Increasing resistance to vancomycin and other glycopeptides in Staphylococcus aureus

Nanoarchitectonics of in Situ Antibiotic-Releasing Acicular Nanozymes for Targeting and Inducing Cuproptosis-like Death to Eliminate Drug-Resistant Bacteria

A series of progress has been made in the field of antimicrobial use of nanozymes due to their superior stability and decreased susceptibility to drug resistance. However, catalytically generated reactive oxygen species (ROS) are insufficient for coping with multidrug-resistant organisms (MDROs) in complex wound environments due to their low targeting ability and insufficient catalytic activity. To address this problem, chemically stable copper-gallic acid-vancomycin (CuGA-VAN) nanoneedles were successfully constructed by a simple approach for targeting bacteria; these nanoneedles exhibit OXD-like and GSH-px-like dual enzyme activities to produce ROS and induce bacterial cuproptosis-like death, thereby eliminating MDRO infections. The results of in vitro experiments showed that the free carboxylic acid of GA could react with the free ammonia of teichoic acid in the methicillin-resistant Staphylococcus aureus (MRSA) cell wall skeleton. Thus, CuGA-VAN nanoneedles can rapidly "capture" MRSA in liquid environments, releasing ROS, VAN and Cu2+ on bacterial surfaces to break down the MRSA barrier, destroying the biofilm. In addition, CuGA-VAN effectively promoted wound repair cell proliferation and angiogenesis to facilitate wound healing while ensuring biosafety. According to transcriptome sequencing, highly internalized Cu2+ causes copper overload toxicity; downregulates genes related to the bacterial glyoxylate cycle, tricarboxylic acid cycle, and oxidative respiratory chain; and induces lipid peroxidation in the cytoplasm, leading to bacterial cuproptosis-like death. In this study, CuGA-VAN was cleverly designed to trigger a cascade reaction of targeting, drug release, ROS-catalyzed antibacterial activity and cuproptosis-like death. This provides an innovative idea for multidrug-resistant infections.

Global distribution of heterogeneous vancomycin-intermediate Staphylococcus aureus strains (1997-2021): a systematic review and meta-analysis

BACKGROUND

Heterogeneous vancomycin-intermediate Staphylococcus aureus is considered one of the main causes in treatment failure of vancomycin, which leads to poor clinical outcomes. Herein, we comprehensively evaluated characteristics such as global prevalence, trend, and genetic backgrounds of these strains.

METHODS

In this study, we conducted a meta-analysis based on PRISMA checklist 2020. In the beginning, global databases were searched to achieve the studies related to the prevalence of hVISA in clinical isolates of methicillin-resistant Staphylococcus aureus. After retrieving the eligible English studies, the prevalence of hVISA isolates and their trend changes were assessed using event rate with 95% confidence intervals.

RESULTS

In the present study, the prevalence of 114 801 MRSA isolates (of 124 studies) was 64%. According to our results, although the frequency of infection with hVISA is increasing in recent years, there is not a significant difference between Asian countries and Europe/America (6.1% vs. 6.8%). In addition, infection with hVISA bacteria was higher in bacteraemic patients than other infections (9.4% vs. 5.5%), which increases hospitalization, treatment costs, and mortality in these patients. Isolates harbouring SCCmec types II and III are most common genotypes in hVISA strains.

CONCLUSIONS

The prevalence of hVISA is increasing, which will reduce the effectiveness of vancomycin treatment in the coming years. The presence of hVISA stains in blood samples was higher than the other samples, which is threatening for bacteraemic patients. The results of the current study indicate a universal program to identify and control the spread of such strains in nosocomial infections.

Monitoring of antimicrobial resistance in respiratory tract pathogens during the COVID-19 pandemic: A retrospective study

To understand the distribution and antimicrobial resistance (AMR) of pathogens in respiratory samples in Changle District People's Hospital in Fujian Province in recent years, and provide empirical guidance for infection control and clinical treatment in the region. A retrospective analysis was conducted on 5137 isolates of pathogens from respiratory samples collected from 2019 to 2022. The AMR patterns were systematically analyzed. For research purposes, the data was accessed on October 12, 2023. A total of 3517 isolates were included in the study, including 811 (23.06%) gram-positive bacteria and 2706 (76.94%) gram-negative bacteria. The top 3 gram-positive bacteria were Staphylococcus aureus with 455 isolates (12.94%), Streptococcus pneumoniae with 99 isolates (2.81%), and Staphylococcus hemolytic with 99 isolates (2.81%). The top 3 gram-negative bacteria were Klebsiella pneumoniae with 815 isolates (23.17%), Pseudomonas aeruginosa with 589 isolates (16.75%), and Acinetobacter baumannii with 328 isolates (9.33%). The proportion of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and K pneumoniae fluctuated between 41.9% and 70.5%, and 18.6% and 20.9%, respectively. The resistance rates of E coli, K pneumoniae, P aeruginosa, and A baumannii to carbapenems were 2.36%, 8.9%, 18.5%, and 19.6%, respectively. The prevalence of methicillin-resistant S aureus (MRSA) was 48.55%, but it decreased to 38.4% by 2022. The resistance rate of Staphylococcus haemolyticus to methicillin was 100%, and 1 case of vancomycin-resistant strain was detected. K pneumoniae, P aeruginosa, A baumannii, and S aureus are the main pathogens in respiratory samples. Although the resistance rates of some multidrug-resistant strains have decreased, ESBL-producing Enterobacteriaceae, carbapenem-resistant bacteria have still increased. Therefore, it is necessary to strengthen the monitoring of pathogen resistance, promote rational use of antibiotics, and promptly report findings.

Use of Biomaterials in 3D Printing as a Solution to Microbial Infections in Arthroplasty and Osseous Reconstruction

The incidence of microbial infections in orthopedic prosthetic surgeries is a perennial problem that increases morbidity and mortality, representing one of the major complications of such medical interventions. The emergence of novel technologies, especially 3D printing, represents a promising avenue of development for reducing the risk of such eventualities. There are already a host of biomaterials, suitable for 3D printing, that are being tested for antimicrobial properties when they are coated with bioactive compounds, such as antibiotics, or combined with hydrogels with antimicrobial and antioxidant properties, such as chitosan and metal nanoparticles, among others. The materials discussed in the context of this paper comprise beta-tricalcium phosphate (β-TCP), biphasic calcium phosphate (BCP), hydroxyapatite, lithium disilicate glass, polyetheretherketone (PEEK), poly(propylene fumarate) (PPF), poly(trimethylene carbonate) (PTMC), and zirconia. While the recent research results are promising, further development is required to address the increasing antibiotic resistance exhibited by several common pathogens, the potential for fungal infections, and the potential toxicity of some metal nanoparticles. Other solutions, like the incorporation of phytochemicals, should also be explored. Incorporating artificial intelligence (AI) in the development of certain orthopedic implants and the potential use of AI against bacterial infections might represent viable solutions to these problems. Finally, there are some legal considerations associated with the use of biomaterials and the widespread use of 3D printing, which must be taken into account.

Treatment of MRSA Infection: Where are We?

