Laboratory criteria in the diagnostics of intestinal infections of staphylococcal etiology in children.

Faecal samples were investigated from 948 children hospitalized with the diagnose of acute intestinal infection. The authors studied the isolation and properties of a broad spectrum of microorganisms from children's faeces: Salmonella, Shigella, E. coli, S. aureus, rotaviruses, Klebsiella, Morganella, Proteus. As a result, laboratory criteria were formulated of diagnosing in children intestinal infection of staphylococcal etiology.

Concerning the sensitivity of Acinetobacter calcoaceticus.

The strains of Acinetobacter calcoaceticus, var. anitratus (A. c. a.) were isolated in the nosocomial environment as an opportune pathogen. The therapy of choice may be determined after in vitro tests. Our results show following therapeutical possibilities: beta-lactam antibiotics--cephalosporins of IIIrd generation (cefotaxime), also combinations of antimicrobials have shown good results: amoxycillin or ticarcillin with clavulanic acid. Best synergistic effect was found in combination ticarcillin-amikacin.

Reinfusion of UV-irradiated blood in the treatment of infection. I. Experimental infection with staphylococci.

During the last 10 years, reinfusion of UV-irradiated blood has been rediscovered again as a therapeutic method suitable in the treatment of a variety of diseases. The described series of model experiments on rabbits confirm its beneficial effects in the treatment of staphylococcal infection: the control animals reinfused blood not exposed to UV radiation died all within 48 hours after injected with a suspension of live Staphylococcus aureus culture; all rabbits reinfused UV-irradiated blood (2 ml per kg body weight) survived the whole period of observation (30 days); reinfusion of UV-irradiated blood in a volume reduced to 1 ml.kg-1 body weight prolonged the animals' life-span to 96 or 120 hours.

Drug resistance and pathogenicity of S. aureus isolated from patients.

Over the period 1983-1985, investigators from the Institute of Hygiene and Epidemiology, Prague, and the Central Research Institute of Epidemiology, USSR Ministry of Public Health, Moscow, carried out a joint study of drug resistance in S. aureus strains in relation to their enterotoxigenic properties and phage group specificity. Altogether 277 strains were explored which had been isolated at random from the clinical material from infant and adult inpatients. Most of the isolated strains featured multiple resistance to antibiotics: PNC (77.9%), CMP (52.7%), TET (21.6%), ERY (17.6%) and LIN (11.9%). The strains isolated from infants were most frequently resistant to TET and ERY. No correlation was found between the incidence of antimicrobial drugs resistance and toxigenic properties of the isolated strains.

Experimental investigation of preparations for the immunotherapy of staphylococcal infections.

A comparative experimental study was carried out of antigenic staphylococcal preparations developed in the USSR and Czechoslovakia for the immune therapy of chronic staphylococcal infection. The efficiency of the preparations was unequivocally confirmed using the rabbit staphylococcal sepsis model. The immunogenicity of tested strains was shown not to always correlate with their virulence. Preparations obtained by means of aqueous extraction from mildly virulent immunogenic strains exhibited greater protective activity than those prepared from highly virulent strains. The PCA phenomenon did not differ significantly provided the tested preparations were administered at doses which ensured equal protective action.

Pseudomonas aeruginosa. II. Experimental acellular vaccine of an endotoxin and anatoxin type.

The results are given of quality evaluation of endotoxin and exotoxin antigens isolated from P. aeruginosa strains. The isolates were tested by both in vitro and in vivo methods. The results of an active protection test on white mice formed the basis for the construction of an experimental Pseudomonas vaccine that protects the immunized animals against infection even by heterologous strains of P. aeruginosa.

Electron microscopic study of the effect of gentamicin and oxacillin on Staphylococcus aureus cells: significance of time and sequence of application in combined effect.

The ultrastructure of Staphylococcus aureus cells was studied after their treatment with gentamicin and oxacillin, each used alone or in a simultaneous or successive combination. Gentamicin (concentrations 1 or 2 micrograms/ml, incubation time 1-24 h) did not produce any ultrastructural changes in staphylococcus cells. Oxacillin in the same concentrations caused derangement of cell division accompanied by an increase in cross-wall and decrease of peripheral cell wall thicknesses. Simultaneous incubation of staphylococcus cells with gentamicin and oxacillin (both 1 microgram/ml) led to morphological changes corresponding to those induced by oxacillin. On the other hand, successive incubation with oxacillin (2-5 h), followed by gentamicin (5-24 h) caused complete destruction of staphylococci. This effect was not observed when cells were first incubated with gentamicin and then oxacillin. The study shows the importance of time and sequence factors in the combined effect of tested antimicrobials.

Comparison of effectiveness of aminoglycosides and cephalosporins in gram-negative rods.

Aminoglycosides and cephalosporins belong among antimicrobials with a pronounced effect on most gram-negative rods. In vitro susceptibility and resistance to gentamicin, tobramycin, amikacin, netilmicin, cefoxitin, cefotaxime, cefsulodin, cefoperazone in Klebsiella pneumoniae, Enterobacter spp., Proteus mirabilis, Escherichia coli and Pseudomonas aeruginosa was tested by the quantitative dilution micromethod. Selected, highly susceptible strains of the above species were furthermore compared for minimal inhibitory concentration (MBC) and minimal bactericidal concentration (MBC) values. Aminoglycosides tended to be the most effective drugs for susceptible strains. In view of their relative toxicity possibly optimal combinations of individual aminoglycosides with individual cephalosporins are discussed.

