Identification and characteristics of staphylococci isolated from lesions and normal skin of horses

One hundred and twenty eight strains of Staphylococcus from lesions, mostly of the skin, in horses were identified and compared with 29 strains isolated from the healthy skin. The pathogenic species Staphylococcus aureus, S. intermedius and S. hyicus were found almost exclusively in lesions. Other species such as S. xylosus and S. sciuri were more frequently found on the healthy skin than in lesions. The S. aureus strains formed a very heterogeneous collection. Many of these strains were staphylokinase positive and rapidly coagulated bovine plasma. Such strains are rarely found in other animals and man.     

Screening of Staphylococcus aureus, Staphylococcus intermedius, and Staphylococcus schleiferi isolates obtained from small companion animals for antimicrobial resistance: a retrospective review of 749 isolates (2003-04)

Companion animal staphylococcal isolate antibiograms were screened retrospectively to determine the frequency of methicillin-resistant (MR) infection by Staphylococcus aureus, Staphylococcus intermedius, and Staphylococcus schleiferi. Rates of MR were: S. aureus 35%, S. intermedius 17%, and S. schleiferi 40%. Frequency of isolation of methicillin-resistant S. aureus (MRSA) from dogs and cats was similar, whereas methicillin-resistant S. intermedius (MRSI) and methicillin-resistant S. schleiferi (MRSS) were significantly more common in dogs. MRSS was more commonly associated with superficial (skin and ear canal) infections, whereas MRSA was more commonly associated with deep infections. The MR strain resistance pattern to other classes of antibiotics was also investigated. MRSA was resistant to the most classes of antibiotics, followed by MRSI, while MRSS maintained the most favourable susceptibility profile. MR staphylococci may pose a significant risk to animal and public health. Therefore, to avoid selecting for resistant strains in cases of suspected staphylococcal infection, clinicians should consider culture and susceptibility testing early in the course of treatment.     

Indications for both host-specific and introduced genotypes of Staphylococcus aureus in marine mammals

Staphylococcus aureus is present in the marine environment and causes disease in marine mammals. To determine whether marine mammals are colonized by host-specific strains or by strains originating from other species, we performed multi-locus sequence typing on ten S. aureus strains isolated from marine mammals in the U.K., the Netherlands, and the Antarctic. Four new sequence types of S. aureus were discovered. S. aureus strains from a southern elephant seal (n=1) and harbour porpoises (n=2) did not cluster with known S. aureus strains, suggesting that they may be host species-specific. In contrast, S. aureus strains from harbour seals (n=3), other harbour porpoises (n=3), and a grey seal (n=1) clustered with S. aureus strains previously isolated from domestic ruminants, humans, or birds, suggesting that these S. aureus strains in marine mammals were introduced from terrestrial species.     

Antimicrobial resistance of feline staphylococci in south-eastern England

Staphylococcus aureus is reported as the predominant feline staphylococcal pathogen. There is concern that cats may transfer resistant staphylococci to humans. In this study, staphylococci were obtained from skin and mucosae of 20 domestic cats, 9 with lesions, and 10 healthy feral cats. Species were identified by DNase and API ID32 Staph tests. Of 187 isolates, 21.4% were coagulase-positive and predominately from lesional cats; 90% of these were Staphylococcus intermedius . Coagulase-negative species were isolated equally in all three groups. All isolates were susceptible to coamoxiclav, cephalexin and bacitracin. Twenty-two, including 18 coagulase-negative isolates, showed some resistance to cotrimoxazole, lincomycin, enrofloxacin or oxytetracycline. Two isolates were resistant to more than one antibiotic. More resistant isolates were obtained from feral cats ( P < 0.01). The results suggest that S. intermedius is the principal coagulase-positive species. Antibiotic resistance is generally low amongst feline staphylococci. Higher resistance amongst feral cats suggests exposure to environmental antibiotics.     