Staphylococcus aureus is a leading cause of septicemia, endocarditis, pneumonia, skin and soft tissue infections, bone and joint infections, and hospital-acquired infections. In particular, methicillin-resistant Staphylococcus aureus (MRSA) is associated with high morbidity and mortality, and continues to be a major public health problem. The emergence of multidrug-resistant MRSA strains along with the wide consumption of antibiotics has made anti-MRSA treatment a huge challenge. Novel treatment strategies (e.g., novel antimicrobials and new administrations) against MRSA are urgently needed. In the past decade, pharmaceutical companies have invested more in the research and development (R&D) of new antimicrobials and strategies, spurred by favorable policies. All research articles were collected from authentic online databases, including Google Scholar, PubMed, Scopus, and Web of Science, by using different combinations of keywords, including 'anti-MRSA', 'antibiotic', 'antimicrobial', 'clinical trial', 'clinical phase', clinical studies', and 'pipeline'. The information extracted from articles was compared to information provided on the drug manufacturer's website and Clinical Trials.gov (https://clinicaltrials.gov/) to confirm the latest development phase of anti-MRSA agents. The present review focuses on the current development status of new anti-MRSA strategies concerning chemistry, pharmacological target(s), indications, route of administration, efficacy and safety, pharmacokinetics, and pharmacodynamics, and aims to discuss the challenges and opportunities in developing drugs for anti-MRSA infections.

Antibiotic adjuvants: synergistic tool to combat multi-drug resistant pathogens

The rise of multi-drug resistant (MDR) pathogens poses a significant challenge to the field of infectious disease treatment. To overcome this problem, novel strategies are being explored to enhance the effectiveness of antibiotics. Antibiotic adjuvants have emerged as a promising approach to combat MDR pathogens by acting synergistically with antibiotics. This review focuses on the role of antibiotic adjuvants as a synergistic tool in the fight against MDR pathogens. Adjuvants refer to compounds or agents that enhance the activity of antibiotics, either by potentiating their effects or by targeting the mechanisms of antibiotic resistance. The utilization of antibiotic adjuvants offers several advantages. Firstly, they can restore the effectiveness of existing antibiotics against resistant strains. Adjuvants can inhibit the mechanisms that confer resistance, making the pathogens susceptible to the action of antibiotics. Secondly, adjuvants can enhance the activity of antibiotics by improving their penetration into bacterial cells, increasing their stability, or inhibiting efflux pumps that expel antibiotics from bacterial cells. Various types of antibiotic adjuvants have been investigated, including efflux pump inhibitors, resistance-modifying agents, and compounds that disrupt bacterial biofilms. These adjuvants can act synergistically with antibiotics, resulting in increased antibacterial activity and overcoming resistance mechanisms. In conclusion, antibiotic adjuvants have the potential to revolutionize the treatment of MDR pathogens. By enhancing the efficacy of antibiotics, adjuvants offer a promising strategy to combat the growing threat of antibiotic resistance. Further research and development in this field are crucial to harness the full potential of antibiotic adjuvants and bring them closer to clinical application.

Low utilization of vancomycin in febrile neutropenia: real-world evidence from 4 Brazilian centers

PURPOSE

The prompt initiation of a betalactam antibiotic in febrile neutropenic patients is considered standard of care, while the empiric use of vancomycin is recommended by guidelines in specific situations, with a low level of evidence. The objective of this study was to assess the utilization of vancomycin in the management of febrile neutropenia within four Brazilian medical centers that implemented more stringent criteria for its administration.

METHODS

A comprehensive retrospective analysis was performed encompassing all instances of febrile neutropenia observed during the period from 2013 to 2019. The primary focus was to identify the reasons for initiating vancomycin therapy.

RESULTS

A total of 536 consecutive episodes of febrile neutropenia were documented, involving 384 patients with a median age of 52 years (range 18-86). Chemotherapy preceded febrile neutropenia in 59.7% of cases, while 40.3% occurred after hematopoietic stem cell transplantation. The most prevalent underlying diseases were acute myeloid leukemia (26.5%) and non-Hodgkin's lymphoma (22%). According to international guidelines, vancomycin should have been initiated at the onset of fever in 145 episodes (27%); however, it was administered in only 27 cases (5.0%). Three episodes were associated with Staphylococcus aureus bacteremia, two of which were methicillin resistant. The 15-day and 30-day mortality rates were 5.0% and 9.9%, respectively.

CONCLUSIONS

The results of this study underscore the notably low utilization rate of vancomycin in cases of febrile neutropenia, despite clear indications outlined in established guidelines. These findings emphasize the importance of carefully implementing guideline recommendations, considering local epidemiological factors, especially when the strength of recommendation is weak.

The prevalence of vancomycin-resistant Staphylococcus aureus in Ethiopia: a systematic review and meta-analysis

INTRODUCTION

Vancomycin-resistant Staphylococcus aureus, identified as a "high priority antibiotic-resistant pathogen" by the World Health Organization, poses a significant threat to human health. This systematic review and meta-analysis aimed to estimate the pooled prevalence of vancomycin-resistant Staphylococcus aureus in Ethiopia.

METHODS

This systematic review and meta-analysis was reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies that reported VRSA prevalence due to infection or carriage from human clinical specimens were extensively searched in bibliographic databases and grey literatures using entry terms and combination key words. Electronic databases like PubMed, Google Scholar, Wiley Online Library, African Journal Online, Scopus, Science Direct, Embase, and ResearchGate were used to find relevant articles. In addition, the Joanna Briggs Institute quality appraisal tool was used to assess the quality of the included studies. Stata version 14 software was used for statistical analysis. Forest plots using the random-effect model were used to compute the overall pooled prevalence of VRSA and for the subgroup analysis. Heterogeneity was assessed using Cochrane chi-square (I2) statistics. After publication bias was assessed using a funnel plot and Egger's test, trim & fill analysis was carried out. Furthermore, sensitivity analysis was done to assess the impact of a single study on pooled effect size.

RESULTS

Of the 735 studies identified, 31 studies that fulfilled the eligibility criteria were included for meta-analysis consisted of 14,966 study participants and 2,348 S. aureus isolates. The overall pooled prevalence of VRSA was 14.52% (95% CI: 11.59, 17.44). Significantly high level of heterogeneity was observed among studies (I2 = 93.0%, p < 0.001). The region-based subgroup analysis depicted highest pooled prevalence of 47.74% (95% CI: 17.79, 77.69) in Sidama region, followed by 14.82% (95% CI: 8.68, 19.88) in Amhara region, while Oromia region had the least pooled prevalence 8.07% (95% CI: 4.09, 12.06). The subgroup analysis based on AST methods depicted a significant variation in pooled prevalence of VRSA (6.3% (95% CI: 3.14, 9.43) for MIC-based methods, and 18.4% (95% CI: 14.03, 22.79) for disk diffusion AST method) which clearly showed that disk diffusion AST method overestimates the pooled VRSA prevalence. The total number of S. aureus isolates was found to be the responsible variable for the existence of heterogeneity among studies (p = 0.033).

CONCLUSION

This study showed an alarmingly high pooled prevalence of VRSA necessitating routine screening, appropriate antibiotic usage, and robust infection prevention measures to manage MRSA infections and control the emergence of drug resistance. Furthermore, mainly attributable to the overestimation of VRSA burden while using disk diffusion method, there is an urgent need to improve the methods to determine vancomycin resistance in Ethiopia and incorporate MIC-based VRSA detection methods in routine clinical laboratory tests, and efforts should be directed at improving it nationally.

TRIAL REGISTRATION

PROSPERO registration identification number: CRD42023422043.

