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PubMed2006

Quorum-sensing systems in staphylococci as therapeutic targets.

The staphylococci are an ever-present threat in our world, capable of causing a wide range of infections, and are a persistent presence in the clinical environment. As the number of antimicrobial compounds effective against staphylococci decreases, because of the acquisition and spread of antibiotic resistance, there is a growing need for novel therapeutic molecules. Intra and inter-species communication (quorum sensing) is a biologically significant phenomenon that has been associated with virulence, intracellular survival, and biofilm formation. Quorum sensing molecules of staphylococci and other species (e.g. Pseudomonas aeruginosa) can inhibit virulence factor production and/or growth of staphylococci, leading to the possibility that interference with staphylococcal quorum-sensing systems could be a way of controlling the diverse infections caused by the staphylococci. In this article, we discuss the potential of quorum-sensing systems of staphylococci as therapeutic targets.

Anti-Bacterial Agents↗
PubMed2004

Methicillin-resistant staphylococci isolated from animals.

Staphylococci isolated from animals (n=311) were screened for methicillin resistance by oxacillin agar screening. Oxacillin-resistant strains were tested for the presence of the mecA gene by PCR. Isolates were identified by standard techniques and 16S rDNA analysis, and their antimicrobial susceptibilities were tested using an agar diffusion method. MecA-positive strains were further analyzed using pulsed-field gel electrophoresis (PFGE). From 11 multidrug-resistant staphylococci, 6 were mecA-positive: 2 methicillin-resistant Staphylococcus aureus (MRSA) and 4 Staphylococcus haemolyticus. Screening of 300 staphylococci (100 S. aureus, 100 S. intermedius and 100 coagulase-negative staphylococci (CNS)) randomly chosen from the strain collection of the Veterinary Microbiological Diagnostic Center yielded five oxacillin-resistant coagulase-negative staphylococci, four of which were mecA-positive. PFGE showed that all mecA-positive staphylococci isolated from animals had distinct patterns. However, one MRSA isolated from a flank fistula of a dog showed homology to a human epidemic MRSA cluster, suggesting that transfer of MRSA between humans and dogs might occur.

Animal Diseases↗
PubMed2004

Isolation and characterization of subgingival staphylococci from periodontitis patients and controls.

OBJECTIVES: To isolate and characterize subgingival staphylococci from patients with periodontal disease and from periodontally healthy controls, to evaluate the periodontal environment as a potential source for systemic staphylococcal infections. METHODS: Periopaper strips were used to isolate subgingival staphylococci from 28 patients with chronic periodontitis and 28 periodontally healthy age and sex-matched controls. Staphylococci were identified by microbiological methods and antibiotic resistance profiles determined. RESULTS: Staphylococci were isolated from 54% diseased subgingival and 43% healthy subgingival sites in over 50% periodontitis patients and from 29% healthy subgingival sites in 54% controls. No significant differences in the frequency of isolation or numbers of staphylococci isolated from diseased and healthy sites were noted. Staphylococcus epidermidis was the predominant oral species. Seventy per cent (115 of 165) of all isolates were penicillin-resistant. CONCLUSIONS: Subgingival staphylococci are present in both periodontitis patients and controls. In periodontitis there is an increased risk of bacteraemia because of the increased dentogingival surface area. The dental and periodontal health of patients at risk from haematogenous infections should therefore be maintained at a high level. Antibiotic resistance profiles of the oral staphylococcal isolates suggest that amoxicillin may no longer be a suitable antibiotic for prophylaxis against systemic infections such as prosthetic valve endocarditis.

Adult↗
PubMedDate not supplied

Antimicrobial resistance in staphylococci from animals with particular reference to bovine Staphylococcus aureus, porcine Staphylococcus hyicus, and canine Staphylococcus intermedius.

