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Further observations on the behavior of staphylococci within human leukocytes.

A specific serum factor was required for rapid phagocytosis of pathogenic staphylococci by human polymorphonuclear leukocytes when the ingestion process was studied in siliconed glass systems and the concentrations of staphylococci were maintained at low levels. In contrast to certain other microbes, the resistance to phagocytosis which characterized pathogenic staphylococci was relative, and phagocytosis was readily accomplished when large populations of staphylococci were present in the test system. A factor promoting phagocytosis was present in eight of eight normal adult sera. In contrast, the sera of twenty-eight of thirty normal rabbits did not promote phagocytosis. Serum obtained from 2 rabbits maintained in the rabbit colony for several months acquired the ability to opsonize pathogenic staphylococci. The phagocytosis-promoting factor was almost completely removed by prior absorption of test sera with the homologous strain. The factor was incompletely removed by absorption with heterologous strains of pathogenic staphylococci and was not significantly reduced by absorption with coagulase-negative staphylococci or unrelated microorganisms. Present evidence suggests that the factor promoting phagocytosis is a thermostable opsonin. While the activity of heated serum could not be restored by the addition of small amounts of fresh serum or complement, the addition of large amounts of complement partially restored opsonic activity. Incubation of staphylococci in fresh serum prior to heat inactivation did not reduce subsequent phagocytosis, further suggesting the heat stability of the phagocytosis-promoting factor. Preliminary studies correlating the presence of antistaphylococcal hemagglutinins and phagocytosis-promoting factor in certain sera suggest that the two factors were not necessarily related. The phagocytosis of staphylococci in fresh human serum was inhibited by the addition of fresh or inactivated rabbit serum. Further studies on the nature of such inhibition are in progress. Once ingestion was accomplished, coagulase-positive staphylococci consistently survived in significant numbers within the cytoplasm of human granulocytes. Coagulase-negative staphylococci appeared to be destroyed within the leukocyte and could not be recultured from the cytoplasm following 3 to 4 hours of intracellular residence.

Adult↗

Staphylococci, in vitro and in vivo.

Strains of Staphylococcus aureus were grown in broth and by the membrane technique; both drug-free media and media containing cloxacillin were used. The staphylococci grown in broth containing cloxacillin showed one thick cross wall and were larger than those grown in drug-free broth: 1.6 micron in diameter as opposed to 0.9 micron. The staphylococci grown on membranes placed on agar containing cloxacillin were 2-3 microns in diameter and contained three or more cross walls. Mice were infected intraperitoneally with staphylococci. After treatment with cloxacillin, the peritoneal fluid and spleens contained staphylococci that were 2-3 microns in diameter with three or more cross walls. A staphylococcal endocarditis was induced in rabbits that were then treated with cloxacillin. The staphylococci in the vegetation of the treated rabbits were 2-3 microns in diameter and contained multiple cross walls. Large staphylococci with multiple cross walls were observed in specimens from patients with respiratory infections treated with beta-lactam antibiotics. It appears, therefore, that the ultrastructure of staphylococci in vivo is comparable to that of staphylococci grown on a solid support medium such as a membrane, and different from that of staphylococci grown in a liquid medium.

Animals↗

The behavior of virulent and avirulent staphylococci in the tissues of normal mice.

