Ramon Pares

Enhancement of the Humoral Immune Response and Resistance to Bacterial Infection in Mice by the Oral Administration of a Bacterial Immunomodulator (OM-89)

We investigated the effects of an Escherichia coli-derived product (OM-89) in mice. The oral administration of OM-89 led to a significant (p less than 0.05, Students t test) increase in the levels of IgA in intestinal secretions, which was at maximum 25 days after the end of the treatment, when a two-fold increase in IgA levels was observed. The i.p. inoculation of OM-89 induced the stimulation of anti-SRBC plaque-forming cells (PFC) in the spleen. The effect of OM-89 was dose-dependent and produced up to a 9-fold increase in PFC in the treated mice when compared to untreated controls. The oral administration of OM-89 proved to be effective in the enhancement of resistance to challenge i.p. inoculation with E. coli. 32% of OM-89-treated mice showed resistance to this experimental infection at minimal LD100. The combined effects of low environmental temperature and cyclophosphamide (CY) immunosuppression enabled us to enhance differences in survival rates in experiments on the modulation of resistance towards Pseudomonas aeruginosa infection. The oral treatment with the immunomodulator induced a significant (p less than 0.05, Students t test) level of protection in CY-immunosuppressed mice to the intranasal infection with P. aeruginosa, when mice were kept at low environmental temperature right after the bacterial challenge. The protective effect of OM-89 treatment was dependent on both the environmental temperature and the timing of the experiment.

Compensation of Cyclophosphamide Immunosuppression by a Bacterial Immunostimulant (Broncho-Vaxom) in Mice

The compensatory effect of a bacterial lysate, Broncho-Vaxom (BV) on the immunosuppressive action of cyclophosphamide (CY) was investigated. In CY immunosuppressed mice, BV treated animals recovered to normal levels of IgM and IgG in serum as well of IgA and IgG in gut secretions significantly earlier than controls. Furthermore, normal cell proliferation in thymus, as estimated by measuring the relative size of this organ was achieved earlier in BV treated mice than in control mice. Oral treatment with BV restores the number of IgM anti SRBC producing cells in spleen, in CY immunosuppressed mice. Since immunosuppression induced by CY increases the susceptibility to various infections, we tested in immunosuppressed animals the protective effect of BV towards IP challenge infections with Streptococcus pneumoniae, Staphylococcus aureus, Klebsiella pneumoniae var ozaenae, Pseudomonas aeruginosa and Candida albicans. BV led to an enhanced resistance towards both pneumococci and staphylococci challenge infections but not to the other challenge microorganisms.

Bacterial Immunostimulant (Broncho-Vaxom) Versus Levamisole on the Humoral Immune Response in Mice

A comparative study on the enhancement of humoral immune response in mice after oral treatment with levamisole or a lyophilized bacterial lysate (Broncho-Vaxom) is presented. The latter proves to be more effective at therapeutic doses than levamisole on the induction of immunoglobulin formation and particularly that of IgA in secretions.

Inhibition of two imidazole antimycotics, eberconazole and clotrimazole, by different components of Candida albicans serotype B membrane protoplasts

The inhibitory activity of different components from Candida albicans membrane protoplasts against clotrimazole and eberconazole was studied. The phospholipid fraction had the most inhibitory activity and the antimycotic activity of eberconazole was more affected than that of clotrimazole.

Isolation and partial characterization of phages infectingCitrobacter intermedius C3

Several new bacteriophages infecting strain C3 ofCitrobacter intermedius have been isolated from fresh waters. The physicochemical properties, plaque morphology, growth characteristics, virion structure, and immunology of eight bacteriophage isolates are reported. The phages are classified into three groups according to their characteristics.

Citrate utilizing ability linked to glutamic acid excretion governing conjugative plasmid in Klebsiella pneumoniae C3

Summary The citrate utilizing ability (Cit + ) in Klebsiella pneumoniae C3 was simultaneously lost with the abilities to excrete glutamic acid and to biosynthesize proline. Both properties were proved to be plasmid determined ( J. Jofre et al., J. Bact. 138 , 721–725). Citrate utilization was transferred by conjugation from K. pneumoniae C3 to Escherichia coli K12. Moreover, the transfer of the ability to biosynthesize proline from strain C3 to well-characterized Pro- strains of E. coli established that loci pro A and pro B, but not pro C, are complemented by the plasmid herein described. E. coli exconjugants transferred simultaneously the abilities to utilize citrate and to biosynthesize proline by conjugation to other E. coli strains. Plasmid DNA was detected in E. coli exconjugants either by cesium chloride-ethidium bromide ultracentrifugation or by agarose gel electrophoresis. Gel profiles established that a single plasmid of an estimated molecular weight of 57 megadaltons is present in all examined E. coli exconjugants. Pro − E. coli were transformed to Pro + Cit + with plasmid DNA of exconjugants. Also, a Cit - , Pro − and non-glutamic acid excreting strain derived from C3 was rendered Cit + , Pro + and glutamic acid excretor by transformation with plasmid DNA from E. coli exconjugants. Therefore it can be concluded that the three phenotypic characteristics above mentioned are complemented by a single conjugative plasmid.

Survey of viral pollution in Duero River (Spain): Occurrence of natural virucidal phenomena

Abstract A 17-month survey was undertaken to monitor the occurrence of enteroviruses at five sampling stations along the Duero River, in the vicinity of Soria. Total aerobic bacteria, total and fecal coliforms and fecal streptococci, together with several physicochemical parameters were also analysed. Although all the bacterial populations under study correlated to each other, no correlation was demonstrated between virus levels and any other parameter. Virus depuration processes were verified to occur. The river acquires a high level of fecal contamination after the discharge of a heavily contaminated urban sewage outfall. A progressive decrease in virus levels was observed along the river course, showing the effectiveness of natural virus inactivation phenomena occurring in the river.