Bacteriophage typing of canine staphylococci. I. Typing by use of the International Phage Sets for human and bovine staphylococci.
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Phage heterogeneity of coagulase-negative staphylococci isolated in the United States and Sweden from bovine milk.
A Swedish bovine and a Dutch human phage set for coagulase-negative staphylococci were used to phage type coagulase-negative staphylococci isolated from bovine milk from Minnesota dairy herds. A comparison was also made of the deoxyribonuclease activity of coagulase-negative staphylococci isolated from bovine milk in Sweden and Minnesota. Of 133 Minnesota isolates, only one could be typed with the Swedish set and one by the Dutch set, whereas of 218 Swedish strains, 49 could be typed with the Swedish set and 7 by the Dutch set. A larger number of coagulase-negative isolates from Sweden were deoxyribonuclease positive (35%) than were the similar isolates from Minnesota (12%). These findings substantiate the marked heterogeneity of coagulase-negative staphylococci isolated from bovine udders. Results presented point to the usefulness of establishing regional phage sets for epidemiological investigations of coagulase-negative staphylococci in cattle. It is anticipated that at a later stage the regional phage sets will be coordinated internationally.
Animals↗
Staphylococcus aureus-strains of phage group II and their possible relation to animal staphylococci. 1. Antigenic properties, phage typing, and resistance to antibiotics.
Investigations carried out on 350 strains isolated from clinical materials and carriers revealed that among coagulase-positive staphylococci of phage group II two main serologic types predominated. The first (61,1%) was characterised by positive reaction with factor serum 263-2, the second (30,8%) one gave positive reaction with factor serum i1-2. The strains of type 263-2 contained as a rule polysaccharide A as well as polysaccharide 263, contrary to staphylococci belonging to type i1-2 which possessed polysaccharide A only. Both serologic types differed also epidemiologically, in phage typing and resistance to antibiotics. Staphylococci of serologic type 263-2 occurred in neraly all purulent lesions, they were more resistant to antibiotics than type i1-2 and prevailed in hospital environments. In phage-typing the differences between both serologic types were quantitative in character, with two being most outstanding, namely the prevalence of strains sensitive to phage 71 among staphylococci of serologic type 263-2 and of phage types 3A, and 3C as well as 3A, 3B, 3C among staphylococci of serologic type i1-2. There was no correlation between the susceptibility of strains to phage 71 and their virulence, the latter seemed to be connected with serologic type.
Anti-Bacterial Agents↗
Establishment of a new bacteriophage set for typing avian staphylococci.
A new phage set was proposed for the typing of coagulase-positive staphylococci from chickens. The set was composed of 16 phages isolated from lysogenic staphylococci from chickens and 3 adapted phages derived from the international phage set. These phages were classified into 4 groups (I, II, III and IV) according to their host ranges. The 19 phages were used for typing 569 coagulase-positive staphylococci; 94.2% of the isolates were lysed by 1 or more phages, 88.0% at a routine test dilution, and 6.25% only at a routine test dilution X 100. The reacting ability of the phages seemed to be limited to staphylococci from chickens. It was proved that the phages were more accurate than the international phage set in typing staphylococci isolated from chicken in Japan.
Animals↗
Phage typing of coagulase-negative staphylococci.
218 bovine and 116 human strains of coagulase-negative staphylococci and 46 bovine Staphylococcus aureus strains were typed with the Verhoef-phage set for human staphylococci and the Holmberg-set for bovine staphylococci. 22.5% of the bovine strains were lysed by the bovine phages and only 3.2% by the human phages. None of the bovine Staph. aureus strains could be typed. 21% of the human strains tested were lysed by the human phages and only 5.2% by the bovine phages. These results clearly demonstrate the need of separate phage sets for the typing of bovine and human coagulase-negative staphylococci.
Animals↗
[Electron microscopic investigations on encapsulated Staphylococci (author's transl)].
Attempts were made to study the surface of encapsulated staphylococci by electron microscopy. After fixation with osmium tetroxide the encapsulated staphylococci showed a "hazy" cell-surface, possibly because of capsular components (Fig. 1). On the other hand, the nonencapsulated staphylococci exposed a "smooth" surface of the cell wall (Fig 1). Similar findings were obtained after the immuneferritintechnique (Fig 2). The staphylococcal capsules could be clearly demonstrated by the "negative contrasting" method with ferritin (Fig 3). The capsules did not significantly enlarge after reaction of the encapsulated staphylococci with their homologous antiserum.
