Infection and Drug Resistance最新文献

Purpose: To systematically analyse and identify volatile organic compounds (VOCs) released by clinical Klebsiella pneumoniae (K. pneumoniae) during growth via proton transfer reaction-mass spectrometry (PTR-MS), aiming to establish a rapid and accurate method for differentiating and identifying carbapenem-resistant Klebsiella pneumoniae (CRKP) and KPC and NDM producers.

Methods: Nonrepetitive clinical strains isolated from patient specimens were collected from September 2021 to May 2025. The strains were subjected to drug susceptibility testing and carbapenemase genotype identification via the VITEK2 system and polymerase chain reaction (PCR). The clinical strains were incubated in a closed system under the combined pressure of meropenem (MEM) and carbapenemase inhibitors for 3 h. PTR-MS was used to monitor the inhibition rate of the characteristic VOC ion signal intensity to obtain drug susceptibility information of KP and carbapenemase type. Characteristic ions were characterized via fast gas chromatography (FGC)-PTR-MS.

Results: A total of 105 clinical isolates, including 53 carbapenem-susceptible Klebsiella pneumoniae (CSKP) isolates and 52 CRKP (43 KPC-positive and 9 NDM-positive) isolates, were collected. With MEM, the sensitivity and specificity of PTR-MS for monitoring CRKP were 98.08% and 100.00%, respectively. In the case of MEM combined with different carbapenemase inhibitors, the assay was evaluated using a subset of isolates (n=31), comprising 22 KPC-positive and 9 NDM-positive strains. The sensitivity and specificity of PTR-MS for monitoring single KPC producers were 90.91% and 100.00%, respectively, and those for single NDM producers were 88.89% and 100.00%, respectively (kappa= 0.853 and 0.919 for KPC- and NDM-positive strains, respectively). FGC-PTR-MS analysis indicated that the VOCs corresponding to these characteristic ions were acetaldehyde, ethanol and acetic acid.

Conclusion: Real-time monitoring by PTR-MS of the dynamic release characteristics of specific VOC ions in the headspace of CRKP within 3 h under the combined stress of antibiotics and carbapenemase inhibitors can provide important information for rapidly identifying CRKP and the main clinical carbapenemase types.

Purpose: HIV drug resistance is increasing globally, especially in resource-limited settings. NNRTIs, commonly used as first-line ART, have a low genetic barrier and are prone to resistance mutations. Lifelong ART contributes to the accumulation of drug resistance mutations (DRMs), compromising treatment efficacy. Genotypic resistance testing is essential before initiating or modifying ART. However, the Sanger sequencing method relies on successful PCR amplification, which is often suboptimal in low viral load (VL) samples, limiting sensitivity and coverage.

Patients and methods: We developed an optimized primer system targeting conserved regions in the protease (PR), reverse transcriptase (RT), and integrase (IN) genes, covering PR aa 1-99, RT aa 1-410 (including NNRTI resistance sites Y318 and N348), and IN aa 1-288. A total of 2,071 HIV-positive plasma samples collected in China (Jan 2023-Dec 2024) were analyzed using a PCR-Sanger sequencing method. Subtyping was performed using BLAST, COMET 2.4, and the HIV-1 Gene Sequences Database (China). Amplification success rates and mutation detection were evaluated across VL levels.

Results: The overall amplification success rates were 87.40% (1,810/2,071) for the PR/RT region and 87.06% (1,803/2,071) for the IN region. In samples with VLs of 50-200 copies/mL, the success rates remained above 80% for PR/RT and 78.10% for IN. For samples with VL ≥1000 copies/mL, both regions achieved amplification rates above 99%. Among eight samples harboring Y318 or N348 mutations, all were successfully amplified at 1000, 400, 200, and 100 copies/mL. Three of them consistently yielded detectable mutations across all gradients. Subtyping revealed CRF01_AE and CRF07_BC as the predominant strains, consistent with national epidemiological trends.

