Search Results (553)

Carbapenem-resistant Klebsiella pneumoniae (CRKP) has become one of the most serious problems confronting modern healthcare, particularly in intensive care units where patients are highly susceptible, procedures are frequent, and antibiotic exposure is often prolonged. In this review, carbapenem resistance in K. pneumoniae is presented not as a fixed feature of individual bacteria, but as a process that is constantly changing and closely interconnected. We bring together evidence showing how the spread of successful bacterial lineages, the exchange of resistance genes, and gradual genetic adjustment combine to drive both the rapid spread and the long-lasting presence of resistance. A major focus is placed on mobile genetic elements, including commonly encountered plasmid backbones, transposons, and insertion sequences that carry carbapenemase genes such as blaKPC, blaNDM, and blaOXA-48-like. These elements allow resistance genes to move easily between bacteria and across different biological environments. The human gut plays a particularly important role in this process. Its microbial community serves as a largely unseen reservoir where resistance genes can circulate and accumulate well before infection becomes clinically apparent, making prevention and control more difficult. This review also discusses the key biological factors that shape resistance levels, including carbapenemase production, changes in the bacterial cell membrane, and systems that expel antibiotics from the cell, and explains how these features work together. Advances in molecular testing have made it possible to identify resistance more quickly, supporting earlier clinical decisions and infection control measures. Even so, current tests remain limited by narrow targets and may miss low-level carriage, hidden genetic reservoirs, or newly emerging resistance patterns. Finally, we look ahead to approaches that move beyond detection alone, emphasizing the need for integrated surveillance, thoughtful antibiotic use, and coordinated system-wide strategies to lessen the impact of CRKP. Full article

Background/Objectives: Water pollution caused by human activities disrupts ecosystems and promotes the spread of antimicrobial resistance genes (ARGs), posing a public health threat. This study investigated the presence of resistant Gram-negative bacteria and resistance genes in water from two sites occasionally exposed to domestic and hospital effluents, the Carioca River (CR) and Rodrigo de Freitas Lagoon (RFL), both used for recreation. Methods: Physicochemical parameters and coliform levels were measured. Bacterial isolates were identified by Matrix-Assisted Laser Desorption Ionization–Time-of-Flight Mass Spectrometry (MALDI-TOF MS) and tested for antimicrobial susceptibility using disk diffusion. The Minimum Inhibitory Concentration (MIC) was determined using the E-test^® and broth microdilution methods. PCR was used to detect carbapenem resistance and other ARGs from the DNA of bacterial isolates obtained from water samples. Results: CR presented signs of environmental degradation, with low dissolved oxygen and high coliform counts. One Citrobacter braakii isolate showed resistance to all tested antimicrobials, raising concern for untreatable infections. Carbapenem-resistant isolates accounted for 49.4% of the total, harboring bla_KPC (20%), bla_TEM (5%), bla_VIM (5%), and bla_SPM (5%). The intl1 gene was found in 10% of isolates, indicating potential horizontal gene transfer. Conclusions: The findings from a one-day sampling reveal the presence of multidrug-resistant bacteria that carry antimicrobial resistance genes in polluted aquatic systems. These highlight the connection between water contamination and antimicrobial resistance. The evidence underscores the urgent need for environmental monitoring and effective management strategies to reduce public health risks. Full article