The fate of hemolytic staphylococci injected intravenousiy into albino mice was followed by determining quantitatively the numbers of living organisms present in the various tissues at different intervals of time after infection. Irrespective of the strain of staphylococcus used, most of the organisms disappeared rapidly from the blood, liver, spleen, and kidneys. This was true even when the infective dose consisted of large numbers of virulent, coagulase-positive staphylococci, capable of producing a fatal disease in a high percentage of the infected mice. The initial rate of removal or destruction of staphylococci was particularly high in the lungs and kidneys. In all cases on the other hand, a few living staphylococci persisted in the various organs for several weeks after infection, even when the organisms were non-virulent and coagulase-negative. Although virulent as well as avirulent staphylococci were eliminated extremely rapidly and efficiently from the kidneys during the initial stage of infection, the microorganisms soon began to multiply in this organ, causing abscesses first detected in the cortex. Death of the animals infected with virulent cultures appeared to be due to the destruction of renal tissue by these abscesses. The abscesses caused by the avirulent strains eventually became sterile, and healed. No convincing difference could be recognized amongst seven strains in their resistance to the bactericidal power of the mouse tissues during the initial phase of the infection. In contrast, marked quantitative differences came to light in their subsequent behavior in the kidneys. The multiplication of the coagulase-negative staphylococci in this organ soon came to an end in all animals and never proceeded far enough to result in fatal disease. The staphylococci of a weakly coagulase-positive strain multiplied somewhat more extensively in the kidneys than did the coagulase-negative, but never sufficiently to cause the death of any animal within the period of observation of 1 month. The three coagulase-positive strains tested yielded the largest bacterial population in the kidneys and caused the death of many of the infected animals. These three virulent strains differed quantitatively amongst themselves with regard to both the rapidity and extent of their multiplication in the kidneys and the lethal power of a given infective dose. Taken together, the findings indicate that the hemolytic strains of staphylococci can be arranged in a continuous spectrum according to their ability to cause disease in albino mice. Although virulence for these animals appeared to be correlated with the production of coagulase, it did not seem to depend upon the ability of this substance to interfere with the bactericidal mechanisms of the mouse organs during the early phase of the infection. Virulence manifested itself chiefly by the production in the kidneys of progressive abscesses originating from the few staphylococci which were not destroyed during the initial bactericidal reaction.

Animals↗

Staphylococci express a receptor for human transferrin: identification of a 42-kilodalton cell wall transferrin-binding protein.

Staphylococcus aureus and the coagulase-negative staphylococci are commonly responsible for peritonitis in renal patients undergoing continuous ambulatory peritoneal dialysis. To simulate growth conditions in vivo, staphylococci isolated from peritoneal infections were cultured in used human peritoneal dialysate (HPD). Immunoblotting experiments using cell wall preparations from these staphylococci revealed the presence of the host iron-binding glycoprotein transferrin bound to S. aureus, S. epidermidis, S. capitis, S. haemolyticus, and S. hominis but not to S. warneri or S. saprophyticus. Similar results were obtained by incubating broth-grown staphylococci with human transferrin, although, in contrast to S. aureus, the coagulase-negative staphylococci bound more transferrin after growth in iron-restricted broth. To determine whether the staphylococci express a saturable specific receptor for human transferrin, the interaction of human 125I-transferrin with the staphylococci was examined. Both S. aureus and S. epidermidis bound the radiolabelled iron-saturated ligand in a time- and concentration-dependent manner. From competition binding assays, the affinity (Kd) and number of receptors were estimated for S. epidermidis (Kd, 0.27 microM; 4,200 receptors per cell) and S. aureus (Kd, 0.28 microM; 4,200 receptors per cell). S. epidermidis but not S. aureus receptor activity was partially iron regulated. Human apotransferrin and iron-saturated transferrin and rabbit and rat transferrins competed equally well for the staphylococcal receptor. Bovine and porcine transferrins and ovotransferrin as well as human and bovine lactoferrins were much less effective at competing with human transferrin. Treatment of whole staphylococci with protease abolished transferrin binding, indicating the involvement of cell surface protein. Western blots (immunoblots) of cell wall preparations probed with human transferrin revealed the presence of a 42-kDa transferrin-binding protein common to both S. aureus and S. epidermidis. On Western strip blots, the binding of human transferrin to this protein was blocked by labelled human transferrin but not by albumin, immunoglobulin G, or bovine transferrin or ovotransferrin. To assess the conservation of the 42-kDa transferrin-binding protein, cell wall proteins of S. epidermidis, S. haemolyticus, S. capitis, S. hominis, S. warneri, and S. saprophyticus were Western blotted and probed with human transferrin. Only S. warneri and S. saprophyticus lacked the 42-kDa wall protein, consistent with their inability to bind transferrin. These data show that the staphylococci express a specific receptor for human transferrin based at least in part on a common 42-kDa cell wall protein.

Animals↗

Staphylococci-induced human platelet injury mediated by protein A and immunoglobulin G Fc fragment receptor.