Conclusion: The optimized system improves amplification sensitivity and mutation coverage, especially in low-VL samples. It enables stable detection of key NNRTI resistance mutations and shows strong subtype compatibility, supporting its utility in clinical resistance surveillance and early detection.

Objective: To establish a predictive model for wound infection after ileostomy for rectal cancer and its relationship with nucleotide-binding oligomerisation domain-like receptor thermal protein domain-associated protein 3 (NLRP3) gene polymorphism.

Methods: A total of 347 samples were randomly divided into two groups: the model group (n = 260) and the verification group (n = 87). The patients in the model group were further divided into the infection group (n = 96) and the non-infection group (n = 164). Multivariate logistic regression was used to analyse the influencing factors of postoperative infection. The TaqMan probe method was used for genotyping.

Results: The results of multivariate logistic regression analysis showed that age >65 years, diabetes, operation time >105 minutes, loop colostomy and abnormal transepidermal water loss (TEWL) were independent risk factors. The risk value of postoperative wound infection predicted by the nomogram model reached 0.93, corresponding to a maximum predicted infection probability of 92.68%. The area under the receiver operating characteristic curve for the nomogram model was 0.869 (P < 0.001) and 0.861 (P < 0.001). The comparison of NLRP3 genotypes between the two groups showed that the proportion of the GG genotype was significantly higher in the infection group than the CC and CG genotypes (51.43% vs 29.90% and 38.98%, respectively). In patients with the GG genotype, the associations between age >65 years, diabetes and abnormal TEWL with wound infection remained significant (all P < 0.05), indicating that these clinical risk factors are particularly prevalent among GG carriers.

Conclusion: This study identified the independent risk factors for postoperative wound infection. Patients with the G allele have a higher risk of postoperative infection, and NLRP3 gene polymorphism is closely associated with the risk factors included in the model. The association between NLRP3 gene polymorphisms and the risk of postoperative infection provides a new molecular biological indicator for prognostic evaluation.

Introduction: To characterize the genomic architecture of carbapenemase-producing Pseudomonas juntendi harboring bla _VIM-2, elucidate genetic mechanisms underlying carbapenem resistance, and evaluate mobile genetic element (MGE)-mediated dissemination pathways using Oxford Nanopore and Illumina sequencing were combined for hybrid genome assembly approaches.

Methods: Hybrid Nanopore-Illumina whole-genome sequencing was applied on two P. juntendi isolates (L2353hy/L2891hy) recovered from distinct human fecal samples. L2353hy and L2891hy were identified as P. juntendi by ANI analysis. Comparative pangenomics identified resistance determinants and phylogenetic relationships, and SNP distances were calculated using SNP-dists. Plasmid profiles were verified using S1 nuclease pulsed-field gel electrophoresis (S1-PFGE).

Results: Both strains exhibited a multidrug resistance profile, comprising 13 antimicrobial resistance genes (ARGs), including bla _VIM-2, bla _OXA-246, and tet(A). Core genome phylogeny demonstrated clonal propagation of two VIM-producing P. juntendi strains. Notably, these two isolates were closely linked to P. juntendi yb_3 (a fish intestinal isolate; Wenzhou, China).

Conclusion: This study reports two clonally related P. juntendi strains harboring bla _VIM-2 isolated from human fecal microbiota, expanding the genomic understanding of carbapenem-resistant P. juntendi. The close phylogenetic relationship between these human isolates and an animal-derived strain (P. juntendi yb_3) underscores bidirectional resistance gene flow at the human-animal interface. Our findings support a One Health-oriented surveillance approach to mitigate the dissemination of carbapenemase-producing pathogens.

Purpose: Gut colonization of carbapenem-resistant Enterobacterales (CRE) poses a significant risk for systemic infections, but the mechanisms driving resistance dissemination are poorly understood. This study aimed to investigate whether outer membrane vesicles (OMVs) secreted by gut-colonized CRE can enter the human circulatory system and mediate extracellular antibiotic resistance through functional carbapenemases and resistance genes.

