Three strategies in the control of staphylococci including methicillin-resistant Staphylococcus aureus

Epidemiology and control of meticillin-resistant Staphylococcus aureus in Stockholm County, Sweden, 2000 to 2016: overview of a "search-and-contain" strategy

To review the epidemiology and measures to control meticillin-resistant Staphylococcus aureus, MRSA, in Stockholm between 2000 and 2016 from the perspective of the Department of Communicable Disease Control and Prevention, Stockholm County Council, Sweden. Age, sex, and place of acquisition of their MRSA on all patients reported to the department were reviewed. Measures for control included surveillance through mandatory reporting of cases, screening patients with risk factors for MRSA, strict adherence to basic nursing hygienic principles, isolation of MRSA positive patients in single rooms in dedicated MRSA wards, and cohorting of staff. An MRSA team was created at the Department of Infectious Diseases, Karolinska University Hospital, for follow-up of all cases. Several administrative meetings and cooperative groups were formed that are still in function. From 2000 to 2016, there were 7373 MRSA cases reported. Healthcare-associated MRSA, HA-MRSA, was successfully controlled, and from 2006 onwards, very limited HA-MRSA transmission or outbreaks occurred. However, incidence increased overall, from 9.5 per 100,000 in 2000 to 37.3 per 100,000 in 2016, due to increase of MRSA acquired abroad and of MRSA acquired in the Swedish community. Surveillance and control measures have been successful in containing HA-MRSA in Stockholm, Sweden, but incidence has increased substantially due to imported cases and spread in the Swedish community. The strategy may be termed "search-and-contain" since screening, infection control, follow-up, and advice on personal hygiene were cornerstones of control, whereas eradication of carriage was not.

Quantifying the transmission dynamics of MRSA in the community and healthcare settings in a low-prevalence country

Methicillin-resistant Staphylococcus aureus (MRSA), traditionally associated with hospitals, is increasingly circulating in the community. This imposes, in turn, a potential burden on hospital infection control due to a more frequent hospitalization of colonized patients. We developed an individual-based model, reproducing community and healthcare settings, to understand the epidemiological drivers of MRSA and the connections between the society and the healthcare institutions. We show that in Norway, a low-prevalence country, the rise of infections is driven by an increasing inflow of cases from abroad rather than by an ongoing epidemic. We demonstrate the major role played by households in transmitting MRSA and show that the burden on hospitals from the growing community circulation is still limited thanks to aggressive infection-control protocols.

Methicillin-resistant Staphylococcus aureus (MRSA) is a primarily nosocomial pathogen that, in recent years, has increasingly spread to the general population. The rising prevalence of MRSA in the community implies more frequent introductions in healthcare settings that could jeopardize the effectiveness of infection-control procedures. To investigate the epidemiological dynamics of MRSA in a low-prevalence country, we developed an individual-based model (IBM) reproducing the population’s sociodemography, explicitly representing households, hospitals, and nursing homes. The model was calibrated to surveillance data from the Norwegian national registry (2008–2015) and to published household prevalence data. We estimated an effective reproductive number of 0.68 (95% CI 0.47–0.90), suggesting that the observed rise in MRSA infections is not due to an ongoing epidemic but driven by more frequent acquisitions abroad. As a result of MRSA importations, an almost twofold increase in the prevalence of carriage was estimated over the study period, in 2015 reaching a value of 0.37% (0.25–0.54%) in the community and 1.11% (0.79–1.59%) in hospitalized patients. Household transmission accounted for half of new MRSA acquisitions, indicating this setting as a potential target for preventive strategies. However, nosocomial acquisition was still the primary source of symptomatic disease, which reinforces the importance of hospital-based transmission control. Although our results indicate little reason for concern about MRSA transmission in low-prevalence settings in the immediate future, the increases in importation and global circulation highlight the need for coordinated initiatives to reduce the spread of antibiotic resistance worldwide.

Control of healthcare- and community-associated MRSA: recent progress and persisting challenges

BACKGROUND

Healthcare adapted meticillin-resistant Staphylococcus aureus (MRSA) has spread to hospitals around the world over 50 years. More recently, other strains of MRSA have emerged with the ability to spread in the community and infect otherwise healthy individuals. Morbidity and mortality associated with MRSA remains high and its control in both the healthcare and community setting has proven challenging.