Phage typing coagulase-positive staphylococci from rooks and gulls

Phage typing was performed on 86 strains of Staphylococcus aureus and 25 strains of Staphylococcus intermedius from rooks and gulls with human, bovine, chicken and canine phages. Eighty per cent of the S aureus strains and 64 per cent of the S intermedius strains were typable. The S aureus biotype D strains of rook origin were specifically lysed at routine test dilution (RTD) by chicken phages from groups I or I + IV, by human phages belonging to groups I and M, and partly by canine phage 58. The other rook and gull S aureus strains did not show characteristic phage patterns. The S intermedius strains isolated from both species of birds could be typed only with canine phages and this correlated with their classification into biotypes. All the biotype 1 strains tested but only two of 12 biotype 2 strains were lysed with canine phages at RTD.     

Frequency and antimicrobial susceptibility of Staphylococcus species isolated from canine pyodermas

Specimens obtained from pyogenic skin lesions of 210 dogs were culturally examined for staphylococci. A total of 215 isolates of staphylococci were biotyped, using the biochemical tests contained in a commercial staphylococcal identification system. Of 201 coagulase-positive isolates, 197 were identified as Staphylococcus intermedius, 3 as S aureus, and 1 as S hyicus. Of 14 coagulase-negative isolates, 5 were identified as S epidermidis, 5 as S xylosus, 3 as S simulans, and 1 as S hominis. Antimicrobial susceptibility tests were done on all staphylococcal isolates, using the standard disk-diffusion method. Staphylococcus intermedius isolates were susceptible to cephalothin, methicillin, and gentamicin. Resistance to ampicillin, penicillin G, and tetracycline was frequent. Antibiotic resistance was not associated with the depth of skin infection. Resistance to ampicillin, penicillin, tetracycline, and trimethoprim-sulfamethoxazole was not associated with previous antibiotic use. Increased resistance to chloramphenicol, clindamycin, and erythromycin was associated with previous antibiotic therapy. Antimicrobial susceptibilities of the other Staphylococcus species isolated are reported, but the small numbers of these species precluded making meaningful comparison with S intermedius.     

Enhanced virulence of Staphylococcus aureus from bovine mastitis induced by growth in milk whey

The virulence towards mice of Staphylococcus aureus strains from bovine mastitis was enhanced upon growth in milk whey compared to homologous organisms grown in tryptic soy broth (TSB). In the mouse mastitis model, S. aureus grown in milk whey caused more severe lesions than homologous strains grown in TSB. Staphylococcus aureus strain F1440 grown in milk whey induced 75% mortality and local necrotic reaction in subcutaneously inoculated mice, whereas the homologous strain grown in TSB caused only 5% mortality and slight skin reaction. Extracellular capsule on milk whey-grown, S. aureus could not be demonstrated. However, diffuse type colony morphology could be correlated with an increased virulence of S. aureus towards mice.     

Distribution of staphylococcal species on clinically healthy cats

Among 827 isolates derived from 113 clinically healthy cats, 12 species of staphylococci were identified. Staphylococci were isolated from each cat and from 54.9% of the anatomic sites evaluated. A mode of 6 (range = 2 to 11) of the 11 anatomic sites evaluated per cat yielded staphylococci. A mode of 8 (range = 2 to 12) isolates were found per cat. Staphylococcus simulans was the most isolated (43.9% of total) coagulase-negative species. Moreover, S simulans was the most isolated species from each of the 11 sites evaluated and, except for the mouth and haircoat, comprised greater than 50% of the isolates from each site. Staphylococcus intermedius was the most isolated (13.5% of the total) coagulase-positive species. Three other species (S epidermidis, S xylosus, and S aureus) comprised 32.2% of the isolates, and 7 species (S haemolyticus, S hominis, S hyicus, S capitis, S warneri, and S saprophyticus) comprised 10.4% of the isolates. Six species (S intermedius [96 of 112 isolates], S haemolyticus [20 of 22], S sciuri [17 of 18], S warneri [10 of 13], S hyicus [10 of 10], and S capitis [7 of 8]) were isolated primarily from household cats. Only 1 species, S xylosus (75 of 87), was isolated primarily from cattery cats. Haircoat specimens (n = 452) yielded 508 isolates (61.4% of the total) distributed among all 12 staphylococcal species and included greater than 50% of the isolates of all species other than S simulans and S sciuri. A more heterogeneous population of staphylococci was isolated from household cats than was isolated from cattery cats.     