The rise in antimicrobial resistance (AMR) among the most clinically significant bacteria presents a global threat. The coexistence of resistance mechanisms to both carbapenems and colistin is particularly concerning, as these are last-line treatments, specifically reserved for the most challenging infections caused by clinically multidrug-resistant Enterobacterales. Natural aquatic environments have become environmental reservoirs for the transmission of AMR, particularly concerning mechanisms against these two types of critically important drugs. The crucial role of environmental settings as a driving force for the spread and evolution of AMR associated with these drugs is underestimated, and scientific knowledge on this topic is limited. This review aims to fill an important gap in the scientific literature and comprehensively consolidate the available data on carbapenem- and colistin-associated AMR in the aquatic environment. This study provides a comprehensive synthesis of the current knowledge by integrating bibliographic data with a detailed genomic analysis of 278 bacterial genomes sourced from natural waters. It explores the distribution of carbapenemase and mobile colistin resistance (mcr) genes, identifying their hosts, geographical spread, and complex gene–plasmid–host associations. This review distinguishes two critical host groups for genes that provide resistance to last-resort drugs, Enterobacterales and autochthonous aquatic microbiota, highlighting both confirmed and potential interactions between them. Crucially, genomic analysis highlights the alarming co-occurrence of carbapenem and colistin resistance in single cells and on single plasmids, contributing to the spread of multidrug resistance phenotypes. These findings clearly indicate that aquatic environments are not merely passive recipients but active, evolving hubs for high-risk AMR determinants. Future research should focus on the interplay between allochthonous vectors and autochthonous microbiota to better understand the long-term stabilization of carbapenemase and mcr genes. Such efforts, combined with advanced sequencing technologies, are essential to ensure that carbapenems and colistin remain viable treatment options in clinical settings. Full article

Escherichia coli is an important human pathogen that is able to cause a variety of infections, which can result in diarrhoea, urinary tract infections, sepsis, and even meningitis, depending on the pathotype of the infecting strain. Like many Gram-negative bacteria, E. coli is becoming increasingly resistant to many frontline antibiotics, including third-generation cephalosporins and carbapenems, which are often considered the antibiotics of last resort for these infections. This is particularly the case in Egypt, where multidrug-resistant (MDR) E. coli is highly prevalent. However, in spite of this, few Egyptian MDR E. coli strains have been fully characterised by genome sequencing. Here, we present the genome sequences of ten highly MDR E. coli strains, which were isolated from children who presented with diarrhoea at the Outpatients Clinic of Assiut University Children’s Hospital in Assiut, Egypt. We report that they carry multiple antimicrobial resistance genes, which includes extended spectrum β-lactamase genes, as well as bla_NDM and bla_OXA carbapenemase genes, likely encoded on IncX3 and IncF plasmids. Many of these strains were also found to be high-risk extra-intestinal pathogenic E. coli (ExPEC) clones belonging to sequence types ST167, ST410, and ST617. Thus, their presence in the Egyptian paediatric population is particularly worrying, and this highlights the need for increased surveillance of high-priority pathogens in this part of the world. Full article

Antimicrobial resistance (AMR) is a global threat to human, animal and environmental health, underscoring the need for integrated surveillance to understand its dynamics and ecosystem interactions. This study investigated the potential of swifts (Apus spp.), long-distance migratory birds, as valuable bioindicators of environmental AMR dissemination. Four sampling sessions were conducted over two years (2023–2024) at a wildlife rehabilitation center in Trieste, Italy. Buccal and cloacal swabs were collected from 47 swifts: 10 sampled at arrival and 37 before autumn migration. Swabs were streaked on selective media for targeted isolation of Enterobacterales, Bacillales and Lactobacillales, yielding 168 bacterial isolates. Bacteria were identified using MALDI-TOF and antimicrobial susceptibility was assessed through disk diffusion method, using ECOFFs values or “no inhibition zone” criterion. Of the 168 bacterial isolates, 51 (30.36%) were non-wild type (NWT), with highest percentages of NWT isolates for clarithromycin (33.33%), erythromycin (31.50%), clindamycin (21.88%) and tetracycline (14.29%). Methicillin-resistant staphylococci (45.83%) and carbapenem NWT isolates (9.38%) were also detected. Bacillales isolates showed significantly higher NWT proportion (58.33%; p < 0.0001) compared to Enterobacterales and Lactobacillales. These findings, in clinically healthy non-antimicrobial treated swifts, suggest environmental exposure to resistant bacteria, and support a possible role of swifts as bioindicators of environmental AMR contamination, highlighting the need to strengthen environmental AMR surveillance within a One Health perspective. Full article

