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PubMed1997

Dynamics of intramammary infection in the sheep caused by coagulase-negative staphylococci and its influence on udder tissue and milk composition.

Over an entire lactation 891 milk samples were collected from 99 ewes in a well-managed dairy flock. Coagulase-negative staphylococci were isolated from 53 (5.9 per cent) of the samples, with 13 (6.6 per cent) of the glands giving coagulase-negative staphylococci in two or more consecutive samples. When a somatic cell count threshold of 6 x 10(5)/ml of milk was adopted as an indication of inflammation, 30 of the milk samples collected during early and mid-lactation, which contained coagulase-negative staphylococci, were considered to come from glands suffering subclinical mastitis. In five glands subclinical mastitis persisted for the entire lactation. A comparison of somatic cell counts measured with the fossomatic or Coulter counters suggested that the former gave the most reliable values, particularly in late lactation. After the experimental infection of 20 glands of meat breeds with coagulase-negative staphylococci, five glands remained infected for all 49 days of observation and seven glands excreted bacteria intermittently. Irrespective of the presence of coagulase-negative staphylococci in the sample, the composition of the milk from the challenged glands was significantly modified (P < 0.0001 for the infected, and P < 0.01 for the uninfected glands). Fat and protein concentrations were increased and lactose decreased, suggesting that although coagulase-negative staphylococci could not always be isolated, they persisted in many of the challenged glands and continued to influence the physiology of the gland. This possibility was supported by the presence of severe damage to the udder tissue of glands in which bacteria had been shown to be present for long periods.

Animals↗
PubMed1982

Human alveolar macrophage cytophilic immunoglobulin G-mediated phagocytosis of protein A-positive staphylococci.

Human alveolar macrophages (AM) have recently been reported to ingest and kill a strain of Staphylococcus (502A) in the absence of opsonins. To further investigate the mechanism of non-opsonic recognition, we studied phagocytosis of 23 clinical and laboratory strains of S. aureus and Staphylococcus epidermidis by AM, and by blood polymorphonuclear leukocytes (PMN) and monocytes (MN). In the absence of opsonins, AM phagocytized 18 protein A-positive but not 5 protein A-negative strains of staphylococci, and the efficiency of phagocytosis directly correlated with the amount of protein A present in the bacterial cell wall (r = 0.86, P less than 0.001). Furthermore, AM rosetted around protein A-coated Sepharose beads, but not around beads without protein A. In contrast, PMN did not phagocytize nonopsonized staphylococci, and did not rosette around either type of Sepharose. MN phagocytized protein A-positive staphylococci, but much less efficiently than AM, and showed some rosetting around protein A-coated Sepharose. The nature of the AM receptor for protein A-positive staphylococci was studied. The surface of AM was positively stained with fluorescein-conjugated antibody to human IgG, but not with IgA- or IgM-specific conjugates. No such surface-immunoglobulins were detected on PMN, and MN were only weakly positive for surface IgG. Pretreatment of AM with F(ab')2 fragments specific for human IgG (anti-Fc) inhibited subsequent phagocytosis of protein A-positive staphylococci. There was no evidence that the AM surface IgG was aggregated or immunecomplexed. From these studies we conclude that human AM possess cytophilic IgG antibodies, which can function as receptors for phagocytosis of protein A-positive staphylococci.

Animals↗
PubMed2002

Distribution of mecA-harboring staphylococci in healthy mares.

The prevalence of staphylococci that harbor the mecA gene responsible for methicillin resistance was examined in healthy breeding mares. Staphylococci often cause diseases of horses such as metritis, keratitis, and abscess. Methicillin-resistant staphylococci would make antibiotic treatments ineffective, so it may be significant to know the distribution of mecA-harboring staphylococci in mares. Isolation of mecA-harboring staphylococci was achieved from nares and pasterns of 100 mares in Hokkaido, Japan. From 13% of the mares, mecA-harboring staphylococci, including 15 isolates of Staphylococcus sciuri and 3 of Staphylococcus lentus, were isolated. Isolates of S. sciuri were found to be genetically polyclonal by pulsed-field gel electrophoresis. These isolates produced no PCase and showed low or no resistance to beta-lactam and other classes of antibiotics. Distribution of staphylococcal species and levels of antibiotic resistance were found to be different between isolates from the present mares and those previously reported from riding-horses. Antibiotic pressure may lead to these differences. In addition, it appears that mecA-harboring S. sciuri may be native to horses.

