Eradication or Decolonization of Methicillin-Resistant Staphylococcus aureus Carriage: What Are We Doing and Why Are We Doing It?

Cost-effectiveness of a real-time spatiotemporal mapping surveillance system for meticillin-resistant Staphylococcus aureus prevention

OBJECTIVES

An infection surveillance system based on a hospital's digital twin [4D-Disease Outbreak Surveillance System (4D-DOSS)] is being developed in Singapore. It offers near-real-time infection surveillance and mapping capabilities. This early economic modelling study was conducted, using meticillin-resistant Staphylococcus aureus (MRSA) as the pathogen of interest, to assess the potential cost-effectiveness of 4D-DOSS.

METHODS

A Markov model that simulates the likelihood of MRSA colonization and infection was developed to evaluate the cost-effectiveness of adopting 4D-DOSS for MRSA surveillance from the hospital perspective, compared with current practice. The cycle duration was 1 day, and the model horizon was 30 days. Probabilistic sensitivity analysis was conducted, and the probability of cost-effectiveness was reported. Scenario analyses and a value of information analysis were performed.

RESULTS

In the base-case scenario, with 10-year implementation/maintenance costs of 4D-DOSS of $0, there was 68.6% chance that 4D-DOSS would be cost-effective. In a more pessimistic but plausible scenario where the effectiveness of 4D-DOSS in reducing MRSA transmission was one-quarter of the base-case scenario with 10-year implementation/maintenance costs of $1 million, there was 47.7% chance that adoption of 4D-DOSS would be cost-effective. The value of information analysis showed that uncertainty in MRSA costs made the greatest contribution to model uncertainty.

CONCLUSIONS

This early-stage modelling study revealed the circumstances for which 4D-DOSS is likely to be cost-effective at the current willingness-to-pay threshold, and identified the parameters for which further research will be worthwhile to reduce model uncertainty. Inclusion of other drug-resistant organisms will provide a more thorough assessment of the cost-effectiveness of 4D-DOSS.

Formation of a biofilm matrix network shapes polymicrobial interactions

Staphylococcus aureus colonizes the same ecological niche as many commensals. However, little is known about how such commensals modulate staphylococcal fitness and persistence. Here we report a new mechanism that mediates dynamic interactions between a commensal streptococcus and S. aureus. Commensal Streptococcus parasanguinis significantly increased the staphylococcal biofilm formation in vitro and enhanced its colonization in vivo. A streptococcal biofilm-associated protein BapA1, not fimbriae-associated protein Fap1, is essential for dual-species biofilm formation. On the other side, three staphylococcal virulence determinants responsible for the BapA1-dependent dual-species biofilm formation were identified by screening a staphylococcal transposon mutant library. The corresponding staphylococcal mutants lacked binding to recombinant BapA1 (rBapA1) due to lower amounts of eDNA in their culture supernatants and were defective in biofilm formation with streptococcus. The rBapA1 selectively colocalized with eDNA within the dual-species biofilm and bound to eDNA in vitro, highlighting the contributions of the biofilm matrix formed between streptococcal BapA1 and staphylococcal eDNA to dual-species biofilm formation. These findings have revealed an additional new mechanism through which an interspecies biofilm matrix network mediates polymicrobial interactions.

The Active Surveillance of Staphylococcus aureus using Polymerase Chain Reaction-based Identification Method among Hospitalized-patient of Haji Adam Malik General Hospital, Medan, Indonesia

