Methicillin-resistant Staphylococcus aureus in an Australian teaching hospital

The role of healthcare personnel in the maintenance and spread of methicillin-resistant Staphylococcus aureus

Healthcare workers may acquire methicillin-resistant Staphylococcus aureus (MRSA) from patients, both hospital and home environments, other healthcare workers, family and public acquaintances, and pets. There is a consensus of case reports and series which now strongly support the role for MRSA-carrying healthcare personnel to serve as a reservoir and as a vehicle of spread within healthcare settings. Carriage may occur at a number of body sites and for short, intermediate, and long terms. A number of approaches have been taken to interrupt the linkage of staff-patient spread, but most emphasis has been placed on handwashing and the treatment of staff MRSA carriers. The importance of healthcare workers in transmission has been viewed with varying degrees of interest, and several logistical problems have arisen when healthcare worker screening is brought to the forefront. There is now considerable support for the screening and treatment of healthcare workers, but it is suggested that the intensity of any such approach must consider available resources, the nature of the outbreak, and the strength of epidemiological associations. The task of assessing healthcare personnel carriage in any context should be shaped with due regard to national and international guidelines, should be honed and practiced according to local needs and experience, and must be patient-oriented.

Control of endemic MRSA-what is the evidence? A personal view

Although there is extensive literature on the control of MRSA, when that concerning epidemics is excluded, only a limited amount remains regarding the control of endemic MRSA. Several guidelines have been recently published recommending stringent control measures, which are often suggested based on their success in controlling MRSA outbreaks in hospitals with few MRSA or in containing MRSA cases introduced into a hospital with no MRSA. In these settings, multiple measures are usually introduced with apparently successful results. However, results may not be generalizable to other settings and we do not know the minimum effective measures required for MRSA containment. This paper aims critically to review the literature to determine whether evidence exists for the value of the infection control measures that are widely recommended in the endemic setting. Much of this literature is based on observational studies, with few randomized, controlled trials having been conducted. More well-designed studies are required before many of the principles on which we build infection control programmes can be regarded as evidence based.

Methicillin-resistant Staphylococcus aureus in orthopaedic surgery

We prospectively studied the incidence of methicillin-resistant Staphylococcus aureus (MRSA) colonisation and infection, the patterns and types of operation associated with MRSA acquisition in an orthopaedic and trauma unit in London, UK. Over the 12-month study period from January to December 2000, we found that 1.6% of the total admission was diagnosed to be either MRSA infected or colonised, with an average of three new MRSA cases detected per month. A significant proportion of patients (23%) were diagnosed within the first 48h of admission. Both hip joint surgery, especially emergency procedures for femoral neck fractures, and the presence of a wound presented higher risk of infection. The Intensive Care Unit (ICU) did not appear to be a significant source for intra-hospital dissemination among the orthopaedic patients. MRSA infection or colonisation contributed to an increased length of hospital stay; 88 days compared to 11 days on average for non-MRSA patients; 41% of the positive patients still carried MRSA on discharge. Our data show the importance of diagnosing MRSA in orthopaedic surgery and emphasises that understanding its epidemiology will be crucial to secure a decrease in the incidence of MRSA. Hand hygiene, patient screening, careful surveillance of infections and the prompt implementation of isolation policies, are essential components of control.

Methicillin-resistant Staphylococcal aureus evolution in Australia over 35 years

Australia has a long association methicillin-resistant Staphylococcus aureus (MRSA). Its unique geographic and demographic features have led to the emergence and spread of three types of MRSA over 35 years. Classical multiresistant hospital-acquired MRSA were first noted in Australia in 1965. By the end of the 1970s, strains of this type of MRSA were well established in the complex tertiary care hospitals in the capital cities on the eastern seaboard of mainland Australia. Characterized by resistance to beta-lactams, erythromycin, tetracycline, gentamicin, and trimethoprim-sulfamethoxazole, these strains have persisted and diversified genetically and have acquired a variety of new resistances. They have proven pathogenicity and are a prominent cause of hospital infection in the endemic institutions. More recently they have become endemic in some central state tertiary care hospitals. Community-acquired strains of MRSA first appeared in the north of Western Australia in the mid-1980s. Strains have subsequently appeared in the south of the state and in the two adjacent central states, and are more frequently isolated from Aboriginal patients. Although harboring few or no additional resistances apart from resistance to beta-lactams initially, these strains are also accumulating additional resistances. A different variety of community-acquired MRSA has recently been noted in eastern Australia. It has a similar antibiogram to the western strains, but an entirely different epidemiology, resembling that currently being experienced in parts of New Zealand, and associated with patients of south Pacific island origin.

Improved management of infrainguinal bypass graft infection with methicillin-resistant Staphylococcus aureus

BACKGROUND

There is considerable debate over the management of infected infrainguinal grafts. This report describes recent experience in this field and documents the change in clinical practice needed to deal with methicillin-resistant Staphylococcus aureus (MRSA).

