Journal of Hospital Infection最新文献

Background: Interpretation of microbial tolerance and resistance to disinfectants has long been inconsistent, with heterogeneous definitions and no clinically meaningful threshold. We propose the concept of replication capacity after use (RCAU) as a practical endpoint to assess whether microbial survival after disinfectant exposure constitutes a clinically relevant phenomenon under recommended use conditions. RCAU is defined as the ability of micro-organisms to replicate after exposure at recommended application concentration and exposure time. A critical RCAU corresponds to failure of a standardized quantitative suspension test.

Methods: We reassessed published evidence across the most common disinfectant substances listed by the German Association for Applied Hygiene. Reported findings on survival, tolerance and resistance were re-evaluated against the RCAU definition, with particular attention to whether testing was performed using quantitative suspension methods at application concentration.

Results: No disinfectant group has demonstrated a critical RCAU under application conditions in standardized suspension testing. Reports of reduced susceptibility or microbial survival exist, but many were not based on suspension tests at use concentrations, making interpretation with respect to RCAU uncertain. Transient or reversible adaptations have been described, yet without evidence of a critical RCAU. Only triclosan and silver compounds show established resistance mechanisms, though even here no critical RCAU has been confirmed under standardized testing.

Conclusion: RCAU provides a transparent, use-condition-anchored framework to differentiate non-critical survival from clinically relevant resistance development. Applied across disinfectant classes, it shows that no critical failures have occurred at use concentrations, although many reported findings were not assessed by standardized suspension tests.

Background: Surgical site infections (SSIs) are a significant cause of morbidity and mortality among healthcare-associated infections, as well as increased economic and environmental costs.

Aim: This study aimed to determine the environmental impacts of SSIs and the resulting carbon footprint.

Methods: This descriptive study was conducted with the participation of 553 patients who underwent surgery at a university and a city hospital in Central Anatolia between March and June 2025. Data were collected using a sociodemographic information form, the Surgical Wound Assessment Form based on the criteria of the European Center for Disease Prevention and Control and the Carbon Footprint Calculation Tool based on the calculation tool of the Sustainable Healthcare Coalition.

Findings: A total of 91 individuals (16.5%) experienced SSIs. The total carbon footprint during the follow-up and treatment period of 91 patients with SSI was calculated as approximately 1735 kg CO₂ equivalent (CO₂e). The largest source of emissions was hospitalizations (clinic and intensive care stays: 1133 kg CO₂e), which accounted for over 70% of the total. This was followed by patient transport (142.4 kg CO₂e) and magnetic resonance imaging (108.0 kg CO₂e). It was determined that the development of SSIs imposes a carbon burden of 16.8 kg CO₂e per patient on average compared with a standard surgical procedure.

Conclusions: This study has quantitatively demonstrated that SSIs have a measurable and significant environmental burden in addition to their known clinical and economic burden. Preventing SSIs is a critical strategy for ensuring both patient safety and economic and ecological sustainability in surgery.

Unexpected positive cultures (UPCs) during revision of orthopaedic implants in presumed aseptic revision surgeries represent a significant clinical challenge; indeed, it is very difficult to state whether a positive culture indicates a true infection or merely sample contamination. In hip, knee, shoulder, elbow and spinal procedures, the incidence of UPCs remains clinically relevant, ranging from approximately 7% in elbow revisions to approximately 28% in spinal revisions. The organisms most commonly isolated - coagulase-negative staphylococci (23-52%) and Cutibacterium acnes (24-65%) - are classic low-virulence pathogens with high contamination potential, reinforcing the uncertainty that accompanies their detection. Although published outcomes vary, most studies suggest that a single UPC rarely compromises implant survivorship, supporting the interpretation that many isolated findings represent contamination rather than infection. In contrast, multiple cultures positive for the same organism indicate occult infection more strongly, as highlighted by the International Consensus Meeting 2023 guidelines, which associate concordant multi-culture positivity with a higher risk of re-revision or failure. Consequently, the emerging clinical consensus is that single low-virulence UPCs can often be observed, whereas multiple concordant UPCs warrant management as true infection, guiding decisions regarding antimicrobial therapy and postoperative surveillance. Given the persistent variability in published management strategies, further study is needed to standardize responses to UPCs. Finally, rapid, cost-effective intra-operative diagnostics may ultimately improve real-time detection of infection, and reduce uncertainty in revision of orthopaedic implants.