Animals↗
PubMed1981

[Isolation of coagulase-positive staphylococci from cheese and ice-cream samples sold in Ankara and some biochemical properties of the isolates].

Coagulase-positive staphylococci were isolated from different kinds of cheese and ice-cream sold in Ankara and some biochemical properties of these isolates were determined. 55 cheese, 52 ice-cream (107 samples) were examined for the presence of coagulase-positive staphylococci. Baird Parker Medium was used and 26 samples constituting of 13 cheese and 13 ice-cream were found to be contaminated with coagulase-positive staphylococci and ratio of the contaminated samples to the total was calculated as 24.3%. Highest count was determined to be 176, 166/g in Izmir Tulum Cheese, whereas none of the other tulum cheese samples yielded this bacteria. In general, coagulase-positive staphylococci of cheese samples were higher than ice-cream samples. Among the ice-cream samples highest coagulase-positive staphylococci count was obtained in nutty ice-cream. From the 26 contaminated samples 164 coagulase-positive staphylococci were isolated. Results indicate that an important number of the coagulase forming isolates were also phosphatase positive, forming pigment and haemolysin, able to utilize mannitol. No relation could be observed between the coagulase formation and ability to produce lysin.

Cheese↗
PubMed1995

Fluoroquinolone resistance in staphylococci: new challenges.

Staphylococci show only marginal susceptibility to the newer fluoroquinolones. Minimum inhibitory concentrations (MICs) for susceptible strains usually range from 0.25 to 2.0 mg/l. As a single mutational event involving the gyrase target or permeability diminishes fluoroquinolone susceptibility fourfold on average, such a mutation in staphylococci would lead to a clinical level of resistance. Therefore, it is not surprising that in some institutions, the use of fluoroquinolones has been quickly followed by greatly increased prevalence of fluoroquinolone-resistant staphylococci. The greatest increase in resistance has been seen among methicillin-resistant staphylococci although increased prevalence of resistance among Staphylococcus saprophyticus and other methicillin-susceptible staphylococci has also been reported. Clinical isolates of staphylococci recovered since the introduction of the fluoroquinolones fall into three fluoroquinolone susceptibility groups: susceptible (MIC < 0.5 mg/l), moderately resistant (MIC 0.5 to 4 mg/l) and highly resistant (MIC > 4 mg/l). The first group represents wild type strains while the second and third groups represent single- and multiple-step mutants, respectively. To prevent increasing prevalence of isolates in the second and third groups, it would be prudent to avoid use of quinolones whenever possible. However, when it is necessary, a fluoroquinolone, which achieves serum/tissue levels eight times the MIC of the infecting strain, should be used.

Anti-Infective Agents↗
PubMed1995

erm genes in erythromycin-resistant Staphylococcus aureus and coagulase-negative staphylococci.

Erythromycin-resistant S. aureus from general practice and a dermatology ward with a very high consumption of erythromycin was studied for ermA and ermC content by Southern blot analysis. The prevalence of these erm genes was also studied in coagulase-negative staphylococci from the same dermatology ward and in a collection of 15 S. aureus and 18 coagulase-negative staphylococci found in the same specimen from 15 different patients. ermA was only found as a chromosomal insert and ermC only on small plasmids. In erythromycin-resistant S. aureus from general practice ermC was responsible for 84% of erythromycin resistance, while 16% of the strains contained ermA. In 17 of 18 S. aureus strains from the dermatology ward a 2.5 kb plasmid contained ermC. Among 58 erythromycin-resistant coagulase-negative staphylococci only 2 (3%) had ermA, whereas 44 strains (76%) had ermC. ermA or ermC genes were common in S. epidermidis (36/38). However, in 20 isolates of erythromycin-resistant coagulase-negative staphylococci of other species, 10 had neither ermA nor ermC. ermC was the most common erm gene in both coagulase-negative staphylococci and S. aureus. In 11 of 15 patients with erythromycin-resistant S. aureus the co-isolated erythromycin-resistant coagulase-negative staphylococcus had another resistance mechanism, either another gene or a different phenotypic expression of the same gene. Resistance to pristinamycin, a streptogramin antibiotic only used in animals, was not found in S. aureus but was found in 14% of erythromycin-resistant coagulase-negative staphylococci.

