Acta microbiologica et immunologica Hungarica最新文献

Tuberculosis (TB) control remains severely challenged in Pakistan, with urban slum populations bearing a disproportionate burden due to pronounced socioeconomic disparities. The emergence of multidrug-resistant TB (MDR-TB) poses a critical public health threat; however, community-level data from these high-transmission settings remain limited, obscuring the true scale of the epidemic. A cross-sectional study involving 3,317 individuals was conducted across the urban slum of six districts in Punjab, Pakistan between June 2024 and May 2025. Sputum samples were analyzed using smear microscopy, GeneXpert MTB/RIF, and comprehensive drug susceptibility testing (DST). Sociodemographic and clinical data were collected to assess potential risk factors. The prevalence of Mycobacterium tuberculosis (MTB) infection confirmed by GeneXpert was 17.0% (564/3,317), significantly higher than the 12.8% detected by smear microscopy. Initial molecular testing identified rifampicin resistance in 40.2% (227/564) of MTB-positive cases, with 39.0% (220/564) fulfilling the criteria for MDR-TB. The MDR-TB burden was markedly higher among retreatment cases (68.1%) compared with new cases (29.8%) and exhibited significant geographic clustering, with prevalence exceeding 53% in Lahore and Kasur. Smoking emerged as the most significant risk factor, observed in 73.8% of MTB-positive individuals (P < 0.001). Among rifampicin-resistant isolates subjected to extended DST, resistance rates were 96.9% for isoniazid, 100% for rifampicin, 46.3% for ofloxacin, 4.4% for amikacin, 22.9% for kanamycin, and 8.4% for capreomycin. The prevalence of MDR-TB in the urban slums of Punjab was alarmingly higher than national and global estimates. These findings necessitate an urgent need for expanded molecular diagnostics, active case-finding, and targeted public health interventions in these marginalized communities. Without immediate and coordinated action, urban slums risk becoming focal points for the accelerated emergence of untreatable TB.

The identification of mutations associated with drug resistance is of paramount importance for the rapid detection of drug-resistant Mycobacterium tuberculosis strains. The objective of this study was to identify the mutations responsible for conferring resistance to rifampicin (RIF) and isoniazid (INH) in M. tuberculosis. A total of 84 drug-resistant M. tuberculosis strains including 41 multidrug-resistant (MDR) strains, 37 INH-resistant, RIF-susceptible strains, and 6 RIF-resistant, INH-susceptible strains were analyzed. The 86 M. tuberculosis strains were isolated from clinical samples, between 2022 and 2023 in Ankara, Turkey. PCR amplification and sequencing of rpoB, katG and inhA genes were performed to detect mutations. In the 47 RIF-resistant strains, the predominant mutation in rpoB was S450L observed in 40 of 47 strains (85%), followed by H445Y detected in two strains (4.3%). The Q432K/P, M434I, D435Y, T444I, H445G, S450W, and S450F mutations were identified in one strain each. The S315T mutation in the katG gene was identified in 60 of the 78 INH-resistant strains (76.9%). The rate of mutation -15C>T in inhA was 29.5% (23/78). Both S315Y and -15C>T mutations were detected in six strains (7.7%). This study provided comprehensive information regarding the genetic background of drug-resistant tuberculosis in terms of prevalent mutations responsible for RIF and INH resistance. These findings contribute to develop more sensitive qPCR tests that target mutations for the rapid detection of drug-resistant TB.

