Hospital-acquired Pathogens Research Articles

Modular, inducible, and titratable expression systems for Escherichia coli and Acinetobacter baumannii.

Gene expression systems that transcend species barriers are needed for cross-species analysis of gene function. In particular, expression systems that can be utilized in both model and pathogenic bacteria underpin comparative functional approaches that inform conserved and variable features of bacterial physiology. In this study, we develop replicative and integrative vectors alongside a novel, IPTG-inducible promoter that can be used in the model bacterium Escherichia coli K-12 as well as strains of the antibiotic-resistant pathogen, Acinetobacter baumannii. We generate modular vectors that transfer by conjugation at high efficiency and either replicate or integrate into the genome, depending on design. Embedded in these vectors, we also developed a synthetic, IPTG-inducible promoter, PabstBR, that induces to a high level but is less leaky than the commonly used trc promoter. We show that PabstBR is titratable at both the population and single-cell levels, regardless of species, highlighting the utility of our expression systems for cross-species functional studies. Finally, as a proof of principle, we use our integrating vector to develop a reporter for the E. coli envelope stress σ factor, RpoE, and deploy the reporter in E. coli and A. baumannii, finding that A. baumannii does not recognize RpoE-dependent promoters unless RpoE is heterologously expressed. We envision that these vector and promoter tools will be valuable for the community of researchers who study the fundamental biology of E. coli and A. baumannii.IMPORTANCEAcinetobacter baumannii is a multidrug-resistant, hospital-acquired pathogen with the ability to cause severe infections. Understanding the unique biology of this non-model bacterium may lead to the discovery of new weaknesses that can be targeted to treat antibiotic-resistant infections. In this study, we provide expression tools that can be used to study the gene function in A. baumannii, including in drug-resistant clinical isolates. These tools are also compatible with the model bacterium, Escherichia coli, enabling cross-species comparisons of gene function. We anticipate that the use of these tools by the scientific community will accelerate our understanding of Acinetobacter biology.

Antimicrobial resistance profile and associated factors of hospital-acquired gram-negative bacterial pathogens among hospitalized patients in northeast Ethiopia

BackgroundAntimicrobial resistance is a major global public health issue. Infections caused by resistant species are associated with higher mortality rates, longer hospital stays, medication failure, and rising medical costs. The World Health Organisation has declared multidrug resistance-associated infections as an epidemic of public health concern.ObjectiveThis study aimed to evaluate the antimicrobial resistance profile and associated factors of hospital-acquired Gram-negative bacterial pathogens among hospitalized patients in Northeast Ethiopia.Materials and methodsA health facility-based cross-sectional study was conducted among hospitalized patients from March 2021 to February 2022. About 810 clinical specimens were collected, transported, and processed from admitted patients following the standard bacteriological procedures. The clinical samples were inoculated onto blood agar, MacConkey agar, and chocolate agar. Furthermore, the species identification was done using gram reactions, colony morphology, and color and biochemical tests. Antimicrobial susceptibility tests, extended-spectrum beta-lactamase, and carbapenemase production were performed as per the clinical laboratory standard institute guidelines. For analysis, the information was entered into Epi-data and exported to SPSS. A P value of < 0.05 with a 95% confidence interval was considered as a statistically significant association.ResultsOut of 810 clinical specimens, 285/810 (35.2%) developed bacterial infections. From the isolated bacteria, E. coli was the predominant bacteria accounting for 78/285 (27.4%) followed by K. pneumoniae, 69/285(24.42%), whereas P. vulgaris accounted for the least, 7/285 (2.5%). Overall, 132/285 (46.3%) and 99/285 (34.7%) of culture-positive patients were infected by extended-spectrum beta-lactamase and carbapenemase-producing bacteria. The overall multidrug resistance rate of the isolated bacteria was 89.4%. The highest antibiotic resistance rates were detected for doxycycline (92.9%), amoxicillin-clavulanic acid (83.9%), and ampicillin (93%). The least antibiotic resistance rate was observed for meropenem at 41.1% and amikacin at 1.7%, respectively.Conclusions and recommendationsIn the study area, significant health concerns include a range of hospital-acquired bacterial infections associated with elevated rates of multidrug resistance, Extended-spectrum beta-lactamase (ESBL), and carbapenemase-producing bacterial pathogens. Consequently, it is recommended to conduct drug-susceptibility testing of isolates and molecular detection at a national level to optimize antibiotic usage for treating prevalent bacterial infections in this area.

