An outbreak of methicillin resistant Staphylococcus aureus infection in a rugby football team.

Outbreaks of infection caused by methicillin resistant Staphylococcus aureus are common in hospitals and nursing homes, but until now none have been reported in the community. This is a report of an outbreak involving five members of a rugby football team.

Resistance to methicillin and other antibiotics in isolates of Staphylococcus aureus from blood and cerebrospinal fluid, England and Wales, 1989-95.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) strains are colonising hospital patients in most areas of England and Wales, UK. The extent to which they cause invasive infection can be gauged from their presence in isolates from blood or cerebrospinal fluid. METHODS: About 200 clinical laboratories reported the results of susceptibility testing of between 4501 and 6370 isolates of S aureus from blood or cerebrospinal fluid in each of the years 1989-95. We assessed the rate of resistance to methicillin and other antibiotics for each of these years. FINDINGS: Resistance to methicillin was stable at about 1.5% of isolates during 1989-91, but increased thereafter to 13.2% in 1995 (p < 0.001). At the same time there was a significant increase in the percentage of isolates resistant to erythromycin, clindamycin, ciprofloxacin, gentamicin, trimethoprim, and rifampicin (p < 0.001 for each)-resistance characteristics often seen in MRSA. Resistance to benzylpenicillin increased slightly but significantly (p < 0.001); resistance to fusidic acid was stable (p > 0.05); resistance to tetracycline decreased significantly (p < 0.001). INTERPRETATION: Among cases of S aureus bacteraemia, the proportion due to MRSA has increased significantly. Bacteraemia due to MRSA has a poor prognosis, especially if not treated with suitable antibiotics. Therefore, these findings are important, especially for management of patients and the development of antibiotic policies.

International quality control of phage typing of Staphylococcus aureus. International Union of Microbial Societies Subcommittee.

A questionnaire was sent to the 48 national typing centres for Staphylococcus aureus and 31 replies were received. Methods of phage typing varied and molecular methods were not universally available, although pulsed-field gel electrophoresis was offered by 13 centres. Results for a quality control phage typing exercise were received from 25 centres. Increased standardisation of methods and definitions are indicated. Differences from the consensus patterns were mainly due to typing at an inappropriate dilution of phage, but five strains caused difficulties in many centres. Overall reproducibility was good. Phage typing remains a cost-effective method for epidemiological studies, particularly on a large scale. The strains selected for the quality control exercise included many strains suitable for controlling molecular methods as well as testing phage typing. Molecular methods help in the validation of the conclusions which may be drawn from phage typing.

A major outbreak of methicillin-resistant Staphylococcus aureus caused by a new phage-type (EMRSA-16)

An outbreak of methicillin-resistant Staphylococcus aureus (MRSA) infection caused by a novel phage-type (now designated EMRSA-16) occurred in three hospitals in East Northamptonshire over a 21-month period (April 1991--December 1992). Four hundred patients were colonized or infected. Seven patients died as a direct result of infection. Chest infections were significantly associated with the outbreak strain when compared with methicillin-sensitive S. aureus. Twenty-seven staff and two relatives who cared for patients were also colonized. A 'search and destroy' strategy, as advocated in the current UK guidelines for control of epidemic MRSA was implemented after detection of the first case. Despite extensive screening of staff and patients and isolation of colonized and infected patients, the outbreak strain spread to all wards of the three hospitals except paediatrics and maternity. A high incidence of throat colonization (51%) was observed. Failure to recognize the importance of this until late in the outbreak contributed to the delay in containing its spread. Key parts of the strategy which eventually contained the local outbreak were the establishment of isolation wards in two hospitals, treatment of all colonized patients and staff to eradicate carriage and screening of all patients upon discharge from wards where MRSA had ever been detected. EMRSA-16 spread to neighbouring hospitals by early 1992 and to London and the South of England by 1993. It is distinguished from other epidemic strains by its characteristic phage-type, antibiogram (susceptibility to tetracycline and resistance to ciprofloxacin), and in the pattern given on pulse field electrophoresis.

A double outbreak of exfoliative toxin-producing strains of Staphylococcus aureus in a maternity unit.