Quality control of drinking water is essential for safeguarding public health, particularly in densely populated urban environments. Environmental microbiological monitoring can complement conventional surveillance by providing deeper insights into the dissemination of pathogens and antimicrobial resistance genes within aquatic systems. In this study, we assessed the quality of wastewater and treated water from two urban water supply systems, representing the southern and northern regions of Porto Alegre, Rio Grande do Sul, Brazil, across four climatic seasons between 2024 and 2025. Fifteen water samples were analyzed, including raw water from Guaíba Lake and treated water collected from public distribution points. The Water Quality Index was calculated, microbiological indicators were quantified, and carbapenem resistance genes were detected using molecular assays. Most treated water samples complied with established bacteriological standards; however, the bla_OXA-48-like gene was recurrently detected in both wastewater and treated water. No resistance genes were identified during the summer, whereas the bla_VIM gene was detected exclusively in spring samples. The presence of carbapenem resistance genes in the absence of cultivable coliforms suggests the persistence of extracellular DNA or viable but non-culturable bacteria, highlighting limitations inherent to conventional microbiological monitoring. Integrating classical microbiological methods with molecular assays enables a more comprehensive assessment of water quality and strengthens evidence-based decision-making within a One Health framework. Full article

Recycled wastewater is vital for the circular economy, especially on water-scarce islands. This study explored the presence of Carbapenem-Resistant Enterobacterales and other emerging pathogens in irrigation water on four Canarian Islands, applying a One Health perspective. Using membrane filtration and MALDI-TOF mass spectrometry, 69 bacterial isolates were identified. The findings revealed that 78% were Gram-negative bacilli like Pseudomonas aeruginosa, Acinetobacter spp., Enterobacteriaceae, etc., while 22% were Gram-positive bacteria, including Enterococcus spp. The main mechanisms of carbapenem resistance in Pseudomonas spp. and Acinetobacter spp. were oxacillinases, followed by metallo-β-lactamases (MBL). In Enterobacteriaceae, characterization of carbapenemase types was less frequent, with oxacillinase 48 (OXA-48) being the most prevalent. The detection of multidrug-resistant organisms in recycled wastewater highlights an urgent need for routine microbiological monitoring in water management to protect both public health and agricultural sustainability. Full article

Antimicrobial resistance in urinary tract infections (UTIs) poses a critical public health challenge, yet comparative data between outpatient and inpatient settings remain limited, particularly in Latin America. This study characterized the epidemiology, microbiology, and resistance patterns of UTIs in northwestern Mexico. A retrospective analysis of 1041 patients with UTI (May–November 2024) was conducted. Microorganism identification and antimicrobial susceptibility were determined using the MicroScan WalkAway system in accordance with CLSI guidelines. Results: Outpatients accounted for 80.5% of cases and inpatients for 19.4%, with a 3.1% mortality rate. Escherichia coli predominated (62.9%), with a significant association with outpatients (p = 0.02), whereas Enterobacter cloacae, Acinetobacter spp., Candida tropicalis, and C. albicans were associated with inpatients (p < 0.05). Pediatric patients exhibited distinctive microbiological profiles: Pseudomonas aeruginosa (9.7% vs. 2.1%, p = 0.032), Enterococcus faecalis (33.3% vs. 16.2%, p = 0.001), and Staphylococcus epidermidis (26.6% vs. 6.5%, p = 0.027) were significantly more prevalent than in adults. Multidrug resistance (MDR) was detected in 27.1% of isolates, and extensive drug resistance (XDR) in 3.2%. XDR was associated with Gram-positive bacteria (12.2% vs. 1.4%, p < 0.001). Carbapenem-resistant Enterobacteriaceae (CRE) were identified in 0.9% (7/772) of cases, with 42.9% occurring in outpatients. Hospitalization (OR: 2.01; 95% CI: 1.43–2.83), surgical services (OR: 1.41; 95% CI: 1.02–1.97), and recent surgery (OR: 2.37; 95% CI: 1.04–5.39) were independent predictors of MDR/XDR infections. Conclusions: These findings demonstrate the emergence of CRE within the community and distinctive pediatric resistance patterns, underscoring the need for tailored antimicrobial stewardship strategies in this region. Full article

