Search Results (1,776)

Background: Healthcare-associated infections (HAIs) and antimicrobial resistance are major global public health challenges, influenced by patient clinical complexity and prescribing practices. Methods: Three-point prevalence surveys (PPSs) were conducted (P1: November 2024; P2: June 2025; P3: November 2025), involving 456 patients at the University Hospital “San Giovanni di Dio e Ruggi d’Aragona”, Salerno, Italy. Results: The prevalence of HAIs fluctuated between 3.1% (P1) and a peak of 6.1% (P2), before decreasing to 1.9% (P3), correlating with the presence of multidrug-resistant pathogens in critical care areas. The prevalence of antibiotic use remained stable (~48%), with a decrease in carbapenem use (from 12% to 9%). A decline in ‘unknown’ McCabe scores from 24.6% to 6.8% (p < 0.001) was also observed, suggesting an improvement in completeness of prognostic data, although changes in data collection practices may also have contributed to this change. Conclusions: We showed an association between clinical severity, prolonged hospitalization, invasive device use, and infection risk in a single tertiary-care hospital, within an exploratory, cross-sectional framework. Despite high healthcare pressure, improvements were observed in antimicrobial stewardship and clinical surveillance. Future strategies should focus on optimal device management and on extending surveillance activities to medical wards with increasing patient complexity. Full article

Empirical management of acute pyelonephritis in Eastern Europe is increasingly constrained by extended-spectrum β-lactamase (ESBL)-producing Enterobacterales and by uropathogen phenotypes—such as strong biofilm formation—which may further blunt antimicrobial activity. We aimed to characterise resistance mechanisms, minimum inhibitory concentration (MIC) distributions, biofilm-forming capacity, and the in vitro performance of carbapenem-sparing agents and to test whether these microbiological features improve prediction of clinical failure beyond standard bedside risk scores. We retrospectively analysed 102 Enterobacterales isolates recovered from 129 consecutive culture-confirmed adult pyelonephritis admissions at “Victor Babeș” University Hospital, Timișoara (March 2022–March 2025). MIC values were determined by Vitek 2 and interpreted using EUCAST v13 breakpoints; ESBL, AmpC, and carbapenemase phenotypes were confirmed by combination disk and modified carbapenem inactivation methods. Biofilm formation was quantified by the microtiter-plate crystal-violet assay. Mediation, Restricted Mean Survival Time (RMST), and decision-curve analyses were used to assess added clinical value. ESBL was confirmed in 30/102 (29.4%) isolates, AmpC in 9 (8.8%), and carbapenemase in 4 (3.9%). ESBL+ isolates were more often strong biofilm formers (33.3% vs. 12.5%; p = 0.014) and showed a 4- to 16-fold rightward MIC shift for cefepime, piperacillin–tazobactam, and ciprofloxacin. Among carbapenem-sparing agents, ceftazidime–avibactam (96.7% S), fosfomycin (80.0% S), and amikacin (73.3% S) retained the highest activity against ESBL+ isolates. Strong biofilm formation and the ESBL phenotype were independently associated with worse outcomes (adjusted OR 3.5 and 4.7); an exploratory mediation analysis suggested that biofilm formation may explain part of the observed association between the ESBL phenotype and treatment failure and that delayed effective therapy may account for a further portion of this association. A microbiology-enhanced model that added the ESBL phenotype, biofilm strength, and acquisition setting to routine clinical variables improved discrimination over a clinical-only baseline (AUC 0.89 vs. 0.71) and showed a higher net benefit on exploratory decision-curve analysis across the 10–40% threshold range. These predictive findings derive from a single-centre cohort with a small number of events and were only internally validated; they require validation in independent cohorts before any clinical application can be considered. The ESBL phenotype and strong biofilm formation were each independently associated with worse outcomes in pyelonephritis and may help identify candidate isolates for carbapenem-sparing strategies anchored on ceftazidime–avibactam, fosfomycin, and amikacin; given the observational, single-centre design, these associations should be regarded as hypothesis-generating. Full article

