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.

Reservoirs of Nosocomial Pathogens in Intensive Care Units: A Systematic Review

Background

Nosocomial pathogens are known to exacerbate morbidity and mortality in contemporary critical healthcare. Hospital fomites, which include inanimate surfaces, have been identified as "breeding grounds" for pathogens that cause nosocomial infections. This systematic review aimed to deliver incisive insights on nosocomial pathogens in intensive care units (ICUs) and the role of fomites as potential reservoirs for their transmission.

Method

An extensive exploration of electronic databases, including PubMed and Scopus, from 1990 to 2023, was carried out between 25th and 29th May 2023, per standard PRISMA guidelines. Information were extracted from articles that reported on fomites in the ICU. Studies that did not quantitatively report the fomite contamination, and those that exclusively took samples from patients in the ICU were excluded from the analysis.

Results

About 40% of the total samples collected on fomites from all the studies yielded microbial growth, with species of Staphylococcus being the most predominant. Other prevalent microbes were Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, Candida spp., Enterococcus sp., and Enterobacter sp. The neonatal intensive care unit (NICU) had the highest proportion of contaminated fomites. Among known fomites, the sphygmomanometer exhibited a 100% detection rate of nosocomial pathogens. This included E. aerogenes, Staphylococcus aureus, coagulase-negative Staphylococci (CoNS), E. coli, and K. pneumoniae. Multidrug-resistant (MDR) bacteria, such as methicillin-resistant S. aureus (MRSA), vancomycin-resistant Enterococci (VRE), extended-spectrum beta-lactamase (ESBL)-producing E. coli, and MDR Pseudomonas aeruginosa were commonly isolated on fomites in the ICUs.

Conclusion

Many fomites that are readily used in patient care in the ICU harbour nosocomial pathogens. The most common fomite appeared to be mobile phones, sphygmomanometers, and stethoscopes, with Staphylococcus being the most common contaminant. Consequently, the need for rigorous disinfection and sterilization protocols on fomites in the ICU cannot be overemphasized. Additionally, heightened awareness on the subject among health professionals is crucial to mitigating the risk and burden of nosocomial infections caused by drug-resistant bacteria.

ArtinM Grafted Phospholipid Nanoparticles for Enhancing Antibiotic Cellular Uptake Against Intracellular Infection

Background and Aim

An antimicrobial delivery in the form of surface-modified lectin of lipid nanoparticles was proposed to improve cellular accumulation. ArtinM, an active toll-like receptor 2 (TLR2) agonist lectin isolated from cempedak (Arthocarpus integrifolia) seeds, was selected to induce cellular engulfment of nanoparticles within infected host cells.

Materials and Methods

Lipid nanoparticles were prepared using the emulsification technique before electrostatic adsorption of artinM. The formula comprising of rifampicin, soy phospholipid, and polysorbate 80 was optimized by Box-Behnken design to produce the desired particle size, entrapment efficiency, and drug loading. The optimum formula was characterized for morphology, in vitro release, and cellular transport.

Results and Discussion

Soy phospholipid showed a profound effect on controlling drug loading and entrapment efficiency. Owing to its surface activity, polysorbate 80 contributed significantly to reduce particle size; however, a higher ratio to lipid concentration resulted in a decrease of rifampicin encapsulation. The adsorption of artinM on the surface of nanoparticles was accomplished by electrostatic binding at pH 4, where this process maintained the stability of encapsulated rifampicin. A high proportion of artinM adsorbed on the surface of the nanoparticles shown by haemagglutination assay, zeta potential measurement, and transmission electron microscopy imaging. Cellular uptake revealed by confocal microscopy showed the success in transporting Nile-red labelled nanoparticles across fibroblast cells.

Conclusion

The delivery system of nanoparticles bearing artinM becomes a potential platform technology for antibiotic targeting in the treatment of life-threatening chronic diseases caused by intracellular infections.

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.