SOURCES OF DATA

Pubmed (Medline).

AREAS OF AGREEMENT

The use of targeted screening and decolonization, hand hygiene and antimicrobial stewardship is supported by the most robust studies, though many studies have implemented bundles for effective healthcare-associated (HA)-MRSA control.

AREAS OF CONTENTION

Universal screening, universal decolonization and contact precautions for HA-MRSA control are supported by less evidence. Some interventions may not be cost-effective. Contact precautions may be associated with potential for patient harm. Evidence for effective control community acquired (CA)-MRSA is largely lacking.

GROWING POINTS

Programmes that focus on implementing bundles of interventions aimed at targeting HA-MRSA are more likely to be effective, with an emphasis on hand hygiene as a key component. Control of CA-MRSA is likely to be more difficult to achieve and relies on prevalence, risk factors and community healthcare interactions on a broader scale.

AREAS TIMELY FOR DEVELOPING RESEARCH

Further research in the area of CA-MRSA in particular is required. Antimicrobial stewardship for both CA and HA-MRSA is promising, as is the role of whole genome sequencing in characterizing transmission. However, further work is required to assess their long-term roles in controlling MRSA. With many institutions applying widespread use of chlorhexidine washes, monitoring for chlorhexidine resistance is paramount to sustaining efforts at controlling MRSA.

Should We Vigorously Try to Contain and Control Methicillin-Resistant Staphylococcus aureus?

Objective:

To review practices currently used to control transmission of methicillin-resistant Staphylococcus aureus (MRSA) in hospitals, determine the frequency of their use, and discuss the indications for implementing such measures.

Design:

A questionnaire survey to determine how commonly selected control practices are used, and a literature review of the efficacy of control practices.

Participants:

Two hundred fifty-six of 360 hospital-based members fo the Society for Hospital Epidemiology of America, Inc. (SHEA) completed the survey questionnaire.

Result:

Many different combinations of surveillance and control measures are used by hospitals with MRSA. Nine percent of hospitals stated that no special measures were used to control MRSA. The efficacy of commonly used control measures has not been established by controlled trials.

Conclusions:

Implementing control measures is warranted when MRSA causes a high incidence of serious nosocomial infections, and is desirable when MRSA has been newly introduced into a hospital or into an intensive care unit, or when MRSA accounts for more than 10% of nosocomial staphylococcal isolates. While the value of some practices is well established, measures such as routinely attempting to eradicate carriage of MRSA by colonized patients and personnel require further evaluation.

The Control of Methicillin-Resistant Staphylococcus aureus Blood Stream Infections in England

Methicillin-resistant Staphylococcus aureus (MRSA) blood stream infection (BSI) is a major healthcare burden in some but not all healthcare settings, and it is associated with 10%-20% mortality. The introduction of mandatory reporting in England of MRSA BSI in 2001 was followed in 2004 by the setting of target reductions for all National Health Service hospitals. The original national target of a 50% reduction in MRSA BSI was considered by many experts to be unattainable, and yet this goal has been far exceeded (∼80% reduction with rates still declining). The transformation from endemic to sporadic MRSA BSI involved the implementation of serial national infection prevention directives, and the deployment of expert improvement teams in organizations failed to meet their improvement trajectory targets. We describe and appraise the components of the major public health infection prevention campaign that yielded major reductions in MRSA infection. There are important lessons and opportunities for other healthcare systems where MRSA infection remains endemic.

Methicillin-resistant Staphylococcus aureus, Western Australia

Endemic MRSA persists in Western Australia despite control measures.

Methicillin-resistant Staphylococcus aureus (MRSA) continues to be a notable cause of hospital-acquired infections. A statewide screening and control policy was implemented in Western Australia (WA) after an outbreak of epidemic MRSA in a Perth hospital in 1982. We report on statutory notifications from1998 to 2002 and review the 20-year period from 1983 to 2002. The rate of reporting of community-associated Western Australia MRSA (WAMRSA) escalated from 1998 to 2002 but may have peaked in 2001. Several outbreaks were halted, but they resulted in an increase in reports as a result of screening. A notable increase in ciprofloxacin resistance during the study period was observed as a result of more United Kingdom epidemic MRSA (EMRSA) -15 and -16. WA has seen a persistently low incidence of multidrug-resistant MRSA because of the screening and decolonization program. Non–multidrug-resistant, community-associated WAMRSA strains have not established in WA hospitals.