Animals↗
PubMed1994

[Determination of the susceptibility of staphylococci and enterococci to plycopeptides by the E-test method].

E-test was evaluated by comparison with the reference agar dilution method on 15 enterococci and 15 staphylococci with variable resistance to glycopeptides and isolated from clinical samples: 15 enterococci with 3 glycopeptide-resistant (2 E. facalis and 1 E. faecium), 1 glycopeptide intermediate E. gallinarum and 11 glycopeptide-sensible E. faecalis; 15 staphylococci with 4 teicoplanine-resistant (1 S. aureus, 1 S. epidermidis and 2 S. hominis), 3 teicoplanin-intermediate (1 S. epidermidis, 2 S. haemolyticus) and 8 teicoplanin sensible strains (6 S. aureus, 1 S. epidermidis and 1 S. hominis). Repeatability (10 determinations by strain) and exactitude were tested for all strains. Our data shows very good results for repeatability and exactitude with the reference method except in the case of coagulase negative staphylococci and teicoplanin. Some technical problems appear in our experience: for staphylococci, a 48 h incubation is necessary to detect teicoplanin-intermediate strains but 24 h is sufficient for enterococci. E-test is expensive, require a strict methodology, but is a good method to detect glycopeptide resistance for staphylococci and enterococci except for coagulase negative staphylococci and teicoplanine.

Bacteriological Techniques↗
PubMed1993

[Susceptibility of methicillin-sensitive and methicillin-resistant staphylococci to ciprofloxacin].

Investigations were carried on 352 strains of Staphylococcus aureus and 105 strains of coagulase-negative staphylococci, isolated from various clinical materials and derived from some regions of the country. Methicillin-resistance was tested by an antibiotic dilution method in solid Mueller-Hinton medium with addition of 2% NaCl. Staphylococci with MIC higher than 4 micrograms/ml were considered as resistant. The same method for testing resistance to ciprofloxacin was used. Only one strain (S. aureus) was resistant to both ciprofloxacin and methicillin. All remaining strains of staphylococci were ciprofloxacin-susceptible. The MIC for all of them was not higher than 2 micrograms/ml, regardless of resistance to methicillin. Some slight differences in MIC50 and MIC90 values were found between MRSA and MSSA and they were, respectively, 1 microgram/ml and 0.25 microgram/ml, and 2 micrograms/ml and 1 microgram/ml. Mean MIC of ciprofloxacin for MRSA was 1.1 microgram/ml and for MSSA it amounted to 0.4 microgram/ml. Range of MIC was following: MRSA--0.12 microgram/ml--16 micrograms/ml and MSSA--0.12-2 micrograms/ml. Coagulase-negative staphylococci, both methicillin-resistant and methicillin-sensitive, exhibited same value for MIC50, MIC90 and MIC range and they were following: 0.5 microgram/ml, 1 microgram/ml and 0.12-1 micrograms/ml. Both groups differed slightly in mean MIC values which was 0.6 microgram/ml for methicillin-resistant strains and 0.47 microgram/ml for methicillin-sensitive staphylococci. It seems that within staphylococci isolated in Poland there is no correlation between resistance to methicillin and ciprofloxacin, which is frequently pointed out by other authors.

Ciprofloxacin↗
PubMed1993

In vitro activity of ceftriaxone and other cephalosporins against 602 clinical isolates of staphylococci from geographically diverse medical centers.

