Management of Outbreaks of Methicillin-ResistantStaphylococcus aureusInfection in the Neonatal Intensive Care Unit: A Consensus Statement

Objective.

In 2002, the Chicago Department of Public Health (CDPH; Chicago, Illinois) convened the Chicago-Area Neonatal MRSA Working Group (CANMWG) to discuss and compare approaches aimed at control of methicillin-resistantStaphylococcus aureus(MRSA) in neonatal intensive care units (NICUs). To better understand these issues on a regional level, the CDPH and the Evanston Department of Health and Human Services (EDHHS; Evanston, Illinois) began an investigation.

Design.

Survey to collect demographic, clinical, microbiologic, and epidemiologic data on individual cases and clusters of MRSA infection; an additional survey collected data on infection control practices.

Setting.

Level III NICUs at Chicago-area hospitals.

Participants.

Neonates and healthcare workers associated with the level III NICUs.

Methods.

From June 2001 through September 2002, the participating hospitals reported all clusters of MRSA infection in their respective level III NICUs to the CDPH and the EDHHS.

Results.

Thirteen clusters of MRSA infection were detected in level III NICUs, and 149 MRSA-positive infants were reported. Infection control surveys showed that hospitals took different approaches for controlling MRSA colonization and infection in NICUs.

Conclusion.

The CANMWG developed recommendations for the prevention and control of MRSA colonization and infection in the NICU and agreed that recommendations should expand to include future data generated by further studies. Continuing partnerships between hospital infection control personnel and public health professionals will be crucial in honing appropriate guidelines for effective approaches to the management and control of MRSA colonization and infection in NICUs.

An investigation of MRSA infection in a hospice

This study investigated the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) carriage and infection among patients admitted to a hospice. Under the existing policy at this hospice, only patients admitted from hospital wards where MRSA is known to be present are screened for MRSA prior to transfer. Hence the investigators were keen to study patients transferred from settings other than this. One hundred and twenty patients, all either from the community or from hospital wards without known MRSA, were entered into the study ('study group') and were swabbed for MRSA on admission to the hospice. Swabbing was continued at weekly intervals until discharge or death. Of the 120 patients, seven (5.8%) were MRSA positive on admission. A further four patients who were negative on admission showed MRSA on later swabs. Another two patients developed symptomatic infections during admission that were proven to be due to MRSA, but neither of these had shown MRSA on any swabs taken during the study. During the study period, a separate group of 156 patients was swabbed routinely before transfer from hospital wards where MRSA was known to be present in accordance with hospice policy ('non-study group'). Of these patients, 11 (7.1%) were found to be colonized with MRSA but none developed associated symptomatic infection. It appears that the risk of symptomatic infection with MRSA in hospice patients is low, and the burden placed on this vulnerable group by conventional eradication regimes may be disproportionate to any benefit derived.

Brazilian phytopharmaceuticals - evaluation against hospital bacteria

Pharmaceutical companies have demonstrated renewed interest in investigating higher plants as sources for new lead structures and also for the development of standardized phytotherapeutic agents of proven efficacy, safety and quality. This work analysed three commercial phytopharmaceuticals against multi-resistant bacteria of medical importance, including methicillin-resistant Staphylococcus aureus isolates from the Brazilian endemic clone. From the phytopharmaceuticals assayed, plants from the products 'Astmoflora' and 'Kókolos' were considered active, while plants from 'Uva do Mato' were not active in the tested concentrations, which ranged from 62.5 to 500 microg/mL. Among fractions of Aristolochia cymbifera and Myroxylon balsamum, the hexane extracts showed the best results against Staphylococcus spp. and Pseudomonas aeruginosa. These fractions showed growth inhibition of all methicillin-sensitive and -resistant Staphylococcus aureus strains and the majority of the Pseudomonas aeruginosa strains at a concentration of 500 microg/mL. Bioassay-guided fractionation of hexane extracts of Aristolochia cymbifera and Myroxylon balsamum led to the identification of the diterpene 2-oxo-populifolic acid and of the chalcone isoliquiritigenin, respectively, as antimicrobial compounds.

Nosocomial transmission of methicillin-resistant Staphylococcus aureus: a blinded study to establish baseline acquisition rates

OBJECTIVE

To define the extent of nosocomial transmission of methicillin-resistant Staphylococcus aureus (MRSA) in patients admitted to a tertiary-care hospital.

DESIGN

A blinded, prospective surveillance culture study of patients admitted to the hospital to determine the transmission (acquisition) rate of MRSA. Risk factors associated with the likelihood of MRSA colonization on admission were investigated.

