STUDIES IN URINARY TRACT INFECTIONS

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.

Taxonomy of coagulase-negative staphylococci: a comparison of two widely used classification schemes

In a comparative study 351 strains of Micrococcus subgroups 1-3 (Baird-Parker, 1963, 1965, 1974) were classified according to the Kloos and Schleifer scheme (1975b). The results showed that Micrococcus subgroups 1, 2 and 3 are heterogeneous groups in the Kloos and Schleifer scheme. Strains belonging to Micrococcus subgroups 1 and 2 were mostly classified by the Kloos and Schleifer criteria as Staphylococcus hominis, Micrococcus subgroup 3 strains from the skin as S. cohnii, while Micrococcus subgroup 3 strains from urinary infections were classified mainly as S. saprophyticus. The correlation of novobiocin resistant S. saprophyticus biotype III (Baird-Parker, 1974) with S. saprophyticus (Kloos and Schleifer, 1975a, 1975b) when isolated from urine, was 80%. Although the Kloos and Schleifer scheme provides more information about biochemical characters, doubts are expressed about the validity of some of the species so delineated.

The identification of staphylococci in clinical and food microbiology laboratories

A comprehensive review of the methods which have been utilized for the identification of staphylococci is presented. Biochemical characteristics which have assisted in the primary isolation of staphylococci, such as pigmentation, hemolytic activity, the egg yolk phenomenon, and deoxyribonuclease and coagulase production, are also analyzed. The potential applicability of advanced techniques to identify staphylococci, such as the detection of enterotoxin production, base ratio analysis, cell wall analysis, phage typing, and serology, is discussed. The following procedures are recommended for routine use: Idnetification of Staphylococcus sp. (clinical laboratories): microscopic observation, catalase activity, coagulase production, lysostaphin sensitivity, and (optional) facultative growth in thioglycolate medium. Identification of Staphylococcus aureus (food laboratories): microscopic observation, catalase activity, coagulase production, thermonuclease production, and (optional) lysostaphin sensitivity.

Some properties of coagulase-negative deoxyribonuclease-producing strains of staphylococci from human infections

Twenty-seven coagulase-negative and deoxyribonuclease-positive staphylococci were isolated from more than 3000 specimens from human infections. The strains were tested by conventional biochemical tests and by simple agar plate assays for production of different extracellular enzymes and toxins. Three strains were lysed by S. epidermidis phages and 7 strains by S. aureus phages. All strains produced thermolabile nuclease but only 21 strains produced thermostable nuclease. The investigated strains belonged to a heterogeneous intermediate group sharing characters of S. aureus and S. epidermidis. Tests for production of coagulase and thermostable nuclease should be used in the classification of these intermediate strains in diagnostic bacteriology.

Gram-positive, motile, cluster-forming cocci as a cause of urinary infection

One hundred and thirteen strains of motile, Gram-positive, catalase-positive, cluster-forming cocci were isolated from patients with urinary infection attending a private surgery. They constituted 1% of the total 11 302 positive cultures. The biochemical characteristics and the drug sensitivities of the strains are described. The significance of motility for organisms which cause urinary infections is pointed out.At the present time the organisms isolated are orphans in the controversial classification of staphylococci and micrococci.