Accurate and rapid identification of carbapenemase-producing Gram-negative bacteria is essential for appropriate antimicrobial therapy and infection control. This study compared the diagnostic performance of two multiplex lateral flow immunoassays, the NG-Test CARBA 5 (NG) and a Colloidal Gold Immunoassay (CGI), for the detection of major carbapenemases in clinical isolates of Klebsiella pneumoniae and Pseudomonas aeruginosa. A total of 100 non-duplicate carbapenem-resistant isolates collected in 2024 were included. An in-house polymerase chain reaction assay targeting blaKPC, blaNDM, blaVIM, blaIMP, and blaOXA-48-like genes served as the reference standard.Overall, the NG assay demonstrated higher sensitivity than the CGI assay, while both tests showed excellent specificity. For OXA-48-like enzymes, both assays exhibited 100% specificity and 89.6% sensitivity. Detection of NDM was more sensitive with NG (96.9%) than with CGI (87.7%), whereas both maintained 100% specificity. For KPC detection, NG achieved 100% sensitivity, while CGI showed a markedly lower sensitivity (73.7%). Diagnostic performance was generally superior in K. pneumoniae compared with P. aeruginosa, and both assays showed reduced sensitivity in isolates co-harboring multiple carbapenemase genes.These findings indicate that although both lateral flow assays are rapid and practical tools for routine laboratory use, their performance may vary depending on the carbapenemase type and local epidemiology. Molecular confirmation remains essential, particularly in settings with a high prevalence of multiple carbapenemase-producing isolates.

The present study aimed to investigate the resistome of four trimethoprim-sulfamethoxazole (SXT)-resistant Stenotrophomonas maltophilia complex (Smc) isolates from Bulgarian hematopoietic stem cell transplantation (HSCT) recipients and to subject them to phylogenomic analysis involving all sul1-positive strains of the identified species with available genomes worldwide. Preliminary identification by MALDI-TOF mass spectrometry determined all four isolates as S. maltophilia. The sources of isolation were stools (SM175, SM176, and SM179) and urine (SM178). SM176 and SM178 also showed high-level levofloxacin resistance. All isolates demonstrated in vitro susceptibility to minocycline and cefiderocol. Whole-genome sequencing (WGS) assigned SM175, SM176, and SM178 as Stenotrophomonas forensis. Two types of class 1 integrons were detected in the four isolates, namely SM175 and SM179 carried empty integrons, whereas SM176 and SM178 carried a gene cassette (3,748 bp in length) consisting of aac6'-Ib-cmlB-blaOXA-9. Alignment against public databases revealed that this cassette has not been found in Stenotrophomonas species so far, but it was present in Pseudomonas aeruginosa and Enterobacterales. Phylogenomic analysis of our assembled sequences, together with all 26 sul1-positive S. maltophilia and S. forensis genomes, indicated that S. maltophilia SM179 was not part of any S. maltophilia cluster. SM175, SM176, and SM178 were closely related (differences of 35-101 SNPs). To the best of our knowledge, this is the first report of SXT-resistant Smc isolates from post-HSCT patients with hematological malignancies in Bulgaria, which presents WGS-based resistome and phylogenomic analyses. We also report on the first sul1-containing S. forensis clinical isolates. Our findings reveal high global heterogeneity of sul1-positive S. maltophilia.

Understanding the long-term determinants of antibody levels against SARS-CoV-2 is crucial for evaluating population immunity and guiding public health strategies. While short- and mid-term immune responses after COVID-19 vaccination have been extensively studied, data on long-term humoral immunity remain limited.This observational study was conducted at G. Gennimatas General Hospital of Thessaloniki, Greece. A total of 104 healthcare workers with varying vaccination and infection histories were included to identify the key factors influencing antibody levels. Participants had received three or more doses of the Pfizer-BioNTech mRNA COVID-19 vaccine (BNT162b2, Comirnaty), except for 11 individuals who had received only two doses. Serum samples were collected three years after the third vaccine dose between October 2024 and November 2024.Antibody levels increased after the second and third vaccine doses and subsequently declined over time. In a multivariable regression analysis adjusting for age, sex, number of vaccine doses, and number of infections, we showed that the most important determinant of antibody levels was the individual-specific time (in days) elapsed since the last immunological event, either vaccination or infection. Other factors, including demographic characteristics and cumulative exposure to the virus or vaccines, had no significant independent effect when accounting for time.These findings suggest that waning immunity is the primary driver of antibody levels, emphasizing the need for periodic booster vaccinations to maintain protection in healthcare workers.