Development of a Single-nucleotide Polymorphism Genotyping Assay for the Rapid Detection of Vancomycin-intermediate Resistance in Staphylococcus aureus Epidemic Lineage ST5

Background

Vancomycin is a treatment option for patients with severe methicillin-resistant Staphylococcus aureus (MRSA) infection. Unfortunately, reduced susceptibility to vancomycin in S. aureus is becoming increasingly common. We developed a method for the rapid and accurate diagnosis of vancomycin-intermediate resistant S. aureus (VISA).

Methods

We performed a microbial genome-wide association study to discriminate between VISA and vancomycin-susceptible S. aureus (VSSA) using 42 whole-genome sequences. A TaqMan single-nucleotide polymorphism (SNP) genotyping assay was developed to detect target SNPs in VISA strains.

Results

Four SNPs in the VISA strains resulting in nonsynonymous amino-acid substitutions were associated with reduced susceptibility to vancomycin: SA_RS01235 (G203S), SA_RS09725 (V171A), SA_RS12250 (I48F), and SA_RS12550 (G478A). These four SNPs were mainly detected in the typical hospital-associated sequence type (ST)5 clonal lineage. The TaqMan assay successfully detected all four SNPs using as little as 0.2 ng DNA per reaction. Using 10 VSSA and VISA clinical strains each, we validated that the assay accurately discriminates between VISA and VSSA.

Conclusions

The TaqMan SNP genotyping assay targeting four SNPs may be an alternative to current standard methods for the rapid detection of vancomycin-intermediate resistance in S. aureus epidemic lineage ST5.

A Photothermally Enhanced Vancomycin-Coated Liquid Metal Antimicrobial Agent with Targeting Capability

The targeted antimicrobial efficacy of Vancomycin decreases significantly over time due to bacterial resistance, whereas Ga-based liquid metals, which are less prone to inducing bacterial resistance, face challenges in achieving targeted antimicrobial effects. To tackle these issues, a highly efficient antimicrobial agent with targeting properties has been developed by combining Ga-based liquid metals and Vancomycin. Moreover, the performance of this antimicrobial agent can be greatly enhanced through the use of near-infrared light. Microscopic observations reveal that Vancomycin can be effectively encapsulated on the surface of liquid metal, facilitated by the presence of the oxide layer. The resulting core–shell structured antimicrobial agent demonstrates notable targeted antimicrobial effects against S. aureus. Antibacterial tests indicate that Vancomycin effectively improves the antibacterial properties of pure liquid metal. Additionally, this study unveils the excellent photothermal conversion capabilities of liquid metal, enabling the antimicrobial agent exposed to 808nm near-infrared light to exhibit significantly strengthened bactericidal performance. In this scenario, the antimicrobial agent can achieve nearly 100% effectiveness. This work enriches the investigation of integrating Ga-based antimicrobial agents with traditional antibiotics, showcasing promising antibacterial effects and establishing the groundwork for subsequent clinical applications.

A defect in cell wall recycling confers antibiotic resistance and sensitivity in Staphylococcus aureus

WalKR is a two-component system that is essential for viability in Gram-positive bacteria that regulates the all-important autolysins in cell wall homeostasis. Further investigation of this essential system is important for identifying ways to address antibiotic resistance. Here, we show that a T101M mutation in walR confers a defect in autolysis, a thickened cell wall, and decreased susceptibility to antibiotics that target lipid II cycle, a phenotype that is reminiscent of the clinical resistance form known as vancomycin intermediate-resistant Staphylococcus aureus. Importantly, this is accompanied by dramatic sensitization to tunicamycin. We demonstrate that this phenotype is due to partial collapse of a pathway consisting of autolysins, AtlA and Sle1, a transmembrane sugar permease, MurP, and GlcNAc recycling enzymes, MupG and MurQ. We suggest that this causes a shortage of substrate for the peptidoglycan biosynthesis enzyme MraY, causing it to be hypersensitive to competitive inhibition by tunicamycin. In conclusion, our results constitute a new molecular model for antibiotic sensitivity in S. aureus and a promising new route for antibiotic discovery.

Clinical Presentation and Management of Methicillin-Resistant Staphylococcus aureus Pericarditis—Systematic Review

In the expanding era of antibiotic resistance, new strains of Staphylococcus aureus have emerged which possess resistance to traditionally used antibiotics (MRSA). Our review aimed to systematically synthesize information on previously described MRSA pericarditis cases. The only criterion for inclusion was the isolation of MRSA from the pericardial space. Our review included 30 adult and 9 pediatric patients (aged: 7 months to 78 years). Comorbid conditions were seen in most adult patients, whereas no comorbidities were noted amongst the pediatric patients. Pericardial effusion was found in 94.9% of cases, with evidence of tamponade in 83.8%. All cases isolated MRSA from pericardial fluid and 25 cases (64.1%) had positive blood cultures for MRSA. Pericardiocentesis and antibiotics were used in all patients. The mortality rate amongst adults was 20.5%, with a mean survival of 21.8 days, and attributed to multi-organ failure associated with septic shock. No mortality was observed in the pediatric population. In adult patients, there was no statistical difference in symptom duration, antibiotic duration, presence of tamponade, age, and sex in relation to survival. Conclusion: MRSA pericarditis often presents with sepsis and is associated with significant mortality. As such, a high clinical suspicion is needed to proceed with proper tests such as echocardiography and pericardiocentesis. In more than one third of the cases, MRSA pericarditis occurs even in the absence of documented bacteremia.

Comparative study on the changes of bacterial species and severity of antimicrobial resistance during 13 years

Background

With the widespread use of broad-spectrum antibiotics, the problem of bacterial resistance has become a global crisis. To monitor bacterial resistance in our hospital, the distribution of specimens, the detection of pathogens and their drug resistance from July 2005 to June 2007 (13 years ago) and July 2018 to June 2020 were compared and analyzed.

Methods

Ordinary specimens (such as sputum, urine, feces, and secretion) were inoculated in blood AGAR media, MacConkey medium, chocolate medium, double SS medium and selective culture medium. Blood, cerebrospinal fluid, pleural effusion, joint cavity effusion and other sterile body fluid samples were inoculated in aerobic and anaerobic blood culture flasks. Automatic microbial identification, drug sensitivity analysis and mass spectrometry analysis were used to determine their drug sensitivity.

Results

Compared with the results obtained 13 years ago, the number of specimens submitted for inspection in the past two years has increased significantly, exhibiting a growth rate of 283%. The changes in the pathogen species were obvious. Gram-positive cocci were the dominant bacteria 13 years ago, and Gram-negative bacilli were the dominant bacteria in the past two years. In addition, the resistance of several major Gram-negative bacilli to piperacillin/tazobactam, cefoperazone/sulbactam, meropenem and imipenem all showed an increasing trend.

Conclusion

The variety of pathogenic bacteria in our hospital has changed significantly in the past two years compared with that 13 years ago, and the clinical isolates of Gram-negative bacilli have increased significantly compared with Gram-positive cocci. In the clinical treatment of anti-infective diseases, antimicrobial agents should be selected according to the bacterial distribution characteristics and drug resistance in each hospital.

