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The authors investigated 352 strains of coagulase-negative staphylococci isolated from hemo-cultures of patients with assumed bacteraemia who were hospitalized in standard hospital departments and intensive care units. The strains were identified using STAPHYtest 16 and 14 different species and subspecies of coagulase-negative staphylococci were found. Most frequent were strains of Staphylococcus epidermidis (53%), strains of S. hominis subsp. hominis (22%) and S. haemolyticus (13%). In the strains the production of slime and delta-haemolysin was investigated. The formation of these two important factors of virulence was recorded in 95% strains (incl. major slime production in 13.4%), and 50% strains resp. The resistance to 13 antibiotics was also assessed. A total of 91% strains were resistant to penicillin, 63% to oxacillin and amoxicillin with clavulanic acid, 67% to gentamicin and 66% to erythromycin. In the group 15 strains of a recently described subspecies S. hominis subsp. novobiosepticus was identified. These isolates displayed most frequently resistance: they were resistant in 100% to five antibiotics (penicillin, oxacillin, erythromycin, clindamycin and amoxicillin with clavulanic acid) and with a single exception to another three antibiotics (chloramphenicol, gentamicin and ciprofloxacin). In these strains most frequently slime as well as delta-haemolysin was found. The authors assume, consistent with previous work, that it is important to focus attention on the incidence of strains of S. hominis subsp. novobiosepticus which very probably play an important role as agents in hospital infections. The authors describe also detection of one strain of S. cohnii subsp. urealyticum which was resistant to 10 of 13 antibiotics. The authors are convinced that also classical phenotypic analysis can contribute in an effective manner to the solution of the problem of infections caused by coagulase-negative staphylococci.

In the National reference laboratory for staphylococci in the National Institute of Public Health in Prague a new dichotomic schema ORIDES was elaborated for the preliminary identification of 17 species of coagulase-negative staphylococci which can be isolated from human clinical material. Tests of 986 strains revealed that ORIDES can serve rapid and cheap assessment of these bacteria, the importance of which is increasing.

Reliable laboratory diagnosis of coagulase-negative staphylococci and subsequent assessment of the MIC of these strains is part of the essential routine work of clinical laboratories with regard to the rising incidence of nosocomial coagulase-negative staphylococci infections, in particular in specialized departments concerned with important clinical issues.

In the series of 212 coagulase-negative staphylococci strains isolated from blood cultures, in which the slime production was tested by means of two methods--a method using agar with Congo red and a Christensen method--S. epidermidis, S. haemolyticus and S. hominis were identified most frequently (in 69.3%, 18.4% and 6.6%, respectively). The slime production was detected by both methods in 28 strains (13%) of four species, most often in S. epidermidis (in 17%). By comparing the Congo red agar method with the Christensen method the sensitivity and specificity of the former was determined (85% and 99%, respectively). Thus the Congo red agar method for the detection of slime production by staphylococci seems to be a reliable tool.

A simplified scheme for the subdivision of coagulase-positive staphylococci and another simplified scheme for the diagnostics of coagulase-negative species were worked out. On the basis of the production of staphylokinase, coagulation of human and bovine plasma, acetoin production from glucose, and growth on agar with crystal violet, it is possible to identify S. aureus with its biovars A, B, C1, C2, D, as well as S. intermedius. The coagulase-negative species can be diagnosed according to their sensitivity to novobiocin, nitrate reduction, fermentation of maltose, sucrose, salicin, xylose, trehalose, mannitol and mannose, and haemolytic activity. The proposed diagnostic schemes were verified with success on the collection strains and on the 1305 staphylococci strains isolated largely from the bovine mammary gland, from dogs, man and domestic fowl. In S. aureus strains a close correlation was demonstrated between their biotype characteristics and the host species. A similar correlation was determined for S. intermedius. As to the coagulase-negative species, S. epidermidis, S. hominis and S. haemolyticus were diagnosed most frequently. Both schemes represent a reliable, prompt and technically simple method of the diagnostics of the Staphylococcus microorganisms.

Using the Streptococcus equi decapsulation test, 879 strains of S. aureus, 212 strains of S. intermedius and 214 coagulase-negative staphylococci were examined for hyaluronidase production; six of the coagulase-negative staphylococci belonged to S. hyicus subsp. hyicus. Positive hyaluronidase production was recorded in all strains of S. aureus and in the strains of S. hyicus subsp. hyicus. No hyaluronidase was produced by 208 coagulase-negative staphylococci and the strains of S. intermedius. The decapsulation test is recommended as a reliable method of the differentiation of S. aureus and S. intermedius.