Healthcare-Associated Infections and Antimicrobial Therapy

Topic Information

Dear Colleagues,

Hospital-acquired infections occur frequently among hospitalized patients and are associated with a significant increase in morbidity and mortality. The most common of these include bloodstream infections and respiratory tract and urinary tract infections. Currently, several changes regarding the epidemiology and microbiology of hospital-acquired infections are noted, mostly related to the increasing problem of antimicrobial resistance either in Gram-positives, such as methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus, or in Gram-negatives, such as carbapenem-resistant Enterobacterales, extensively drug-resistant and pan-drug-resistant Acinetobacter baumannii, and multi-drug-resistant Pseudomonas aeruginosa. The problem of increasing antimicrobial resistance leaves few therapeutic options, leading to the revival of old antibiotics or the use of antimicrobial combinations in difficult-to-treat pathogens.

To obtain a better understanding of the problem of hospital-acquired infections and the changes in their antimicrobial treatment, this Topic aims to bring together original studies and literature reviews related to the epidemiology, microbiology, clinical characteristics, treatment, and outcomes of these infections. Furthermore, studies focusing on antimicrobial stewardship and infection control regarding hospital-acquired infections are also welcome.

Dr. Diamantis P. Kofteridis
Dr. Petros Ioannou
Topic Editors

Keywords

Participating Journals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Acta Microbiologica Hellenica amh	-	0.9	1956	24.3 Days	CHF 1200	Submit
Antibiotics antibiotics	5.5	10.2	2012	16.4 Days	CHF 2900	Submit
Epidemiologia epidemiologia	3.2	3.7	2020	25.3 Days	CHF 1400	Submit
Microorganisms microorganisms	4.7	8.2	2013	16.5 Days	CHF 2700	Submit

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Published Papers (6 papers)

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12 pages, 761 KB  

Open AccessArticle

In Vitro Activity of Mecillinam Against ESBL- and Non-ESBL-Producing Escherichia coli and Klebsiella pneumoniae Urinary Isolates

by Alvaro Irigoyen-von-Sierakowski, Ramón Pérez-Tanoira, Pilar Galicia, Manuel Linares-Rufo, María Ropero-Martínez, Harold Bermúdez-Marval, Carlos García-Bertolín, José Vázquez-Mariño and Juan Cuadros-González

Acta Microbiol. Hell. 2026, 71(3), 33; https://doi.org/10.3390/amh71030033 - 26 Aug 2026

Viewed by 295

Abstract

The rising prevalence of multidrug-resistant (MDR) Enterobacterales poses a major challenge for the empirical treatment of urinary tract infections (UTIs). We evaluated the in vitro activity of mecillinam against urinary Escherichia coli and Klebsiella pneumoniae isolates, including extended-spectrum β-lactamase (ESBL)-producing and non-ESBL-producing isolates. [...] Read more.

The rising prevalence of multidrug-resistant (MDR) Enterobacterales poses a major challenge for the empirical treatment of urinary tract infections (UTIs). We evaluated the in vitro activity of mecillinam against urinary Escherichia coli and Klebsiella pneumoniae isolates, including extended-spectrum β-lactamase (ESBL)-producing and non-ESBL-producing isolates. In this prospective, single-center study conducted in Spain (December 2020–March 2021), urinary isolates of E. coli and K. pneumoniae from patients with suspected UTIs were tested for susceptibility to mecillinam and other commonly used antibiotics. A total of 503 isolates were analyzed, including 285 non-ESBL-producing and 218 ESBL-producing isolates. Overall susceptibility was 96.2% (95% CI, 94.2–97.7%) for mecillinam and 98.2% for ertapenem. Mecillinam susceptibility was 96.5% (95% CI, 93.6–98.3%) among non-ESBL-producing isolates and 95.9% (95% CI, 92.3–98.1%) among ESBL-producing isolates, with MIC₅₀ values of 0.5 mg/L and 1 mg/L, respectively. Among ESBL-producing isolates, susceptibility to fosfomycin and trimethoprim–sulfamethoxazole was 72.9% and 44.0%, respectively. These findings demonstrate high in vitro activity of mecillinam against urinary E. coli and K. pneumoniae isolates, including both ESBL-producing and non-ESBL-producing isolates, and provide microbiological evidence supporting further clinical evaluation of pivmecillinam as an oral treatment option for UTIs. Full article

