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PubMed1980

Mechanism of intrinsic penicillin-resistance in Staphylococcus aureus. Binding of penicillin G to the cytoplasmic membrane of resistant staphylococci.

In staphylococci (and other gram-positive bacteria) the phenotypical expression of intrinsic penicillin resistance as well as the frequency of this resistance are unknown. A permeability barrier in the cell wall, as it was established in gram-negative bacteria, is unlikely in staphylococci and was excluded by experiments with whole cells. Assuming that in staphylococci intrinsic resistance is also located in the cell envelope, the cytoplasmic membrane should be the site of responsibility. Therefore the binding of (14C)-penicillin G to the isolated membrane fraction of four staphylococcal strains resistant to penicillin G was studied. Two strains showed an additional resistance to methicillin, one of them was penicillinase-negative. Compared with two sensitive strains the penicillin binding was greatly reduced in the membranes of the resistant ones. This was not due to a loss of specific receptors. The maximum specific binding capacity of about 20 nmol of (14C)-penicillin G/g membrane protein was found in the resistant strains as well as in the sensitive controls. Furthermore penicillin G irreversibly bound also in the resistant bacteria. Differences, however, were found regarding the affinity of the binding sites for penicillin. In all resistant strains it was reduced by a factor of about 500. Our findings confirm the assumption that in staphylococci the mechanism of intrinsic penicillin resistance is located in the cytoplasmic membrane. They can best be explained when considering that not the penicillin binding components themselves but the membrane structure in their environment is altered thus preventing the access of the antibiotic to its site of action in the membrane. In addition, the homogeneity of our results indicates that intrinsic resistance to penicillin G is, contrary to current opinion, a general phenomenon in resistant staphylococci.

Binding Sites↗
PubMed1980

[Classification of coagulase-negative staphylococci isolated from urologic diseases].

A total of 174 strains of coagulase-negative staphylococci were isolated from the urine of urological patients in the USSR (Moscow) and the GDR (Wernigerode). Three schemes were used for identifying the species of the cultures (S. epidermidis and S. saprophyticus): the scheme proposed by the International Subcommittee for Taxonomy of Staphylococci and Micrococci (1976), the scheme of Digranes and Oeding (1975) and the scheme proposed by the authors of the present work. The use of the above-mentioned schemes allowed to identify 25, 33 and 68 per cent of the strains respectively. S. epidermidis prevailed among the "urological" staphylococci isolated in Moscow, and S. saprophyticus prevailed among the staphylococci isolated in Wernigerode. The insufficient effectiveness of the existing schemes for identifying the species of coagulase-negative staphylococci and the necessity of searching for new reliable biological tests are emphasized.

Coagulase↗
PubMed1980

The effects of cloxacillin on staphylococci phagocytosed by bovine neutrophils.

The effects of cloxacillin on staphylococci within neutrophils from the peripheral blood of cattle were examined. When cloxacillin was added to a preparation of intracellular staphylococci suspended in nutrient broth at 37 degrees C in the presence of lysostaphin, significantly more staphylococci were killed than in the controls without the antibiotic. Cloxacillin entered the neutrophils and made the intracellular staphylococci sensitive to lysis by lysostaphin when the neutrophils were disrupted. The intracellular action of cloxacillin was greater than when Hanks' balanced salt solution was the suspending fluid or when the broth was incubated at 4 degrees C. Failure to observe the effect in these circumstances was possibly due to a very low rate of metabolism in the staphylococci.

Animals↗
PubMedDate not supplied

[Teicoplanin and vancomycin susceptibility in Staphylococcus aureus and coagulase-negative staphylococci].