The emergence of carbapenem-resistant Klebsiella pneumoniae (CRKP) poses a significant challenge globally. This study reports on a ceftazidime-avibactam resistant KPC-35 producing K. pneumoniae strain from a patient with cerebral hemorrhage undergoing ceftazidime-avibactam (CZA) treatment. In this study, three K. pneumoniae strains were isolated from blood samples of a patient after intracerebral hemorrhage. Broth microdilution, checkerboard assays, and time-kill assays were employed to evaluate antimicrobial susceptibility and combination regimens. Whole-genome sequencing (WGS) was used to investigate the genetic characteristics of the three K. pneumoniae strains. The results showed that, K. pneumoniae KP29870 strain belonged to ST15, it was KPC-35 positive and exhibited a 16-fold higher minimum inhibitory concentration (MIC) of CZA (32 vs 1-2 mg L-1) but significantly lower MICs of imipenem (2 vs ≥ 16 mg L-1) and meropenem (1 vs ≥ 16 mg L-1), compared to the other two K. pneumoniae strains, that harboured KPC-2. CZA resistant K. pneumoniae remained highly susceptible to aztreonam-avibactam (MIC 0.03/4 mg L-1). The single base mutation (T503C) resulted in the substitution of leucine with proline at Ambler amino acid position 169 (L169P), corresponding to an evolution from blaKPC-2 to blaKPC-35. Checkerboard and time-kill assays demonstrated synergistic antibacterial effects for CZA combined with imipenem, meropenem, or with aztreonam against KPC-35 positive K. pneumoniae. This is the first report in China of a K. pneumoniae ST15 strain harboring blaKPC-35 emerging from a blaKPC-2-positive ancestor during CZA treatment. The new β-lactamase inhibitor combination such as aztreonam-avibactam monotherapy or CZA combined with carbapenems or with aztreonam represents promising treatment strategies against such KPC mutants. We recommend prompt susceptibility testing and KPC genotyping if resistance emergence is suspected during CZA therapy.

In recent years, the presence of microbiota in tumors has been discovered through extensive research, overturning the longstanding belief that "tumors are sterile." Advanced techniques such as 16S rRNA gene sequencing, fecal microbiota transplantation, and the construction of mouse models specific to different tumor types have been utilized to validate the existence of microbiota within various tumors. The intratumoral microbiota significantly influences tumor development by modulating immune responses, mediating inflammatory reactions, and interfering with or enhancing immunotherapy or chemotherapy. For instance, Aspergillus sydowii in lung adenocarcinoma promotes immunosuppression via the Dectin-1/CARD9 pathway, while colibactin-producing Escherichia coli in colorectal cancer facilitates tumor progression through lipid metabolism dysregulation. Moreover, intratumoral microbiota can predict patient prognosis and guide personalized cancer treatment strategies, highlighting their potential as therapeutic targets. This review synthesizes current evidence on the roles of intratumoral microbiota across multiple cancer types and discusses their clinical implications.