Background/Objectives: Healthcare-associated infections (HAIs), particularly those caused by multidrug-resistant (MDR) bacteria, remain a major challenge for Romanian hospitals. This study aimed to evaluate the epidemiological burden of MDR-related HAIs and to characterize the distribution of MDR bacterial isolates and their antimicrobial resistance patterns over four consecutive semesters in a Romanian tertiary care hospital. Methods: A retrospective study was conducted using data from the Electronic Registry of HAIs, clinical observation sheets, and microbiology laboratory records. An epidemiological analysis was performed on patients diagnosed with MDR-related HAIs, while a separate microbiological analysis included all MDR bacterial isolates identified during the study period. Descriptive and comparative statistical analyses were applied to assess temporal trends, pathogen distribution, and resistance profiles. Results: Of the 327 HAIs identified, 56 cases (17.13%) were caused by MDR bacteria. Most MDR-HAIs originated from the Intensive Care Unit (≈60%), with Acinetobacter baumannii and Klebsiella spp. as the predominant pathogens. Overall mortality among patients with MDR-HAIs was high (51.79%), particularly in infections caused by A. baumannii and K. pneumoniae. Microbiological analysis of MDR isolates (n = 406) revealed consistently high resistance rates to ciprofloxacin, cefepime, and ceftazidime, exceeding 95% in 2023–2024, while resistance to carbapenems surpassed 90% by the end of the study period. Temporal variability in MDR burden was observed across semesters, suggesting an influence of clinical and institutional factors. Conclusions: MDR-related HAIs represent a significant and persistent problem in Romanian acute-care hospitals, particularly in Intensive Care Units. The dominance of carbapenem-resistant A. baumannii and extended-spectrum beta-lactamase-producing and carbapenem-resistant Klebsiella spp. highlights the urgent need for strengthened antimicrobial stewardship, enhanced microbiological surveillance, and reinforced infection prevention strategies. Full article

Emerging antimicrobial resistance (AMR) in companion animals represents a global health concern as they serve as potential reservoirs for multidrug-resistant (MDR) bacteria, which can be transmitted to humans. Herein, we provide comprehensive surveillance data on resistance patterns in veterinary hospital settings, focusing on urinary tract infection. A total of 23 bacterial strains were isolated from urine specimens of hospitalized companion animals suspected of urinary tract infections (UTIs) between 2022 and 2024. 16S rRNA sequencing analysis revealed that Escherichia coli (47.8%), Klebsiella pneumoniae (21.7%), and Pseudomonas aeruginosa (8.7%) were predominant uropathogens. Minimum inhibitory concentration and minimum bactericidal concentration tests were employed to analyze AMR patterns across different classes of antibiotics. Moreover, antimicrobial susceptibility test exhibited 73.91% MDR according to the standard definition given by the Clinical and Laboratory Standards Institute (CLSI) M100 guidelines. Most Gram-negative bacteria have been shown to be resistant to beta-lactam antibiotics, especially carbapenems. Notably, an E. coli strain was confirmed to possess the bla_NDM-1 gene encoding the carbapenemase New Delhi metallo-β-lactamase. These findings support the implementation of targeted infection control measures and evidence-based treatment protocols to preserve antimicrobial efficacy in companion animal medicine to minimize potential public health risks through the One Health approach. Full article

