Impacts of a long-term programme of active surveillance and chlorhexidine baths on the clinical and molecular epidemiology of meticillin-resistant Staphylococcus aureus (MRSA) in an Intensive Care Unit in Scotland

Inhibition of the ULK1 protein complex suppresses Staphylococcus-induced autophagy and cell death

Autophagy plays multiple roles in host cells challenged with extracellular pathogens. Here, we aimed to explore whether autophagy inhibition could prevent bacterial infections. We first confirmed widely distinct patterns of autophagy responses in host cells infected with Staphylococcus aureus, as compared with Salmonella Only infection with Staphylococcus produced strong accumulation of lipidated autophagy-related protein LC3B (LC3B-II). Infection with virulent Staphylococcus strains induced formation of p62-positive aggregates, suggestive of accumulated ubiquitinated targets. During Salmonella infection, bacteria remain enclosed by lysosomal-associated membrane protein 2 (LAMP2)-positive lysosomes, whereas virulent Staphylococcus apparently exited from enlarged lysosomes and invaded the cytoplasm. Surprisingly, Staphylococcus appeared to escape from the lysosome without generation of membrane-damage signals as detected by galectin-3 recruitment. In contrast, Salmonella infection produced high levels of lysosomal damage, consistent with a downstream antibacterial xenophagy response. Finally, we studied the Unc-51-like autophagy-activating kinase 1 (ULK1) regulatory complex, including the essential subunit autophagy-related protein 13 (ATG13). Infection of cells with either Staphylococcus or Salmonella led to recruitment of ATG13 to sites of cytosolic bacterial cells to promote autophagosome formation. Of note, genetic targeting of ATG13 suppressed autophagy and the ability of Staphylococcus to infect and kill host cells. Two different ULK1 inhibitors also prevented Staphylococcus intracellular replication and host cell death. Interestingly, inhibition of the ULK1 pathway had the opposite effect on Salmonella, sensitizing cells to the infection. Our results suggest that ULK1 inhibitors may offer a potential strategy to impede cellular infection by S. aureus.

Distribution of the Most Prevalent Spa Types among Clinical Isolates of Methicillin-Resistant and -Susceptible Staphylococcus aureus around the World: A Review

Background:Staphylococcus aureus, a leading cause of community-acquired and nosocomial infections, remains a major health problem worldwide. Molecular typing methods, such as spa typing, are vital for the control and, when typing can be made more timely, prevention of S. aureus spread around healthcare settings. The current study aims to review the literature to report the most common clinical spa types around the world, which is important for epidemiological surveys and nosocomial infection control policies.

Methods: A search via PubMed, Google Scholar, Web of Science, Embase, the Cochrane library, and Scopus was conducted for original articles reporting the most prevalent spa types among S. aureus isolates. The search terms were “Staphylococcus aureus, spa typing.”

Results: The most prevalent spa types were t032, t008 and t002 in Europe; t037 and t002 in Asia; t008, t002, and t242 in America; t037, t084, and t064 in Africa; and t020 in Australia. In Europe, all the isolates related to spa type t032 were MRSA. In addition, spa type t037 in Africa and t037and t437 in Australia also consisted exclusively of MRSA isolates. Given the fact that more than 95% of the papers we studied originated in the past decade there was no option to study the dynamics of regional clone emergence.

Conclusion: This review documents the presence of the most prevalent spa types in countries, continents and worldwide and shows big local differences in clonal distribution.

Chlorhexidine gluconate bathing to reduce methicillin-resistant Staphylococcus aureus acquisition

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is a virulent organism causing substantial morbidity and mortality in intensive care units. Chlorhexidine gluconate, a topical antiseptic solution, is effective against a wide spectrum of gram-positive and gram-negative bacteria, including MRSA. Objectives To examine the impact of a bathing protocol using chlorhexidine gluconate and bath basin management on MRSA acquisition in 5 adult intensive care units and to examine the cost differences between chlorhexidine bathing by using the bath-basin method versus using prepackaged chlorhexidine-impregnated washcloths.

METHODS

The protocol used a 4-oz bottle of 4% chlorhexidine gluconate soap in a bath basin of warm water. Patients in 3 intensive care units underwent active surveillance for MRSA acquisition; patients in 2 other units were monitored for a new positive culture for MRSA at any site 48 hours after admission.