BACKGROUND: Active surveillance of methicillin-resistant Staphylococcus aureus (MRSA) carriers is associated with the lower incidence of bacteremia and lower mortality rates throughout literature; yet, this important step still remains problematic for developing countries, particularly Indonesia. AIM: The study aimed to demonstrate MRSA colonization rate in Haji Adam Malik Hospital, Medan, Indonesia. MATERIALS AND METHODS: The study enrolled 200 mucocutaneous isolates obtained from hospitalized patients during a 1-year period of study (2018). VITEK-2 system in addition to standard bacterial identification, such as gram staining, latex agglutination test, and hemolysis pattern, was performed to select S. aureus colonies in two different laboratories, Microbiology laboratory of Haji Adam Malik General Hospital and Multidisciplinary Laboratory, Faculty of Medicine, Universitas Sumatera Utara, for polymerase chain reaction (PCR) examination. RESULTS: Based on the VITEK-2 system preliminary identification, there were 80 S. aureus colonies which then underwent PCR examination. Through standard PCR assay, there were 32 bacterial isolates contained the mecA gene and it can be determined MRSA colonization rate of the hospital was 16% with consistent results of standard bacterial identification. CONCLUSIONS: Active surveillance of MRSA carriers is mandatory and urged it as a regular program in a hospital setting to decrease MRSA transmission rate.

Genetic profile mutation rpoB in clinical isolate of rifampicin-resistant Staphylococcus aureus

OBJECTIVES

Staphylococcus aureus is one of the bacteria which causes nosocomial infection. Methicillin-Resistant Staphylococcus Aureus eradication using antibiotics combined with rifampicin has shown good results, whereas, adjuvant rifampicin has long been hypothesized to improve the outcome of S. aureus infection treatment. Resistant-rifampicin S. aureus mutates in rpoB gene at some codons. This study was conducted to identify the mutation of rpoB gene in S. aureus which was resistant toward rifampicin.

METHODS

In this study, isolates collected in the Microbiology Laboratory of Dr. Seotomo Surabaya Hospital during May-September 2019. Then, the dilution method was carried out to determine the minimum inhibition concentration for resistant-rifampicin and dilution to determine the inhibition zone diameter. After that, DNA extraction was carried out from rifampicin-susceptible isolates as a control and resistant-rifampicin isolates followed by identification of rpoB gene mutations by Polymerase Chain Reaction (PCR) and sequencing.

RESULTS

There were nine isolates studied. They were four resistant-rifampicin isolates and four susceptible-rifampicin isolates. In four rifampicin-resistant isolates, the most frequent mutations that occurred was His-481 codon (75%) followed by the Ile-527 codon (25%). Rifampicin-susceptible isolates mutated in Pro-475 and Asn-474 codons. One rifampicin-resistant isolate had two mutations in codons Ile-527 and Asn-474.

CONCLUSIONS

The type of mutation that causes the most rifampicin resistance was a missense mutation. The susceptible-rifampicin isolate experienced silent mutations. There was a relation between the type of missense mutation of rpoB gene and rifampin resistance.

Livestock-Associated Methicillin-Resistant Staphylococcus aureus From Animals and Animal Products in the UK

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is an emerging problem in many parts of the world. Although animal-adapted LA-MRSA has been known for many years, recent reports suggest a possible increasing trend in the zoonotic transmission of LA-MRSA in Europe. Since its emergence in the early 2000's, several investigations have indicated that persons in prolonged, repeated contact with affected livestock are at a higher risk of becoming colonized with LA-MRSA. LA-MRSA monitoring in livestock is voluntary under current EU legislation, and not all member states, including the UK, participate. UK LA-MRSA isolates have been detected through scanning surveillance, where samples are submitted from clinically diseased livestock for diagnostic investigation, and research studies. Surveys conducted on retail beef, pig and poultry meat on sale in the UK have also detected LA-MRSA. Taken together these results suggest that LA-MRSA is present in the UK, possibly at low prevalence level, as suggested by available evidence. In this review, we examine the data available from UK livestock and animal products, and make recommendations for future. We also review the findings from whole genome sequencing (WGS) of the possible lineage of some UK livestock isolates.

Epidemiology of Community-Onset Staphylococcus aureus Bacteremia

Introduction

Staphylococcus aureus bacteremia (SAB) is the second-most common cause of community-onset (CO) bacteremia. The incidence of methicillin-resistant S. aureus (MRSA) has recently decreased across much of the United States, and we seek to describe risk factors for CO-MRSA bacteremia, which will aid emergency providers in their choice of empiric antibiotics.