Bloodstream infections with staphylococci are accompanied by thromboembolic complications. We have studied the mechanism of the interaction of staphylococci with human blood platelets. Staphylococci that possess protein A, a bacterial receptor for the Fc fragment of immunoglobulin G (IgG), caused aggregation of human platelets in whole plasma accompanied by release of [(3)H]serotonin. These reactions were time and concentration dependent, requiring two or more staphylococci per platelet to give maximal response within 5 min. The interaction between staphylococci and platelets required the presence of cell wall-bound protein A and of IgG with an intact Fc fragment. It did not require an intact complement system. Cell wall-bound protein A (solid phase) was capable of aggregating human platelets in whole plasma. In contrast, free, solubilized protein A (fluid phase) did not cause measurable aggregation, and release of [(3)H]serotonin was reduced. An excess of free, solubilized protein A blocked aggregation of human platelets induced by staphylococci in whole plasma. The role of the Fc fragment of IgG in the staphylococci-human platelet interaction was demonstrated by an experiment in which free, isolated Fc fragment blocked aggregation of platelets in whole plasma induced by staphylococci. Furthermore, binding of (125)I-protein A to human platelets was demonstrated in the presence of complete IgG with intact Fc fragment but not in the presence of the F(ab)(2) fragment. Binding of the protein A-IgG complex to the human platelet Fc receptor was paralleled by the release of [(3)H]serotonin. These results represent a novel example of the interaction of two phylogenetically different Fc receptors, one on prokaryotic staphylococci and the other on human platelets. Their common ligand, IgG, is amplified by one Fc receptor (protein A) to react with another Fc receptor present on human platelets, which results in membrane-mediated aggregation and release reaction occurring in whole plasma. This mechanism can be of significance in the pathomechanism of thromboembolic complications at the site(s) of intravascular staphylococcal infection.

Binding Sites↗

Importance of food handlers as a source of enterotoxigenic staphylococci.

The incidence of staphylococci in the nasal fossae of 300 food handlers working within the province of León (Spain) was studied. Sampling was carried out using a swabbing technique. For the quantitative estimation of staphylococci, a direct plating method and an enrichment procedure (MPN) were used simultaneously. Gram positive cocci that fermented glucose and were sensitive to lysostaphin (1 unit/ml) were found to be present in the noses of 201 food handlers (67%). Eighty three of them (27.6%) were carriers of coagulase positive staphylococci and 118 (39.3%) of coagulase negative staphylococci. The carriage rate of coagulase negative staphylococci was slightly higher in winter but carriers of coagulase positive strains were more frequently found during warmer months. Coagulase positive staphylococci appeared to be more often carried by males. In all instances, positive nasal cultures gave 10 or more colonies per sample. The majority of food handlers carrying coagulase negative staphylococci (64.4%) yielded counts between 10(3)-10(5) CFU per swab. Thirty four (40.9%) of the nasal carriers of coagulase positive staphylococci yielded more than 10(4) CFU per sample. The higher counts corresponded to this latter group. Preliminary enrichment did not increase the number of nasal carriers detected. Although a good correlation was observed between the results of direct plating and the MPN procedure (r = 0.87 +/- 0.04), the MPN technique gave lower counts. Thirty six (12%) individuals carried enterotoxigenic staphylococci. The incidence among carriers of coagulase positive strains was 43.4%. The enterotoxin types produced were: A (12 strains), B (8 strains), C (7 strains), D (2 strains), E (2 strains), A + D (4 strains) and B + C (1 strain). Most of the food handlers who harbored enterotoxigenic strains gave high nasal counts.

Carrier State↗

Dissemination of staphylococci in mice with experimental mastitis.

During the course of an acute, fatal mastitis in mice caused by intra-mammary injection of approximately 10(5) cfu of Staphylococcus aureus, small numbers of staphylococci were detected in liver, spleen, kidney and heart. Transport from the mammary gland was by the venous blood system with no evidence of lymph node involvement. Intravenous injection of 100 times more staphylococci (approximately 10(7) cfu) than were fatal by the intramammary route failed to kill the mice and small numbers of staphylococci were found in the visceral organs. However, intravenous injection of approximately 10(8) cfu of Staph. aureus was fatal and large numbers of staphylococci were found in the visceral organs. Treatment with cloxacillin (500 micrograms) by the intramammary or subcutaneous routes, or equally divided between these two routes, cleared the visceral organs of staphylococci; subcutaneous therapy had a limited and variable effect on numbers of staphylococci in the mammary gland while intramammary and divided treatments significantly reduced the numbers of staphylococci. Thus, staphylococci are disseminated to visceral organs during acute staphylococcal mastitis, but this makes a negligible contribution to the clinical disease.

