A comparative study of preservation and storage of Haemophilus influenzae

The aim of this study was to compare the efficacy of conservation by freezing the strains of Haemophilus influenzae at -20ºC and -70ºC. Skim milk supplemented with glucose, yeast extract and glycerol allowed highest viability of H. influenzae both at -20ºC and -70ºC from the media analyzed. Trypticase soy broth and brain heart infusion broth supplemented with glycerol, allowed excellent recovery. Use of cotton swaps as supporting material, with or without addition of cryoprotective agents, did not modify H. influenzae viability after six months of storage. Concentration of the initial inoculum positively affected viability when stored at -20ºC. Initial concentration did not influence survival after storage at -70ºC. Thawing at room temperature should not exceed 3 h as to get highest survival percentage

In vitro comparison of disk diffusion and agar dilution antibiotic susceptibility test methods for Neisseria gonorrhoeae

At present, most Neisseria gonorrhoeae testing is done with Beta-lactamase and agar dilution tests with common therapeutic agents. Generally, in bacteriological diagnosis laboratories in Argentina, study of antibiotic susceptibility of N. gonorrhoeae is based on Beta-lactamase determination and agar dilution method with common therapeutic agents. The National Committee for Clinical Laboratory Standards (NCCLS) has recently described a disk diffusion test that produces results comparable to the reference agar dilution method for antibiotic susceptibility of N. gonorrhoeae, using a dispersion diagram for analysing the correlation between both techniques. We obtained 57 gonococcal isolates from patients attending a clinic for sexually transmitted diseases in Tucuman, Argentina. Antibiotic susceptibility tests using agar dilution and disk diffusion techniques were compared. The established NCCLS interpretive criteria for both susceptibility methods appeared to be applicable to domestic gonococcal strains. The correlation between the MIC's and the zones of inhibition was studied for penicillin, ampicillin, cefoxitin, spectinomycin, cefotaxime, cephaloridine, cephalexin, tetracycline, norfloxacin and kanamycin. Dispersion diagrams showed a high correlation between both methods.

Properties of ß-lactamase from Neisseria gonorrhoeae

ß-lactamase activity was studied in Neisseria gonorrhoeae strains. Optimum temperature was found to be 37ºC. The enzyme was inactivated at temperature higher than 60ºC, but remained active during storage at low temperatures (4ºC, -30ºC and -70ºC) for two months. Enzyme activity was observed within a pH range of 5.8-8.0, while the optimum pH was 7.0-7.2. Addition of Ni²+, Fe²+, Fe cube number +, Mn²+ and p-chloromercurybenzoate to the reaction buffer exerced a negative effect upon the activity, whereas Hg²+ and ethylene diamine tetra-acetic acid produced complete inhibition. These results would indicate the presence of -SH groups at the catalytic site of the enzyme.

Agar dilution method for susceptibility testing of Neisseria gonorrhoeae

The antibiotic susceptibilities of Neisseria gonorrhoeae isolates obtained from patients attending a clinic for sexually transmitted diseases in Tucuman, Argentina, were determined by the agar dilution method (MIC). 3.5 per cent of the isolates produced ß-lactamase. A total of 96.5 per cent of ß-lactamase negative isolates tested were susceptible to penicilin (MICó2 µgml-1); 14.03 per cent of the tested isolates were resistant to tetracycline (MICó 2 µgml-1), and 98 per cent of the tested isolates were susceptible to spectinomycin (MICó 64 µgml-1). The MICs for 95 per cent of the isolates, tested for other drugs were: ó µgml-1 for cefoxitin, ó0.06 µgml-1 for cefotaxime, ó0.25 µgml-1 for norfloxacin, ó 10 µgml-1 for cephaloridine, ó 10 µgml-1 for cephalexin and ó50 µgml-1 for kanamycin. Antibiotic resistance among N.gonorrhoeae isolates from Tucuman, Argentina, appeared to be primarily limited to penicilin and tetracycline, which has been a general use against gonorrhoeae in Tucuman since 1960. Periodic monitoring of the underlying susceptibility profiles of the N.gonorrhoeae strains prevalent in areas of frequent transmission may provide clues regarding treatment options and emerging of drug resistance.

Detección de factores de adhesión en Neisseria gonorrhoeae mediante reacciones de hemoaglutinación / Detection of adhesive factors in Neisseria gonorrhoea by reactions of the magglutination

De acuerdo a Kellogg, Neisseria gonorrohoeae en cuatro (4) tipos. Los dos primeros son virulentos (T1 y T2). Se responsabiliza de este efecto a factores de adhesión (fimbria o pili) quienes permiten la colonización. En el presente estudio se pone en evidencia dichos factores por medio de reacción de hemoglutinación. Se trabajó con 89 cepas de aislamientos recientes obtenidas de pacientes con diagnóstico clínico de gonorrea; se utilizó la microtécnica en portaobjetos descripta por Koransky y colaboradores. Los ensayos se realizaron con eritrócitos pertenecientes a distintas especies y tipos sanguíneos. Se demonstró que los resultados no se modifican cuando se varía la procedencia o tipo de glóbulos rojos usados. Paralelamente, con sueros humanos antigonocócicos se efectuó la reacción de inhibición de hemoglutinación (IHA) frente a las cepas aisladas. Se confirma con estas pruebas la presencia de pili