Acinetobacter pittii: the emergence of a hospital-acquired pathogen analyzed from the genomic perspective.

Acinetobacter pittii has increasingly been associated with several types of hospital-acquired severe infections. Genes implicated in carbapenem resistance, tigecycline resistance, or genes encoding extended spectrum cephalosporinases, such as blaADC, are commonly found in isolates implicated in these infections. A. pittii strains that are pandrug resistant have occasionally been identified. Food for human consumption, animals and plants are environmental sources of this pathogen. An alarming situation is that A. pitti has been identified as responsible for outbreaks in different regions worldwide. In this study, 384 genomes of A. pittii were analyzed, comprising sequences from clinical and non-clinical origins from 32 countries. The objective was to investigate if clinical strains possess genetic traits facilitating hospital adaptation. Results indicate significant genomic variability in terms of size and gene content among A. pittii isolates. The core genome represents a small portion (25-36%) of each isolate's genome, while genes associated with antibiotic resistance and virulence predominantly belong to the accessory genome. Notably, antibiotic resistance genes are encoded by a diverse array of plasmids. As the core genome between environmental and hospital isolates is the same, we can assume that hospital isolates acquired ARGs due to a high selective pressure in these settings. The strain's phylogeographic distribution indicates that there is no geographical bias in the isolate distribution; isolates from different geographic regions are dispersed throughout a core genome phylogenetic tree. A single clade may include isolates from extremely distant geographical areas. Furthermore, strains isolated from the environment or animal, or plant sources frequently share the same clade as hospital isolates. Our analysis showed that the clinical isolates do not already possess specific genes, other than antibiotic-resistant genes, to thrive in the hospital setting.

The prevalence of hospital acquired infection and associated factors among patients admitted at Wolaita Sodo University Comprehensive Specialized Hospital, in Ethiopia

Hospital-acquired infection is an infection acquired a major global concern of well-being, affecting the quality of care in the healthcare setting. Routine surveillance of infection is an important part of infection prevention and quality assurance in hospitals. to determine the prevalence and associated factors of hospital-acquired infection among inpatients, in Wolaita Sodo University Comprehensive Specialized Hospital.Across-sectional study was conducted among inpatients in Wolaita Sodo University Comprehensive Specialized Hospital. All eligible inpatients admitted at least more three days of the survey were included. The study was conducted from April 1 to July 30/2023. Environmental health professionals and nurses collected the data according to the Centers for Disease Control through observational assessments documented by physicians. Univariate and multivariable logistic regression analyses were used to determine the prevalence of hospital-acquired infections and the associations between independent and dependent variables. A total of 413 patients were included in this study, the median age of the participants was 26 years. A total of 352 (85.2%) patients were diagnosed with non-fatal disease during the survey. 49 patients had hospital-acquired infections developed, with a mean prevalence of 11.9 %. Coagulate-negative staphylococcus 27.27%), and E. coli (27.27) were the most frequently reported hospital-acquired infection-causing pathogens from the result of the study. The factors of patient admission diagnosis, length of hospital stay (more than five days of hospital stay), and absence of running tap water in the patient’s room with the occurrence of hospital-acquired infection were statistically significant.Surgical site infections and bloodstream infections were the most common types of hospital-acquired infections. Then, Hospital management and healthcare workers should give more attention to the practice of infection prevention to achieve a reduced prevalence of hospital-acquired infections in the study setting.

Generation and Characterization of Stable Small Colony Variants of USA300 Staphylococcus aureus in RAW 264.7 Murine Macrophages.

Intracellular survival and immune evasion are typical features of staphylococcal infections. USA300 is a major clone of methicillin-resistant S. aureus (MRSA), a community- and hospital-acquired pathogen capable of disseminating throughout the body and evading the immune system. Carnosine is an endogenous dipeptide characterized by antioxidant and anti-inflammatory properties acting on the peripheral (macrophages) and tissue-resident (microglia) immune system. In this work, RAW 264.7 murine macrophages were infected with the USA300 ATCC BAA-1556 S. aureus strain and treated with 20 mM carnosine and/or 32 mg/L erythromycin. Stable small colony variant (SCV) formation on blood agar medium was obtained after 48 h of combined treatment. Whole genome sequencing of the BAA-1556 strain and its stable derivative SCVs when combining Illumina and nanopore technologies revealed three single nucleotide differences, including a nonsense mutation in the shikimate kinase gene aroK. Gene expression analysis showed a significant up-regulation of the uhpt and sdrE genes in the stable SCVs compared with the wild-type, likely involved in adaptation to the intracellular milieu.