Animals↗

Low-level colonization of hospitalized patients with methicillin-resistant coagulase-negative staphylococci and emergence of the organisms during surgical antimicrobial prophylaxis.

By use of techniques that have been developed to detect small numbers of methicillin-resistant staphylococci, we cultured samples from the nares and subclavian and inguinal areas of 29 patients before and after cardiac surgery and 10 patients before and after coronary angioplasty. Methicillin-resistant coagulase-negative staphylococci were recovered before the surgical or angioplasty procedure from 74% of patients. The quantitative recovery of methicillin-resistant isolates before cardiac surgery or coronary angioplasty was compared with the number of methicillin-resistant staphylococci detected at the same site 3 days after the procedure. In cardiac surgery patients (who received antibiotic prophylaxis), 17 of the 28 sites (61%) in which low-level colonization with methicillin-resistant strains was detected preoperatively contained high levels of methicillin-resistant staphylococci postoperatively. In contrast, coronary angioplasty patients (who did not receive antibiotic prophylaxis) did not have any of the 14 sites containing low levels of methicillin-resistant strains before angioplasty emerge to harbor high levels of methicillin-resistant staphylococci after angioplasty. Methicillin-resistant coagulase-negative staphylococci from each site in which high levels of methicillin-resistant staphylococci emerged postoperatively were paired with preoperative isolates from the same site. Identical antibiograms and plasmid profile patterns were demonstrated for seven of the pre- and postoperative isolate pairs, suggesting that the high levels of methicillin-resistant coagulase-negative staphylococci detected on the skin or in the nares after cardiac surgery were derived from methicillin-resistant organisms present at the site preoperatively in much smaller numbers.

Angioplasty, Balloon↗

[Influence of antagonistic flora on quantity of staphylococci in the oral cavity].

The study was aimed at establishment, whether in oral cavity co-inhabit bacteria demonstrating antagonistic properties against staphylococci and whether this phenomenon may influence the size of staphylococcal population in this environment. Two locations of bacteria in oral cavity were investigated--saliva and tooth plaque. It was found that total quantity of staphylococci (both coagulase-positive and/or coagulase-negative) in saliva decreases with the age of investigated persons. Mean values amount respectively for children to 3.5 +/- 1.0 log CFU/ml and for adults to 2.9 +/- 0.7 log CFU/ml. This is statistically different (p = 0.0003). Amount of staphylococci in tooth plaques remains generally at the same level and amount to 1.4 +/- 0.6 log CFU/ml. In each tested sample of saliva and tooth plaque, presence of bacteria antagonistic to isolated from a given sample staphylococci, was detected. Among 2-4 year children and in adults, percentages of antagonistic bacteria against coagulase-positive staphylococci were higher than against coagulase-negative strains. Among children aged 5-6 and 11-13 years opposite proportions were found. Statistic analysis confirmed existence of negative correlations, both linear and ranking, between quantity of antagonistic bacteria and amounts of coagulase-positive and coagulase-negative staphylococci in the same tested samples of saliva and tooth plaque. These results suggest that antagonism between bacterial flora of oral cavity and staphylococci, is presenting one of factors limiting the quantity of staphylococci in this environment.

Adolescent↗

STAPHYLOCOCCI IN COMPETITION. V. EFFECT OF EGGS, EGGS PLUS CARBOHYDRATES, AND LIPIDS ON STAPHYLOCOCCAL GROWTH.