Background: Hospital wastewater (HWW) serves as a critical reservoir for antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs), especially those conferring resistance to quinolones, fluoroquinolones and macrolides. This study investigated the prevalence and seasonal dynamics of ARB and ARGs in HWW from the Kathmandu Valley, Nepal.

Methods: We collected and analysed 16 untreated HWW samples from eight hospitals during the summer and winter seasons (2022-2023). Physicochemical parameters, prevalence of ARB, selected ARGs (qnrS, aac(6')-Ib-cr, erm(B)) and class 1 integron (intI1) were assessed. Results were compared by hospital type and season.

Results: Significant seasonal differences were observed in temperature (P = 0.00024) and total suspended solids (P = 0.042). Klebsiella pneumoniae (31.67%) and Escherichia coli (28.33%) were the most frequently isolated ARB. K. pneumoniae exhibited very high resistance to ciprofloxacin (97.74%) and levofloxacin (89.47%). Among the targeted genes, the aac(6')-Ib-cr gene was the most prevalent (55.67%), followed by intI1 (50%), qnrS (25%) and erm(B) (11.67%). The erm(B) gene was significantly more prevalent in medium-sized hospitals (P = 0.001). No significant seasonal variation was observed for ARGs or the mobile genetic elements (P > 0.05). Although not statistically significant, strong correlations were observed between qnrS prevalence and pH (ρ = 0.912) and ammonia (ρ = 0.812), suggesting potential environmental influences on the dissemination of resistance.

Conclusion: The HWW is a significant antimicrobial resistance reservoir, emphasizing improved wastewater treatment and antibiotic stewardship to mitigate resistance dissemination.

Background: Healthcare-associated infections are a major concern in intensive care units (ICUs), where early detection of transmission cluster is critical. Whole-genome sequencing remains the reference method for outbreak investigation but is limited by cost and turnaround time. The IR Biotyper (IRBT) provides rapid phenotypic clustering, but its core-genome-level performance remains insufficiently evaluated.

Aim: This study evaluated the analytical performance of IRBT at the core-genome level for detecting clinically relevant Gram-negative bacterial cross-transmission in ICUs.

Methods: In this prospective single-centre study, all clinical, screening and environmental isolates of Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Enterobacter cloacae complex and Stenotrophomonas maltophilia that were recovered in a 36-bed ICU over seven months were analysed. Transmission clusters were assessed using core-genome multi-locus sequence typing (cgMLST). IRBT spectral distances were compared with allelic distances from cgMLST. Diagnostic performance metrics were calculated using both manufacturer-recommended (Bruker) and automated IRBT thresholds.

Findings: Among 283 isolates from 135 patients, cgMLST identified 23 transmission cluster events. Using Bruker thresholds, IRBT achieved high species-specific specificity (ranging from 0.91 to 0.99) and negative predictive values (NPVs: ≥0.94) across all species. E. cloacae complex showed near-perfect performance (sensitivity: 0.94, specificity: 0.99 and NPV: 0.998), while K. pneumoniae and E. coli demonstrated strong concordance (sensitivity ≥0.81). Lower sensitivity was observed for P. aeruginosa (0.77) and S. maltophilia (0.70). Automated thresholds improved specificity and positive predictive value but reduced sensitivity. Receiver operating characteristic curves confirmed high discriminatory power (area under the curve value: 0.899-0.999).

Conclusions: IRBT provides rapid, species-specific phenotypic clustering for ICU Gram-negative bacterial transmission cluster surveillance.

Background: Piperacillin-tazobactam (TZP) is widely used empirically in Danish hospitals despite guideline restrictions, making it an important target for antimicrobial stewardship (AMS).

Aim: The aim of this study was to evaluate the impact of a multi-disciplinary AMS programme on TZP use, prescribing quality and clinical safety outcomes at a Danish university hospital.

Methods: A prospective, quasi-experimental study using interrupted time series (ITS) and two hospital-wide point prevalence surveys (PPS; 2021 and 2023) was conducted from January 2022 to December 2024. The AMS programme, introduced in January 2023, included prospective audit and feedback, education and monthly department-level reports. Days of therapy (DOT)/1,000 bed-days assessed antimicrobial trends. Logistic regression analysed guideline adherence and prescribing quality indicators; Poisson regression assessed changes in proportional DOT.

