The influence of antibiotics on experimental moniliasis

Summary

The effects of the intraperitoneal administration of oxytetracycline and chlortetracycline on mice of strain CBA each inoculated by the same route with 6 million cells ofCandida albicans were assessed primarily on the basis of histological examination. An injection of oxytetracycline given at a dosage of 2.5 mg two hours after fungal inoculation, and repeated 24 hours later, resulted in the appearance of enhanced forms of systemic infection as indicated by early mortality. Enhancement of infection was referred to two forms:—1. Degenerative enhancement determined the deaths of some animals following the appearance of cloudy swelling in the cellular elements of the heart and kidneys, and was not related to the degree of fungal colonisation, which was frequently meagre or occasionally absent.

2. Colonial enhancement was regarded as involving a rapid colonisation of the tissues of the heart and kidneys by a pseudomycelial growth form of the fungus. In this type of infection, histological evidence of an impairment of leucocytic function in the host was obtained.

Inoculated mice, previously treated with oxytetracycline or chlortetracycline (both at dosages of 2.5 mg) and variously treated 2 to 72 hours later with these antibiotics, gave no evidence of enhancement of infection. Both antibiotics, however, contributed to an increase in regional infection within the peritoneal cavity. Multiple regional infection was increased by 60% by the use of oxytetracycline, and by 50% by the use of chlortetracycline. The percentage of systemic disease reactions rose in inoculated animals receiving oxytetracycline: it fell significantly where chlortetracycline had been employed, denoting the existence of protection from systemic infection.

Both enhancement of and protection from infection were viewed as manifestations of the modification of a basic, systemic mechanism of host defence.