The in vitro activity of ceftriaxone and six additional antimicrobial agents (ceftizoxime, cefoperazone, cefuroxime, fleroxacin, ciprofloxacin, and trimethoprim/sulfamethoxazole) was assessed or 602 recent clinical isolates of staphylococci from six geographically distinct medical centers in North America. All seven antimicrobial agents were active (90-100% of strains susceptible) against oxacillin-susceptible (OS) strains of Staphylococcus aureus (OSSA) and coagulase-negative staphylococci (OSCNS) but had limited activity against oxacillin resistant (OR) staphylococci. Our assessment of the in vitro antistaphylococcal activity of ceftriaxone against contemporary isolates of Staphylococcus aureus and coagulase-negative staphylococci indicates that the activity versus OS staphylococci has not changed over the past decade despite widespread use of the drug. It appears that these agents will continue to be useful for empiric therapy in those centers in which OR strains are uncommon.

Academic Medical Centers↗
PubMed1988

Development of the quantitative micro-test for slime production by coagulase-negative staphylococci.

The macro-test for slime production by coagulase-negative staphylococci was adapted to a spectrophotometric micro-test assay to obtain more objective and quantitative information on slime production. A total of 135 isolates of coagulase-negative staphylococci (70 macro-test-positive and 65 macro-test-negative) were tested by both methods. The quantitative micro-test optical density readings were (mean +/- SD) 1.176 +/- 0.294 and 0.130 +/- 0.095 for the macro-test-positive and -negative groups, respectively. The micro-test was reproducible and demonstrated quantitative differences in slime production among the different species of coagulase-negative staphylococci. Aside from Staphylococcus epidermidis, the majority of the coagulase-negative staphylococci had very low optical density readings, indicating little or no slime production under the conditions employed in this assay. This test allows one to study the relative production of slime by different strains and species of coagulase-negative staphylococci, and may be useful in studying the effects of different conditions, such as antibiotic exposure, on slime production.

Bacterial Proteins↗
PubMed2006

Prosthetic valve endocarditis due to coagulase-negative staphylococci: findings from the International Collaboration on Endocarditis Merged Database.

Infective endocarditis due to coagulase-negative staphylococci is increasingly recognized as a difficult-to-treat disease associated with poor outcome. The aim of this report is to describe the characteristics and outcome of patients with prosthetic valve endocarditis (PVE) due to coagulase-negative staphylococci versus those of patients with PVE due to Staphylococcus aureus and viridans streptococci. Patients were identified through the International Collaboration on Endocarditis Merged Database. A total of 54 cases of coagulase-negative staphylococci PVE, 58 cases of S. aureus PVE, and 63 cases of viridans-streptococci-related PVE were available for analysis. There was no difference between the three groups with respect to the type of valve involved or the rate of embolization. However, heart failure was encountered more frequently with coagulase-negative staphylococci (54%) than with either S. aureus (33%; p=0.03) or viridans streptococci (32%; p=0.02). In addition, valvular abscesses complicated 39% of infections due to coagulase-negative staphylococci compared with 22% of those due to S. aureus (p=0.06) and 6% of those due to viridans streptococci (p<0.001). Mortality was highest in patients with S. aureus and coagulase-negative staphylococcal endocarditis (47 and 36%, respectively; p=0.22) and was considerably lower in patients with viridans streptococcal endocarditis (p=0.002 compared to patients with coagulase-negative staphylococcal endocarditis). The results of this analysis demonstrate the aggressive nature of coagulase-negative staphylococcal PVE and the substantially greater morbidity and mortality associated with this infection compared to PVE caused by other pathogens.

Aged↗
PubMedDate not supplied

Absence of factors associated with significant urinary tract infections caused by coagulase-negative staphylococci.

Coagulase-negative staphylococci, excluding Staphylococcus saprophyticus, have recently been implicated as pathogens in urinary tract infections, especially in catheterized patients. In order to evaluate any laboratory markers for significant isolates of coagulase-negative staphylococci, we prospectively studied 72 patients with significant, indeterminant, or contaminant urine isolates of coagulase-negative staphylococci. Patients in the three categories did not differ by age, sex, presence of a urinary catheter, or other instrumentation or likelihood of nosocomial acquisition. The isolates from these three groups of patients were similar in antibiotic susceptibility and ability to produce slime. Overall, slime-producing coagulase-negative staphylococci were more likely to be S. epidermidis than any other species, but slime production was not associated with presence of pyuria, symptomatic urinary tract infection, instrumentation, nosocomial acquisition, or multiple antibiotic resistance. In this prospective study, no demographic characteristics or laboratory markers of coagulase-negative staphylococci were associated with clinical significance, as defined by symptoms or the presence of pyuria.

