Persistent bacteremia due to coagulase-negative staphylococci in low birth weight neonates.

During a 6-month period in 1987, 13 low birth weight neonates without indwelling central intravascular catheters had persistent (positive blood cultures for greater than or equal to 6 days) coagulase-negative staphylococcal bacteremia despite adequate antibiotic therapy. Daily blood cultures remained persistently positive for a mean of 13 days (range 6 to 25 days). This group of infants was compared with other low birth weight infants with similar birth weights and nonpersistent coagulase-negative staphylococcal bacteremia, defined as two or more positive blood cultures accompanied by supporting clinical manifestations of sepsis. During this period, coagulase-negative staphylococcal represented 29% of all bacteremias, and 33% of coagulase-negative staphylococcal bacteremias were persistent. Other than soft tissue abscesses, none of the infants with persistent coagulase-negative staphylococcal bacteremia had a defined focus of infection. Abdominal distention (P = .001) and thrombocytopenia (P less than .03) occurred significantly more frequently in the patients with persistent coagulase-negative staphylococcal bacteremia than in those with nonpersistent bacteremia. Of the 13 patients with persistent coagulase-negative staphylococcal bacteremia, 2 received methicillin and 11 received vancomycin. No antibiotic tolerance to either antibiotic could be demonstrated. Serum concentrations of vancomycin far exceeded the minimum bactericidal concentration in all cases in which vancomycin was prescribed. No in vitro differences could be demonstrated between persistent and nonpersistent coagulase-negative staphylococcal strains for slime production, biotype, proteins from modified whole cell lysates developed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and opsonophagocytosis by adult neutrophils in the presence of pooled human sera. Additionally, plasmid profile analysis and phage typing revealed no common strain causing the persistent bacteremia.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

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.

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.

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.

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.

Characterization of the tobramycin-kanamycin-neomycin resistance plasmid in Staphylococcus epidermidis.

A strain of Staphylococcus epidermidis was transduced to tobramycin resistance and all transductants were also resistant to kanamycin and neomycin. Results of curing studies also indicated that these resistances were controlled by a single determinant on a plasmid. Agarose gel electrophoresis of the plasmid DNA from parent, cured, and transduced strains showed a single plasmid was responsible and its molecular weight was calculated to be 2.85 x 10(6). Attempts to determine other properties of the organism controlled by this plasmid were unsuccessful.

Significance of chromogenic variants in studies of virulence factors of Staphylococcus aureus.

Parisi, Joseph T. (Duquesne University, Pittsburgh, Pa.). Significance of chromogenic variants in studies of virulence factors of Staphylococcus aureus. J. Bacteriol. 92:589-591. 1966.-Large numbers of chromogenic variants were isolated from cultures of a parent strain of Staphylococcus aureus growing in Brain Heart Infusion (Difco). The parent strain and four selected chromogenic variants were tested for either quantitative or qualitative differences in the production of extracellular substances associated with virulence. Quantitative differences were found in the ability of these strains to produce coagulase and hyaluronidase, whereas qualitative differences were found in the production of plate hemolysins, bound coagulase, opacity in an egg yolk medium, and a proteinase. In view of the rate and extent of the occurrence of these chromogenic variants, their presence in an inoculum could lead to inaccurate results in in vitro studies of staphylococcal virulence.

Nucleotide sequence of the constitutive macrolide-lincosamide-streptogramin B resistance plasmid pNE131 from Staphylococcus epidermidis and homologies with Staphylococcus aureus plasmids pE194 and pSN2.

The complete nucleotide sequence of the Staphylococcus epidermidis plasmid pNE131 is presented. The plasmid is 2,355 base pairs long and contains two major open reading frames. A comparison of the pNE131 DNA sequence with the published DNA sequences of five Staphylococcus aureus plasmids revealed strong regional homologies with two of them, pE194 and pSN2. The region of pNE131 containing the reading frame which encodes the constitutive ermM gene is almost identical to the inducible ermC gene region of pE194, except for a 107-base-pair deletion which removes the mRNA leader sequence required for inducible expression. A second region of pNE131 contains an open reading frame with homology to the small cryptic plasmid pSN2 and potentially encodes a 162-amino-acid protein.

Naturally occurring Staphylococcus epidermidis plasmid expressing constitutive macrolide-lincosamide-streptogramin B resistance contains a deleted attenuator.

A naturally occurring constitutive macrolide-lincosamide-streptogramin B (MLS) resistance plasmid, pNE131, from Staphylococcus epidermidis was chosen to study the molecular basis of constitutive expression. Restriction and functional maps of pNE131 are presented along with the nucleotide sequence of ermM, the gene which mediates constitutive MLS resistance. Sharing 98% sequence homology within the 870-base-pair Sau3A-TaqI fragment, ermM appears to be almost identical to ermC, the inducible MLS resistance determinant from S. aureus (pE194). The two genes share nearly identical sequences, except in the 5' promoter region of ermM. Constitutive expression of ermM is due to the deletion of 107 base pairs relative to ermC; the deletion removes critical sequences for attenuation, resulting in constitutive methylase expression.

Phage typing of Staphylococcus epidermidis.

Thirteen phages were isolated from lysogenic cultures of Staphylococcus epidermidis from a clinical laboratory and used to type 223 clinical isolates of this organism. The 18 phages isolated in The Netherlands were used to type these same cultures. No correlation was observed between phage type, biotype, or clinical source of isolation. At phage concentrations of 100 times the routine test dilution, 35.0% of the cultures were typable with out phages and 21.5% were typable with the phages from The Netherlands. When only cultures in biotype 1 were considered, 43.3 and 24.1% of 141 cultures were typable with our phages and those from The Netherlands, respectively. The lytic reactions obtained with our phages were generally stronger and easier to read and the lytic patterns were, almost invariably, shorter. The typability of untypable cultures was increased 12.0% by incubation at 45 C prior to phage typing and 20% by heat shock (55 C for 5 min) prior to typing. Phage typing 5 subcultures of 20 typable cultures on 5 successive days showed that the lytic patterns were reproducible. The present status of phage typing S. epidermidis and the work needed to obtain a set of typing phages for epidemiological studies of infections by this organism are discussed.

Improved rapid plate method for the isolation of bacteriophages from lysogenic bacteria.

A modification of a recently reported rapid plate method for the isolation of bacteriophages from lysogenic bacteria is described. The velveteen replica plate technique was used for inoculation of mitomycin C-induced colonies onto agar plates, and tetrazolium chloride was used to enhance detection of phage activity on replicated indicator plates.

Bacteriophage typing of coagulase-negative staphylococci.

Cultures comprising the 10 species of coagulase-negative staphylococci proposed by Kloos and Schleifer (J. Clin. Microbiol. 1:82--88, 1975) were typed with bacteriophages isolated from Staphylococcus epidermidis. Although only 10.5% were typable, 50% of those identified as S. epidermidis were typed. Cultures from patients with middle ear infections were also classified by this system and phage typed.