Increased mortality associated with meticillin-resistant Staphylococcus aureus (MRSA) infection in the Intensive Care Unit: results from the EPIC II study

Cascade catalysis nanozyme for interfacial functionalization in combating implant infections associated with diabetes via sonodynamic therapy and adaptive immune activation

Innovative solutions are required for the intervention of implant associated infections (IAIs), especially for bone defect patients with chronic inflammatory diseases like diabetes mellitus (DM). The complex immune microenvironment of infections renders implants with direct antibacterial ability inadequate for the prolonged against of bacterial infections. Herein, a synergistic treatment strategy was presented that combined sonodynamic therapy (SDT) with adaptive immune modulation to treat IAIs in diabetes patients. A multifunctional coating was created on the surface of titanium (Ti) implants, consisting of manganese dioxide nanoflakes (MnO2 NFs) with cascade catalytic enzyme activity and a responsive degradable hydrogel containing a sonosensitizer. The reactive oxygen species (ROS) generated by glucose-hydrogen peroxide (H2O2) cascade catalysis and ultrasound (US) activation sonosensitizer helped kill bacteria and release bacterial antigens. Meanwhile, Mn2+ facilitated dendritic cells (DCs) maturation, enhancing antigen presentation to activate both cellular and humoral adaptive immunity against bacterial infections. This approach effectively eliminated bacteria in established diabetic IAIs model and activated systemic antibacterial immunity, providing long-term antibacterial protection. This study presents a non-antibiotic immunotherapeutic strategy for fighting IAIs in chronic diseases.

Sepsis heterogeneity

BACKGROUND

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection, with extremely high mortality. Notably, sepsis is a heterogeneous syndrome characterized by a vast, multidimensional array of clinical and biologic features, which has hindered advances in the therapeutic field beyond the current standards.

DATA SOURCES

We used PubMed to search the subject-related medical literature by searching for the following single and/or combination keywords: sepsis, heterogeneity, personalized treatment, host response, infection, epidemiology, mortality, incidence, age, children, sex, comorbidities, gene susceptibility, infection sites, bacteria, fungi, virus, host response, organ dysfunction and management.

RESULTS

We found that host factors (age, biological sex, comorbidities, and genetics), infection etiology, host response dysregulation and multiple organ dysfunctions can all result in different disease manifestations, progression, and response to treatment, which make it difficult to effectively treat and manage sepsis patients.

CONCLUSIONS

Herein, we have summarized contributing factors to sepsis heterogeneity, including host factors, infection etiology, host response dysregulation, and multiple organ dysfunctions, from the key elements of pathogenesis of sepsis. An in-depth understanding of the factors that contribute to the heterogeneity of sepsis will help clinicians understand the complexity of sepsis and enable researchers to conduct more personalized clinical studies for homogenous patients.

Evaluation of the Antibacterial Effect of Aurone-Derived Triazoles on Staphylococcus aureus

Infections caused by antibiotic-resistant bacteria continue to pose a significant public health threat despite their overall decreasing numbers in the last two decades. One group of compounds fundamental to the search for new agents is low-cost natural products. In this study, we explored a group of newly synthesized novel aurone-derived triazole compounds to identify those with pharmaceutical potential as inhibitors of antibiotic-resistant Staphylococcus aureus. Using the broth microdilution method, antibacterial activities against methicillin-resistant S. aureus ATCC 43300 (MRSA) and methicillin-sensitive S. aureus ATCC 29213 (MSSA) were identified for four aurone-derived triazole compounds, AT106, AT116, AT125, and AT137, using the half-maximal inhibitory concentrations for the bacteria (IC50) and mammalian cell lines (CC50). Compounds AT125 and AT137 were identified to have pharmaceutical potential as the IC50 values against MRSA were 5.412 µM and 3.870 µM, whereas the CC50 values measured on HepG2 cells were 50.57 µM and 39.81 µM, respectively, resulting in selectivity indexes (SI) > 10. Compounds AT106 and AT116 were also selected for further study. IC50 values for these compounds were 5.439 µM and 3.178 µM, and the CC50 values were 60.33 µM and 50.87 µM, respectively; however, SI values > 10 were for MSSA only. Furthermore, none of the selected compounds showed significant hemolytic activity for human erythrocytes. We also tested the four compounds against S. aureus biofilms. Although AT116 and AT125 successfully disrupted MSSA biofilms, there was no measurable potency against MRSA biofilms. Checkerboard antibiotic assays to identify inhibitory mechanisms for these compounds indicated activity against bacterial cell membranes and cell walls, supporting the pharmaceutical potential for aurone-derived triazoles against antibiotic-resistant bacteria. Examining structure-activity relationships between the four compounds in this study and other aurone-derived triazoles in our library suggest that substitution with a halogen on either the salicyl ring or triazole aryl group along with triazoles having nitrile groups improves anti-Staphylococcal activity with the location of the functionality being very important.

Prevalence, antimicrobial susceptibility pattern and multidrug resistance of methicillin-resistant Staphylococcus aureus isolated from clinical samples at a tertiary care teaching hospital: an observational, cross-sectional study from the Himalayan country, Nepal

OBJECTIVE

We sought to determine the prevalence and antimicrobial susceptibility pattern of methicillin-resistant Staphylococcus aureus (MRSA) isolated from the clinical samples at a tertiary care hospital in Nepal.

METHODS

Cross-sectional, observational study design.

STUDY SETTING

The study was carried out at a tertiary care facility, the largest public hospital, Tribhuvan University Teaching Hospital (TUTH), Nepal.

PARTICIPANTS

A total of 7433 clinical samples from hospital inpatients and outpatients available in the TUTH microbiology laboratory were examined. The study included clinical samples from the patients of either sex and across all age groups that had been clinically determined to have S. aureus infections.

RESULTS

Of 7433 clinical samples analysed, S. aureus was recovered from 499 (6.71%). The prevalence of MRSA was discovered to be 26.4% (95% CI 21.6% to 30.4%). The major sources of MRSA were pus, 71 (18.5%). MRSA isolates encountered 100% resistance to penicillin and cloxacillin, followed by ciprofloxacin (80.5%), erythromycin (79.8%), cephalexin (64.9%), cotrimoxazole (61.1%) and clindamycin (58.5%). Chloramphenicol (17.9%), and gentamicin (27.4%), on the other hand, exhibited minimal resistance. None of the isolates were resistant to vancomycin (0.0%). Prevalence of multidrug resistance (MDR) was markedly higher in MRSA, 94.05% (95% CI 89.4% to 98.6%), compared with methicillin-sensitive S. aureus, 52.12% (95% CI 46.2% to 57.8%).

CONCLUSION

Our study indicated a high rate of MRSA and MDR-SA (Multidrug-resistant Staphylococcus aureus) prevalence in a Nepalese tertiary care hospital. Therefore, given the widespread burden of MRSA and the threat of the emergence of resistance to commonly used antibiotics, there is a need for the development, adoption and enforcement of appropriate control policies in these hospital settings. Regular surveillance, reporting mechanism as well as prudent use of antimicrobial agents are crucial to combating the progression of MDR-MRSA prevalence and antibiotic resistance.

The FnBPA from methicillin-resistant Staphylococcus aureus promoted development of oral squamous cell carcinoma

Background

Oral squamous cell carcinoma (OSCC) is the most common tumor in the oral cavity. Methicillin-resistant Staphylococcus aureus (MRSA) were highly detected in OSCC patients; however, the interactions and mechanisms between drug-resistant bacteria (MRSA) and OSCC are not clear.

Aim

The aim of this study was to investigate the promotion of MRSA on the development of OSCC.

Methods

MRSA and MSSA (methicillin-susceptible) strains were employed to investigate the effect on the proliferation of OSCC in vitro and vivo.

Results

All of the MRSA strains significantly increased the proliferation of OSCC cells and MRSA arrested the cell cycles of OSCC cells in the S phase. MRSA activated the expression of TLR-4, NF-κB and c-fos in OSCC cells. MRSA also promoted the development of squamous cell carcinoma in vivo. The virulence factor fnbpA gene was significantly upregulated in all MRSA strains. By neutralizing FnBPA, the promotions of MRSA on OSCC cell proliferation and development of squamous cell carcinoma were significantly decreased. Meanwhile, the activation of c-fos and NF-κB by MRSA was also significantly decreased by FnBPA antibody.