Besides their role as commensals on the skin and mucosal surfaces, staphylococci may be involved in a wide variety of diseases in animals. Staphylococcal infections in animals are mainly treated with antimicrobial agents and as a consequence, staphylococci from animal sources have developed and/or acquired resistance to the respective antimicrobial agents. Resistance statistics obtained from national monitoring programmes on staphylococci from cattle and pigs, but also from surveillance studies on staphylococci involved in diseases in dogs are reported and reviewed with regard to their comparability. This review mainly focusses on the genetic basis of antimicrobial resistance in staphylococci of animal origin. Particular attention is paid to resistance to those antimicrobial agents which are most frequently used in veterinary medicine, but also to antimicrobial agents, such as chloramphenicol and mupirocin, which are used in specific cases for the control of staphylococcal infections in pets and companion animals. In addition, plasmids and transposons associated with the respective resistance properties and their ways of spreading between members of the same or different staphylococcal species, but also between staphylococci and other gram-positive bacteria, are described.

Animals↗
PubMed1957

Studies on bacteriemia. II. Further observations on the granulocytopenia induced by the intravenous injection of Staphylococci.

Intravenous injection of staphylococci produced a marked, transient granulocytopenia inrabbits. Leukopenia was rapidly followed by return of polymorphonuclear leukocytes to the peripheral blood, and normal circulating granulocyte levels were reestablished within 20 to 40 minutes. Differential arterio-venous leukocyte studies showed that polymorphonuclear leukocytes were trapped within the pulmonary vascular bed and, less constantly, in the splanchnic viscera during the initial 10 to 20 minutes following the injection of staphylococci. Granulocytes were subsequently found in larger numbers in blood leaving the lungs and splanchnic tissues, suggesting that entrapped polymorphonuclear leukocytes rapidly reentered the blood stream. This sequence of changes in circulating granulocytes was not significantly altered by splenectomy or the administration of cortisone. It has previously been shown that virtually all staphylococci in the blood stream are found within circulating polymorphonuclear leukocytes 10 to 40 minutes after the injection of culture (9). It is during this period that granulocytes return to the blood stream in large numbers. These observations suggest that staphylococci are phagocyted by polymorphonuclear leucocytes temporarily sequestered in the lungs and splanchnic viscera. It appears probable that some sequestered granulocytes containing living staphylococci subsequently return to the circulation. Such intraleukocytic staphylococci are believed to play a role in the maintenance of bacteriemia.

Agranulocytosis↗
PubMed1971

Experimental infection of the skin in the hamster simulating human impetigo. III. Interaction between staphylococci and group A streptococci.

The interaction between staphylococci and Group A beta hemolytic streptococci in mixed lesions was investigated in an experimental impetigo model. A strain of staphylococcus of phage Type 71, which has been shown in vitro to produce a bacteriocin for streptococci and other Gram-positive organisms, eliminates or reduces Group A streptococci in mixed lesions. In contrast, staphylococcal strains of phage Types 75 and 81, which do not produce a demonstrable bacteriocin in vitro, exhibit no such effect. Some variation was noted in the in vivo response of two different streptococcal M Types to the bactericidal effect of phage Type 71 staphylococci. Bacterial antagonism is more pronounced when staphylococci and streptococci are injected simultaneously into animals than when staphylococci are superimposed on preexisting streptococcal lesions. Marked variations were found in the numbers of viable streptococci (colony-forming units) recovered from individual lesions containing identical mixtures of streptococci and phage Type 71 staphylococci. The frequency of a demonstrable bactericidal effect was related to the number of streptococci injected. With small inocula of streptococci, the tendency towards an all-or-none effect was particularly striking. No evidence of selection of streptococcal or staphylococcal mutants which might explain this phenomenon was obtained. These observations suggest that the bactericidal effect of phage Type 71 staphylococci on other Gram-positive organisms, previously demonstrated in vitro, appears to operate also in vivo.

Animals↗
PubMed2005

Determining the clinical significance of coagulase-negative staphylococci isolated from blood cultures.

