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PubMed1986

Viability of staphylococci in various diluents.

Standardized suspensions of 78 staphylococci and micrococci were stored in different diluents and tested periodically for 3 weeks to determine their ability to maintain viability. In 92% of the tests, diluent suspensions yielded viable organisms for at least 21 days. Organism survival was maintained in the following order, from best to worst: skim milk, tap water, 0.9% NaCl, deionized water, Dianeal (peritoneal dialysis) fluid, 0.2% bovine serum albumin and 5% glycerol. In 81% of the instances, oxacillin-susceptible staphylococci survived better than oxacillin-resistant staphylococci.

Animals↗
PubMed1989

Prevalence of peritonitis-associated coagulase-negative staphylococci on the skin of continuous ambulatory peritoneal dialysis patients.

The predominance of coagulase-negative staphylococci as normal skin flora is thought to be a factor in their association with episodes of peritonitis in patients undergoing continuous ambulatory peritoneal dialysis. We investigated the prevalence of peritonitis-associated strains on the skin of 28 patients undergoing peritoneal dialysis. Coagulase-negative staphylococci were the most frequently isolated organisms, comprising 47% of peritoneal dialysis fluid isolates and 59% of body site isolates. A total of 142 coagulase-negative staphylococci were speciated, tested for their antimicrobial sensitivity and slime production, and identified by phage typing and plasmid-profile analysis. Staphylococcus epidermidis was the most commonly identified species from both peritoneal dialysis fluid (73%) and body sites (53%). Multiple antibiotic resistance was common, and the greater proportion of isolates were resistant to methicillin; 63.6% of peritoneal dialysis fluid isolates and 61.7% of body-site isolates. S. haemolyticus isolates were significantly more resistant to methicillin than other species. By phage typing and plasmid-profile analysis it was shown that peritonitis was rarely caused by skin-colonizing strains. In only 3 of 14 patients were peritonitis-associated strains isolated as skin colonizers, and no patients developed peritonitis due to organisms previously isolated as skin colonizers.

Bacteriophage Typing↗
PubMed1999

Comparative study of staphylococci from the skin of atopic dermatitis patients and from healthy subjects.

BACKGROUND: Bacterial infections occur frequently on the skin of atopic dermatitis (AD) patients. The objectives of this study were to evaluate the microbiology of the skin of AD patients for staphylococci, the frequency and density of each species, and their susceptibility to antimicrobial drugs. METHODS: To study the staphylococci present on the skin of 21 AD outpatients and of 12 healthy subjects (HS), cutaneous organisms were obtained using the contact-plate method. RESULTS: Staphylococcus aureus was isolated in 85.7% of AD patients (mild type, 77.8%; moderate type, 87.8%; and severe type, 100%) and in 25% of HS, while Staphylococcus epidermidis was isolated in 83.3% of HS and in 38.1% of AD patients. Among the coagulase-negative staphylococci (CNS) identified, S. epidermidis was the common type and several other CNS were detected in both AD patients and HS. As the eruption grade of dermatitic skin became more severe, the average density of S. aureus increased (severe, 2.68 +/- 0.86; moderate, 2.49 +/- 0.48; mild, 2.28 +/- 0.44). A reversed tendency was seen in S. epidermidis (severe, 1.80; moderate, 1.90; mild, 2.10). Among nine antimicrobial drugs tested against S. aureus, S. epidermidis, and some other types of CNS isolates, vancomycin (VCM) and minocycline (MINO) were the most active, gentamycin (GM) was the less active, and ampicillin (ABPC) was the least active. CONCLUSIONS: The skin of AD patients was more frequently colonized with S. aureus than that of normal controls. As the severity of the AD lesions increased, the numbers of S. aureus isolated increased. The skin of HS was more colonized with S. epidermidis. Other species of CNS were isolated from several cases of AD patients and HS. In addition, S. aureus, S. epidermidis, and the other CNS showed poor susceptibility to some of the tested antimicrobial drugs.

Adolescent↗
PubMed2000

Clonal spread of staphylococci among patients with peritonitis associated with continuous ambulatory peritoneal dialysis.