Interaction of sub-epithelial connective tissue components with Staphylococcus aureus and coagulase-negative staphylococci from bovine mastitis

Staphylococcus aureus and coagulase-negative staphylococci (CNS) isolated from bovine mastitis were examined for their ability to interact with 125I-labelled fibronectin, fibrinogen and type II collagen. Their relative surface hydrophobicity and production of extracellular capsule were also investigated. Almost all S. aureus strains bound fibronectin (mean value 23%), fibrinogen (mean value 12%) and type II collagen (mean value 16%). CNS bound fibronectin (mean value 6%) and type II collagen (mean value 7%), but not fibrinogen (mean value 2%). The specificity of binding of these proteins to S. aureus strain F1440 and to coagulase-negative Staphylococcus chromogenes strain BO52 was studied by adding an excess of unlabelled proteins. Fibronectin and collagen binding were observed to be specific, varying between 50 and 75%, whereas the specificity of fibrinogen binding to S. aureus strain F1440 was lower (26%). Most of the S. aureus strains (63%) showed very high surface hydrophobicity (autoaggregation) or lower hydrophobicity (29% of the strains) and the rest were hydrophilic. None of the CNS strains autoaggregated, 44% were classified as hydrophilic strains. Hydrophilic strains (except the reference strains) did not show extracellular capsule production. However, the encapsulated (reference) strains showed low binding to these proteins as compared to their unencapsulated variants. Pre-treatment of S. aureus strain F1440 and S. chromogenes strain BO52 with trypsin decreased their fibronectin binding capacity and surface hydrophobicity, whereas pre-treatment with bovine milk (except on collagen binding to strain F1440) did not significantly affect binding to these proteins. These data indicate that S. aureus and CNS isolated from bovine udder infection have the ability to bind to tissue matrix and plasma proteins which may be exposed in the traumatized or toxin-damaged udder epithelial lesions.     

Staphylococcal colonization of mucosal and lesional skin sites in atopic and healthy dogs

Staphylococcal colonization was compared in healthy dogs and in dogs with atopic dermatitis. Bacterial swabs were collected from the nasal mucosa, ear and perineum of 43 healthy and 24 atopic dogs and also from potentially infected skin lesions of the atopic dogs. Coagulase positive staphylococcal isolates were identified to the species level. At the time of this study Staphylococcus intermedius was considered a single species but has since been recognized as comprising at least three species with canine isolates believed to belong to Staphylococcus pseudintermedius . Of atopic dogs, 87.5% were colonized with S. intermedius compared to only 37.2% of healthy dogs. The ear was the only carriage site that showed any significant difference in S. intermedius isolation between healthy and atopic dogs. The perineum represented the most frequently colonized mucosal site for both groups. Sampling the nasal mucosa alone identified 71.4% of atopic and 37.5% of healthy S. intermedius carriers. Inclusion of a perineal swab identified 100% of atopic and 93.8% of healthy carriers. S. intermedius was isolated from all the lesional sites sampled from atopic dogs. Significantly fewer dogs were colonized by Staphylococcus aureus than S. intermedius , and there was no significant difference between S. aureus colonization of atopic and healthy dogs. S. aureus was not recovered from any lesions in atopic dogs. The results show that S. intermedius carriage is more prevalent in atopic dogs compared to healthy dogs and that to identify staphylococcal carriers both the nasal mucosa and the perineum should be sampled.     

