SUMMARY This appears to be the first report of meningitis due to Pseudomonas paucimobilis and the first report of a clinically significant isolate of this species in the UK. Characteristics by which the species may be recognised are given, and attention is drawn to the possible confusion of Ps. paucimobilis with other yellow-pigmented pseudomonads and Flavobacterium species.Pseudomonas paucimobilis is a species described only recently (Holmes et al., 1977). The strains on which the description of the species was based had been recovered largely from human clinical specimens and the hospital environment, but none was known to be the causative agent of infection. Although the clinical significance of Ps. paucimobilis remained unknown we now report what is, as far as we know, the first case of meningitis due to this species. Case reportA 39-year-old male epileptic was admitted on 24 June 1978. He had had epilepsy for three years and was currently treated with phenobarbitone 60 mg and phenytoin 100 mg three times a day. He complained of headache for two days and had started to have convulsions on the day of admission. This was controlled with a single dose of 20 g diazepam intravenously. However, he remained very drowsy 6 hours later, and the axillary temperature was found to be . Clinical examination showed neck stiffness and a positive Kernig's sign.A lumbar puncture was performed and turbid fluid obtained, giving the following results: white cells 0-2 x 109/1 (200/mm3), 95 % lymphocytes, 5 % neutrophils; protein 0 4 g/l (40 mg/100 ml), glucose 3-7 mmol/l (67-2 mg/100 ml); the blood glucose level was 4-7 mmol/l (85 mg/100 ml). Gram and ZiehlNeelsen films were initially reported as negative.

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The results of the identification of 933 strains of Gram-negative, aerobic, rod-shaped, fermentative bacteria ( Enterobacteriaceae, Pasteurellaceae, Vibrionaceae) by a probabilistic method, in a computer, are given. The identification rate on the matrix was 89.2%. Many of the strains were atypical and had caused difficulty in identification in medical diagnostic laboratories. The results are given for each taxon by genus and species. I N T R O D U C T I O NA computer-assisted conditional probability method for the identification of enterobacteria was first described by Dybowski & Franklin (1968) and Lapage et al. (1970) used a similar scheme to successfully identify up to 80% of 279 freshly isolated strains. Later, Bascomb et al. (1973) published a matrix for the identification of Gram-negative rods of clinical importance and discussed its use in the identification of 1079 reference strains; the general aspects of probabilistic identification and the mathematical model used were described by Lapage et al. (1973) and Willcox et al. (1973), respectively. This latter matrix was then used as the basis for an identification service in our laboratory, the methods for which were reviewed by Willcox et al. (1980). In the operation of the identification service, the test results obtained for strains submitted for identification were accumulated by computer. These results were then sorted by taxon and printed in the form of summaries, as described by Holmes & Hill (1985). From these summarized results a revised matrix was derived for the fermentative organisms and, following evaluation, this matrix is now in current use for the routine identification service.In this paper we present the results obtained in the identification of 933 strains of bacteria belonging to 110 taxa in the revised probability matrix. METHODS Overallprocedure.A matrix was constructed which gave the probability of a strain of any given taxon yielding a positive result in each of the chosen tests (Table 1). Individual strains were then identified on the basis of these results.Taxa. Of the taxa chosen for the matrix (Table I), the majority gave a fermentative result in the oxidation/fermentation (O/F test) of Hugh & Leifson (1953). A few non-fermentative taxa were also included; these were taxa that produce acid from glucose in peptone/water/sugar media and that may possess other characteristics by which they may be confused with fermentative organisms.Although the range of taxa was selected primarily to include those of known medical importance and those likely to occur in medical specimens, efforts were made to include as many recently described species as possible, so as to facilitate recognition of the latter should they occur in human clinical or veterinary material. Particular attention was paid to ensure inclusion of all Enterobacteriaceae taxa described in Bergeys Manual of Systematic Bacteriology (Brenner, 1984). The majority of the taxa are recognized species, genera or subgenera. Some are t Present address: Gibco-Sensititre, Imberhorne La...