Sensitivity of clinical Proteus strains to antibiotics and their combinations]

In 1976 isolation of Proteus from wounds of patients with various purulent processes amounted to 14.5 per cent. Serotypes 0-10, 0-3 and H-3 predominated among the isolates. Sensitivity of 35 clinical strains of Proteus to 10 antibiotics, furagin and nevigramone was studied by the method of serial dilutions in liquid media. All the isolates were highly resistant to the antibiotics except gentamicin, furagin and nevigramone, the MIC of which for most of the strains was 3.12, 1.6-3.12 and 6.25-12.5 gamma/ml, respectively. The effect of 14 combinations of chemotherapeutics was also studied. The combinations of gentamicin with carbenicillin, gentamicin with ampicillin and monomycin with ampicillin proved to be most effective against the Proteus strains tested. The following combinations may be of practical value: monomycin + carbenicillin, kanamycin + ampicillin, kanamycin + carbenicillin, ampicillin + furagin, gentamicin + nevigramone. The combinations of carbenicillin with furagin and gentamicin with furagin were also rational.     

Sensitivity of Brucella melitensis to various antibiotics, drug preparations and their combinations

In vitro activity of 13 antibiotics and drug preparations as well as some of their combinations was studied with respect to Brucella melitensis. It was shown that the strains of B. melitensis were sensitive to sisomicin, amikacin, gentamicin, cefotaxime, rifaprim +, nitroxoline and trimethoprim. Variations in the doxycycline sensitivity depending on the strain were observed. The strains of B. melitensis were resistant to cephalexin, phosphomycin, chinoxydine, dioxydine and oxolinic acid. Combinations of sisomicin and trimethoprim at a ratio of 1:10 and sisomicin and nitroxoline at a ratio of 1:2 had a summation effect.     

Resistance of hospital Staphylococci to beta-lactam antibiotics]

Resistance of hospital Staphylococci to beta-lactam antibiotics was studied. The strains were isolated in two obstetric hospitals during an outbreak of purulent inflammatory infections in them. A modification of the "clover leaf" procedure providing elucidation of the resistance mechanism was used in the study. Development of the resistance to the beta-lactam antibiotics was shown to be mainly due the activity of beta-lactamases which makes it possible to discuss their role in the mechanism of resistance development.     

In vitro activity of beta-lactam antibiotics and their sensitivity to beta-lactamase

beta-lactamase production was evaluated by chromogenic cephalosporin 87/312 in 116 E. coli isolated from clinical sources. Such test revealed beta-lactamase production in 54 strains out of 116 (46%): MICs of eight beta-lactam antibiotics (Ampicillin, Piperacillin, Cefazoline, Cephaloridine, Cephalexine, Cefuroxime, Cefotaxime, Cefotaxime) were determined using a miniaturized dilution broth method. Cefotaxime and Ceftriaxome and Ceftriaxone showed the highest antibacterial activity. All beta-lactamases produced by E. coli strains under examination were isolated and purified by ultrasonic disruption and high speed centrifugation. Sensitivity of the eight antibiotics to purified beta-lactamases was assessed by a spectrophotometric method that utilizes the velocity of cytochrome c reduction. The sensitivity to beta-lactamases was reflected in the in vitro activity of the antibiotics as assessed by the determination of the MICs.