MICROBIOLOGY I

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Abstract

Knight (1972) could review experimental fungal infection of the skin without once referring to the ethical aspect. With bacterial infections this is not possible. To dip into the horrors of the past, I recommend Dowling (1966) on most infections, and Hill (1943) on the gonococcus. Most of the trouble has been with systemic infections, but experimenters who infect the skin must be on their guard too. Even the mild Serratia marcescens {Chromobacterium prodigiosum), a favourite biological marker on the skin, with its coloured colonies a great help to the less skilled, shows its teeth if given a chance (Ringrose et al., 1968). The problems are much worse with Staphylococcus aureus. Ethics did not bother the brave Garre (1885) or Bockhart (1887) when they rubbed strong cultures of staphylococci into their own arms. Garre's carbuncle and Bockhart's superficial foUiculitis hurt no one but themselves, though Bockhart might have been warned by his previous study—an experimental infection with gonococci of the urethra of a man with dementia paralytica, who had died with renal abcesses 10 days later (Hill, 1943). No wonder that studies turned rapidly to the subject of the survival of organisms on the skin, so well reviewed by Rebell et al. (1950), rather than to further attempts to create septic lesions. The arrival of antibiotics was comforting, and experiments were resumed, but later workers again ran into trouble. Elek & Conen (1957), in their most valuable study of the minimal pus forming dose, gave one volunteer chronic furunculosis. Another formed two large abcesses which, in spite of penicillin therapy, 'progressed to the size of an orange, causing fever and other systemic manifestations'. Foster & Hutt (i960) used three subjects^ two developed boils and abcesses which persisted for several weeks after they had been forced to stop the study. Duncan, McBride & Knox (1970), stabbing with a lancet through a mixture of Staph. aureus and Streptococcus pyogenes, produced six severe abcesses. Despite this, Singh, Marples & Kligman (1971) still felt that 'the record of attempts to induce infections with cultures or lesional material is one of astonishing disappointment'. But in the early part of their own study, three subjects showed 'hot, tender furunculoid nodules around the infection site a few days after removing the dressings. Two of these had lymphangitis, axillary lymphadenopathy, and a modest increase in temperature.' After this, their regime was to give each subject erythromycin or tetracycline systemically when the infected areas were biopsied. Antibiotics were also used for any subject with a fever of over 39'5°C. The case for doing human experiments is that animal data do not apply to man. The virulence of an organism depends on the species it is attacking; a fact used, for example, to tell the human and bovine strains of tuberculosis apart by their different effects on the guinea-pig and the rabbit. This is clearly true; but the high cost of human work—and Pappworth (1969) has something to say about the use of