“The end of the era of antibiotics” — myth or reality: what the past COVID-19 pandemic has shown

BACKGROUND: During the coronavirus disease 2019 pandemic, the sale of antimicrobials (AMPs) in the pharmacy network and their purchases by healthcare facilities of the Russian Federation have significantly increased. Microbiological monitoring conducted at the City Clinical Hospital No. 67 named after L.A. Vorokhobov of the Moscow Health Department in 2020–2021 revealed an urgent problem: gram-negative bacteria, which are dominated by multidrug-resistant (MDR) strains, are now mainly isolated from patients with healthcare-associated infections (HAIs). Pharmacoeconomic studies have shown that the cost of one course of targeted antibiotic therapy for HAIs can increase by 6–12 times compared with a similar course of therapy in the absence of nosocomial MDR and extensively drug-resistant (XDR) pathogens.&#x0D; AIM: To increase the effectiveness of preventive measures aimed at preventing the spread of hospital-acquired pathogen strains in the intensive care unit (ICU) using effective bacteriophages against MDR strains of Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, and Acinetobacter baumannii, which were selected in accordance with an individualized algorithm.&#x0D; MATERIALS AND METHODS: The study included two groups, totaling 20 patients, who were on prolonged mechanical ventilation in the ICU of City Clinical Hospital No. 67 named after L.A. Vorokhobov of the Moscow Health Department in 2022. The second group received 20 mL of bacteriophages via an intragastric tube for five consecutive days. The concept of a personalized approach to phage therapy for various forms of HAIs caused by nosocomial MDR pathogens in patients of a multidisciplinary hospital has been proposed and tested.&#x0D; RESULTS: With this medical technology, the effectiveness of phage therapy for various nosological forms of HAIs caused by nosocomial MDR and XDR strains increased by 30%, and the effectiveness of the initial antibiotic therapy regimen was ≥70%. The economic effect of the combination of antibiotic therapy and phage therapy (booster therapy) amounted to more than 3 million rubles compared with the use of AMP alone for treating patients with HAIs caused by nosocomial MDR/XDR strains.&#x0D; CONCLUSIONS: Booster therapy as a variant of IIB therapy reduces the cost of treatment of AMPs of various forms of HAIs by ≥2.5 times compared with AMPs alone.

Exceptions to the rule: When does resistance evolution not undermine antibiotic therapy in human bacterial infections?

The use of antibiotics to treat bacterial infections often imposes strong selection for antibiotic resistance. However, the prevalence of antibiotic resistance varies greatly across different combinations of pathogens and drugs. What underlies this variation? Systematic reviews, meta-analyses, and literature surveys capable of integrating data across many studies have tried to answer this question, but the vast majority of these studies have focused only on cases where resistance is common or problematic. Yet much could presumably be learned from the cases where resistance is infrequent or absent. Here we conducted a literature survey and a systematic review to study the evolution of antibiotic resistance across a wide range of pathogen-by-drug combinations (57 pathogens and 53 antibiotics from 15 drug classes). Using Akaike information criterion-based model selection and model-averaged parameter estimation we explored 14 different factors posited to be associated with resistance evolution. We find that the most robust predictors of high resistance are nosocomial transmission (i.e., hospital-acquired pathogens) and indirect transmission (e.g., vector-, water-, air-, or vehicle-borne pathogens). While the former was to be expected based on prior studies, the positive correlation between high resistance frequencies and indirect transmission is, to our knowledge, a novel insight. The most robust predictor of low resistance is zoonosis from wild animal reservoirs. We also found partial support that resistance was associated with pathogen type, horizontal gene transfer, commensalism, and human-to-human transmission. We did not find support for correlations between resistance and environmental reservoirs, mechanisms of drug action, and global drug use. This work explores the relative explanatory power of various pathogen and drug factors on resistance evolution, which is necessary to identify priority targets of stewardship efforts to slow the spread of drug-resistant pathogens.