METHODS

All infected infrainguinal grafts between January 1991 and July 1997 were reviewed. In the light of the findings, clinical practice was modified considerably. A further 1 year was audited prospectively up to August 1998.

RESULTS

Twenty-six patients were treated for 27 infrainguinal graft infections (25 prosthetic, two vein). Twenty were treated by complete graft excision as the initial therapy; graft preservation was attempted in six patients. Before 1995, the infecting organisms were predominantly Pseudomonas aeruginosa or methicillin-sensitive staphylococci. Subsequently all 14 patients treated up to 1997 had infection with MRSA. The overall amputation rate was 17 of 26; ten amputations were in patients with MRSA. Four patients died, all with MRSA sepsis. As a result of this experience a policy of complete isolation was adopted for all patients infected with MRSA. In the 12 months since this policy was introduced, 77 infrainguinal grafts (61 vein, 16 prosthetic) have been inserted. Two grafts (3 per cent) have become infected, necessitating graft excision and amputation.

CONCLUSION

MRSA infection of an infrainguinal graft is a serious complication with high associated amputation and mortality rates. Isolation and barrier nursing appeared to contain the problem.

Long-term efficacy of a program to control methicillin-resistant Staphylococcus aureus

The long-term efficacy of a program to control methicillin-resistant Staphylococcus aureus (MRSA) was evaluated in a 350-bed university hospital. Three periods were monitored: pre-epidemic (January 1989-November 1989), outbreak (December 1989-June 1990) and control program (July 1990-December 1992) periods. Control measures included cohort isolation, patient care measures and therapy (oral cotrimoxazole plus fusidic acid ointment) of MRSA carriage in patients, roommates and personnel. A total of 117 MRSA-infected patients were detected. For each period respectively, MRSA incidence (number of cases per 1,000 patient-days) was 3.2, 8.2 and 2.0 in the intensive care unit (ICU) and 0.08, 0.23 and 0.26 in the general wards. During the outbreak there was a 2.7-fold overall increase of baseline MRSA incidence (p < 0.02). The crude mortality was 68% and the attributable mortality was estimated to be 50%. The program was estimated to have prevented 76% (CI95 28-91, p < 0.0001) of expected MRSA cases and 85% (CI95 62-94, p < 0.0001) of expected fatalities due to MRSA in the ICU, but it had no significant effect in the general wards. The program did not control vancomycin consumption.

Methicillin-resistant Staphylococcus aureus infections following esophageal surgery in patients with impaired defense mechanisms

This study was conducted to determine whether or not compromised host defense mechanisms prior to surgery are related to postoperative infections with methicillin-resistant Staphylococcus aureus (MRSA). Neutrophil cytocidal activities, serum complement and immunoglobulin levels, the in vivo antibody-producing capacity against pneumococcal polysaccharide (PPS), and cell-mediated immunity (CMI) were evaluated in 22 patients who underwent esophagectomy for esophageal cancer between 1989 and 1990. Postoperatively, nine patients developed MRSA infections. Anti-PPS IgG was found to be significantly lower in patients with MRSA infections than in those without (P < 0.01). All the patients with MRSA infections showed a titer < 600 EU, while all but one of the non-infected patients showed a titer > 600 EU. Impairment in other components of the defense mechanisms, apart from a partial deficiency of CMI, did not differ between the groups. Thus, a preoperative evaluation of the antibody-producing capacity may serve to predict the development of MRSA-related infections following major surgery such as esophagectomy.

A seven-year experience with methicillin-resistant Staphylococcus aureus

From July 1983 through June 1990, 319 patients with methicillin-resistant Staphylococcus aureus (MRSA) were identified at the University of California, Davis Medical Center. Initially, our goal was eradication of MRSA from the hospital flora. Our approach was: (a) immediate notification of all MRSA isolates by the microbiology laboratory; (b) strict isolation; (c) cohorting; (d) bathing patients with an iodophor; (e) surveillance cultures of patients and staff; (f) treatment of all colonized persons; and (g) strict isolation on readmission. Control of spread was achieved but eradication was not. In 1987 our strategy was modified in order to establish the least restrictive methods to maintain control of the spread of MRSA. After notification by the microbiology laboratory, we now require: (a) contact isolation; (b) surveillance cultures of patients associated with each new case; and (c) contact isolation for all MRSA patients on readmission. Strict isolation and employee culturing are used only during major outbreaks. We have averaged four new cases of MRSA per month over the 7-year period, including four major outbreaks. Since 1987, we have averaged only three new cases per month with one major MRSA outbreak. Annual cost savings of greater than $50,000 have been realized through the policy modifications. We conclude that the use of contact isolation with some modifications has saved time and money and has successfully controlled the spread of MRSA in our university hospital.