Ferritins↗
Relatedness among coagulase-negative staphylococci: deoxyribonucleic acid reassociation and comparative immunological studies.
DNA-DNA-homology values were determined under restrictive to relaxed reassociation conditions with type strains and some additional strains of coagulase-negative staphylococci belonging to ten different species. The immunological relationship of the catalases present in the type strains of these species was also determined by applying double immunodiffusion and microcomplement fixation. The results of these studies support the previous proposal to subdivide the coagulase-negative staphylococci into at least ten separate species. However, it is evident that some of the species are more closely realted than others and can form species groups. According to the results presented in this study, the coagulase-negative staphylococci can be combined into five species groups: The Staphylococcus saprophyticus group is composed of S. saprophyticus, S. xylosus and S. cohnii. The S. epidermidis group comprises S. epidermis, S. capitis and S. warneri. The S. hominis group which exhibits a significant relationship to S. epidermidis includes S. hominis and S. haemolyticus. The species group S. sciuri consists of S. sciuri ssp. sciuri and S. sciuri ssp. lentus and the species group S. simulans is presently represented by the corresponding single species.
Catalase↗
Genomic diversity and resistance determinants of staphylococci from cow and buffalo milk.
BACKGROUND: Staphylococci are important mastitis pathogens in dairy animals and serve as reservoirs of antimicrobial resistance genes (ARGs) having zoonotic potential. Genomic characterization of resistant isolates is essential to understand their diversity, resistance mechanisms, and One Health implications. METHODS AND RESULTS: A total of 363 cow and buffalo milk samples-including 108 from animals with mastitis-were screened, yielding 98 staphylococcal isolates, comprising 20 Staphylococcus aureus and 78 coagulase-negative staphylococci (CoNS). Antimicrobial susceptibility testing revealed resistance to cefoxitin (CoNS: 21.7%; S. aureus: 10%), tetracycline (CoNS: 19.2%; S. aureus: 10%), erythromycin (CoNS:16.7%; S. aureus: 10%), gentamicin (CoNS: 10.2%; S. aureus: 10%) and fluoroquinolone (CoNS: 10.2%), while the majority were sensitive to chloramphenicol, cotrimoxazole (~ 95%, each), linezolid (~ 97%), and vancomycin (100%). Nineteen isolates, including two S. aureus, were cefoxitin-resistant, and eight carried the mecA gene. Whole genome sequencing of these eight isolates revealed genome sizes ranging from 2.27 to 2.78 MB, with the methicillin resistant S. aureus (MRSA, ERSST98) isolate possessing the largest genome and the highest rRNA copy number. Comparative genomic analysis revealed various SCCmec types along with an extensive array of resistance determinants, encompassing aminoglycosides, macrolides, tetracyclines, efflux systems, and heavy metals, underscoring the multifaceted resistance repertoire of these strains. Virulence profiling of ERSST98 demonstrated a broad arsenal of adhesins, toxins, and biofilm‑associated genes, highlighting its pathogenic capacity. Mobile genetic elements with diverse plasmid replicons and insertion sequence families further contributed to genomic plasticity. CONCLUSIONS: Collectively, this study underscores the genomic diversity of methicillin-resistant staphylococci from dairy animals with extensive resistance determinants and highlights their zoonotic relevance within One Health framework.
Animals↗
Classification of coagulase-negative staphylococci in the diagnostic laboratory.
One hundred and ninety-eight coagulase-negative staphylococci isolated from urines, blood cultures, and pus samples were classified by means of two identification schemes, and their wall teichoic acids were determined serologically. S. epidermidis, S. saprophyticus, and S. cohnii were identified reliably by the use of five criteria: acid aerobically from sucrose, trehalose, and mannitol, phosphatase production, and sensitivity to novobiocin. Further species, notably S. haemolyticus and S. hominis, could be identified when haemolysis on blood agar plates was included in the criteria group. The investigation shows, that a considerable number of coagulase-negative staphylococci isolated from human specimens belong to species other than S. epidermidis and S. saprophyticus. These staphylococci can cause human infections and should be identified in the diagnostic laboratory. S. epidermidis and S. saprophyticus were found to contain the teichoic acids previously identified in these species. S. cohnii contained the same teichoic acids as S. saprophyticus. No characteristic teichoic acid was demonstrated in the other species, but several strains contained poly C (beta-N-acetylglucosaminylglycerol teichoic acid).