Conclusion

MRSA promoted development of OSCC, and the FnBPA protein was the critical virulence factor. Targeting virulence factors is a new method to block the interaction between a drug-resistant pathogen and development of tumors.

Nanoparticles for Biomedical Application and Their Synthesis

Tremendous developments in nanotechnology have revolutionized the impact of nanoparticles (NPs) in the scientific community and, more recently, in society. Nanomaterials are by their definition materials that have at least one dimension in range of 1 to 100 nm. Nanoparticles are found in many types of different technological and scientific applications and innovations, from delicate electronics to state-of-the-art medical treatments. Medicine has recognized the importance of polymer materials coated with NPs and utilizes them widely thanks to their excellent physical, chemical, antibacterial, antimicrobial, and protective properties. Emphasis is given to their biomedical application, as the nanoscale structures are in the range of many biological molecules. Through this, they can achieve many important features such as targeted drug delivery, imaging, photo thermal therapy, and sensors. Moreover, by manipulating in a "nano-scale" range, their characteristic can be modified in order to obtain the desired properties needed in particular biomedical fields, such as electronic, optical, surface plasmon resonance, and physic-chemical features.

Methicillin-resistant staphylococcus aureus nosocomial infection has a distinct epidemiological position and acts as a marker for overall hospital-acquired infection trends

An ongoing healthcare debate is whether controlling hospital-acquired infection (HAI) from methicillin-resistant Staphylococcus aureus (MRSA) will result in lowering the global HAI rate, or if MRSA will simply be replaced by another pathogen and there will be no change in overall disease burden. With surges in drug-resistant hospital-acquired pathogens during the COVID-19 pandemic, this remains an important issue. Using a dataset of more than 1 million patients in 51 acute care facilities across the USA, and with the aid of a threshold model that models the nonlinearity in outbreaks of diseases, we show that MRSA is additive to the total burden of HAI, with a distinct 'epidemiological position', and does not simply replace other microbes causing HAI. Critically, as MRSA is reduced it is not replaced by another pathogen(s) but rather lowers the overall HAI burden. The analysis also shows that control of MRSA is a benchmark for how well all non-S. aureus nosocomial infections in the same hospital are prevented. Our results are highly relevant to healthcare epidemiologists and policy makers when assessing the impact of MRSA on hospitalized patients. These findings further stress the major importance of MRSA as a unique cause of nosocomial infections, as well as its pivotal role as a biomarker in demonstrating the measured efficacy (or lack thereof) of an organization's Infection Control program.

Nickel Nanoparticles: Applications and Antimicrobial Role against Methicillin-Resistant Staphylococcus aureus Infections

Methicillin-resistant Staphylococcus aureus (MRSA) has evolved vast antibiotic resistance. These strains contain numerous virulence factors facilitating the development of severe infections. Considering the costs, side effects, and time duration needed for the synthesis of novel drugs, seeking efficient alternative approaches for the eradication of drug-resistant bacterial agents seems to be an unmet requirement. Nickel nanoparticles (NiNPs) have been applied as prognostic and therapeutic cheap agents to various aspects of biomedical sciences. Their antibacterial effects are exerted via the disruption of the cell membrane, the deformation of proteins, and the inhibition of DNA replication. NiNPs proper traits include high-level chemical stability and binding affinity, ferromagnetic properties, ecofriendliness, and cost-effectiveness. They have outlined pleomorphic and cubic structures. The combined application of NiNPs with CuO, ZnO, and CdO has enhanced their anti-MRSA effects. The NiNPs at an approximate size of around 50 nm have exerted efficient anti-MRSA effects, particularly at higher concentrations. NiNPs have conferred higher antibacterial effects against MRSA than other nosocomial bacterial pathogens. The application of green synthesis and low-cost materials such as albumin and chitosan enhance the efficacy of NPs for therapeutic purposes.

Cost effectiveness of temporary isolation rooms in acute care settings in Singapore

Objectives

To estimate the change to health service costs and health benefits from a decision to adopt temporary isolation rooms that are effective at isolating the patient within a general ward environment. We assess the cost-effectiveness of a decision to adopt an existing temporary isolation room in a Singapore setting.

Method

We performed a model-based cost-effectiveness analysis to evaluate the impact of a decision to adopt temporary isolation rooms for infection prevention. We estimated changes to the costs from implementation, the number of cases of healthcare associated infection, acute care bed days used, they money value of bed days, the number of deaths, and the expected change to life years. We report the probability that adoption was cost-effective by the cost by life year gained, against a relevant threshold. Uncertainty is addressed with probabilistic sensitivity analysis and the findings are tested with plausible scenarios for the effectiveness of the intervention.

Results

We predict 478 fewer cases of HAI per 100,000 occupied bed days from a decision to adopt temporary isolation rooms. This will result in cost savings of $SGD329,432 and there are 1,754 life years gained. When the effectiveness of the intervention is set at 1% of cases of HAI prevented the incremental cost per life year saved is $16,519; below the threshold chosen for cost-effectiveness in Singapore.

Conclusions

We provide some evidence that adoption of a temporary isolation room is cost-effective for Singapore acute care hospitals. It is plausible that adoption is a positive decision for other countries in the region who may demonstrate fewer resources for infection prevention and control.

Design, synthesis, and biological evaluation of membrane-active honokiol derivatives as potent antibacterial agents

Infections caused by drug-resistant bacteria have emerged to be one of the greatest threats to global public health, and new antimicrobial agents with novel mechanisms of action hence are in an urgent need to combat bacterial resistance. Herein, we reported the design, synthesis, and antibacterial evaluation of novel honokiol derivatives as mimics of antimicrobial peptides (AMPs). These mimics showed potent antimicrobial properties against Gram-positive bacteria. Among them, the most promising compound 13b exhibited excellent antibacterial activity, rapid bactericidal properties, avoidance of antibiotic resistance, and weak hemolytic and cytotoxic activities. In addition, compound 13b not only inhibited the biofilm formation but also destroy the preformed biofilm. Mechanism studies further revealed that compound 13b killed bacteria rapidly by interrupting the bacterial membrane. More intriguingly, compound 13b exhibited potent in vivo antibacterial efficacy in a mouse septicemia model induced by Staphylococcus aureus ATCC43300. These results highlight the potential of 13b to be used as therapeutic agents.

Optimizing Antimicrobial Dosing for Critically Ill Patients with MRSA Infections: A New Paradigm for Improving Efficacy during Continuous Renal Replacement Therapy

The dosage regimen of vancomycin, teicoplanin and daptomycin remains controversial for critically ill patients undergoing continuous renal replacement therapy (CRRT). Monte Carlo simulation was applied to identify the optimal regimens of antimicrobial agents in patients with methicillin-resistant Staphylococcus aureus (MRSA) infections based on the mechanisms of different CRRT modalities on drug clearance. The optimal vancomycin dosage for patients received a CRRT doses ≤ 30 mL/kg/h was 20 mg/kg loading dose followed by 500 mg every 8 h, while 1 g every 12 h was appropriate when 35 mL/kg/h was prescribed. The optimal teicoplanin dosage under a CRRT dose ≤ 25 mL/kg/h was four loading doses of 10 mg/kg every 12 h followed by 10 mg/kg every 48 h, 8 mg/kg every 24 h and 6 mg/kg every 24 h for continuous veno-venous hemofiltration, continuous veno-venous hemodialysis and continuous veno-venous hemodiafiltration, respectively. When the CRRT dose increased to 30–35 mL/kg/h, the teicoplanin dosage should be increased by 30%. The recommended regimen for daptomycin was 6–8 mg/kg every 24 h under a CRRT dose ≤ 25 mL/kg/h, while 8–10 mg/kg every 24 h was optimal under 30–35 mg/kg/h. The CRRT dose has an impact on probability of target attainment and CRRT modality only influences teicoplanin.

Monitoring microbial communities in intensive care units over one year in China

Healthcare-associated infections (HAIs) seriously threaten patient health in intensive care units (ICUs). Profiling the microbial composition and diversity in ICU is important to prevent HAI-related spreading. Given that microbial communities vary across different environments, the time-scale characteristics of pathogens in ICUs have not been explored in China. In our study, to study the bacterial communities of two different ICUs in China, we proceeded dynamic monitoring using 16S rRNA sequencing for a whole year among the bed sheets, bed rails, shared pulse oximeters, bedside lockers, nurses' hands, floor, and carts. Our results showed that the microbial composition significantly changed within months. Significant differences in alpha and beta diversities were also observed among the 12 sampling months in each ICU. Additionally, we found the persistence of several HAI-related bacteria, including Acinetobacter, Pseudomonas, Staphylococcus, Escherichia, and Enterococcus. Source tracking analysis showed that most bacteria in both ICUs came from buildings or human skin. With deep investigations of hospital microbial surveillance on a long-term time-scale, we hope that these results will provide constructive guidelines to prevent the spread of HAIs in ICUs.