Successful control of endemic MRSA in a cardiothoracic surgical unit

After a substantial increase in the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in the Cardiothoracic Surgical Unit at St. Vincent's Hospital, Sydney, a prospective study was undertaken in early 1986 to ascertain the carrier status of all patients entering the Unit. Of 84 patients, 27.4% were found to carry MRSA and the perineum was the major site of carriage, with 69.6% of MRSA positive cases carrying the organism in this site. As a result of these findings, the period of perioperative antibiotic cover was shortened, whole-body washing of patients with a 1% triclosan preparation was instituted and routine postoperative perineal swabs were taken. During the 18 months after implementation of these policies, a highly significant reduction in the number of MRSA carriers and infections was observed. The monitoring of perineal colonization proved to be a useful marker for increases in MRSA in the Unit.

Genetic heterogeneity in methicillin-resistant strains of Staphylococcus aureus revealed by esterase electrophoretic polymorphism

136 methicillin-resistant strains of Staphylococcus aureus recovered from hospitalized patients in 18 countries were characterized by electrophoretic mobilities of three types of esterases. These were defined by their ranges of activity toward five synthetic substrates and their resistance to di-isopropyl fluorophosphate. Fourteen zymotypes were distinguished. Two, designated as 6 and 14, were found in 53 and 50 strains, respectively. Genetic diversity coefficients were lower for strains from France and from other European countries (H = 0.47 and 0.53, respectively) than for strains from North America (H = 0.79). On the basis of electrophoretic polymorphism of esterases, our work provides evidence that methicillin-resistance is expressed in genetically different strains. Variations in esterase electrophoretic pattern within methicillin-resistant strains of S. aureus can make a significant contribution to the study of their epidemiology.

Methicillin-resistant Staphylococcus aureus in two burn units: clinical significance and epidemiological control

Routine isolation adequately controlled MRSA strains in two burns units with a restrictive antibiotic policy. Ventilation control and more rigorous change of clothing offered no further advantage. No carriers among staff were found, but some suffered minor skin lesions that were the source of further MRSA spread. Spread of MRSA from the unit to other parts of the hospital was prevented by early identification of colonized patients and by restricting patient and staff movement.

A descriptive survey of uncontrolled methicillin-resistant Staphylococcus aureus in a twin site general hospital

Over a five year period beginning in 1981, during which control measures were applied intermittently, the incidence of methicillin-resistant Staphylococcus aureus (MRSA) isolates increased steadily within a twin site general hospital. A retrospective chart review of 154 patients identified in 1984-1985 showed that the MRSA 'definitely' contributed to three deaths (2%) and 'probably' contributed to a further 15 (10%). The prolonged median duration of hospital admission (22 days) before first isolation of MRSA, together with the clustering of cases in time on certain wards, suggested that most, if not all, affected patients acquired the MRSA in hospital. As the virulence of MRSA in our outbreak appeared the same as that reported from teaching hospitals, MRSA control measures need to be comprehensively applied in general hospitals.

Methicillin resistant Staphylococcus aureus; the role of antisepsis in the control of an outbreak

Between February 1983 and September 1985, an outbreak of methicillin-resistant Staphylococcus aureus involving 151 patients and staff occurred in a district general hospital. At its peak, 43 cases occurred in 3 months. Sixty-two patients suffered morbidity and two died. Conventional isolation techniques and once-daily whole body washing of affected patients with triclosan successfully controlled the outbreak.

Plasmid analysis of simultaneous nosocomial outbreaks of methicillin-resistant Staphylococcus aureus

A large outbreak of infections caused by methicillin and aminoglycoside resistant Staphylococcus aureus provided the opportunity to evaluate mechanisms of resistance and compare the usefulness of typing systems. Between January 1979 and December 1980, 63 patients developed infections with S aureus resistant to multiple antibiotics, including methicillin and tobramycin. All isolates had an identical antibiogram and were phage type 47/54/75/77/83A. Beginning in January 1981, a superimposed outbreak caused by S aureus of the same phage type but with a resistance pattern now including gentamicin occurred. The two strains contained different aminoglycoside inactivating enzymes. The initial strain contained a single plasmid of 21.5 mDa molecular weight, whereas the subsequent strain which had acquired gentamicin resistance contained this plasmid plus a heavier one of 33 mDa. Plasmid analysis complements the analysis of antibiograms and phage types and aids in defining epidemiologic patterns of transmission.

The management of methicillin-resistant Staphylococcus aureus in a major hospital

A reduction in the incidence and duration of methicillin-resistant Staphylococcus aureus infection and colonization was obtained by the introduction of a rigorous control programme. This included computerization of data, improved nursing practices and an antiseptic routine.

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

Three general strategies for the control of Staphylococcus aureus, particularly methicillin-resistant Staph. aureus (MRSA), are described based on experience in Melbourne, Australia from 1975 to 1984, when such strains have been common. The strategies have been named (1) the Scutari Strategy, based on simple hygienic measures and barrier nursing, (2) the search and destroy technique, with strict isolation of all infected and colonized patients, and attempts to eradicate MRSA from the environment, and (3) the SALT strategy (Staph. aureus limitation techniques) with isolation only for non-containable infections, and 'infectious precautions' for other MRSA infections and for colonized patients.