Sensitivity of bacteria of the genus Acinetobacter to antibiotics and ofloxacin

Between 1989-1989 276 strains of Acinetobacter genus were isolated which contained: Acinetobacter calcoaceticus subsp. anitratus (n = 167), Acinetobacter calcoaceticus subsp. Iwoffi (n- = 83), Acinetobacter haemolyticus (n = 26). Their sensitivity to aminoglycoside antibiotics, beta-lactams, tetracyclines, chloramphenicol, colistin, and ofloxacin was tested. More than 90% of strains were sensitive to colistin and ofloxacin. The sensitivity to remaining antibiotics differentiated depending on species. Acinetobacter anitratus were highly resistant to Ist and IInd generation of cephalosporins, and moreover to penicillins, tetracyclines, and chloramphenicol. Cephalosporins of IIIrd generation were active against 70% of strains with exception of cefoperazone what was also the case for representatives of aminoglycosides as netilmicin and amikacin. Strains of Acinetobacter Iwoffi were in majority sensitive to all antibiotics with exception of cephalothin, cephradine and cefoperazone. More than 90% of Acinetobacter haemolyticus strains were sensitive to gentamicin, carbenicillin, azlocillin, ceftriaxone, cefotaxime and tetracyclines.     

Sensitivity of aerobic bacteria and Candida species to chlormidazole hydrochloride in vitro

Over 100 bacterial stains, including Candida sp., gram-positive cocci and some gram-negative bacilli, were tested. The majority of microorganisms was isolated from man. Only one bacterial strain (5 micrograms/mL) and 76% of Candida strains were sensitive to chlormidazole HCl (10 micrograms/mL). It may be assumed that most infections with Candida sp. will respond to therapy with drugs containing chlormidazole HCl. Relatively simple and inexpensive tube test may serve to evaluate microbial sensitivity to this agent, especially in case of isolates from patients.     

An in vitro polypeptide synthesizing system from methanogenic bacteria: Sensitivity to antibiotics

Summary An in vitro polypeptide synthesis system was set up for three methanogenic bacteria, Methanococcus vannielii, Methanobacterium formicicum and Methanosarcina barkeri, and the effect of classical 70S and 80S protein synthesis inhibitors studied. The following results were obtained: (i) The activity of ribosomes from all three methanogens was unaffected by a number of 70S inhibitors such as tetracycline, chloramphenicol, streptomycin, tiamulin and, probably, erythromycin as well; (ii) However, the ribosomes were sensitive to thiostrepton, virginiamycin and, to varying degrees, to those aminoglycosides containing a 2-deoxystreptamine moiety. Among the aminoglycosides examined, streptomycin induced no translational misreading. The compounds containing 2-deoxystreptamine stimulated misreading, albeit only at high concentrations (neomycin being an exception); (iii) Ribosomes from all three organisms were insensitive to the 80S inhibitors cycloheximide and ricin, but those from Methanobacterium formicicum were highly sensitive to anisomycin and moderately sensitive to verrucarin. The results support those of in vivo studies and provide conclusive evidence that archaebacterial ribosomes despite being 70S ribosomes lack binding sites for many classical eubacterial ribosome inhibitors. At the same time they possess sites for others, as well as for some inhibitors of 80S ribosomes.     

Sensitivity of Shigella to antibiotics]

Three hundred and twenty two Shigella cultures isolated from dysentery patients within 1986-1989 were tested with the use of standard paper disks for their sensitivity to levomycetin, streptomycin, tetracycline, monomycin, neomycin, kanamycin, erythromycin, gentamicin, carbenicillin, ampicillin, oxacillin, methicillin and doxycycline. The number of the cultures belonging to Shigella sonnei amounted to 85.1 per cent of the total number of the strains studied. 91.9, 89.5, 87.3, 87.3, 80.1 and 80.1 per cent of the cultures were sensitive to gentamicin, kanamycin, carbenicillin, neomycin, levomycetin and ampicillin, respectively. 99.4 per cent of the isolates were resistant to streptomycin and 97.2 per cent were resistant to tetracycline. The sensitivity to erythromycin remained rather high (70.2 per cent). The overwhelming majority of the Shigella sonnei isolates had multiple resistance.     

Sensitivity of bacteria exposed to subinhibitory concentrations of antibiotics to the action of serum and liver phagocytes

Incubation of E.coli and S. aureus with subinhibitory concentration (1/5 MIC) of cefamandole modified bacterial morphology and resistance to host defence mechanisms. In fact, cefamandole induced filamentous forms of E. coli, when added to the perfusing medium of the isolated rat liver system, were phagocytized at a much fortes rate then control bacteria, but appeared less sensitive to serum bactericidal activity. In contrast, S.aureus, after exposure to the antibiotic, was more sensitive to the bactericidal activity of serum then controls, while treated and untreated cells were phagocytized at the some rate. The data suggest that even at low doses some antibiotics may alter bacterial structure and increase their susceptibility to host factors.