Bacteriological Techniques↗
On the diagnosis of coagulase-negative staphylococci with emphasis on Staphylococcus saprophyticus.
This study concerns the diagnosis of coagulase-negative staphylococci, with special emphasis on novobiocin-resistant species, vis S. saprophyticus, S. cohnii and S. xylosus. Disc diffusion tests for novobiocin were found useful in the differential diagnosis of coagulase-negative staphylococci isolated from urine specimens, but not from pus and blood cultures. We report on the resistance of S. saprophyticus to nalidixic acid and the use of this characteristic in the diagnosis of coagulase-negative staphylococci known to be novobiocin-sensitive, but which have subsequently acquired resistance to novobiocin. The results of different tests for betalactamase production in S. saprophyticus are presented. "Clover leaf" tests suggested such a production in about half of the strains studied, while no strain produced betalactamase as indicated by tests using chromogenic cephalosporin or benzylpenicillin in capillary tube tests. -The failure of tests for nitrate reduction, glucose consumption and of cultrues of urine on MacConkey's agar in the diagnosis of urinary tract infections caused by S. saprophyticus, is documented. The concept "significant bacteriuria" in the diagnosis of S. saprophyticus infections of the urinary tract above the bladder neck is also considered.
Bacteriological Techniques↗
Species identification of coagulase-negative staphylococci from urinary tract isolates.
A new scheme for identification of coagulase-negative staphylococci was applied to 138 consecutive urinary isolates of coagulase-negative staphylococci. The most common species were Staphylococcus epidermidis (53%), S. hominis (12%), and S. haemolyticus (10%). S. saprophyticus comprised only 5%. The disk method for antibiotic susceptibility for all species grouped together disclosed resistance most commonly to penicillin (35%), tetracycline (33%), methicillin (27%), and sulfonamide (24%). This pattern was also seen specifically with S. epidermidis. Further studies are needed to determine the incidence of species-specific antibiotic resistance and species-specific infection by site. This may be of particular interest in those patients with nosocomial infections due to coagulase-negative staphylococci.
Anti-Bacterial Agents↗
Pseudocoagulase activity of staphylococci.
A total of 245 strains of staphylococci isolated from various pathological specimens derived from cases of human infections was tested for staphylocoagulase activity. Test systems employing normal citrated rabbit plasma and the same substrate supplemented with inhibitors of thrombin and proteolytic enzymes (but not influencing the staphylocoagulase activity) were used for testing suspensions of bacteria and cell-free culture supernatants. A total of 237 strains clotted normal rabbit plasma; however, addition of Trasylol and heparin resulted in positive results in 222 strains, whereas plasma supplemented with Trasylol and hirudin was coagulated definitely by only 173 strains. It is postulated that proteolytic enzymes of staphylococci interfere with staphylocoagulase-induced clotting and may simulate coagulase-positive activity of staphylococci. To avoid such false results, a test system for detection of staphylocoagulase should include proteolytic enzyme inhibitors. Possible mechanisms of these findings are discussed.
Animals↗
Isolation and characteristics of bacteriophages from staphylococci of chicken origin.
Lysogenicity in chicken coagulase-positive staphylococci was tested by incubating the strains in the presence of mitomycin C. Of 88 strains tested, 84 (95.5%) were proved to be phage carriers and 81 were susceptible to any of the phages. The lysogenic strains were detected with almost equal frequency from both of typeable and untypeable strains by the international phages. Sixteen phages (CH phages) were isolated from chicken lysogenic strains, and their usefulness for the typing of chicken staphylococci was evaluated. Of 122 strains examined, 101 (82.8%) were found to be typeable with the CH phages at a routine test dilution (RTD). About 82% of strains untypeable by the phages of the international series were lysed by one or more of the CH phages. The phages seemed to be highly specific to chicken staphylococci, because they lysed only a few strains of animal origin other than chicken. Thus, the 16 phages newly established were found to have significant advantages in typing chicken strains.
Animals↗
A comparative immunological study of catalases from coagulase-positive staphylococci.