As is generally known, custards have been frequently involved in staphylococcal food poisonings and are regarded by some as an ideal culture medium. Previous studies showed that high carbohydrate concentrations repressed the growth of competing saprophytic species, allowing the growth of staphylococci in a mixture rather than stimulating the growth of the staphylococci. In an extension of those studies, the influence of the egg constituent of custard was investigated to determine its role in affecting the growth of pathogenic staphylococci in a competing mixture of psychrotrophic saprophytes. The normal competitive effect of the saprophytes on the growth of staphylococci was very slightly affected by the addition of 25% whole egg to the growth media. Approximately 9% egg yolk alone added to the medium resulted in a slight increase in the length of the lag period of the psychrotrophs and a slight increase in the number of staphylococci which grew. Addition of 25% whole egg plus 14.5% sucrose resulted in repression of saprophyte growth similar to that seen in high sucrose concentrations. Staphylococcal growth was more extensive in the presence of both whole egg and sucrose than in the presence of either ingredient alone. Incorporation of 4% corn oil in media was effective in repressing growth of the saprophytes at 37 C only. This allowed the staphylococci to dominate the population. At lower temperatures, staphylococci were unable to compete effectively. Buffering media of high carbohydrate content resulted in lengthened lag periods for the psychrotrophs and the appearance of very large staphylococcal populations.

Carbohydrates↗

COMPARATIVE EVALUATION OF FIVE SELECTIVE AND DIFFERENTIAL MEDIA FOR THE DETECTION AND ENUMERATION OF COAGULASE-POSITIVE STAPHYLOCOCCI IN FOODS.

Five selective media for the detection and enumeration of coagulase-positive staphylococci were evaluated for their efficiency in the recovery of 17 strains of coagulase-positive staphylococci from foods. They were Staphylococcus Medium 110 (SM-110), tellurite-glycine-agar (TGA), egg-tellurite-glycine-pyruvate-agar (ETGPA), tellurite-egg-agar (TEA), and tellurite-polymyxin-egg yolk-agar (TPEY). Statistical analysis by the rank correlation method of the efficiency with which these media recovered staphylococci from pure 24-hr Brain Heart Infusion cultures revealed the following efficiencies in descending order: (i) TPEY, (ii) ETGPA, (iii) TGA, (iv) TEA, (v) SM-110. Growth of 17 strains of coagulase-negative cocci on these media showed the following approximate descending order of inhibition to these organisms: (i) ETGPA, (ii) TEA, (iii) SM-110, (iv) TGA, (v) TPEY. The appearance of colonies of the various coagulase-negative strains on each medium was studied for the degree to which they could be confused with colonies of coagulase-positive strains. Nineteen food contaminants, including Proteus vulgaris, Bacillus sp., Escherichia coli, Erwinia sp., fecal streptococci, and others, were also studied for similarities in appearance to staphylococci and for ability to grow on the selective media. The influence of five sterile food homogenates (frozen chicken and tuna pies, custard, smoked ham, and raw whole egg) on recovery of 1,500 enterotoxigenic staphylococci (three strains) per milliliter was determined by statistical analysis. Three main effects (culture, media, and food) and three interactions (media with food, food with cultures, and media with culture) were found to be significant. Recovery on TPEY was influenced less by food than the other selective media and showed optimal recovery ability from sterile custard, eggs, and ham. TGA recovered well from sterile chicken pie and custard, SM-110 from sterile custard, and TEA from sterile ham. None of the media was outstanding in recovering staphylococci from tuna pie. The ability of the five selective media to recover 1,500 enterotoxigenic staphylococci (three strains) per ml from three sterile foods in the presence of 10 strains of contaminating bacteria added at the 0, 10(5), and 10(6) levels per milliliter was also studied and analyzed statistically. Only three factors were significant under these conditions-cultures, foods, and the interaction of media with the level of added contamination. Efficiency of recovery of TGA, SM-110, and ETGPA was found not to be dependent upon the level of contamination. Recovery on TPEY decreased with increases in the number of contaminants. TEA increased in efficiency at the 10(5) level, but decreased at the 10(6) level. When recovery on Trypticase Soy Agar was considered to be 100%, the average percentage of recovery by each of the selective media under all experimental conditions was determined.

Agar↗

Reservoirs of coagulase negative staphylococci in preterm infants.