Short-chain fatty acids of various lengths differentially inhibit Klebsiella pneumoniae and Enterobacteriaceae species.

The gut microbiota is inextricably linked to human health and disease. It can confer colonization resistance against invading pathogens either through niche occupation and nutrient competition or via its secreted metabolites. Short-chain fatty acids (SCFA) are the primary metabolites in the gut as a result of dietary fiber fermentation by the gut microbiota. In this work, we demonstrate that the interaction of single-species gut commensals on solid media is insufficient for pathogen inhibition, but supernatants from monocultures of these commensal bacteria enriched in acetate confer inhibition against anaerobic growth of the enteric pathogen Klebsiella pneumoniae. The three primary SCFAs (acetate, propionate, and butyrate) strongly inhibit the intestinal commensal Escherichia coli Nissle as well as a panel of enteric pathogens besides K. pneumoniae at physiological pH of the cecum and ascending colon. This inhibition was significantly milder on anaerobic gut commensals Bacteroides thetaiotaomicron and Bifidobacterium adolescentis previously demonstrated to be associated with microbiota recovery after antibiotic-induced dysbiosis. We describe a general suppression of bacterial membrane potential by these SCFAs at physiological cecum and ascending colonic pH. Furthermore, the strength of bacterial inhibition increases with increasing alkyl chain length. Overall, the insights gained in this study shed light on the potential therapeutic use of SCFAs for conferring colonization resistance against invading pathogens in a dysbiotic gut.IMPORTANCERising antimicrobial resistance has made treatment of bacterial infections increasingly difficult. According to the World Health Organization, it has become a burgeoning threat to hospital and public health systems worldwide. This threat is largely attributed to the global rise of carbapenem-resistant Enterobacteriaceae in recent years, with common hospital-acquired pathogens growing increasingly resistant to last-line antibiotics. Antibiotics disrupt the homeostatic balance of the gut microbiota, resulting in the loss of colonization resistance against enteric pathogens. This work describes the ability of short-chain fatty acids (SCFAs) produced by gut microbiota to be effective against a wide panel of enteric pathogens without major impact on common gut commensal species. We also demonstrate a previously undescribed link between alkyl chain length and antibacterial effects of SCFAs. SCFAs, thus, hold promise as an alternative therapeutic option leveraging on the antimicrobial activity of these endogenously produced gut metabolites without disrupting gut microbiota homeostasis.

Present Strategy and Tactics of Antibacterial Therapy for Hospital Infections: Lessons Learned from the COVID-19 Pandemic

A significant increase in sales of antibacterial drugs in pharmacies and their purchases by medical institutions of the Russian Healthcare System was observed against the background of the past pandemic of a novel coronavirus infection in Russia. Microbiological monitoring that was carried out at City Clinical Hospital No. 67 named after. L. A. Vorokhobov (Moscow) in 2020–2021, revealed a pressing problem — primarily gram-negative bacteria, with a predominance of multidrug-resistant (MDR) strains, were isolated from patients with healthcare-associated infections (HAIs). As shown by pharmacoeconomic studies conducted by the authors, the cost of one course of targeted antibacterial therapy for HAI in this case could increase by 6–12 times compared to a similar course of therapy in the absence of both MDR strains and XDR strains of hospital pathogens. In order to achieve a reduction in the cost of antibacterial therapy developed and used by the authors, in addition to the development of effective antibacterial therapy regimens for HAIs caused by MDR/XDR pathogens, another study was carried out as a continuation of the work on creating and improving biotherapy regimens for HAIs, namely the development of personalized phage therapy regimens for patients with hospital-acquired pneumonia caused by MDR bacterial strains. Based on the data obtained, the concept of a personalized approach to phage therapy of various nosological forms of HAIs caused by hospital-acquired MDR pathogens in patients of a multidisciplinary hospital was proposed and tested. As a result of this approach, the effectiveness of phage therapy for various nosological forms of HAIs caused by MDR and XDR strains of hospital pathogens in City Clinical Hospital No. 67 named after. L. A. Vorokhobov increased by 30%, and the effectiveness of the initial antibiotic regimen was 70%. The economic effect of the combination of antibiotic therapy and phage therapy («booster therapy») amounted to 3,000,000 rubles, compared with the use of antibiotics alone in the treatment of patients with HAIs caused by MDR/XDR strains of hospital pathogens.

