[Micrococcus luteus: a rare pathogen of valve prosthesis endocarditis]

A rare case of prosthetic valve endocarditis caused by Micrococcus luteus is described and compared with the few cases reported in the literature, as well as the clinical features, microbiological profile, therapy, and prognosis of common prosthetic valve endocarditis. Micrococcus luteus is a constituent of the normal human buccal bacterial flora which forms yellowish colonies and appears as a gram-positive coccus typically arranged in tetrades. Although of low virulence, the germ may become pathogenic in patients with impaired resistance, colonizing the surface of heart valves. In contrast to staphylococci (for which it may easily be mistaken) it is usually penicillin-sensitive. However, the most promising antibiotic regimen proposed for treatment of Micrococcus luteus seems to be a combination of vancomycin, amikacin, and rifampicin. If the infection leads to severe hemodynamic alterations, however, valve replacement may become necessary similar to the situation in prosthetic valve endocarditis caused by more aggressive and highly resistant bacteria.

Effects of Corynebacterium bovis infection on susceptibility to major mastitis pathogens

Experimental challenge procedures were used to study infectivity and virulence of Corynebacterium bovis. Challenge procedures using Staphylococcus aureus (Newbould 305) and Streptococcus agalactiae (McDonald 44) were used to study effects of Corynebacterium bovis infections on superinfection with major pathogens. Rate of infection under experimental challenge conditions was significantly greater with Corynebacterium bovis than previously observed for Staphylococcus aureus or Streptococcus agalactiae. Principal location of Corynebacterium bovis colonization appeared to the teat canal region, although the organism was isolated from 75% of the teat cisterns by puncture technique. Quarters with Corynebacterium bovis infections were more resistant to infection by Staphylococcus aureus than bacteriologically negative quarters. Quarters infected with Corynebacterium bacterium bovis were approximately 8.5-fold more susceptible to Streptococcus agalactiae infection than negative quarters. Somatic cell counts were doubled in negative quarters that developed Corynebacterium bovis infections; the geometric mean was 2.4 X 10(5).

Role of coagulase-negative staphylococci and micrococci in ocular disease

Forty-nine strains of coagulase-negative staphylococci and 26 strains of micrococci isolated from human eyes were classified by the Baird-Parker system of 1966. The staphylococci belonged to subgroups II, III, IV, and V with one strain each in subgroups III and IV. However, when biotyped by Baird-Parker's system of 1974, less than 50% (23/49) of strains were typable and they belonged to biotypes 1 and 2. With our proposed modified classification all strains could be classified into biotypes 1, 2, and 3. All the 26 strains of micrococci belonged to subgroup VII. Staphylococci isolated from diverse sources produced, qualitatively and quantitatively, different corneal pathology in rabbits when compared to those isolated from healthy conjunctiva. This bore no relation to the present system of subtyping based on biochemical reactions. Micrococci were incapable of producing experimental corneal lesions in the rabbit.

Micrococcus indolicus. Some biochemical properties, and the demonstration of sex antigenically different types

A total of 274 strains of Micrococcus indolicus, 211 of which had been isolated from cases of summermastitis, 13 from other cases of mastitis in cattle, 15 from other suppurative lesions in cattle, 13 from insects, 13 from the vagina and interdigital skin of clinically healthy cows, and 9 from various suppurative lesions in swine, were studied and compared with 4 strains of anaerobic cocci of human origin, presumably representing at least 3 species closely related to Mi. indolicus: Staph. asaccharolyticus Distaso, Staph. aerogenes Schotmüller, and Staph. anaerobius Jungano.

The growth characteristics of Mi. indolicus are described, and the most important biochemical criteria for its identification stated briefly (Table 1).

By double diffusion-in-gel analysis 217 strains of Mi. indolicus could be divided in 6 antigenic types, designated A, B, C, D, E, and F (Figures 2, 3, 4, and 5, Tables 2, 3, 4, and 6).

By the complement fixation technique no difference could be demonstrated between the 6 types (Table 5).

Strains isolated from healthy cattle or from insects all belonged to antigenic types commonly found in summermastitis.

Three of 9 porcine strains belonged to a type (F) hitherto not found in cattle.

The 4 human strains of anaerobic cocci showed no antigenic relation to Mi. indolicus (Table 5) and differed from it in growth characteristics and in biochemical properties (Table 1).

It is concluded that, as suggested by Christiansen (1934) Micrococcus indolicus should be classified as a species of its own and not as a variant of Staphylococcus asaccharolyticus Distaso (Prévot et al. 1967).

Effects of Gaffkya homari on glucose, total carbohydrates, and lactic acid of the hemolymph of the lobster (Homarus americanus)

The lobster pathogen, Gaffkya homari, in vitro and in vivo caused the virtual disappearance of glucose and lactic acid from the hemolymph of the lobster, Homarus americanus. In vitro results suggested that almost half of the non-glucose components of the hemolymph could be used by G. homari.

Association of toxic capsule and cell wall mucopeptide with virulence in Gaffkya tetragena

Nine strains of organisms morphologically and physiologically identified as Gaffkya tetragena were obtained from various sources to study their pathogenicity. Initial virulence analysis of all strains by mouse intraperitoneal injection of viable cells revealed that only three strains, recently isolated from and associated with respiratory infections in hospitalized patients, caused death of mice within 48 hr. The ld(50) for these virulent, encapsulated strains was 1 x 10(7) to 6 x 10(7) viable organisms. To associate virulence with a toxic component, the following fractions were purified from all strains: capsular material, cell walls, mucopeptide preparations from cell walls and whole cells, grouplike material, cytoplasmic material, and culture filtrate with and without added reducing agent. Rabbit and mouse dermal toxicity testing of these fractions revealed that the capsular material, cell walls, and mucopeptide preparations of the virulent strains were toxic. None of the nonvirulent strains contained toxic components, with the exception of one strain which yielded capsular material equal in toxicity to that of the virulent strains. The capsular material induced a soft pustular lesion persisting for approximately 22 days. Cell walls and mucopeptide preparations produced a hard nodular lesion, identical to that produced by autoclaved whole cells, that persisted for 25 to 30 days. One strain may represent a virulence intermediate between the virulent and nonvirulent strains, since it contains toxic capsular material but nontoxic cell wall mucopeptide. The results indicate that the virulence of this organism is associated with toxic capsular material and cell wall mucopeptide.

Subcutaneous staphylococcal infection in mice. II. The inflammatory response to different strains of staphylococci and micrococci

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