This investigation was undertaken to determine the magnitude of, and interrelations between, reservoirs of coagulase negative staphylococci on infants' skin at various sites (including sites used for insertion of intravascular catheters) and in faeces during the first six months of life. Sites with large numbers of coagulase negative staphylococci were identified by sampling 16 skin sites and stools from 20 preterm neonates at 8-30 days of life. A more detailed survey of numbers and types of coagulase negative staphylococci in stool and at six skin sites of 10 preterm infants was then performed over the first six months of life. Isolates of coagulase negative staphylococci were collected and characterised by speciation, antibiotic susceptibility profiling, and plasmid restriction fragment length polymorphism analysis. Large, relatively stable reservoirs were identified in the faeces, around the ear, and in the axilla and nares. Skin on the forearm and leg, sites at which peripheral catheters are frequently sited, carried small unstable numbers of coagulase negative staphylococci, which were usually indistinguishable from coagulase negative staphylococci isolated from other body sites on the same baby. Contamination of catheter insertion sites with coagulase negative staphylococci from reservoir sites on the same baby could explain these observations. These data suggest that interventions reducing cross-contamination between sites on the same baby might be as important in preventing coagulase negative staphylococcal bacteraemias as measures taken to prevent cross infection between babies. Procedures which are likely to result in heavy coagulase negative staphylococcal contamination of the hands of healthcare staff, such as changing soiled nappies, should receive particular attention.

Bacteremia↗

Prevalence of coagulase-negative staphylococci in bovine mastitis in Zimbabwe.

This study was carried out to determine the prevalence of coagulase-negative staphylococci in clinical and subclinical mastitis in commercial and small-scale farms in Zimbabwe. Thirty five quarter milk samples from clinical mastitis cases and 371 quarter milk samples from cows with subclinical mastitis were cultured for bacterial pathogens. The most frequent pathogens isolated in clinical mastitis were the enteric bacteria (31.4%), followed by coagulase negative staphylococci (22.9%) and then Staphylococcus aureus (17.1%), whereas in subclinical mastitis S. aureus (34.2%) and coagulase-negative staphylococci were (33.2%) the most common. Bacillus species were only isolated in milk samples from subclinical mastitis. Coagulase-negative staphylococci were observed in mixed infections with other bacteria in only 2.2 of the 406 milk samples from clinical and subclinical mastitis where they were isolated together with Bacillus species in 6 of the 9 mixed infection cases. About 95% of the milk samples from which 131 coagulase-negative staphylococci were isolated had correspondingly high somatic cell counts. The coagulase-negative staphylococci isolated most frequently were S. chromogenes (7.9%), S. epidermidis (7.4%) and S. hominis (5.9%). They were all associated with high somatic cell counts. All the coagulase-negative staphylococci isolates were susceptible to cloxacillin and erythromycin, and more than 90% of the isolates were susceptible to neomycin, penicillin and streptomycin. The highest resistance was to tetracycline (17.6%), followed by lincomycin (13.7%). About 8% of the isolates were resistant to both penicillin and streptomycin.

Animals↗

Potential use of presumptive enterococci and staphylococci as indicators of sanitary condition in plants making hard Italian-type cheese.

Raw milk, pasteurized milk, unripened cheese (1 day old), and partially ripened cheese (3 months) from 42 milk lots at a plant making hard Italian-type cheese were analyzed for presumptive enterococci using kanamycin esculin azide agar pour plates. Fully ripened (> or =10 months) cheeses, derived from other milk lots, were also tested. Numbers of presumptive staphylococci (Baird-Parker agar [B-P]) were determined in the partially and fully ripened cheeses. Presumptive enterococci were ubiquitous in raw milk, usually at levels of 2.1 to 3.0 log CFU/ml. Enterococci were detected in 11 (26%) of 42 pasteurized milk samples. Enterococci and staphylococci were detected in 39 (93%) and 6 (14%) of unripened cheeses and in 33 (80%) and 4 (10%) of partially ripened cheeses, respectively. Only eight and five samples of enterococci-positive unripened and partially ripened cheese, respectively, were made from pasteurized milk in which presumptive enterococci were detected. Of 42 samples of fully ripened cheese, 35 (83%) and 8 (19%), respectively, contained presumptive enterococci and staphylococci. Results suggest either that low numbers of presumptive enterococci survive pasteurization and cheese ripening or that contamination of cheese by enterococci occurs after pasteurization. Biochemical testing confirmed 63% of presumptive enterococci isolates. None of the 20 presumptive staphylococci isolates produced colonies typical of Staphylococcus aureus on B-P agar; the isolates were identified as 1 Staphylococcus epidermidis, 1 Staphylococcus xylosus, 2 Staphylococcus saprophyticus, 1 Staphylococcus warneri, 5 Kocuria spp., and 10 unidentified gram-positive, catalase-positive cocci. Three staphylococci isolates decreased in numbers by more than 3.0 log CFU/ml in 9.9 ml of skim milk heated 30 min in a 62.8 degrees C water bath. This finding suggests that most presumptive staphylococci detected may have been prepasteurization contaminants. Unless specificity of the kanamycin esculin azide and B-P media is improved, use of presumptive enterococci and staphylococci as indicators of postpasteurization sanitation in plants making hard Italian-type cheese cannot be recommended.

