Bacillus cereus endophthalmitis.

Endophthalmitis, of any aetiology, is a potentially devastating ocular infection. Few patients are able to maintain good visual acuity. Many retain only navigational vision and a significant number require evisceration or enucleation. 2 The incidence ofendophthalmitis after trauma has been estimated to occur in 2-7% of cases.3 Various organisms have been implicated but, in recent years, Bacillus cereus has emerged as a particularly virulent organism. Its significance, however, has not always been appreciated. Part ofthe problem has been related to difficulties in subclassification within the genus Bacillus. During the first half of this century bacilli isolated from cases of endophthalmitis were often not subclassified beyond Bacillus species and many were grouped as Bacillus subtilis by default. In 1948, Bergey set out new criteria to distinguish Bacillus cereus from Bacillus subtilis. Four years later, in 1952, Davenport and Smith reported the case of a man who lost his eye subsequent to culture proved B cereus endophthalmitis. The clinical course described was malignant. Similarities could be drawn between Davenport's case and series reported as early as 1891 by Poplawska, and later by Francois in 1934. The isolate in those series was thought to be B subtilis, but this may have been an error of taxonomy.4 A further confounding factor to the recognition ofB cereus as a destructive ocular pathogen is that it is often found as a contaminant in culture. In 1981, O'Day and his colleagues highlighted the importance of B cereus in post-traumatic endophthalmitis which, if grown on culture, should be considered as the primary infectious agent. They suggested that suspicions should be raised if there was a history of soil contamination involving a metallic foreign body.5 Whereas B cereus was being increasingly recognised in exogenous, post-traumatic endophthalmitis, numerous cases of endogenous endophthalmitis relating to B cereus had already been reported in the literature."3 The infections were linked with the transfusion of contaminated blood products and the use of illicit intravenously administered drugs. Shamsuddin et al, in 1982, found that the source of the organism was either the illicit drug itself or the paraphernalia used to inject the substance." The bacteraemia associated with the use of contaminated drugs and instruments has also been reported to be the cause of other serious forms of infection including endocarditis, osteomyelitis, meningitis, and necrotising fasciitis.'4 B cereus is well established as a pathogen in the food industry. It is a spore forming bacterium and therefore resistant to temperatures attained during many cooking methods.'5 The spores germinate when heated food for example, rice, is left unrefrigerated. Brief rewarming is not adequate to destroy the preformed, heat stable toxin. There are two recognised patterns of food poisoning. The first has an incubation period of 8 to 16 hours before the onset of abdominal cramps and profuse, watery, diarrhoea. The second became recognised in the 1970s and was associated with rice purchased from Chinese 'take aways'. The rice would often be prepared in advance and kept at a relatively high temperature. This allowed the bacteria to thrive and counts in the region of 106 to 109 per gram of rice have been isolated in proved cases. Typically, nausea and vomiting would develop 1 to 5 hours after consumption. 6 In this paper we describe the clinical and bacteriological features ofB cereus endophthalmitis and discuss management controversies in current clinical practice.