Comparative 1-Year Outcomes of Invasive Staphylococcus aureus Infections Among Persons With and Without Drug Use: An Observational Cohort Study

BACKGROUND

Persons who use drugs (PWUD) face substantial risk of Staphylococcus aureus infections. Limited data exist describing clinical and substance use characteristics of PWUD with invasive S. aureus infections or comparing treatment and mortality outcomes in PWUD vs non-PWUD. These are needed to inform optimal care for this marginalized population.

METHODS

We identified adults hospitalized from 2013 to 2018 at 2 medical centers in San Francisco with S. aureus bacteremia or International Classification of Diseases-coded diagnoses of endocarditis, epidural abscess, or vertebral osteomyelitis with compatible culture. In addition to demographic and clinical characteristic comparison, we constructed multivariate Cox proportional hazards models for 1-year infection-related readmission and mortality, adjusted for age, race/ethnicity, housing, comorbidities, and methicillin-resistant S. aureus (MRSA).

RESULTS

Of 963 hospitalizations for S. aureus infections in 946 patients, 372 of 963 (39%) occurred in PWUD. Among PWUD, heroin (198/372 [53%]) and methamphetamine use (185/372 [50%]) were common. Among 214 individuals using opioids, 98 of 214 (46%) did not receive methadone or buprenorphine. PWUD had lower antibiotic completion than non-PWUD (70% vs 87%; P < .001). While drug use was not associated with increased mortality, 1-year readmission for ongoing or recurrent infection was double in PWUD vs non-PWUD (28% vs 14%; adjusted hazard ratio [aHR], 2.0 [95% confidence interval {CI}: 1.3-2.9]). MRSA was independently associated with 1-year readmission for infection (aHR, 1.5 [95% CI: 1.1-2.2]).

CONCLUSIONS

Compared to non-PWUD, PWUD with invasive S. aureus infections had lower rates of antibiotic completion and twice the risk of infection persistence/recurrence at 1 year. Among PWUD, both opioid and stimulant use were common. Models for combined treatment of substance use disorders and infections, particularly MRSA, are needed.

The impact of early target attainment of vancomycin in critically ill patients with confirmed Gram-positive infection: A retrospective cohort study

BACKGROUND

Vancomycin is a commonly used antibiotic in critically ill patients for various indications. Critical illness imposes pharmacokinetic-pharmacodynamics challenges, which makes optimizing vancomycin in this population cumbersome. Data are scarce on the clinical impact of time to therapeutic trough levels of vancomycin in critically ill patients.  This study aims to evaluate the timing to achieve therapeutic trough level of vancomycin on 30-day mortality in critically ill patients.

METHOD

A retrospective cohort study was conducted for all adult critically ill patients with confirmed Gram-positive infection who received IV vancomycin between January 1, 2017, and December 31, 2020. We compared early (< 48 h) versus late (≥ 48 h) attainment of vancomycin therapeutic trough levels. The primary outcome was the 30-day mortality in critically ill patients. Secondary outcomes were the development of resistant organisms, microorganisms eradication within 4-5 days of vancomycin initiation, acute kidney injury (AKI), and length of stay (LOS). Propensity score-matched (1:1 ratio) used based on patient's age, serum creatinine, and albumin values at baseline.

RESULTS

A total of 326 patients were included; 110 patients attained the therapeutic trough levels within 48 h of vancomycin initiation. Late achievement of the therapeutic trough levels was associated with higher 30-day mortality (HR: 2.54; 95% CI [1.24-5.22]; p = 0.01). Additionally, patients who achieved therapeutic trough levels of vancomycin late were more likely to develop AKI (OR = 2.59; 95% CI [1.01-6.65]; p = 0.04). Other outcomes were not statistically significant between the two groups.

CONCLUSION

Early achievement of vancomycin therapeutic levels in patients with confirmed Gram-positive infection was associated with possible survival benefits.

SF5- and SCF3-substituted tetrahydroquinoline compounds as potent bactericidal agents against multidrug-resistant persister Gram-positive bacteria

Bacteria persister cells are immune to most antibiotics and hence compounds that are active against persister bacteria are needed. We screened a chemical library of SF₅- and SCF₃-substituted tetrahydroquinoline compounds, synthesized via the Povarov reaction, for antibacterial activity and identified active compounds that displayed good activities against many Gram-positive bacteria, including persisters. The most potent of these compounds, HSD1835, inhibited the growth of drug-resistant Gram-positive bacterial pathogens (including clinical strains) at concentrations ranging from 1 μg mL^-1 to 4 μg mL^-1. Several of the SCF₃- and SF₅-containing compounds were active against methicillin-resistant Staphylococcus aureus (MRSA) and against the two most fatal strains of vancomycin-resistant Enterococcus (VRE), VRE faecalis and VRE faecium. The compounds showed bactericidal activity against stationary phase persister MRSA in time-kill assays. Mechanistic studies showed that HSD1835 acts by disrupting bacterial membranes. Scanning electron microscopy (SEM) was used to confirm bacterial membrane disruption. Interestingly, in a 30 day serial exposure experiment, MRSA remained susceptible to low-dose HSD1835 whilst resistance to ciprofloxacin and mupirocin emerged by day 10. Analogs of HSD1835, which did not bear the SF₅ or SCF₃ moieties, were inactive against bacteria. Recent reports (G. A. Naclerio, N. S. Abutaleb, K. I. Onyedibe, M. N. Seleem and H. O. Sintim, RSC Med. Chem. 2020, 11, 102-110 and G. A. Naclerio, N. S. Abutaleb, D. Li, M. N. Seleem and H. O. Sintim, J. Med. Chem. 2020, 63(20), 11934-11944) also demonstrated that adding the SF₅ or SCF₃ groups to a different scaffold (oxadiazoles) enhanced the antibacterial properties of the compounds, so it appears that these groups are privileged moieties that enhance the antimicrobial activities of compounds.

Dose Optimization of Vancomycin for Critically Ill Patients Undergoing CVVH: A Prospective Population PK/PD Analysis

The optimal dose of vancomycin in critically ill patients receiving continuous venovenous hemofiltration (CVVH) remains unclear. The objective of this study was to identify factors that significantly affect pharmacokinetic profiles and to further investigate the optimal dosage regimens for critically ill patients undergoing CVVH based on population pharmacokinetics and pharmacodynamic analysis. A prospective population pharmacokinetic analysis was performed at the surgical intensive care unit in a level A tertiary hospital. We included 11 critically ill patients undergoing CVVH and receiving intravenous vancomycin. Serial blood samples were collected from each patient, with a total of 131 vancomycin concentrations analyzed. Nonlinear mixed effects models were developed using NONMEM software. Monte Carlo Simulation was used to optimize vancomycin dosage regimens. A two-compartment model with first-order elimination was sufficient to characterize vancomycin pharmacokinetics for CVVH patients. The population typical vancomycin clearance (CL) was 1.15 L/h and the central volume of distribution was 16.9 L. CL was significantly correlated with ultrafiltration rate (UFR) and albumin level. For patients with normal albumin and UFR between 20 and 35 mL/kg/h, the recommended dosage regimen was 10 mg/kg qd. When UFR was between 35 and 40 mL/kg/h, the recommended dosage regimen was 5 mg/kg q8h. For patients with hypoalbuminemia and UFR between 20 and 25 mL/kg/h, the recommended dosage regimen was 5 mg/kg q8h. When UFR was between 25 and 40 mL/kg/h, the recommended dosage regimen was 10 mg/kg q12h. We recommend clinicians choosing the optimal initial vancomycin dosage regimens for critically ill patients undergoing CVVH based on these two covariates.

