Coagulase-negative staphylococci in air samples from operating theatres.

The aim of our study was to recognize coagulase-negative staphylococci (CNS) in the air of operating theatres. Out of the identification of 449 isolates, the most frequent species were Staphylococcus epidermidis and Staphylococcus haemolyticus. The strains were adherent to glass in 52.3%. Most of the S. epidermidis showed adherent growth, while the majority of the S. haemolyticus failed to adhere. The disk-diffusion antibiotic sensitivity tests showed great differences in sensitivity to penicillin, tetracycline and erythromycin between adherence-positive and negative isolates. On the whole, the species S. haemolyticus proved to be much more resistant than S. epidermidis. Staphylococcus warneri was the most, while S. haemolyticus was the least sensitive to phages.

[Immunosuppressive effect of cyclophosphamide in experimental coagulase-negative staphylococcal infection]. / Cyclophosphamid immunszuppresszió hatása experimentális koaguláz-negatív staphylococcus fertözésekre.

BALB/c mice were given 200 mg/kg cyclophosphamide intraperitoneally. Three days later, mice were infected intraperitoneally with Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus saprophyticus at 4 inocula ranging between 2 x and 20 x 10(8) CFU/ml suspended in dextran microcarrier solution. Controls were treated only with bacteria. Lethality rates and organ persistence of cocci were significantly higher, and more peritoneal abscesses and adhesions developed in the mice pretreated with cyclophosphamide than in the untreated controls, regardless of the species of Staphylococcus injected. Splenomegaly was also more pronounced indicating a probably enhanced compensatory reactivity of the immune system liberated from suppression 13 days after the administration of cyclophosphamide. Our results show that cyclophosphamide treatment increases the susceptibility of mice to infection by coagulase-negative staphylococci and it is also responsible for a more severe course of the diseases provoked.

[Pathogenic properties of coagulase-negative staphylococci in experimental infections]. / Koaguláz-negatív staphylococcusok patogenetikai tulajdonságai experimentalis fertözésekben.

The frequency of persistence of three Staphylococcus epidermidis, Staphylococcus haemolyticus and Staphylococcus saprophyticus strains, respectively, was studied in BALB/c mice at the 10th day of intraperitoneal (ip) challenge. 245 out of 416 mice survived after infections with four bacterial suspensions of different colony forming units (CFU) of each strain. Staphylococci persisted in 61 mice (24,9%). The main sites of persistence were the kidneys, while cocci were rarely isolated from the spleen and the liver. S. epidermidis persisted with a significantly higher rate than the other two species, because S. epidermidis in 28,8%, S. haemolyticus in 4,9%, and S. saprophyticus in 3,6% were reisolated from the organs of the respective infected and surviving animals. The organ persistence was proportional to the amount of bacteria injected. The persistence resulted in subacute microabscesses in the organs. Reisolates of persisting bacteria remained stable in phenotype and genotype concerning antibiotic resistance patterns and biochemical activities for the taxonomic implication, whereas cell surface properties characterizable with phage types altered considerably during persistence. It is concluded that cocci of all three Staphylococcus species are invasive and can persist to a certain extent in the organs of animals with normal immune system, too, after artificial inoculation into the peritoneum i. e. to the serosal surfaces.

A comparative study on growth in soft-agar, adherence to glass and haemolysis types of coagulase-negative staphylococci.

Growth properties of coagulase-negative staphylococci in the presence and in the absence of human and rabbit serum in soft-agar prepared in modified Staphylococcus 110 broth were studied. The adherent growth was examined in modified Staphylococcus 110 broth and 1% glucose-meat broth. Of 100 strains examined 69% exhibited diffuse, 18% compact, 7% transient and 6% mixed growth. Compact type colonies were mainly characteristic of Staphylococcus haemolyticus strains. The presence of serum failed to influence the types of colony morphology in any of the strains. Sixty-three percent of the strains showed adherent growth; none of the S. haemolyticus strains produced adherent growth. The glucose-meat broth, unlike modified Staphylococcus 110 broth, was suitable to study adherence. The coincidence of the compact colony morphology in soft-agar and the absence of adherent growth seems to be a taxonomic sign for the species S. haemolyticus and differentiate it from the species Staphylococcus epidermidis.

Clonal distribution of K1 and K5 antigen possessing Escherichia coli isolates.

A significant difference was observed in the occurrence of the examined markers (Col+, ColV+, Hly+, Aer+, AbR) and in the plasmid carrier state between strains with and without K1 and K5 antigens. Plasmids of the same size were harboured by serotypes possessing K1 and K5 antigens, e.g. among O1: K1: H- strains plasmids of 60-79 Md, among O1: K1: H7, O18ac: K1: H7, O45: K1: H7 and O83: K1: H- strains plasmids of 80-95 Md were frequent. The average plasmid number was higher in K1 strains than in K5 strains. In serogroup O1 the frequency of the plasmid carrier state was associated with the O serogroup and not with the K antigen. The plasmid number in K5 of serogroups O6 and O18 was lower than in K5- strains. Plasmids of 80-95 Md were predominant among the strains derived from blood and cerebrospinal fluid, whereas these plasmids were rare among the K1 and K5 strains isolated from other sources. Plasmids of 60-79 Md were frequent among strains derived from different sources. The 30-40 Md plasmids were relatively frequent among strains isolated from urine. In contrast with literary data, O1: K1: H-, O1: K1: H7 and other frequent serotypes consisted of different clones. Different clones were found within a single serotype, too.