin, and ceftazidime. The levofloxacin-amikacin and levofloxacin-ceftazidime combinations both demonstrated antibacterial activities as indifference. Time-kill experiments showed that an eight-fold or lower minimal inhibitory concentration (≤ 8×MIC) of levofloxacin, ≤ 1×MIC of amikacin and of ceftazidime, exhibited bactericidal activity against NTUH-K2044 during the initial 1-4 h with various levels of bacterial counts decreasing followed by regrowth. The regrowth samples had high levofloxacin MICs indicating the occurrence of induced resistance. Real-time PCR and wild-type oqxR complementation demonstrated point mutations in oqxR of NTUH-K2044, resulting in an overexpression of the efflux pump encoding gene of oqxAB. Both the levofloxacin-amikacin and levofloxacin-ceftazidime combinations exhibited bactericidal synergy without bacterial regrowth when they were tested with 2×MIC of levofloxacin combined with either 1/2×MIC of amikacin or 1×MIC of ceftazidime.

Conclusions: These results demonstrated that levofloxacin combined with amikacin or ceftazidime exhibited superior bactericidal activities compared to levofloxacin against hvKP and might prevent levofloxacin-induced resistance related to oqxAB overexpression.

The prevalence of carbapenem-resistant Klebsiella pneumoniae (CRKP) infections has surged in China over the past decade, posing a significant public health concern. However, comprehensive data on CRKP antimicrobial resistance patterns and the impact of the COVID-19 pandemic on these patterns in China remain unclear. We conducted a systematic review of CRKP infections in China, utilizing data from PubMed spanning 2006 to July 2023. We focused on resistance rates of CRKP causing infections, examining variations across time, regions, and age groups, as well as factors contributing to antimicrobial resistance. Our analysis included 68 studies from 19 provinces in China, comprising 1,284 CRKP isolates obtained from 779 patients. The overall mortality rate for CRKP infections in China was 27% (95% CI: 0.14-0.41, I² = 73%, k = 47), with ST11 being the predominant sequence type (Pooled Rate: 80%, 95% CI: 0.67-0.90, I² = 86%, k = 31). Temporal and spatial analyses indicated increased resistance to ciprofloxacin (Random effects model: Q_b = 9.88, df = 1, P < 0.010) and levofloxacin (Random effects model: Q_b = 7.69, df = 1, P < 0.010) during the COVID-19 pandemic. Resistance to chloramphenicol (Random effects model: Q_b = 4.97, df = 1, P = 0.030) and ceftazidime-avibactam (Random effects model: Q_b = 8.58, df = 1, P < 0.010) was lower in southern regions, while tetracycline resistance (Random effects model: Q_b = 9.69, df = 1, P < 0.010) was lower in the north. Higher resistance rates were observed in adults and the elderly. Age and geographic location were key factors associated with antimicrobial resistance. Fourteen out of thirty-five drugs showed a positive correlation with mortality rates, emphasizing their significant impact on CRKP infection mortality. This study underscores the need for targeted interventions to address regional and age-related variations in CRKP resistance and highlights the critical role of antimicrobial resistance in influencing mortality outcomes.

Background: Candidozyma auris is an emerging multidrug-resistant fungal pathogen responsible for nosocomial outbreaks worldwide. In addition to antifungal resistance, its ability to persist in the hospital environment and tolerate commonly used biocides presents a critical challenge for infection control. However, the relationship between biocide tolerance, antifungal resistance, and virulence traits in C. auris remains poorly understood.

Methods: In this study, 47 C. auris Clade 1 isolates were evaluated using phenotypic and genotypic methods. ITS region sequencing was performed using Oxford Nanopore technology. Susceptibility testing was conducted for seven antifungal agents and four biocides using the CLSI reference microdilution method. Virulence factors including biofilm formation, secreted aspartyl proteinase, esterase, caseinase, phospholipase, and hemolysis were assessed.

Results: All isolates were identified as Clade 1. MIC values for antifungals ranged from 0.015 to 64 µg/mL, and for biocides from 0.0078 to 128 mg/L. Fluconazole resistance was found in 31% of isolates, while amphotericin B resistance was 4%; no echinocandin resistance was observed. Biofilm and SAP activity were detected in all isolates; esterase was positive in 87%, and caseinase in 4%. Statistically significant correlations were observed between amphotericin B and isavuconazole MICs (ρ = 0.32, p = 0.028), amphotericin B and triclosan MICs (ρ = 0.35, p = 0.018), and amphotericin B MICs and caseinase activity (ρ = 0.31, p = 0.035). These findings suggest potential phenotypic links between antifungal resistance and specific virulence traits.