Bacterial Skin Infections in Livestock and Plant-Based Alternatives to Their Antibiotic Treatment

Due to its large surface area, the skin is susceptible to various injuries, possibly accompanied by the entrance of infective agents into the body. Commensal organisms that constitute the skin microbiota play important roles in the orchestration of cutaneous homeostasis and immune competence. The opportunistic pathogen Staphylococcus aureus is present as part of the normal biota of the skin and mucous membranes in both humans and animals, but can cause disease when it invades the body either due to trauma or because of the impaired immune response of the host. Colonization of livestock skin by S. aureus is a precursor for majority of bacterial skin infections, which range from boils to sepsis, with the best-characterized being bovine mastitis. Antibiotic treatment of these infections can contribute to the promotion of resistant bacterial strains and even to multidrug resistance. The development of antibiotic resistance to currently available antibiotics is a worldwide problem. Considering the increasing ability of bacteria to effectively resist antibacterial agents, it is important to reduce the livestock consumption of antibiotics to preserve antibiotic effectiveness in the future. Plants are recognized as sources of various bioactive substances, including antibacterial activity towards clinically important microorganisms. This review provides an overview of the current knowledge on the major groups of phytochemicals with antibacterial activity and their modes of action. It also provides a list of currently known and used plant species aimed at treating or preventing bacterial skin infections in livestock.

Systematic review and meta-analysis of the epidemiology of vancomycin-resistance Staphylococcus aureus isolates

BACKGROUND

Vancomycin‑resistant Staphylococcus aureus (VRSA) is a serious public health challenging concern worldwide.

OBJECTIVES

Therefore, the objective of present study of 62 published studies was to evaluate the prevalence of VRSA based on different years, areas, isolate source, antimicrobial susceptibility testing, and the genetic determinants.

METHODS

We searched the relevant articles that focused on the prevalence rates of VRSA in PubMed, Scopus, Embase, and Web of Science from 2000 to 2019. Statistical analyses were conducted using STATA software (version 14.0).

RESULTS

The prevalence of VRSA was 2% before 2006, 5% in 2006-2014, and 7% in 2015-2020 that showed a 3.5-fold increase in the frequency of VRSA between before 2006 and 2020 years. The prevalence of VRSA was 5% in Asia, 1% in Europe, 4% in America, 3% in South America, and 16% in Africa. The frequencies of VRSA isolated from clinical, non-clinical, and mixed samples were 6%, 7%, and 14%, respectively. The prevalence of VRSA was 12% using disk diffusion agar method, 7% using MIC-base methods, and 4% using mixed-methods. The prevalence of vanA, vanB, and vanC1 positive were 71%, 26%, and 4% among VRSA strains. The most prevalent genotype was staphylococcal cassette chromosomemec (SCCmec) II, which accounted for 57% of VRSA. The most prevalent staphylococcal protein A (spa) types were t002, t030, and t037.

CONCLUSION

The prevalence of VRSA has been increasing in recent years particularly in Africa/Asia than Europe/America. The most prevalent of genetic determinants associated with VRSA were vanA and SCCmec II. This study clarifies that the rigorous monitoring of definite antibiotic policy, regular surveillance/control of nosocomial-associated infections and intensive surveillance of vancomycin-resistance are required for preventing emergence and further spreading of VRSA.

Bacterial and Viral Coinfections with the Human Respiratory Syncytial Virus

The human respiratory syncytial virus (hRSV) is one of the leading causes of acute lower respiratory tract infections in children under five years old. Notably, hRSV infections can give way to pneumonia and predispose to other respiratory complications later in life, such as asthma. Even though the social and economic burden associated with hRSV infections is tremendous, there are no approved vaccines to date to prevent the disease caused by this pathogen. Recently, coinfections and superinfections have turned into an active field of study, and interactions between many viral and bacterial pathogens have been studied. hRSV is not an exception since polymicrobial infections involving this virus are common, especially when illness has evolved into pneumonia. Here, we review the epidemiology and recent findings regarding the main polymicrobial infections involving hRSV and several prevalent bacterial and viral respiratory pathogens, such as Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Klebsiella pneumoniae, human rhinoviruses, influenza A virus, human metapneumovirus, and human parainfluenza viruses. As reports of most polymicrobial infections involving hRSV lack a molecular basis explaining the interaction between hRSV and these pathogens, we believe this review article can serve as a starting point to interesting and very much needed research in this area.

Eradication of vancomycin-resistant Staphylococcus aureus on a mouse model of third-degree burn infection by melittin: An antimicrobial peptide from bee venom

Third-degree burn infections caused by antibiotic-resistant bacteria are of high clinical concern. Chemical antibiotics are not promising in eradication of bacterial infections. In this challenging condition, antimicrobial peptides (AMPs) are recently introduced as novel promising agents to overcome the issue. Accordingly, our study aimed to evaluate the efficiency of 'melittin' as natural peptide in bee venom, in eradicating vancomycin resistant Staphylococcus aureus (VRSA) on a mouse model of third-degree burn infection. In vitro pharmacological value of melittin was determined by examining its inhibitory and killing activities on VRSA isolates at different doses and time periods. The action mechanism of 'melittin' was evaluated by fluorescent release assay and Field Emission Scanning Electron Microscopy (FE-SEM) analyses. In vivo activity and toxicity of melittin were also examined on a mouse model of third-degree burn infection. The Minimum Inhibitory Concentration (MIC) and the Minimum Bactericidal Concentration (MBC) of melittin on all isolates ranged from '0.125-2 μg/mL' and '0.125-4 μg/mL', respectively. Rapid antibacterial activity of melittin on VRSA isolates was demonstrated by killing kinetics assays. Fluorometric and FE-SEM analyses indicated the membranolytic effects of melittin on VRSA isolates. The colonized VRSA bacteria were eradicated by melittin at 16 μg, in a single dose. No dermal toxicity and in vivo hemolysis were observed in the examined mice. The lack of in vivo toxicity of melittin along with its potent antibacterial activity indicated its promising therapeutic value as a topical drug against S. aureus associated third-degree burn infections.

Lessons Learned from an Experience with Vancomycin-Intermediate Staphylococcus aureus Outbreak in a Newly Built Secondary Hospital in Korea

A vancomycin-intermediate Staphylococcus aureus (VISA) outbreak occurred in an intensive care unit (ICU) in South Korea. We aimed to investigate the condition that led to the VISA outbreak and seek measures to prevent further spread of the multidrug-resistant organism. A total of three VISA isolates were obtained from two patients and a health care worker (HCW) in a newly built 450-bed secondary hospital. Extensive screening of close contacts for VISA in terms of space sharing and physical contact, irrespective of contact time, was performed. Furthermore, multilocus sequence type, staphylococcal cassette chromosome mec type, and spa type profiles were determined for all VISA isolates. The relationship between vancomycin use and the minimum inhibitory concentration (MIC) of S. aureus was also investigated. Molecular typing showed that the strains of the three VISA isolates were identical, indicating horizontal hospital transmission. We assumed that VISA colonised in the HCW could have transmitted to the two patients, which resulted in one infection and one colonisation. The affected HCW was excused from work and was decolonised with mupirocin. Five weeks after the interventions, no additional VISA isolates were identified. No relationship between vancomycin use and MIC of S. aureus was identified. Extensive screening of contacts in addition to decolonisation is crucial in preventing the further spread of VISA.