Treatment of bullous impetigo and the staphylococcal scalded skin syndrome in infants

Impetigo is a common, superficial, bacterial infection of the skin characterized by an inflamed and infected epidermis. The rarer variant, bullous impetigo, is characterized by fragile fluid-filled vesicles and flaccid blisters and is invariably caused by pathogenic strains of Staphylococcus aureus. Bullous impetigo is at the mild end of a spectrum of blistering skin diseases caused by a staphylococcal exfoliative toxin that, at the other extreme, is represented by widespread painful blistering and superficial denudation (the staphylococcal scalded skin syndrome). In bullous impetigo, the exfoliative toxins are restricted to the area of infection, and bacteria can be cultured from the blister contents. In staphylococcal scalded skin syndrome the exfoliative toxins are spread hematogenously from a localized source causing widespread epidermal damage at distant sites. Both occur more commonly in children under 5 years of age and particularly in neonates. It is important to swab the skin for bacteriological confirmation and antibiotic sensitivities and, in the case of staphylococcal scalded skin syndrome, to identify the primary focus of infection. Topical therapy should constitute either fusidic acid (Fucidin, Leo Pharma Ltd) as a first-line treatment, or mupirocin (Bactroban, GlaxoSmithKline) in proven cases of bacterial resistance. First-line systemic therapy is oral or intravenous flucloxacillin (Floxapen, GlaxoSmithKline). Nasal swabs from the patient and immediate relatives should be performed to identify asymptomatic nasal carriers of Staphylococcus aureus. In the case of outbreaks on wards and in nurseries, healthcare professionals should also be swabbed.

Isolation measures in the hospital management of methicillin resistant Staphylococcus aureus (MRSA): systematic review of the literature

OBJECTIVE

To evaluate the evidence for the effectiveness of isolation measures in reducing the incidence of methicillin resistant Staphylococcus aureus (MRSA) colonisation and infection in hospital inpatients.

DESIGN

Systematic review of published articles.

DATA SOURCES

Medline, Embase, CINAHL, Cochrane Library, System for Information on Grey Literature in Europe (SIGLE), and citation lists (1966-2000).

REVIEW METHODS

Articles reporting MRSA related outcomes and describing an isolation policy were selected. No quality restrictions were imposed on studies using isolation wards or nurse cohorting. Other studies were included if they were prospective or employed planned comparisons of retrospective data.

RESULTS

46 studies were accepted; 18 used isolation wards, nine used nurse cohorting, and 19 used other isolation policies. Most were interrupted time series, with few planned formal prospective studies. All but one reported multiple interventions. Consideration of potential confounders, measures to prevent bias, and appropriate statistical analysis were mostly lacking. No conclusions could be drawn in a third of studies. Most others provided evidence consistent with a reduction of MRSA acquisition. Six long interrupted time series provided the strongest evidence. Four of these provided evidence that intensive control measures including patient isolation were effective in controlling MRSA. In two others, isolation wards failed to prevent endemic MRSA.

CONCLUSION

Major methodological weaknesses and inadequate reporting in published research mean that many plausible alternative explanations for reductions in MRSA acquisition associated with interventions cannot be excluded. No well designed studies exist that allow the role of isolation measures alone to be assessed. None the less, there is evidence that concerted efforts that include isolation can reduce MRSA even in endemic settings. Current isolation measures recommended in national guidelines should continue to be applied until further research establishes otherwise.