Regional patient transfer patterns matter for the spread of hospital-acquired pathogens

Pathogens typically responsible for hospital-acquired infections (HAIs) constitute a major threat to healthcare systems worldwide. They spread via hospital (or hospital-community) networks by readmissions or patient transfers. Therefore, knowledge of these networks is essential to develop and test strategies to mitigate and control the HAI spread. Until now, no methods for comparing healthcare networks across different systems were proposed. Based on healthcare insurance data from four German federal states (Bavaria, Lower Saxony, Saxony and Thuringia), we constructed hospital networks and compared them in a systematic approach regarding population, hospital characteristics, and patient transfer patterns. Direct patient transfers between hospitals had only a limited impact on HAI spread. Whereas, with low colonization clearance rates, readmissions to the same hospitals posed the biggest transmission risk of all inter-hospital transfers. We then generated hospital-community networks, in which patients either stay in communities or in hospitals. We found that network characteristics affect the final prevalence and the time to reach it. However, depending on the characteristics of the pathogen (colonization clearance rate and transmission rate or even the relationship between transmission rate in hospitals and in the community), the studied networks performed differently. The differences were not large, but justify further studies.

Study of the Antibacterial Activity of Superhydrophilic and Superhydrophobic Copper Substrates against Multi-Drug-Resistant Hospital-Acquired Pseudomonas aeruginosa Isolates.

The global spread of multidrug-resistant (MDR) hospital-acquired pathogens is a serious problem for healthcare units. The challenge of the spreading of nosocomial infections, also known as hospital-acquired pathogens, including Pseudomonas aeruginosa, must be addressed not only by developing effective drugs, but also by improving preventive measures in hospitals, such as passive bactericidal coatings deposited onto the touch surfaces. In this paper, we studied the antibacterial activity of superhydrophilic and superhydrophobic copper surfaces against the P. aeruginosa strain PA103 and its four different polyresistant clinical isolates with MDR. To fabricate superhydrophilic and superhydrophobic coatings, we subjected the copper surfaces to laser processing with further chemosorption of fluorooxysilane to get a superhydrophobic substrate. The antibacterial activity of superhydrophilic and superhydrophobic copper surfaces was shown, with respect to both the collection strain PA103 and polyresistant clinical isolates of P. aeruginosa, and the evolution of the decontamination of a bacterial suspension is presented and discussed. The presented results indicate the promising potential of the exploitation of superhydrophilic coatings in the manufacture of contact surfaces for healthcare units, where the risk of infection spread and contamination by hospital-acquired pathogens is extremely high.

Myrtenol's Effectiveness against Hospital-Acquired Methicillin-Resistant Staphylococcus aureus: Targeting Antibiofilm and Antivirulence Properties.

The emergence of methicillin-resistant Staphylococcus aureus (MRSA) several years ago highlighted the challenge of multidrug-resistant infections, emphasizing the critical need for innovative treatment approaches. Myrtenol, known for its antibacterial and antibiofilm properties, holds promise as a potential treatment option. This study aimed to evaluate the effectiveness of myrtenol against MRSA. The collected MRSA isolates were assessed for antimicrobial susceptibility following the Clinical and Laboratory Standards Institute (CLSI) guidelines 2023. Biofilm formation by MRSA was evaluated using the tissue culture plate (TCP) technique. The minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC), and minimal biofilm inhibitory concentration (MBIC) of myrtenol against MRSA were determined both individually and in combination with antibiotics. Real-time PCR was employed to investigate the impact of myrtenol on the expression of virulence genes (sarA, agrA, and icaD) across the isolates. In this study, MRSA was identified in 90 out of 400 cases (22.5%) of hospital-acquired pathogens. Among the collected MRSA isolates, 53 out of 90 (59%) were found to produce biofilms. The MIC of myrtenol was comparable to the MBC across all tested isolates, they were almost the same. Combinations of myrtenol with most tested antibiotics exhibited synergistic effects exceeding 60%. Among the 53 biofilm-producing isolates, 45 isolates (85%) expressed the sarA gene, 49% expressed the agrA gene, and all biofilm-producing MRSA isolates (100%) expressed the icaD gene. A notable reduction in the relative quantity (RQ) values of virulence gene expression was observed after treatment with the MBIC of myrtenol across all tested isolates. Myrtenol demonstrated strong antimicrobial activity against MRSA, notably reducing the expression of key virulence genes linked to biofilm formation. This suggests its potential as a therapeutic agent for treating biofilm-associated MRSA infections.