This report describes a double outbreak of staphylococcal scalded skin syndrome (SSSS) in which two distinct tetracycline-resistant strains of Staphylococcus aureus producing different exfoliative toxins were involved. In the first phase the daytime staff of the delivery unit and eczematous skin conditions in midwives were implicated as the probable source. In the second phase a source within a post-natal ward was suggested with local cross-infection. In the final phase both sources were epidemiologically linked to cases of SSSS. Because early discharge was the policy of the unit many cases presented in the community rather than in the hospital. Confirmation of epidemiological findings was provided by additional laboratory studies. Two distinct strains of S. aureus could be defined, differing in phage-typing patterns, the exfoliative toxin produced, plasmid profile, cadmium resistance and bacteriocin production. Strict care in hand washing with a chlorhexidine-containing detergent was an important control measure.

Some properties of coagulase-negative staphylococci isolated from cases of ovine mastitis.

Of 41 coagulase-negative staphylococcal isolates from cases of ovine mastitis, 80% were speciated by the 'API-Staph SYSTEM' and 90% by a combination of biochemical tests. Staphylococcus simulans and Staph. xylosus were the two most prevalent species.

Ribotyping of Staphylococcus aureus: an assessment using well-defined strains.

Ribotyping, with homologous or heterologous (Escherichia coli) r-RNA, of the propagating strains for phages of the international set for strains of Staphylococcus aureus of human origin was undertaken to determine the discrimination of this typing method. Ribotyping could distinguish between strains of different phage groups, but could not distinguish between seven phage group III strains of different phage type. Ribotying may be a useful adjunct to phage typing in S. aureus but is unlikely to replace it as the primary method of epidemiological typing.

Lectin typing of methicillin-resistant Staphylococcus aureus from Singapore, England and Wales, and Denmark.

Methicillin-resistant Staphylococcus aureus (MRSA) isolates from a possible outbreak in Singapore (84) were examined together with all MRSA isolated in Denmark in 1986-1990 (58) and 14 distinct epidemic and 10 distinct single hospital strains from England and Wales. All 84 Singapore isolates were phage typed routinely and 52 isolates were further analysed together with the Danish isolates with an additional set of experimental phages and by lectin typing. The British strains, previously phage typed in the same way, were lectin typed. The following lectins were used: wheat-term agglutinin, soy-bean agglutinin, tomato lectin and Concanavalin-A. Routine phage typing of the Danish isolates showed that 41 isolates belonged to 19 different types; 17 isolates were non-typable (NT). Addition of experimental phage typing and lectin typing enhanced discrimination to 47 types. The 24 British strains could be divided into eight [corrected] "lectin types". Sixty-one of the isolates from Singapore were non-typable by phage typing; the remaining 23 strains belonged to five types. Further examination of 52 isolates with the experimental set of phages and by lectin typing gave 14 closely related types; 48% of these isolates belonged to only two types.

Nosocomial spread of Staphylococcus aureus showing intermediate resistance to methicillin.

A nosocomial outbreak of infection and colonization involving six patients and caused by a strain of Staphylococcus aureus showing intermediate resistance to methicillin (MIC = 4-8 mg l-1) is described. The outbreak was associated with skin-carriage of the epidemic strain by a nurse suffering from severe eczema. The reduced susceptibility of the outbreak strain to methicillin was associated with beta-lactamase production. Elimination or inhibition of beta-lactamase activity produced a two-fold decrease in methicillin MIC. There was no evidence for the presence of either penicillin-binding protein 2a or the corresponding mec gene, which mediate resistance in fully methicillin-resistant strains.

Enterotoxins and toxic-shock syndrome toxin-1 in non-enteric staphylococcal disease.

Over the 7 years 1985-91, 997 strains of Staphylococcus aureus from 962 patients with diseases other than food poisoning have been tested for the production of enterotoxins and toxic shock syndrome toxin-1 (TSST-1) and phage typed. In all, 128 cases could be classified as confirmed or probable toxic shock syndrome (TSS) but a further 199 cases were classified as possible or unconfirmed TSS. In 219 cases, an alternative diagnosis could be supported and 45 cases were classified as sudden infant death syndrome. In 371 cases, insufficient information for classification was available. Strains of phage group I producing TSST-1 were associated with menstrual TSS. Many menstrual TSS cases were aged less than 20 and were using non-introducer tampons. When all strains were reviewed, strong associations were observed between TSST-1 production and phage group I strains, enterotoxin B production and group V strains, enterotoxin C and phage-type 95 strains and between enterotoxin A without TSST-1 and phage group III strains.

Evaluation of methods for typing coagulase-negative staphylococci.