BACKGROUND AND OBJECTIVE: Coagulase-negative staphylococci are both an important cause of nosocomial blood-stream infections and the most common contaminants of blood cultures. Judging the clinical significance of coagulase-negative staphylococci is vital but often difficult and can have a profound impact on an institution's bloodstream infection rates. Our objective was to develop an algorithm to assist in determining the clinical significance of coagulase-negative staphylococci. DESIGN: A single experienced reviewer examined the medical records of 960 consecutive patients with positive blood cultures in a tertiary-care referral teaching hospital. Four hundred five of the cultures contained coagulase-negative staphylococci. A determination of clinical significance was made and the performances of various published algorithms that contained readily available clinical and laboratory data were compared. RESULTS: Eighty-nine (22%) of the episodes were considered significant, whereas 316 were contaminants. Patients with bacteremia were significantly more likely to be neutropenic and exhibit signs of sepsis syndrome. The algorithm with the best combined sensitivity (62%) and specificity (91%) for determining the clinical significance of coagulase-negative staphylococci was defined as at least two blood cultures positive for coagulase-negative staphylococci within 5 days, or one positive blood culture plus clinical evidence of infection, which includes abnormal white blood cell count and temperature or blood pressure. CONCLUSION: Use of this algorithm could potentially reduce misclassification of nosocomial bloodstream infections and inappropriate use of vancomycin for positive blood cultures likely to represent contamination.

Algorithms↗
PubMed2006

Epidemiological profile of linezolid-resistant coagulase-negative staphylococci.

BACKGROUND: Surveillance studies have shown that <0.1% of coagulase-negative staphylococci are linezolid resistant; however, at our institution, 4% of such organisms were found to be resistant. We investigated the risk factors for and the epidemiological profile of linezolid-resistant coagulase-negative staphylococci. METHODS: Susceptibility testing and pulsed-field gel electrophoresis were performed to analyze the genetic relatedness of both linezolid-resistant and linezolid-susceptible isolates. Clinical data were retrieved from medical records, and a case-case-control study was performed to identify unique risk factors for linezolid resistance. RESULTS: Isolates recovered from 25 patients with linezolid-resistant coagulase-negative staphylococci were examined; all but 1 of the isolates were identified as Staphylococcus epidermidis, and all but 1 had a minimum inhibitory concentration of linezolid of >256 microg/mL. Pulsed-field gel electrophoresis showed that 21 (84%) of 25 linezolid-resistant isolates exhibited genetic relatedness, whereas linezolid-susceptible isolates were of diverse clones. Unique, independent predictors of linezolid resistance included receipt of linezolid in the 3 months preceding isolation of the coagulase-negative staphylococci (odds ratio, 20.6; 95% confidence interval, 5.8-73.0). CONCLUSION: Linezolid-resistant coagulase-negative staphylococci have emerged at our institution and are predominately of a single clone. We believe that the most likely scenario to explain this emergence is that person-to-person spread of linezolid-resistant coagulase-negative staphylococci led to establishment of skin colonization with the strain. Subsequent use of linezolid was followed by selection of the linezolid-resistant strain, which then became the dominant skin flora. The potential for a parallel scenario involving clonal dissemination followed by selection of linezolid-resistant methicillin-resistant Staphylococcus aureus is a real possibility.

Acetamides↗
PubMed1997

Specific information concerning taxonomy, pathogenicity and methicillin resistance of staphylococci obtained by a multiplex PCR.

