On the Importance of Bacterial L‐Forms in Pigeons*

Following a definition of bacterial L-forms and a literature review on introduction and reversion of bacteria to and from L-forms, respectively, the results of a study comprising 587 samples (316 pigeons and 271 pigeon eggs) are reported. As a control 25 free living pigeons and 25 eggs of those pigeons were used, because antibiotic treatment of these could be excluded. From 79 samples (75 pigeons and 4 eggs) Salmonella typhimurium var. copenhagen (STMC) was isolated (none from the urban pigeons), of them 11 in the L-form from joints and organs and 3 from eggs. 325 of other bacterial isolates were found as L-forms (= approx. 40%). Out of 168 serum samples investigated, 33.9% showed antibodies against STMC. Corresponding antibodies could only be demonstrated in 73.4% of the pigeons with a STMC isolate. The occurrence of L-forms explains resistance to therapy and the failure of vaccines. The high frequency of L-forms is probably an indication of an inconsequential use of antibiotics in managing pigeon diseases.