Background/Objectives: Aztreonam/avibactam is a promising treatment option for serious infections caused by metallo-β-lactamase-producing carbapenem-resistant Enterobacterales (MBL-CRE). However, the labeled regimen is operationally demanding because it requires frequent, prolonged infusions, and the recommended loading dose does not match the commercially available vial strength. This population pharmacokinetic (PopPK)-based Monte Carlo simulation study aimed to optimize aztreonam/avibactam dosing across renal function strata while maintaining pharmacokinetic/pharmacodynamic (PK/PD) target attainment. Methods: Published PopPK models for aztreonam and avibactam were reconstructed and applied in Monte Carlo simulations. Virtual adult patients (body weight 70 kg) were stratified into five renal function groups according to creatinine clearance (CrCL): 101–120, 81–100, 51–80, 31–50, and 15–30 mL/min. Simulated scenarios varied infusion duration, dosing interval, maintenance dose, and loading strategy. Prespecified PK/PD targets were 60% fT > MIC (the percentage of dosing interval that free drug concentration remains above the minimum inhibitory concentration) for aztreonam (MIC 8 mg/L) and 50% fT > CT (the percentage of dosing interval that free drug concentration remains above the critical threshold concentration) for avibactam (CT 2.5 mg/L). A joint probability of target attainment (PTA) ≥ 90% was considered acceptable. Results: Regimen performance differed across renal function strata. For patients with CrCL > 80 mL/min, the labeled q6h regimen infused over 3 h remained the most robust option, whereas shortening the infusion to 1 h or 2 h reduced target attainment. In the CrCL 51–80 and 31–50 mL/min subgroups, both q6h/3 h and q6h/2 h regimens generally achieved acceptable PTA. However, in the CrCL 31–50 mL/min subgroup receiving q6h/2 h administration, omitting a loading dose was associated with reduced early avibactam exposure. In the CrCL 15–30 mL/min subgroup, a simplified half-vial regimen (0.75/0.25 g q8h/2 h) provided PTA comparable to that of the complex labeled reduced-dose regimen. Across loading dose scenarios, omission of the loading dose was best supported in the CrCL 51–80 mL/min subgroup, whereas retaining the labeled loading dose remained the more prudent approach in the CrCL 31–50 mL/min subgroup when a 2 h infusion was used. Conclusions: PopPK-guided, renal function-stratified simplification of aztreonam/avibactam dosing may improve clinical practicality without materially compromising PK/PD target attainment in selected patient subgroups. A 2 h infusion appears a reasonable alternative for patients with CrCL 31–80 mL/min, and a 0.75/0.25 g q8h/2 h half-vial regimen may be considered a plausible exploratory option for patients with CrCL 15–30 mL/min. These findings support more feasible administration strategies, but prospective clinical validation remains necessary. Full article

Serratia spp., particularly Serratia marcescens, have emerged as clinically important opportunistic pathogens and are increasingly recognized as causes of healthcare-associated infections, especially among critically ill and immunocompromised patients. Their remarkable ecological adaptability, persistence in hospital environments, and capacity to acquire multiple antimicrobial resistance determinants have contributed to the global emergence of multidrug-resistant strains and complicated therapeutic management. This review aims to comprehensively analyze the epidemiology, virulence mechanisms, antimicrobial resistance patterns, and current and emerging therapeutic strategies associated with Serratia spp. The manuscript is based on a critical review and analysis of previously published literature retrieved from electronic scientific databases focusing on clinically relevant Serratia spp. infections and resistance trends. The reviewed literature demonstrates that Serratia spp. combine intrinsic resistance mechanisms, particularly inducible chromosomal AmpC β-lactamases, with acquired resistance determinants including extended-spectrum β-lactamases, carbapenemases, aminoglycoside-modifying enzymes, and plasmid-mediated quinolone resistance. Horizontal gene transfer and biofilm formation further enhance bacterial persistence, dissemination, and adaptation within healthcare settings. Clinically, these pathogens are associated with device-related infections, bloodstream infections, pneumonia, urinary tract infections, and hospital outbreaks, where increasing multidrug and carbapenem resistance significantly limits therapeutic options. Novel β-lactam/β-lactamase inhibitor combinations and cefiderocol represent promising therapeutic approaches, although treatment success remains highly dependent on accurate identification of underlying resistance mechanisms. This review highlights the growing public health importance of Serratia spp. and underscores the need for improved surveillance, molecular diagnostics, antimicrobial stewardship, and the development of innovative therapeutic strategies in the context of the evolving antimicrobial resistance crisis. Full article