Members of the genera Staphylococcus are the most common pathogens found in the hospital environment and they are acquiring resistance to multiple drugs. PURPOSE--To evaluate the in vitro activity of teicoplanin and vancomycin against 195 strains of staphylococci isolated from in-patients. METHODS--One hundred strains of Staphylococcus aureus (50% methicillin-resistant) and 95 strains of coagulase-negative staphylococci (46.3% strains methicillin-resistant) were tested by the agar dilution and the disk diffusion techniques. RESULTS--All strains (100%) were susceptible to vancomycin, S. aureus strains presented MIC90 of 0.5 microgram/mL whereas strains of coagulase-negative staphylococci showed MIC90 of 1.0 microgram/mL. For teicoplanin, 98.5% of the strains were susceptible. MIC90 values were 0.5 microgram/mL for S. aureus strains, 2.0 micrograms/mL for coagulase-negative methicillin-susceptible staphylococci strains and 8.0 micrograms/mL for coagulase-negative methicillin-resistant staphylococci strains. CONCLUSION--From the microbiological point of view, the results showed a high potential for both drugs as therapeutic agents in staphylococcal infections due to multiresistant strains of hospital origin.

Cross Infection↗
PubMed1994

Carrier-status for nasal staphylococci does not predict infections in CAPD patients.

It has been reported that nasal carriage of staphylococci may contribute to infections of the continuous ambulatory peritoneal dialysis (CAPD) catheter exit site or cause peritonitis due to this pathogen. Recently, a nasal ointment to eradicate these bacteria in patients and staff has been marketed with the implication that this treatment may reduce infection rates. In this study, we investigated 37 patients treated with CAPD for a mean of 38.8 +/- 6.4 months. Presence of nasal carriage of staphylococci was assessed using standard nasal swab techniques and related to bacteria identified at the time of previous infections. Results were analyzed using Spearman rank order correlation and linear regression analysis. In 119.5 patient years at risk, 50 infections with staphylococci (24 episodes of peritonitis and 26 exit-site infections) were evaluated. Nineteen patients were carriers of S. aureus or S. epidermidis; 6 patients were carrying both species. There was no correlation of current nasal carriage of staphylococci with previous infection. Although 23 of 37 patients were carriers, 14 of these never had infections due to nasal staphylococci. Only in 14 of 50 infections were bacteria species the same in the nose and at the site of infection. We conclude that prospective trials demonstrating a reduction of CAPD-related infections are needed before general use of prophylactic nasal antibiotic treatment can be recommended in these patients.

Adult↗
PubMed1993

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

The study was aimed at establishment whether antagonistic influence between physiological oral cavity bacterial flora and staphylococci do exist and whether they influence on quantity of staphylococci in oral cavity environment. In samples of saliva taken from group of 11-13 year old children and a group of adults of both sexes, determinations were performed regarding total number of bacteria, number and percentage of bacteria inhibiting in vitro growth of standard indicator strain Staphylococcus aureus Oxford 209P and total number and percentage of staphylococci (together coagulase-positive and/or coagulase-negative). It was found that in each saliva sample bacteria inhibiting the indicator strain are present and their mean percentage is significantly higher in children than in adults and amounts respectively 47.1 +/- 28.5 and 35.0 +/- 20.3 (p = 0.0316). Higher percentage of antagonistic bacteria in children is associated with lower percentage of staphylococci in bacterial flora of saliva. Statistical analysis has confirmed existence of negative correlation, both linear and ranking, between the number of antagonistic bacteria and percentage of staphylococci in the saliva. This correlation is more strongly expressed and significant in children than in adults and linear correlation coefficient of Pearson amounts respectively to r = 0.7521 (p < 0.0005) and r = 0.3325 (p < 0.05). These results indicate that antagonistic bacterial flora is a significant factor limiting quantity of staphylococcal population in human oral cavity, especially in children.

Adolescent↗
PubMed1993

[Antagonism between oral cavity streptococci and staphylococci].