BACKGROUND: Peritonitis is the most important complication of continuous ambulatory peritoneal dialysis (CAPD). Coagulase-negative staphylococci (CNS) are the most common causes of peritonitis, only limited information is available regarding the distribution and epidemiology of different CNS species associated with CAPD peritonitis. METHODS: CNS isolated from dialysis effluent from CAPD patients with peritonitis was identified by species and further analyzed with pulsed-field gel electrophoresis (PFGE). RESULTS: A total of 216 microorganisms (206 bacteria and 10 Candida species) were isolated from 196 consecutive culture-positive CAPD samples obtained from 75 patients. One hundred and twenty-one (56%) isolates represented staphylococci. The four most frequently isolated staphylococcal species were Staphylococcus epidermidis (70 isolates), Staphylococcus aureus (31 isolates), Staphylococcus hemolyticus (10 isolates), and Staphylococcus hominis (4 isolates). PFGE analysis revealed the clonal spread among patients of three different clones of S. epidermidis and one clone of S. aureus among the investigated patients. Indistinguishable isolates of either S. epidermidis, S. hominis, or S. aureus were also isolated in repeated samples from several patients. CONCLUSION: PFGE is a useful method for the epidemiological evaluation of staphylococci-associated CAPD infections and should replace older and less accurate methods, such as antibiotic sensitivity patterns. We recommend that CNS isolates from patients with CAPD-associated peritonitis should be saved for future investigations and typing, which would aid in the management of this patient category.

Ascitic Fluid↗
PubMed2000

Predominant staphylococci in the intensive care unit of a paediatric hospital.

Coagulase-negative staphylococci cause a significant number of infections, especially in immunocompromised patients, including premature neonates. Nosocomial strains present in the environment create a special risk.We studied staphylococci isolated from the intensive care unit of a paediatric teaching hospital over the period of six months in 1997. Biotyping and species identification were performed; resistance to methicillin and other beta-lactam antibiotics and patterns of resistance to antimicrobial agents were determined. Staphylococcus cohnii was the predominant species of 147 isolates of staphylococci recovered from the ward environment. Strains were resistant to several antibiotics and 97% were resistant to methicillin. In isolates from infants (72) methicillin-resistant strains of Staphylococcus epidermidis were predominant. Susceptibility to beta-lactams (penicillin, amoxycillin, amoxycillin-clavulanic acid and cephalosporins: cephalothin, cefuroxime and cefotaxime) showed differences between the two species. Some S. cohnii were susceptible to penicillin and amoxycillin despite methicillin-resistance. S. epidermidis were relatively susceptible to amoxycillin-clavulanic acid and cephalosporins. All strains investigated were susceptible to vancomycin, but nearly 30% demonstrated high-level resistance to mupirocin. The search for strains of the same origin showed clones belonging to S. epidermidis, S. hominis and S. saprophyticus but not S. cohnii.A large number of multiresistant, phenotypically different S. cohnii strains surviving in the ward environment may provide a reservoir of antimicrobial resistance genes.

Bacterial Typing Techniques↗
PubMed2003

Survey of nasal colonization by, and assessment of a novel multiplex PCR method for detection of biofilm-forming methicillin-resistant staphylococci in healthy medical students.

We surveyed the prevalence of nasal colonization by biofilm-forming methicillin-resistant staphylococci in healthy medical students, who had never had contact with patients, using polymerase chain reaction (PCR) to detect themec A gene, production of penicillin-binding protein 2' (PBP2'), and quantitative assay of biofilm formation on polystyrene. Anterior nasal swabs from 90 students were cultured on mannitol salt and oxacillin salt screening agar plates. In total, 231 staphylococcal isolates belonging to 10 species from 88 students were identified, of which 139 from 77 (88%) students were Staphylococcus epidermidis. The overall prevalences of methicillin-resistant and biofilm-forming staphylococci were 48% (43 of 90) and 59% (53 of 90) for the medical students, respectively. In total 30 (33%) students carried biofilm-forming methicillin-resistant staphylococci in the nares, all of which were identified as S. epidermidis. For rapid detection of biofilm-forming methicillin-resistant S. epidermidis (MRSE), we devised a novel multiplex PCR method to assess a total of 243 staphylococcal isolates, including the 231 isolates from the students. The multiplex PCR assay used six primers to amplify atl E and ica ADB, which are responsible for the biofilm formation ofS. epidermidis, and mec A genes. The multiplex PCR assay revealed that 68 (96%) isolates were detectable in 71 biofilm-forming MRSE isolates, which corresponded to 93% (28 of 30) of biofilm-forming MRSE carriers. Surveillance of nasal colonization with biofilm-forming MRSE using this multiplex PCR in healthcare workers and patients, might provide useful information for the establishment of infection control procedures toward biofilm-forming MRSE.

