Frequent use of chlorhexidine-based body wash associated with a reduction in methicillin-resistant Staphylococcus aureus nasal colonization among military trainees

Infection prevention-how can we prevent transmission of community-onset methicillin-resistant Staphylococcus aureus?

BACKGROUND

Staphylococcus aureus is a versatile organism, capable of existing as a commensal organism while also possessing pathogenic potential. The emergence of clinically and genetically distinct strains of methicillin-resistant S. aureus (MRSA), termed community-onset MRSA (CO-MRSA), resulted in an epidemic of invasive and skin and soft tissue infections (SSTI) in otherwise healthy individuals without traditional risk factors. Colonization with S. aureus is a risk factor for developing infection and also a source of transmission to close contacts. Outbreaks of S. aureus SSTI have been described in crowded settings and within households. Thus, preventive strategies are essential to interrupt recurrent infections.

OBJECTIVES

The objective of this narrative review is to provide a comprehensive, evidence-based approach to prevent transmission of CO-MRSA. We highlight key clinical trials that emphasize the importance of household and environmental S. aureus colonization in propagating household transmission. Finally, we highlight research priorities to prevent S. aureus infection.

SOURCES

We cite primary literature from peer-reviewed publications as sources for this review.

CONTENT

Our recommended approach to the management of individuals presenting with skin abscesses includes optimal treatment of the initial infection and hygiene education. Decolonization measures should be recommended for individuals with recurrent SSTIs or whose household members have SSTIs. Targeted decolonization with topical antimicrobials should be prescribed to all affected individuals within the household.

IMPLICATIONS

S. aureus infections result in substantial mortality and morbidity because of the high incidence of recurrent skin infections. Although current decolonization strategies are beneficial, interventions are often costly to families and effectiveness wanes over time. Results from a recently completed trial evaluating integrated periodic decolonization and household environmental hygiene will further add to our understanding of what constitutes a sustainable decolonization approach. In addition, novel preventive strategies are being developed such as S. aureus vaccines, lytic agents, probiotics, microbiota transplants, and phage therapy.

Safety, immunogenicity, and efficacy of NDV-3A against Staphylococcus aureus colonization: A phase 2 vaccine trial among US Army Infantry trainees

BACKGROUND

Military trainees are at increased risk for Staphylococcus aureus colonization and infection. Disease prevention strategies are needed, but a S. aureus vaccine does not currently exist.

METHODS

We enrolled US Army Infantry trainees (Fort Benning, GA) in a phase 2, randomized, double-blind, placebo-controlled trial of NDV-3A, a vaccine containing a recombinant adhesin/invasion protein of Candida albicans that has structural similarity to the S. aureus protein clumping factor A. Study participants received one intramuscular dose of NDV-3A or placebo (adjuvant alone) within 72 h of arrival on base. Longitudinal nasal and oral (throat) swabs were collected throughout the 14-week Infantry training cycle. Safety, immunogenicity, and efficacy of NDV-3A against S. aureus nasal / oral acquisition were the endpoints.

RESULTS

The NDV-3A candidate had minimal reactogenicity and elicited robust antigen-specific B- and T-cell responses. During the 56-day post-vaccination period, there was no difference in the incidence of S. aureus nasal acquisition between those who were randomized to receive NDV-3A vs. placebo (25.6% vs. 29.1%; vaccine efficacy [VE]: 12.1%; p = 0.31). In time-to-event analysis, there was no difference between study groups with respect to the S. aureus colonization-free interval (VE: 13%; p = 0.29). Similarly, the efficacy of NDV-3A against S. aureus oral acquisition was poor (VE: 2.4%; p = 0.52).

CONCLUSIONS

A single dose of NDV-3A did not prevent nasal nor oral acquisition of S. aureus in a population of military trainees at high risk for colonization.

Opportunities and Obstacles in the Prevention of Skin and Soft-Tissue Infections Among Military Personnel

INTRODUCTION

Skin and soft-tissue infections (SSTIs) are an important cause of infectious disease morbidity among military populations. Due to the high direct and indirect costs associated with SSTIs, particularly with methicillin-resistant Staphylococcus aureus (MRSA) infections, there remains a critical need for the development and evaluation of SSTI prevention strategies among high-risk military personnel. Herein, we review efforts of the Infectious Disease Clinical Research Program (IDCRP) related to the prevention of SSTIs in the military.