High and low virulence Staphylococcus aureus strains in a rabbit skin infection model

In the present study, an in vivo rabbit skin infection model was developed to reproduce the lesions caused by high and low virulence Staphylococcus aureus strains from rabbits. "O"-shaped dermal skin lesions were induced on the shaved flanks of anaesthetised rabbits using a tattoo pin and pincers. The induced lesions on the flanks of four groups of 10 rabbits were then inoculated by topical application of 0.1 ml of 10(8)cfu S. aureus bacteria. One group was inoculated with a typical high virulence (HV) S. aureus strain from rabbits, one group received an atypical HV strain and two groups were inoculated with low virulence (LV) strains. Five animals were kept as negative controls. The development, appearance and size of abscesses were scored daily for a period of 2 weeks. The infection model showed reproducible results for the different S. aureus inoculation groups. Inoculation of the skin with the typical HV strain resulted in significantly larger abscesses than those caused by the LV strains. The atypical HV strain caused abscesses of a size intermediate to that obtained with the HV and LV strains. In rabbits infected with LV strains, most of the lesions had healed by day 14 post-inoculation. The devised infection model is able to reliably reproduce the virulence properties of HV and LV S. aureus strains.     

The dynamics of Staphylococcus aureus intramammary infection in nine Danish dairy herds

The aim of the present study was to examine the diversity of Staphylococcus aureus isolates from bovine intramammary infections (IMI) in nine dairy herds, and compare these with isolates from other sites on the cows by phage- and ribotyping. Whether colonisation of milkers with S. aureus could be a source of infection for bovine IMI was investigated. In addition, 100 epidemiologically unrelated S. aureus isolates from asymptomatic human carriers were also phage- and ribotyped to compare the human and bovine reservoir of S. aureus in Denmark. A total of 625 S. aureus isolates from bovine IMI, bovine skin lesions, milking personnel, and non-farm-related human carriers were included in the study. Certain types predominated in one or several herds during the study period of one-and-a-half to two years, whereas the presence of other types was of a more sporadic nature. Within the individual herds, there was a close correspondence between ribo- and phage types of S. aureus isolated from bovine intramammary infections and skin lesions. Isolates from milking personnel, however, were not identical to any of the predominant intramammary strains. Furthermore, several of the isolates from milking personnel showed ribo- and phage patterns identical to S. aureus isolates from human carriers. The findings of the present study underline the importance of strict milking hygiene and improvement of current mastitis therapy. The results support the hypothesis that some S. aureus mastitis strains are more contagious, virulent or persistent than others. The human reservoir of S. aureus does not play a major role as a source of bovine intramammary infections.     

金黄色葡萄球菌α-溶血素基因的克隆与序列分析

参考Gary S Gray和Michael Kehce在《传染与免疫》杂志上发表的关于金黄色葡萄球菌α溶血素蛋白的基因序列,设计合成1对引物,从分离自牛体的野生株金黄色葡萄球菌中提取细菌总DNA,对α溶血素蛋白基因进行PCR扩增,产物经琼脂糖凝胶电泳分析,呈现1条约960 bp的条带,回收纯化后,将其克隆至pMD18 T质粒载体中,进行核苷酸序列分析,然后与报道的α溶血素蛋白基因进行比较。结果表明:所鉴定的野生株金黄色葡萄球菌的α溶血素蛋白基因序列与报道的核苷酸的同源性高达99.99%以上,证实为金黄色葡萄球菌Wood 46株α溶血素蛋白基因。     

Species of Staphylococcus isolated from animal infections

One hundred randomly selected clinical strains of staphylococci were identified by species using a commercial micromethod system. Eight species of staphylococci were identified. Staphylococcus intermedius was the most frequent (n = 74) species identified and accounted for 70/74 (94.6%) of the coagulase-positive strains and 70/79 (88.6%) of the total isolates from dogs. Other species identified, in order of their frequency, included S. epidermidis (8), S. aureus (7), S. simulans (4), S. sciuri (2), S. xylosus (2), S. hyicus (2) and S. saprophyticus (1). These results show that at least 8 different species of staphylococci can be recovered from animal infections and that coagulase-positive species such as S. intermedius may be more common than S. aureus. The relative significance of these other species in animal infections needs to be assessed.     