Animals↗

Comparative antimicrobial spectrum and activity of BMS284756 (T-3811; a desfluoroquinolone) tested against an international collection of staphylococci and enterococci, including in vitro test development and intermethod comparisons.

The study was initiated to determine the in vitro activity and MIC/disk test comparisons of BMS284756, a new des-fluoro(6)-quinolone, against isolates of staphylococci and enterococci from the SENTRY Antimicrobial Surveillance Program, 2000. Isolates were tested by reference broth microdilution and standardized disk diffusion methods. Against 3,789 strains of gram-positive cocci from the SENTRY Program (2000), the BMS284756 MIC90 and percentage susceptible at < or = 2 and < or = 4 microg/ml were: Staphylococcus aureus (4 microg/ml; 89.3 and 97.1%), coagulase-negative staphylococci (CoNS; 4 microg/ml; 86.1 and 96.0%) and enterococci (> 4 microg/ml; 62.0 and 76.2%). Also tested were selected staphylococci (300 strains) and enterococci (102 strains) by two standardized methods. The activity of BMS284756 was highly correlated with oxacillin resistance among staphylococci. Oxacillin-susceptible staphylococci were all inhibited by BMS284756 at < or = 0.5 microg/ml, whereas oxacillin-resistant strains required inhibitory concentrations of > or = 1 microg/ml. Excellent correlation was observed between the MIC and 5-microg disk zone diameter for staphylococci and enterococci (r=0.91 to 0.93). Among vancomycin-susceptible enterococci, 67% of Enterococcus faecalis, 25% of E. faecium, and 76% of other Enterococcus spp. isolates were inhibited by BMS284756 at < or = 2 microg/ml. All vancomycin-resistant enterococci (VRE; 11 E. faecalis and 15 E. faecium) were inhibited by > or = 2 microg/ml of BMS284756. Among the non-VRE, non-faecium enterococcal isolates (n=64), 62% were inhibited by < or = 0.5 microg/ml. BMS284756 showed excellent activity against oxacillin-susceptible staphylococci and moderate activity against enterococci other than VRE and E. faecium. Acceptable correlations were observed between MIC and disk test results for both tested genus groups.

Anti-Infective Agents↗

[Susceptibility of the bacteria isolated from samples of clinical material in Poland in 1998 to selected chemotherapeutics and antibiotics--the analysis of the questionnaire findings. I. Susceptibility of staphylococci].

The work has been undertaken in order to attain detailed information on the antibiotic sensitivity of the identified microorganisms from different clinical material derived from inpatients, outpatients and healthy people, on various regions of Poland in 1998. Approprite questionnaires (cards) were sent to each sanitary-epidemiological stations throughout Poland. Received 28619 cards, from 44 Public Health Service laboratories, allowed to create a computerized data base in Department of Bacteriology in National Institute of Hygiene in Warsaw. Staphylococci were the most frequent etiologic pathogen isolated from the clinical material--24,7%. Among them, there were: S. aureus--75,8%, S. epidermidis--9,7%, unidentified coagulase negative staphylococci (CNS)--9,2% and S. saprophyticus--5,1%. 71,6% of staphylococci strains derived from non-hospital material and 26,7% from hospital material. Staphylococci strains isolated from inpatients specimens were more resistant to antibiotics than those from outpatients specimens. The highest resistance, among both hospital and non-hospital strains, was exhibited to penicillin (70-100%) and tetracycline (approximately 50%); the lowest to: glycopeptides, ciprofloxacin, trimethoprim/sulfametoxazole, nitrofurantoin and gentamicin. Staphylococci isolated from various clinical specimens differed in their antibiotic resistance. The percentages of coagulase-negative staphylococci strains resistant to the antibiotics used were higher than of S. aureus strains. On the average 34% of S. aureus strains were methicillin-resistant (MRSA); but depending on specimens were isolated from, it ranged from 24% of MRSA strains for ear and nose swabs to 70% of MRSA strains for feaces samples. Among MRSA strains the percentage of resistance to other antibiotics was a few time higher than among MSSA strains. The territorial distribution of staphylococci strains resistance to various antibiotics in Poland is not uniform.

