Métodos microbiológicos para la vigilancia del estado de portador de bacterias multirresistentes

Cas-based bacterial detection: recent advances and perspectives

Persistent bacterial infections pose a formidable threat to global health, contributing to widespread challenges in areas such as food safety, medical hygiene, and animal husbandry. Addressing this peril demands the urgent implementation of swift and highly sensitive detection methodologies suitable for point-of-care testing and large-scale screening. These methodologies play a pivotal role in the identification of pathogenic bacteria, discerning drug-resistant strains, and managing and treating diseases. Fortunately, new technology, the CRISPR/Cas system, has emerged. The clustered regularly interspaced short joint repeats (CRISPR) system, which is part of bacterial adaptive immunity, has already played a huge role in the field of gene editing. It has been employed as a diagnostic tool for virus detection, featuring high sensitivity, specificity, and single-nucleotide resolution. When applied to bacterial detection, it also surpasses expectations. In this review, we summarise recent advances in the detection of bacteria such as Mycobacterium tuberculosis (MTB), methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli (E. coli), Salmonella and Acinetobacter baumannii (A. baumannii) using the CRISPR/Cas system. We emphasize the significance and benefits of this methodology, showcasing the capability of diverse effector proteins to swiftly and precisely recognize bacterial pathogens. Furthermore, the CRISPR/Cas system exhibits promise in the identification of antibiotic-resistant strains. Nevertheless, this technology is not without challenges that need to be resolved. For example, CRISPR/Cas systems must overcome natural off-target effects and require high-quality nucleic acid samples to improve sensitivity and specificity. In addition, limited applicability due to the protospacer adjacent motif (PAM) needs to be addressed to increase its versatility. Despite the challenges, we are optimistic about the future of bacterial detection using CRISPR/Cas. We have already highlighted its potential in medical microbiology. As research progresses, this technology will revolutionize the detection of bacterial infections.

Fernández-de-Bobadilla M, Serrano-Tomás MI, Sánchez-Díaz AM, Avendaño-Ortiz J, Coque TM, Ruiz-Garbajosa P, del Campo R, Cantón R. A long-term survey of Serratia spp. bloodstream infections revealed an increase of antimicrobial resistance involving adult population

Serratia spp. is a well-recognized pathogen in neonates; however, limited data are available in adults. We studied microbiological and clinical characteristics of Serratia spp. causing bloodstream infections (BSI) in our institution (January 2005-July 2020). Overall, 141 BSI episodes affecting 139 patients were identified and medical records reviewed. Antimicrobial susceptibility was recovered from our informatics system and 118 isolates from 116 patients were available for further microbiological studies. Whole genome sequencing (WGS) was completed in 107 isolates. Incidence of Serratia BSI was 0.3/1000 overall admissions (range 0.12-0.60), with maximum prevalence (27 episodes, 19.1%) during 2017-2018. Relevant patients' clinical characteristics were 71.9% ≥60 years (n = 100), with high comorbidity rates (49%, ≥2), 23 (74.2%) of them died within 1 month of the BSI episode. WGS identified all isolates as Serratia marcescens when Kraken bioinformatics taxonomic tool was used despite some which were identified as Serratia nematodiphila (32/118) or Serratia ureilytica (5/118) by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Nevertheless, when using MASH distance, Serratia nevei (63/107), S. ureilytica (38/107), and S. marcescens (6/107) were assigned. Carbapenemase (blaVIM-1) and extended-spectrum β-lactases (ESBL) (blaSHV-12) genes were found in seven and three isolates, respectively, one of them expressing both genes. The worldwide-disseminated IncL/M scaffold plasmid was identified in six VIM producers. Four genotypes were established based on their virulence factors and resistome. Serratia spp. emerged as a relevant nosocomial pathogen causing BSI in elderly patients in our hospital, particularly in recent years with a remarkable increase in antibiotic resistance. ESBL and carbapenemases production related to plasmid dissemination are particularly noteworthy.IMPORTANCESerratia spp. is the third most frequent pathogen involved in outbreaks at neonatal facilities and is primarily associated with bacteremia episodes. In this study, we characterized all causing bloodstream infection (BSI) in patients admitted to our hospital during a 16-year period (2005-2020). Despite having no neonatal intensive care unit in our hospital, this study revealed that Serratia spp. is a relevant pathogen causing BSI in elderly patients with high comorbidity rates. A significant increase of antimicrobial resistance was detected over time, particularly in 2020 and coinciding with the coronavirus disease (COVID-19) pandemic and nosocomial spread of multidrug-resistant Serratia spp. isolates. extended-spectrum β-lactases and carbapenemases genes associated with plasmid dissemination, typically detected in other Enterobacterales species, were also identified, reinforcing the role of Serratia spp. in the antimicrobial resistance landscape. Additionally, this work highlights the need to reclassify the species of Serratia, since discrepancies were observed in the identification when using different tools.