Population Pharmacokinetics and Dosing Simulation of Vancomycin Administered by Continuous Injection in Critically Ill Patient

Background: Vancomycin is widely used for empirical antimicrobial therapy in critically ill patients with sepsis. Continuous infusion (CI) may provide more stable exposure than intermittent infusion, but optimal dosing remains challenging. The aims of this study were to perform population pharmacokinetic (PK) analysis of vancomycin administered by CI in intensive care unit (ICU) patients to identify optimal dosages. Methods: Patients who received vancomycin by CI with at least one measured concentration in our center over 16 months were included, including those under continuous renal replacement therapy (CRRT). Population PK was conducted and external validation of the final model was performed in a dataset from another center. Simulations were conducted with the final model to identify the optimal loading and maintenance doses for various stages of estimated creatinine clearance (CRCL) and in patients on CRRT. Target exposure was defined as daily AUC of 400-600 mg·h/L on the second day of therapy (AUC24-48 h). Results: A two-compartment model best described the data. Central volume of distribution was allometrically scaled to ideal body weight (IBW), whereas vancomycin clearance was influenced by CRRT and CRCL. Simulations performed with the final model suggested a loading dose of 27.5 mg/kg of IBW. The maintenance dose ranged from 17.5 to 30 mg/kg of IBW, depending on renal function. Overall, simulation showed that 55.8% (95% CI; 47-64%) of patients would achieve the target AUC with suggested dosages. Discussion: A PK model has been validated for vancomycin administered by CI in ICU patients, including patients under CRRT. Our model-informed precision dosing approach may help for early optimization of vancomycin exposure in such patients.

Generation of truncated derivatives through in silico enzymatic digest of peptide GV30 target MRSA both in vitro and in vivo

•

A novel host-defence peptide GV30 was identified from the frog skin secretion of Hylarana guentheri.

•

Seven short AMPs were generated by in silico enzymatic digest of GV30 using an online proteomic bioinformatic tool PeptideCutter in ExPASy server.

•

Two truncated products, GV23 and GV21, exhibited an improved antibacterial effect against MRSA in vitro and demonstrated a faster bactericidal effect than the parent peptide.

•

GV 21 was found to have a better in vivo anti-MRSA activity and retain the good antibacterial activity under salt and serum conditions, along with lower toxicity.

Methicillin-resistant Staphylococcus aureus (MRSA) causing serious hospital-acquired infections and skin infections has become a “superbug” in clinical treatment. Although the clinical treatment of MRSA is continuously improving, due to its unceasing global spread, MRSA has produced much heated discussion and focused study, therefore suggesting an urgent task to find new antibacterial drugs to combat this issue. Antimicrobial peptides (AMPs) are used as the last-resort drugs for treating multidrug-resistant bacterial infections, but their utilisation is still limited due to their low stability and often strong toxicity.

Here, we evaluated the structure and the bioactivity of an AMP, GV30, derived from the frog skin secretions of Hylarana guentheri, and designed seven truncated derivatives based on the presence of cleavage sites for trypsin using an online proteomic bioinformatic resource PeptideCutter tool. We investigated the anti-MRSA effect, toxicity and salt- and serum-resistance of these peptides. Interestingly, the structure–activity relationship revealed that removing “Rana box” loop could significantly improve the bactericidal speed on MRSA. Among these derivatives, GV21 (GVIFNALKGVAKTVAAQLLKK-NH₂), because of its faster antibacterial effect, lower toxicity, and retains the good antibacterial activity and stability of the parent peptide, is considered to become a new potential antibacterial candidate against MRSA.

Performance of nasal methicillin-resistant Staphylococcus aureus screening for intra-abdominal infections in critically ill adult patients

STUDY OBJECTIVE

Intra-abdominal infections (IAIs) are a common reason for intensive care unit (ICU) admissions, and methicillin-resistant Staphylococcus aureus (MRSA) is an uncommon pathogen in IAIs. Although more data are available in the setting of non-abdominal sources, there are limited data on the performance of nasal MRSA screening for MRSA IAIs. The primary objective of this study was to evaluate the performance of nasal MRSA screening for MRSA IAIs in critically ill adult patients.

DESIGN

This was a multicenter, retrospective, cohort study.

SETTING

A 14-hospital healthcare system between January 1, 2014, and August 31, 2019.

PATIENTS

Adult patients admitted to an ICU for at least 24 h with a diagnosis code for an IAI, a nasal MRSA surveillance screen within 30 days, and an intra-abdominal culture were eligible for inclusion.

INTERVENTION

The primary outcome was to evaluate the performance of nasal MRSA screening for MRSA IAIs by calculating the accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV).

MEASUREMENTS AND MAIN RESULTS

Out of 863 patients randomly screened, a total of 192 patients were included. The study population had a mean age of 60 (SD ±15) years, and 101 (53%) patients were male. Six (3.1%) patients were positive for an MRSA IAI, of which four (66.7%) demonstrated a positive nasal MRSA screen. A total of 186 (96.8%) patients were negative for a MRSA IAI, of which 19 (10.2%) were nasal MRSA-positive and 167 (89.8%) were nasal MRSA-negative. Nasal MRSA screening demonstrated the following performance: accuracy 89.1% (95% CI: 83.8%-93.1%), sensitivity 66.7% (95% CI: 22.3%-95.7%), specificity 89.8% (95% CI: 84.5%-93.7%), PPV 17.4% (95% CI: 9.4%-30.0%), and NPV 98.8% (95% CI: 96.4%-99.6%). There were no significant differences in clinical outcomes, including renal replacement-free days, ICU and hospital length of stay, and in-hospital mortality.

CONCLUSIONS

Among critically ill adult patients with IAIs, a negative nasal MRSA screen within 30 days may help to empirically exclude MRSA as a causative pathogen.

Organometallic ruthenium (η6-p-cymene) complexes interfering with quorum sensing and biofilm formation: an anti-infective approach to combat multidrug-resistance in bacteria

Organometallic ruthenium complexes of flavonoids as antiquorum sensing agents against pathogens likeChromobacterium violaceumATCC 12472,Pseudomonas aeruginosaPAO1 and methicillin-resistantS. aureus(MRSA).

Area under the Curve-Based Dosing of Vancomycin in Critically Ill Patients Using 6-Hour Urine Creatinine Clearance Measurement

BACKGROUND

The area under the curve- (AUC-) guided vancomycin dosing is the best strategy for individualized therapy in critical illnesses. Since AUC can be calculated directly using drug clearance (CLvan), any parameter estimating CLvan will be able to achieve the goal of 24-hour AUC (AUC24 h). The present study was aimed to determine CLvan based on 6-hour urine creatinine clearance measurement in critically ill patients with normal renal function.

METHOD

23 adult critically ill patients with an estimated glomerular filtration rate (eGFR) ≥60 mL/min who received vancomycin infusion were enrolled in this pilot study. Vancomycin pharmacokinetic parameters were determined for each patient using serum concentration data and a one-compartment model provided by MONOLIX software using stochastic approximation expectation-maximization (SAEM) algorithm. Correlation of CLvan with the measured creatinine clearance in 6-hour urine collection (CL6 h) and estimated creatinine clearance by the Cockcroft-Gault formula (CLCG) was investigated.

RESULTS

Data analysis revealed that CL6 h had a stronger correlation with CLvan rather than CLCG (r = 0.823 vs. 0.594; p < 0.001 vs. 0.003). The relationship between CLvan and CL6 h was utilized to develop the following equation for estimating CLvan: CLvan (mL/min) = ─137.4 + CL6 h (mL/min) + 2.5 IBW (kg) (R 2  = 0.826, p < 0.001). Regarding the described model, the following equation can be used to calculate the empirical dose of vancomycin for achieving the therapeutic goals in critically ill patients without renal impairment: total daily dose of vancomycin (mg) = (─137.4CL6-h (mL/min) + 2.5 IBW (kg)) × 0.06 AUC24 h (mg.hr/L).

CONCLUSION

For AUC estimation, CLvan can be obtained by collecting urine in a 6-hour period with good approximation in critically ill patients with normal renal function.