SETTING

Tertiary-care military medical facility.

PARTICIPANTS

All patients admitted to the medicine, surgery, and pediatric wards, and to the medical, surgical, and pediatric intensive care units were eligible for inclusion.

RESULTS

Five hundred thirty-five admission and 374 discharge samples were collected during the study period. One hundred forty-one patients were colonized with methicillin-susceptible S. aureus (MSSA) and 20 patients (3.7%) were colonized with MRSA on admission. Of the 354 susceptible patients, 6 acquired MRSA during the study for a transmission rate of 1.7%. Patients colonized with MRSA on admission were more likely to be older than non-colonized or MSSA-colonized patients, to have received antibiotics within the past year, to have been hospitalized within the prior 3 years, or to have a known history of MRSA. Patients acquiring MRSA had an average hospital stay of 17.7 days compared with 5.3 days for those who did not acquire MRSA. Pulsed-field gel electrophoresis of the 6 MRSA isolates from patients who acquired MRSA revealed 4 distinct band patterns.

CONCLUSIONS

Most patients colonized with MRSA were identified on admission samples. Surveillance cultures of patients admitted may help to prevent MRSA transmission and infection.

An epidemiologic survey of methicillin-resistant Staphylococcus aureus by combined use of mec-HVR genotyping and toxin genotyping in a university hospital in Japan

OBJECTIVE

To evaluate the usefulness of an assay using two polymerase chain reaction-based genotyping methods in the practical surveillance of methicillin-resistant Staphylococcus aureus (MRSA).

METHODS

Nosocomial infection and colonization were surveyed monthly in a university hospital in Japan for 20 months. Genotyping with mec-HVR is based on the size of the mec-associated hypervariable region amplified by polymerase chain reaction. Toxin genotyping uses a multiplex polymerase chain reaction method to amplify eight staphylococcal toxin genes.

RESULTS

Eight hundred nine MRSA isolates were classified into 49 genotypes. We observed differing prevalences of genotypes for different hospital wards, and could rapidly demonstrate the similarity of genotype for outbreak isolates. The incidence of genotype D: SEC/TSST1 was significantly higher in isolates causing nosocomial infections (49.5%; 48 of 97) than in nasal isolates (31.4%; 54 of 172) (P = .004), suggesting that this genotype may represent the nosocomial strains.

CONCLUSION

The combined use of these two genotyping methods resulted in improved discriminatory ability and should be further investigated.

The best hospital practices for controlling methicillin-resistant Staphylococcus aureus: on the cutting edge

OBJECTIVE

A performance improvement task force of Rhode Island infection control professionals was created to develop an epidemiologic model of statewide consistent infection control practices that could reduce the spread of methicillin-resistant Staphylococcus aureus (MRSA).

DESIGN

This model encompasses screening protocols, isolation techniques, methods of cohorting positive patients, decolonization issues, postexposure follow-up, microbiology procedures, and standardized surveillance methodologies. These "best practice guidelines" include three categories of recommendations that define priority levels based on the availability of scientific data.

SETTING

From 1995 through 2000, several Rhode Island hospitals experienced a fivefold increase in nosocomial acquisition of MRSA PARTICIPANTS: Rhode Island infection control professionals are a highly interactive group in the unique position of sharing patients and ultimately experiencing similar trends and problems.

INTERVENTION

The task force collaborated on developing the best hospital infection control practices to prevent and control the spread of MRSA in Rhode Island.

RESULTS

The task force met with local infectious disease physicians and representatives from the Rhode Island Department of Health, the Hospital Association of Rhode Island, and Rhode Island Quality Improvement Partners. Discussions identified numerous and diverse MRSA control practices, issues of consensus, and approaches to resolving controversial methods of reducing the spread of MRSA. The guidelines regarding the best hospital practices for controlling MRSA were finalized 8 months later.

CONCLUSION

These guidelines were distributed to all chief executive officers of Rhode Island hospitals by the Rhode Island Department of Health in December 2001. They were issued separate and apart from any regulations, with the intent that hospitals will adopt them as best hospital practices in an attempt to control MRSA.

Can antibiotic-resistant nosocomial infections be controlled?