Conclusions: This is the first study from Türkiye to evaluate the antifungal and biocide susceptibility alongside virulence characteristics of Clade 1 C. auris. While statistically significant associations were observed, we acknowledge that resistance mechanisms and pathogenicity pathways are distinct. Therefore, these correlations should be interpreted cautiously and warrant further investigation at the molecular level.

Background: Heteroresistance can lead to treatment failure and has brought a rigorous challenge to clinical laboratories for detecting them. The aim of this study was to investigate the potential for tigecycline-susceptible Klebsiella pneumoniae (K. pneumoniae) clinical isolates to develop heteroresistance under antibiotic pressure.

Method: In this study, inducing experiment in vitro was used to acquire tigecycline heteroresistance phenotype. Population analysis profiling was used to confirm heteroresistance. Potential tigecycline heteroresistance mechanism through whole-genome sequencing and quantitative reverse-transcription PCR (qRT-PCR) were explored. Time-kill assay was used to explore the effect of tigecycline monotherapy or combination with other antibiotics.

Result: Two clinically isolated K. pneumonia strains were found to change from tigecycline susceptible to resistance during treatment of tigecycline in vivo. Experimental-evolved tigecycline heteroresistant colonies were successfully obtained by exposing to concentration of tigecycline at usual therapy of tigecycline (serum concentration of 0.1 mg/L). Heteroresistant phenotypes were stable, and the minimal inhibitory concentration sustained at resistant after 7 days serially passed in tigecycline-free medium. Frequency of heteroresistant subpopulation ranged from 7.0 × 10^-7 to 1.41 × 10^-6. Genome sequencing and analysis showed mutations of ramR, acrR and rpsJ could be responsible for the stage from tigecycline susceptible to heteroresistance and further to resistance in K. pneumoniae. Quantitative reverse-transcription PCR analysis revealed that the increased expression of tigecycline resistance genes detected in tigecycline resistant subpopulations might be associated with tigecycline heteroresistance. Time-kill assay showed the impaired efficacy of serum concentrations of 0.1 mg/L tigecycline (50 mg/q12h intravenously [i.v.]) monotherapy on tigecycline susceptible K. pneumoniae. 1 mg/L tigecycline could be effective in preventing susceptible strain but failed on heteroresistance. Combination with other antibiotics which are susceptible to target strains such as tigecycline-polymyxin B and tigecycline-amikacin can effectively inhibit the growth of resistant subpopulations.

Conclusion: The findings reveal the phenomenon where tigecycline may induce resistance in initially susceptible strains during clinical treatment, associated with several mutations of ramR, acrR and rpsJ, resulting in treatment failure. The heteroresistant strains induced by low concentrations of tigecycline in vitro provide a perspective for exploring the molecular mechanisms of tigecycline resistance in K. pneumoniae. Combination with other antibiotics like polymyxin B and amikacin would show synergistic effects in evading regrowth of resistant subpopulations.

Background: This study evaluated the performance of the simultaneous amplification and testing (SAT) assay for detecting common Candida species in vaginal specimens compared with culture (gold standard) at the Obstetrics and Gynecology Hospital of Fudan University from December, 2024 to January, 2025.

Methods: Speimens were analyzed by both Candida culture (with MALDI-TOF MS identification) and the SAT-Candida assay. Discordant results were further confirmed by real-time polymerase chain reaction (RT-PCR) and bidirectional sequencing. A comparative analysis (kappa coefficient) was conducted as well. We assessed the limit of detection, technical specificity, repeatability and the clinical diagnostic effectiveness, including sensitivity, specificity, diagnostic accuracy, positive predictive value (PPV), and negative predictive value (NPV) of SAT-Candida assay.

Results: In our study, among the 472 initially collected specimens, 5 were excluded because the presence of the Candida species were outside the detection spectrum of the SAT-Candida assay. The ages of the rest 467 cases ranged from 13 to 77 years old, and by comparison with SAT-Candida assay and Candida culture, 444 concordant results and 23 discordant results were discovered. After the reconfirmation, the SAT-Candida assay presented a overall sensitivity of 98.7%, specificity of 97.8%, PPV of 97.9%, NPV of 98.7%, and diagnostic accuracy of 98.3% in detecting Candida species. The kappa value between Candida culture and SAT-Candida assay in detecting Candida species was 0.91.