The subject of this study was investigation of quantitative relations between streptococci, lactic acid bacilli and actinomycetes and staphylococci present in the oral cavity. It was found that in each tested sample of saliva streptococci are present which inhibit growth of an indicator strain Staphylococcus aureus 209P. Percentage of such streptococci varies from 11.1% to 100% (mean value 52.9 +/- 19.7%). There is a negative correlation between number of streptococci and staphylococci in samples of saliva delivered from the same oral cavity. Pearson's linear correlation coefficient was r = -0.7962 (p < 0.0001), and Spearman's correlation rank was rs = -0.7667 (p < 0.0001). Lactic acid bacilli were inhibiting growth of staphylococci only in conditions in which there were not neutralized by organic acids produced by these microorganisms. Actinomycetes had no influence at all on growth of these microorganisms. These results suggest that streptococci are responsible for antagonistic properties of oral cavity bacterial flora in relation to staphylococci. Numbers of streptococci conditions size of staphylococcal population in this environment. Staphylococci practically exert no antagonistic activity against cohabiting with them streptococci.

Adult↗
PubMed1977

["Clumping factor"-reactions using staphylococci after their extraction with guanidiniumchloride (author's transl)].

Staphylococci of strain K 807 (ATCC: 31243) have much "clumping factor" (CF) on their surface. Extraction of the staphylococci with 6 M guanidinium chloride, removed all soluble substances, including coagulase, without reduction in CF-activity. The extracted staphylococci proved to be most suitable for the quantitative determination of fibrinogen and fibrin degradation products in a microtiter procedure (fig. 2). The CF-test with staphylococci of strain K 807 was more sensitive compared with the hitherto used strain Newman D2C (table 1). After staining with "Astrazonrot (BBL)" no loss of CF occurred. With the stained staphylococci the CF-reactions became more distinctly visible and gave sharp endpoints.

Agglutination↗
PubMed1998

Evaluation of an acriflavine disk assay for differentiating Staphylococcus aureus from other staphylococci isolated from bovine milk.

OBJECTIVE: To develop an acriflavine disk assay for identification of Staphylococcus aureus and to test whether the acriflavine disk assay could be used to differentiate S aureus from other staphylococci isolated from bovine milk samples. DESIGN: Prospective study. SAMPLE POPULATION: 882 staphylococcal isolates from bovine milk samples and 3 S intermedius isolates from dogs. PROCEDURE: Paper disks saturated with various amounts of acriflavine were used in a growth inhibition assay to determine the amount of acriflavine that would most reliably differentiate S aureus from other staphylococci. For all isolates, hemolytic pattern, results of tube coagulase tests after 4 and 24 hours of incubation, growth on acriflavine-supplemented media, results of an acriflavine disk assay, and results of an automated identification system were determined. RESULTS: 10 micrograms of acriflavine/disk was determined to be the most appropriate concentration for use in the assay. All 112 isolates identified as S aureus by the automated identification system were resistant to this concentration of acriflavine, and only 1 of 236 isolates identified as non-S aureus staphylococci was resistant. There was substantial agreement between results of using the acriflavine disk assay as a diagnostic criterion for differntiating S aureus isolates from non-S aureus staphylococci and results of the automated identification system. Agreement between results of determining hemolytic pattern and results of other diagnostic tests was only moderate. CLINICAL IMPLICATIONS: The acriflavine disk assay, using 10 micrograms of acriflavine/disk, was a practical, accurate method for differentiating S aureus isolates from non-S aureus staphylococci.

Acriflavine↗
PubMed1997

Molecular evolution of multiply-antibiotic-resistant staphylococci.