Background: Staphylococcus aureus neonatal osteomyelitis (SA-NOm) is a rare condition with the potential for lifelong skeletal morbidity. Available evidence remains scarce and inconsistent, with notable differences in clinical presentation, therapeutic regimens, and reported outcomes, underscoring the need for a systematic evaluation combining clinical experience with existing literature. Methods: We retrospectively reviewed data from all neonates admitted to Regina Margherita Children’s Hospital, Turin, Italy, between 2017 and 2024 with a diagnosis of SA-NOm. A structured narrative review of the pertinent literature published over the past 25 years was conducted to identify additional cases and compare management approaches. Results: Four neonates with SA-NOm were identified at our center (institutional cohort) while a literature review retrieved 38 additional cases (literature cohort) to establish a combined cohort (n = 42). Of these, 78% were born at term, with a male-to-female ratio of 1.6:1 (26 males, 16 females). Approximately half of the combined cohort presented identifiable risk factors for SA-NOm, including neonatal intensive care unit admission, prematurity, sepsis, or maternal complications. Across the combined cohort, the mean age at presentation was 19 days. The most common presenting signs were local swelling and reduced mobility of the affected limb, although systemic symptoms often complicated early recognition. Long bones were most frequently involved—particularly the femur, humerus, and tibia—with equal distribution between upper and lower extremities. The mean intravenous antibiotic duration for the combined cohort was 31.6 days, followed by two to three weeks of oral therapy. Empiric regimens varied, including glycopeptides alone or combined with second- or third-generation cephalosporins, anti-staphylococcal penicillins, or carbapenems. Sequelae rates were rarely reported in the literature, likely due to limited follow-up, whereas extended surveillance in our cohort revealed substantial long-term morbidity, including restricted joint mobility, limb length discrepancy, and persistent radiographic abnormalities. Conclusions: SA-NOm, due to its rarity and potential for long-term skeletal sequelae, requires early diagnosis and timely empiric antibiotic therapy based on local resistance data. Prospective multicenter studies are needed to define standardized diagnostic and therapeutic protocols. Full article

Multidrug-resistant organisms, particularly carbapenem-resistant Enterobacterales (CRE), represent a major global health threat. In settings with endemic circulation of carbapenem-resistant organisms, early identification of colonised patients before hospital admission may play a critical role in limiting in-hospital spread and guiding infection prevention strategies. We conducted a retrospective monocentric observational study including all patients evaluated for hospital admission in 2025. Patients presenting predefined epidemiological or clinical risk factors underwent risk-based pre-admission screening for CRE. Patient-level deduplication was applied to microbiologically positive records. Among 2694 patients evaluated for hospital admission, 1084 met predefined screening criteria and underwent rectal swab testing. Overall, 191 unique patients were confirmed as carriers of carbapenemase-producing Enterobacterales, corresponding to 17.6% of screened patients and 7.1% of the overall cohort evaluated for admission. KPC was the most prevalent carbapenemase gene (102/191, 53.4%), followed by NDM (57/191, 29.8%) and KPC/NDM co-production (14/191, 7.3%). Less frequent gene profiles included VIM, OXA-48, and combined carbapenemase patterns. In high-endemic healthcare settings, risk-based pre-admission screening may represent a pragmatic component of infection prevention pathways by supporting early identification of patients with probable CRE/CPE carriage. When analysed at the patient level, such programmes can provide useful operational and epidemiological information for admission management and infection control planning. Full article