Carbapenemase-Producing Bacteria Isolated from ICU Patients of a Peruvian Government Hospital during the COVID-19 Pandemic: A Descriptive Analysis

Background and Objectives: In Peru, the presence of antimicrobial-resistant bacteria is a constant concern in hospitals and has likely increased in frequency during the pandemic. The objective of the study was to analyze the frequency of carbapenemase-producing bacteria resistant to two carbapenems (Imipenem and Meropenem), which were isolated from Peruvian patients in the intensive care unit of the Victor Lazarte Echegaray Hospital in Trujillo (Peru) during the COVID-19 pandemic. Materials and Methods: The biological samples of the patients hospitalized in the ICU were processed in the Microbiology Diagnostic Laboratory of the Víctor Lazarte Echegaray Hospital between May 2021 and March 2022. Antimicrobial sensitivity was determined with the automated system AutoScan-4, and for the identification of the type of carbapenemase, the RESISIT-3 O.K.N K-SET cassettes were used. Results: The results show that 76 cultures (76/129) had resistance to the two carbapenems (imipenem or meropenem), where the most frequent were Klebsiella pneuomoniae (31.6%), Pseudomonas aeruginosa (26.3%), and Acinetobacter baumannii (14.5%). Pseudomonas aeruginosa cultures showed at least three carbapenemase types (KPC, NDM, and OXA-48), while A. baumannii, Escherichia coli, and Burkholderia cepacia complex presented at least two carbapenemases (NDM and OXA-48). The carbapenemase NDM was detected in Enterobacter cloacae, Morganella morganii, and Proteus mirabilis, while KPC was present in all Klebsiella pneumoniae and Klebsiella oxytoca cultures. Conclusions: The samples from patients hospitalized in the Victor Lazarte Echegaray Hospital ICU showed a high prevalence of imipenem- and meropenem-resistant bacteria. These findings are relevant and concerning from the perspective of antibiotic-resistant bacteria monitoring, control, and disinfection. Thus, an appropriate antibiotic policy must be implemented.

Antibiotic Resistance Changes in Gram-Positive Bacteria from Urine Cultures: Development Analysis in a Health Area of South-East Spain

This study analyzed the epidemiology and antibiotic susceptibility profile of significant bacteriuria and assessed the impact of adopting EUCAST criteria on antibiotic resistances. A systematic review was performed on publications in English or Spanish between 1 January 2010 and 30 June 2021 on the susceptibility of Gram-positive bacteria isolated in urinary samples in Europe. A retrospective descriptive study was also conducted on the results of 21,838 urine cultures with presumptive urinary tract infection (UTI) obtained during the past five years by the Department of Microbiology of the Virgen de las Nieves University Hospital (Granada, Spain). The activity of various antibiotics was determined, differentiated among various populations, and interpretations compared according to the application of EUCAST or CLSI criteria. Among 21,838 cases of significant bacteriuria, 27.69% were by Gram-positive bacteria, which were Enterococcus faecalis in 19.04% and Enterococcus faecium in 3.92%. The susceptibility profile remained stable for most antibiotics except for levofloxacin for E. faecalis and Staphylococcus aureus and nitrofurantoin for E. faecium. The resistance of Enterococcus spp. and Staphylococcus spp. to glycopeptides was exceptionally low in our setting. No significant difference in the prevalence of methicillin-resistant Staphylococcus aureus was observed between hospital (26.67%) and community (28.85%) samples. Resistances in our local setting remain stable and appear to be lower than reported in other studies. The adoption of EUCAST vs. CLSI criteria did not produce a general change in resistance rates. Findings suggest the need to revise certain empirical criteria, such as aminoglycoside synergy for Enterococcus and for community-origin S. aureus.