Background/Objectives: Antimicrobial resistance (AMR) in wildlife is an emerging public health concern due to the risk of zoonotic transmission, especially through the food chain, yet data on free-ranging animals remain scarce. This study examined the presence and patterns of AMR among bacteria isolated from hunted wild boars in the Campania region of Italy. Methods: Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) was used to identify bacterial isolates from wild boar meat and carcass swabs to the species level, and the Kirby–Bauer disk diffusion test was applied to screen 205 isolates, spanning 20 bacterial genera, against a panel of clinically relevant antibiotics. Resistance metrics were analyzed at genus and antibiotic levels, and patterns were visualized using a hierarchically clustered heatmap. Results: Resistance was detected in 15 of the 20 genera, with full susceptibility observed in Acinetobacter, Arthrobacter, Glutamicibacter, Leclercia, and Rahnella. Overall, 67.3% (138/205) of the isolates showed resistance to at least one antibiotic, with 33.7% (69/205) classified as multidrug-resistant (MDR). Carbapenems retained the highest activity (≥95% susceptibility) among all genera tested, while amoxicillin/clavulanate (78.4%) and aztreonam (57.4%) exhibited the highest mean resistance. Among potential pathogens, Escherichia coli exhibited an extended-spectrum β-lactamase (ESBL)-like phenotype, with resistance to amoxicillin/clavulanate (67%), aztreonam (54%), and ceftazidime (47%) but preserved carbapenem susceptibility. Staphylococcus spp. showed pronounced resistance to linezolid (57%) and erythromycin (52%), whereas Pseudomonas isolates demonstrated elevated resistance to aztreonam and ceftazidime (57% each). Opportunistic pathogens such as Alcaligenes faecalis and Pantoea agglomerans showed peak resistance to ciprofloxacin and amoxicillin/clavulanate. Pathogens and opportunistic pathogens demonstrated higher mean resistance (>30%) than commensals (≤32%), but the difference in mean and median resistance levels was not statistically significant (Mann–Whitney’s U test, W = 4, p = 0.39). Conclusions: These findings highlight the widespread occurrence of AMR and MDR phenotypes, with clinically significant resistance patterns in wild-boar-associated bacteria, including non-pathogenic strains, highlighting their role in the amplification of AMR. Although the preservation of carbapenem susceptibility underscores their potential as last-line antibiotics, the high resistance to commonly used antibiotics raises concerns for zoonotic transmission. Surveillance of wildlife reservoirs therefore remains critical for integrated AMR control. Full article

Background: Globalization, increased mobility, changes in dietary habits, and a growing number of immunocompromised patients have heightened exposure to rare or opportunistic pathogens. Here, we present a case of cardiac implantable electronic device-related infective endocarditis (CIED-IE) caused by Bacillus cereus bacteremia originating in the gastrointestinal tract. Case presentation: A 66-year-old female, who had a cardiac resynchronization pacemaker (CRT-P) implanted in 2017 due to second-degree atrioventricular block and left bundle branch block, had undergone device replacement due to battery depletion 4 months earlier and was scheduled for transvenous lead extraction (TLE) due to generator pocket infection. During the TLE procedure, transoesophageal echocardiography revealed vegetations on the leads and in the right atrium. Standard empirical therapy covering methicillin-resistant Staphylococci and Gram-negative bacteria was administered, including oritavancin and gentamicin. Surprisingly, intraoperative samples cultured B. cereus, a Gram-positive, spore-forming rod that usually causes food poisoning through contamination of rice and other starchy foods. B. cereus is generally resistant to β-lactam antibiotics except for carbapenems but is susceptible to glycopeptides. The oritavancin treatment was extended to four fractionated doses (1200, 800, 800, and 800 mg) administered at 7-day intervals. To eradicate bacteria in the gastrointestinal tract, oral vancomycin (125 mg 4 times a day) was added. After 4 weeks of effective antibiotic therapy, a CRT-P with a left bundle branch area pacing lead was reimplanted on the right subclavian area, with no recurrence of infection during the 3-month follow-up. Clinical discussion: In the patient, a diet high in rice and improper storage of rice dishes, together with habitual constipation, were identified as risk factors for the development of invasive Bacillus cereus infection. However, the long half-life lipoglycopeptide antibiotic, oritavancin, administered weekly, proved effective in treating CIED-IE. Conclusions: Infection with rare or opportunistic microorganisms may require extended microbiological diagnostics and non-standard antibiotic therapy; therefore, the medical history should consider risk factors for such infections. Full article

