Problems in the investigation of an apparent outbreak of coagulase-negative staphylococcal septicaemia following cardiac surgery.

Two hundred and twenty-six hospital staff and patients were investigated for the carriage of gentamicin-resistant coagulase-negative staphylococci (CNS) during an apparent outbreak of infection after cardiac surgery. Of the four index strains from infected wounds, three were indistinguishable. The carriage of similar organisms was widespread, particularly among ITU staff (72%) and patients. Ninety-one of the 296 gentamicin-resistant isolates were further investigated, and of these 33 were indistinguishable from index strains even with the use of specialized techniques. Our experience indicates that in outbreaks of infection caused by gentamicin-resistant CNS, resources should be focused on the interruption of transmission and prevention of introduction of these organisms to susceptible patients.

Bacteriological characters of strains of Staphylococcus aureus submitted to a reference laboratory related to methicillin resistance.

Methicillin-resistant Staphylococcus aureus (MRSA) strains present an increasing clinical problem. Analysis of 2679 strains submitted to a reference laboratory in the first quarter of 1983 and 3050 strains submitted in summer 1984 showed 479 and 593 multi-resistant strains. The proportion of methicillin-resistant strains classified as epidemic rose from 5.9 to 10.2%. Other methicillin-resistant strains continued to occur but other methicillin-sensitive multi-resistant strains appeared to fall. A strain with defined characters could be recognized in the Thames regions.

Toxic shock syndrome in Britain--epidemiology and microbiology.

By 30 June 1984, only 99 confirmed and probable cases of toxic shock syndrome (TSS) had been reported in the British Isles. Sixty-three were related to menstruation in women aged 14 to 54 years who used tampons of various brands and absorbencies; 33 (52%) of these cases were in girls under 20. Five women died (8%) and 19 (30%) reported at least one other possible episode. Thirty-six cases associated with a variety of clinical conditions occurred in men aged 17 to 74 years (9), women aged 20 to 54 years (15) and 12 children aged 10 months to 10 years; six patients (17%) died. Strains of Staphylococcus aureus which produced toxic shock syndrome toxin 1 (TSST-1) were isolated from 53 of 58 (91%) menstrual, but only from 18 of 33 (54%) non-menstrual patients. The frequency of toxin production was highest (93%) for 56 vaginal isolates and lowest (33%) for 9 isolates from blood culture. Ninety-six percent (68 of 71) of strains that were TSST-1-positive were sensitive to lytic-group I phages at one of the three concentrations tested; 82% were lysed by phage 29. Nineteen percent of 339 strains from a variety of sources other than TSS, produced TSST-1, and 35% of the strains lysed by group I phages were positive. Antibody to TSST-1 was detected by enzyme-linked immunosorbent assay at a serum dilution of 1:100, in 232 of 320 (82%) healthy individuals aged 14 to 56 years, but in acute-phase sera from only four of 37 (18%) TSS patients. A rise in antibody levels during convalescence was noted in two menstrual and 5 non-menstrual patients. These results show that the epidemiology of TSS is similar in Britain and the United States and provide further evidence of the importance of TSST-1-producing strains in the aetiology of the disease.

Characters of coagulase-negative staphylococci and micrococci from cases of endocarditis.

Strains of coagulase-negative staphylococci and micrococci submitted to a reference laboratory from 137 cases of endocarditis over a 5 year period were reviewed. Staphylococcus epidermidis biotype 1 (SII) was the commonest biotype in all groups of patients but exceeded 80 per cent in the 61 patients who had undergone prosthetic valve surgery and the 16 patients who had undergone other forms of surgery. Biotype 4 (SVI) was recovered from 10 of the 34 patients without surgery. Strains from prosthetic valve endocarditis were frequently resistant to many antibiotics while strains from natural valve endocarditis were frequently sensitive to all, or resistant only to penicillin. The value of bacteriophage typing was confirmed.

Staphylococci associated with toxic shock syndrome in the United Kingdom.

Only 15 cases of menstrual toxic shock syndrome were reported in the United Kingdom by 31 October 1981. The women affected used tampons of various brands. Staphylococcus aureus was isolated from the vaginas of 12 women. Two distinct strains were isolated from three women. Most strains were phage group I or nontypable strains related to them and were resistant only to penicillin, cadmium, and arsenate. Enterotoxin F was produced by strains from 10 of 12 patients and by 20% to 30% of strains from other sources--including healthy people. Its production was particularly common among control phage group I vaginal isolates. The reason for the rarity of toxic shock syndrome in the United Kingdom as compared to the United States is still unknown. There does not seem to be a low prevalence of toxigenic strains, but factors such as immunity to toxin and a difference in tampon use may be important and need further study.

Correlation of phaga type, biotype and source in strains of Salmonella typhimurium.

A series of 2092 cultures of Salmonella typhimurium isolated from human, animal and other sources in 57 countries were differentiated into 204 phage types and 19 primary and 147 full biotypes. Different biotypes belonged to the same phage type and different phage types to the same biotype, so the combination of typing methods differentiated strains more finely than either method alone: 574 different ;phage type/biotypes' were distinguished in 1937 cultures belonging to the 204 recognized phage types.The combination of biotyping with phage-typing was valuable in studying the phylogeny and spread of epidemic strains by distinguishing clones of different biotype within the same phage type and by confirming the relationship between cultures isolated from widely dispersed clones and that between cultures isolated before and after a clone had undergone variation in phage type, biotype, colicin type or antibiotic-sensitivity pattern.A widespread outbreak of infection with S. typhimurium phage type 141 in Scotland comprised independent dissemination of three clones of different biotypes, 1f, 9f and 31bd. During its epidemic spread in cattle in Britain between 1962 and 1969, another strain underwent variations in phage type (type 44 to type 29), biotype (type 26a to types 26d, 26bd, 26dgi, 26dz and 26i) and antibiotic sensitivity. A group of 275 non-fimbriate, non-inositol-fermenting and non-rhamnose fermenting (FIRN) strains, particularly associated with avian infections and thought to be clonal in origin, contained 27 phage types and 22 full biotypes in the primary biotypes 29-32.

Experiences with the typing of coagulase-negative staphylococci and micrococci.

Strains of coagulase-negative staphylococci and micrococci from many sources were biotyped and tested with a set of 20 phages, 19 of which were described by Dean et al. Strains resistant to many antibiotics were generally untypable with these phages. Nearly 50% of untypable strains could be typed by "reverse" typing--the characterisation of strains by the pattern of lysis given by their supernates on the propagating strains for the typing phages. This method was also used to clarify the relationship between isolates from an outbreak of septicaemia in a cardiac unit.