Rectal colonization by resistant bacteria increases the risk of infection by the colonizing strain in critically ill patients with cirrhosis

BACKGROUND & AIMS

It remains unclear whether rectal colonization with multidrug-resistant organisms (MDROs) is prevalent and predisposes to infections by the same pathogens in patients with cirrhosis.

METHODS

Two series of critically ill patients were evaluated. In the Barcelona cohort, 486 consecutive patients were prospectively evaluated, 129 with and 357 without cirrhosis (2015-2016). Rectal swabs were performed at admission and weekly thereafter (until intensive care unit [ICU] discharge) to detect MDRO colonization. Risk factors for colonization and infection by MDROs were evaluated. A retrospective cohort from Frankfurt (421 patients with cirrhosis; 2010-2018) was investigated to evaluate MDRO rectal colonization in another epidemiological scenario.

RESULTS

In the Barcelona cohort, 159 patients were colonized by MDROs (32.7%), 102 (64.2%) at admission and 57 (35.8%) during follow-up. Patients with cirrhosis showed higher rates of rectal colonization at admission than those without cirrhosis (28.7% vs. 18.2%, p = 0.01) but similar colonization rates during ICU stay. Extended-spectrum beta-lactamase-Enterobacterales were the most frequent MDROs isolated in both groups. Colonization by MDROs independently increased the risk of infection by MDROs at admission and during follow-up. Risk of new infection by the colonizing strain was also significantly increased in patients with (hazard ratio [HR] 7.41) and without (HR 5.65) cirrhosis. Rectal colonization by MDROs was also highly prevalent in Frankfurt (n = 198; 47%; 131 at admission [66.2%] and 67 [33.8%] during follow-up), with vancomycin-resistant enterococci being the most frequent colonizing organism. Rectal colonization by MDROs was also associated with an increased risk of infection by MDROs in this cohort. Infections occurring in MDR carriers were mainly caused by the colonizing strain.

CONCLUSION

Rectal colonization by MDROs is extremely frequent in critically ill patients with cirrhosis. Colonization increases the risk of infection by the colonizing resistant strain.

LAY SUMMARY

Rectal colonization by multidrug-resistant organisms (MDROs) is a prevalent problem in patients with cirrhosis requiring critical care. The pattern of colonizing bacteria is heterogeneous with relevant differences between centers. Colonization by MDROs is associated with increased risk of infection by the colonizing bacteria in the short term. This finding suggests that colonization data could be used to guide empirical antibiotic therapy and de-escalation policies in patients with cirrhosis.

Systematic Review of Plasmid AmpC Type Resistances in Escherichia coli and Klebsiella pneumoniae and Preliminary Proposal of a Simplified Screening Method for ampC

Beta-lactamase (BL) production is a major public health problem. Although not the most frequent AmpC type, AmpC-BL is increasingly isolated, especially plasmid AmpC-BL (pAmpC-BL). The objective of this study was to review information published to date on pAmpC-BL in Escherichia coli and Klebsiella pneumoniae, and on the epidemiology and detection methods used by clinical microbiology laboratories, by performing a systematic review using the MEDLINE PubMed database. The predictive capacity of a screening method to detect AmpC-BL using disks with cloxacillin (CLX) was also evaluated by studying 102 Enterobacteriaceae clinical isolates grown in CHROMID ESBL medium with the addition of cefepime (FEP), cefoxitin (FOX), ertapenem (ETP), CLX, and oxacillin with CLX. The review, which included 149 publications, suggests that certain risk factors (prolonged hospitalization and previous use of cephalosporins) are associated with infections by pAmpC-BL-producing microorganisms. The worldwide prevalence has increased over the past 10 years, with a positivity rate ranging between 0.1 and 40%, although AmpC was only detected when sought in a targeted manner. CMY-2 type has been the most prevalent pAmpC-BL-producing microorganism. The most frequently used phenotypic method has been the double-disk synergy test (using CLX disks or phenyl-boronic acid and cefotaxime [CTX] and ceftazidime) and the disk method combined with these inhibitors. In regard to screening methods, a 1-µg oxacillin disk with CLX showed 88.9% sensitivity, 100% specificity, 100% positive predictive value (PPV), 98.9% negative predictive value (NPV), and 98.9% validity index (VI). This predictive capacity is reduced with the addition of extended-spectrum beta-lactamases, showing 62.5% sensitivity, 100% specificity, 100% PPV, 93.5% NPV, and 94.1% VI. In conclusion, there has been a worldwide increase in the number of isolates with pAmpC-BL, especially in Asia, with CMY-2 being the most frequently detected pAmpC-BL-producing type of microorganism. Reduction in its spread requires routine screening with a combination of phenotypic methods (with AmpC inhibitors) and genotypic methods (multiplex PCR). In conclusion, the proposed screening technique is an easy-to-apply and inexpensive test for the detection of AmpC-producing isolates in the routine screening of multidrug-resistant microorganisms.