Methods

This is a retrospective cohort study of all patients with SAB at a 500-bed safety net hospital. The proportion of S. aureus isolates that were MRSA ranged from 32–35% during the study period. Variables of interest included age, comorbid medical conditions, microbiology results, antibiotic administration, duration of bacteremia, duration of hospital admission, suspected source of SAB, and Elixhauser comorbidity score. The primary outcome was to determine risk factors for CO-MRSA bacteremia as compared to methicillin-susceptible S. aureus (MSSA) bacteremia in patients admitted to the hospital through the emergency department.

Results

We identified 135 consecutive patients with CO-SAB. In comparison to those with MSSA bacteremia, patients with MRSA bacteremia were younger (odds ratio [OR] 0.5, 95% confidence interval [CI], 0.4–0.7) with higher Elixhauser comorbidity scores (OR 1.4, 95% CI, 1.1–1.7). Additionally, these patients were more likely to have a history of MRSA infection or colonization (OR 8.9, 95% CI, 2.7–29.7) and intravenous drug use (OR 2.4, 95% CI, 1.0–5.7).

Conclusion

SAB continues to be prevalent in our urban community with CO-MRSA accounting for almost one-third of SAB cases. Previous MRSA colonization was the strongest risk factor for current MRSA infection in this cohort of patients with CO-SAB.

Clinical Utility of Methicillin-Resistant Staphylococcus aureus Nasal Screening for Antimicrobial Stewardship: A Review of Current Literature

Significant clinical and financial consequences are associated with both inadequate and unnecessary exposure to broad-spectrum antibiotics. As such, antimicrobial stewardship programs seek objective, reliable, and cost-effective tests to identify patients at highest or lowest risk for drug-resistant organisms to guide empirical antimicrobial selection. Use of methicillin-resistant Staphylococcus aureus (MRSA) nasal screening to rule out MRSA in lower respiratory tract infections has led to significant reductions in duration of vancomycin therapy. The clinical utility of MRSA nasal screening in other types of infection remains less clear. This review describes the performance of MRSA nasal screening in predicting MRSA infection, highlights practical considerations for use of MRSA nasal screening, and provides guidance for incorporating MRSA nasal screening into clinical practice. With a high negative predictive value when the prevalence of MRSA is low, MRSA nasal screening is a valuable antimicrobial stewardship tool with potential applications beyond lower respiratory tract infections. In appropriately selected patients, negative MRSA nasal screening can prevent initiation or guide discontinuation of anti-MRSA therapy. Antimicrobial stewardship programs should develop institutional guidelines to promote proper use of MRSA nasal screening. Pharmacists are well positioned to assist with education, interpretation, and application of MRSA nasal screening results.

Staphylococcus aureus in the nose and throat of Iowan families

The study objective was to determine the prevalence of Staphylococcus aureus colonisation in the nares and oropharynx of healthy persons and identify any risk factors associated with such S. aureus colonisation. In total 263 participants (177 adults and 86 minors) comprising 95 families were enrolled in a year-long prospective cohort study from one urban and one rural county in eastern Iowa, USA, through local newspaper advertisements and email lists and through the Keokuk Rural Health Study. Potential risk factors including demographic factors, medical history, farming and healthcare exposure were assessed. Among the participants, 25.4% of adults and 36.1% minors carried S. aureus in their nares and 37.9% of adults carried it in their oropharynx. The overall prevalence was 44.1% among adults and 36.1% for minors. Having at least one positive environmental site for S. aureus in the family home was associated with colonisation (prevalence ratio: 1.34, 95% CI: 1.07-1.66). The sensitivity of the oropharyngeal cultures was greater than that of the nares cultures (86.1% compared with 58.2%, respectively). In conclusion, the nares and oropharynx are both important colonisation sites for healthy community members and the presence of S. aureus in the home environment is associated with an increased probability of colonisation.

