Microbial drug resistance最新文献

Objective: The prevalence of carbapenem-resistant Acinetobacter baumannii (CRAb) has been increasing globally. This study aimed to investigate the risk factors, resistance gene profiles, and molecular epidemiology of CRAb bloodstream infections (BSIs) among patients in Xi'an, China, to provide evidence for clinical prevention and targeted treatment.

Methods: We conducted a retrospective study of 139 patients with A. baumannii BSIs. Patients were categorized into a CRAb group (n = 84) and a carbapenem-susceptible A. baumannii (CSAb) group (n = 55). Independent risk factors were identified via multivariate logistic regression analysis. Carbapenemase resistance genes were detected using polymerase chain reaction (PCR), and CRAb isolates were molecularly typed by multilocus sequence typing (MLST).

Results: Multivariate logistic regression analysis identified the following as independent risk factors for CRAb BSIs: inappropriate empirical antimicrobial therapy (OR = 8.620; 95% CI: 2.078-35.751), deep venous catheterization (OR = 12.625; 95% CI: 2.263-70.429), prolonged hospitalization before the onset of BSIs (OR = 1.467; 95% CI: 1.123-1.915), and ICU admission (OR = 4.981; 95% CI: 1.898-13.065). Antimicrobial susceptibility testing showed that CRAb isolates were multidrug-resistant, exhibiting resistance rates exceeding 70% to most common clinical antibiotics, with the exception of tigecycline (5.95% resistance) and colistin (27.38% resistance). All 84 CRAb isolates carried both blaOXA-51-like and blaOXA-23-like genes, while other carbapenemase genes were not detected. MLST identified 7 sequence types (STs), with ST540 (45.24%, 38/84) being the dominant clone. eBURST analysis indicated that the major STs (ST195, ST208, etc.) belonged to the same clonal complex.

Conclusion: Inappropriate empirical antimicrobial therapy, deep venous catheterization, prolonged hospitalization before the onset of BSIs and ICU admission are independent risk factors for CRAb BSIs. The prevalent strains produce OXA-23-like carbapenemase, and molecular typing indicates that the ST540 clone and its related clonal complex are predominant, suggesting potential nosocomial clonal spread.

Background and Objectives: Natural disasters increase the risk of wound infections due to factors such as trauma, invasive interventions, and delayed access to care. This study aimed to assess the epidemiology of health care-associated wound infections in earthquake victims and to identify risk factors for infection development.Method: This study was conducted in a 4,050-bed tertiary-care hospital. Adult hospitalized patients (≥18 years) with trauma-related soft tissue injuries and entrapment history were included. Active health care-associated infection surveillance was implemented. Data were collected using standardized forms. Clinical characteristics and risk factors for wound infection were analyzed.Results: Of 584 patients, 139 (23.8%) developed wound infections. Patients with wound infections had longer entrapment times under rubble (16 vs. 5 hours, p < 0.001), delayed hospital admission (120 vs. 72 hours, p = 0.003), and higher crush syndrome (42.4% vs. 20.0%, p < 0.001) and tissue necrosis (26.6% vs. 9.2%, p < 0.001). In multivariable analysis, prolonged time under rubble (odds ratio [OR]:1.010, 95% confidence interval [CI]:1.002-1.018; p = 0.016), delayed surgical intervention (OR:1.130, 95% CI:1.041-1.227; p = 0.004), and tissue necrosis (OR:2.372, 95% CI:1.260-4.467; p = 0.007) were independently associated with wound infection. Gram-negative bacilli predominated (88.1%) in wound cultures; Acinetobacter spp. (31.5%), Klebsiella spp. (19.0%), and Pseudomonas spp. (18.7%) were the most common pathogens. High carbapenem resistance among Acinetobacter spp. (99%) and substantial carbapenem resistance among Klebsiella spp. (46.1%) were identified.Conclusion: Wound infections were common among earthquake victims and were associated with prolonged entrapment, tissue necrosis, and delayed surgical intervention. The predominance of resistant Gram-negative pathogens underscores the need for early infection control measures, antimicrobial resistance surveillance, and antimicrobial stewardship in disaster settings.