Photodynamic therapy for treatment of Staphylococcus aureus infections

BACKGROUND

Staphylococcus aureus is a Gram-positive spherical bacterium that commonly causes various infections which can range from superficial to life-threatening. Hospital strains of S. aureus are often resistant to antibiotics, which has made their treatment difficult in recent decades. Other therapeutic alternatives have been postulated to overcome the drawbacks of antibiotic multi-resistance. Of these, photodynamic therapy (PDT) is a promising approach to address the notable shortage of new active antibiotics against multidrug-resistant S. aureus. PDT combines the use of a photosensitizer agent, light, and oxygen to eradicate pathogenic microorganisms. Through a systematic analysis of published results, this work aims to verify the usefulness of applying PDT in treating multidrug-resistant S.aureus infections.

METHODS

This review was based on a bibliographic search in various databases and the analysis of relevant publications.

RESULTS

There is currently a large body of evidence demonstrating the efficacy of photodynamic therapy in eliminating S.aureus strains. Both biofilm-producing strains, as well as multidrug-resistant strains.

CONCLUSION

We conclude that there is sufficient scientific evidence that PDT is a useful adjunct to traditional antibiotic therapy for treating S. aureus infections. Clinical application through appropriate trials should be introduced to further define optimal treatment protocols, safety and efficay.

Association between fluoroquinolone resistance and MRSA genotype in Alexandria, Egypt

Antimicrobial stewardship isn't strictly observed in most Egyptian hospitals, raising antibiotic resistance. Epidemiology of Egyptian MRSA isolates, or associations with resistance to other antibiotics remain largely unknown. We identified MRSA genotypes in Alexandria Main University Hospital (AMUH) and investigated rates of moxifloxacin resistance, an alternative MRSA treatment, among different genotypes. Antibiotic susceptibility of 72 MRSA clinical isolates collected in 2015 from AMUH was determined by disc diffusion and broth microdilution. spa- and Staphylococcal Cassette Chromosome mec (SCCmec) typing were performed; with multi-locus sequence typing conducted on isolates representing major genotypes. Resistance to moxifloxacin, levofloxacin and ciprofloxacin were 69%, 78% and 96%, respectively. spa type t037 (57%) was commonest, followed by t127 (12.5%), t267 (8%) and t688 (6%). SCCmec III predominated (57%), all of these were moxifloxacin resistant and 97.6% t037 (ST241). SCCmec IV, IV E and V represented 15%, 7% and 11% of the isolates, respectively, 79% of these were moxifloxacin susceptible and of different spa types. t127 (ST-1) was associated with SCCmec V in 56% of the isolates, mostly moxifloxacin susceptible. Moxifloxacin resistance was high, most resistant isolates belonged to t037 and SCCmec III, suggesting local dissemination and antibiotic pressure. We recommend caution in treating MRSA infections with moxifloxacin.

Global prevalence and distribution of vancomycin resistant, vancomycin intermediate and heterogeneously vancomycin intermediate Staphylococcus aureus clinical isolates: a systematic review and meta-analysis

Vancomycin-resistant Staphylococcus aureus (VRSA), Vancomycin-intermediate S. aureus (VISA) and heterogeneous VISA (hVISA) are subject to vancomycin treatment failure. The aim of the present study was to determine their precise prevalence and investigate prevalence variability depending on different years and locations. Several international databases including Medline (PubMed), Embase and Web of Sciences were searched (data from 1997 to 2019) to identify studies that addressed the prevalence of VRSA, VISA and hVISA among human clinical isolates around the world. Subgroup analyses and meta-regression were conducted to indicate potential source of variation. Publication bias was assessed using Egger's test. Statistical analyses were conducted using STATA software (version 14.0). Data analysis showed that VRSA, VISA and hVISA isolates were reported in 23, 50 and 82 studies, with an overall prevalence of 1.5% among 5855 S. aureus isolates, 1.7% among 22,277 strains and 4.6% among 47,721 strains, respectively. The overall prevalence of VRSA, VISA, and hVISA before 2010 was 1.2%, 1.2%, and 4%, respectively, while their prevalence after this year has reached 2.4%, 4.3%, and 5.3%. The results of this study showed that the frequency of VRSA, VISA and hVISA after 2010 represent a 2.0, 3.6 and 1.3-fold increase over prior years. In a subgroup analysis of different strain origins, the highest frequency of VRSA (3.6%) and hVISA (5.2%) was encountered in the USA while VISA (2.1%) was more prevalent in Asia. Meta-regression analysis showed significant increasing of VISA prevalence in recent years (p value ≤ 0.05). Based on the results of case reports (which were not included in the calculations mentioned above), the numbers of VRSA, VISA and hVISA isolates were 12, 24 and 14, respectively, among different continents. Since the prevalence of VRSA, VISA and hVISA has been increasing in recent years (especially in the Asian and American continents), rigorous monitoring of vancomycin treatment, it's the therapeutic response and the definition of appropriate control guidelines depending on geographical regions is highly recommended and essential to prevent the further spread of vancomycin-resistant S. aureus.

Prospective Study of Irrational Prescription of Teicoplanin in a Large Academic Hospital: A Dilemma of Antimicrobial Resistance

Objective:

Teicoplanin is an antibiotic used to treat severe Gram-positive infections, especially those caused by methicillin-resistant Staphylococcus aureus (MRSA). In this study, we aimed to evaluate the pattern of teicoplanin rational prescribing to identify the factors which affected rational utilization. In addition, the teicoplanin minimum inhibitory concentration (MIC) was assessed in randomly selected isolates.

Methods:

In this descriptive-analytical prospective study, a total of 256 patients were randomly selected to evaluate the pattern of teicoplanin use. The required data were gathered to assess the appropriateness of teicoplanin usage. Also, 100 teicoplanin Etests were used for measuring the MIC.

Findings:

The results showed that the appropriateness rate of teicoplanin usage was 21.9%. The mean MIC was 2.24 ± 5.47 mg/L for the MRSA cultures (33 cultures), including 32 sensitive cultures (97%). In addition, the mean MIC was 28.71 ± 8.29 mg/L for the vancomycin-resistant enterococci (VRE) cultures (67 cultures), including five sensitive cultures (7.5%). Moreover, the analysis revealed that only the hospitalization ward was statistically significantly related to irrational usage (P = 0.014).

Conclusion:

The high prevalence of the inappropriate use of teicoplanin will lead to the development of antimicrobial resistance. Furthermore, the high rate of VRE cultures resistant to teicoplanin proves that teicoplanin has no advantage over vancomycin for treating VRE infections. Finally, we recommend guidelines' development for the appropriate administration of teicoplanin.

Incidence of Vancomycin Resistant Phenotype of the Methicillin Resistant Staphylococcus aureus Isolated from a Tertiary Care Hospital in Lahore

Staphylococcus aureus (S. aureus)-associated infections are one of the major threats to public health. The aim of the present study was to determine the antibiotic resistance pattern as well as the genetic characterization of methicillin and vancomycin resistant S. aureus (VRSA) isolated from a tertiary care hospital in Lahore. The S. aureus isolates were isolated from different clinical samples, identified by biochemical testing, and subjected to antibiotic susceptibility testing via the disc diffusion method or broth microdilution method. The methicillin resistance gene (mecA) and vancomycin resistance gene (vanA) were amplified by the polymerase chain reaction. The S. aureus isolates showed high incidences of resistance against methicillin (76%) and moderate incidences of resistance to vancomycin (14%). Isolates were also resistant to several other drugs, such as cefoxitin (76%), ertapenem (83%), ampicillin (81%), tobramycin (78%), moxifloxacin (76%), and tetracycline (74%). An encouraging finding was that 98% of isolates were susceptible to tigecycline, indicating its possible role in the treatment of methicillin-resistant Staphylococcus aureus (MRSA) and VRSA, as well as the multi-drug resistant S. aureus. The mecA gene was detected in 33.3% of tested isolates (10/30), while the vanA gene was also detected in 30% (9/30) of the tested isolates. In conclusion, the frequent presence of methicillin and vancomycin resistance in S. aureus appraises the cautious use of these antibiotics in clinical practices. Furthermore, it is suggested that there should be continuous monitoring of tigecycline treatments in clinical setups in order to delay the development of resistance against it.