Importance of Multifaceted Approaches in Infection Control: A Practical Experience from an Outbreak Investigation

BACKGROUND

This study presents the results of a multidisciplinary, nosocomial MRSA outbreak investigation in an 8-bed medical intensive care unit (ICU). The identification of seven MRSA positive patients in the beginning of 2014 led to the closure of the ward for several weeks. A multidisciplinary, retrospective investigation was initiated in order to identify the reason and the source for the outbreak, describe MRSA transmission in the department and identify limitations in infection control.

METHODS

The investigation comprised an epidemiological description of MRSA cases from 2012 to 2014 and a characterization of MRSA isolates, including phage-, spa- and PFGE-typing. Additionally, MRSA screening was performed from the hospital staff and the environment. To identify the reason for the outbreak, work-related, psychological and behavioral factors were investigated by impartial audits and staff interviews.

RESULTS

Thirty-one MRSA cases were registered during the study period, and 36 isolates were investigated. Molecular typing determined the outbreak strain (phage type 54/812, PFGE type A4, spa type t003) and identified the probable index case. Nasal carriage in one employee and a high environmental contamination with the outbreak strain was documented. Important gaps in nursing procedures and general management were identified. Elevated stress levels and communication problems preceded the outbreak. Compliance with hand hygiene and isolation procedures was evaluated as appropriate.

CONCLUSION

This study demonstrates the complexity of controlling hospital-associated infections. The combined use of different typing methods is beneficial for outbreak investigations. Psychological, behavioral and other work-related factors have an important impact on the spread of nosocomial pathogens. These factors should be addressed and integrated in routine infection control practice.

Evolving resistance among Gram-positive pathogens

Antimicrobial therapy is a key component of modern medical practice and a cornerstone for the development of complex clinical interventions in critically ill patients. Unfortunately, the increasing problem of antimicrobial resistance is now recognized as a major public health threat jeopardizing the care of thousands of patients worldwide. Gram-positive pathogens exhibit an immense genetic repertoire to adapt and develop resistance to virtually all antimicrobials clinically available. As more molecules become available to treat resistant gram-positive infections, resistance emerges as an evolutionary response. Thus, antimicrobial resistance has to be envisaged as an evolving phenomenon that demands constant surveillance and continuous efforts to identify emerging mechanisms of resistance to optimize the use of antibiotics and create strategies to circumvent this problem. Here, we will provide a broad perspective on the clinical aspects of antibiotic resistance in relevant gram-positive pathogens with emphasis on the mechanistic strategies used by these organisms to avoid being killed by commonly used antimicrobial agents.

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.

Methicillin-sensitive Staphylococcus aureus CC398 in intensive care unit, France

During testing for Staphylococcus aureus in an intensive care unit in France in 2011, we found that methicillin-sensitive S. aureus clonal complex 398 was the most frequent clone (29/125, 23.2%). It was isolated from patients (5/89, 5.6%), health care workers (2/63, 3.2%), and environmental sites (15/864,1.7%). Results indicate emergence of this clone in a hospital setting.

A longitudinal assessment of antimicrobial susceptibility among important pathogens collected as part of the Tigecycline Evaluation and Surveillance Trial (T.E.S.T.) in France between 2004 and 2012

BACKGROUND

Clinically important Gram-positive and -negative isolates were collected from patients in France between 2004 and 2012 as a part of the Tigecycline Evaluation and Surveillance Trial.

METHODS

MICs were determined using methodology described by the Clinical and Laboratory Standards Institute.

