Colonization priority among Staphylococcus aureus strains--correlation with phage-type

Phage types and antimicrobial resistance among Danish bovine Staphylococcus aureus isolates since the 1950s

A total of 292 bovine Staphylococcus aureus isolates obtained from the 1950s (86 isolates), 1992 (107 isolates), and 2000 (99 isolates) were examined for antimicrobial susceptibility and phage typing. The same types of S. aureus (80, 52, 3A, 3A/3C, 42E, 77) were found among the isolates from all three time periods, representing 43.3% of the typeable isolates. This indicates that the Danish S. aureus population related to bovine mastitis has remained relatively unchanged over the last 50 years. The occurrence of antimicrobial resistance has remained low in Denmark in comparison to other countries in Europe.

What's new in burn microbiology? James Laing Memorial Prize Essay 2000

A variety of factors contribute to the development of infection in burned patients. The role of wound management procedures, risk factors associated with infection, typical bacterial pathogens and associated exotoxins, current problems with antibiotic resistance, wound sampling and rare complications of infection are described. The use of new novel treatments that are currently being developed, such as cell signalling molecules and the increasing use of natural antimicrobial agents, for example honey, papaya fruit and tea-tree oil are discussed. The impact of new methods for earlier detection of infectious agents that could change future practices in burn care is also described.

A comparison of antimicrobial resistance rates in Gram-positive pathogens isolated in the UK from October 1996 to January 1997 and October 1997 to January 1998

Rates of resistance for two consecutive years for 28 centres (10 Teaching, nine Associate Teaching and nine District General hospitals) in the UK were compared. Combined rates of resistance for each of the hospital types of Staphylococcus aureus to methicillin revealed an increase in the rate of resistance in Teaching hospitals (12.5% year 1, 23.5% year 2), but, for Associate Teaching and District General hospitals rates fell (Associate Teaching 19.1% year 1, 11.9% year 2; District General 16.5% year 1 and 11.3% year 2). Using conventional methodology to determine MICs, no strain was considered to have reduced susceptibility to vancomycin. Among coagulase-negative staphylococci, increased resistance was observed for Staphylococcus epidermidis to rifampicin, for Staphylococcus haemolyticus to clindamycin, for Staphylococcus saprophyticus to penicillin and for Staphylococcus spp. to clindamycin, methicillin and rifampicin. For Streptococcus pneumoniae an upward trend in low-level resistance to penicillin was observed (18 of the 28 centres), however, for high-level resistance the trend was in the opposite direction (only four centres showed an increase). For Enterococcus faecalis there was a trend to a fall in levels of resistance, the only exception being an increase in high-level gentamicin resistance (10.5% year 1, 15.1% year 2, P = 0.0388). For Enterococcus faecium rates of resistance were not significantly different except for increases in resistance to nitrofurantoin and rifampicin.

Staphylococcus aureus strains of type 95. Spread of a single clone

Staphylococcus aureus strains of type 95 in Denmark have increased to a frequency of 20% of the total S. aureus population. A clonal origin and possible subdivision of these strains have been discussed. In the present investigation 35 epidemiologically unrelated S. aureus strains of type 95 as well as reference strains of other types have been analysed by other typing techniques including lectin-typing, multilocus enzyme electrophoresis and pulsed-field gel electrophoresis of genomic restriction fragments. No subdivision could be achieved based on any of these methods and a clonal origin seems therefore possible.

An outbreak of infection due to Staphylococcus aureus phage type 52 in a neonatal intensive care unit

An outbreak of infection due to Staphylococcus aureus phage-type 52, resistant only to penicillin, occurred in children's wards primarily in a neonatal intensive care unit. The outbreak involved 86 infants; the majority presented with conjunctivitis, wound infections, boils, omphalitis and otitis externa. Seven per cent of these infants (six of 86) also had septicaemia. In addition, 6% (five of 86) were colonized by this phage type and the most common site of carriage was the umbilicus. The outbreak was contained by eradication of nasal carriage among the staff members and also by standard infection control measures.

Catheter-related Staphylococcus aureus infections

Among 3394 patients with Staphylococcus aureus bacteraemia from the years 1986-89, 88 patients were found whose intravenous catheter and blood grew organisms of the same phage type. Strains of phage type 95 were more frequent among the patients with confirmed catheter-related bacteraemia than among other bacteraemia cases. Strains with particular phage-type patterns occurring with increasing frequency in Denmark during recent years also occurred with significantly higher frequencies among the confirmed catheter-related bacteraemias. No major differences in antibiotic resistance were observed. Patients with catheter-related bacteraemia had, in spite of a higher frequency of underlying diseases, a lower mortality compared with other bacteraemia patients, and endocarditis occurred less frequently (2% vs. 6%). Among 201 S. aureus isolates from catheters in 1988 only strains of group I occurred with increased frequency. The possible role of catheters as selection pressure on the S. aureus population is discussed.

Spread of Staphylococcus aureus strains of phage-type 95 in Denmark 1968–1989

The spread of Staphylococcus aureus strains of phage-type 95 was traced retrospectively in Denmark by the review of more than 15,000 S. aureus bacteraemia isolates (1957-88) and from data collected by phage-typing of c. 260,000 isolates from all body sites (1977-89). The first two type 95 strains had been isolated from blood in 1968, and after an interval of 3 years there was a steady increase of bacteraemia strains all over Denmark. From 1977 to 1989 the incidence of type 95 strains among isolates from all body sites increased from 3.8 to 18.8%. Different patterns of increase were recorded in 13 major hospitals and in various clinical departments of two hospitals and these were further analysed. Conjunctival swabs gave the highest percentage of type 95 strains and those from abscesses gave the lowest percentage. Of the type 95 bacteraemia strains 90.4% were resistant to penicillin, but neither methicillin nor gentamicin resistance was recorded.

Outbreaks of infection with methicillin-resistant Staphylococcus aureus on neonatal and burns units of a new hospital

Multiple introductions of methicillin-resistant Staphylococcus aureus (MRSA) strains occurred to a new hospital in Hong Kong. Two years of clinical microbiological surveillance of the resulting outbreaks was combined with laboratory investigation by phage and antibiogram typing, and plasmid profiling. The outbreaks on the special care baby (SCBU) and burns (BU) units were studied in detail, and colonization of staff and contamination of the environment were investigated. MRSA were spread by the hands of staff on the SCBU, where long-term colonization of dermatitis was important, but were probably transmitted on the BU by a combination of the airborne, transient hand-borne and environmental routes. Simple control measures to restrict hand-borne spread on the SCBU were highly effective, but control was not successful on the BU.