Joseph T. Parisi

Staphylococcus epidermidis: A significant nosocomial pathogen

Staphylococcus epidermidis is an organism formerly believed to be nonpathogenic. It is now recognized as a pathogen, causing infections on implanted devices and among immunosuppressed patients. Further, it has been involved in the development of resistance to a number of antibiotics. The epidemiology of this organism, its pathogenesis, and its treatment are important to infection control practitioners.

Topical Vancomycin Formulation for Methicillin-Resistant Staphylococcus epidermidis Blepharoconjunctivitis

We successfully treated two patients with severe Staphylococcus epidermidis blepharoconjunctivitis by means of a topical vancomycin hydrochloride solution (50 mg/ml) prepared with sterile water. Aqueous vancomycin preparations, however, cause significant ocular irritation probably because of low pH and osmolality values. Solutions prepared with normal saline (5 mg/ml) and phosphate-buffered artificial tears (5 mg/ml and 50 mg/ml) were significantly less irritating and possessed equivalent in vitro antimicrobial activity. Topical vancomycin should be used only when commercially available antibiotics are inadequate.

Vertebral osteomyelitis due to Staphylococcus warneri attributed to a hickman catheter

A patient with a long-term right atrial (Hickman) catheter developed vertebral osteomyelitis due to Staphylococcus warneri. Documentation of this event--to our knowledge previously unreported--was made possible by use of special studies including plasmid profiles of the coagulase-negative staphylococcal isolates.

Staphylococcus epidermidis arthritis following catheter-induced bacteremia in a neutropenic patient

Sepsis due to methicillin-resistant Staphylococcus epidermidis occurred in a neutropenic man during management with a Hickman-Broviac catheter. Despite catheter removal and 10 days of i.v. cefazolin therapy, he developed septic arthritis 6 weeks later in a nonprosthetic hip joint. S. epidermidis was isolated from the joint and found to have plasmid and phage susceptibility patterns identical to the previous blood isolate. This case is the first to document a metastatic infection from catheter-associated S. epidermidis bacteremia. It suggests that cephalosporins may not be optimal in such infections despite in vitro sensitivity. Vancomycin appears to be the drug of choice for S. epidermidis bacteremia in the neutropenic population.

Simplified method for the isolation, identification, and characterization of Staphylococcus epidermidis in epidemiologic studies

A simplified method for the isolation, identification, and characterization of Staphylococcus epidermidis from humans is described. Swabs of the nose and skin are cultured on mannitol salt agar. Isolated colonies not producing acid from mannitol (presumptive coagulase-negative staphylococci or micrococci) are then inoculated onto purple agar containing erythromycin and glycerol. All colonies growing on this medium are then replicated onto media that tests for the production of phosphatase, the production of acid from trehalose, and susceptibility to four antibiotics. All S. epidermidis sensu stricto are confirmed by the API Staph-Ident system. As a result, Staphylococcus aureus and all other coagulase-negative staphylococci are effectively identified and eliminated from further study and only strains of S. epidermidis are left for further characterization. Of the 252 isolates from 48 cultures of the nares and the fingers, 112 (44%) were eliminated during different stages of this isolation and identification procedure. The antibiotic susceptibility data further distinguished those isolates in the predominant API biochemical profile number. This scheme has applications in the early stages of either ecologic or epidemiologic studies of this important nosocomial pathogen.

Rapid method for the isolation of bacteriophages from lysogens.

A rapid method for the isolation of bacteriophages from lysogens is described. Phages are induced in broth medium containing mitomycin C, which is then replicated onto agar medium. Molten medium containing indicator strains is then poured in these plates. Bacterial lysis is subsequently detected with tetrazolium-containing broth.

Location of the coagulase gene in Staphylococcus aureus.

Evidence is presented for the chromosomal location of the coagulase determinant in most strains of Staphylococcus aureus. By the use of a pour-plate technique, transduction of the capacity to produce coagulase to a coagulase-negative mutant of S. aureus was studied. The frequencies of transduction were low unless the transducing phage was exposed to ultraviolet irradiation and the recipient was lysogenised with the transducing phage. Attempts to transfer the coagulase gene from S. aureus to S. epidermidis were not successful.