Adult↗
PubMed2001

Seven cases of surgical native valve endocarditis caused by coagulase-negative staphylococci: An underappreciated disease.

BACKGROUND: Native valve endocarditis caused by coagulase-negative staphylococci is uncommon and the diagnosis is infrequently considered. The disease, however, appears to be increasing in frequency and can pursue an aggressive clinical course. We report the clinical features of 7 cases of coagulase-negative staphylococcal native valve endocarditis (CNS-NVE) seen at 1 institution with a large cardiovascular referral base over a 10-month period. All cases required valve replacement surgery. METHODS: Clinical history, echocardiograms, and microbiologic and histopathologic data were reviewed for 7 patients with surgical CNS-NVE. RESULTS: Four patients had intravenous central catheters, and 1 had recent surgery, whereas the remaining 2 had no identifiable risk factors. Presentations ranged from subacute (4 cases) to acute with complications (3 cases). Complications included congestive heart failure, stroke, and heart block. Echocardiography demonstrated valvular lesions in all 7 cases. Valve pathologic study demonstrated gram-positive cocci in all 7 cases; blood cultures grew coagulase-negative staphylococci in 6 cases and valve cultures grew Staphylococcus epidermidis in 5 cases. CONCLUSIONS: Coagulase-negative staphylococci, including S epidermidis, can cause severe native valve endocarditis requiring valve replacement. The increasing use of intravascular access devices in the community may herald an increase in the incidence of CNS-NVE. A high index of diagnostic suspicion in the appropriate clinical setting is critical for optimal management.

Adult↗
PubMed2001

Airborne coagulase negative staphylococci produced by a sewage treatment plant.

Since some coagulase-negative staphylococci species are involved in clinical and environmental situations, the authors carried out a study on the spread of these bacteria in the air of a sewage treatment plant. For these purposes a total of 196 samples were taken from 16 sampling stations, 11 during the day and 5 at night (only at 4 points), using the settle plate technique. Altogether 13 species of coagulase negative staphylococci were isolated: S. haemolyticus, S. xylosus and S. cohnii were particularly common. Station no. 2 (an area almost always kept closed containing the fine screens) was found to be the most contaminated. The presence of coagulase negative staphylococci was favoured by high temperatures and low humidity. No differences were found due to variations in wind speed and direction or between day and night.

Air Pollutants↗
PubMed1999

Antibiotic susceptibility of staphylococci isolated in blood cultures in relation to antibiotic consumption in hospital wards.

A total of 510 isolates of Micrococcaceae, 500 of staphylococci and 10 micrococci, detected in 485 (3.3%) of 14,860 consecutive blood cultures obtained from patients at a Swedish university hospital and 2 local hospitals were identified to species level and investigated for antibiotic susceptibility. The 5 most frequently isolated species were Staphylococcus epidermidis (54.8%), S. aureus (28.0%), S. hominis (3.4%), S. warneri (3.2%) and S. haemolyticus (2.8%). All isolates of S. aureus were oxacillin sensitive. Great diversity in antibiotic resistance among coagulase negative staphylococci between hospitals and different ward units in the university hospital was observed. The frequency of antimicrobial resistance among S. epidermidis correlated with the antibiotic consumption at different ward units, in particular for ciprofloxacin (p < 0.001) and co-trimoxazole (p < 0.004). The study emphasizes the importance of monitoring antibiotic consumption and resistance patterns of nosocomial staphylococci in order to avoid emergence and spread of multi-resistant bacteria within the hospital environment.

Anti-Bacterial Agents↗
PubMed1962

Factors relating to the virulence of Staphylococci. II. Observations on four mouse-pathogenic strains.