Intestinal carriage of multidrug-resistant bacteria among healthcare professionals in Germany

Healthcare professionals (HCP) might be at increased risk of acquisition of multidrug-resistant bacteria (MDRB), i.e., methillicin-resistant Staphy l oc occus aureus (MRSA), vancomycin-resistant enterococci (VRE), and multidrug-resistant gram-negative bacteria (MDRGN) and could be an unidentified source of MDRB transmission. The aim of this study was to determine the prevalence as well as risk factors of MDRB colonization among HCP. HCP (n=107) taking part in an antibiotic stewardship program, were voluntarily recruited to perform a rectal swab and to fill in a questionnaire to identify risk factors of MDRB carriage, i.e. being physician, gender, travel abroad within the previous 12 months, vegetarianism, regular consumption of raw meat, contact to domestic animals, household members with contact to livestock, work or fellowship abroad, as well as medical treatment abroad and antibiotic therapy within the previous 12 months. Selective solid media were used to determine the colonization rate with MRSA, VRE and MDRGN. MDRGN were further characterized by molecular analysis of underlying β-lactamases. None of the participants had an intestinal colonization with MRSA or VRE. 3.7% of the participants were colonized with extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae, predominantly bla _CTX-M type. Neither additional flouroquinolone resistance nor carbapenem resistance was detected in any of these isolates. No risk factors were identified to have a significant impact of MDRB carriage among HCP. A colonization rate of 3.7% with ESBL-producing Enterobacteriaceae is of interest, but comparing it to previously published data with similar colonization rates in the healthy population in the same geographic area, it is probably less an occupational risk.

Considerations for antibiotic prophylaxis in head and neck cancer surgery

Peri/post-operative antibiotic prophylaxis (POABP) has become standard practice for preventing surgical site infections (SSI) in head and neck cancer patients undergoing microvascular reconstruction, but few data exist on optimal POABP regimens. Current surgical prophylaxis guideline recommendations fail to account for the complexity of microvascular reconstruction relative to other head and neck procedures, specifically regarding wound classification and antibiotic duration. Selection of POABP spectrum is also controversial, and must balance the choice between too narrow, risking subsequent infection, or too broad, and possible unwanted effects (e.g. antibiotic resistance, Clostridium difficile-associated diarrhea). POABP regimens should retain activity against bacteria expected to colonize the upper respiratory/salivary tracts, which include Gram-positive organisms and facultative anaerobes. However, Gram-negative bacilli also contribute to SSI in this setting. POABP doses should be optimized in order to achieve therapeutic tissue concentrations at the surgical site. Antibiotics targeted towards methicillin-resistant Staphylococcus aureus or Pseudomonas aeruginosa are not warranted for all patients. Prolonged POABP durations have shown no differences in SSI when compared to short POABP durations, but prolonged durations provide unnecessarily antibiotic exposure and risk for adverse effects. Given the lack of standardization behind antibiotic POABP in this setting and the potential for poor patient outcomes, this practice necessitates an additional focus of surgeons and antimicrobial stewardship programs. The purpose of this review is to provide an overview of POABP evidence and discuss pertinent clinical implications of appropriate use.

Optimal control applied to community-acquired methicillin-resistant Staphylococcus aureus in hospitals

Optimal control methods are applied to a deterministic mathematical model to characterize the factors contributing to the replacement of hospital-acquired methicillin-resistant Staphylococcus aureus (HA-MRSA) with community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA), and quantify the effectiveness of three interventions aimed at limiting the spread of CA-MRSA in healthcare settings. Characterizations of the optimal control strategies are established, and numerical simulations are provided to illustrate the results.

Is the Colonisation of Staphylococcus aureus in Pets Associated with Their Close Contact with Owners?