One hundred and forty-two coagulase-negative staphylococci (CNS) isolated from dialysate effluent or skin of patients receiving continuous ambulatory peritoneal dialysis (CAPD) were typed by extended antibiogram (16 antibiotics) and biotype (26 reactions). These isolates were then typed by supplementary methods to determine the most suitable typing method for an epidemiological study of antibiotic resistance. These included phage typing, reverse phage typing, plasmid typing, whole-cell protein typing by SDS-PAGE with analysis by densitometry, and immunoblotting. The percentage of isolates typed successfully by the supplementary methods were: phage typing 20%, reverse phage typing 0%, plasmid typing 66%, SDS-PAGE 100%, immunoblotting 100%. The discrimination of each method was: phage typing 20%, plasmid typing 37%, SDS-PAGE 69%, immunoblotting 57%. Reproducibility was 88% for phage typing and 97% for plasmid typing. The reproducibility of the whole-cell protein typing was 83% if the same extracts were used but only 43% when separate protein extracts were analysed on separate occasions. However, strain relatedness was highly reproducible. The determination of an antibiogram-biotype profile was not a sufficiently accurate typing method for an epidemiological study of antibiotic resistance. Whole-cell protein typing by SDS-PAGE or immunoblotting was technically demanding but was the most effective of the supplementary methods for detecting erroneous discrimination and false matching produced by antibiogram-biotype combinations.

An epidemic methicillin-resistant strain of Staphylococcus aureus in Spain.

During 1990, a strain of methicillin-resistant Staphylococcus aureus became epidemic in Spain and spread in a manner analogous to that of EMRSA-1 in England. Isolates of this strain produced little protein A and were resistant to a number of antibiotics including ciprofloxacin. Beta-lactamase production was encoded by a c. 39 kb plasmid, which also conferred resistance to mercury, cadmium, ethidium bromide and propamidine isethionate. Investigation showed that two variants, separable by supplementary and Fisk phage typing, were circulating. The B variant appeared to spread more readily than the A variant. The opportunity was taken to compare the discriminatory power of traditional typing methods with molecular techniques. The discriminatory power of the molecular techniques used only reached the same level as the traditional methods when double enzyme digestion of total cellular DNA by EcoR I and Cla I was performed.

Methicillin-resistant Staphylococcus aureus in England and Wales.

Methicillin-resistant Staphylococcus aureus (MRSA) were detected soon after the introduction of methicillin in 1960, and reports of their isolation increased up to 1971. Changes in antibiotic usage were associated with a fall and then, in the early 1980s, a further rise in the number of reports. This article reviews the various surveys that have been conducted to establish the frequency, distribution and strain varieties of MRSA. The first strain to be recognised as epidemic (ie, affecting more than one hospital), was defined by phage typing and antibiogram, confirmed with molecular typing, and designated EMRSA-1. It was first detected in 1981 and became progressively more widespread until it began to decline in 1987. Only three health regions reported this strain in the first quarter of 1991. EMRSA-2 has remained restricted to the South East and South West Thames regions. EMRSA-3 appeared in the South East Thames region in 1987 and has since spread, being reported from eight health regions in the first quarter of 1991. At least 11 other strains of MRSA affecting more than one hospital have been detected and ten endemic strains (restricted to single hospitals) have been identified. Imported strains of MRSA, often introduced following the repatriation of road traffic accident victims, may include strains with epidemic potential and local spread has followed importation in at least two incidents. Continued surveillance of epidemic MRSA strains and the search for simple and widely applicable markers, such as unusual antibiotic resistance patterns or biochemical features, are needed for the prompt application of control measures.

Surveillance of methicillin-resistant Staphylococcus aureus in England and Wales, 1986-1990.

The incidence of methicillin-resistant Staphylococcus aureus in England and Wales was monitored by a weekly reporting scheme from early 1986 to March 1990. Potential coverage was approximately two-thirds of hospital beds. Reporting centres fell from a peak of 210 in 1986 to a low of 101 centres early in 1989 with later recovery. There were 2367 positive reports in 1986, 2174 in 1987, 1700 in 1988, 1701 in 1989 and 632 in the first quarter of 1990. Colonizations outnumbered infections by 2:1. There were marked regional differences: North-East Thames was dominant in 1986 and 1987, and then declined; South-East Thames showed a dramatic increase in 1988 which continued. Other regions showed less significant changes but there were continuing problems in the South-Western Region and in the West Midlands. Some of these changes were related to the decline of EMRSA-1, possibly due to the introduction of effective control measures, and to the emergence of EMRSA-3 in South-East Thames and its spread to Wessex.