The use of DNA amplification techniques such as the polymerase chain reaction (PCR) in modern diagnostic microbiology not only allows the sensitive and specific identification of micro-organisms but also the detection of specific antibiotic resistance genes. This study describes a multiplex PCR on bacterial colonies picked directly from agar plates without preceding DNA preparation. Eubacteria and staphylococci were identified by, 16S rRNA specific PCR products. In parallel, specific primers were used for the detection of staphylococcal coa and mecA genes. This 4-h multiplex PCR, consisting of four sets of primers, was evaluated for rapid and specific differential diagnosis of methicillin-resistant and methicillin-susceptible strains of Staphylococcus aureus and coagulase-negative staphylococci. To analyse specificity of the amplification products, 100 non-staphylococcal, eubacterial isolates and 20 Candida albicans strains were tested. In a first step, specificity of all four single sets of primers was evaluated before the co-amplification within the multiplex PCR procedure was performed. The results were compared with those of conventional susceptibility and typing methods. The specific 16S rRNA PCR product for eubacterial isolates (n = 786) and staphylococci (686) was found in all strains tested. The coa gene was detected only in S. aureus (488) strains with a specificity of 100%, and was not detected in any of the coagulase-negative staphylococci (198). The mecA gene was detected in 98% of methicillin-resistant staphylococci (393) and in 2% of all methicillin-susceptible staphylococci (293). The multiplex PCR with co-amplification of different determinants provides rapid reliable information on staphylococcal identification and methicillin susceptibility supporting the diagnosis, treatment and control of staphylococcal infections.

Bacterial Proteins↗
PubMed1990

Staphylococci in human periodontal diseases.

The occurrence of subgingival staphylococci was determined in 506 individuals with advanced adult periodontitis, 108 with early-onset periodontitis, 13 with localized juvenile periodontitis, 18 with gingivitis, and 13 with 20 failing osseointegrated titanium dental implants. Subgingival samples were collected with paper points and transported in VMGA III. The bacterial samples were plated on Staphylococcus 110 medium which was incubated in 10% CO2, and on enriched brucella blood agar, which was incubated anaerobically. Staphylococcal isolates from 94 adult periodontitis subjects were speciated using the API STAPH Trac micromethod kit system and the Bacto Staph latex agglutination test for coagulase activity. Staphylococcus epidermidis comprised 45.8% and Staphylococcus aureus 22.3% of total staphylococcal isolates. At 1 microgram/ml, in vitro resistance by staphylococci was found to tetracycline (14.4% of isolates), penicillin (4.9%), erythromycin (12.1%), and metronidazole (31.9%). Subgingival staphylococci were isolated from approximately 50% of gingivitis and periodontitis patients. No statistically significant differences were found between these patient groups in the prevalence or mean proportions of staphylococci recovered. "Periimplantitis" lesions exhibited significantly higher proportions of staphylococci (15.1%) than gingivitis (0.06%) or periodontitis (1.2%) lesions. Staphylococci may play a role in some failing osseointegrated dental implants.

Adolescent↗
PubMed1991

Activity of new quinolones against ciprofloxacin-resistant staphylococci.

Because of the development of newer fluoroquinolones with improved activity against gram-positive organisms, we elected to compare the inhibitory properties of ofloxacin, temafloxacin, sparfloxacin, PD131628, PD127391, and WIN57273 against 105 ciprofloxacin-resistant staphylococci. Based on comparison of MICs for 90% of the organisms (MIC90s), WIN57273 was the most active agent against oxacillin-resistant Staphylococcus aureus; the MIC90 was 0.5 microgram/ml. Against oxacillin-resistant, coagulase-negative staphylococci, PD127391 and WIN57273 were the most active agents; the MIC90 was 0.5 microgram/ml. Against isolates of staphylococci for which ciprofloxacin MICs were greater than or equal to 32 micrograms/ml, WIN57273 and PD127391 still exhibited high activity, inhibiting 100 and 95% of the isolates, respectively, at 2 micrograms/ml. The spontaneous mutation rates for ciprofloxacin-susceptible staphylococci were lowest for ofloxacin. The frequency of spontaneous mutations of ciprofloxacin-resistant staphylococci was low; however, the MICs of PD127391 and WIN57273 for these mutant isolates were greater than 2 micrograms/ml. WIN57273 and PD127391 are two potent new quinolones with high levels of activity against highly ciprofloxacin-resistant staphylococci. There is, however, a major concern of selection of spontaneous mutants resistant to these newer agents.