FC-44 The therapeutic effect of selamectin and ivermectin regimens in canine sarcoptic mange

Worldwide, sarcoptic mange in cats is seldom reported, and then only in sporadic individual cases. We describe an epidemic in a household with a dog and 25 cats. From September 2002, the dog was repeatedly treated with ivermectin for sarcoptic mange. The diagnosis was confirmed by skin scrapings. Fifteen months later, cats from the same household were diagnosed with severe sarcoptic mange. Twenty-one of the cats were euthanized and necropsies were performed. Skin samples were taken from all cats from different body sites for histology, and skin scrapings were examined for ectoparasites. Samples for bacterial and dermatophyte culture were taken from six cats. Smears for cytology were made from lesions on four cats with severe mange. Sera from 21 cats and the dog were analysed for specific antibodies to Sarcoptes scabiei . Molecular characterizations of six individual mites were done. Large numbers of S. scabiei were isolated from the infected skin of most of the cats. Two-thirds of the cats showed skin lesions compatible with chronic sarcoptic mange. Macroscopically, internal organs exhibited no obvious pathology. Yeast organisms and coccoid bacteria were found in the smears; penicillinase-negative Staphylococcus aureus was isolated from all samples and Malassezia pachydermatis was identified from four cats. Sarcoptes scabiei was seen histologically in all cats showing chronic skin lesions. No other ectoparasites were found. All analysed cats had specific antibodies against S. scabiei . Twenty-one cats tested negatively for FeLV and FIV. The mites had DNA sequences identical to S. scabiei from naturally infected dogs and Swedish wildlife.
Funding: Self-funded.     

Surveillance of healthy cats and cats with inflammatory skin disease for colonization of the skin by methicillin-resistant coagulase-positive staphylococci and Staphylococcus schleiferi ssp. schleiferi

In this study, bacterial cultures were collected from five sites on each of 50 healthy cats and 48 cats with inflammatory skin disease (ISD), to determine prevalence of carriage and relative frequency of methicillin resistance in coagulase-positive staphylococci and Staphylococcus schleiferi ssp. schleiferi. Latex agglutination testing for penicillin-binding protein 2a (PBP2a) and pulsed field gel electrophoresis (PFGE) were performed on all methicillin-resistant (MR) isolates. Polymerase chain reaction (PCR) for the mecA gene was performed on MR S. intermedius and S. schleiferi isolates. Staphylococcal chromosomal cassette (SCCmec) typing was performed on all MR S. aureus isolates. Coagulase-positive staphylococci and S. schleiferi ssp. schleiferi were isolated from 24 of 48 cats with ISD: Staphylococcus aureus (14 of 24, 58%), Staphylococcus intermedius (11 of 24, 46%), Staphylococcus schleiferi ssp. schleiferi (1 of 24, 4%), and Staphylococcus hyicus (1 of 24, 4%). Prevalence of MR was 7% for S. aureus, 0% for S. intermedius, 100% for S. schleiferi ssp. schleiferi, and 0% for S. hyicus. Coagulase-positive staphylococci were isolated from 17 of 50 healthy cats: S. aureus (10 of 17, 59%), S. intermedius (11 of 17, 65%), and S. schleiferi ssp. coagulans (1 of 17, 6%). Prevalence of MR was 20% for S. aureus, 18% for S. intermedius, and 0% for S. schleiferi ssp. coagulans. All MR isolates were positive for PBP2a via latex agglutination. Methicillin-resistant S. intermedius and S. schleiferi ssp. schleiferi isolates were also positive for the mecA gene via PCR. Methicillin-resistant S. aureus isolates were identified as SCCmec type II. Results of PFGE indicated heterogeneity among isolates. There was no significant difference in staphylococcal isolation or methicillin resistance between study groups. While present, MR coagulase-positive staphylococci are significantly less common in these study populations.     