Stenotrophomonas maltophilia bloodstream infection (SM-BSI) carries high mortality and limited therapeutic options. We conducted a single-center retrospective cohort of adults with first SM-BSI (2018–2024) to describe treatment patterns and identify factors associated with survival. Demographic, clinical, and microbiological data were extracted and analyzed. Forty-three patients were included (median age: 63 years; 61% male). Appropriate antimicrobial therapy was given to 74%; trimethoprim–sulfamethoxazole-based regimens were used in 61%; and combination therapy in 23%. The median time from BSI to treatment initiation was 4 days (IQR: 3–5) and the treatment duration averaged 7 days (IQR: 0–12). Thirty-day mortality was 37% (16/43). The survival analysis found that a 14–21-day course was associated with better 30-day survival than a 7–13-day course (0/9 vs. 5/15 deaths; log-rank p = 0.045), whereas monotherapy and combination therapy did not differ (p = 0.855). Multidrug resistance was linked to worse survival (log-rank p = 0.001). In multivariable models for 30-day mortality, only active treatment (aHR: 0.14; 95% CI: 0.02–0.88) and microbiological cure (aHR: 0.08; 95% CI: 0.01–0.47) remained independently protective. These data suggest that outcomes in SM-BSI are driven primarily by the receipt of appropriate therapy and achievement of microbiological clearance, reinforcing the need for prompt source control, optimized antimicrobial treatment, and continued development of novel therapeutic strategies to improve outcomes in this challenging infection. Full article

Acinetobacter baumannii (A. baumannii) is an opportunistic pathogen associated with healthcare-related infections and is of particular concern due to its high level of antibiotic resistance and its ability to form biofilms. The global emergence of carbapenem-resistant A. baumannii highlights the urgent need for alternative therapeutic strategies. This study investigated the antibacterial and antibiofilm activities of two scorpion venom-derived peptides, pantinin-1 and pantinin-2, against a reference strain and a clinical isolate of A. baumannii. We found that both peptides, in the non-cytotoxic concentration range, have strong bactericidal activity, showing a minimum inhibitory concentration (MIC) of 6.25 μM and 12.5 μM for pantinin 1 and 2, respectively. Scanning electron microscopy (SEM) analysis showed that the peptides cause extensive damage to the bacterial membrane. Furthermore, both peptides showed potent antibiofilm activity, inhibiting adhesion and maturation, arresting biofilm expansion, and reducing the expression of key biofilm-associated genes (bap, pgaA, and smpA). Altogether, these findings indicate that pantinin-1 and pantinin-2 act through a dual mechanism, combining bactericidal and antivirulence activities. Their strong efficacy at low micromolar concentrations, together with low cytotoxicity, underscores their potential as innovative therapeutic candidates against infections caused by carbapenem-resistant, biofilm-forming A. baumannii. Full article

It is crucial to identify Enterobacterales that produce carbapenemase to treat and manage hospital infections. The suggested techniques for their identification need a lengthy wait, technical knowledge, and training. Lateral flow immunoassays (LFIAs) provide a solution to these requirements. Thus, this study compared LFIA with phenotypic and genotypic tests for carbapenemase-producing bacteria. Fifty clinical isolates of carbapenem-resistant superbugs were examined. KPC, VIM, NDM, IMP, and OXA-48-like enzymes were evaluated and compared with phenotypic tests and LFIA. Regarding the phenotypic characteristics, the mCIM was positive in 37/50 (74%), and the eCIM was positive in 21/50 (42%). Regarding using LFIA, 41 out of the total isolates (82%) gave a positive red line with one or more of the tested genes. The most frequently detected gene was bla_NDM (27/50 (54%)), and the least detected one was bla_IMP (14/50 (28%)), which was in accordance with the PCR results. While investigating the accuracy of LFIA vs. PCR, it was found that LFIA had 100% sensitivity in the detection of the bla_NDM and bla_OXA genes, with 85.2% and 91.4% specificity, respectively, while for the bla_IMP, bla_KPC, and bla_VIM genes, the values were 91.7% and 92.1%, 94.1% and 90.9%, and 95.5% and 89.3%, respectively. The overall accuracy of LFIA ranged from 92 to 94%. Our comparison with molecular assays revealed remarkable agreement, so we propose that this test might be utilized as a supplementary tool. Full article