The emergence of mupirocin-resistant Staphylococcus aureus strains poses a significant challenge to public health due to limited treatment options and the risk of multidrug resistance. This study aims to investigate the antibiotic susceptibility and molecular characteristics of mupirocin resistant S. aureus isolates. A total of 65 mupirocin-resistant isolates were included in the study. The isolates were characterized using antimicrobial susceptibility testing, biofilm formation assay, staphylococcal cassette chromosome mec typing, multilocus sequence typing, and polymerase chain reaction analysis to detect resistance (mecA, mecC, mupA, erm(A), erm(B), erm(C), tet(M), ant (4')-Ia, aac (6')-Ie/aph (2″), and aph (3')-IIIa) and toxin genes (eta, etb, pvl, and tst). Resistance to mupirocin was observed in 12.5% of the S. aureus isolates collected during the study period. Among the 65 mupirocin-resistant MRSA isolates, 75.4% were classified as HLMUPR and 24.6% as LMUPR. cMLSB and iMLSB phenotypes were identified in 41.5 and 36.9% of the isolates. Our results showed that 49.2, 30.8, and 15.4% of isolates were classified as strong, intermediate, and weak biofilm-forming strains, respectively. Our result revealed that about three-quarters of isolates harbored mecA (100%), tet(M) (76.9%), mupA (75.4%) resistance genes. MLST revealed that the 65 isolates belonged to seven clonal complexes, including CC8 (41.5%), followed by CC22 (20%), CC5 (10.8%), CC30 (10.8%), CC15 (7.7%), CC1 (4.6%) and CC80 (4.6%). The vast majority of S. aureus isolates belonged to CC8/ST239-MRSA (21.5%). Among the 32 strong biofilm producers, the majority (28.1%) belonged to CC8/ST8 MRSA clone. Our result revealed that 39.1% of PVL-positive strains belonged to CC/ST22. The fusidic acid resistance isolates belonged to CC/ST8-MRSA (7.7%), CC8/ST239-MRSA (12.3%), CC/ST22-MRSA (7.7%), and CC30/ST80-MRSA (1.5%) lineages. In conclusion, this study provides valuable insights into the characteristics of mupirocin-resistant S. aureus isolates from Tehran, Iran. The results highlight a high prevalence of HLMUPR in this research. Additionally, the study reveals a diverse genetic landscape, with isolates belonging to various clonal complexes, particularly CC8, CC22, and CC5. The high frequency of biofilm formation and resistance to other antibiotics underscores the need for ongoing surveillance and the development of more effective treatment strategies to combat these multidrug-resistant strains.

Bronchoalveolar lavage (BAL) is a basic diagnostic method for the detection of fungal infections in lung transplant recipients. Aspergillus species are frequently identified, typically by the presence of septate hyphae; however, the visualization of conidia in cytologic preparations is rare. Aspergillosis caused by Aspergillus niger is an uncommon but recognized infectious complication in this patient population.We report on the case of a 60-year-old lung transplant recipient who underwent routine surveillance bronchoscopy eight weeks post-transplantation in August 2025. A substantial amount of adherent secretion was noted at the medial part of the right bronchial anastomosis. Surveillance BAL was performed from the right S8 segment, and cytospin preparations revealed intracellular Aspergillus conidia within alveolar macrophages. Galactomannan antigen assay was negative; however, fungal culture confirmed A. niger after five days.This case highlights the diagnostic value of identifying fungal conidia in BAL cytology, which may facilitate early recognition of invasive fungal infection or fungal colonization potentially leading to invasive disease or facilitate chronic lung allograft dysfunction (CLAD) development.

The gut microbiota has emerged as a critical determinant of antitumor immunity and a potential modulator of responses to immune checkpoint inhibitors (ICIs). Although pre-clinical and clinical studies suggest that specific bacterial taxa may influence both efficacy and immune-related adverse events (irAEs). However, the magnitude and consistency of these associations remain unclear. A systematic search of PubMed, Embase, Web of Science, and the Cochrane Library was conducted through March 2025. Eligible studies evaluated baseline gut microbiota composition, fecal microbiota transplantation (FMT), probiotic/prebiotic interventions, or antibiotic exposure in cancer patients treated with ICIs. Pooled hazard ratios (HRs) for overall survival (OS) and progression-free survival (PFS), and odds ratios (ORs) for response rates and irAEs, were estimated using random-effects models. Across 38 studies involving 5,642 patients were included. Pooled analysis demonstrated that enrichment of Akkermansia muciniphila, Bifidobacterium longum and Faecalibacterium prausnitzii was significantly associated with improved OS (HR 0.62, 95% CI 0.51-0.76) and PFS (HR 0.69, 95% CI 0.55-0.83). Conversely, antibiotic exposure before or during ICI treatment was associated with worse OS (HR 1.84, 95% CI 1.45-2.34). Patients undergoing FMT from responders exhibited higher objective response rates (OR 2.91, 95% CI 1.48-5.73). Microbiota diversity indices were consistently higher in responders than in non-responders. Collectively, gut microbiota composition and its modulation significantly impact the therapeutic efficacy and toxicity profile of ICIs. These findings highlight the translational potential of microbiome-based biomarkers and interventions in optimizing immunotherapy.