In human beings and animals, staphylococci constitute part of the normal microbial population. Staphylococcus aureus could be classified as an opportunistic pathogen because the bacteria are noted in clinically healthy individuals, but when the immune system becomes compromised, they can also cause a wide range of infections. The objective of this study was to test the hypothesis that cats who are in close contact with their owners are at the greatest risk of being colonised with S. aureus. Two groups of cats were investigated: single, pet (domestic) cats that do not have outdoor access; and a local population of feral cats living in urban areas. The prevalence of S. aureus in domestic cats was 19.17%, while it's prevalence in the feral cat population was only 8.3%; which was statistically significant. Analysis of antibiotic resistance, at the genotypic as well as phenotypic level, showed that S. aureus isolates from pet cats were more likely to harbour antibiotic resistant determinants. The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in households was 10.21%, while in feral cats it was only 1.4%. In conclusion, this study has revealed a correlation between close contact with humans and a higher risk of the cats being colonised with S. aureus and harbouring the antibiotic resistant determinants.

Treatment Failure Outcomes for Emergency Department Patients with Skin and Soft Tissue Infections

Introduction

Skin and soft tissue infections (SSTIs) are commonly evaluated in the emergency department (ED). Our objectives were to identify predictors of SSTI treatment failure within one week post-discharge in patients with cutaneous abscesses, as well as to identify predictors of recurrence within three months in that proportion of participants.

Methods

This was a sub-analysis of a parent study, conducted at two EDs, evaluating a new, nucleic acid amplification test (NAAT) for Staphylococcus aureus in ED patients. Patients ≥18 years receiving incision and drainage (I&D) were eligible. Patient-reported outcome data on improvement of fever, swelling, erythema, drainage, and pain were collected using a structured abstraction form at one week, one month, and three months post ED visit.

Results

We enrolled 272 participants (20 from a feasibility study and 252 in this trial), of which 198 (72.8%) completed one-week follow up. Twenty-seven additional one-week outcomes were obtained through medical record review rather than by the one-week follow-up phone call. One hundred ninety-three (73%) patients completed either the one- or three-month follow up. Most patients recovered from their initial infection within one week, with 10.2% of patients reporting one-week treatment failure. The odds of treatment failure were 66% lower for patients who received antibiotics following I&D at their initial visit. Overall SSTI recurrence rate was 28.0% (95% CI [21.6%–34.4%]) and associated with contact with someone infected with methicillin resistant S. aureus (MRSA), previous SSTI history, or clinician use of wound packing.

Conclusion

Treatment failure was reduced by antibiotic use, whereas SSTI recurrence was associated with prior contact, SSTI, or use of packing.

Seasonal variation of respiratory pathogen colonization in asymptomatic health care professionals: A single-center, cross-sectional, 2-season observational study

BACKGROUND

The purpose of this study was to determine the seasonal variance of potentially pathogenic bacterial and viral organisms in nasopharyngeal specimens obtained from asymptomatic health care professionals (HCPs) during the 2014 winter and summer months.

METHODS

Nasopharyngeal specimens from 100 HCPs were collected from Huntsville Hospital (Huntsville, AL) during the winter and from 100 HCPs during the summer. All subjects were tested for 22 viruses and 19 bacteria using Target Enriched Multiplex Polymerase Chain Reaction. Both seasonal cohorts were composed of students, nurses, physicians, and residents.

RESULTS

Of the 100 HCPs tested during the winter, 34 subjects were colonized with at least 1 bacterium, and 11 tested positive for at least 1 virus. Methicillin-resistant Staphylococcus aureus (MRSA), Moraxella catarrhalis, and coronavirus were the most frequently detected potentially infectious agents. Of the 100 HCPs tested during the summer, 37 tested positive for at least 1 bacterium, and 4 tested positive for a viral agent. The most prevalent bacteria were MRSA and Klebsiella pneumonia.

CONCLUSION

Nasopharyngeal carriage among asymptomatic HCPs was common, but the frequency and presence of potential pathogens varied with each season. Understanding the colonization and infection potential of upper respiratory organisms is important, particularly for viruses. Although asymptomatic HCPs certainly harbor a number of different potentially infectious agents, future studies are needed to determine whether colonized pathogens are transmitted or initiate infection in at-risk patient populations.

