Resistotyping ofProteus mirabilisand a comparison with other methods of typing

Abstract

SYNOPSIS Resistotyping of P. mirabilis using 10 compounds is reported. The method was tested for reproducibility and specificity and results were compared with those obtained by serological, bacteriophage, and proticine typing methods and the Dienes test. The possible relationship between resistance to the chemicals used in the test and antibiotics was also studied.The method was found to be simple, reproducible, show good specificity, and compare favourably with other typing methods. No linkage between resistance to the chemicals and antibiotic resistance was detected.Proteus mirabilis is a normal commensal of the intestinal tract and can cause bacteraemia and infection of the urinary tract, of wounds, of burns, and of the meninges. The incidence of severe infections due to this organism appears to be increasing (Finland, 1960;Lewis and Feckety, 1969) and outbreaks of infection are occasionally reported (Adler, Burke, Martin, and Finland, 1971 Received for publication 20 March 1974. by the Dienes test (Skirrow, 1969) were selected initially as control strains from a number of routine laboratory isolates. These strains proved to be satisfactory and were used as controls in all the tests. Eighty-nine strains of unknown type isolated from a routine laboratory and 115 other strains of known phage, serological, and proticine type were resistotyped. Strains isolated from the faeces and urine of 18 patients and the umbilicus and faeces of two babies were also typed. MEDIATryptose (Difco)-agar with 0 5 % sodium taurocholate was made up in Tris buffer (BDH) at pH 7-6 and used in all tests. Tryptose agar was used at a concentration 10% higher than recommended by the manufacturer. Triphenyl tetrazolium chloride (TTC) 0-2 % was used as an indicator and was added to the medium with the required chemical. Peptone water (Oxoid) was used for growing strains before inoculation of plates.

A highly discriminatory multi-typing scheme for Proteus mirabilis and Proteus vulgaris

“…are needed. Several techniques have been described (Tracy and Thomson, 1972;Kashbur, George and Ayliffe, 1974;Schmidt and Jeffries, 1974), but few have come into widespread use. Serotyping of Proteus spp.…”

An evaluation of two methods of bacteriocine typing of organisms of the genus Proteus.

“…The same 33 isolates had been typed using the Cradock-Watson method on two occasions with identical results, giving nine types with two untypable isolates (George, unpublished results; CPHL, unpublished results). In (Kashbur et al, 1974), and by thX resistogram technique the 33 isolates had been shown to consist of 28 different strains (Kashbur et al, 1974). The Al-Jumaili system demonstrated 18 proteocine sensitive patterns with no untypable isolates (table VII).…”

Comparison of different media for bacteriocine typing of Proteus mirabilis.

“…An alternative scheme based on the sensitivity of strains to high-titre extracts is being developed by the author, but as yet a panel of extracts which enables differentiation into a large number of strains with few or no untypable strains is not available. The improvement in the present typing method using bacteriocine agar should encourage its more frequent application, but the use of two typing methods is preferable, as it allows a greater proportion of strains to be typed (Kashbur, George, and Ayliffe, 1974).…”