Intensive Patient Treatment

Intensive care units (ICUs) are treating hospital’s poorest patients that need medical assistance during the most extreme period of their life. Intensive patients are treated with extensive invasive procedures, which may cause a risk of hospital infections in 10–30% of the cases. More than half of these infections can be prevented. The patients are often admitted directly from outside the hospital or from abroad with trauma after accidents, serious heart and lung conditions, sepsis and other life-threatening diseases. Infection or carrier state of microbes is often unknown on arrival and poses a risk of transmission to other patients, personnel and the environment. Patients that are transferred between different healthcare levels and institutions with unknown infection may be a particular risk for other patients. In spite of the serious state of the patients, many ICUs have few resources and are overcrowded and understaffed, with a lack of competent personnel. ICU should have a large enough area and be designed, furnished and staffed for a good, safe and effective infection control. The following chapter is focused on practical measures to reduce the incidence of infections among ICU patients.

Methicillin-Resistant Staphylococcus aureus: Molecular Characterization, Evolution, and Epidemiology

Staphylococcus aureus, a major human pathogen, has a collection of virulence factors and the ability to acquire resistance to most antibiotics. This ability is further augmented by constant emergence of new clones, making S. aureus a "superbug." Clinical use of methicillin has led to the appearance of methicillin-resistant S. aureus (MRSA). The past few decades have witnessed the existence of new MRSA clones. Unlike traditional MRSA residing in hospitals, the new clones can invade community settings and infect people without predisposing risk factors. This evolution continues with the buildup of the MRSA reservoir in companion and food animals. This review focuses on imparting a better understanding of MRSA evolution and its molecular characterization and epidemiology. We first describe the origin of MRSA, with emphasis on the diverse nature of staphylococcal cassette chromosome mec (SCCmec). mecA and its new homologues (mecB, mecC, and mecD), SCCmec types (13 SCCmec types have been discovered to date), and their classification criteria are discussed. The review then describes various typing methods applied to study the molecular epidemiology and evolutionary nature of MRSA. Starting with the historical methods and continuing to the advanced whole-genome approaches, typing of collections of MRSA has shed light on the origin, spread, and evolutionary pathways of MRSA clones.

Methicillin-resistant Staphylococcus aureus with reduced vancomycin susceptibility in Taiwan

Staphylococcus aureus is a versatile pathogen which can cause various mild to life-threatening infectious diseases. The evolution of S. aureus resistance is notorious, from penicillin and oxacillin to vancomycin. Vancomycin, introduced in 1956, was once considered a most reliable antibiotic for methicillin-resistant S. aureus (MRSA); unfortunately, the first strain of S. aureus with decreased susceptibility to vancomycin emerged in 1996. Vancomycin has been approved in Taiwan since 1983, and the prevalence rates of heteroresistant vancomycin-intermediate S. aureus (hVISA) and vancomycin-intermediate S. aureus (VISA) in 2003 were 0.7% and 0.2%, respectively. However, a ten-fold increase of hVISA and VISA to 10% and 2.7%, respectively, in 2012-2013 could indicate a challenging clinical situation in Taiwan. The most commonly reported staphylococcal cassette chromosome mec (SCCmec) types of hVISA and VISA are usually SCCmec type III or II, typical nosocomial MRSA strains. Preventing the spread of resistant pathogens through infection control interventions and judicious antibiotic stewardship is a serious medical issue.

Empirical antibiotics targeting gram-positive bacteria for the treatment of febrile neutropenic patients with cancer

BACKGROUND

The pattern of infections among neutropenic patients with cancer has shifted in the last decades to a predominance of gram-positive infections. Some of these gram-positive bacteria are increasingly resistant to beta-lactams and necessitate specific antibiotic treatment.

OBJECTIVES

To assess the effectiveness of empirical anti-gram-positive (antiGP) antibiotic treatment for febrile neutropenic patients with cancer in terms of mortality and treatment failure. To assess the rate of resistance development, further infections and adverse events associated with additional antiGP treatment.

SEARCH METHODS

For the review update we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2017, Issue 2), MEDLINE (May 2012 to 2017), Embase (May 2012 to 2017), LILACS (2012 to 2017), conference proceedings, ClinicalTrials.gov trial registry, and the references of the included studies. We contacted the first authors of all included and potentially relevant trials.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing one antibiotic regimen versus the same regimen with the addition of an antiGP antibiotic for the treatment of febrile neutropenic patients with cancer.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial eligibility and risk of bias, and extracted all data. Risk ratios (RR) with 95% confidence intervals (CIs) were calculated. A random-effects model was used for all comparisons showing substantial heterogeneity (I2 > 50%). Outcomes were extracted by intention-to-treat and the analysis was patient-based whenever possible.

MAIN RESULTS

Fourteen trials and 2782 patients or episodes were included. Empirical antiGP antibiotics were tested at the onset of treatment in 12 studies, and for persistent fever in two studies. The antiGP treatment was a glycopeptide in nine trials. Eight studies were assessed in the overall mortality comparison and no significant difference was seen between the comparator arms, RR of 0.90 (95% CI 0.64 to 1.25; 8 studies, 1242 patients; moderate-quality data). Eleven trials assessed failure, including modifications as failures, while seven assessed overall failure disregarding treatment modifications. Failure with modifications was reduced, RR of 0.72 (95% CI 0.65 to 0.79; 11 studies, 2169 patients; very low-quality data), while overall failure was the same, RR of 1.00 (95% CI 0.79 to 1.27; 7 studies, 943 patients; low-quality data). Sensitivity analysis for allocation concealment and incomplete outcome data did not change the results. Failure among patients with gram-positive infections was reduced with antiGP treatment, RR of 0.56 (95% CI 0.38 to 0.84, 5 studies, 175 patients), although, mortality among these patients was not changed.Data regarding other patient subgroups likely to benefit from antiGP treatment were not available. Glycopeptides did not increase fungal superinfection rates and were associated with a reduction in documented gram-positive superinfections. Resistant colonisation was not documented in the studies.

AUTHORS' CONCLUSIONS

Based on very low- or low-quality evidence using the GRADE approach and overall low risk of bias, the current evidence shows that the empirical routine addition of antiGP treatment, namely glycopeptides, does not improve the outcomes of febrile neutropenic patients with cancer.