RESULTS

In total, 17,135 isolates were contributed by 29 medical centres; respiratory (25.1%) and cardiovascular (20.3%) sources predominated. High susceptibility was observed among Enterococcus spp. and Staphylococcus aureus (including methicillin-resistant S. aureus [MRSA]) to linezolid (100%), tigecycline (≥99.8%) and vancomycin (≥94.6%). The percentage of MRSA decreased from 34.3% in 2004 to 20.0% in 2009 before increasing to 34.7% in 2012. Vancomycin, linezolid, levofloxacin and carbapenems were highly active (≥99.6%) against Streptococcus pneumoniae; 3.2% were PRSP. Escherichia coli showed peak susceptibility to the carbapenems (≥99.9%), tigecycline (99.3%) and amikacin (97.9%); significant (p < 0.01) decreases in susceptibility were observed for ampicillin, cefepime and ceftriaxone between 2004 and 2012. ESBL production among E. coli increased from 3.0% (2004) to 14.9% (2012). High susceptibility was noted among Haemophilus influenzae to levofloxacin (100%), amoxicillin-clavulanate (99.2%), carbapenems (≥98.7%) and ceftriaxone (98.5%); β-lactamase production fluctuated with no notable trend between 18.1% (2007) and 27.7% (2011). Klebsiella spp. were highly susceptible to carbapenems (≥99.6%) and amikacin (≥96.4%); significant (p < 0.01) decreases in amoxicillin-clavulanate, cefepime, ceftriaxone, levofloxacin, piperacillin-tazobactam and tigecycline susceptibility were observed among K. pneumoniae between 2004 and 2012. Only imipenem was highly active (96.5% susceptible) against Acinetobacter baumannii. Imipenem and amikacin (87.7% and 87.1% susceptible) were the most active agents against P. aeruginosa; 10.2% of isolates were categorized as multidrug resistant.

CONCLUSIONS

Carbapenems, linezolid, tigecycline and vancomycin conserved good in vitro activity against most pathogens (according to their spectrum of activity) in France between 2004 and 2012.

Methicillin-resistant Staphylococcus aureus: an evolving pathogen

The horizontal transmission of methicillin resistance to Staphylococcus aureus (MRSA) in hospital and community settings, and growing prevalence of these strains, presents a significant clinical challenge to the management of serious infections worldwide. While infection control initiatives have stemmed the rising prevalence, MRSA remains a significant pathogen. More recently, evidence that MRSA is becoming resistant to glycopeptides and newer therapies raises concern about the use of these therapies in clinical practice. Vancomycin resistance has become evident in select clinical settings through rising MICs, growing awareness of heteroresistance, and emergence of intermediate-resistant and fully resistant strains. While resistance to linezolid and daptomycin remains low overall, point mutations leading to resistance have been described for linezolid, and horizontal transmission of cfr-mediated resistance to linezolid has been reported in clinical isolates. These resistance trends for newer therapies highlight the ongoing need for new and more potent antimicrobial therapies.

Atypical pneumonia linked to community-acquired staphylococcus aureus cross-transmission in the nursery

We report the observation of a necrotizing pneumonia due to methicillin-resistant Staphylococcus aureus harboring the Panton-Valentine leukocidin-encoding gene in a previously healthy neonate, with favorable clinical outcome in spite of extensive radiologic lesions. The case was linked to a cluster of 3 neonates colonized by Panton-Valentine leukocidin-producing, methicillin-resistant S. aureus through cross-transmission in the nursery, underlining the need to comply with standard infection control precautions in the maternity ward.

Computational analysis of interactomes: current and future perspectives for bioinformatics approaches to model the host-pathogen interaction space

Bacterial and viral pathogens affect their eukaryotic host partly by interacting with proteins of the host cell. Hence, to investigate infection from a systems' perspective we need to construct complete and accurate host-pathogen protein-protein interaction networks. Because of the paucity of available data and the cost associated with experimental approaches, any construction and analysis of such a network in the near future has to rely on computational predictions. Specifically, this challenge consists of a number of sub-problems: First, prediction of possible pathogen interactors (e.g. effector proteins) is necessary for bacteria and protozoa. Second, the prospective host binding partners have to be determined and finally, the impact on the host cell analyzed. This review gives an overview of current bioinformatics approaches to obtain and understand host-pathogen interactions. As an application example of the methods covered, we predict host-pathogen interactions of Salmonella and discuss the value of these predictions as a prospective for further research.