Carbapenem-resistant Enterobacterales (CRE), particularly carbapenemase-producing CRE (CP-CRE) are a growing global threat in health care. Intestinal colonization increases infection risk and facilitates transmission in the hospital. We aimed to determine intestinal colonization of CRE and CP-CRE among hospitalized patients in Addis Ababa, Ethiopia. A longitudinal study was conducted on 165 patients from February 2023 to April 2024 at Tikur Anbessa Specialized Hospital. Microbial identification and antimicrobial susceptibility testing were done using VITEK 2. Carbapenemase production was confirmed using the modified carbapenem inactivation method, and Polymerase Chain Reaction (PCR) was used to detect carbapemase genes. CRE colonization was detected in 19.4% of patients at admission and 18.8% during follow-up, showing no significant change (p = 0.65). CP-CRE colonization was increased from 10.3% at admission to 16.4% (p = 0.03) during follow-up. The most frequently identified genes were bla_NDM (71.0%) and bla_OXA-48 (53.0%) at admission. These genes were detected in (74.1%) and (48.1%) during follow-up, respectively. A substantial burden of CRE and CP-CRE colonization was found, with a high persistence rate. Screening high-risk patients and strengthening infection prevention measures are urgently needed.

Extensively drug-resistant Klebsiella pneumoniae (XDR-KP) poses a major global health threat due to limited treatment options and high mortality. While the genomes of carbapenemase-positive XDR-KP strains are well-documented, there is limited data on carbapenemase-negative XDR-KP. This study characterized the genomes of two such clinical isolates, obtained from abdominal fluid and urine, that were resistant to nearly all tested antibiotics. Antimicrobial susceptibility testing was performed at the Hamilton Regional Microbiology Laboratory, ON. Carbapenemase production and the presence of carbapenemase genes were assessed using the NG-Test^®CARBA-5 and a multiplex carbapenemase PCR assay, respectively. Whole-genome sequencing via Oxford Nanopore technology revealed that both strains lacked carbapenemase genes but harbored multiple other resistance genes (e.g., bla_CTX-M-15, qnrB1/S1, sul1/2, dfrA17/A14, fosA) and acrR mutations. Notably, both carried ompK37 mutations, an outer membrane porin previously linked to carbapenem resistance. A number of antibiotic resistance genes were found on conjugative plasmids (IncFIB/IncFII, IncFIA, IncFIA/IncFII). Multilocus sequence typing identified different sequence types (ST307, ST45) and virulence profiling showed overlapping and distinct features, including variability in capsular and siderophore genes. These findings suggest a significant role for porin loss and efflux pump regulation in conferring resistance to broad-spectrum and last-resort antibiotics in clinical XDR-KP isolates that lack carbapenemases and other related antibiotic resistance genes.

Backgrounds: This study aimed to determine beta-lactamase genes, clonal relationships, and the prevalence of the E.coli sequence type 131 (ST131) clone in extended-spectrum beta-lactamase (ESBL)-producing E.coli (ESBL-Ec) strains isolated from community fecal samples.

Methods: A total of 161 fecal samples were collected from healthy individuals and outpatients at Sivas Cumhuriyet University Hospital. ESBL-Ec isolates obtained from these samples were analyzed. Antimicrobial susceptibility was determined by the disc diffusion method following EUCAST guidelines. The presence of blaTEM, blaSHV, blaCTX-M, blaOXA, blaPER, blaVEB, and blaGES genes was investigated by multiplex PCR. The ST131 clone was detected by PCR and Multi Locus Sequence Typing analyses. Clonal relatedness among ESBL-Ec strains was evaluated using ERIC-PCR.

Results: The fecal ESBL-Ec carriage rate was 31.05%. Resistance rates to ciprofloxacin, trimethoprim-sulfamethoxazole, gentamicin, amikacin, and ertapenem were 38%, 58%, 14%, 6%, and 4%, respectively. ESBL genes were detected at rates of blaTEM 82%, blaCTX-M 68%, and blaOXA 10%. ESBL-Ec isolates were grouped into 15 clusters, and 5 (10%) of 50 isolates were identified as the ST131 clone.