Pasteurella haemolytica leukotoxin: chemiluminescent responses of peripheral blood leukocytes from several different mammalian species to leukotoxin- and opsonin-treated living and killed Pasteurella haemolytica and Staphylococcus aureus

A luminol-dependent chemiluminescence (LDCL) assay was used to assess the response of polymorphonuclear leukocyte (PMN) preparations from 4 species of ruminants (ie, cattle, sheep, goats, and antelopes) and 6 species of nonruminants (ie, swine, dogs, cats, rabbits, horses, and persons) to both opsonized and nonopsonized preparations of living and heat-killed Pasteurella haemolytica and Staphylococcus aureus and to opsonized and nonopsonized heat-killed strains of each bacterium in the presence of sterile culture supernatant (leukotoxin) from P haemolytica. The LDCL responses of PMN preparations from each of the species studied were greater for living than for heat-killed S aureus. The most efficient LDCL emission was observed with reaction mixtures containing opsonized living S aureus. Regardless whether they contained killed or living bacteria, the opsonized S aureus preparations elicited LDCL emissions more efficiently than did the corresponding nonopsonized preparations. Living P haemolytica cells and their sterile culture supernatant inhibited the LDCL emissions of phagocytically stimulated PMN preparations from ruminants, but not those from nonruminants. The LDCL response of ruminant PMN to nonopsonized living P haemolytica was characterized by the development of a peak response at 10 minutes of incubation followed by a precipitous decrease and a subsequent complete cessation of chemiluminescence. The peak LDCL response was higher for opsonized living P haemolytica than for nonopsonized living bacteria, and the increased response lasted longer. However, opsonization of living P haemolytica with the serum samples tested only temporarily spared the ruminant PMN preparations from the detrimental effects of leukotoxin.(ABSTRACT TRUNCATED AT 250 WORDS)     

Occurrence of staphylococcal species in clinically healthy domestic animals

The incidence of staphylococcus species in healthy animals was investigated in young and adult individuals of cattle, in pigs and in domestic fowl, using the method of selective isolation of strains. A total of 6066 samples was examined; 4567 strains were revealed and they included all known species, except Staphylococcus caseolyticus, S. saccharolyticus, S. schleiferi and S. lugdunensis. 3.8% of strains failed to be identified with any species. The test samples were taken from slaughtered animals, only in calves intravital smears of tonsils were examined. The species most frequently isolated from the tonsil tissue in adult cattle were as follows: S. aureus (19.9%), S. saprophyticus (12.4%), S. hyicus (8.8%) and S. hominis (8.6%). The following species were isolated from the lung tissue: S. saprophyticus (28.8%), S. cohnii (10.6%) and S. epidermidis (10.2%); from the mammary gland parenchyma these were the species S. saprophyticus (17.4%), S. xylosus (13.1%) and S. epidermidis (10%). In the tonsil tissue of pigs the percent proportions of S. aureus and S. hyicus were 44.5% and 31.8%, respectively; the most frequent species detected from the lungs were S. aureus (20.6%), S. saprophyticus (12.3%), S. hyicus (12.1%) and S. epidermidis (11.5%). In domestic fowl the most frequently occurring species were S. epidermidis (23.7%), S. gallinarum (16.5%) and S. aureus (15.4%). In calves the incidence of S. xylosus (37%), S. saprophyticus (19.2%) and S. cohnii (15.2%) was found to be highest. The indicence of the other staphylococcus species in all test animals can be expressed by low percentages.     

Reinfection of bovine mammary glands following dry-cow antibiotic therapy

Dry-cow antibiotic therapy (DCT) was administered to quarters with Staphylococcus aureus or streptococcal infections and the quarters were closely monitored for the presence of new or reactivated mammary infections throughout the dry period and the following lactation. Strains of S. aureus were characterized using a selection of biotyping tests to allow a comparison of S. aureus strains isolated before and after DCT. Cows with 3-4 quarters infected prior to DCT had a high susceptibility to reinfection in the following year. In contrast, for cows with 1-2 quarters infected prior to DCT and for heifers with no previous history of infection, the susceptibility to reinfection or new infection was very low. The majority of the S. aureus infections appearing in the lactation following DCT were due to S. aureus strains which differed from strains isolated prior to DCT, suggesting that these were new infections. Histopathological examination of quarters which had had recurrent S. aureus infections revealed lesions typical of chronic S. aureus mastitis, including extensive lobular fibrosis and atrophy.