METHODS

The IDCRP of the Uniformed Services University has conducted clinical research protocols on SSTI epidemiology and prevention among military personnel since 2009. Observational studies have examined the epidemiology of Staphylococcus aureus colonization and SSTI in training and deployment settings. Two randomized controlled trials of personal hygiene strategies for SSTI prevention at Marine Corps Base Quantico (Virginia) and Fort Benning (Georgia) were performed. Lastly, two vaccine trials have been conducted by the IDCRP, including a Phase 2 S. aureus vaccine trial (currently ongoing) among military trainees.

RESULTS

Military recruits and deployed personnel experience an intense and prolonged exposure to S. aureus, the major causative agent of SSTI. The burden of S. aureus colonization and SSTI is particularly high in military trainees. Hygiene-based trials for S. aureus decolonization among military trainees were not effective in reducing rates of SSTI. In January 2018, the IDCRP initiated a Phase 2 S. aureus vaccine trial among the US Army Infantry training population at Fort Benning.

CONCLUSIONS

In the military, a disproportionate burden of SSTIs is borne by the recruit population. Strategies relying upon routine application of agents for S. aureus decolonization have not been effective in preventing SSTIs. A novel S. aureus vaccine candidate is being currently evaluated in a military training population and may represent a new opportunity to prevent SSTIs for the military.

Prevalence, Characterization, and Drug Resistance of Staphylococcus Aureus in Feces From Pediatric Patients in Guangzhou, China

Background: Staphylococcus aureus (S. aureus) is a major pathogen of human infections. Its fecal carriage serves as a risk factor for nosocomial transmission and disease development. However, the rate of S. aureus fecal carriage among Chinese children has not yet been reported. Therefore, we sought to investigate the prevalence, characterization, and drug resistance of S. aureus isolated from pediatric patients' feces in Southern China. Methods: Fecal samples (2059) from pediatric patients in three centers in Guangzhou were cultured. From which, 412 S. aureus isolates were identified via selective mediums and automated VITEK Mass Spectrometer analysis. Antibiotic susceptibility was determined and DNA sequencing of seven housekeeping genes were used for multilocus sequence typing analysis. Results: The fecal carriage rates were 20.0% for S. aureus and 4.5% for methicillin-resistant S. aureus (MRSA). Moreover, S. aureus fecal carriage was positively correlated with outpatient status and gastroenteritis diagnosis. Moreover, age-related patterns were observed with respect to prevalence of S. aureus. Besides, a total of 76 sequence types (STs) were identified, including 25 newly assigned STs and 28 clonal complexes (CCs). ST188, ST6, and ST15 were the most prevalent methicillin-sensitive S. aureus (MSSA) clones, while ST59 and ST45 were the major MRSA clones. S. aureus isolates also exhibited high rates of penicillin (84.2%), erythromycin (38.8%), and clindamycin (35.9%) resistance. Specifically, all ST30 and ST338 isolates were resistant to erythromycin and clindamycin, 61% of ST7 were resistant to tetracycline, and 84% of ST45 exhibited resistance and intermediate resistance to rifampicin. Also, CC59 (ST338 and ST59) and CC45 exhibited different antibiotic resistance patterns. Conclusion: These results demonstrate the colonization dynamics and molecular epidemiology of S. aureus in child feces in Southern China. Further, they suggest an urgency for strengthening the surveillance programs in China and provide important information for the prevention and treatment of S. aureus infection.

Decolonization of Staphylococcus aureus in Healthcare: A Dermatology Perspective

The bacterium Staphylococcus aureus is responsible for significant morbidity, mortality, and financial burden in healthcare. It easily colonizes susceptible patients and can cause recurrent infections, especially in populations at risk. In addition to treating sequelae of infections, there is a growing body of literature aimed at decolonizing susceptible patients in order to prevent infection and also to prevent spread. Such strategies are widely employed in surgical, intensive care, and hospitalist fields. Staphylococcus aureus involvement has been implicated in the pathogenesis and persistence of many dermatologic diseases that are treated in the outpatient setting. This review serves to summarize current evidence for the management of Staphylococcus aureus colonized patients, as well as the evidence available for decolonization. We further characterize the role that colonization may play in atopic dermatitis, recurrent infections, hand eczema, cutaneous T-cell lymphoma, and also in surgical infections after Mohs surgery.