Introduction: Plazomicin, a novel, semi-synthetic aminoglycoside designed to overcome most aminoglycoside-modifying enzymes (AMEs), represents a therapeutic alternative to traditional aminoglycosides for complicated urinary-tract infections (cUTIs). In this review, we sought to evaluate the available data on drug resistance. Methods: We performed a thorough search across four databases (PubMed, Embase, Scopus, and Web of Science) from their inception to 4 November 2025 to identify relevant studies. The published Clinical and Laboratory Standards Institute (CLSI) antimicrobial susceptibility breakpoints for Enterobacterales were applied. Results: Fifty-five studies, out of a total of 905 records originally identified, were eligible for data extraction and analysis, yielding antimicrobial susceptibility data for 80,159 clinical isolates. The overall resistance of consecutive Enterobacterales isolates to plazomicin was 0–9.4%, and specifically for Escherichia coli and Klebsiella spp. isolates were up to 4.7% and 15.2%, respectively. Among selected isolates with specific resistance mechanisms, the resistance of carbapenem-resistant Enterobacterales (CRE) was 1.8–67.6%, and specifically for carbapenem-resistant E. coli and Klebsiella spp. isolates, 0–10% and 0.3–90%, respectively. Among multi-drug-resistant (MDR) isolates, up to 24.6% of MDR Klebsiella spp. isolates and up to 15% of MDR E. coli isolates were resistant to plazomicin. Among non-fermenting Gram-negative bacteria, the MIC₉₀ values were consistently high. Conclusions: The demonstrated high activity of plazomicin against consecutive Enterobacterales isolates and the considerable, yet variable, activity against selected resistant isolates suggest its consideration as a valuable option in the treatment of complicated urinary-tract infections. Full article

Background/Objectives: Klebsiella (K.) pneumoniae is a significant pathogen in both humans and animals. However, data on its occurrence in animals in Germany remain limited. This study aimed to investigate the antimicrobial resistance (AMR) phenotypes, AMR genes, and virulence traits of animal-derived K. pneumoniae isolates from Germany. Methods: A total of 59 K. pneumoniae isolates obtained in 2023 from dogs, cats, horses, cattle, and chickens across 11 German federal states were analysed. Phenotypic antimicrobial susceptibility testing (AST) was performed, and whole-genome sequencing (WGS) was used for genomic characterisation, including detection of AMR genes, virulence-associated genes, sequence types (STs), and plasmid replicons. Results: Most isolates (78%) were susceptible to all tested antibiotics, while three isolates were classified as multidrug-resistant (MDR). Resistance was most frequently observed for piperacillin (n = 8) and trimethoprim/sulfamethoxazole (n = 4). Carbapenem resistance was detected in two isolates (one from a dog and one from a cat), and phenotypic colistin resistance in one dog isolate. WGS identified 96 AMR genes across isolates, with 20–42 AMR determinants per isolate, conferring resistance to β-lactams, aminoglycosides, fluoroquinolones, sulfonamides, tetracyclines, trimethoprim, and fosfomycin. Ten extended-spectrum β-lactamase (ESBL)-producing isolates carried genes including bla_CTX-M-15, bla_SHV-2, bla_SHV-27, bla_SHV-42, bla_SHV-106, and bla_TEM-158. Although fosA was detected in all isolates, only three exhibited phenotypic resistance to fosfomycin. A total of 52 STs were identified, including high-risk clones. One hypervirulent isolate (ST60) carrying hypervirulence-associated genes rmpA and iroB was detected. Plasmid replicons were present in 70% of isolates, while plasmid-associated AMR genes were identified in nine isolates. Conclusions: This study demonstrates the genomic diversity of K. pneumoniae identified in companion animals and highlights the presence of AMR and virulence determinants relevant to a One Health context. Full article

Introduction: Urinary tract infections (UTIs) represent a growing concern in both clinical practice and public health, affecting hospitalized and outpatient populations across all ages and genders. This study aims to evaluate the prevalence of uropathogens and their antimicrobial resistance profiles in male and female patients comparatively at a tertiary urological center. Materials and Methods: A retrospective descriptive analysis was conducted, covering three identical 6-month periods—September 1 to February 28—in three consecutive years from 2023 to 2025. The study included 2270 male patients (2270. 57.06%) and 1708 female patients (1708. 42.94%), all with at least one positive urine culture (>10⁵ CFU/mL). Data on age, gender, bacterial species, and antimicrobial agents were collected and analyzed. Results: A higher prevalence of Gram-negative bacteria was observed compared to Gram-positive bacteria in both male (1752; 77.18% vs. 518; 22.82%) and female (1369; 80.15% vs. 339; 19.85%) groups. The most common microorganisms were Escherichia coli, followed by Klebsiella and Enterococcus. Klebsiella showed high rates of antimicrobial resistance, especially in males, across various antibiotic classes such as amoxicillin-clavulanic acid (60.6% vs. 43.25%), levofloxacin (40.18% vs. 27.91%), aztreonam (37.4% vs. 27.27%), and ceftazidime (36.23% vs. 24.03%). High resistance levels, although not statistically significant, were also noted for trimethoprim/sulfamethoxazole (43.64%) and nitrofurantoin (65.69%). In males, E. coli exhibited higher resistance rates to trimethoprim/sulfamethoxazole (44.65% vs. 32.89%), levofloxacin (43.27% vs. 30.78%), and amoxicillin-clavulanic acid (40.18% vs. 27.19%). Carbapenems remained highly susceptible in both groups. Enterococcus showed similar resistance patterns in both cohorts, primarily resistant to penicillin and levofloxacin. Conclusion: This study highlights higher resistance rates among Gram-negative bacteria in males to commonly used antibiotics such as fluoroquinolones, trimethoprim/sulfamethoxazole, and β-lactams. Resistance patterns in Gram-positive bacteria remained stable across both populations, with high susceptibility to fosfomycin, nitrofurantoin, linezolid, and carbapenems. Differences between sexes emphasize the need for more detailed analysis of local and sex-specific resistance patterns. Full article