Vancomycin Serum Concentration after 48 h of Administration: A 3-Years Survey in an Intensive Care Unit

The present study assessed the proportion of intensive care unit (ICU) patients who had a vancomycin serum concentration between 20 and 25 mg/L after 24–48 h of intravenous vancomycin administration. From 2016 to 2018, adult ICU patients with vancomycin continuous infusion (CI) for any indication were included. The primary outcome was the proportion of patients with a first-available vancomycin serum concentration between 20–25 mg/L at 24 h (D2) or 48 h (D3). Of 3894 admitted ICU patients, 179 were included. A median loading dose of 15.6 (interquartile range (IQR) = (12.5–20.8) mg/kg) was given in 151/179 patients (84%). The median daily doses of vancomycin infusion for D1 and D2 were 2000 [(IQR (1600–2000)) and 2000 (IQR (2000–2500)) mg/d], respectively. The median duration of treatment was 4 (2–7) days. At D2 or D3, the median value of first serum vancomycin concentration was 19.8 (IQR (16.0–25.1)) with serum vancomycin concentration between 20–25 mg/L reported in 43 patients (24%). Time spent in the ICU before vancomycin initiation was the only risk factor of non-therapeutic concentration at D2 or D3. Acute kidney injury occurred significantly more when vancomycin concentration was supra therapeutic at D2 or D3. At D28, 44 (26%) patients had died. These results emphasize the need of appropriate loading dose and regular monitoring to improve vancomycin efficacy and avoid renal toxicity.

Pathogenic Effect of Prevotella intermedia on a Mouse Pneumonia Model Due to Methicillin-Resistant Staphylococcus aureus With Up-Regulated α-Hemolysin Expression

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a common causative agent of pneumonia; however, the detailed mechanism underlying severe MRSA pneumonia, including association with oral hygiene or periodontitis, remains poorly characterized. In this study, we examined the pathogenic effect of Prevotella intermedia, a major periodontopathic pathogen, on MRSA pneumonia.

Methods: The pathogenic effect of the supernatant of P. intermedia (Pi Sup) was investigated in a murine MRSA pneumonia model, using several clinical strains; whereas the bactericidal activity of polymorphonuclear leukocytes (PMNs) was investigated in vitro. The effect of Pi Sup on messenger RNA (mRNA) expression of the toxin/quorum sensing system (rnaIII) was investigated by quantitative reverse transcription PCR both in vitro and in vivo.

Results: Mice infected by hospital-acquired MRSA (HA-MRSA) with Pi Sup exhibited a significantly lower survival rate, higher bacterial loads in the lungs, and higher α-hemolysin (hla) expression in the lungs, than those without Pi Sup. A similar effect of Pi Sup was not observed with MRSA strains producing Panton-Valentine leucocidin (PVL) or toxic shock syndrome toxin (TSST). In vitro, Pi Sup suppressed bactericidal activity of PMNs against the HA-MRSA strain. HA-MRSA was the clinical strain with the highest ability to proliferate in the lungs and was accompanied by time-dependent up-regulation of rnaIII and hla.

Conclusions: Our results provide novel evidence that the product of P. intermedia exerts a pathogenic effect on MRSA pneumonia, in particular with a strain exhibiting strong proliferation in the lower airway tract. Moreover, our results indicate that P. intermedia affects MRSA toxin expression via quorum sensing in a strain-dependent fashion, which might be important for understanding the pathogenesis of severe MRSA pneumonia.

The Evolving Reduction of Vancomycin and Daptomycin Susceptibility in MRSA-Salvaging the Gold Standards with Combination Therapy

Methicillin-resistant Staphylococcus aureus (MRSA) is associated with substantial morbidity and mortality. Vancomycin (VAN) has been used as the gold standard treatment for invasive MRSA infections for decades but, unfortunately, the reliance of VAN as the primary treatment option against these infections has led to a reduction in VAN susceptibility in MRSA isolates. Although daptomycin (DAP) is another common treatment option against invasive MRSA infections, it has been shown that the development of VAN resistance can lead to DAP nonsusceptibility. VAN or DAP backbone regimens in combination with other antibiotics has been advocated as an alternative approach to improve patient outcomes in VAN/DAP-susceptible infections, enhance outcomes in infections caused by isolates with reduced VAN/DAP susceptibility, and/or prevent the emergence of VAN/DAP resistance or further resistance. A peer-reviewed literature search was conducted using Medline, Google Scholar and PubMed databases. The primary purpose of this review is to describe the mechanisms and epidemiology of MRSA isolates with a reduction in VAN and/or DAP susceptibility, evaluate in vitro and in vivo literature describing combination therapy (CT) against MRSA isolates with reduced VAN and/or DAP susceptibility and describe studies involving the clinical outcomes of patients treated with CT against invasive MRSA infections.

Synergistic effect on anti-methicillin-resistant Staphylococcus aureus among combinations of α-mangostin-rich extract, lawsone methyl ether and ampicillin

α-Mangostin-rich extract (AME) exhibited satisfactory inhibitory activities against all tested MRSA strains, with minimum inhibitory concentrations (MICs) of 7·8-31·25 µg ml^-1 , whereas lawsone methyl ether (LME) and ampicillin revealed weak antibacterial activity with MICs of 62·5-125 µg ml^-1 . However, the combination of AME and LME showed synergistic effects against all tested MRSA strains with fractional inhibitory concentration index (FICI) values of 0·008-0·009, while the combination of AME and ampicillin, as well as LME and ampicillin produced synergistic effects with FICIs of 0·016-0·257. A time-kill assay against MRSA (DMST 20654 strain) revealed a 6-log reduction in CFU per ml, which completely inhibited bacterial growth for the combinations of AME and LME, AME and ampicillin, and LME and ampicillin at a 8-h incubation, while those against MRSA (2468 strain) were at 10-h incubation. The combination of α-mangostin and LME as well as the combinations of each compound with ampicillin synergized the alteration of membrane permeability. In addition, α-mangostin, LME and ampicillin inhibited the biofilm formation of MRSA. These findings indicated that the combinations of AME and LME or each of them in combination with ampicillin had enhanced antibacterial activity against MRSA. Therefore, these compounds might be used as the antibacterial cocktails for treatment of MRSA.

Dynamic contact networks of patients and MRSA spread in hospitals

Methicillin-resistant Staphylococcus aureus (MRSA) is a difficult-to-treat infection. Increasing efforts have been taken to mitigate the epidemics and to avoid potential outbreaks in low endemic settings. Understanding the population dynamics of MRSA is essential to identify the causal mechanisms driving the epidemics and to generalise conclusions to different contexts. Previous studies neglected the temporal structure of contacts between patients and assumed homogeneous behaviour. We developed a high-resolution data-driven contact network model of interactions between 743,182 patients in 485 hospitals during 3,059 days to reproduce the exact contact sequences of the hospital population. Our model captures the exact spatial and temporal human contact behaviour and the dynamics of referrals within and between wards and hospitals at a large scale, revealing highly heterogeneous contact and mobility patterns of individual patients. A simulation exercise of epidemic spread shows that heterogeneous contacts cause the emergence of super-spreader patients, slower than exponential polynomial growth of the prevalence, and fast epidemic spread between wards and hospitals. In our simulated scenarios, screening upon hospital admittance is potentially more effective than reducing infection probability to reduce the final outbreak size. Our findings are useful to understand not only MRSA spread but also other hospital-acquired infections.

Bacterial diversity and functional profile of microbial populations on surfaces in public hospital environments in South Africa: A high throughput metagenomic analysis

With the introduction of the One Health approach to global health advocated by the World Health Organization, the role of the environment as a reservoir and transmission route for diverse microorganisms is increasingly being recognised globally. This study investigated the diversity and functional profiles of bacterial communities using high-throughput metagenomics of the 16S rRNA gene in samples collected from environmental surfaces in different levels of healthcare in South Africa. A total of 150 samples were collected in three public hospitals [District (A), Regional (C) and Central (B)] from intensive care and paediatric wards. Military hospitals were excluded. Swabs were taken from mattresses, drip stands, ward telephones, patient files and sinks. A total of 7,996,346 reads were found, of which 7,319,569 were quality-filtered reads. Unique (and shared) microbial community structures were identified within the different hospital levels, locations and sample source. A total of 11 phyla, 29 classes, 50 orders, 105 families, 190 genera and 288 known species were identified. The primary phyla identified were Proteobacteria, Firmicutes and Actinobacteria. The dominant class identified was Gamma-proteobacteria, followed by Bacilli and Actinobacteria. Acinetobacter (16.08%), Citrobacter (13.64%), Staphylococcus (9.65%) and Corynebacterium (6.15%) were predominant genera. Although the functional profile analysis identified citrate cycle (TCA), signal transduction mechanisms, bisphenol degradation, tyrosine metabolism and transcription-factors as the dominant pathways, human disease functional classes, including involvement in antibiotic resistance, were significantly identified. The drip stands, patient files and ward telephones in all the wards of Hospitals A and C contained a higher number of human diseases functional classes. These findings highlight the potential of different hospital environments to serve as reservoirs and possible sources of bacterial pathogens; thus, the need for better monitoring and hygienic practices within the hospital environment.