Schwann Cells Accelerate Osteogenesis via the Mif/CD74/FOXO1 Signaling Pathway In Vitro

Schwann cells have been found to promote osteogenesis by an unclear molecular mechanism. To better understand how Schwann cells accelerate osteogenesis, RNA-Seq and LC-MS/MS were utilized to explore the transcriptomic and metabolic response of MC3T3-E1 to Schwann cells. Osteogenic differentiation was determined by ALP staining. Lentiviruses were constructed to alter the expression of Mif (macrophage migration inhibitory factor) in Schwann cells. Western blot (WB) analysis was employed to detect the protein expression. The results of this study show that Mif is essential for Schwann cells to promote osteogenesis, and its downstream CD74/FOXO1 is also involved in the promotion of Schwann cells on osteogenesis. Further, Schwann cells regulate amino acid metabolism and lipid metabolism in preosteoblasts. These findings unveil the mechanism for Schwann cells to promote osteogenesis where Mif is a key factor.

Prevention, Diagnosis and Management of Post-Surgical Mediastinitis in Adults Consensus Guidelines of the Spanish Society of Cardiovascular Infections (SEICAV), the Spanish Society of Thoracic and Cardiovascular Surgery (SECTCV) and the Biomedical Research Centre Network for Respiratory Diseases (CIBERES)

This is a consensus document of the Spanish Society of Cardiovascular Infections (SEICAV), the Spanish Society of Thoracic and Cardiovascular Surgery (SECTCV) and the Biomedical Research Centre Network for Respiratory Diseases (CIBERES). These three entities have brought together a multidisciplinary group of experts that includes anaesthesiologists, cardiac and cardiothoracic surgeons, clinical microbiologists, infectious diseases and intensive care specialists, internal medicine doctors and radiologists. Despite the clinical and economic consequences of sternal wound infections, to date, there are no specific guidelines for the prevention, diagnosis and management of mediastinitis based on a multidisciplinary consensus. The purpose of the present document is to provide evidence-based guidance on the most effective diagnosis and management of patients who have experienced or are at risk of developing a post-surgical mediastinitis infection in order to optimise patient outcomes and the process of care. The intended users of the document are health care providers who help patients make decisions regarding their treatment, aiming to optimise the benefits and minimise any harm as well as the workload.

Evaluation of desensitization protocols to betalactam antibiotics

WHAT IS KNOWN AND OBJECTIVE

Betalactam antibiotics are the most frequent cause of hypersensitivity reactions. Rapid drug desensitization (RDD) is a technique that induces temporary tolerance to a drug allowing a patient to receive the optimal agent. The increased use of RDD and the lack of standardization among available protocols in terms of formulation, starting dose, number of steps and dosing frequency make it essential to determine the safety and appropriate management of these protocols, especially regarding reconstitution, diluents, stability and drug administration in order to guarantee reproducibility. We reviewed betalactam desensitization protocols in a tertiary hospital, in accordance with currently published practices and evaluated its use on patients over a period of three years.

METHODS

(a) We performed a literature search in PubMed, MEDLINE and Google Scholar databases for case reports and/or systematic reviews describing desensitization protocols for betalactam antibiotics. Pharmacokinetic parameters and physicochemical stability were checked for each antibiotic. (b) We retrospectively reviewed inpatients undergoing our antibiotic desensitization protocols from February 2018 to January 2021. Data and outcomes of desensitization procedures were analysed.