USA300 Staphylococcus aureus persists on multiple body sites following an infection

BACKGROUND

USA300 methicillin-resistant Staphylococcus aureus (MRSA) is a community- and hospital-acquired pathogen that frequently causes infections but also can survive on the human body asymptomatically as a part of the normal microbiota. We devised a comparative genomic strategy to track colonizing USA300 at different body sites after an initial infection. We sampled ST8 S. aureus from subjects at the site of a first known MRSA infection. Within 60 days of this infection and again 12 months later, each subject was tested for asymptomatic colonization in the nose, throat and perirectal region. 93 S. aureus strains underwent whole genome shotgun sequencing.

RESULTS

Among 28 subjects at the initial sampling time, we isolated S. aureus from the nose, throat and perirectal sites from 15, 11 and 15 of them, respectively. Twelve months later we isolated S. aureus from 9 subjects, with 6, 3 and 3 strains from the nose, throat and perirectal area, respectively. Genome sequencing revealed that 23 patients (ages 0-66 years) carried USA300 intra-subject lineages (ISLs), defined as having an index infection isolate and closely related colonizing strains. Pairwise distance between strains in different ISLs was 48 to 162 single nucleotide polymorphisms (SNPs) across the core regions of the chromosome, whereas within the same ISL it was 0 to 26 SNPs. Strains in ISLs from the same subject differed in plasmid and prophage content, and contained deletions that removed the mecA-containing SCCmec and ACME regions. Five strains contained frameshift mutations in agr toxin-regulating genes. Persistence of an ISL was not associated with clinical or demographic subject characteristics. We inferred that colonization with the ISL occurred about 18 weeks before the first assessment of asymptomatic colonization.

CONCLUSIONS

Clonal lineages of USA300 may continue to colonize people at one or more anatomic sites up to a year after an initial infection and experience loss of the SCCmec, loss and gain of other mobile genetic elements, and mutations in the agr operon.

Chlorhexidine-based body washing for colonization and infection of methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus: an updated meta-analysis

Background

The effects of chlorhexidine-based body washing (CHW) on health care-associated infections have been reported in numerous studies, while their findings remain conflicting. This study aims to update the evidence for the effects of CHW on the risk of colonization or infection with hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE).

Methods

Two independent authors searched PubMed, Embase, and Cochrane Library from inception through February 2018. We selected all observational studies or clinical trials for the effect of CHW on the risk of colonization and infection with hospital-acquired MRSA or VRE. Random-effects models were applied to calculate summary incidence rate ratios (IRRs) for the related associations.

Results

Of 140 records identified, we obtained data from 17 relevant articles for meta-analysis. Compared with patients without antiseptic bathing, patients with CHW had a significantly lower risk of MRSA colonization (IRR 0.61, 95% CI 0.48–0.77) and VRE colonization (IRR 0.58, 95% CI 0.42–0.80). Similarly, we also noted that patients with CHW had a significantly lower risk of MRSA infection (IRR 0.65, 95% CI 0.52–0.81). However, no significantly lower risk of VRE infection (IRR 0.61, 95% CI 0.30–1.25) was noted in patients with CHW. Sensitivity analyses or trim-and-fill method confirmed the robustness of the findings.

Conclusion

Current evidence supports that patients with CHW had a significantly lower risk of MRSA or VRE colonization and a lower risk of MRSA infection. More evidence should be accumulated to reinforce these findings, especially on the effect of CHW on the risk of VRE infection.

Staphylococcus aureus colonization during military service: a prospective cohort study

OBJECTIVES

Staphylococcus aureus colonization leading to skin and soft-tissue infections (SSTI) are known challenges in crowded settings such as the military. The aim of the study was to establish and compare the prevalence of S. aureus colonization in recruits at enrolment and discharge after the first year of military service, and to investigate the prevalence of S. aureus SSTI.