Different Types of Coagulase Are Associated With 28-Day Mortality in Patients With Staphylococcus aureus Bloodstream Infections

Background:Staphylococcus aureus (S. aureus), a leading cause of bacteremia and infective endocarditis, exploits the human coagulation system by using a wide range of specific virulence factors. However, the impact of these host-pathogen interactions on the outcome of patients with Staphylococcus aureus bacteremia (SAB) remains unclear.

Methods: A total of 178 patients with S. aureus bacteremia were included and analyzed regarding bacterial factors (coa gene size, vWbp, clfA, clfB, fnbA, fnbB, fib) and clinical parameters. A stepwise multivariate Cox regression model and a Partitioning Around Medoids (PAM) cluster algorithm were used for statistical analysis.

Results: Patients' risk factors for 28-day mortality were creatinine (OR 1.49, p < 0.001), age (OR 1.9, p < 0.002), fibrinogen (OR 0.44, p < 0.004), albumin (OR 0.63, p < 0.02), hemoglobin (OR 0.59, p < 0.03), and CRP (OR 1.72, p < 0.04). Five distinct bacterial clusters with different mortality rates were unveiled, whereof two showed a 2-fold increased mortality and an accumulation of specific coagulase gene sizes, 547-base pairs and 660-base pairs.

Conclusions: Based on the data obtained in the present study an association of coagulase gene size and fib regarding 28-day mortality was observed in patients with S. aureus bloodstream infections. Further animal and prospective clinical studies are needed to confirm our preliminary findings.

Nanoparticles-Based Biosensor Coupled with Multiplex Loop-Mediated Isothermal Amplification for Detection of Staphylococcus aureus and Identification of Methicillin-Resistant S. aureus

Introduction

Staphylococcus aureus (S. aureus), including methicillin-resistant S. aureus (MRSA), is a common human pathogen, which can cause a variety of infections from mild to severe. In this article, a new diagnostic method called multiplex loop-mediated isothermal amplification combined with nanoparticles-based lateral flow biosensor (mLAMP-LFB) has been developed, which was proved to be fast, reliable, and simple for detecting S. aureus, and differentiate MRSA from methicillin-susceptible S. aureus (MSSA).

Materials and Methods

We designed a set of six primers targeting the nuc gene of S. aureus, and a set of five primers targeting the mecA gene of MRSA. The lateral flow biosensor visually reported the S. aureus-LAMP results within 2 mins. S. aureus species and non-S. aureus species were used to identify the specificity and sensitivity of the assay.

Results

The best conditions for LAMP were 50 mins at 63°C, and the sensitivity was 100 fg. No cross-reactivity was shown and the specificity of this assay is 100%. This assay requires 20 mins for DNA preparation, 50 mins for isothermal amplification and 2 mins for biosensor detection. The total time is within 75 mins. Among 96 sputum samples, LAMP-LFB and traditional culture method showed the same results, 8 (8.33%) samples were MRSA-positive, and 9 (9.38%) samples were MSSA-positive. Seven (7.29%) samples were MRSA-positive and 7 (7.29%) were MSSA-positive by PCR method. Compared with the culture method, diagnostic accuracy of m-LAMP-LFB assay was 100%. The results showed that the m-LAMP-LFB method has better detection ability than the PCR method.

Discussion

In short, this m-LAMP-LFB assay is a specific and sensitive method that can quickly identify S. aureus stains, and distinguish MRSA from MSSA, and can be used as a new molecular method for detection of S. aureus in laboratories.

Delay in Antibiotic Administration Is Associated With Mortality Among Septic Shock Patients With Staphylococcus aureus Bacteremia

OBJECTIVES

The relationship between the timing of antibiotics and mortality among septic shock patients has not been examined among patients specifically with Staphylococcus aureus bacteremia.

DESIGN

Retrospective analysis of a Veterans Affairs S. aureus bacteremia database.

SETTING

One-hundred twenty-two hospitals in the Veterans Affairs Health System.

PATIENTS

Patients with septic shock and S. aureus bacteremia admitted directly from the emergency department to the ICU from January 1, 2003, to October 1, 2015, were evaluated.

INTERVENTIONS

Time to appropriate antibiotic administration and 30-day mortality.

MEASUREMENTS AND MAIN RESULTS

A total of 506 patients with S. aureus bacteremia and septic shock were included in the analysis. Thirty-day mortality was 78.1% for the entire cohort and was similar for those participants with methicillin-resistant S. aureus and methicillin-sensitive S. aureus bacteremia. Our multivariate analysis revealed that, as compared with those who received appropriate antibiotics within 1 hour after emergency department presentation, each additional hour that passed before appropriate antibiotics were administered produced an odds ratio of 1.11 (95% CI, 1.02-1.21) of mortality within 30 days. This odds increase equates to an average adjusted mortality increase of 1.3% (95% CI, 0.4-2.2%) for every hour that passes before antibiotics are administered.

CONCLUSIONS

The results of this study further support the importance of prompt appropriate antibiotic administration for patients with septic shock. Physicians should consider acting quickly to administer antibiotics with S. aureus coverage to any patient suspected of having septic shock.

Correlation Between Biofilm Formation and Antibiotic Resistance in MRSA and MSSA Isolated from Clinical Samples in Iran: A Systematic Review and Meta-Analysis

Objectives: This study aimed at reviewing the correlation between biofilm formation and antibiotic resistance in methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) isolates. Materials and Methods: This review followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocols. The literature search was conducted in PubMed, Web of Science (ISI), and Scopus databases. Combinations of Mesh terms such as "biofilms" OR "biofilm formation," AND "Drug Resistance" OR "Antimicrobial Drug Resistance" OR "Antibiotic Resistance" AND "Staphylococcus aureus" OR "Methicillin-resistant Staphylococcus aureus" or "MRSA" AND "Methicillin-sensitive Staphylococcus aureus" OR "MSSA" AND "biofilm-related genes" AND "Prevalence" AND "Iran" were searched. Two reviewers independently searched the databases. Analyses were performed in Comprehensive Meta-Analysis software. The random-effects model was used to obtain the combined prevalence with a 95% confidence interval (CI). Results: The combined prevalence of MRSA retrieved from Iranian clinical samples was 48.3% (95% CI: 40.8-55.9). The pooled rate of biofilm formation in MRSA strains was reported as 80.9% (95% CI: 67.8-89.4). Overall, 52.9%, 45.3%, and 22.5% of MRSA isolates were strong, moderate, and weak biofilm producers, respectively. The highest frequency of biofilm-related genes was observed for icaD gene (67.7%) followed by clfA gene with a frequency of 64.7%. Among seven studies that addressed the relationship between biofilm formation and antibiotic resistance, six reported positive associations. Conclusions: Regarding the MRSA strains, they had a significantly higher ability of biofilm formation than MSSA strains; therefore, preventive measures against infections caused by them are required.

Potential factors contributing to the poor antimicrobial efficacy of SAAP-148 in a rat wound infection model

BACKGROUND

We investigated the efficacy of a synthetic antimicrobial peptide SAAP-148, which was shown to be effective against Methicillin-resistant Staphylococcus aureus (MRSA) on tape-stripped mice skin. Unexpectedly, SAAP-148 was not effective against MRSA in our pilot study using rats with excision wounds. Therefore, we investigated factors that might have contributed to the poor efficacy of SAAP-148. Subsequently, we optimised the protocol and assessed the efficacy of SAAP-148 in an adapted rat study.

METHODS

We incubated 100 µL of SAAP-148 with 1 cm2 of a wound dressing for 1 h and determined the unabsorbed volume of peptide solution. Furthermore, 105 colony forming units (CFU)/mL MRSA were exposed to increasing dosages of SAAP-148 in 50% (v/v) human plasma, eschar- or skin extract or PBS. After 30 min incubation, the number of viable bacteria was determined. Next, ex vivo skin models were inoculated with MRSA for 1 h and exposed to SAAP-148. Finally, excision wounds on the back of rats were inoculated with 107 CFU MRSA overnight and treated with SAAP-148 for 4 h or 24 h. Subsequently, the number of viable bacteria was determined.