Results: Among 156,035 admissions, 92,346 (59.2%) occurred in AMS-implementing departments. TZP use decreased by 19.5% (95% confidence interval [CI]: -25.5 to -13.5%; P < 0.001) but increased by 26.7% in non-AMS departments (95% CI: 18.6-34.9%; P < 0.001). Benzylpenicillin, ampicillin and aminoglycoside use increased by 14.2%, 20.2% and 36.4%, respectively, in AMS wards. PPS findings (N = 262) showed improved guideline adherence (odds ratio [OR]: 2.32, 95% CI: 1.38-3.90), documentation of indication (OR: 3.06), treatment planning (OR: 9.83) and reassessment within 72 h (OR: 2.52). Thirty-day readmission decreased from 11.6% to 10.2% (P = 0.0001), while in-hospital mortality remained unchanged (6.0% vs 6.1%; P = 0.962).

Conclusion: A multi-disciplinary AMS programme was associated with reduced TZP use and improved prescribing quality in participating departments without adverse effects on safety indicators. These findings support AMS as an effective strategy to optimise antibiotic use.

Background: Wet environmental niches in hospitals may act as reservoirs for carbapenem-resistant Pseudomonas species, posing a risk for horizontal transfer and spread of carbapenemase genes.

Aim: To determine the presence of carbapenem-resistant non-aeruginosa Pseudomonas spp. in the wet hospital environment in a non-outbreak setting and to characterize the genetic context and spread of carbapenemase genes.

Methods: A two-round point-prevalence study was conducted in sink and shower drains of the Erasmus MC (Rotterdam, The Netherlands) in 2022 and 2023. Carbapenem-resistant non-aeruginosa Pseudomonas isolates were screened for carbapenemase activity and genes, followed by sequencing of carbapenemase gene-positive isolates.

Findings: A total of 747 drains were screened, with 98.8% (N = 738) sampled twice. Carbapenem-resistant strains were detected in 27 out of 744 (3.6%) and 48 out of 741 drains (6.5%) during sampling rounds 1 and 2, respectively, with significantly more contaminated shower than sink drains in round 2 (P = 0.017). Eight isolates contained a carbapenemase gene, involving bla_IMP (N = 3) and bla_VIM (N = 5), all detected during round 2. An identical bla_IMP-15-encoding plasmid was found in one Pseudomonas arcuscaelestis and two Pseudomonas monteilii, isolated from shower drains in three wards. Five isolates of a novel Pseudomonas species shared an identical bla_VIM-2-containing integron, located on the chromosome.

Conclusion: Carbapenem-resistant non-aeruginosa Pseudomonas spp. were present in ∼5% of drains. Evidence of horizontal transfer of a bla_IMP-15-encoding plasmid and its spread between wards was found, indicating that these isolates generate a reservoir in drains from which carbapenemase genes can spread through hospital plumbing and reappear in other patient rooms.

Background: There are limited resources to detect and interpret cluster signals in resource-limited hospitals. The aim was to improve the interpretation of pathogen spatiotemporal clustering detected using the SaTScan algorithm - a method that uses space-time scan statistics to detect cluster signals that occur more often than expected.

Methods: Analysis of electronic data of inpatients with clinical specimens culture positive for seven antimicrobial-resistant pathogens in two tertiary hospitals in Thailand from January to December 2022 was performed. Space-time uniform scan statistics were applied in SaTScan. Four analyses were performed. Analysis 1 did not include antimicrobial susceptibility test (AST) result profiles. Analyses 2, 3, and 4 included AST results of antibiotics that had ≥70%, ≥80%, and ≥90% of available results among the included patients, respectively.

Findings: There were 125,848 microbiology data records collected from a 1188-bed hospital and 54,069 records from a 773-bed hospital in 2022. Multiple cluster signals were detected in both hospitals, including clusters of carbapenem-resistant Gram-negative organisms across different wards over different time periods. The number of cluster signals detected decreased with increasing thresholds used to select antibiotics to be included in the analysis. For instance, Analysis 2 detected 33 clusters, which reduced to 4 clusters in Analysis 4 in the 1188-bed hospital data. Similar patterns were also observed in the 773-bed hospital data. The temporal occurrence of detected cluster signals coincided with the period during which AST results were unavailable in Analyses 2 and 3.

Conclusion: The findings suggest that SaTScan is applicable to detect potential cluster signals in resource-limited settings, and the interpretation of detected signals could be supported by graphical presentations of temporal changes in the availability of AST data.