(This article belongs to the Topic Healthcare-Associated Infections and Antimicrobial Therapy)

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15 pages, 1455 KB  

Open AccessArticle

Observed and Forecasted Antibiotic Consumption by ATC/DDD Metrics: A Real-World Modeling Study with Implications for Antimicrobial Stewardship

by Plamen Bekyarov, Momchil Lambev and Silviya Mihaylova

Antibiotics 2026, 15(8), 805; https://doi.org/10.3390/antibiotics15080805 - 18 Aug 2026

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Abstract

Background/Objectives: Monitoring antibiotic consumption is a central component of antimicrobial stewardship because it provides a standardized way to identify changing prescribing patterns, detect potentially excessive use, and support targeted interventions. The WHO ATC/DDD framework is widely used for hospital-based utilization studies and enables [...] Read more.

Background/Objectives: Monitoring antibiotic consumption is a central component of antimicrobial stewardship because it provides a standardized way to identify changing prescribing patterns, detect potentially excessive use, and support targeted interventions. The WHO ATC/DDD framework is widely used for hospital-based utilization studies and enables comparison across wards and time periods. Methods: This single-center observational study used antibiotic data obtained from the hospital pharmacy to compare predicted and observed consumption for 2024 and 2025. Antibiotic use was expressed as DDD per 100 bed-days and analyzed for penicillins, cephalosporins, fluoroquinolones, tetracyclines, nitroimidazole derivatives, lincosamides, and aminoglycosides. The aim of this study was to quantify antibiotic consumption using ATC/DDD methodology, evaluate how closely modeled predictions matched observed values in 2024 and 2025, and identify the antibiotic classes and wards most relevant for stewardship action. Results: Cephalosporins showed the closest agreement between forecasted and observed consumption, with absolute percentage errors of 2.16% in 2024 and 4.61% in 2025 and a two-year mean absolute percentage error of 3.39%. Consumption of fluoroquinolones exceeded predictions, particularly in gynecology, while use of nitroimidazole derivatives was lower than expected, especially in 2025. Use of tetracyclines was absent in both years, and aminoglycosides and lincosamides contributed only minimally to total consumption. Ward-level analysis showed that intensive care accounted for the highest cephalosporin exposure, whereas the largest deviations from forecast were observed in gynecology and high-risk pregnancy wards. Conclusions: Predictive modeling captured antibiotic use reasonably well for some antibiotic classes but showed lower accuracy for others. Forecast accuracy varied across antibiotic groups, indicating that the model performed differently depending on the observed consumption pattern. However, the underlying reasons for these differences cannot be determined from the present aggregated consumption analysis. Full article

(This article belongs to the Topic Healthcare-Associated Infections and Antimicrobial Therapy)

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22 pages, 1647 KB  

Open AccessArticle

Clinical Severity and Organ Dysfunction as Drivers of Mortality in Antimicrobial-Resistant Acinetobacter baumannii Pneumonia: A Retrospective Cohort Study

by Ioana Adelina Stoian, Bianca Balas Maftei, Constantin Aleodor Costin, Radu Crișan-Dabija, Costin Damian, Robert Paval and Carmen Manciuc

Antibiotics 2026, 15(6), 578; https://doi.org/10.3390/antibiotics15060578 - 7 Jun 2026

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Abstract

Background/Objectives: Acinetobacter baumannii is a major cause of hospital-acquired and ventilator-associated pneumonia and is associated with high mortality among critically ill patients. Although antimicrobial resistance remains a major therapeutic challenge, the relative contribution of clinical severity, organ dysfunction, and laboratory parameters to [...] Read more.