RESULTS

Contrary to Cuticell, Parafilm and Tegaderm film, < 20% of peptide solution was recovered after incubation with gauze, Mepilex border and Opsite Post-op. Furthermore, in plasma, eschar- or skin extract > 20-fold higher dosages of SAAP-148 were required to achieve a 2-log reduction (LR) of MRSA versus SAAP-148 in PBS. Exposure of ex vivo models to SAAP-148 for 24 h resulted in a 4-fold lower LR than a 1 h or 4 h exposure period. Additionally, SAAP-148 caused a 1.3-fold lower mean LR at a load of 107 CFU compared to 105 CFU MRSA. Moreover, exposure of ex vivo excision wound models to SAAP-148 resulted in a 1.5-fold lower LR than for tape-stripped skin. Finally, SAAP-148 failed to reduce the bacterial counts in an adapted rat study.

CONCLUSIONS

Several factors, such as absorption of SAAP-148 by wound dressings, components within wound exudates, re-colonisation during the exposure of SAAP-148, and a high bacterial load may contribute to the poor antimicrobial effect of SAAP-148 against MRSA in the rat model.

Cefazolin Versus Anti-Staphylococcal Penicillins for the Treatment of Patients with Methicillin-Susceptible Staphylococcus aureus Infection: A Meta-Analysis with Trial Sequential Analysis

INTRODUCTION

Methicillin-susceptible Staphylococcus aureus (MSSA) is a common cause of infection in humans. Beta-lactam antibiotics are the preferred agents, with anti-staphylococcal penicillins (ASPs) or the first-generation cephalosporin, cefazolin, favored by clinicians. Recent studies comparing the two strategies suggest similar outcomes between the agents. The purpose of this meta-analysis was to explore differences between cefazolin and ASPs for the treatment of MSSA infections.

METHODS

We performed a meta-analysis with trial sequential analysis (TSA) of observational or cohort studies using a random-effects model. Two blinded reviewers independently assessed studies for inclusion, risk of bias, and data extraction. The primary outcome was all-cause mortality. Secondary outcomes included clinical failure, infection recurrence, and antibiotic discontinuation due to adverse events. Subgroup analyses were conducted for the primary outcome by type of ASP, studies with a high percentage of deep-seated infections, and studies of low to moderate risk of bias.

RESULTS

After performing a comprehensive search of the literature, and screening for study inclusion, 19 studies (13,390 patients) were included in the final meta-analysis. Fifteen of the 19 studies (79%) were judged as having a low or moderate risk of bias. Use of cefazolin was associated with lower all-cause mortality [odds ratio (OR) 0.71, 95% confidence interval (CI) 0.56-0.91, p = 0.006, I2 = 28%], clinical failure (OR 0.55, 95% CI 0.41-0.74, p < 0.001, I2 = 0%), and antibiotic discontinuation due to adverse events (OR 0.25, 95% CI 0.16-0.39, p < 0.001, I2 = 23%). Infection recurrence was higher in the cefazolin patients (OR 1.41, 95% CI 1.04-1.93, p = 0.03, I2 = 0%).

CONCLUSION

This meta-analysis demonstrated that the use of cefazolin was associated with significant reductions in all-cause mortality, clinical failure, and discontinuation due to adverse events, but was associated with an increased risk of infection recurrence.

FUNDING

University of Florida Open Access Publishing Fund funded the Rapid Service Fees.

TRIAL REGISTRATION

PROSPERO International Prospective Register of Systematic Reviews (study ID: CRD42018106442).

Unexpected Predictors of Antibiotic Resistance in Housekeeping Genes of Staphylococcus Aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is currently the most commonly identified antibiotic-resistant pathogen in US hospitals. Resistance to methicillin is carried by SCCmec genetic elements. Multilocus sequence typing (MLST) covers internal fragments of seven housekeeping genes of S. aureus. In conjunction with mec typing, MLST has been used to create an international nomenclature for S. aureus. MLST sequence types with a single nucleotide polymorphism (SNP) considered distinct. In this work, relationships among MLST SNPs and methicillin/oxacillin resistance or susceptibility were studied, using a public data base, by means of cross-tabulation tests, multivariable (phylogenetic) logistic regression (LR), decision trees, rule bases, and random forests (RF). Model performances were assessed through multiple cross-validation. Hierarchical clustering of SNPs was also employed to analyze mutational covariation. The number of instances with a known methicillin (oxacillin) antibiogram result was 1526 (649), where 63% (54%) was resistant to methicillin (oxacillin). In univariable analysis, several MLST SNPs were found strongly associated with antibiotic resistance/susceptibility. A RF model predicted correctly the resistance/susceptibility to methicillin and oxacillin in 75% and 63% of cases (cross-validated). Results were similar for LR. Hierarchical clustering of the aforementioned SNPs yielded a high level of covariation both within the same and different genes; this suggests strong genetic linkage between SNPs of housekeeping genes and antibiotic resistant associated genes. This finding provides a basis for rapid identification of antibiotic resistant S. arues lineages using a small number of genomic markers. The number of sites could subsequently be increased moderately to increase the sensitivity and specificity of genotypic tests for resistance that do not rely on the direct detection of the resistance marker itself.

Implications of identifying the recently defined members of the Staphylococcus aureus complex S. argenteus and S. schweitzeri: a position paper of members of the ESCMID Study Group for Staphylococci and Staphylococcal Diseases (ESGS)

BACKGROUND

Staphylococcus argenteus and Staphylococcus schweitzeri, previously known as divergent Staphylococcus aureus clonal lineages, have been recently established as novel, difficult-to-delimit, coagulase-positive species within the S. aureus complex. Methicillin-resistant strains of S. argenteus are known from Australia and the UK. Knowledge of their epidemiology, medical significance and transmission risk is limited and partly contradictory, hampering definitive recommendations. There is mounting evidence that the pathogenicity of S. argenteus is similar to that of 'classical' S. aureus, while as yet no S. schweitzeri infections have been reported.

AIM

To provide decision support on whether and how to distinguish and report both species.

SOURCES

PubMed, searched for S. argenteus and S. schweitzeri.

CONTENT

This position paper reviews the main characteristics of both species and draws conclusions for microbiological diagnostics and surveillance as well as infection prevention and control measures.

IMPLICATIONS

We propose not distinguishing within the S. aureus complex for routine reporting purposes until there is evidence that pathogenicity or clinical outcome differ markedly between the different species. Primarily for research purposes, suitably equipped laboratories are encouraged to differentiate between S. argenteus and S. schweitzeri. Caution is urged if these novel species are explicitly reported. In such cases, a specific comment should be added (i.e. 'member of the S.aureus complex') to prevent confusion with less- or non-pathogenic staphylococci. Prioritizing aspects of patient safety, methicillin-resistant isolates should be handled as recommended for methicillin-resistant Staphylococcus aureus (MRSA). In these cases, the clinician responsible should be directly contacted and informed by the diagnosing microbiological laboratory, as they would be for MRSA. Research is warranted to clarify the epidemiology, clinical impact and implications for infection control of such isolates.

Interventions to improve water supply and quality, sanitation and handwashing facilities in healthcare facilities, and their effect on healthcare-associated infections in low-income and middle-income countries: a systematic review and supplementary scoping review

INTRODUCTION

Healthcare-associated infections (HCAIs) are the most frequent adverse event compromising patient safety globally. Patients in healthcare facilities (HCFs) in low-income and middle-income countries (LMICs) are most at risk. Although water, sanitation and hygiene (WASH) interventions are likely important for the prevention of HCAIs, there have been no systematic reviews to date.

METHODS

As per our prepublished protocol, we systematically searched academic databases, trial registers, WHO databases, grey literature resources and conference abstracts to identify studies assessing the impact of HCF WASH services and practices on HCAIs in LMICs. In parallel, we undertook a supplementary scoping review including less rigorous study designs to develop a conceptual framework for how WASH can impact HCAIs and to identify key literature gaps.

RESULTS

Only three studies were included in the systematic review. All assessed hygiene interventions and included: a cluster-randomised controlled trial, a cohort study, and a matched case-control study. All reported a reduction in HCAIs, but all were considered at medium-high risk of bias. The additional 27 before-after studies included in our scoping review all focused on hygiene interventions, none assessed improvements to water quantity, quality or sanitation facilities. 26 of the studies reported a reduction in at least one HCAI. Our scoping review identified multiple mechanisms by which WASH can influence HCAI and highlighted a number of important research gaps.

CONCLUSIONS

Although there is a dearth of evidence for the effect of WASH in HCFs, the studies of hygiene interventions were consistently protective against HCAIs in LMICs. Additional and higher quality research is urgently needed to fill this gap to understand how WASH services in HCFs can support broader efforts to reduce HCAIs in LMICs.