Methicillin-resistant Staphylococcus aureus (MRSA) is an intractable nosocomial pathogen. The chemotherapeutic intransigence of this organism stems from its predilection to antimicrobial resistance as a consequential response to selective pressures prevailing in the clinical environment. MRSA isolates are frequently resistant to all practicable antimicrobials except the glycopeptide, vancomycin. Although antimicrobial resistance sometimes arises via chromosomal mutation, the emergence of multiply-antibiotic-resistant staphylococci is primarily due to the acquisition of pre-existent resistance genes; such determinants can be encoded chromosomally or by plasmids and are often associated with transposons or insertion sequences. Clinical staphylococci commonly carry one or more plasmids, ranging from small replicons that are phenotypically cryptic or contain only a single resistance gene, to larger episomes that possess several such determinants and sometimes additionally encode systems that mediate their own conjugative transmission and the mobilization of other plasmids. The detection of closely related plasmids, elements and/or genes in other hosts, including coagulase-negative staphylococci and enterococci, attests to interspecific and intergeneric genetic exchange facilitated by mobile genetic elements and DNA transfer mechanisms. The extended genetic reservoir accessible to staphylococci afforded by such horizontal gene flux is fundamental to the acquisition, maintenance and dissemination of staphylococcal antimicrobial resistance in general, and multiresistance in particular.

Drug Resistance, Microbial↗
PubMed1990

The contribution of mammary infections by coagulase-negative staphylococci to the herd bulk milk somatic cell count.

Quarter foremilk samples were taken at 2-3 weekly intervals for several years in an experimental herd comprising about 45 cows. The samples were submitted to bacteriological analysis and somatic cell counting. The most prevalent quarter infections from 1982 to 1988 were by coagulase-negative staphylococci (15-20% of all the quarters sampled). Most of these (75.6%) persisted until drying-off. Dry cow therapy eliminated 86.5% of these infections. Comparison of udder quarters within cows, involving 775 samples from pairs of non-infected quarters and quarters infected by coagulase-negative staphylococci, yielded geometric means of somatic cell counts of 210,000 and 420,000 cells/ml, respectively. The correlation (r = 0.87) between the herd bulk milk somatic cell count (SCC) and its estimation from the quarter milk somatic cell count performed on the same day allowed us to evaluate the contribution of the different categories of quarters, according to their infection status, to the herd bulk milk SCC. Quarters infected by a major pathogen (8.5% of samples) gave rise to 46.6% of the total number of cells, while quarters infected by coagulase-negative staphylococci (17.8% of samples) gave rise to 18.1%. Although coagulase-negative staphylococci represented only a secondary source of somatic cells as compared to major pathogens, they were not a negligible source considering the threshold of 300,000 somatic cells advocated for herd milk of good quality.

Animals↗
PubMed1984

New aspects of staphylococcal infections: emergence of coagulase-negative staphylococci as pathogens.

In contrast to the well-established pathogen Staphylococcus aureus, the coagulase-negative staphylococci, formerly collectively called S. epidermidis, were until recently regarded as harmless commensals. During the last two decades, however, the coagulase-negative staphylococci have clearly emerged as pathogens in patients carrying artificial devices, such as prosthetic heart valves, hip prostheses and cerebrospinal fluid shunts, and in patients with compromised host defenses such as premature neonates and cancer and transplant patients. The present paper reviews current insights on classification, bacteriology, pathogenic potential and virulence factors of coagulase-negative staphylococci. In addition, the role of host defense factors in resistance to staphylococcal infection is summarized as well as the main features of the clinical syndromes in which coagulase-negative staphylococci are involved.

Antibodies, Bacterial↗
PubMed1999

[Preoperative infection prophylaxis with 1% polyvidon-iodine solution based on the example of conjunctival staphylococci].