Background/Objectives: Acinetobacter baumannii is a major cause of hospital-acquired and ventilator-associated pneumonia and is associated with high mortality among critically ill patients. Although antimicrobial resistance remains a major therapeutic challenge, the relative contribution of clinical severity, organ dysfunction, and laboratory parameters to patient outcomes requires further clarification. Methods: We conducted a retrospective single-center cohort study including 165 patients with microbiologically confirmed A. baumannii pneumonia admitted to the Clinical Hospital of Pneumology Iași, Romania, between 2019 and 2025. Clinical, laboratory, and outcome data were analyzed, and multivariable logistic regression was performed to identify independent predictors of in-hospital mortality. Results: In-hospital mortality was independently associated with older age (OR: 1.05 per year, 95% CI: 1.01–1.08, p = 0.005), sepsis (OR: 5.23, 95% CI: 1.93–16.5, p = 0.002), and mechanical ventilation (OR: 6.71, 95% CI: 3.02–15.6, p < 0.001). In exploratory analyses restricted to patients with available lactate measurements, lactate levels were not significantly associated with mortality, whereas acute kidney injury and dynamic renal deterioration were associated with increased mortality. Inflammatory markers, particularly neutrophil-to-lymphocyte ratio and C-reactive protein at 72 h, were significantly higher in non-survivors. Conclusions: These findings suggest that mortality in A. baumannii pneumonia is more closely associated with clinical severity, sepsis, respiratory failure, and evolving organ dysfunction than with isolated laboratory parameters. Early recognition of sepsis, acute kidney injury, and respiratory failure, together with serial assessment of inflammatory biomarkers, may support improved risk stratification in this high-risk population. Full article

(This article belongs to the Topic Healthcare-Associated Infections and Antimicrobial Therapy)

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15 pages, 266 KB  

Open AccessArticle

Beyond the Needle: Knowledge of Blood-Borne Infection Transmission and Prevention Among Dental Students—A Cross-Sectional Study

by Catalina-Iulia Saveanu, Diana Dumitriu, Bogdan Ioan Condrea, Alexandra Ecaterina Saveanu, Daniela Anistoroaei, Vasilica Toma and Ana-Maria Fatu

Epidemiologia 2026, 7(3), 67; https://doi.org/10.3390/epidemiologia7030067 - 12 May 2026

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Abstract

Background/Objectives: Aim: Dental practice involves continuous exposure to saliva and blood, creating persistent opportunities for cross-infection if contaminated instruments are not processed correctly. This study aimed to evaluate dental students’ knowledge regarding blood-borne infections and infection prevention measures, and to compare knowledge levels [...] Read more.

Background/Objectives: Aim: Dental practice involves continuous exposure to saliva and blood, creating persistent opportunities for cross-infection if contaminated instruments are not processed correctly. This study aimed to evaluate dental students’ knowledge regarding blood-borne infections and infection prevention measures, and to compare knowledge levels according to academic year and sex. Materials and Methods: A structured questionnaire consisting of 21 single-best-answer questions was administered to 93 undergraduate dental students (Years I–VI) from the Faculty of Dental Medicine, “Gr. T. Popa” University of Medicine and Pharmacy, Iași, Romania. The questionnaire evaluated knowledge related to instrument classification, cleaning and disinfection procedures, sterilization parameters, autoclave monitoring tests, and storage conditions. Demographic data were also collected. Statistical analysis was performed using IBM SPSS Statistics version 31, and associations between responses and demographic variables were assessed using chi-square tests. Associations between responses and demographic variables (academic year and sex) were evaluated using chi-square tests (p < 0.05). Results: Most participants correctly identified several key steps in the instrument processing circuit, including the use of high-level disinfectant–detergent solutions (88.2%) and the need for disinfection followed by sterilization (76.3%). However, important knowledge gaps were identified regarding autoclave pre-use checks, correct sterilization temperatures and exposure times, recommended sterile storage periods, and the interpretation of sterilization monitoring tools such as type 5 chemical integrators, Bowie–Dick tests, and Helix tests. Knowledge levels differed significantly according to academic year (p < 0.05). Conclusions: Although overall awareness of instrument processing procedures among dental students was generally satisfactory, several inconsistencies were observed in critical technical aspects of sterilization and monitoring. These findings highlight the need for strengthened infection control education and repeated practical training to reduce the risk of cross-infection in dental practice. Full article

(This article belongs to the Topic Healthcare-Associated Infections and Antimicrobial Therapy)

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16 pages, 1689 KB  

Open AccessArticle

Phenotypic and Metabolic Variations in High-Risk Clones of Multidrug-Resistant Pseudomonas aeruginosa

by Sonia J. Gutierrez, Juan David Escobar Prieto, Deninson Alejandro Vargas, Richard Burchmore, Karl Burguess and Adriana Correa

Microorganisms 2026, 14(3), 699; https://doi.org/10.3390/microorganisms14030699 - 20 Mar 2026

Viewed by 816

Abstract

The global spread of high-risk clo1nes (HRCs) of multidrug-resistant (MDR) Pseudomonas aeruginosa has hindered infection control and treatment strategies worldwide. In Colombia, globally relevant HRCs such as ST235 and ST111 have been widely reported. In this study, we evaluated phenotypic and metabolic variations [...] Read more.