Essential gene knockdowns reveal genetic vulnerabilities and antibiotic sensitivities in Acinetobacter baumannii.

The emergence of multidrug-resistant Gram-negative bacteria underscores the need to define genetic vulnerabilities that can be therapeutically exploited. The Gram-negative pathogen, Acinetobacter baumannii, is considered an urgent threat due to its propensity to evade antibiotic treatments. Essential cellular processes are the target of existing antibiotics and a likely source of new vulnerabilities. Although A. baumannii essential genes have been identified by transposon sequencing, they have not been prioritized by sensitivity to knockdown or antibiotics. Here, we take a systems biology approach to comprehensively characterize A. baumannii essential genes using CRISPR interference (CRISPRi). We show that certain essential genes and pathways are acutely sensitive to knockdown, providing a set of vulnerable targets for future therapeutic investigation. Screening our CRISPRi library against last-resort antibiotics uncovered genes and pathways that modulate beta-lactam sensitivity, an unexpected link between NADH dehydrogenase activity and growth inhibition by polymyxins, and anticorrelated phenotypes that may explain synergy between polymyxins and rifamycins. Our study demonstrates the power of systematic genetic approaches to identify vulnerabilities in Gram-negative pathogens and uncovers antibiotic-essential gene interactions that better inform combination therapies.IMPORTANCEAcinetobacter baumannii is a hospital-acquired pathogen that is resistant to many common antibiotic treatments. To combat resistant A. baumannii infections, we need to identify promising therapeutic targets and effective antibiotic combinations. In this study, we comprehensively characterize the genes and pathways that are critical for A. baumannii viability. We show that genes involved in aerobic metabolism are central to A. baumannii physiology and may represent appealing drug targets. We also find antibiotic-gene interactions that may impact the efficacy of carbapenems, rifamycins, and polymyxins, providing a new window into how these antibiotics function in mono- and combination therapies. Our studies offer a useful approach for characterizing interactions between drugs and essential genes in pathogens to inform future therapies.

Pandrug-resistant Acinetobacter baumannii from different clones and regions in Mexico have a similar plasmid carrying the blaOXA-72 gene.

Multidrug-resistant Acinetobacter baumannii is a common hospital-acquired pathogen. The increase in antibiotic resistance is commonly due to the acquisition of mobile genetic elements carrying antibiotic resistance genes. To comprehend this, we analyzed the resistome and virulome of Mexican A. baumannii multidrug-resistant isolates. Six clinical strains of A. baumannii from three Mexican hospitals were sequenced using the Illumina platform, the genomes were assembled with SPAdes and annotated with Prokka. Plasmid SPAdes and MobRecon were used to identify the potential plasmid sequences. Sequence Type (ST) assignation under the MLST Oxford scheme was performed using the PubMLST database. Homologous gene search for known virulent factors was performed using the virulence factor database VFDB and an in silico prediction of the resistome was conducted via the ResFinder databases. The six strains studied belong to different STs and clonal complexes (CC): two strains were ST208 and one was ST369; these two STs belong to the same lineage CC92, which is part of the international clone (IC) 2. Another two strains were ST758 and one was ST1054, both STs belonging to the same lineage CC636, which is within IC5. The resistome analysis of the six strains identified between 7 to 14 antibiotic resistance genes to different families of drugs, including beta-lactams, aminoglycosides, fluoroquinolones and carbapenems. We detected between 1 to 4 plasmids per strain with sizes from 1,800 bp to 111,044 bp. Two strains from hospitals in Mexico City and Guadalajara had a plasmid each of 10,012 bp pAba78r and pAba79f, respectively, which contained the bla OXA-72 gene. The structure of this plasmid showed the same 13 genes in both strains, but 4 of them were inverted in one of the strains. Finally, the six strains contain 49 identical virulence genes related to immune response evasion, quorum-sensing, and secretion systems, among others. Resistance to carbapenems due to pAba78r and pAba79f plasmids in Aba pandrug-resistant strains from different geographic areas of Mexico and different clones was detected. Our results provide further evidence that plasmids are highly relevant for the horizontal transfer of antibiotic resistance genes between different clones of A. baumannii.