Patients and methods: We conducted comparative proteomic analyses of OMVs isolated from parental CRE strains and patient plasma samples. Antibiotic degradation assays were performed to evaluate OMV-mediated hydrolysis of imipenem and meropenem. In vitro experiments assessed the protective effects of OMVs on carbapenem-susceptible Escherichia coli and Pseudomonas aeruginosa. Additionally, a Galleria mellonella infection model was used to examine OMV-mediated bacterial survival under carbapenem pressure.

Results: Plasma-derived OMVs exhibited proteomic profiles similar to bacterial OMVs, including carbapenemase components, and demonstrated comparable antibiotic-degrading activity. These OMVs hydrolyzed 60-75% of imipenem and meropenem within 24 hours, protecting susceptible bacteria from growth inhibition in vitro. Although no horizontal gene transfer was observed, OMVs enhanced Klebsiella pneumoniae survival under carbapenem pressure in the G. mellonella model, increasing larval survival rates by 25%.

Conclusion: Our findings reveal a novel OMV-mediated extracellular resistance mechanism that operates independently of genetic transfer, promoting bacterial persistence in the bloodstream. This study provides key insights into the role of OMVs in clinical treatment failure and identifies potential therapeutic targets to combat antibiotic resistance dissemination.

From being a curiosity in the 1990s, CTX-M-producing Escherichia coli invaded most parts of the globe during the 2000s and 2010s, with multidrug-resistant (MDR) clone ST131 and CTX-M-15 leading the charge. The most widely distributed CTX-M types, with the highest global frequencies (up to 70% in certain lower- and middle-income countries), are CTX-M-15, CTX-M-14 and CTX-M-27. E. coli isolates with bla _CTX-M-27 are currently emerging globally. The worldwide ascendancy of E. coli with bla _CTX-M genes occurred via the spread of IncF plasmids between isolates and the existence of certain successful clones (eg, ST131) that acted as repositories for these genes. This is an impressive "gene survival strategy" that aided with the endurance of bla _CTX-M in different environments, including the community and hospitals. The detection of extended-spectrum β-lactamase (ESBL)-producing E. coli (including CTX-M isolates) in clinical laboratories is reasonably straightforward. However, different methodologies (eg, immunogenic and genomic) have recently become available to specifically identify CTX-Ms in bacterial isolates as well as human specimens. The role of such tests is currently unclear. E. coli with CTX-M β-lactamases have indirectly been driving the carbapenemase pandemic and are forces to be reckoned with.

Background: In the small non-malignant specimens acquired through respiratory endoscopy, the conventional pathological examination approaches such as acid-fast staining have certain restrictions in the sensitivity of tuberculosis diagnosis.

Objective: To investigate the sensitizing effect and clinical value of polymerase chain reaction for Mycobacterium tuberculosis (TB-PCR) based on fluorescent probe nucleic acid detection technology in improving the diagnostic positive rate of non-malignant small specimens obtained by respiratory endoscopy.

Methods: A retrospective analysis was conducted on 729 patients with suspected TB who underwent respiratory endoscopy. All patients provided small non-malignant specimens for TB-PCR, acid-fast staining, and mycobacterial culture. A clinical composite diagnosis served as the gold standard. Diagnostic performance was assessed by accuracy, sensitivity, specificity, and area under the ROC curve (AUC). A subgroup of 113 patients underwent additional testing (T-SPOT. TB, TB-Ab, BALF-G-Xpert, BALF-TB) for extended comparison.

Results: The AUC, accuracy, sensitivity, specificity, PPV and NPV of TB-PCR in the diagnosis of TB were 0.88 (95% CI: 0.86-0.90), 0.88 (95% CI: 0.85-0.90), 0.99 (95% CI: 0.98-1.00), 0.78 (0.74-0.82), 0.79 (95% CI: 0.75-0.83), 0.99 (95% CI: 0.97-1.00), respectively. Among 729 patients (391 TB+, 338 TB-), TB-PCR showed significantly higher overall diagnostic efficacy (AUC: 0.88) than acid-fast staining (AUC: 0.77, P<0.05) and was comparable to culture (AUC: 0.87). TB-PCR also demonstrated superior accuracy (0.89 vs 0.61-0.85, P<0.05) compared to immunologic and BALF-based tests in the subgroup analysis, achieving nearly perfect sensitivity (0.99-1.00) and high NPV (0.99-1.00).