Three decades ago infection-control programmes were created to control antibiotic-resistant nosocomial infections, but numbers of these infections have continued to increase, leading many to question whether control is feasible. Meticillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci were major problems during the 1990s. Many hospitals have tried antibiotic control but with limited efficacy against these pathogens. Studies of antibiotic restriction, substitution, and cycling have been promising, but more definitive data are needed. Increased compliance with hand hygiene would help but is unlikely to control this problem alone as a result of frequent contamination of other surfaces even when hands are cleansed and high transmission rates when hand hygiene is neglected. For 17 years, the Centers for Disease Control and Prevention have recommended contact precautions for preventing nosocomial spread of important antibiotic-resistant pathogens. Many studies confirm that this approach works when sufficient active-surveillance cultures are undertaken to detect the reservoir for spread. However, most healthcare facilities have not yet tried this approach.

Infection control measures to limit antimicrobial resistance

Increasing antimicrobial resistance has resulted in a rapidly decreasing array of therapeutic options for infections in the critical care setting. Reports of reduced susceptibility to vancomycin in Staphylococcus aureus raise the possibility of patients being infected with a virulent pathogen for which most antibiotics are ineffective. Infection control methods to contain resistance, exclusive of antimicrobial restrictions, focus on surveillance to identify carriers of resistant organisms, prevention of nosocomial infections, adequate hand hygiene, isolation of patients who harbor resistant organisms, and the use of barrier techniques such as gowns and gloves. Surveillance using clinical isolates alone is inadequate for the identification of the majority of patients who carry resistant organisms. However, it is unclear what intensity of surveillance is needed to control the spread of these organisms in the intensive care unit in nonoutbreak situations. Attempts at eradicating carriage are often unsuccessful when there is extranasal colonization with methicillin-resistant S. aureus. Transmission of resistant organisms is primarily the result of transient contamination of healthcare workers' hands. Adequate handwashing, isolation of carriers, and barrier techniques are all necessary for containing resistance within the intensive care unit, however, compliance with these measures can be compromised by high staff turnover and heavy workload.

Spread of a methicillin-resistant and multiresistant epidemic clone of Staphylococcus aureus in Argentina

One hundred forty-eight recent methicillin-resistant Staphylococcus aureus (MRSA) isolates collected from 13 hospitals in Argentina were examined for antibiotic susceptibility and clonal type, using hybridization with DNA probes specific for mecA and Tn554, and pulsed-field gel electrophoresis (PFGE) of chromosomal SmaI digests. The majority of the isolates (62.2%) shared the common PFGE B pattern and carried variants of mecA and Tn554 polymorphs characteristic of an MRSA clone widely spread in Brazilian hospitals. Similarly to the Brazilian isolates, the MRSA clone recovered in the Argentinian hospitals (XI::B::B) and its close relatives (XI::B'::B, XI::AA::B, XI::M::B, XI::omega omega::B, and III::W::B) showed susceptibility to spectinomycin and resistance to numerous antibacterial agents, including beta-lactams, tetracycline, aminoglycosides, macrolides, trimethoprim/sulfamethoxazole, ciprofloxacin, and fosfomycin, and more than 60% of the isolates were also resistant to chloramphenicol and rifampin. The XI::B::B MRSA clone represented the majority of isolates recovered in most of the hospitals, nine of which were located in the city of Buenos Aires, three in the province of Buenos Aires, and one in the province of Tucumán, 1,312 km northwest of the city of Buenos Aires. The observations document further geographic expansion of this South American MRSA clone across national boundaries.

Control of methicillin-resistant Staphylococcus aureus in the hospital setting

Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of nosocomial infections. Healthcare professionals in the United States should develop programs to prevent transmission of this organism within their institutions. Aggressive control efforts are justified for several reasons: (1) the incidence of nosocomial MRSA reflects the general effectiveness of infection control practice; (2) MRSA do not replace susceptible strains but instead increase the overall rate of nosocomial S. aureus infections; (3) MRSA infections cause substantial morbidity and mortality; (4) serious MRSA infections must be treated with vancomycin. Thus, in hospitals with high rates of MRSA, use of this antimicrobial agent increases, which in turn may increase the risk for selecting vancomycin-resistant enterococci. Hospitals have used numerous different approaches to control nosocomial spread of MRSA. Staff should choose a control method based on the prevalence of MRSA in their institution and in their referring facilities, the rate of nosocomial transmission of MRSA in their hospital, the risk factors present in their patient population, the reservoirs and modes of transmission specific to their hospital, and their resources. Any MRSA control plan must stress adherence to basic infection control measures, such as hand washing and contact isolation precautions. In addition, decolonization of patients and staff, control of antimicrobial use, surveillance cultures, and molecular typing may be helpful adjuncts.