RESULTS

We developed nine RDD protocols: meropenem, ceftriaxone, ceftazidime, ampicillin, ceftolozane/tazobactam, cloxacillin, piperacillin/tazobactam, amoxicillin/clavulanate and penicillin G sodium. Five antibiotics have RDD protocols for two different doses, adjusted to patients with impaired renal function. Detailed data (diluent, total dose, volume, concentrations, duration and stability) of the protocol of each antibiotic used are provided. 28 desensitizations were performed in 17 patients, three of them with confirmed allergies by skin test. 26 out of 28 (92.9%) of them were successfully completed, including those three with positive skin results. The pathogens most frequently involved were E. faecalis and P. aeruginosa; both frequently associated with bacterial resistance. Meropenem, ceftriaxone and ceftazidime were the antibiotics most desensitized. 25 out of 26 (96.1%) procedures were successful in resolving the infection.

WHAT IS NEW AND CONCLUSIONS

Detailed information about compounding, dilution and stability is crucial to ensure safe and successful desensitization processes, as well as good coordination between the Allergy and Pharmacy departments. The increase in bacterial resistance to many of the commercially available antibiotics limits the therapeutic options for treating multidrug-resistant infections; in those situations, antibiotic desensitization may be a key therapeutic option. Although there is a broad consensus in limiting the use of RDD to patients with confirmed allergy, in usual clinical practice its application in those strongly suspected of having type I hypersensitivity is still observed. Our betalactam desensitization protocols have shown themselves to be safe and effective, as evidenced by data from the 17 patients on whom they have been tested.

Management of bacterial and fungal infections in cirrhosis: The MDRO challenge

Bacterial infections are frequent in cirrhotic patients with acute decompensation or acute-on-chronic liver failure and can complicate the clinical course. Delayed diagnosis and inappropriate empirical treatments are associated with poor prognosis and increased mortality. Fungal infections are much less frequent, usually nosocomial and associated with extremely high short-term mortality. Early diagnosis and adequate empirical treatment of infections is therefore key in the management of these patients. In recent decades, antibiotic resistance has become a major worldwide problem in patients with cirrhosis, warranting a more complex approach to antibiotic treatment that includes the use of broad-spectrum antibiotics, new administration strategies, novel drugs and de-escalation policies. Herein, we review epidemiological changes, the main types of multidrug-resistant organisms, mechanisms of resistance, new rapid diagnostic tools and currently available therapeutic options for bacterial and fungal infections in cirrhosis.

Clinical Relevance of Antibiotic Susceptibility Profiles for Screening Gram-negative Microorganisms Resistant to Beta-Lactam Antibiotics

The increasing resistance to antibiotics is compromising the empirical treatment of infections caused by resistant bacteria. Rapid, efficient, and clinically applicable phenotypic methods are needed for their detection. This study examines the phenotypic behavior of β-lactam-resistant Gram-negative bacteria grown on ChromID ESBL medium with ertapenem, cefoxitin, and cefepime disks, reports on the coloration of colonies, and establishes a halo diameter breakpoint for the detection of carbapenemase-producing bacteria. We studied 186 β-lactam-resistant Gram-negative microorganisms (77 with extended spectrum beta lactamase (ESBL), 97 with carbapenemases, and 12 with AmpC β-lactamases (AmpC)). Susceptibility profiles of Gram-negative bacteria that produced ESBL, AmpC, and carbapenemases were similar to the expected profiles, with some differences in the response to cefepime of ESBL-producing microorganisms. Coloration values did not differ from those described by the manufacturer of ChromID ESBL medium. In the screening of carbapenemase production, inhibition halo diameter breakpoints for antibiotic resistance were 18 mm for Enterobacterales and ertapenem, 18 mm for Pseudomonas and cefepime, and 16 mm for Acinetobacter baumannii and cefepime. This innovative phenotypic approach is highly relevant to clinical laboratories, combining susceptibility profiles with detection by coloration of high-priority resistant microorganisms such as carbapenemase-producing A. baumannii, carbapenemase-producing Pseudomonas spp., and ESBL and/or carbapenemase-producing Enterobacterales.