BACKGROUND: Most germs causing postoperative endophthalmitis derive from the conjunctival bacterial normal flora. Postoperative endophthalmitis is often induced by staphylococcal germs. The application of polyvidone-iodine solution to the conjunctiva is one possibility to reduce potential endophthalmitis-causing bacteria. The aim of this study was to evaluate the effectiveness of 1% polyvidone-iodine solution concerning the reduction of colonization with staphylococci in the course of intraocular surgery. This is to evaluate the effectiveness of 1% polyvidone-iodine solution concerning coagulase-negative and positive staphylococci. PATIENTS AND METHODS: Patients with intrabulbar surgery (300) had three conjunctival swabs taken: the first immediately prior to preoperative preparation in the operating theatre, following in-patient application of antibiotic eye drops (Polymyxin-B-sulfat, Neomycinsulfat and Gramicidin in combination); the second swab was taken after antisepsis with polyvidone-iodine before opening the conjunctiva. At the end of surgery the third smear was taken. RESULTS: In 30.3% staphylococci were isolated from eyes before disinfection. Some patients (7.7%) were staphylococci-positive after disinfection; 5.3% of the patients showed staphylococcal growth at the end of surgery. To evaluate the effectiveness of polyvidone-iodine 1% solution we compared the first and the second smear (Mc Nemar). We found a statistically significant reduction (P < 0.001). At the end of surgery the conjunctival colonization with staphylococcal germs remained statistically significant reduced (P < 0.001). The mean operation time was 37 +/- 24 min. CONCLUSIONS: We concluded that a significant reduction of a staphylococcal colonization can be achieved by preoperative application of polyvidone-iodine (1%) (P < 0.001). Even at the end of surgery the effect of 1% polyvidone-iodine solution held.

Anti-Bacterial Agents↗
PubMed1999

Use of the polymerase chain reaction for rapid detection of high-level mupirocin resistance in staphylococci.

The minimum inhibitory concentrations (MICs) of mupirocin were determined by the E test (AB Biodisk, Sweden) and the agar dilution method for 107 staphylococci. The organisms consisted of 34 coagulase-negative staphylococci and 73 methicillin-resistant Staphylococcus aureus. Polymerase chain reaction (PCR) primers designed to amplify a 456 bp region of the plasmid-borne isoleucyl tRNA synthetase gene (ileS-2), responsible for high-level mupirocin resistance in staphylococci, were used on DNA preparations from these isolates. Isolates with high-level mupirocin resistance due to the ileS-2 gene should be PCR positive. There was close correlation between the E test and agar dilution MIC values, with only two strains differing by more than two serial dilutions. Most (51 of 54 strains) of the high-level resistant strains (MIC>256 microg/ml) were resistant to the highest concentration of mupirocin tested (1024 microg/ml). PCR correctly classified all but four (96%) of the isolates in accordance with the results of agar dilution. All four isolates that gave discrepant results were methicillin-resistant Staphylococcus aureus. Two of these were PCR positive, yet the MIC of mupirocin for these strains was <0.06 microg/ml; on prolonged incubation they produced halos within the inhibition zone on agar diffusion testing, suggesting that the phenotypic results may have been erroneous. One of 54 isolates for which the MIC exceeded 256 microg/ml was PCR negative when tested by the original methodology, but a 456 bp product was produced when retested using a lowered annealing temperature. One isolate for which the MIC of mupirocin was 16 microg/ml by agar dilution and 8 microg/ml by the E test was positive by PCR. PCR of the ileS-2 gene is a useful, rapid method for detecting high-level mupirocin resistance in staphylococci.

DNA, Bacterial↗
PubMed1982

Biochemical characterization of staphylococci isolated from goats.

Caprine strains of staphylococci show strong and early results in carbohydrate fermentation tests. Their ability to produce DNase and acetoin is weak but they possess a reasonably high degree of phosphatase activity. All the 82 isolates of Staphylococcus aureus isolated from clinically healthy and sick goats produced acid from D-(+)-glucose aerobically at 37 degrees C within 24 h, 98.8% fermented both D-mannitol and maltose, 98.7% fermented sucrose, and 81.7% fermented D-(+)-xylose with acid production, but none fermented L-sorbose. Of the ten coagulase-negative staphylococci characterized to be of animal origin, three produced DNase, but none fermented dulcitol and L-sorbose. All fermented D-(+)-glucose, maltose and D-mannitol, eight fermented D-(+)-xylose and D-sorbitol with acid production. Whilst other coagulase-positive and coagulase-negative staphylococci showed different antibiotic susceptibility patterns, the ten coagulase-negative staphylococci characterized to be of animal origin showed similar antibiotic susceptibility patterns.

