Some antimicrobial compounds were tested for their antiplaque activity by a simple method involving measurement of the weight of Streptococcus sobrinus plaque on a glass surface. Chlorhexidine, cetylpyridinium chloride, and n-tetradecylamine reduced the weight of plaque produced by S. sobrinus in vitro; some N-palmityl and palmitoyl derivatives of polymethylenediamines were also found to possess antiplaque activity. The results suggest that an antiplaque effect does not necessarily depend on high bactericidal activity.

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ABSTRACT. On-farm vaccination of chickens against Campylobacter jejuni is considered a potentially effective countermeasure to decrease campylobacteriosis via consumption of contaminated chicken meat, but is not yet available. In this study, 2 groups of Jidori chicks were immunized subcutaneously with a formalin-killed C. jejuni with 2 different adjuvants. Other chicks served as the unvaccinated control group. Both vaccines induced high levels of anti-Campylobacter IgG but did not decrease bacterial excretion in cecal droppings and bacterial load in the liver and spleen after oral challenge with 10 5 CFU of the homologous strain. Further study is needed to address the observed irrelevance and to develop a novel effective vaccine against C. jejuni.

A racing pigeon (Columba livia var. domestica), a straggler from Taiwan, was sheltered in Nara Prefecture Japan in 2020. This pigeon showed hemolysis and elevated levels of hepatobiliary and muscle enzymes. Gametocytes of Haemoproteus columbae (Apicomplexa: Haemosporida) were observed within the host erythrocytes in thin blood smears. A partial sequence of the mitochondrial cytochrome b gene amplified from blood DNA was identical to the lineage HAECOL1 previously reported from pigeons worldwide. This is the first record of H. columbae infection in a sheltered bird in Japan.

The haemolytic action of various N-alkyl derivatives (lauryl; C12H25-, myristyl; C14H29-, palmityl; C16H33-) of 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentate, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane was examined using rabbit red blood cells. The activities of the various derivatives were compared with those of antiplaque agents commonly used as mouthwashes; cetylpyridinium chloride (CP) and chlorhexidine acetate (CH). The haemolytic activities of these agents were dependent on the length of the N-alkyl chain, whereas the number of methylene groups between the nitrogen atoms had little effect. The order of potency was CP, N-palmityl derivatives, N-myristyl derivatives greater than N-lauryl derivatives greater than CH which was similar to the order of the antiplaque effect evaluated in-vitro.