Concordance of nasal and diabetic foot ulcer staphylococcal colonization

Nasal carriage of Staphylococcus aureus (SA) is an important risk factor for surgical site infections. The goal of this study was to investigate the concordance between nasal and diabetic foot ulcer (DFU) SA carriage. Seventy-nine subjects with DFUs were assessed for nasal and DFU colonization with SA, including methicillin-resistant SA (MRSA). Twenty-five (31.6%) subjects had nares colonization with SA; 29 (36.7%) had DFU colonization with SA. Seven (8.8%) subjects had nares colonization with MRSA, and 7 (8.8%) had DFU colonization with MRSA. Ulcer duration was associated with MRSA presence (P = 0.01). Sensitivity and specificity of positive nasal SA colonization with positive DFU colonization were 41% and 74%. We found substantial discordance between SA strains colonizing DFU and the nasal cavity. The poor positive predictive values for SA isolation in a DFU based on nasal carriage suggests that SA colonization of a DFU by endogenous SA strains cannot be assumed.

Topical triple-antibiotic ointment as a novel therapeutic choice in wound management and infection prevention: a practical perspective

Triple-antibiotic ointment (TAO) is a safe and effective topical agent for preventing infections in minor skin trauma. The formulation contains neomycin, polymyxin B and bacitracin in a petrolatum base. TAO is active against the most common disease-causing pathogens found in wounds and on the skin and may be an attractive alternative to oral therapy in select circumstances. Resistance to TAO does not develop readily, and safety studies have shown that the risk of allergic sensitivity to TAO is low. Susceptibility profiles of TAO have remained relatively unchanged since its discovery. Prophylaxis or treatment with TAO should be considered as resistant organisms continue to emerge in the community and hospital setting.

Decolonization with Mupirocin and Subsequent Risk of Methicillin-Resistant Staphylococcus aureus Carriage in Veterans Affairs Hospitals

Introduction

Hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) infections remain one of the leading causes of preventable patient mortality in the US. Eradication of MRSA through decolonization could prevent both MRSA infections and transmission; however, there is currently no consensus within the infectious disease community on the proper role of decolonization in the prevention of infections. The purpose of this study was to assess the impact of decolonization with mupirocin on subsequent MRSA carriage.

Methods

Patients included in this study were those with an inpatient admission to a Department of Veterans Affairs (VA) hospital between January 1, 2008 and December 31, 2009 who had a positive MRSA screen on admission and a subsequent re-admission during the same time period. Exposure to mupirocin on the initial hospital admission was measured using Barcode Medication Administration data and MRSA carriage was measured using microbiology text reports and lab data containing results from surveillance swabs collected from the nares. Chi-square tests were used to test for differences in re-admission MRSA carriage rates between mupirocin-receiving and non-mupirocin-receiving patients.

Results

Of the 25,282 MRSA-positive patients with a subsequent re-admission included in the present study cohort, 1,183 (4.7%) received mupirocin during their initial hospitalization. Among the patients in the present study cohort who were re-admitted within 30 days, those who received mupirocin were less likely to test positive for MRSA carriage than those who did not receive mupirocin (27.2% vs. 55.1%, P < 0.001). The proportion of those who tested positive for MRSA during re-admissions that occurred 30–60 days, 60–120 days, and >120 days were 33.9, 37.3, and 41.0%, respectively, among mupirocin patients and 52.7%, 53.0%, and 51.9%, respectively, for patients who did not receive mupirocin (P < 0.001 at each time point).

Conclusion

Patients decolonized with mupirocin in VA hospitals were less likely to be colonized with MRSA on re-admission as long as 4 months after decolonization.

Methicillin-resistant Staphylococcus aureus (MRSA) on the skin of long-term hospitalised horses

Given the significance of methicillin-resistant Staphylococcus aureus (MRSA) infections for both horses and staff in equine veterinary hospitals, protocols are required to minimise the risk of nosocomial transmission, including the screening of the skin and nasal chambers of equine patients for evidence of infection. The objective of this study was to clarify the potential existence and extent of MRSA on the skin of horses requiring long-term hospitalisation (≥ 6 months). Thirty such horses were sampled at eight different locations on their skin and from their nasal chambers. MRSA was isolated from 12 animals (40%), with all sample sites testing positive on at least one occasion. Organisms were most frequently detected in the nasal chambers (relative sensitivity, 83.3%; 34.5% positive horses; isolation rate 33.3%). Skin presence was found in 30% of animals with the highest isolation rates found at the carpus (16.7%), neck, withers and croup (13.3% each). To achieve a relative screening sensitivity of >90%, at least one skin site was required in addition to nasal sampling. This evidence of skin as well as nasal reservoirs of MRSA in long-term hospitalised horses should facilitate the design of effective screening and containment protocols.