Anti-Infective Agents↗
PubMed1999

Distribution of genes encoding resistance to macrolides, lincosamides, and streptogramins among staphylococci.

The relative frequency of 10 determinants of resistance to macrolides, lincosamides, and streptogramins was investigated by PCR in a series of 294 macrolide-, lincosamide-, and/or streptogramin-resistant clinical isolates of Staphylococcus aureus and coagulase-negative staphylococci isolated in 1995 from 32 French hospitals. Resistance was mainly due to the presence of ermA or ermC genes, which were detected in 259 strains (88%), in particular those resistant to methicillin (78% of the strains). Macrolide resistance due to msrA was more prevalent in coagulase-negative staphylococci (14.6%) than in S. aureus (2.1%). Genes related to linA/linA' and conferring resistance to lincomycin were detected in one strain of S. aureus and seven strains of coagulase-negative staphylococci. Resistance to pristinamycin and quinupristin-dalfopristin was phenotypically detected in 10 strains of S. aureus and in three strains of coagulase-negative staphylococci; it was always associated with resistance to type A streptogramins encoded by vat or vatB genes and occurred in association with erm genes. The vga gene conferring decreased susceptibility to type A streptogramins was present alone in three strains of coagulase-negative staphylococci and in combination with erm genes in 10 strains of coagulase-negative staphylococci. A combination of vga-vgb-vat and ermA genes was found in a single strain of S. epidermidis.

Anti-Bacterial Agents↗
PubMed1964

CHARACTERISTICS OF METHICILLIN-RESISTANT STAPHYLOCOCCI.

Sutherland, R. (Beecham Research Laboratories Ltd., Betchworth, Surrey, England), and G. N. Rolinson. Characteristics of methicillin-resistant staphylococci. J. Bacteriol. 87:887-899. 1964.-Cultures of naturally occurring methicillin-resistant staphylococci obtained from a number of hospitals were examined for the nature and degree of resistance to methicillin and other antibiotics. All the cultures tested were similar in that they consisted of mixed populations in which the majority of cells were of normal sensitivity to methicillin with a minority showing methicillin resistance. The resistant members also differed from the rest of the population in that they grew more slowly even in the absence of methicillin. Pure cultures of the resistant minority were obtained readily but, on repeated transfer in the absence of methicillin, resistance was lost and the cultures reverted to mixed populations similar to the original naturally occurring strains. When methicillin-sensitive staphylococci were repeatedly subcultured in the presence of methicillin, a mixed population was obtained in which only a minority of cells were resistant to the antibiotic; in this respect, the cultures of methicillin-resistant staphylococci selected in vitro resembled the naturally occurring strains. The original cultures of methicillin-resistant staphylococci comprised populations of cells with uniform sensitivity or insensitivity to other antibiotics. The resistance of these staphylococci to methicillin was not due to increased ability to inactivate the drug but to intrinsic insensitivity to methicillin.

Anti-Bacterial Agents↗
PubMed1966

Bacteriostatic activity of serum against staphylococci.

