Biomedical subjects

A Hejazi

Publications and source records attributed to A Hejazi.

3 recordsLinked to original sources

PubMed2000

Epidemiology and susceptibility of serratia marcescens in a large general hospital over an 8-year period.

Over the 8 year period 1988-1995, 1367 isolates of Serratia marcescens were isolated from 582 patients on 12 different wards of a large Dublin hospital and were particularly associated with the surgical intensive care unit. The annual incidence was over 200 isolates from 1990 to 1992 but fell to below 100 following the opening in April 1992 of a replacement surgical hospital incorporating a new intensive care unit on the same site. The most common source of S. marcescens was sputum from patients. Strain identities were determined by serotyping and phage typing at least one isolate from each of 311 of the 582 patients. The results showed that a single epidemic strain of serotype O14:K14 was present in 69% of these patients, and persisted throughout the hospital for the whole of the eight-year period. This strain was recovered from a variety of clinical specimens, including blood cultures. A minor outbreak involving a serotype O16:K28 strain also occurred and this strain also persisted from at least 1989 to 1994. Extensive surveillance failed to reveal an environmental source or faecal carriage. The likely mode of transmission appears to have been via staff hands from both symptomatic and asymptomatic patients acting as reservoirs of the organism, as has commonly been reported for this species.

Bacteriophage Typing↗

PubMed1997

Serratia marcescens.

Over the last 30 years, Serratia marcescens has become an important cause of nosocomial infection. There have been many reports concerning the identification, antibiotic susceptibility, pathogenicity, epidemiological investigations and typing of this organism. Accurate identification is important in defining outbreaks. The API 20E system has been used widely, but is not individually satisfactory. The growth of S. marcescens in the environment has been investigated in relation to water, disinfectants and plastics such as blood bags. Certain extracellular products are unique to S. marcescens. Pigment (prodigiosin) biosynthesis by S. marcescens has been investigated fully since the emergence of the organism as a cause of infection. Many other aspects of the pathogenicity and virulence of S. marcescens have been studied, including adherence and hydrophobicity, lipopolysaccharide (LPS) and extracellular products. Two modes of adhesion to host epithelial surfaces have been suggested. These are mannose-resistant (MR) pili and mannose-sensitive (MS) pili. LPS, which is responsible for the biological activity of endotoxin, has been investigated fully and 24 somatic antigens have been described. The production of different enzymes by S. marcescens as virulence factors has also been reported, including chitinase, lipase, chloroperoxidase and an extracellular protein, HasA. Antibiotics used to treat serratia infection include beta-lactam agents, aminoglycosides and fluoroquinolones and a variety of different resistance mechanisms have been demonstrated. Typing methods used to study the epidemiology of S. marcescens include biotyping, bacteriocin typing, phage typing, plasmid analysis, polymerase chain reaction amplification of enterobacterial repetitive intergenic consensus sequences (ERIC-PCR) and ribotyping. Serological typing has also been used and this method seems to be a suitable first-line typing method for S. marcescens, although some strains remain untypable. RAPD-PCR has also been applied to a small number of isolates and seems to be a promising method, especially for rapid monitoring of an outbreak and tracing the source of initial infection.

Aminoglycosides↗

PubMed1997

The use of RAPD-PCR as a typing method for Serratia marcescens.

Serratia marcescens has emerged in the last few years as an important nosocomial pathogen. Many methods for typing this organism have been described. In this study the random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) was shown to be a convenient typing method for S. marcescens. Different combinations of primers previously used for typing other gram-negative bacilli were assessed. The combination of primer HLWL-74 and 1254 gave distinguishable patterns for different serotypes and proved to be the most satisfactory. By applying this combination to 175 isolates of S. marcescens, which could be classified into 38 groups on the basis of serotyping and phage typing, 73 different RAPD patterns with good reproducibility were obtained. This is, to our knowledge, the first application of the method to a large collection of S. marcescens representing a wide range of serotypes.

Bacteriophage Typing↗