Methicillin-Resistant Staphylococcus aureus Colonization in Intensive Care and Burn Units: A Narrative Review.

Methicillin-resistant Staphylococcus aureus (MRSA) is a common hospital-acquired pathogen and can cause a wide spectrum of infections. In recent years, MRSA has emerged as a significant public health concern, particularly in hospitals. Intensive care units (ICUs) and burn units are high-risk areas for hospital-acquired MRSA infections, which can lead to increased morbidity, mortality, and healthcare costs. MRSA exhibits resistance to multiple antibiotics and can cause serious infections, including but not limited to pneumonia, endocarditis, and cutaneous infections, particularly in patients with burn injuries. The prevention and effective management of MRSA infections in both burn patients and those in ICUs is crucial, with strategies like isolation, regular disinfection, and prophylactic intranasal mupirocin. Early diagnosis of MRSA infection and isolation of patients is vital to prevent the spread of MRSA. Implementation of prevention strategies faces many challenges, such as cost, and the most successful infection management practices are still debated. This review has highlighted the substantial concern of MRSA colonization in intensive care and burn units. MRSA poses a significant risk to vulnerable patients, influenced by factors such as compromised immunity and invasive procedures. The prevalence of MRSA colonization varies, influenced by regional factors and infection control practices. Combating MRSA requires a multifaceted approach, including stringent infection control measures and education for healthcare workers and patients. As we move forward, continued research and cooperation are essential to reduce the burden of MRSA in these critical care settings.

Selective Change in the Bacteria Cultured and Isolated in Respiratory Sputum from Elderly Patients during the SARS-CoV-2 Pandemic

The SARS-CoV-2 pandemic has affected social patterns and consequently the prevalence of infections, such as seasonal influenza. It has been reported that invasive pneumococcal infection has markedly decreased worldwide. Method: We retrospectively investigated the bacteria cultured and isolated from 23,052 respiratory sputum samples obtained at our hospital from April 2015 to March 2022. The average patient age was 71.8 years old, with a standard deviation of 16.0 years old. There was no significant difference in the age of the patients or the female-to-male ratio between each year. The detection ratio of bacteria was analyzed in accordance with sputum quality based on the Geckler classification. Results: The detection ratio of community-acquired pneumonia pathogens such as Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae increased in parallel with the quality of the sputum, while that of hospital-acquired pneumonia pathogens such as Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus was not significantly affected by the quality of the sputum. The detection ratio of former pathogens in the good-quality respiratory sputum had decreased significantly since April 2020 by 60–80%, while that of P. aeruginosa and S. aureus had increased by 40–50%. Conclusions: The SARS-CoV-2 pandemic reduced the detection ratio of H. influenzae, M. catarrhalis, and S. pneumoniae but increased that of P. aeruginosa and S. aureus in the good-quality respiratory sputum from elderly patients. The influence of this selective change in isolated bacteria on the health and comorbidity of elderly patients remains to be investigated.

New Insights in Phenothiazinium-Mediated Photodynamic Inactivation of Candida Auris.

In recent years, Candida auris has emerged as a hazardous hospital-acquired pathogen. Its resistance to antifungal treatments makes it challenging, requiring new approaches to manage it effectively. Herein, we aimed to assess the impact of photodynamic inactivation mediated by methylene blue (MB-PDI) or 1,9-dimethyl MB (DMMB-PDI) combined with a red LED against C. auris. To evaluate the photoinactivation of yeasts, we quantified colony-forming units and monitored ROS production. To gain some insights into the differences between MB and DMMB, we assessed lipid peroxidation (LPO) and mitochondrial membrane potential (ΔΨm). After, we verified the effectiveness of DMMB against biofilms by measuring metabolic activity and biomass, and the structures were analyzed through scanning electron microscopy and optical coherence tomography. We also evaluated the cytotoxicity in mammalian cells. DMMB-PDI successfully eradicated C. auris yeasts at 3 μM regardless of the light dose. In contrast, MB (100 μM) killed cells only when exposed to the highest dose of light. DMMB-PDI promoted higher ROS, LPO and ΔΨm levels than those of MB. Furthermore, DMMB-PDI was able to inhibit biofilm formation and destroy mature biofilms, with no observed toxicity in fibroblasts. We conclude that DMMB-PDI holds great potential to combat the global threat posed by C. auris.