METHODS

All recruits entering first year of military service in January 2013 to be stationed at three garrisons in the northern part of Norway were invited to join this prospective cohort study. Swabs were taken from nose, throat and perineum. Staphylococcus aureus was identified using standard culturing methods. Methicillin resistance was determined by a cefoxitin disc diffusion test.

RESULTS

Of the 923 eligible recruits, 512 were included at enrolment; 265/512 (52%) were also screened at discharge. Staphylococcus aureus colonization was high, and increased significantly during military service (166/265 versus 224/265, p < 0.001) mainly caused by increase in throat colonization alone or in combination with nasal colonization. All S. aureus isolates were susceptible to methicillin. SSTI was self-reported in 7/265 (3%) recruits, of which only one was confirmed by a military physician.

CONCLUSION

Staphylococcus aureus colonization increased during military service, but there were few confirmed reports of SSTI. Inclusion of throat swab provides important information as ∼20% of the recruits were only positive in their throat. Further analyses need to be performed to investigate if the increase in colonization is caused by specific S. aureus stains.

Routine chlorhexidine gluconate use onboard navy surface vessels to reduce infection: A cluster randomized controlled trial

BACKGROUND

Hand disinfection with chlorhexidine gluconate (CHG) is commonly used for preventing the spread of infection in medical institutions and the community, but studies on its use in military settings have been inconclusive. We examined the effects of CHG on morbidity in Israeli Navy ships.

METHODS

This was a controlled, cluster randomized study that took place at a major naval base in Israel. Ships were randomly selected into the study (347 sailors) and primary control (350 sailors) groups. Additional nonintervention control groups included other sailors serving on the base (n = 360) and logistics and support personnel (n = 859). CHG disinfection devices were installed on all ships in the study group, alongside soap and water. Morbidity was analyzed using a computerized patient record, subjective self-report questionnaires, and a sample of hand cultures. Compliance with hand hygiene was analyzed using a self-report hygiene attitudes questionnaire at the beginning of the trial and after 3 months. The study took place between May and September 2014.

RESULTS

No significant differences were found between the groups in terms of sick days or light-duty days or in the number of acute gastrointestinal or respiratory cases. Sailors were found to have more skin infections than controls, but this was not significantly reduced by CHG. Hand cultures demonstrated that continuous use of CHG did not cause a reduction in colonization. There were no statistically significant differences in self-reported hygiene practices.

CONCLUSIONS

CHG did not demonstrate any medical benefit over the use of soap and water onboard Israeli Navy ships.

High Perineal and Overall Frequency of Staphylococcus aureus in People Who Inject Drugs, Compared to Non-Injectors

To investigate the prevalence, distribution, and colonization burden of Staphylococcus aureus (S. aureus) and MRSA in different body sites among people who inject drugs (PWID) and compare it to a control group consisting of non-injectors. In this cross-sectional survey, 49 active PWID from the needle exchange program (NEP) in Malmö, Sweden, and 60 non-injecting controls from an emergency psychiatric inpatient ward at Malmö Addiction Centre were tested for S. aureus (including MRSA) by culture, PCR, and MALDI-TOF. Samples were taken from anterior nares, throat, perineum, and skin lesions if present. Sixty-seven percent of the PWID were colonized with S. aureus, compared to 50% of the controls (P = 0.08). Perineal carriage was significantly more frequent among PWID than in the control group [37 vs 17%, OR 2.96 (95% CI 1.13-7.75), P = 0.03], also after adjusting for sex and age in multivariate analysis [OR 4.01 (95% CI 1.34-12.03)]. Only one individual in the whole cohort (NEP participant) tested positive for MRSA. PWID may be more frequently colonized with S. aureus in the perineum than non-injection drug users, and there was a trend indicating more frequent overall S. aureus colonization in PWID, as well as higher perineal colonization burden. No indication of a high MRSA prevalence among PWID in Sweden was noted. However, further MRSA prevalence studies among PWID are needed. Knowledge about S. aureus colonization is important for the prevention of S. aureus infections with high morbidity in PWID.