Antimicrobial resistance in healthcare, agriculture and the environment: the biochemistry behind the headlines

The crisis of antimicrobial resistance (AMR) is one of the most serious issues facing us today. The scale of the problem is illustrated by the recent commitment of Heads of State at the UN to coordinate efforts to curb the spread of AMR infections. In this review, we explore the biochemistry behind the headlines of a few stories that were recently published in the public media. We focus on examples from three different issues related to AMR: (i) hospital-acquired infections, (ii) the spread of resistance through animals and/or the environment and (iii) the role of antimicrobial soaps and other products containing disinfectants in the dissemination of AMR. Although these stories stem from three very different settings, the underlying message in all of them is the same: there is a direct relationship between the use of antimicrobials and the development of resistance. In addition, one type of antimicrobial could select for cross-resistance to another type and/or for multidrug resistance. Therefore, we argue the case for increased stewardship to not only cover clinical use of antibiotics, but also the use of antimicrobials in agriculture and stewardship of our crucially important biocides such as chlorhexidine.

Validation of the AlamarBlue® Assay as a Fast Screening Method to Determine the Antimicrobial Activity of Botanical Extracts

Plant compounds are a potential source of new antimicrobial molecules against a variety of infections. Plant extracts suppose complex phytochemical libraries that may be used for the first stages of the screening process for antimicrobials. However, their large variability and complexity require fast and inexpensive methods that allow a rapid and adequate screening for antimicrobial activity against a variety of bacteria and fungi. In this study, a multi-well plate assay using the AlamarBlue® fluorescent dye was applied to screen for antimicrobial activity of several botanical extracts and the data were correlated with microbial colony forming units (CFU). This correlation was performed for three pathogenic model microorganisms: Escherichia coli (Gram negative bacteria), Staphylococcus aureus (Gram positive bacteria) and for the yeast-like fungi Candida albicans. A total of ten plant extracts from different Mediterranean plants, including several Cistus and Hibiscus species, were successfully tested. HPLC-DAD-ESI-MS/MS analysis was utilized for the characterization of the extracts in order to establish structure-activity correlations. The results show that extracts enriched in ellagitannins and flavonols are promising antibacterial agents against both Gram positive and Gram negative bacteria. In contrast, phenolic acids, anthocyanidins and flavonols may be related to the observed antifungal activity.

Vancomycin heteroresistant community associated methicillin-resistant Staphylococcus aureus ST72-SCCmecIVa strain colonizing the nostrils of a five-year-old Spanish girl

BACKGROUND AND OBJECTIVES

During a community methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization study, an MRSA strain with vancomycin hetero-resistance (h-VISA) was isolated from a five year-old girl with tetralogy of Fallot without previous exposure to vancomycin. An extended nasal colonization study was performed on all her close relatives.

RESULTS

Only the patient and her sister were colonized by an h-VISA MRSA strain (clone USA 700, ST72, t148, agr 1 and SCCmec IVa). Mupirocin decolonisation was effective in the elder sister. A new nasal decolonisation in the younger girl using fusidic acid was also successful. However, after decolonisation both sisters were colonized by a methicillin-susceptible S. aureus (ST30, t012 and agr 3) previously isolated from their mother's nostrils.

CONCLUSION

As S. aureus have a great capacity to spread among people in close contact, knowledge of a patients' colonization status, tracing contacts, and a correct management are critical issues for the successful containment of multiresistant staphylococci.

Population Genomics of Reduced Vancomycin Susceptibility in Staphylococcus aureus

The increased prevalence of vancomycin-intermediate Staphylococcus aureus (VISA) is an emerging health care threat. Genome-based comparative methods hold great promise to uncover the genetic basis of the VISA phenotype, which remains obscure. S. aureus isolates were collected from a single individual that presented with recurrent staphylococcal bacteremia at three time points, and the isolates showed successively reduced levels of vancomycin susceptibility. A population genomic approach was taken to compare patient S. aureus isolates with decreasing vancomycin susceptibility across the three time points. To do this, patient isolates were sequenced to high coverage (~500×), and sequence reads were used to model site-specific allelic variation within and between isolate populations. Population genetic methods were then applied to evaluate the overall levels of variation across the three time points and to identify individual variants that show anomalous levels of allelic change between populations. A successive reduction in the overall levels of population genomic variation was observed across the three time points, consistent with a population bottleneck resulting from antibiotic treatment. Despite this overall reduction in variation, a number of individual mutations were swept to high frequency in the VISA population. These mutations were implicated as potentially involved in the VISA phenotype and interrogated with respect to their functional roles. This approach allowed us to identify a number of mutations previously implicated in VISA along with allelic changes within a novel class of genes, encoding LPXTG motif-containing cell-wall-anchoring proteins, which shed light on a novel mechanistic aspect of vancomycin resistance. IMPORTANCE The emergence and spread of antibiotic resistance among bacterial pathogens are two of the gravest threats to public health facing the world today. We report the development and application of a novel population genomic technique aimed at uncovering the evolutionary dynamics and genetic determinants of antibiotic resistance in Staphylococcus aureus. This method was applied to S. aureus cultures isolated from a single patient who showed decreased susceptibility to the vancomycin antibiotic over time. Our approach relies on the increased resolution afforded by next-generation genome-sequencing technology, and it allowed us to discover a number of S. aureus mutations, in both known and novel gene targets, which appear to have evolved under adaptive pressure to evade vancomycin mechanisms of action. The approach we lay out in this work can be applied to resistance to any number of antibiotics across numerous species of bacterial pathogens.

Evaluating Vancomycin Use at a Pediatric Hospital: New Approaches and Insights

Objectives:

To characterize vancomycin use at a pediatric tertiary-care hospital, to discriminate between initial (≤ 72 hours) and prolonged (> 72 hours) inappropriate use, and to define patient characteristics associated with inappropriate use.

Design:

Vancomycin courses were retrospectively reviewed using an algorithm modeled on HICPAC guidelines. Data were collected regarding patient demographics, comorbidities, other medication use, and nosocomial infections. The association between each variable and the outcome of inappropriate use was determined by longitudinal regression analysis. A multi-variable model was constructed to assess risk factors for inappropriate initial and prolonged vancomycin use.

Setting:

A pediatric tertiary-care medical center.

Patients:

Children older than 1 year who received intravenous vancomycin from November 2000 to June 2001.

Results:

Three hundred twenty-seven vancomycin courses administered to 260 patients were evaluated for appropriateness. Of initial courses, 114 (35%) were considered inappropriate. Of 143 prolonged courses, 103 (72%) were considered inappropriate. Multivariable risk factor analysis identified the following variables as significantly associated with inappropriate initial use: admission to the surgery service, having a malignancy, receipt of a stem cell transplant, and having received a prior inappropriate course of vancomycin. No variables were identified as significant risk factors for inappropriate prolonged use.

Conclusions:

Substantial inappropriate use of vancomycin was identified. Prolonged inappropriate use was a particular problem. This risk factor analysis suggests that interventions targeting patients admitted to certain services or receiving multiple courses of vancomycin could reduce inappropriate use.