Methicillin-resistant Staphylococcus aureus in hospitals and the community: stealth dynamics and control catastrophes

Methicillin-resistant Staphylococcus aureus (MRSA) represents a serious threat to the health of hospitalized patients. Attempts to reduce the spread of MRSA have largely depended on hospital hygiene and patient isolation. These measures have met with mixed success: although some countries have almost eliminated MRSA or remained largely free of the organism, others have seen substantial increases despite rigorous control policies. We use a mathematical model to show how these increases can be explained by considering both hospital and community reservoirs of MRSA colonization. We show how the timing of the intervention, the level of resource provision, and chance combine to determine whether control measures succeed or fail. We find that even control measures able to repeatedly prevent sustained outbreaks in the short-term can result in long-term control failure resulting from gradual increases in the community reservoir. If resources do not scale with MRSA prevalence, isolation policies can fail "catastrophically."

A pilot study on infection control in 10 randomly selected European hospitals: results of a questionnaire survey

We describe and compare the organization of infection control and some infection control practices in 10 hospitals in seven different European countries. Great differences were observed. By evaluating infection control and hygiene practices in different European centers, areas of prime importance for the development of a European infection control standard may be defined.

Methicillin-resistant Staphylococcus aureus: impact at a national cystic fibrosis centre

In many patient populations there has been a progressive increase in the prevalence of methicillin-resistant Staphylococcus aureus (MRSA). We examined the prevalence and consequences of acquiring MRSA in the adult cystic fibrosis (CF) population at Royal Brompton. Patients who became colonized by MRSA between 1965 and 1997 were identified from an existing database and case-notes were reviewed. Clinical and microbiological data were recorded. Twenty-six patients became colonized with MRSA during this period. Median age at acquisition was 23.4 years (range 11.8-43.3 years) and median FEV1 (percent predicted) was 28.9% (range 12-81%). Twenty patients (77%) had an FEV1 of < or = 40% predicted MRSA was probably acquired by four patients at Royal Brompton. In 17 patients isolates wer first identified whilst under the care of a total of 11 other institutions. Since the first case of MRSA infection in 1982, there has been an increase in prevalence to a current rate of nine cases in the first seven months of 1997. The commonest site of colonization was the lower airway (96%); the nose (23%) and skin sites (15%) were more rarely affected. Duration of colonization was frequently brief with nine cases (35%) lasting less than one month. The identification of MRSA appeared to be of little clinical significance, and did not generally affect outcomes. Only three patients were MRSA positive at the time of death, and in only one of these was MRSA considered a possible contributing factor.

Staphylococcus aureus: a review of the literature

Staphylococcus aureus has a long association with nosocomial infection. Problems date from the 1950s, although methicillin-resistant Staphylococcus aureus (MRSA) did not emerge until the following decade. Initially the pathogenicity of antibiotic-resistant strains was underestimated, and is still sometimes questioned, but today most authorities consider MRSA a serious threat, especially given current preoccupation with cost-effectiveness within the health service: nosocomial infection is associated with increased expenditure and may be regarded as a hallmark of indifferent nursing and medical care. This review documents the emergence of MRSA and recognition of the ensuing problems throughout the 1980s and early 1990s, with suggestions for nursing activities which could contribute towards improved control. Lessons learnt during outbreaks are seen to be of value, but there is also a need for staff at ward level to review routine practice continually so that awareness of activities likely to result in cross-infection is maintained. The use of protective clothing emerges as less important than handwashing, which may be periodically audited to maintain standards.

Nurses' hands as vectors of hospital-acquired infection: a review

Hospital-acquired infections (HAI) are notorious for the manner in which they complicate the course of the original illness, increase costs of hospital stay and delay recovery. This review will briefly outline the problems presented by HAI in developed countries and present evidence that Staphylococcus aureus and gram negative bacilli, the main causative agents, reach susceptible patients via the contact rather than airborne route, predominantly on the hands of hospital staff. Good hand hygiene could help reduce the economic burden and patient distress caused by HAI, but there is evidence that it is infrequently and poorly performed by nurses, the health care staff most frequently in continuous contact with patients. Possible reasons are explored in an attempt to identify strategies to improve hand hygiene.