Four clumping factor-negative strains of Staphylococcus aureus were found to closely resemble the diffuse colonial variant of the Smith strain. All produced fatal intraperitoneal infections in mice, all grew in diffuse, streaming colonies in plasma or serum soft agar, and all behaved like encapsulated microorganisms in in vitro opsonic systems. These staphylococci were resistant to phagocytosis in the peritoneal cavities of normal mice. When mice were immunized with heat-killed vaccines prepared from the Smith diffuse variant these strains were rapidly ingested by peritoneal leukocytes and the animals survived. This observation suggests that these strains share the same or a similar phagocytosis-retarding antigen. While most pathogenic staphylococci isolated from human material do not behave like these unusual mouse-virulent strains, indirect evidence is cited to support the suggestion that other staphylococci may acquire similar phagocytosis-resisting characteristics during in vivo multiplication. Studies to support or refute this thesis are in progress.

Animals↗
PubMed1992

Molecular epidemiology of coagulase-negative staphylococci isolated from immunocompromised patients.

OBJECTIVE: To define the source of invasive coagulase-negative staphylococci (CNS) and the epidemiology of strain variation in immunocompromised patients. DESIGN: Weekly microbial surveillance cultures were obtained from the nares, throat, skin, rectum, and urine. Plasmid pattern analysis was performed on all coagulase-negative staphylococci isolated from blood cultures and on selected strains from the surveillance sites. SETTING: A 902-bed, university-owned, tertiary-care referral hospital. PARTICIPANTS: Forty-four patients on the bone marrow transplant or hematologic malignancy services. RESULTS: Plasmid pattern analysis was performed on 340 surveillance isolates (median = 7 per patient) and 201 bloodstream isolates (median = 3 per patient). Patients were colonized with numerous unique strains (median = 5 per patient) of coagulase-negative staphylococci. The 44 patients had 108 episodes of positive blood cultures, 20 of which were preceded by colonization with the same strain. Isolation of the matching strain from surveillance cultures preceded the positive blood culture by 1 to 8 days in 9 episodes and 18 to 389 days in 11 episodes. The matching strain was isolated from the skin in only 6 (30%) of those episodes and from mucosal sites in 70%. Of the 108 episodes of positive blood cultures, 21 were identified as nosocomial bloodstream infections. Four of the 21 nosocomial bloodstream infections were preceded by colonization with the same strain. In all 4 episodes, the infecting strain was cultured from the nares before the blood cultures were obtained. CONCLUSIONS: Our results suggest that mucous membranes might be sources for strains of CNS causing bacteremia.

Coagulase↗
PubMed1998

Antimicrobial resistance in staphylococci and enterococci in 10 Portuguese hospitals in 1996 and 1997. POSGAR. Portuguese Study Group of Antimicrobial Resistance.

During a 2-year period, 10 Portuguese hospitals located throughout the country studied antimicrobial susceptibilities of clinically relevant staphylococci and enterococci. Of more than 12,000 Staphylococcus aureus isolates tested, two main patterns were found, methicillin-sensitive organisms most of them resistant only to penicillin but a few to other antimicrobials and methicillin-resistant S. aureus (MRSA) strains (prevalence 48.2%) resistant to most of the antimicrobials tested and uniformly susceptible to vancomycin. Among coagulase-negative staphylococci (CNS), 71% of S. epidermidis (approximately 5,000 isolates tested) and 84% S. haemolyticus (approximately 1,000 isolates tested) were also resistant to methicillin as well as most other antimicrobials except vancomycin. Most of the 5,000 Enterococcus faecalis isolates tested were susceptible to ampicillin and vancomycin, in contrast to 650 E. faecium isolates, 70% of which were resistant to ampicillin and 20% to vancomycin and all other antibiotics. A high prevalence of aminoglycoside resistance occurred in both Enterococcus species. This survey showed that resistance profiles of staphylococci and enterococci hospital isolates have not changed in the last 5 years in Portugal, with the exception of the rise in vancomycin resistance in E. faecium. The high prevalence of methicillin resistance in S. aureus and in the CNS remains an issue of medical concern.

