An epidemiological study of methicillin-resistant Staphylococcus aureus (MRSA) isolated from medical staff, inpatients, and hospital environment in one ward at our 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.

MRSA and the environment: implications for comprehensive control measures

Environmental contamination with methicillin-resistant Staphylococcus aureus (MRSA) is established soon after colonized or infected patients become resident. There are many studies that detail the mechanisms of spread and environmental survival of methicillin-susceptible Staphylococcus aureus (MSSA); this knowledge translates directly into the same findings for MRSA. The potential ubiquity of MRSA in a health-care setting poses challenges for decontamination. Whereas patients and medical staff are important sources for MRSA spread, the environmental burden may contribute significantly in various contexts. Effective control measures must therefore include consideration for MRSA in the environment.

The efficiency of an air filtration system in the hospital ward

A study was conducted to ascertain the efficiency and effectiveness of an air filtration system (Electromedia Model 100C, Clean Air UK, UK) in the hospital ward. The sampling was conducted using a portable Surface Air Sampler (Cherwell Laboratories, Bicester, UK) in conjunction with settle plates. Samples were taken two days before and two days following activation of the filtration system and results compared. A clear, demonstrable, statistically significant reduction in microbial organisms following the activation of the filtration systems is evident (81% settle plates; 24% Surface Air Sampler). This study has implications for the improved health and welfare of patients and healthcare workers who may benefit through the implementation of such a system.

Survey of dental hygienists and healthcare workers for microorganisms in the oral cavity

Over 350 bacterial species are known to form communities on tooth surfaces in the oral cavity, and opportunistic pathogens are frequently isolated from samples taken from the oral cavities of immunocompromised hosts, as well as elderly people with poor oral hygiene. To confirm the correlation between the prevalence of opportunistic pathogens in the oral cavity and oral hygiene, dental plaque and saliva samples from 15 dental hygienists and 15 healthcare workers were investigated. No opportunistic pathogens were found in the samples from dental hygienists, however, they were isolated from 10 of the 15 healthcare workers (66.7%). The total amounts of Streptococcus sp. and Lactobacillus sp. were also significantly higher in the healthcare workers. The amount of Streptococcus mutans was also higher, although the difference was not significant. From our results, we concluded that the prevalence of opportunistic pathogens and cariogenic bacteria in the oral cavity may be reduced by proper oral hygiene measures.

Combined use of ribotyping, PFGE typing and IS431 typing in the discrimination of nosocomial strains of methicillin-resistant Staphylococcus aureus

We have previously reported the phenotypic characterization of methicillin-resistant Staphylococcus aureus (MRSA) clinical strains isolated in Malaya University Hospital in the period 1987 to 1989 using antibiogram, coagulase typing, plasmid profiles, and phage typing. Here, we report the analysis of the same strains with three genotyping methods; ribotyping, pulsed-field gel electrophoresis (PFGE) typing, and IS431 typing (a restriction enzyme fragment length polymorphism analysis using an IS431 probe). Ribotyping could discriminate 46 clinical MRSA strains into 5 ribotypes, PFGE typing into 22 types, and IS431 typing into 15 types. Since the differences of the three genotyping patterns from strain to strain were quite independent from one another, the combined use of the three genotyping methods could discriminate 46 strains into 39 genotypes. Thus, the powerful discriminatory ability of the combination was demonstrated.

Staphylococcus aureus isolated from nostril anteriors and subungual spaces of the hand: comparative study of medical staff, patients, and normal controls

An epidemiologic investigation of methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus aureus (S. aureus) colonization was conducted at Kansai Medical University Hospital between 1990 and 1991. The incidence of nasal and subungual positivity for S. aureus was examined in a total of 156 subjects including inpatients, physicians, and nurses at a ward for dermatology, plastic surgery, and emergency patients, outpatients with atopic dermatitis and other skin diseases, and normal controls. Inpatients were most heavily colonized with MRSA (40.8%), but S. aureus colonization was most frequent in outpatients with atopic dermatitis (95.5%). Not only nostrils, which have been much discussed as a reservoir of S. aureus, but also subungual spaces seemed to be havens of S. aureus. Twelve out of 22 atopic dermatitis patients were positive for S. aureus on skin regions, and coagulase and phage testing showed a correlation between the nasal and skin-colonizing S. aureus. Coagulase type II and phase type NT (not typable) were the predominant types of S. aureus, including MRSA.

Study of the efficacy of antiseptic handrub lotions with hand washing machines

The effectiveness of quick handwashing in regards to four alcohol-based handrub lotions, including two products already on the market and our original lotions 1, 2, with two different kinds of hand washing machines was studied in vivo. We also tried to evaluate the efficacy of the four lotions in vitro. The in vivo testing of each lotion, including ethanol, was evaluated using two hand washing methods, first with and then without a previous soap wash. Computerized image analysis was used to calculate the bacterial count on the hand surface. The results showed that a 3 second application of the original lotion 2 (0.5% chlorhexidine in a 77% ethyl alcohol solution) preceded by a soap wash eradicated 89.3% of the bacteria on the hands; this was the highest reduction rate of all four detergents. AROKULIN-E (67.9% ethyl alcohol solution) without a prior handwashing produced the lowest reduction, 49.1% against hand surface bacteria. These results were compatible with those in vitro. It seems that an alcohol-based solution containing an effective antimicrobial detergent preceded by a soap wash is necessary to acceptably reduce hand surface bacteria.

The incidence of isolation of methicillin-resistant Staphylococcus aureus (MRSA) strains from skin infections during the past three years (1989-1991)

We did a statistical study of 294 strains of Staphylococcus aureus (S. aureus) isolated from skin infections during the period from January of 1989 to December of 1991 in the Department of Dermatology, Kansai Medical University Hospital. We especially examined methicillin-resistant S. aureus (MRSA) from the point of view of incidence, variety of skin infections with MRSA, coagulase type, phase type, and resistance against antimicrobial agents. The frequency of isolation of MRSA has been increasing. In 1991, the proportion of MRSA isolates among all S. aureus strains isolated from skin infections was 41.5%. MRSA was isolated most often from infectious decubitus. Coagulase type II and phage group NT (not typable) MRSA were most frequently isolated. The resistance of MRSA to OFLX and IMP/CS had remarkably increased. Notably, the resistance to MINO was low before 1991.