Bacteriuria↗
PubMed2005

Investigation of aminoglycoside modifying enzyme genes in methicillin-resistant staphylococci.

Methicillin-resistant staphylococci may also be resistant to some other antibiotics as well as beta-lactams. In this study, co-existence of resistance to methicillin and aminoglycosides was genetically investigated in staphylococci. A total of 50 staphylococci from in-patients, 17 Staphylococcus aureus and 33 coagulase negative staphylococci (CNS) that contained mecA (gene encoding PBP 2a, an altered penicillin-binding protein) determined by polymerase chain reaction (PCR) were included in the study. Aminoglycoside modifying enzyme (AME) genes were investigated using multiplex-PCR. Aminocyclitol-6'-acetyltransferase-aminocyclitol-2''-phosphotransferase [aac(6')/aph(2'')] gene (encoding bifunctional acetyltransferases/phosphotransferases) was determined in 66% of the isolates, aminocyclitol-4'-adenylytransferase (ant(4')-Ia) gene (encoding phosphotransferases) in 24%, and aminocyclitol-3'-phosphotransferase (aph(3')-IIIa) gene (encoding nucleotidyltransferases) in 8%. Two isolates contained all these three genes. Thirty-six (72%) isolates had at least one of these genes. Three CNS and one S. aureus isolates sensitive to oxacillin had the mecA gene. In conclusion, a high rate of aminoglycoside resistance was determined in methicillin-resistant staphylococci. The aac(6')/aph(2'') was the most frequently detected.

Acetyltransferases↗
PubMed2005

The prevalence of methicillin-resistant staphylococci in healthy horses in the Netherlands.

Two hundred healthy horses housed at 23 different farms and one clinic and 42 persons in close contact with these horses were screened for the presence of methicillin resistant staphylococci. Samples were taken from the nose and the pastern of the horses and from the nose and throat of the humans and incubated in selective media. Isolates were identified by standard techniques and their susceptibilities were tested using an agar diffusion method. Methicillin-resistant strains were tested for the presence of the mecA gene by PCR. In 45 horses (22.5%) and 15 humans (35.7%) mecA positive staphylococci were found. All isolates were coagulase negative staphylococci, except for one methicillin-resistant Staphylococcus aureus isolated from a veterinarian. Staphylococcus sciuri was the predominant species found among the methicillin resistant staphylococci (MRS) in the horses, whereas S. epidermidis predominated in the humans. From the horses, often more than one species of MRS could be isolated, resulting in a total of 175 mecA positive equine isolates. The equine isolates were predominantly susceptible to most antimicrobials tested, whereas the human isolates showed more resistance. In conclusion, no methicillin-resistant Staphylococcus aureus was found in healthy horses in the Netherlands, but methicillin-resistant coagulase negative staphylococci were found frequently. Further studies are needed in order to investigate whether horses can be a reservoir for MRS or the mecA gene for humans.

Animals↗
PubMed1999

Effect of nitrate and incubation conditions on the production of catalase and nitrate reductase by staphylococci.

The objective of this work was to study the production of catalase and nitrate reductase by staphylococci in order to understand their role in lipid oxidation during sausage manufacturing. Catalase and nitrate reductase were measured in resting cells and supernatants of staphylococci grown in different conditions. All staphylococci (except S. warneri) synthetized nitrate reductase. In static condition, the synthesis was maximal during exponential growth phase, whereas in shaking condition, the synthesis was maximal at the beginning of stationary phase. The production of nitrate reductase was increased in presence of nitrate, this effect was particularly important for the two S. carnosus strains which exhibited the highest activity. For all staphylococci, the production of catalase was maximal at the end of the exponential growth phase. The lowest amount of catalase was produced by S. warneri and the highest by S. carnosus. Only S. xylosus 873 and S. saprophyticus 852 released high amounts of catalase in the supernatant growth. Staphylococci produced higher amounts of catalase in shaking conditions. Addition of nitrate in the growth media favoured the synthesis of catalase, with a pronounced effect for S. carnosus. Nitrate also favoured the release of catalase.