Anti-Bacterial Agents↗

[Coagulase-negative staphylococci in normal and chronically inflamed conjunctiva].

UNLABELLED: This study examines the prevalence of coagulase-negative Staphylococcus species in normal and mildly inflamed conjunctiva, their sensitivity to antibiotics, and their relationship to the remaining flora. PATIENTS AND METHODS: In 99 patients including 9 HIV-positives in an early stage of the infection, 100 conjunctival swabs were taken and microbiologically investigated for bacteria and fungi. Thirty-four were from healthy eyes. 40 were from patients with chronic (n = 28) and unspecific (n = 12) conjunctivitis, 17 were from patients with a variety of outer inflammatory ocular conditions, and 9 were from the HIV group from uninfected (n = 6) and infected (n = 3) conjunctivae. Samples from each patient were collected with three moistened cotton swabs and directly inoculated onto five different agars, followed by immersion into three specific culture broths. Staphylococci were identified species-wise, the other microorganisms genus-wise. Sensitivity to a broad spectrum of antibiotics was determined by agar diffusion tests. OUTCOME: Staphylococci were found in 89%, which was the highest prevalence genus-wise. Of those, coagulase-negative species accounted for 86%, while coagulase-positive Staphylococcus aureus was isolated in 12% of all swabs. In the 86 smears positive for coagulase-negative staphylococci, 151 different strains were isolated. In these strains, resistance to the 13 tested antibiotics varied from 0% for vancomycin to 66% for penicillin. Strains which were isolated from patients with chronic conjunctivitis showed a greater range of resistance than those from normal flora, with significant levels for ciprofloxacin, gentamycin and kanamycin (Mann-Whitney) U-test: P < 0.05). All except six strains of staphylococci were identified strains represented ten species, of which Staphylococcus epidermidis was most prevalent (74%), but only made up 70% of all isolated strains of the coagulase-negative staphylococci. Staphylococcus aureus and gram-negative bacteria were found significantly more commonly in patients which chronic conjunctivitis than in healthy eyes, while coagulase-negative species of the Micrococcaceae family were significantly more prevalent in the healthy than in the chronically inflamed conjunctiva (chi-square: P < 0.05). CONCLUSION: The conjunctiva can simultaneously host several stems of coagulase-negative staphylococci, which differ in regard to species and resistance to antibiotics. This variety might indicate a microbiological balance of the conjunctiva and be reduced in chronic inflammatory conditions. In patients with chronic conjunctivitis the risk for multiresistant coagulase-negative staphylococci is increased.

AIDS-Related Opportunistic Infections↗

Staphylococci of the normal human skin flora. Variety of biotypes and antibiograms without direct correlations.

352 strains of Staphylococci of the normal human skin flora were sampled from one volunteer by single scrabbing in a ca. 3 cm2 measuring area. They were biotyped by the scheme of Pelzer et al.(1973)--a modified Baird-Parker-Scheme (1963)--and the resistance to antibiotics was investigated by the method of Bauer et al. (1966). All the nine biotypes of Staphylococci were found in variable quantities. It seems problematic to call one biotype as the main type. Morphologically identical colonies of Staphylococci from the indigenous flora of the human skin were not identical in their biotypes as previously described by Pelzer (1976). Only the investigation of all Staphylococci colonies from the culture plate can evaluate all biotypes of Staphylococci of the normal human skin flora, and can give the right quantitative correlation. Staphylococci were found to be sensitive and resistant up to four antibiotics, and one biotype did not show one type of antibiogram.

Adult↗