Control of epidemic methicillin-resistant Staphylococcus aureus in a Dutch university hospital

Between 1986 and 1989 a single strain of a methicillin- and multiply-resistant Staphylococcus aureus caused three distinct outbreaks at Utrecht University Hospital, involving 11, 19 and 32 patients, respectively. In all three episodes, members of staff were screened for MRSA carriage, and 58 persons were found to have positive nose cultures. In each outbreak it became necessary to isolate colonized and infected patients on a separate isolation ward. Staff carriers were also treated. Over the 18 months since the last outbreak, no new acquisitions of this epidemic MRSA strain have occurred. Between 1986 and 1989, the strain which caused the three outbreaks was not the only MRSA strain which was introduced into the hospital. Six other strains, which differed from the epidemic strain as shown by phage typing and antimicrobial susceptibility pattern, were found in single patients. The experience at Utrecht University Hospital illustrates the need for strict measures to eradicate epidemic strains of MRSA as well as the differences in "epidemicity" among various strains of MRSA.

Should we vigorously try to contain and control methicillin-resistant Staphylococcus aureus?

OBJECTIVE

To review practices currently used to control transmission of methicillin-resistant Staphylococcus aureus (MRSA) in hospitals, determine the frequency of their use, and discuss the indications for implementing such measures.

DESIGN

A questionnaire survey to determine how commonly selected control practices are used, and a literature review of the efficacy of control practices.

PARTICIPANTS

Two hundred fifty-six of 360 hospital-based members fo the Society for Hospital Epidemiology of America, Inc. (SHEA) completed the survey questionnaire.

RESULTS

Many different combinations of surveillance and control measures are used by hospitals with MRSA. Nine percent of hospitals stated that no special measures were used to control MRSA. The efficacy of commonly used control measures has not been established by controlled trials.

CONCLUSIONS

Implementing control measures is warranted when MRSA causes a high incidence of serious nosocomial infections, and is desirable when MRSA has been newly introduced into a hospital or into an intensive care unit, or when MRSA accounts for more than 10% of nosocomial staphylococcal isolates. While the value of some practices is well established, measures such as routinely attempting to eradicate carriage of MRSA by colonized patients and personnel require further evaluation.

Outbreaks of infection with methicillin-resistant Staphylococcus aureus on neonatal and burns units of a new hospital

Multiple introductions of methicillin-resistant Staphylococcus aureus (MRSA) strains occurred to a new hospital in Hong Kong. Two years of clinical microbiological surveillance of the resulting outbreaks was combined with laboratory investigation by phage and antibiogram typing, and plasmid profiling. The outbreaks on the special care baby (SCBU) and burns (BU) units were studied in detail, and colonization of staff and contamination of the environment were investigated. MRSA were spread by the hands of staff on the SCBU, where long-term colonization of dermatitis was important, but were probably transmitted on the BU by a combination of the airborne, transient hand-borne and environmental routes. Simple control measures to restrict hand-borne spread on the SCBU were highly effective, but control was not successful on the BU.

Efficacy of short courses of oral novobiocin-rifampin in eradicating carrier state of methicillin-resistant Staphylococcus aureus and in vitro killing studies of clinical isolates

Methicillin-resistant Staphylococcus aureus (MRSA) is an important nosocomial infection problem. Colonization appears to be more common than invasive disease is. Eradication of colonization or the carrier state could limit the spread of MRSA, thus reducing the potential for mortality and morbidity in other patients. The detection of patients with MRSA infection in a rehabilitation ward led to a study of the combination of novobiocin-rifampin in vivo and in vitro. We found that 300 mg of rifampin plus 500 mg of novobiocin orally twice daily for 5 days, in 18 courses of treatment given to 12 patients, resulted in the clearing of MRSA in 79% of the evaluable courses and 81% of the evaluable sites. A second course cleared MRSA from one of the patients with a treatment failure. Side effects were not noted. All 18 pretherapy isolates were susceptible to either drug in vitro, but 1 of 2 posttherapy isolates was rifampin resistant. Timed-kill studies demonstrated that the rate of killing was the same with either drug alone or both drugs together. Pretherapy isolates from treatment successes or failure were killed at the same rate by the drug combination. However, with the rifampin-resistant isolate killing ceased after 48 h. Results of this study suggest that previously untreated patients are likely to have isolates that are susceptible to the combination of drugs and that the combination is commonly effective in eradicating MRSA carriage. Since the regimen is orally administered, and thus convenient, in conjunction with other measures it has the promise of reducing the spread of MRSA in hospitals.