Activity of cefotaxime and amikacin against 14,272 gram-negative bacteria from clinical samples in the period 1980 to 1985.

The sensitivity to cefotaxime and amikacin of 14,272 Gram-negative bacilli (Enterobacteriaceae and non-fermenting Gram-negative bacilli) isolated from clinical samples was studied during the period 1980 to 1985. The minimum inhibitory concentration (MIC) was determined by means of diffusion in agar. Strains were considered resistant to cefotaxime and amikacin if the MIC values were greater than 16 mg/L and greater than 8 mg/L, respectively. The MIC90 reached the critical value for cefotaxime in the case of Citrobacter spp., Escherichia coli, Klebsiella spp., Proteus mirabilis, Salmonella spp. and Shigella spp., and for amikacin in the case of Citrobacter spp., Enterobacter spp., E. coli, Klebsiella spp., P. mirabilis, Proteus vulgaris, Salmonella spp. and Serratia spp. Only Shigella spp. were sensitive to cefotaxime but not to amikacin, and only strains of Enterobacter spp. and Serratia spp. were sensitive to amikacin but not to cefotaxime.

[Comparative study of different serological tests for the diagnosis of brucellosis (author's transl)]. / Estudio comparativo de diversas pruebas en el diagnóstico serológico de la brucelosis.

The diagnosis of brucellosis is frequently a difficult one, and it is founded basically on the results of blood cultures and serological tests. Wright's classical agglutination test is commonly utilized in the serological diagnosis of brucellosis and its value is well established in the acute forms of the disease; for the diagnosis of subacute or chronic forms, however, a Coombs test must be performed to show incomplete antibodies. The agglutination carried out with serum treated with 2-mercaptoethanol allows the determination of the type of immunoglobulins present. Indirect immunofluorescence has been infrequently utilized in the diagnosis of brucellosis. The first three tests have been compared with indirect immunofluorescence using sera from 100 patients presenting with fever of unknown origin. All tests were negative in 40 sera, and of the 60 remaining sera only 32 were positive to all four tests. The highest titers were found with the Coombs test, while immunofluorescence yielded titers which were never above 1/320. Significant correlation coefficients were obtained between the tests. The best correlation was obtained between immunofluorescence and 2-mercaptoethanol, followed by immunofluorescence and Coombs, and by immunofluorescence and agglutination. Only immunofluorescence titers above 1/80 corresponded to the same of superior titers in the remaining tests; thus immunofluorescence titers below 1/80 can not be considered as diagnostic of the disease. The authors believe that immunofluorescence to 1/80 can be utilized as a quick routine test for the diagnosis of brucellosis, its disadvantages being a high cost and the requirement for an immunofluorescence microscope which may not be available in many laboratories.

The effect of minocycline, doxycycline and oxytetracycline on experimental mouse toxoplasmosis.

This is a comparative study of the effect of oral and parenteral administration of oxytetracycline, doxycycline and minocycline on experimental acute toxoplasmosis in mice. Two different inocula were used. All the antibiotics were ineffective orally. Doxycycline and minocycline were effective intraperitoneally, curing 90% of the mice who received the smaller inoculum. However, cerebral cysts of T. gondii were more common in the survivors treated with doxycycline.

Genetic localization of the resistance to fosfomycin.

The possible existence of a transferable resistance to fosfomycin was studied in 50 strains of enterobacteria that were isolated in our hospital and which showed a resistance to fosfomycin of more than 256 mug/ml. E. coli K12 E711 was used as a receptor strain in the conjugation -- the times of conjugation were 20 min and 18 h. We found a transferable resistance in 28% of the strains. In all but one of the cases, only the resistance to fosfomycin was transferred. The recombinant which received the resistance to fosfomycin together with three other resistances was used as the donor for the transduction with the phage P1Kc to the receptor strain which was E. coli UTH 1038. A study was carried out on the influence of the radiation of the transducing phages with ultraviolet light on the frequency of transduction. The findings demonstrated a linear decrease in the frequency in proportion to the increase in the time of radiation.

[Bacteremia associated with mycotic aneurysm of the transversal aortic arch and myocarditis caused by Salmonella enteritidis]. / Bacteriemia asociada a aneurisma micótico de arco aórtico transverso y miocarditis por Salmonella enteritidis.

A 60-year-old male with diabetes mellitus had Salmonella enteritidis bacteremia associated with mycotic aneurysm of the transverse aortic arc and myocarditis. Antibiotic therapy with ampicillin and chloramphenicol was ineffective despite the fact that the microorganism was sensitive in vitro to those antimicrobials, and the patient had a progressive clinical deterioration which culminated in death.