Background: Colistin- and carbapenem-resistant Acinetobacter baumannii (CRAB) represent a critical threat in intensive care unit (ICU) settings. This study aimed to provide a comprehensive molecular epidemiological characterization of extensively drug-resistant (XDR) A. baumannii clinical isolates from a tertiary-care hospital in Kırşehir, Central Anatolia, a region previously absent from the national surveillance literature. Methods: A total of 43 non-duplicate XDR A. baumannii isolates recovered from ICU patients between November 2021 and December 2023 were included. Antimicrobial susceptibility testing was performed by automated systems and broth microdilution for colistin. Resistance genes, including OXA-type carbapenemases, extended-spectrum β-lactamases (ESBLs), metallo-β-lactamases, plasmid-mediated colistin resistance (mcr-1 to mcr-5), plasmid-mediated quinolone resistance genes (qnr, qepA, oqxAB, aac(6′)-Ib-cr), and class 1 and 2 integrons, were screened by PCR. Integron gene cassettes were characterized by sequencing. Clonal relatedness was assessed by pulsed-field gel electrophoresis (PFGE) using ApaI digestion. Results: All 43 isolates exhibited the XDR phenotype with universal resistance to carbapenems, colistin, fluoroquinolones, aminoglycosides (except amikacin), piperacillin, cephalosporins, and tobramycin. Amikacin susceptibility was retained in 58.1% of isolates. blaOXA-51 was detected in all isolates (100%), and blaOXA-23 was the predominant acquired carbapenemase (90.7%). Notably, blaOXA-48, a carbapenemase typically associated with Enterobacteriaceae, was identified in 3 isolates (7.0%), each belonging to a distinct pulsotype. No blaOXA-24/40, blaOXA-58, or class B metallo-β-lactamase genes were detected. ESBL genes were found in a subset of isolates, with blaCTX-M group 1 being the most prevalent (20.9%). The aac(6′)-Ib-cr gene was detected in 81.4% of isolates, and oqxA/oqxB in 60.5% and 39.5%, respectively. No mcr or classical qnr genes were identified. Class 1 and 2 integrons were detected in 4.7% and 7.0% of isolates, respectively, carrying dfrA12-DUF1010-aadA2 (class 1) and dfrA1-sat-1 (class 2) gene cassettes. PFGE identified 12 pulsotypes among the typeable isolates; PT4 (n = 20, 47.6%) and PT11 (n = 8, 19.0%) were the dominant clonal clusters, together accounting for 65.1% of typeable isolates. Conclusions: This study presents one of the first comprehensive molecular epidemiological analyses of XDR A. baumannii from Central Anatolia. The dominance of OXA-23-carrying clonal lineages, the detection of blaOXA-48 in A. baumannii distributed across three distinct pulsotypes, the high prevalence of aac(6′)-Ib-cr, and the concurrent distribution of resistance determinants across genetically diverse clonal backgrounds indicate that both clonal expansion and possible horizontal gene transfer contribute to resistance dissemination in this setting. These findings underscore the need for systematic molecular surveillance and reinforced infection control strategies in ICU settings, at both the regional and national levels. Full article