Conclusions: This SAT-Candida assay is acute, highly sensitive, and specific, which can be applied as an optimal diagnostic tool for detecting and identifying common Candida species from vaginal samples of vulvovaginal candidiasis (VVC) suspected patients.

Background: Many rifampicin (RIF)-resistant (RR) tuberculosis (TB) patients remain sensitive to isoniazid (INH), which challenges the strategy of using RR as an instant indicator of multiple-drug resistance tuberculosis (MDR-TB). A molecular test capable of concurrently detecting RIF and INH resistance is urgently needed.

Methods: The performance of a novel rapid molecular test, Innowave MTB/RIF/INH (InnowaveDX) was evaluated prospectively in three tertiary hospitals. Its capability of detecting resistance to RIF and INH was assessed.

Results: In 767 pulmonary tuberculosis (PTB) patients, InnowaveDX showed significantly higher sensitivity than the Xpert MTB/RIF assay (Cepheid, USA) (74.97% versus 68.18%; p = 0.003, χ² = 8.664). This difference was particularly notable in culture-negative PTB cases (52.73% versus 41.29%; p = 0.001, χ² = 10.565). Both tests demonstrated high specificity in 286 non-TB patients. The overall consistency in RIF susceptibility prediction between InnowaveDX and the Xpert assay was 97.3% (505/519). InnowaveDX identified 83.05% (98/118) of INH-resistant cases as predicted by phenotypic drug susceptibility testing (pDST) and 95.45% (105/110) by another molecular method (MeltPro, Zeesan, China) for INH resistance detection on isolates. In addition, InnowaveDX showed a 99.35% consistency (154/155) with katG, inhA, and ahpC sequencing on sputum samples. The consistency rate for MDR-TB prediction between InnowaveDX and pDST was 93.25% (332/356). The accuracy of using RR to predict MDR-TB varied between 64.1 and 80.5%, depending on the reference method.

Conclusion: InnowaveDX is an easy, rapid, and sensitive molecular test for PTB diagnosis that can detect INH and RIF resistance within 3 h, facilitating MDR-TB diagnosis on the first day of hospital admission.

Background: Legionella gormanii (L. gormanii) is an emerging pathogen causing legionellosis, yet it is much less studied than the predominant species, L. pneumophila. Clinical treatment guidelines for legionellosis are primarily based on data from L. pneumophila and recommend macrolides and fluoroquinolones. However, the intrinsic antimicrobial susceptibility of L. gormanii is not well-defined, creating uncertainty about whether these guidelines are directly applicable. Establishing a baseline understanding of its susceptibility patterns is a prerequisite for effective epidemiological surveillance and for identifying non-wild-type resistance. This study aims to address this fundamental knowledge gap by characterizing the in vitro susceptibility profiles of a large collection of environmental L. gormanii isolates.

Methods: This study systematically evaluated the in vitro activity of ten representative antimicrobials against 207 environmental L. gormanii isolates collected in China between 2019 and 2021. Minimum inhibitory concentrations (MICs) were determined by the broth microdilution (BMD) method, and species-specific epidemiological cutoff values (ECOFFs) were established using the ECOFFinder tool.

Results: Most tested agents demonstrated good in vitro activity. Rifampin was the most potent agent, while clarithromycin was the most active macrolide. Conversely, tetracyclines showed limited activity. Comparative analysis revealed that L. gormanii exhibited markedly higher MICs for rifampin (approximately 9.58-fold) than typically reported for L. pneumophila. Species-specific ECOFFs were determined for nine antimicrobials: rifampin (0.016 mg/L); ciprofloxacin, levofloxacin, and clarithromycin (0.063 mg/L); moxifloxacin (0.125 mg/L); erythromycin (0.25 mg/L); azithromycin (0.5 mg/L); trimethoprim-sulfamethoxazole (4 mg/L); and tigecycline (16 mg/L).

Conclusions: This study establishes the first large-scale susceptibility dataset and species-specific ECOFFs for L. gormanii. The findings highlight key inter-species differences in susceptibility, particularly for rifampin, underscoring that treatment paradigms cannot be safely extrapolated from L. pneumophila. These ECOFFs provide a critical tool for surveillance of non-wild-type resistance. However, these data, derived from environmental isolates, are intended for epidemiological and hypothesis-generating purposes and must be supplemented with clinical and pharmacokinetic/pharmacodynamic (PK/PD) studies before informing changes to clinical practice.