Conclusion: This first study in Sivas, Türkiye, shows a high fecal carriage rate of ESBL-Ec and the presence of the E.coli ST131 clone.

Oral and maxillofacial space infections (OMSIs) are potentially life-threatening polymicrobial conditions requiring timely and appropriate antimicrobial therapy. We conducted a systematic review and meta-analysis of 53 studies (12,408 cases) to evaluate microbial epidemiology and resistance patterns. Streptococcus was the predominant pathogen (45.51%), followed by Prevotella (15.89%) and Porphyromonas (15.61%). Methicillin-resistant Staphylococcus aureus (MRSA) accounted for 19.18% of S. aureus isolates. Diabetic patients exhibited a higher prevalence of Klebsiella (27.09% vs. 8.13% in nondiabetics). Antimicrobial resistance was lowest for levofloxacin (11.03%) and cephalosporins (16.83%), and highest for gentamicin (39.66%) and erythromycin (39.35%). The microbiological landscape and antimicrobial resistance patterns were influenced by multiple factors, including infection source, diabetic status, diagnostic methods, national income level, and temporal trends. Incorporating these variables with local antimicrobial surveillance data can support more targeted and effective empirical therapy. Well-designed, representative studies across diverse settings are urgently needed to optimize antimicrobial use amid rising resistance.

The drug-resistant profile of tuberculosis (TB) varies across geological regions. This study aimed to evaluate the association of katG, inhA, and AhpC mutations with isoniazid (INH) resistance of Mycobacterium tuberculosis in pulmonary TB patients from Nanjing, China. Laboratory and genetic data of INH-resistant genes in TB patients living in Nanjing and hospitalized in the Department of Tuberculosis, the Second Hospital of Nanjing, from January 2019 to December 2021 were retrospectively analyzed. A total of 1,712 human M. tuberculosis strains (1,308 INH-sensitive and 404 INH-resistant) were identified by phenotypic drug susceptibility testing (DST). Mutations were detected in katG315, the inhA promoter region, and the AhpC promoter region. Among the 172 INH-resistant strains identified by phenotypic DST, 159 samples of gene mutations were detected. The mutation rate in katG315 in INH-resistant strains was significantly higher than those in the inhA promoter region and AhpC promoter region. The rate of INH resistance was higher in M. tuberculosis strains with the katG315 mutation combined with the inhA/AhpC promoter region mutations than in those with a single mutation in katG315. The incidence of the katG315 mutation in multidrug-resistant TB patients and pre-extensively drug-resistant (pre XDR) TB patients was significantly higher than that in INH-resistant TB patients. The rate of katG315 mutation combined with the inhA/AhpC promoter region mutation was higher in pre XDR-TB patients. The katG315 mutation, or its combination with inhA/AhpC promoter region mutations, may be the main cause of INH resistance of M. tuberculosis strains in TB patients from Nanjing, China.

Background and objective: Drug-resistant (DR) mycobacterial infections present escalating threats in Iran, where facility-specific transmission dynamics and demographic disparities remain poorly characterized. This study evaluated the epidemiology of DR Mycobacterium tuberculosis and pulmonary nontuberculous mycobacterial disease over a 9-year period (2016-2024).

Materials and methods: This retrospective study analyzed 21,700 molecular and culture-confirmed mycobacterial samples. Species identification used line probe assays and Xpert Mycobacterium tuberculosis/rifampin. Drug susceptibility testing followed World Health Organization standards. Statistical analyses identified associations between resistance patterns, hospital sections, gender, and specimen types.