Prevention and treatment of nosocomial infections, with special reference to antibiotic policy.

Hospital infections are of a major and growing health concern worldwide. They are the cause of appreciable economic loss, but what raises the particular alarm, both ethically and as a public health problem, is their continuous trend towards increasing lethality. The incidence of nosocomial infections can be prevented by creating a system of barriers that would interrupt their spread and transmission. Apart from strict adherence to general hygiene rules and the rational employment of examination methods it is essential in this respect that a prime attention is paid to the sensible use of antimicrobials, i.e. the persuance of a sound antibiotic policy. Its integral components are the systematic laboratory control, continuous epidemiological surveillance of bacterial drug resistance patterns, study of variations in the biological properties of multiple resistant bacterial strains, and the development of, and adherence to, effective and indicated treatment schedules. The particular problems related to bacterial enzyme activities and the genetic information (plasmids) coding for resistance to antimicrobials, as well as the virulence and pathogenicity of agents responsible for the onset of hospital infection are also discussed in this context. It is pointed out that for an effective hospital infection control it is essential to avoid the onesided pressure of badly applied antibiotic therapy.

Long-term experience with combined action of antibacterials.

The authors have obtained good results in control of respiratory infections in children (aged 3-9 years) (especially those with dg. pneumonia) when applying a combination of amoxicillin with clavulanic acid. Correct indication has enabled them to shorten the period of treatment by means of this combination. The interaction of ticarcillin with some aminoglycoside preparation has been verified in vitro. Synergic action has been found to be high.

In vivo effect of aminoglycoside on Pseudomonas aeruginosa in experiment.

In artificial pseudomonas infections undertaken on white mice the effectiveness of the aminoglycosides (gentamicin, tobramycin, netilmicin, amikacin) was compared. The most effective drugs on highly susceptible Ps. aeruginosa were amikacin and netilmicin. Moreover amikacin is probably capable of inhibiting pseudomonas toxin production. Therefore this preparation should be left in reserve for the treatment of serious pseudomonas processes.

Haemophilus influenzae: the current status of its in vitro susceptibility to antimicrobials.

Continuous surveillance of the antimicrobial susceptibility patterns of strains of Haemophilus influenzae (H. i.) is part of a routine surveillance of bacterial sensitivity to antibiotics. In this study a major attention was given to the clinically important antimicrobials used in the treatments of H. i. infections, namely ampicillin, chloramphenicol and some cephalosporin preparations. Antimicrobial susceptibility determinations carried out in 1983 and before on H.i. strains isolated in different Czech regions show a clear-cut tendency towards the higher incidence of strains resistant to ampicillin and its derivative amoxycillin. The rise in resistance to erythromycin was also observed. Susceptibility to chloramphenicol continues to remain unchanged. Of the cephalosporin antimicrobials tested (cephalothin, ceftriaxone, cefaperazone, cefsulodine and cefadroxil) the most active were ceftriaxone and cefaperazone. The need of a further continuation of surveillance of H.i. drug susceptibility patterns is strongly emphasized; to ensure effective treatment results antibiograms should be done in each case of H.i. infection.

Phage plaques and autoplaques in Pseudomonas aeruginosa strains.

Studies were made on the morphological variety in plaques produced by phage lysis and autoplaques in Pseudomonas aeruginosa strains. The great variability of phage plaque morphology may lead to a confusion with the autoplaques produced spontaneously by P. aeruginosa strains. The production of autoplaques is characteristic of a large number of clinical strains of P. aeruginosa. The appearance of autoplaques may complicate analysis of significant clinical strains of P. aeruginosa.

Administration of antibiotics in combination. The antibacterial activity of blood serum and urine after a simultaneous administration of aminoglycosides and ampicillin.

Blood serum and urine samples collected from a group of volunteers treated with single doses of ampicillin and aminoglycoside preparations given separately or in combination were tested for their antimicrobial activity against the reference strains Staphylococcus aureus SZK 76/69 and ATCC 6538, Pseudomonas aeruginosa SZK 444 and SZK 385, and Escherichia coli SZK 326/71. Out of all antimicrobials and their combinations tested the most powerful was the combination of netilmicin with ampicillin. Of the therapeutic combinations used nowadays in clinical practice the combined use of gentamicin and ampicillin proved also effective. These antibiotic combinations appear thus to be best suited for the treatment of mixed Pseudomonas aeruginosa and Staphylococcus aureus infections and of urinary tract infections caused by bacterial strains exhibiting in the in vitro susceptibility assays a reduced sensitivity to some of the antibiotic preparations used.

Pseudomonas aeruginosa. I. Large-volume cultivation of production strains for vaccination purposes.

A submerged culture technology was used to produce large-volume suspensions of Pseudomonas aeruginosa production strain for the purpose of vaccination. This paper describes the composition of the culture media used and the methods of preparing endotoxin and exotoxin components of the desired immunogenic activity.