Isolation ofShigella sonneiby fluid media

Abstract

Selenite F broth prepared in the laboratory from single ingredients was found to be significantly more efficient than nutrient broth in the isolation of Shigella sonnei from human faeces. It was more efficient than direct plating on deoxycholate citrate agar for diagnosisng Sonne dysentery in a local outbreak. The difference was significant. There was, however, no significant advantage for enrichment over direct plating when stools posted from Briston to Cardiff were examined. Laboratory prepared selenite F broth was preferable to the same medium purchased commercially from two different firms. The product of one frim was significantly better than that of the other. Two methods of sterilization of laboratory prepared selenite F broth were studied. Seitz filtered selenite was less inhibitory to the growth of samll numbers of Shigella sonnei. Sterilization by heating in free steam for periods of 15 min and over impaired the ability of selenite F broth to allow multiplication of small numbers of Shigella sonnei.

Quality Control of Solid Culture Media: A Comparison of the Classic and the So‐called Ecometric Technique

“…In addition extrinsic factors during incubation, particularly temperature, temperature fluctuations and a,, p02 and pC0z of the environment in which incubation takes place can dramatically influence the performance of a given medium. 1974;Harvey et al 1975;Fagerberg et al 1976;Nicholls et al 1976;Papadakis et al 1976;Price 1976;Staat 1976;Hanna et al 1977 should, therefore, be regular quality monitoring of all types of culture media (Mossel 1971;Vera 1971;Prier et al 1975;Stokes 1979). These include: (i) n u~t i o n a l dependence of the organisms in~ulated on or in the m e d i~; (ii) ~~g o n i s t i c ph~nomena, depending strongly on the so-called background association, present in the specimen (Mossel et al 1978~) and hence determined by the type and condition of the material under ~nv~stigation; and (iii) syner~sm between components of the microbial a~~i a t i o n of the specimen, as, for example, observed in sateIlite growth ( C h u r c~a n & Kahn 1921; Moon & Reinbold 1976).…”

“…Many more observations demonstrate deficiencies of selective media, which rely on delicate equilibria between productive and selective mechanisms of various sorts (Kligler 1918;Banwart & Ayres 1953;Burman 1955;Miller & Banwart 1965;Read & Reyes 1968;Taylor & Schelhart 1968;Wilson et al 1970;Reusze 1971;McCormack et al 1974;Moats & Kinner 1974;Mossel et at. 1974;Harvey et al 1975;Fagerberg et al 1976;Nicholls et al 1976;Papadakis et al 1976;Price 1976;Staat 1976;Hanna et al 1977 should, therefore, be regular quality monitoring of all types of culture media (Mossel 1971;Vera 1971;Prier et al 1975;Stokes 1979).…”

Effect of stool storage at room temperature on salmonella isolation from faeces

“…We have not had the opportunity of testing strontium selenite broth (Iveson & Mackay-Scollay, 1969). Selenite F is also of value in the isolation of Shigella sonnei from stools (Price, 1976). From Table 2, however, it is possible that laboratory prepared Muller-Kauffmann tetrathionate might be useful in the examination of faecal samples arriving at the laboratory after postal delays.…”

Frequency of failure to isolate Shigella spp. by the direct plating technique and improvement of isolation by enrichment in selenite broth

“…to eliminate other intestinal bacteria. Price et al [7] reported, however, that S. sonnei could be isolated on agar plates after enrichment in selenite broth. We also sometimes found Shigella spp.…”

“…An enrichment broth for Shigella spp. has been reported [7,8,[15][16][17] ; however, further development of more effective methods for the isolation of Shigella spp. is needed [11].…”