Results: MDR-TB prevalence surged from 0.35% (2017) to 3.27% (2022), peaking during pandemic disruptions. M. simiae dominated nontuberculous mycobacteria (NTM) resistance (55.63% of resistant isolates), with significant increases in 2024 (7.91%). Airborne infection isolation rooms (AIIRs) paradoxically harbored 18.22% of Multidrug-resistant tuberculosis (MDR-TB)isolates (p < 0.0001), while pulmonary medicine units contained zoonotic M. bovis reservoirs (0.27% MDR prevalence). Male patients carried higher burdens of MDR-TB (26.01% vs. 12.45%, p = 0.005) and M. kansasii (2.05% vs. 0.53%, p = 0.012). Diagnostic challenges included 38.14% smear-negative M. abscessus and gastrointestinal NTMs (M. genavense 66.66%). Sample type analysis revealed M. fortuitum in 25.0% of abscesses (p < 0.05) and M. chelonae in 5.55% of synovial fluid (SF) specimens.

Conclusion: Iran faces converging epidemics of MDR-TB and climate-adapted NTMs concentrated in hospital hotspots, with significant gender disparities. Precision interventions targeting AIIR protocols, water safety regulations, and gender-specific screening are urgently needed.

Background: The increasing prevalence of multidrug-resistant Pseudomonas aeruginosa limits treatment options and highlights the need for new antimicrobials. Although agents such as ceftazidime-avibactam (CZA), ceftolozane-tazobactam, imipenem-relebactam, and cefiderocol have expanded therapeutic choices, resistance to these antibiotics is also emerging. Combination therapies therefore remain an important strategy. This study evaluated the in vitro synergistic activity of the CZA-colistin (COL) combination in carbapenem-resistant P. aeruginosa (CRPA) isolates.

Methods: Twelve clinical CRPA isolates obtained from Kocaeli University Hospital (2021-2022) were included. Minimum inhibitory concentration values were determined by broth microdilution, and synergy was assessed using the checkerboard method. Synergy categories were defined as follows fractional inhibitory concentrations index (FICI) ≤ 0.5 synergism, 0.5 < FICI ≤ 1.0 partial synergism, 1.0 < FICI ≤ 4.0 indifference, and >4.0 antagonism.

Results: All isolates were susceptible to colistin, whereas four were resistant to CZA. Checkerboard analysis showed partial synergy in nine of 12 isolates (75.0%), with no antagonism detected. Partial synergy was more frequent in CZA-resistant isolates (100%) than in CZA-susceptible ones (62.5%) and was notably associated with isolates carrying bla_NDM and bla_OXA-48.

Conclusions: CZA-COL combination may offer partial synergy, especially in CZA-resistant CRPA strains; however, broader in vivo and prospective studies are needed to support clinical use.

Klebsiella pneumoniae remains a major cause of invasive infections and is highly capable of acquiring antimicrobial resistance. This exploratory study investigated the antimicrobial resistance profiles and virulence determinants of Klebsiella pneumoniae isolates collected between January and December 2022 at a tertiary-care hospital in Panama City, Panama. A subset of 27 K. pneumoniae isolates was phenotypically and genetically characterized using antimicrobial susceptibility testing. (VITEK^® system), 16S rRNA gene sequencing, multilocus sequence typing (MLST), and virulence gene screening. Our results indicated multidrug resistance (MDR) in 52% (14/27) of these isolates. Virulence gene analysis revealed a high prevalence of genes associated with fimbriae 96% (26/27), capsule formation 96% (26/27), lipopolysaccharide synthesis 59% (15/27), and siderophore production 48% (13/27). The MLST of 14 isolates harboring MDR, resistant, and susceptible phenotypes identified known sequence types (ST348, ST111, ST1104, ST6394, ST806, ST45, and ST163), as well as seven novel sequence types (ST6917-ST6923). Phylogenetic analysis based on 16S rRNA sequences confirmed Klebsiella genus identity and proved close genetic relatedness among isolates. No clear association between MDR profiles and sequence types was observed. These findings suggest the uncontrolled widespread of MDR K. pneumoniae strains containing multiple virulence determinants in a high-complexity health care setting in Panama. We urge the need to strengthen antimicrobial stewardship programs and reinforce infection prevention strategies to limit the spread of high-risk clones and preserve antimicrobial efficacy.