Plasmid profiles of multi-resistant Staphylococcus aureus at a children's hospital

Plasmid Analysis of 26 Staphylococcal Species by a Rapid Microscale Technique

Objective:

Evaluate a plasmid typing technique for a diverse group of staphylococci.

Design:

In vitro testing on known isolates.

Setting:

University hospital.

Intervention:

The plasmid content of 195 isolates representing 26 staphylococcal species was analyzed by agarose gel electrophoresis following lysostaphin-alkaline-SDS lysis, with and without acetone treatment.

Results:

Isolates yielded plasmid profiles with 0 to 7 extra-chromosomal bands (median, 1; 1.5); 171 (88%) had a profile with at least 1 band. Species with more than one isolate available for testing showed considerable diversity of plasmid profiles, except forStaphylococcus haemolyticus.

Conclusions:

The ease of the procedure and the diversity of plasmid profiles within each species examined suggests that plasmid profiling is an accessible and useful epidemiologic tool applicable to most staphylococcal species by epidemiologic units or clinical laboratories.

Studies on an outbreak of neonatal diarrhea caused by EPEC 0127:H6 with plasmid analysis restriction analysis and outer membrane protein determination

An outbreak of enteropathogenic Escherichia coli (EPEC) 0127:H6 diarrhea occurred at two nurseries for the newborn in Chongqing in May 1987. Sixty-nine neonates had diarrhea; two deaths resulted. The epidemic strains, carrying 1.5 and 60 Md plasmid DNA, had an identical restriction digest profile and the same outer membrane protein pattern and could produce localized adherence to HeLa, HEp-2 and FL cells. The rates of contamination with EPEC 0127:H6 on medical staff's hands in these two nurseries were 11.8% and 8.7%, respectively, whereas 85 samples from milk, air and other sources were all negative for EPEC. The source of infection was the index case's mother who had had watery stools. Transmission of EPEC 0127:H6 from infant to infant took place by way of the fecal-oral route, most likely via the hands of medical staff attending their care. We present the first case, confirmed by plasmid and restriction analyses and outer membrane protein determination, of a neonate who acquired EPEC during delivery through ingestion of organisms residing in the maternal birth canal.

Restriction enzyme analysis of plasmid DNA and bacteriophage typing of paired Staphylococcus aureus blood culture isolates

We compared restriction enzyme analysis of plasmid (REAP) DNA profiling with bacteriophage typing for determination of similarities and differences among 50 pairs of Staphylococcus aureus blood isolates from patients with multiple positive blood cultures. Isolates from 17 pairs did not have detectable plasmids. Isolates from 33 pairs had plasmids classified into 17 distinct REAP DNA profiles. Paired isolates from 31 of these episodes were identical to one another. By phage typing, 35 pairs had strong lytic reactions to a phage(s), 9 pairs lacked strong reactions, and 6 pairs consisted of a strongly reactive isolate and an isolate with no strong reaction to a phage. When consolidated into 11 general phage groups, pairs from 44 of the 50 episodes were in the same general group. REAP DNA profiles were highly reproducible (99%), whereas phage typing was not. REAP DNA profiling is superior to phage typing as a technique for determining similarities and differences among S. aureus blood isolates.

Epidemiologic study of neonatal subcutaneous gangrene caused by multi-resistant Staphylococcus aureus

Forty-five cases of neonatal subcutaneous gangrene were admitted between Nov. 1985 and Feb. 1987, with a mortality of 6.6%. This paper presents the first epidemiologic study of 20 cases of this disease caused by multi-resistant Staphylococcus aureus. Eight of 20 cases were caused by an epidemic strain belonging to phage 29 (group I) and carrying 2.8, 3.3, 4.2 and 28.5-34.0 kb plasmid DNA. The restriction endonuclease analysis confirmed that the plasmid DNA of approximately similar size in different isolates were identical or highly homologous. According to the results of an epidemiologic study the source of infection of one patient who died was her grandmother and the other one was her mother, so the family members can also be the source of neonatal infection caused by multi-resistant S. aureus.