Anti-Bacterial Agents↗
PubMed1995

Epidemiology of the colonization of inpatients and outpatients with ciprofloxacin-resistant coagulase-negative staphylococci.

We tested the skin staphylococcal flora of inpatients and hospital staff in the orthopedic unit of Turku University Central Hospital (Turku, Finland) for susceptibility to ciprofloxacin. Ciprofloxacin-resistant coagulase-negative staphylococci were detected on the skin of 14 (61%) of the 23 inpatients and 16 (53%) of the 30 members of the hospital staff. Plasmid profiles were highly similar for most of these resistant isolates, thus suggesting that cross infection was responsible for the spread of ciprofloxacin-resistant strains in the orthopedic unit. Colonization of inpatients with ciprofloxacin-resistant coagulase-negative staphylococci was significantly associated with hospitalization longer than 6 days (P = .006) and the use of antibiotics during the hospital stay (P = .009). Twelve of 30 outpatients with venous leg ulcers were treated with ciprofloxacin, and all of these 12 were colonized with ciprofloxacin-resistant coagulase-negative staphylococci; in contrast, only three (33%) of the nine outpatients who were treated with trimethoprim (P = .004) and three (33%) of the nine outpatients who were treated with placebo (P = .004) were colonized with these strains. The ciprofloxacin-resistant strains from the outpatients had distinctly different plasmid profiles, a finding that suggests that, in the community, ciprofloxacin resistance may have emerged in isolates from each treated individual.

Anti-Infective Agents↗
PubMedDate not supplied

Influence of subinhibitory concentrations of antibiotics on virulence of staphylococci.

The understanding and control of infections caused by staphylococci are still far from complete, and staphylococcal infections continue to be a serious problem. The organisms possess numerous virulence factors that can act independently to induce various symptoms and lesions. Chemotherapy has changed the clinical spectrum of staphylococci but has not eradicated serious staphylococcal infections. An evaluation of the interaction of antibiotics, staphylococci, and host defense will help to identify those factors that determine the success or failure of therapy for staphylococcal infections. The activity of antibiotics is usually expressed in terms of concentrations that either inhibit or kill microorganisms in vitro or in experimental infections. Subinhibitory concentrations of antibiotics may induce changes in bacterial properties both in vitro and in vivo. An understanding of the mechanism of such changes would allow a more rational application of antibiotics that have both specific antistaphylococcal action and positive effects on host defense mechanisms.

Anti-Bacterial Agents↗
PubMed1986

Usefulness of a test for slime production as a marker for clinically significant infections with coagulase-negative staphylococci.

The usefulness of a test for slime production as a marker for clinically significant infections with coagulase-negative staphylococci and its implications for therapy were examined. Hospital records were reviewed for 59 patients from each of whom more than one isolate of coagulase-negative staphylococci was obtained. In patients with a prosthetic device, 81% of 59 infectious episodes were due to a slime-positive coagulase-negative staphylococci. In contrast, 22 noninfectious episodes (in which the organisms were contaminants) were equally distributed between episodes due to slime-positive or slime-negative isolates (P = .005). Only 32% of infections caused by slime-positive organisms, in contrast to 100% of infections caused by slime-negative organisms, were improved by treatment with antibiotics alone (P = .02). Prosthetic device removal in addition to antibiotic treatment significantly improved the outcome in patients with infections due to slime-positive organisms when compared with treatment with antibiotics alone (93% vs. 32% improvement; P = .00025).

Anti-Bacterial Agents↗
PubMed1988

Characteristics of adherence to plastic tissue culture plates of coagulase-negative staphylococci exposed to subinhibitory concentrations of antimicrobial agents.

Adherence and hydrophobic properties characteristic of 6-h cultures of coagulase-negative staphylococci on plastic tissue culture plates were determined after the organisms had been treated for up to an additional 6 h with subinhibitory concentrations of antimicrobial agents. Clindamycin, erythromycin, norfloxacin, tunicamycin, and vancomycin had no effect. Cephalothin, chloramphenicol, gentamicin, imipenem, methicillin, novobiocin, polymyxin B, rifampin, and tobramycin had varied effects. Most changes induced by these agents resulted in differing degrees of inhibition of adherence. However, an increase in adherence of 65% was observed for one strain, RP14 (ATCC 35981), with rifampin treatment. Hydrophobicity of coagulase-negative staphylococci treated with antimicrobial agents measured by using a biphasic system with hexadecane showed excellent correlation with adherence (r = .958, P less than .0005), a result suggesting that adherence of these bacteria in this system depends heavily on hydrophobic surface moieties. Transmission electron microscopy of drug-treated coagulase-negative staphylococci revealed only an increase in cell-wall thickness, regardless of whether adherence was increased or decreased.