Kpi, a chaperone-usher pili system associated with the worldwide-disseminated high-risk clone Klebsiella pneumoniae ST-15

Control of infections caused by carbapenem-resistant Klebsiella pneumoniae continues to be challenging. The success of this pathogen is favored by its ability to acquire antimicrobial resistance and to spread and persist in both the environment and in humans. The emergence of clinically important clones, such as sequence types 11, 15, 101, and 258, has been reported worldwide. However, the mechanisms promoting the dissemination of such high-risk clones are unknown. Unraveling the factors that play a role in the pathobiology and epidemicity of K. pneumoniae is therefore important for managing infections. To address this issue, we studied a carbapenem-resistant ST-15 K. pneumoniae isolate (Kp3380) that displayed a remarkable adherent phenotype with abundant pilus-like structures. Genome sequencing enabled us to identify a chaperone-usher pili system (Kpi) in Kp3380. Analysis of a large K. pneumoniae population from 32 European countries showed that the Kpi system is associated with the ST-15 clone. Phylogenetic analysis of the operon revealed that Kpi belongs to the little-characterized γ₂-fimbrial clade. We demonstrate that Kpi contributes positively to the ability of K. pneumoniae to form biofilms and adhere to different host tissues. Moreover, the in vivo intestinal colonizing capacity of the Kpi-defective mutant was significantly reduced, as was its ability to infect Galleria mellonella The findings provide information about the pathobiology and epidemicity of Kpi⁺ K. pneumoniae and indicate that the presence of Kpi may explain the success of the ST-15 clone. Disrupting bacterial adherence to the intestinal surface could potentially target gastrointestinal colonization.

Role of surveillance cultures in infection control

Hospital-acquired infections are a known menace to the primary disease, for which a patient is admitted. These infections are twenty times more common in developing countries than in the developed ones. Surveillance for colonised patients can be passive or active process. In many hospitals, active surveillance culture for certain sentinel organisms followed by contact precautions for the same is an important part of infection control policy. Specific measures can be taken on early detection of multidrug-resistant organism, allowing prevention of widespread transmission in hospitals. Cultures are the most conventional and economical microbiological method of detection. The cost of active surveillance is a major challenge, especially for developing nations. These nations lack basic infrastructure and have logistic issues. The guidelines regarding this are not very clearly delineated for developing countries. Each hospital has its own challenges and the process is to be tailor-made accordingly. The following review delineates the various aspects of active surveillance for the colonisation of various organisms and the advantages and disadvantages of the same.

[Ethical aspects of specific precautions programs in patients infected or colonised by multidrug-resistant microorganisms in a hospital setting]

The approach to public health, patient safety and quality of care has led to analysing health situations or problems from a population perspective, in a wide way and giving priority to factors that can normally be left in the background from a clinical point of view. For years, the problem of the use and abuse of antimicrobials, the increase and diffusion of microorganisms resistant to them, cross-transmission, and healthcare related infections have been prioritised both nationally and internationally. To combat these problems, various strategies are being developed and put into practice, from the policies of rational use and optimization of antimicrobials, surveillance, and control of infections related to health care, to training information and awareness strategies. One of the pillars of surveillance and control is the correct application of standard and specific precautions, which within the framework of these comprehensive programs aim to control the transmission of microorganisms of special microbiological and/or epidemiological interest through a series of measures. In hospitals, the application of these precautions (single room, barrier measures, restrictions on access to rooms, waste management…) in patients infected or colonised by these microorganisms can have different repercussions, both for patients and the professionals that attend them, and it is considered pertinent that the protocols and/or programs of specific precautions explicitly include the analysis of the ethical aspects in their preparation, implementation, and monitoring.

High clinical impact of rapid susceptibility testing on CHROMID ESBL® medium directly from swabs

Background

Antibiotic resistance is a serious public health challenge exacerbated by the widespread use of β-lactam and glycopeptide antibiotics. The identification of resistances is crucial, and CHROMID ESBL medium has been developed to detect enterobacteria with extended-spectrum β-lactamases (ESBL). The objective of this study was to evaluate the potential of this medium to detect other types of resistant bacteria.