Cybulska, Janina (State Institute of Hygiene, Warsaw, Poland), and J. Jeljaszewicz. Bacteriostatic activity of serum against staphylococci. J. Bacteriol. 91:953-962. 1966.-Antistaphylococcal activity of normal serum against strains exhibiting various patterns of coagulase, clumping-factor, and staphylokinase production is not connected with the presence of these factors. Purified coagulase does not influence this property of serum. Coagulase-negative strains with clumping-factor activity grow in normal serum as typical pathogenic staphylococci. Serum bacteriostatic activity against staphylococci may be reversed by several nonspecific factors, such as sterile broth, supernatant fluids of coagulase-negative strains, and ammonium sulfate precipitates of culture supernatant fluids of various staphylococci. Immune sera with a high agglutinating titer for staphylococcal cells do not prevent growth of serum-resistant strains; serum-susceptible strains are inhibited as in normal serum control. Activation or blocking of the serum fibrinolytic system does not influence serum bacteriostatic activity. The growth rate of serum-resistant strains is identical in serum and in Todd-Hewitt broth; serum-susceptible strains are inhibited to the inoculum level, but decreases and increases in viable count are noted during a 24-hr observation period. Observations made with sera of 10 animal species clearly demonstrated differences in serum bacteriostatic activity, mouse serum being completely noninhibitory and cat serum only weakly inhibitory. The technique of quantitative determination of serum susceptibility of staphylococci is described, and the importance of serum antistaphylococcal activity in vitro is discussed. Experimental staphylococcal infection produced in rabbits by intravenous injection of different Staphylococcus aureus strains did not result in significant changes in serum antistaphylococcal activity. The technique of experimental infection used caused chronic infection, with a peak on the 14th day; this was proved by means of a newly developed 5'-nucleotidase test. At the same time, sera of infected animals exhibited slight inhibitory properties, which returned to initial values 1 week later. Infection was produced by strains recognized as nonpathogenic and was inhibited in vitro by sera from both normal and infected rabbits. It is concluded that antistaphylococcal activity of serum should be considered as an "in vitro" phenomenon, which seems to have no importance in defense mechanisms of rabbits infected intravenously with staphylococci.

Animals↗
PubMed1980

Simplified lyogroup system, a new method for routine identification of staphylococci: description and comparison with three other methods.

A simplified system for routine identification of the six lyogroups of human staphylococci is described. The method is based on the determination of the lytic activity on five different test media and of the phosphatase activity of each isolate. A total of 689 staphylococci isolated from clinical material over a 6-month period were identified according to this simplified system. The same strains were identified in parallel using three other methods designed for routine identification of staphylococci: the Kloos and Schleifer abbreviated scheme (J Clin. Microbiol. 1:82-88, 1975) the scheme proposed by the Subcommittee on the Taxonomy of Staphylococci and Micrococci (Int. J. Syst. Bacteriol. 26:332-334, 1976), and the API STAPH micromethod. Isolated whose identification was in disagreement were identified on a taxonomic level according to the extensive classification scheme of Schleifer and Kloos. In addition, 42 reference staphylococci of known identity were reidentified using the simplified lyogroup system as well as the three other routine methods. The results of this comparative study was detailed and discussed. A primary advantage of the simplified lyogroup system is that it also provides separation of staphylococci from micrococci, which must be performed separately when the other methods are used. Other significant advantages concerned with reliability, speed, and practicality are shown.

Bacteriological Techniques↗
PubMed1988

Characteristics of coagulase-negative staphylococci that help differentiate these species and other members of the family Micrococcaceae.

One hundred reference strains and 1,240 clinical isolates representing 26 species of the family Micrococcaceae were used to evaluate the potential of tests for synergistic hemolysis, adherence to glass, pyroglutamyl-beta-naphthylamide hydrolysis, and susceptibility to a set of five antimicrobial agents for differentiating these species and strains within the species. Sixty-eight percent of the clinical isolates exhibited synergistic hemolysis; 69% of the clinical staphylococci but none of the micrococci or stomatococci were adherence positive, and 92% of the strong positive adherence reactions were produced by strains of Staphylococcus epidermidis. Strains from 15 of the species were pyroglutamyl-beta-naphthylamide positive, but this test separated Staphylococcus xylosus from other novobiocin-resistant staphylococci and Staphylococcus intermedius from other coagulase-positive species. A polymyxin B disk helped differentiate S. epidermidis from most other coagulase-negative staphylococci, and a bacitracin disk (10 U) helped differentiate Staphylococcus haemolyticus from most other novobiocin-susceptible staphylococci. All strains that were susceptible to furazolidone and resistant to Taxo A disks (bacitracin, 0.04 U; BBL Microbiology Systems, Cockeysville, Md.) were staphylococci. We observed a 91% correlation between species identification obtained with the Staph-Ident system (Analytab Products, Plainview, N.Y.) and conventional methods; but the micrococci and stomatococci were incorrectly identified as staphylococci with Staph-Ident, and several isolates of S. epidermidis were misidentified as Staphylococcus hominis because they were alkaline phosphatase negative. Both these problems can be prevented by adding the simple tests we describe to those already recommended when the Staph-Ident system is used to identify isolates of gram-positive, catalase-positive cocci.