Membranous laryngitis in a child

The most common etiologies for acute infectious airway obstruction include epiglottitis, croup, and bacterial tracheitis. We present a unique cause of upper airway obstruction in a child not previously described. To our knowledge this is the first case in the literature of membranous laryngitis in a child due to Methicillin-resistant Staphylococcus Aureus (MRSA). The diagnosis was made by endoscopy and culture and treated with culture directed antibiotics and debridement of membranes from the larynx. The patient did not present with clinical symptoms consistent with epiglottitis as the disease course was not abrupt, and the patient did not present with classic posturing and drooling. Croup-like symptoms were described, but there was no evidence of subglottic involvement radiographically or on endoscopy. Additionally, there was no evidence of membranous plaques within the trachea or subglottis which would be suggestive of bacterial tracheitis. This unique finding is likely the result of MRSA superinfection in a child with Influenza type B.

The use of a critical care consult team to identify risk for methicillin-resistant Staphylococcus aureus infection and the potential for early intervention: a pilot study

OBJECTIVE

To test whether a critical care consult team can be used to identify patients who have methicillin-resistant Staphylococcus aureus nasal colonization during a window period at which they are at highest risk for methicillin-resistant S. aureus infection and can most benefit from topical decolonization strategies.

DESIGN

Prospective cohort study.

SETTING

Two adult tertiary care hospitals.

PATIENTS

Patients with at least one risk factor for methicillin-resistant S. aureus nasal colonization who were seen by a critical care consult team for potential intensive care unit admission were enrolled.

INTERVENTIONS

Nasal cultures for methicillin-resistant S. aureus were performed on all subjects. All subjects were followed for the development of a methicillin-resistant S. aureus infection for 60 days or until hospital discharge. Demographic and outcome data were recorded on all subjects.

MEASUREMENTS AND MAIN RESULTS

Two hundred subjects were enrolled. Overall 29 of 200 (14.5%) were found to have methicillin-resistant S. aureus nasal colonization. Methicillin-resistant S. aureus infections occurred in seven of 29 (24.1%) subjects with methicillin-resistant S. aureus nasal colonization vs. one of 171 (0.6%) subjects without methicillin-resistant S. aureus nasal colonization (p < .001). Methicillin-resistant S. aureus clinical specimens were recovered in 15 of 29 (51.7%) subjects with methicillin-resistant S. aureus nasal colonization vs. two of 171 (1.2%) without methicillin-resistant S. aureus nasal colonization.

CONCLUSIONS

A critical care consult team can be used to rapidly recognize patients with methicillin-resistant S. aureus nasal colonization who are at very elevated risk for methicillin-resistant S. aureus infection. The use of such a team to recognize patients who have greatest potential benefit from decolonization techniques might reduce the burden of severe methicillin-resistant S. aureus infections.

Screening for MRSA

Rapid screening is no more effective at reducing acquisition than conventional screening

The potential of phages to prevent MRSA infections

This short review attempts to examine whether there is a potential for the use of phages capable of infecting Staphylococcus aureus to eradicate or reduce nasal colonisation, thereby reducing the overall infection burden in patient populations identified as being at risk from MRSA infections. There is clear evidence that nasal decolonisation may be of benefit to certain patient groups and also that phages can effectively combat experimentally induced S. aureus infections in animals. However, this is not in itself enough to validate the use of phages for decolonisation and, given the appearance of strains resistant to currently used topical antibiotics, there is a need for clinical trials of this prophylactic use of phages.