PROSPERO REGISTRATION NUMBER

CRD42017080943.

Correlation between the use of antibiotics and development of a resistant bacterial infection in patients in the ICU

The current study analyzed the correlation between the use of antibiotics and development of a resistant bacterial infection in 454 patients in intensive care units (ICUs), and this study also examined factors related to development of an infection in order to facilitate more rational use of antibiotics and to reduce the incidence of resistant bacterial infections. Potential subjects were patients who were admitted to the ICU in 2016, and 454 such patients were selected using cluster sampling. Patient information was documented using an original questionnaire, Patients in the ICU with a Resistant Bacterial Infection. The correlation between use of an antibiotic and development of a resistant bacterial infection was examined. The rate of infection significantly increased over time and with receipt of various antibiotics. The development of a resistant bacterial infection was found to correlate with the use of antibiotics. Antibiotics should be used more carefully to reduce the incidence of resistant bacterial infections.

An ultra-performance liquid chromatography–tandem mass spectrometry method to quantify vancomycin in human serum by minimizing the degradation product and matrix interference

Aim: This study aimed to develop and validate a method for better therapeutic monitoring of vancomycin serum concentration. Methods & results: An ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method was developed and validated to minimize the interference of crystalline degradation product and matrix. It was compared with chemiluminescence microparticle immunoassay (CMIA) and ultra-performance liquid chromatography with ultraviolet detection (UPLC-UV) in the performance of testing normal, on-dialysis and hemolytic serum samples. For on-dialysis samples, a moderate correlation (r = 0.534) was observed between UPLC-UV and UPLC–MS/MS. In testing hemolytic samples, ten (10/85, 11.8%) samples were overestimated by CMIA method. Conclusion: Vancomycin concentration determined by CMIA, UPLC-UV was more affected by various panels of serum samples than UPLC–MS/MS assay, suggesting that UPLC–MS/MS is a more reliable and promising tool for clinical vancomycin therapeutic drug monitoring.

Phenolic Compounds from Humulus lupulus as Natural Antimicrobial Products: New Weapons in the Fight against Methicillin Resistant Staphylococcus aureus, Leishmania mexicana and Trypanosoma brucei Strains

New anti-infective agents are urgently needed to fight microbial resistance. Methicillin-resistant Staphylococcus aureus (MRSA) strains are particularly responsible for complicated pathologies that are difficult to treat due to their virulence and the formation of persistent biofilms forming a complex protecting shell. Parasitic infections caused by Trypanosoma brucei and Leishmania mexicana are also of global concern, because of the mortality due to the low number of safe and effective treatments. Female inflorescences of hop produce specialized metabolites known for their antimicrobial effects but underexploited to fight against drug-resistant microorganisms. In this study, we assessed the antimicrobial potential of phenolic compounds against MRSA clinical isolates, T. brucei and L. mexicana. By fractionation process, we purified the major prenylated chalcones and acylphloroglucinols, which were quantified by UHPLC-UV in different plant parts, showing their higher content in the active flowers extract. Their potent antibacterial action (MIC < 1 µg/mL for the most active compound) was demonstrated against MRSA strains, through kill curves, post-antibiotic effects, anti-biofilm assays and synergy studies with antibiotics. An antiparasitic activity was also shown for some purified compounds, particularly on T. brucei (IC₅₀ < 1 to 11 µg/mL). Their cytotoxic activity was assessed both on cancer and non-cancer human cell lines.

Synthesis of novel dihydrotriazine derivatives bearing 1,3-diaryl pyrazole moieties as potential antibacterial agents

Three novel series of dihydrotriazine derivatives bearing 1,3-diaryl pyrazole moieties were designed, synthesized and evaluated in terms of their antibacterial and antifungal activities. Most of the synthesized compounds showed potent inhibition of several Gram-positive bacterial strains (including multidrug-resistant clinical isolates) and Gram-negative bacterial strains with minimum inhibitory concentration values in the range of 1-64 µg/mL. Compounds 4b and 4c presented the most potent inhibitory activity against Gram-positive bacteria (S. aureus 4220, MRSA 3167, QRSA 3519) and Gram-negative bacteria (E. coli 1924), with minimum inhibitory concentration values of 1 or 2 µg/mL. Compared with previous studies, these compounds exhibited a broad spectrum of inhibitory activity. The cytotoxic activity of the compounds 4a, 4b, 4c and 11n were assessed in L02 cells. In vitro enzyme study implied that compound 4c exerted its antibacterial activity through DHFR inhibition.

Low-toxicity amphiphilic molecules linked by an aromatic nucleus show broad-spectrum antibacterial activity and low drug resistance

Amphiphilic molecules linked by an aromatic nucleus, possessing strong bactericidal activity, high selectivity, less drug resistance, and high in vivo efficacy against MRSA, were developed.

Is methicillin-resistant Staphylococcus Aureus infection associated with higher mortality and morbidity in hospitalized patients? A cohort study of 551 patients from South Western India

Purpose

To determine morbidity and mortality of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) infections in a tertiary health care facility.

Methods

A cohort study among hospitalized adult patients with culture proven MRSA or MSSA monoinfection were recruited in a tertiary referral center in South India from November 2011 to December 2012.

Results

Of total 551 subjects, 284 (52%) had MRSA and 267 (48%) MSSA infection. A total of 184 (65%) subjects had health care-associated MRSA (HA-MRSA) and 100 (35%) community-associated MRSA (CA-MRSA). Chronic kidney disease and recent antibiotic use had significant association with MRSA. MRSA patients had significant respiratory infection (OR 2.24 [1.04, 5.16]) and bacteremia (OR 2.24 [10.40, 5.16]), relative to MSSA. MSSA group had better survival function compared to MRSA group (P=0.028). Median duration of ICU stays were 5 days (IQR 4, 8) and 2 days (IQR 2, 2) in MRSA and MSSA, respectively. Complications such as acute kidney injury, sepsis, multiorgan dysfunction, need for supportive measures were more in the MRSA group.

Conclusion

MRSA imposes a huge burden in Indian scenario and HA-MRSA remains the main culprit. Patients with history of chronic kidney disease and recent use of antibiotics were found to be at a higher risk. Patients with MRSA infections tend to have poorer outcomes in terms of longer hospital stay, greater complications, and mortality.

Relationship Between Initial Vancomycin Trough Levels and Early-Onset Vancomycin-Associated Nephrotoxicity in Critically Ill Patients

BACKGROUND

Appropriate initial dosing of vancomycin (VCM) is important in improving survival and in preventing nephrotoxicity in critically ill patients, but the potential relationship between initial VCM trough levels and early-onset nephrotoxicity remains unclear. We examined the relationship between initial VCM trough levels and early-onset VCM-associated nephrotoxicity.

METHODS

We performed a retrospective study of patients who had therapeutic drug monitoring of VCM with initial trough levels within 4 days after the beginning of VCM administration. We excluded patients who received renal replacement therapy from 2 days before to 7 days after the beginning of VCM administration, were younger than 18 years, or had renal dysfunction before the beginning of VCM administration. Early-onset VCM-associated nephrotoxicity was defined as an increase in serum creatinine level of ≥0.5 mg/dL (44.2 μmol/L) or 50% above baseline for 2 or more consecutive days within 7 days after the beginning of VCM administration.

RESULTS

Among 109 enrolled patients, 13 patients had early-onset VCM-associated nephrotoxicity. Its incidence rate was 31.3% in patients with initial trough levels of ≥20g/mL, which was significantly higher than 6.3% in patients with initial trough levels of <10 mg/L. Multiple logistic regression analysis demonstrated that early-onset VCM-associated nephrotoxicity was associated with initial trough levels of ≥20 mg/L (odds ratio, 5.0; 95% confidence interval, 1.3-19.1) and with vasopressor use (odds ratio, 5.0; 95% confidence interval, 1.3-19.1). Kaplan-Meier analysis showed that the probability of nonnephrotoxicity for patients with initial VCM trough levels of ≥20 mg/L was lower compared with patients with trough levels of <15 mg/L.

CONCLUSIONS

Initial trough levels of ≥20 mg/L but not ≥15 mg/L were associated with early-onset VCM-associated nephrotoxicity in critically ill patients. Future prospective studies are needed to examine outcomes in critically ill patients achieving initial VCM trough levels of 15-20 mg/L.