RESULTS

Before the protocol, 132 patients acquired MRSA in 34333 patient days (rate ratio, 3.84). Afterwards, 109 patients acquired MRSA in 41376 patient days (rate ratio, 2.63). The rate ratio difference is 1.46 (95% CI, 1.12-1.90; P = .003). The chlorhexidine soap and bath basin method cost $3.18 as compared with $5.52 for chlorhexidine-impregnated wipes (74% higher).

CONCLUSIONS

The chlorhexidine bathing protocol is easy to implement, cost-effective, and led to decreased unit-acquired MRSA rates in a variety of adult intensive care units.

Efficacy of chlorhexidine bathing for reducing healthcare associated bloodstream infections: a meta-analysis

Background

We performed a meta-analysis of randomized controlled trials (RCTs) to determine if daily bathing with chlorhexidine decreased hospital-acquired BSIs in critically ill patients.

Methods

We searched the MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials databases to identify randomized controlled trials that compared daily bathing with chlorhexidine and a control in critically ill patients.

Results

This meta-analysis included five RCTs. The overall incidence of measured hospital-acquired BSIs was significantly lower in the chlorhexidine group compared to the controls 0.69 (95 % CI 0.55–0.85; P < 0.001; I² = 57.7 %). Gram-positive-induced (RR = 0.49, 95 % CI 0.41–0.58; P = 0.000; I² = 0.0 %) bacteremias were significantly less common in the chlorhexidine group. The incidence of MRSA bacteremias (RR 0.63; 95 % CI 0.44–0.91; P = 0.006; I² = 30.3 %) was significantly lower among patients who received mupirocin in addition to chlorhexidine bathing than among those who did not routinely receive mupirocin.

Conclusions

Daily bathing with chlorhexidine may be effective to reduce the incidence of hospital-acquired BSIs. However, chlorhexidine bathing alone may be of limited utility in reduction of MRSA bacteremia; intranasal mupirocin may also be required. This meta-analysis has several limitations. Future large-scale international multicenter studies are needed.

Turning the tide or riding the waves? Impacts of antibiotic stewardship and infection control on MRSA strain dynamics in a Scottish region over 16 years: non-linear time series analysis

OBJECTIVES

To explore temporal associations between planned antibiotic stewardship and infection control interventions and the molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA).

DESIGN

Retrospective ecological study and time-series analysis integrating typing data from the Scottish MRSA reference laboratory.

SETTING

Regional hospital and primary care in a Scottish Health Board.

PARTICIPANTS

General adult (N=1,051,993) or intensive care (18,235) admissions and primary care registrations (460,000 inhabitants) between January 1997 and December 2012.

INTERVENTIONS

Hand-hygiene campaign; MRSA admission screening; antibiotic stewardship limiting use of macrolides and '4Cs' (cephalosporins, coamoxiclav, clindamycin and fluoroquinolones).

OUTCOME MEASURES

Prevalence density of MRSA clonal complexes CC22, CC30 and CC5/Other in hospital (isolates/1000 occupied bed days, OBDs) and community (isolates/10,000 inhabitant-days).

RESULTS

67% of all clinical MRSA isolates (10,707/15,947) were typed. Regional MRSA population structure was dominated by hospital epidemic strains CC30, CC22 and CC45. Following declines in overall MRSA prevalence density, CC5 and other strains of community origin became increasingly important. Reductions in use of '4Cs' and macrolides anticipated declines in sublineages with higher levels of associated resistances. In multivariate time-series models (R(2)=0.63-0.94) introduction of the hand-hygiene campaign, reductions in mean length of stay (when >4 days) and bed occupancy (when >74 to 78%) predicted declines in CC22 and CC30, but not CC5/other strains. Lower importation pressures, expanded MRSA admission screening, and reductions in macrolide and third generation cephalosporin use (thresholds for association: 135-141, and 48-81 defined daily doses/1000 OBDs, respectively) were followed by declines in all clonal complexes. Strain-specific associations with fluoroquinolones and clindamycin reflected resistance phenotypes of clonal complexes.

CONCLUSIONS

Infection control measures and changes in population antibiotic use were important predictors of MRSA strain dynamics in our region. Strategies to control MRSA should consider thresholds for effects and strain-specific impacts.