Poultry is the main reservoir of Campylobacter spp. and most human cases result from consuming undercooked poultry or handling raw meat. In 2022, a total of 55 samples, including neck skin, cecal contents, and processing waters, were collected at two poultry slaughterhouses in Italy and analysed according to ISO 10272-2:2017 at the Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata laboratories. Overall, 51/55 (92.72%) samples tested positive for Campylobacter. Among the isolates, 64.71% were identified as C. coli, and 35.29% as C. jejuni. Phenotypic and genotypic analysis were performed to assess antimicrobial resistance and virulence characteristics. All C. jejuni isolates and 72.72% of C. coli showed resistance to fluoroquinolones. Resistances to tetracycline and carbapenem were observed in 60.78% and 45.09% of isolates, respectively. Genomic analysis confirmed the presence of the tet(O) gene, conferring tetracycline resistance. In addition, OXA-450 and OXA-466 genes, conferring beta-lactam resistance, were detected in 78.43% and 3.92% of isolates. Virulence-associated genes were detected. Specifically, the ciaB gene was found in 50/51 (98.04%) of isolates, whereas jlpA, cdtA, cdtB, and ctdC genes were exclusively identified in C. jejuni strains. The high prevalence of pathogenic and antimicrobial-resistant Campylobacter strains highlights the need for strengthened control measures along the poultry production chain. Full article

Growing resistance to carbapenem antibiotics is a major public health problem as these antibiotics are considered the last line of therapy for infections caused by multidrug-resistant (MDR) Gram-negative bacteria. The rapid emergence and dissemination of carbapenem-resistant bacterial strains are mainly due to horizontal gene transfer (HGT) within or between bacterial cells via the mobilome. The aim of this article is to discuss the role of mobile genetic elements (MGEs) that capture and disseminate resistance determinants of carbapenem antibiotics, as a comprehensive review integrating the combined role of plasmids, transposons and integrons. It attempts to systematically fill the gap by investigating the role of these MGEs in the acquisition, mobilization and dissemination of genes encoding carbapenemases across clinically important bacteria. Various types of plasmids such as IncF and IncH in Klebsiella pneumoniae, IncL/M in Enterobacter cloacae, IncX3 in Escherichia coli and IncA/C₂ in Salmonella enterica carry important genes encoding carbapenemases. The rapid distribution of transposons among bacterial species is one of the main contributing factors in the dissemination of carbapenem-resistant isolates. Transposons including Tn4401 carrying bla_KPC in K. pneumoniae and Tn1721 carrying bla_KPC in E. coli; Tn2006, Tn2007, Tn2008 and Tn2009 carrying bla_OXA-23 in Acinetobacter baumannii; Tn1696 carrying bla_IMP-4 in Pseudomonas aeruginosa; Tn125 carrying bla_NDM in E. coli; and Tn6306 carrying bla_IMI in Raoultella ornithinolytica encode different types of carbapenemases. Integrons mainly belonging to class 1 capture resistance determinants for metallo-carbapenemases such as NDM-, VIM-, SIM- and IMP-type enzymes in P. aeruginosa, A. baumannii, K. pneumoniae and E. coli and can promote the transcription and expression of these determinants. These findings are useful for understanding the genetics of carbapenem resistance and additional knowledge on MGEs may provide avenues for screening of resistance to these antibiotics in clinical settings. Full article

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a significant pathogen for both hospital-acquired and community-acquired infections, characterized by its strong epidemic potential and high mortality rate, posing a severe threat to global public health. CRKP spreads widely across the globe through the horizontal transfer of plasmid-mediated resistance genes such as *blaKPC*, *blaNDM*, and *blaOXA-48*. The clinical treatment options for this bacterium are limited, and its resistance has been increasing year by year, urgently necessitating the development of new antimicrobial drugs or alternative strategies. In recent years, the CRISPR-Cas system has shown great potential in the diagnosis and treatment of CRKP, including rapid detection and identification, gene editing, antimicrobial strategies, and resistance inhibition. For instance, CRISPR-Cas12a/13a can be used for the rapid detection and identification of CRKP, while CRISPR-Cas9/Cas3 can target resistance genes to reverse the resistance of strains. With the advancement of delivery and biotechnologies, the CRISPR-Cas system is expected to become an important tool against drug-resistant CRKP. This review focuses on the application of the CRISPR-Cas system in the detection and treatment of CRKP, analyzing its technical advantages, limitations, and future development directions. Full article