The global spread of high-risk clo1nes (HRCs) of multidrug-resistant (MDR) Pseudomonas aeruginosa has hindered infection control and treatment strategies worldwide. In Colombia, globally relevant HRCs such as ST235 and ST111 have been widely reported. In this study, we evaluated phenotypic and metabolic variations associated with intracellular survival and dissemination in P. aeruginosa. A total of 100 clinical isolates were collected from 22 hospitals in Colombia. The isolates had been previously characterized and classified as MDR or susceptible strains (SSs), and their sequence types (STs) had been earlier determined. Based on this prior characterization, isolates were grouped in this study as multidrug-resistant high-risk clones (HRC, n = 50; corresponding to sequence types ST235 and ST111), multidrug-resistant non-high-risk clones (NHRCs, n = 27; non-ST235/ST111), and susceptible strains (SS, n = 23; also, non-ST235/ST111). Phenotypic traits, including motility, spontaneous mutation frequency, biofilm formation, and pigment production, were evaluated. In addition, a subset of 30 isolates was assessed for intracellular survival in vitro and metabolomic profiling using liquid chromatography-mass spectrometry. HRC isolates exhibited significantly reduced motility compared with NHRC and SS isolates (swarming: HRC vs. NHRC, p = 0.0032; HRC vs. SS, p = 0.010; swimming: HRC vs. NHRC and SS, p < 0.0001; twitching: HRC vs. SS, p = 0.0004), as well as lower pigment production (pyocyanin: HRC vs. NHRC and SS, p < 0.0001; pyoverdine: HRC vs. NHRC, p < 0.0001). Metabolomic analysis revealed increased concentrations of metabolites associated with iron acquisition and siderophore-related pathways in HRC isolates. Overall, these findings suggest that P. aeruginosa HRCs display distinct phenotypic and metabolic patterns that may contribute to persistence and dissemination in clinical settings, contributing to their epidemiological success. Full article

(This article belongs to the Topic Healthcare-Associated Infections and Antimicrobial Therapy)

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19 pages, 404 KB  

Open AccessArticle

Risk Stratification and Mortality in Clostridioides difficile Infection: Clinical Determinants and Prognostic Assessment

by Luís Furtado

Acta Microbiol. Hell. 2026, 71(1), 7; https://doi.org/10.3390/amh71010007 - 10 Mar 2026

Viewed by 1676

Abstract

Clostridioides difficile infection (CDI) remains a major cause of healthcare-associated morbidity and mortality, particularly among older adults and patients with recent healthcare exposure, underscoring the need for early risk stratification and accurate prognostic assessment. This retrospective observational study evaluated clinical, laboratory, and therapeutic [...] Read more.

Clostridioides difficile infection (CDI) remains a major cause of healthcare-associated morbidity and mortality, particularly among older adults and patients with recent healthcare exposure, underscoring the need for early risk stratification and accurate prognostic assessment. This retrospective observational study evaluated clinical, laboratory, and therapeutic factors associated with disease severity and in-hospital mortality, and assessed the predictive performance of the ATLAS score and the Charlson comorbidity index. A total of 101 adult inpatients with laboratory-confirmed CDI admitted to a Portuguese tertiary care hospital were included. Data were extracted from clinical records and analysed using comparative statistics, multivariable logistic regression, and Kaplan–Meier survival analysis. Advanced age, elevated white blood cell count, renal dysfunction, and prior exposure to multiple antibiotic classes were independently associated with increased disease severity and mortality. The ATLAS score demonstrated good discriminative ability, particularly for short-term mortality, and showed higher sensitivity compared with the Charlson comorbidity index. These findings provide additional evidence on clinical and laboratory factors associated with severe CDI and in-hospital mortality, while supporting the utility of the ATLAS score as a practical tool for early risk stratification in hospitalised patients. Full article

(This article belongs to the Topic Healthcare-Associated Infections and Antimicrobial Therapy)

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