Animals↗
PubMed2006

[Use of BioRad plating agar MRSASelect for the daily detection of methicillin resistant staphylococci isolated from samples taken from blood culture bottles].

Within a medium size general biology laboratory, it is not always easy to set up rapid methods for detection of methicillin-resistant staphylococci (detection of the mecA gene or PLP2a). Since we already use BioRad chromogenic plating agar MRSASelect for the detection of carriers of methicillin resistant Staphylococcus aureus, we wanted to test its use on samples taken from blood culture bottles. Between December 2004 and October 2005, all the blood bottle cultures that detected positive by direct examination for Gram positive cocci and suspected to be staphylococci, that is 45 pairs of blood cultures and 3 joint aspirations, were inoculated on quarter plates of both MRSASelect and standard non-selective agar. After culture, they were screened by the disc method. No mismatch was observed between the cultures themselves or the highlighting of methicillin resistance in either Staphylococcus aureus isolates or for coagulase-negative staphylococci, regardless of species. Furthermore, the red colour of Staphylococcus aureus on the medium allowed visualisation of the colonies after only about ten hours incubation, thus giving the clinician rapid warning of suspected methicillin resistant Staphylococcus aureus. In addition, in polymicrobial cultures the different colour of the colonies of Staphylococcus aureus (red) and coagulase-negative staphylococci (white) is extremely useful.

France↗
PubMed1997

Hydrolysis of esters by staphylococci.

The objective of this work was to characterize the hydrolysis of esters by staphylococci in order to understand if they could contribute to the release of free fatty acids in sausage. Cell-free extracts and extracellular concentrates of staphylococci were examined for esterase activities against p-nitrophenyl esters and for lipolytic activities against triolein. Staphylococci showed intracellular and extracellular esterase activities with different esterase electrophoretic patterns. Cell-free extracts of S. xylosus, S. warneri and S. saprophyticus preferentially hydrolysed p-nitrophenyl butyrate whereas their extracellular concentrates were mainly active against p-nitrophenyl butyrate, p-nitrophenyl caproate and p-nitrophenyl caprylate. In addition their extracellular concentrates hydrolysed triolein. The two strains of S. carnosus differed as they did not show pronounced p-nitrophenyl substrate specificity and did not hydrolyse triolein. Staphylococci hydrolysed esters at a high rate between 15 and 25 degrees C; acidic conditions inhibited the hydrolysis. The hydrolysis was also reduced when the water activity was decreased by addition of polyethylene glycol or glycerol.

Esterases↗
PubMed1981

Relationship of somatic cell count and cell volume analysis of goat's milk to intramammary infection with coagulase-negative staphylococci.

The prevalence of intramammary infection in 4 commercial goat herds was studied in conjunction with electronic somatic cell count and volume analysis determined using a Coutler Counter and volume analyser. Neither streptococci nor mycoplasma were isolated from any half and the prevalence of intramammary infection with Staphylococcus aureus ranged from 0 to 3% between herds. For coagulase-negative staphylococci the range from infected halves was 36-71%. There was no significant difference between the mean total microscopic somatic cell count for halves infected with coagulase-negative staphylococci and those free from infection. A similar trend was observed for electronic somatic cell counts although the mean electronic cell count was greater than the mean total microscopic count on the 2 occasions that they were compared. The correlation coefficients between the 2 cell counting methods were 0.86 and 0.94. Between herds there were significant differences in mean electronic somatic cell count, with herd means ranging from 438 x 103 to 1684 x 103 cells/ml. In 2 of the 4 herds studied, milk samples from halves infected with coagulase-negative staphylococci had a significantly higher prevalence of cell volume distributions with a modal cell volume between 65 mu 3 and 100 mu 3. This was attributed to a higher proportion of polymorphonuclear neutrophils. Use of electronic somatic cell count and cell volume analysis were considered of little value in predicting infection caused by coagulase-negative staphylococci as there was a high proportion of false negative and false positive predictions.

Animals↗