Conclusion: The application of TB-PCR for the detection of lung samples obtained through respiratory endoscopy holds significant clinical application value in the diagnosis of TB. Clinicians should fully recognize the merits and potential of TB-PCR technology, proactively apply it in clinical practice, and choose appropriate detection methods based on the specific conditions of patients.

Purpose: This study aimed to evaluate the antimicrobial susceptibility and identify genetic determinants of resistance in Vibrio cholerae strains maintained in the culture collection of the Masgut Aikimbayev National Scientific Center for Especially Dangerous Infections (NSCEDI, Republic of Kazakhstan). The analyzed isolates were previously obtained from various environmental and laboratory sources as part of microbiological and epidemiological surveillance conducted between 1970 and 2024.

Methods: Twenty-six V. cholerae isolates representing different serogroups were analyzed using phenotypic and molecular methods. Antimicrobial susceptibility was determined by the Kirby-Bauer disk diffusion test and E-test against 59 antibacterial agents from major pharmacological classes. The presence of resistance genes to β-lactams and glycopeptides was examined using the BacResista GLA Real-Time PCR Detection Kit (DNA-Technology LLC, Moscow, Russia).

Results: All V. cholerae isolates demonstrated high susceptibility to key antibiotics, including doxycycline, ciprofloxacin, tetracycline, cefotaxime, and kanamycin. Sporadic intermediate resistance was observed to nalidixic acid, trimethoprim, and streptomycin. Real-time PCR screening did not detect any β-lactamase or glycopeptide resistance genes among the isolates.

Conclusion: The Vibrio cholerae strains preserved in the NSCEDI collection and isolated during 1970-2024 remain highly susceptible to first-line antibiotics and lack molecular markers of resistance. These findings confirm the continued effectiveness of current antimicrobial regimens for cholera treatment and underscore the importance of ongoing national surveillance of antimicrobial resistance to ensure preparedness and biosafety in potential outbreak situations.

Objective: This study aimed to analyze drug resistance patterns, mutation profiles in Mycobacterium tuberculosis isolates and clinical characteristics of tuberculosis patients in Shaoxing, Zhejiang, China.

Methods: Clinical specimens and data from tuberculosis patients admitted in 2024 were collected. Cultures were established using the MGIT liquid culture system, and drug susceptibility to twelve anti-tuberculosis agents (four first-line and eight second-line) was assessed by the microbroth dilution method. Mutations in the rpoB gene, katG gene, and inhA promoter were identified using a DNA microarray chip assay.

Results: Among 268 Mycobacterium tuberculosis isolates, 62 (23.1%) exhibited resistance to at least one anti-tuberculosis drug. These comprised 21 (7.8%) mono-resistant, 25 (9.3%) poly-resistant, and 16 (6.0%) multidrug-resistant strains, including 3 (1.1%) classified as pre-extensively drug-resistant and 1 (0.4%) as extensively drug-resistant. Among rifampicin-resistant isolates, mutations at codons 531 (47.4%) and 526 (21.1%) of the rpoB gene were most frequent, while the katG Ser315Thr substitution was detected in 44.8% of isoniazid-resistant strains. Compared with primary cases, re-treated patients were more frequently over 50 years of age, exhibited a higher prevalence of pulmonary cavities, and showed significantly elevated rates of drug resistance (P < 0.05).

Conclusion: Our findings indicate that although the overall prevalence of drug-resistant tuberculosis in Shaoxing remains low, the resistance patterns are heterogeneous. These results underscore the need for comprehensive drug susceptibility and genetic testing to guide effective treatment strategies.