Antibiotic-eluting hydrophilized PMMA bone cement with prolonged bactericidal effect for the treatment of osteomyelitis

Osteomyelitis is still considered to be one of the major challenges for orthopedic surgeons despite advanced antiseptic surgical procedures and pharmaceutical therapeutics. In this study, hydrophilized poly(methyl methacrylate) (PMMA) bone cements containing Pluronic F68 (EG79PG28EG79) as a hydrophilic additive and vancomycin ( F68-VA cements) were prepared to allow the sustained release of the antibiotic for adequate periods of time without any significant loss of mechanical properties. The compressive strengths of the bone cements with Pluronic F68 compositions less than 7 wt% were not significantly different compared with the control vancomycin-loaded bone cement ( VA cement). The F68 (7 wt%)-VA cement showed sustained release of the antibiotic for up to 11 weeks and almost 100% release from the bone cement. It also prohibited the growth of S. aureus (zone of inhibition) over six weeks (the required period to treat osteomyelitis), and it did not show any notable cytotoxicity. From an animal study using a femoral osteomyelitis rat model, it was observed that the F68 (7 wt%)-VA cement was effective for the treatment of osteomyelitis, probably as a result of the prolonged release of antibiotic from the PMMA bone cement. On the basis of these findings, it can be suggested that the use of Pluronic F68 as a hydrophilic additive for antibiotic-eluting PMMA bone cement can be a promising strategy for the treatment of osteomyelitis.

Phenotypic Characteristics of Vancomycin-Non-Susceptible Staphylococcus aureus

Background:

Staphylococcus aureus, with reduced vancomycin susceptibility, is probably under the regulation of several genes and various express phenotypes.

Objectives:

This study aimed to investigate the phenotypic differences between vancomycin-susceptible S. aureus (VSSA), vancomycin-intermediate S. aureus (VISA), and heterogeneous VISA (hVISA) isolates.

Materials and Methods:

A total of 130 methicillin-resistant S. aureus (MRSA) isolates were studied, including 49 VSSA, 28 hVISA, and 5 VISA isolates from blood cultures and 48 isolates (two VSSA, six hVISA, and 40 VISA) derived in vitro (laboratory-induced/sub-passaged). Their phenotypes were examined using a coagulase tube test, colony spreading on soft agar, and urease activity. The SCCmec and agr typing were performed using multiplex PCR.

Results:

Most of the MRSA isolates were SCCmec III-agr I (84.5%), followed by SCCmec II-agr II (11.8%). The average plasma coagulation time of vancomycin-non-susceptible isolates was longer than that of the susceptible isolates (12 vs. 2.6 hours). Four hVISA (P = 0.023) and nine VISA (P < 0.001) isolates yielded a negative coagulase test after 24-hour incubation. The percentage of VSSA isolates showing non-spreading colonies (accessory gene regulator (agr) dysfunction) was significantly lower than in the VISA group (P = 0.013), but no significant difference was found between VSSA and hVISA. The VISA group showed higher urease activity than that of the VSSA and hVISA groups (P = 0.002).

Conclusions:

There were diverse phenotypic changes among vancomycin-non-susceptible S. aureus isolates. This may be due to the variety of related regulatory systems. The diversity of phenotypic expression may result in its misidentification in routine laboratory checks.

Structural and functional insight into the different oxidation states of SAV1875 from Staphylococcus aureus

Crystal structures of the wild-type and various mutants of SAV1875 with different cysteine oxidation states were elucidated. SAV1875 functions as a chaperone and the redox state of Cys105 may play an important role.

Staphylococcus aureus Bacteremia in Children: Changes During Eighteen Years

BACKGROUND

Staphylococcus aureus is a major cause of bacteremia in children and is associated with high morbidity. Complete data are lacking on the incidence, related risk factors and mortality associated with this infection.

METHODS

Descriptive study including patients younger than 16 years admitted to a tertiary reference hospital, with blood cultures exclusively positive for S. aureus. Four study periods were established: period 1, 1995-1999; period 2, 2000-2002; period 3, 2006-2008 and period 4, 2010-2012.

RESULTS

In total, 269 episodes of S. aureus bacteremia (SAB) occurred in 242 patients. Over the total time studied, the incidence increased from 1.3 to 3.3 cases per 1000 patients hospitalized (relative risk: 2.71; 95% confidence interval: 1.85-3.95) and mortality decreased from 18% to 6% (P = 0.008). There were no differences in the resistance patterns of S. aureus strains. The prevalence of methicillin-resistant S. aureus (MRSA) increased from 3% to 13% between periods 1 and 2 and decreased from 14% to 3% between periods 3 and 4 (P = 0.011). The 30-day cumulative mortality was 3.3%, and the SAB-related mortality was 1.5%. Nosocomial acquisition and age 12-16 years were factors independently related with death on multivariate analysis.

CONCLUSIONS

The incidence of SAB tripled during the years studied but remained stable in the last period. Antimicrobial resistances did not increase. Although a decrease in mortality was documented, approximately half the 30-day cumulative mortality was caused by SAB.

Systematic Review and Meta-Analysis of the Epidemiology of Vancomycin-Intermediate and Heterogeneous Vancomycin-Intermediate Staphylococcus aureus Isolates

BACKGROUND

Vancomycin-intermediate Staphylococcus aureus (VISA) and heterogeneous VISA (hVISA) are associated with vancomycin treatment failure, and are becoming an increasing public health problem. Therefore, we undertook this study of 91 published studies and made subgroup comparisons of hVISA/VISA incidence in different study years, locations, and types of clinical samples. We also analyzed the genetic backgrounds of these strains.

METHODS

A systematic literature review of relevant articles published in PubMed and EMBASE from January 1997 to August 2014 was conducted. We selected and assessed journal articles reporting the prevalence rates of hVISA/VISA.

RESULTS

The pooled prevalence of hVISA was 6.05% in 99,042 methicillin-resistant S. aureus (MRSA) strains and that of VISA was 3.01% in 68,792 MRSA strains. The prevalence of hVISA was 4.68% before 2006, 5.38% in 2006-2009, and 7.01% in 2010-2014. VISA prevalence was 2.05%, 2.63%, and 7.93%, respectively. In a subgroup analysis of different isolation locations, the prevalence of hVISA strains was 6.81% in Asia and 5.60% in Europe/America, and that of VISA was 3.42% and 2.75%, respectively. The frequencies of hVISA isolated from blood culture samples and from all clinical samples were 9.81% and 4.68%, respectively, and those of VISA were 2.00% and 3.07%, respectively. The most prevalent genotype was staphylococcal cassette chromosome mec (SCCmec) II, which accounted for 48.16% and 37.74% of hVISA and VISA, respectively. Sequence Type (ST) 239 was most prevalent.

CONCLUSION

The prevalence of hVISA/VISA has been increasing in recent years, but has been grossly underestimated. Its incidence is higher in Asia than in Europe/America. hVISA is isolated from blood culture samples more often than from other samples. These strains are highly prevalent in epidemic MRSA strains. This study clarifies the epidemiology of hVISA/VISA and indicates that the detection of these strains and the control of nosocomial infections must be strengthened.

A rare case of infectious colitis

Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for numerous infectious processes. Gastrointestinal tract involvement is rather rare and only a handful of cases of MRSA colitis have been reported in North America. We present a case of MRSA colitis in an adult without apparent risk factors. Abdominal computed tomography (CT) showed thickening of the sigmoid colon, indicative of colitis, and empiric therapy with ciprofloxacin and metronidazole was started. Initial work-up for infection—including blood and stool cultures, and stool Clostridium difficile toxin assay—was negative. The patient’s clinical status improved but his diarrhea did not abate. Repetition of stool culture demonstrated luxuriant growth of MRSA sensitive to vancomycin. Oral vancomycin was administered and the patient’s symptoms promptly ceased.