Bacitracin↗
PubMed2002

Rapid detection of methicillin-resistant staphylococci from blood culture bottles by using a multiplex PCR assay.

Rapid detection and accurate identification of methicillin-resistant staphylococci are critical for the effective management of infections caused by these organisms. We describe a multiplex PCR-based assay for the direct detection of methicillin-resistant staphylococci from blood culture bottles (BacT/Alert; Organon-Teknika, Durham, N.C.). A simple lysis method followed by a multiplex PCR assay designed to detect the nuc, mecA, and bacterial 16S rRNA genes was performed. A total of 306 blood culture specimens were collected over a period of 10 months from June 1998 to April 1999, consisting of 236 blood cultures growing staphylococci (including 124 methicillin-resistant Staphylococcus spp.), 50 positive blood cultures which grew organisms other than staphylococci, and 20 blood cultures that were negative for bacterial and fungal pathogens after 5 days of incubation and terminal subculture. DNA extraction, PCR, and detection could be completed in 2.5 h. Of the positive blood cultures with staphylococci, the multiplex PCR assay had a sensitivity and specificity of 99.2% and 100%, respectively. Our results show that rapid, direct detection of methicillin-resistant staphylococci is possible, allowing clinicians to make prompt and effective decisions for the management of patients with staphylococcal bacteremia.

Bacteremia↗
PubMed2002

DNA fingerprinting analysis of coagulase negative staphylococci implicated in catheter related bloodstream infections.

AIMS: The epidemiological assessment of cases of coagulase negative staphylococcal catheter related bloodstream infection. METHODS: Two hundred and thirty patients with suspected catheter related bloodstream infection were evaluated over a two year period. Central venous catheters were cultured both endoluminally and extraluminally. Peripheral blood, catheter hubs, skin entry, and skin control sites were also cultured. Pulsed field gel electrophoresis (PFGE) was used to DNA fingerprint coagulase negative staphylococci isolated from patients with presumptive catheter related bloodstream infection. RESULTS: Sixty cases of catheter related bloodstream infection were identified, 21 of which were attributed to coagulase negative staphylococci. Two hundred and ninety four separate isolates of coagulase negative staphylococci from the 21 cases of catheter related bloodstream infection were subjected to PFGE (mean of 14 for each case). Catheter related bloodstream infection was only confirmed by PFGE analysis in 16 of the 21 cases because in the remaining five cases peripheral blood and central venous catheter coagulase negative staphylococci isolates were different. Skin entry, control skin, and central venous catheter hub isolates matched peripheral blood isolates in six, four, and seven cases, respectively. Coagulase negative staphylococci isolates could not be cultured from the patients' own skin in seven cases of catheter related bloodstream infection. Central venous catheter lumens were colonised in all cases of catheter related bloodstream infection compared with 44-81% of cases that had positive external surface catheter tip cultures, depending on the threshold used to define significant growth. CONCLUSIONS: Catheter related bloodstream infection as a result of coagulase negative staphylococci may be over stated in about a quarter of cases, unless a discriminatory technique is used to fingerprint isolates. No single, simplistic route of bacterial contamination of central venous catheters was identified, but endoluminal catheter colonisation is invariably present in cases of catheter related bloodstream infection.

Bacteremia↗