Anti-Bacterial Agents↗
PubMed1988

The development of antimicrobial resistance in staphylococci.

Staphylococci are among the most important aetiological agents of both community- and hospital-acquired infections. Staphylococcus aureus isolates resistant to penicillin because they produced beta-lactamase were isolated soon after the introduction of penicillin as a therapeutic agent. The production of beta-lactamase was mediated by a plasmid. The incidence of penicillin resistance in S. aureus increased during the succeeding decades until most clinical isolates were resistant to penicillin. During the 1940s and 1950s resistance to other antimicrobial agents was also demonstrated, usually in combination with penicillin resistance, thus creating multi-resistant strains. Methicillin, a penicillin that was essentially resistant to staphylococcal beta-lactamase, was introduced into clinical use in the early 1960s and this alleviated much of the problem of antimicrobial resistance in S. aureus, but methicillin-resistant strains were soon isolated. Although methicillin-resistant staphylococci had been a nosocomial problem in Europe in the 1960s and early-1970s, it was not until the mid-1970s that they became a problem in the United States. Since then the incidence of methicillin-resistant S. aureus has steadily increased. The methicillin-resistant S. aureus strains are usually multi-resistant including the beta-lactams and one or more of the following: aminoglycosides, macrolides, lincosamides, tetracyclines (usually not minocycline), and chloramphenicol. The methicillin-resistant S. aureus are generally susceptible to vancomycin, teicoplanin, rifampicin, coumermycin, minocycline, the quinolones, and sulphamethoxazole-trimethoprim. The coagulase-negative staphylococci are also important aetiological agents of nosocomial infections and the incidence of these infections has increased in recent years.(ABSTRACT TRUNCATED AT 250 WORDS)

Coagulase↗
PubMed1990

Skin carriage of antibiotic-resistant coagulase-negative staphylococci in untreated subjects.

A detailed microbiological analysis was made of the antibiotic resistant coagulase-negative staphylococcal flora of facial skin of 64 untreated individuals. The flora was quantified at primary isolation using both non-selective and selective media (each containing one of seven different antibiotics). The isolates obtained were tested against 18 antibiotics for multiple resistance and biotyped to species level. The incidence of the seven primary antibiotic resistance markers among the staphylococcal flora of 64 untreated subjects was: tetracycline 87.5%, erythromycin 68.8%, fusidic acid 56.3%, trimethoprim 42.4%, chloramphenicol 25%, clindamycin 9.4% and gentamicin 4.7%. In addition, penicillin resistant staphylococci were isolated from 98% of subjects. Multiply resistant strains were carried by 62.5% of individuals, with 27.9% carrying more than 100 multiply resistant staphylococci/cm2 skin. Analysis of the frequency distributions of the size of resistant staphylococcal populations revealed considerable individual variation, with many individuals carrying greater than 10(3) resistant staphylococci/cm2 skin. Multiply resistant staphylococci usually comprised less than 10% of the total staphylococcal flora, although this often represented a large number of multiply resistant organisms. Three people carried greater than 10(4) multiply resistant staphylococci/cm2 skin. Most of the singly and multiply resistant isolates were identified as strains of Staphylococcus epidermidis, which was found to carry up to eight resistances per isolate. In contrast, S. capitis, a common resident of human facial skin, was never found to carry more than two resistances per isolate. S. aureus was rarely detected on intact facial skin and the strains were not multiply resistant. Resistance to the major antistaphylococcal antibiotics was infrequent (gentamicin, methicillin) or absent (rifampicin, vancomycin, cephalothin). It was concluded that untreated individuals carry a significant pool of singly and multiply resistant staphylococci of sufficient size to be readily disseminated by direct contact and desquamation.

Adolescent↗