Horizontal infection control strategy decreases methicillin-resistant Staphylococcus aureus infection and eliminates bacteremia in a surgical ICU without active surveillance

OBJECTIVE

Methicillin-resistant Staphylococcus aureus infection is a significant contributor to morbidity and mortality in hospitalized patients worldwide. Numerous healthcare bodies in Europe and the United States have championed active surveillance per the "search and destroy" model. However, this strategy is associated with significant economic, logistical, and patient costs without any impact on other hospital-acquired pathogens. We evaluated whether horizontal infection control strategies could decrease the prevalence of methicillin-resistant S. aureus infection in the ICU, without the need for active surveillance.

DESIGN AND SETTING

Retrospective, observational study in the surgical ICU of a tertiary care medical center in Boston, MA, from 2005 to 2012.

PATIENTS

A total of 6,697 patients in the surgical ICU.

INTERVENTIONS

Evidence-based infection prevention strategies were implemented in an iterative fashion, including 1) hand hygiene program with refresher education campaign, 2) chlorhexidine oral hygiene program, 3) chlorhexidine bathing, 4) catheter-associated bloodstream infection program, and 5) daily goals sheets.

MEASUREMENTS AND MAIN RESULTS

The prevalence of methicillin-resistant S. aureus infection fell from 2.66 to 0.69 per 1,000 patient days from 2005 to 2012, an average decrease of 21% per year. The biggest decline in rate of infection was detected in 2008, which may suggest that the catheter-associated bloodstream infection prevention program was particularly effective. Among 4,478 surgical ICU admissions over the last 5 years, not a single case of methicillin-resistant S. aureus bacteremia was observed.

CONCLUSIONS

Aggressive multifaceted horizontal infection control is an effective strategy for reducing the prevalence of methicillin-resistant S. aureus infection and eliminating methicillin-resistant S. aureus bacteremia in the ICU without the need for active surveillance and decontamination.

Chlorhexidine bathing in a tertiary care neonatal intensive care unit: impact on central line-associated bloodstream infections

BACKGROUND

Despite implementation of recommended best practices, our central line-associated bloodstream infection (CLABSI) rates remained high. Our objective was to describe the impact of chlorhexidine gluconate (CHG) bathing on CLABSI rates in neonates.

METHODS

Infants with a central venous catheter (CVC) admitted to the neonatal intensive care unit from April 2009 to March 2013 were included. Neonates with a birth weight of 1,000 g or less, aged less than 28 days, and those with a birth weight greater than 1,000 g were bathed with mild soap until March 31, 2012 (baseline), and with a 2% CHG-impregnated cloth starting on April 1, 2012 (intervention). Infants with a birth weight of 1,000 g or less, aged 28 days or more, were bathed with mild soap during the entire period. Neonatal intensive care unit nurses reported adverse events. Adjusted incidence rate ratios (aIRRs), using Poisson regression, were calculated to compare CLABSIs/1,000 CVC-days during the baseline and intervention periods.

RESULTS

Overall, 790 neonates with CVCs were included in the study. CLABSI rates decreased during the intervention period for CHG-bathed neonates (6.00 vs 1.92/1,000 CVC-days; aIRR, 0.33 [95% confidence interval (CI), 0.15-0.73]) but remained unchanged for neonates with a birth rate of 1,000 g or less and aged less than 28 days who were not eligible for CHG bathing (8.57 vs 8.62/1,000 CVC-days; aIRR, 0.86 [95% CI, 0.17-4.44]). Overall, 195 infants with a birth weight greater than 1,000 g and 24 infants with a birth weight of 1,000 g or less, aged 28 days or more, were bathed with CHG. There was no reported adverse event.

CONCLUSIONS

We observed a decrease in CLABSI rates in CHG-bathed neonates in the absence of observed adverse events. CHG bathing should be considered if CLABSI rates remain high, despite the implementation of other recommended measures.

Controlling hospital MRSA

Recent evidence from publications describing the success of interventions to control hospital meticillin-resistant Staphylococcus aureus (MRSA), often in the endemic setting, is reviewed. Overall, there is cautious ground for optimism that MRSA can be controlled in a cost-effective manner by employing a bundle approach, the mainstay of which is widespread admission screening to inform patient-specific control measures.