Methods

Vancomycin, cefoxitin, imipenem, and cefepime disks were used to measure growth on CHROMID ESBL medium of β-lactam-resistant Gram-negative (83 with ESBL, 57 with carbapenemases, 35 with AmpC and 3 Stenotrophomonas maltophilia) and Gram-positive [37 vancomycin-susceptible (vancoS) microorganisms and 21 vancomycin-resistant (vancoR) Enterococcus faecium] clinical isolates (retrospective study) and colonization by the aforementioned bacteria (prospective study), using 649 rectal swabs, 314 pharyngeal swabs, and 44 swabs from other localizations.

Results

Retrospective study: species grown on the medium exhibited different colors. Growth on the medium was observed for: all ESBL enterobacteria, which were susceptible to imipenem and cefoxitin; 95% of isolates with carbapenemases, mostly resistant to imipenem; 80% of those with AmpC; 86% of vancoR E. faecium isolates; and 42% of vancoS E. faecalis isolates, with large growth inhibition halos around the vancomycin disk. Prospective study: vancoR E. faecium, ESBL Klebsiella, Pseudomonas with carbapenemases, A. baumannii (mostly from rectal swabs), S. maltophilia, Achromobacter xylosoxidans, and Burkholderia cenocepacia (mostly from pharyngeal swabs) were isolated from the 246 positive samples.

Conclusions

CHROMID ESBL medium permitted the differential growth of Gram-negative bacteria, many with ESBL and carbapenemases. ESBL enterobacteria were susceptible to imipenem, carbapenemase-producing microorganisms grew around the imipenem disk, and vancoR E. faecium was isolated on the medium. Results of the prospective study demonstrate the potential clinical relevance of this medium. S. maltophilia was more frequently detected with pharyngeal swabs and ESBL Klebsiella, A. baumannii, and Pseudomonas with rectal swabs.

Photoluminescence-tunable fluorescent carbon dots-deposited silver nanoparticle for detection and killing of bacteria

Innovative methods to detect and kill pathogenic bacteria have a pivotal role in the eradication of infectious diseases and the prevention of the growth of antibiotic-resistant bacteria. The combination of fluorescent carbon dots (FCDs) with silver nanoparticles (AgNPs) is an effective material for synergic detection and antimicrobial activity determination. However, the fluorescence quenching of the FCDs owing to an interaction with AgNP is a major limitation. In this study, we designed a system to utilize poly(vinylpyrrolidone) (PVP) and catechol chemistry (PVP@Ag:FCD) in order to avoid the fluorescence quenching of the FCD-AgNP combination due to Forster Resonance Energy Transfer (FRET). PVP@Ag:FCD exhibited bright fluorescence, which can be used for bacterial detection, through the promotion of electrostatic binding with the negatively-charged bacterial surface and generation of fluorescence quenching due to aggregation-induced quenching. Furthermore, the presence of silver nanoparticles in PVP@Ag:FCD produced an excellent bacteria killing efficiency against E. coli and S. aureus, even at low concentrations (0.1 mg/mL). In contaminated river water, the PVP@Ag:FCD system showed a simple, highly sensitive, and effective performance for both the detection and eradication of bacteria. Therefore, this system offers an auspicious method for the future detection and killing of bacteria.

A survey on practices for active surveillance of carriage of multidrug-resistant bacteria in hospitals in the Autonomous Community of Valencia, Spain

A questionnaire-based cross-sectional study was conducted to gather information on current microbiological practices for active surveillance of carriage of multidrug-resistant (MDR) bacteria in hospitals from 14 health departments of the Autonomous Community of Valencia (ACV), Spain, which together provided medical attention to 3,271,077 inhabitants in 2017, approximately 70% of the population of the ACV. The survey consisted of 35 questions on MDR bacteria screening policies, surveillance approach chosen (universal vs. targeted), and microbiological methods and processes in use for routine detection and reporting of colonization by MDR bacteria, including the anatomical sites scheduled to be sampled for each MDR bacterial species, and the methodology employed (culture-based, molecular-based, or both). Our study revealed striking differences across centers, likely attributable to the lack of consensus on optimal protocols for sampling, body sites for screening, and microbiological testing, thus underscoring the need for consensus guidelines on these issues.