Background/Objectives: Carbapenem-resistant Klebsiella pneumoniae (CRKP) is of great concern because of the difficulties encountered in the management of infections it may cause. This study aims to identify possible difficulties in the management of K. pneumoniae infections in the current context of antibiotic resistance, particularly regarding carbapenem resistance. Methods: This is a retrospective, cross-sectional study that analyses epidemiological, clinical and bacteriological features identified in all patients with CRKP infections/colonization admitted during 2024 in an infectious diseases hospital. Results: Carbapenemase-producing K. pneumoniae isolates were co-harboring NDM+OXA-48 in 55.2% of cases. NDM+OXA-48-producing K. pneumoniae (116 isolates, 55.2%) was correlated with high resistance to aztreonam (100%, p = 0.01), ceftazidime–avibactam (100%, p < 0.01), trimethoprim–sulfamethoxazole (99.1%, p < 0.01), gentamycin (94.8%, p < 0.01), amikacin (93.8%, p < 0.01), colistin (79.8%, p < 0.01). OXA-48-producing K. pneumoniae (29 isolates, 13.8%) was correlated with lower resistance to ceftazidime–avibactam (11.5%, p < 0.01), amikacin (48.1%, p < 0.01), colistin (51.7%, p = 0.01), and gentamycin (65.5%, p < 0.01). We found in vitro synergistic effects of ceftazidime/avibactam + aztreonam for 32/32 CRKP isolates and of colistin + tigecycline for 12/14 CRKP isolates. Higher recurrence of CRKP infections was recorded in patients with urinary tract conditions (RR = 11.58, 95%CI: 1.58–81.91) and upper urinary tract devices (RR = 3.53, 95% CI: 1.72–7.22). In this study, adequate antibiotic treatment, compared to excessive antibiotic treatment in CRKP infections, was associated with shorter treatment duration (p = 0.02) and shorter length of hospitalization (p = 0.04). Conclusions: In our study, CRKP is frequently coharboring NDM+OXA-48, having limited treatment options. Implementing new treatment strategies, testing antibiotic synergies for older antibiotics in order to identify alternative treatment options and avoiding unnecessary carbapenem consumption are essential for decreasing the burden of CRKP infections. Full article

Background/Objectives: Patients in long-term care hospitals (LTCHs) are at increased risk of harboring antimicrobial-resistant organisms due to frequent healthcare exposure and multiple comorbidities. This retrospective observational study aimed to compare the antimicrobial susceptibility of bacterial isolates from LTCH-onset infections (LTCHIs) with those from community-acquired infections (CAIs) in elderly patients. Methods: This study was conducted at a 700-bed urban tertiary university hospital and included patients aged ≥65 years with positive cultures for bacteremia, lower respiratory tract infections (LRTIs), or urinary tract infections (UTIs) within 48 h of admission. Medical records, including antimicrobial susceptibility test results, were reviewed for a total of 1780 patients and their isolates. Antimicrobial susceptibility patterns were compared between LTCHI and CAI patients. Results: Patients with LTCHI exhibited significantly higher antimicrobial non-susceptibility than those with CAIs across multiple pathogens and antimicrobial classes (p < 0.05). In bacteremia, Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae from LTCHI cases showed increased non-susceptibility to β-lactams and fluoroquinolones. In LRTIs, Pseudomonas aeruginosa and Acinetobacter baumannii demonstrated high non-susceptibility to carbapenems (52.9% and 90%, respectively) and aminoglycosides. In UTIs, LTCHI isolates exhibited broader resistance among Enterobacterales and P. aeruginosa. Notably, the proportion of multidrug-resistant organisms, including carbapenem-resistant Enterobacterales (15.4–50.0%) and carbapenem-resistant Acinetobacter baumannii (90.5%), was substantially higher in the LTCHI group across all infection sites. Conclusions: Elderly patients with LTCHI are more likely to harbor antimicrobial-resistant pathogens than those with CAIs. Careful consideration of LTCHI origin is therefore essential for empirical antibiotic selection and for strategies aimed at limiting further resistance. Full article