Animals↗
PubMed1990

Resistance of gram-negative bacilli and staphylococci from blood cultures to aminoglycoside antibiotics. Comparison of 3 in vitro investigations from Austria 1982-1988.

A total of 790 blood culture isolates was collected during 3 study periods in 1982/83, 1984/85 and 1987/88. Staphylococci were the most frequent bacteria in the first two periods (56.5% and 63%, respectively). During the last period, E. coli was the most frequent of all species (27%). Differences in the distribution of bacteria between the laboratories were considerable. In one laboratory in Vienna, coagulase-negative staphylococci dominated in all 3 study periods (32%, 33% and 47%). Susceptibility against gentamicin, tobramycin and netilmicin (MIC less than or equal to 4 mg/l), as well as against amikacin (MIC less than or equal to 8 mg/l) were determined by a microdilution method. The resistance rates against gentamicin (G) were 25%, 21% and 25%, against tobramycin (T) 27%, 19% and 25%, against netilmicin (N) 6%, 4% and 19%, and against amikacin (A), 5%, 2% and 19%. Most resistant strains were staphylococci (G 26%-41%, T 26%-46%, N 3%-31%, A 3%-36%), whereas gram-negative bacilli were more susceptible (G 12%-14%, T 7%-11%, N 7%-9%, A 1%-7.5%). The increase of resistance against netilmicin and amikacin in staphylococci was most striking. Nearly all those strain could be attributed to one laboratory in Vienna. Most of them were coagulase-negative staphylococci. In the first study period, the most frequent pattern was resistance against gentamicin and tobramycin, whereas in the last period resistance to all 4 aminoglycosides dominated. The study demonstrates considerable local differences in antibiotic resistance. Monitoring of antibiotic resistance in collaborative studies using standardized methods should be a valuable tool in planning strategies for controlling an epidemic spread of resistance.

Amikacin↗
PubMed1997

Multiplicity of the genes and plasmids conferring resistance to pristinamycin in staphylococci selected in an Algerian hospital.

In an Algerian hospital where pristinamycin (Pt) was extensively used for the treatment of chronic osteomyelitis and for prophylaxis in bone surgery, the prevalence of pristinamycin-resistant (PtR) staphylococci during a five-month period (20%) was higher than that among staphylococci isolated elsewhere in Algeria (4.5%). Analysis of 13 PtR staphylococci isolated in this hospital revealed a diversity of plasmids and genes conferring resistance to Pt and to related antibiotics. Most of the PtR staphylococci were unrelated: they belonged to either different taxa or types. Nevertheless, some of the unrelated staphylococci harboured structurally related plasmids carrying streptogramin resistance genes. Thus, these plasmids may have contributed to the dispersion of these genes.

Algeria↗
PubMed1997

Leukotoxic factors produced by staphylococci of ovine origin.

Leukotoxins produced by staphylococci, especially Staphylococcus aureus, have long been considered important virulence determinants. The present assay examined 26 strains of staphylococci isolated from sheep for their ability to produce factors leukotoxic to polymorphonuclear leukocytes deriving from ovine mammary glands. Twenty one strains were coagulase-negative staphylococci and five coagulase-positive. Of the coagulase-negative staphylococci 17 were isolated from subclinical mastitis and four from the teat skin. The coagulase-positive strains were isolated from clinical mastitis and caused death to 91-100% of the cells. The coagulase-negative strains isolated from subclinical mastitis caused death to less than 50% of cells, while those from the skin did not affect any cells. The concentration of active leukotoxins is an important staphylococcal virulence factor. Low production of leukotoxins or no production by coagulase-negative staphylococci may determine their ability to survive the mammary gland defenses or cause clinical mastitis.

Animals↗