Enterococcal Phages: Food and Health Applications.

Enterococcus is a diverse genus of Gram-positive bacteria belonging to the lactic acid bacteria (LAB) group. It is found in many environments, including the human gut and fermented foods. This microbial genus is at a crossroad between its beneficial effects and the concerns regarding its safety. It plays an important role in the production of fermented foods, and some strains have even been proposed as probiotics. However, they have been identified as responsible for the accumulation of toxic compounds-biogenic amines-in foods, and over the last 20 years, they have emerged as important hospital-acquired pathogens through the acquisition of antimicrobial resistance (AMR). In food, there is a need for targeted measures to prevent their growth without disturbing other LAB members that participate in the fermentation process. Furthermore, the increase in AMR has resulted in the need for the development of new therapeutic options to treat AMR enterococcal infections. Bacteriophages have re-emerged in recent years as a precision tool for the control of bacterial populations, including the treatment of AMR microorganism infections, being a promising weapon as new antimicrobials. In this review, we focus on the problems caused by Enterococcus faecium and Enterococcus faecalis in food and health and on the recent advances in the discovery and applications of enterococcus-infecting bacteriophages against these bacteria, with special attention paid to applications against AMR enterococci.

Genomic and Phylogenetic Analysis of a Multidrug-Resistant blaNDM-carrying Klebsiella michiganensis in China.

Klebsiella michiganensis is an emerging hospital-acquired bacterial pathogen. However, there is a dearth of knowledge on the antimicrobial resistance and transmission of K. michiganensis. Here, we characterized the microbiological and genomic features of a carbapenem-resistant K. michiganensis strain harboring the blaNDM-1 gene in China. K. michiganensis strain 2563 was recovered from the sputum sample of a hospitalized patient with pulmonary infection. Whole-genome sequencing of K. michiganensis strain 2563 was conducted using both the short-read Illumina and long-read MinION platforms to thoroughly characterize the genetic context of blaNDM-carrying plasmid in K. michiganensis 2563. Furthermore, BacWGSTdb server was utilized to perform in silico multilocus sequence typing (MLST), identify antimicrobial resistance genes, and conduct genomic epidemiological analyses of the closely related isolates deposited in the public database. K. michiganensis 2563 was resistant to piperacillin, aztreonam, meropenem, imipenem, amoxicillin-clavulanic acid, ampicillin, cefotaxime, cefazolin, ampicillin/sulbactam, cefepime, piperacillin-tazobactam, and ceftazidime. It belonged to sequence type (ST) 43, and the blaNDM-1 gene was found to be located on the plasmid p2563_NDM (54,035 bp). This plasmid showed remarkable similarity to other blaNDM-1-encoding plasmids found in various Enterobacterium species in the public database. The occurrence of global ST43 K. michiganensis was primarily sporadic, and the closest relative of K. michiganensis 2563 was another ST43 isolate 12,084 recovered from China in 2013, which differed by 171 SNPs. Our study reports the genome characteristics of a carbapenem-resistant K. michiganensis strain carrying the blaNDM-1 gene in China, highlighting the need for ongoing surveillance of this pathogen in clinical settings.

Proteogenomic analysis of Serratia marcescens using computational subtractive genomics approach.

Serratia marcescens, a Gram-negative bacterium (Enterobacteriaceae) is a hospital-acquired opportunistic pathogen that infects the urinary and central nervous systems. The identification of new therapeutics against S. marcescens is crucial since it is now multi-drug resistant. Therefore, the current study was aimed to identify potential drug targets against S. marcescens strains i.e. WW4, SM39, and Db11 using comparative metabolic pathway analysis and subtractive genomics approach. The applied bioinformatics-based method was used to identify the unique metabolic pathways as the prioritized drug targets. The downstream analysis has led to the identification of three pathways that are specifically absent and/or present in the specific strain. Consequently, six proteins were identified through subtractive genomic analysis. The identified proteins were found as non-homologous and essential to the pathogen's survival as well as unique to the WW4 strain. The estimated features proposed it as a potential drug target. The selected protein was further subjected to in-depth structural analysis for the structure modeling, structure validation, and protein-protein interaction analysis. Furthermore, the library of ~1500 approved compounds was screened against selected drug target to identify potential drug candidates. The current work may help in repurposing of the drug compounds as novel medication against S. marcescens.