Protein homology studies with catalase as a reference point were carried out with coagulase-positive staphylococci belonging to Staphylococcus aureus, S. intermedius and S. hyicus. Antisera against catalases of S. aureus ATCC 12600 and S. aureus ATCC12601 reacted very weakly employing double immunodiffusion and quantitative microcomplement-fixation assay with cell-free extracts or catalase enriched preparations of S. intermedius or S. hyicus. The differences between coagulase-positive staphylococci could be confirmed by using the antiserum against S. intermedius H 11 catalase. Within the strains of the species S. intermedius immunological distances ranging up to 25 indicate a heterogeneity which justify the separation of the biotypes E and F on a subspecies level. Coagulase-positive strains of S. hyicus revealed neither a close relationship to S. aureus nor to S. intermedius.
Animals↗
Effect of DDT and gamma-HCH on the biological properties of staphylococci.
The effect of DDT and gamma-HCH in concentrations of 100, 50, and 10 micrograms on the biological properties of staphylococci was studied. Both substances proved to be inhibitory to coagulation of rabbit plasma and to penicillinase production, causing depigmentation of the colonies. The morphological structure of cells is affected by these substances as well. The growth of the strain is not substantially influenced. Gas chromatography proved that staphylococci do not participate in the DDT and gamma-HCH degradation in the medium.
Animals↗
Dichotomy between opsonization and serum complement activation by encapsulated staphylococci.
Previous studies have demonstrated that encapsulated Staphylococcus aureus strains are not effectively opsonized by the serum complement system. Encapsulated staphylococci thereby "resist phagocytosis." To test whether this phenomenon might be explained by an inability of encapsulated strains to activate complement, the relationship between staphylococcal opsonization and serum complement activation was studied. Although encapsulation was found to interfere with opsonization by pooled human serum (human polymorphonuclear leukocytes phagocytized significantly fewer encapsulated bacteria than unencapsulated bacteria after incubation in this opsonic source), encapsulated (S. aureus M and Smith diffuse) and unencapsulated (S. aureus M variant and Smith compact) strains had similar capacities for complement activation as measured by C3-C9 consumption. When C2-deficient and immunoglobulin-deficient sera were studied, again C3-C9 consumption was not influenced by the presence or absence of a capsule. In addition, C3 was detected on the surface of both S. aureus M and M variant strains after incubation in pooled serum and staining with fluorescein-conjugated anti-C3 antibody. Thus, encapsulated staphylococci are not effectively opsonized even though complement is activated and C3 is present on the bacterial surface. The exact mechanism by which the capsule interferes with opsonization is still not known; however, inhibition of complement activation appears not to be the explanation of this phenomenon.
Antibodies↗
Detection of Haemophilus influenzae type b antigens in body fluids, using specific antibody-coated staphylococci.
Protein A-rich staphylococci coated with Haemophilus influenzae type b antiserum agglutinate specifically with homologous bacterial cells or with cell-free supernatant fluids of cultures of the organism. Antibody-coated staphylococci were used to detect soluble antigens in body fluids of patients infected with H. influenzae type b. Cerebrospinal fluid from 36 cases of meningitis caused by this orgainsm showed positive coagglutination tests in 86% of patients prior to initiation of therapy. Antigens could be detected in 46% of sterile cerebrospinal fluid specimens obtained from the same cases 1 to 10 days after therapy. Soluble antigens were also detectable in sera (58%) and urine specimens (67%) of patients with H. influenzae type b septicemia, when such specimens were tested within 10 days of onset of illness. No antigen could be detected in body fluids beyond 10 days. The coagglutination test was positive in 57% of all body fluids examined; contercurrent immunoelectrophoresis (CCIE) was positive in only 27%. All specimens positive by CCIE were also positive by coagglutination. No false-positive reactions were noted by either test in body fluids from controls. The coagglutination test is simple, specific, and more sensitive than the CCIE method and could be a valuable tool for detecting antigens in body fluids of patients with various infections.
Agglutination Tests↗
Efficacy of direct Gram stain in differentiating staphylococci from streptococci in blood cultures positive for gram-positive cocci.
A preponderance of clusters seen on direct Gram stain of blood cultures positive for gram-positive cocci was 98% sensitive and 100% specific for identification of staphylococcal species or of Peptococcus. A preponderance of chains, pairs, or both was 100% sensitive and 98% specific for identifying streptococci. Further presumptive identification of either staphylococci or streptococci based on microscopic morphology was unreliable. The direct Gram stain is highly reliable for differentiating staphylococci from streptococci and should be of considerable value to clinicians selecting initial antimicrobial therapy.
Blood↗