Selective action of inhibitors used in different culture media on the competitive microflora of Salmonella

Abstract

The action of 12 inhibitors employed in the culture media used to detect the presence of Salmonella in food on 24 bacterial strains including contaminating Gram-positive bacteria common in water and food, Gram-negative bacteria, especially Enterobacteriaceae and Pseudomonadaceae, which are components of the competitive microflora, and six Salmonella serotypes was tested. Two liquid culture media (AR 5 and AE 1) were used. Series of tubes containing increasing concentrations of each inhibitor were inoculated with the test strains and incubated at 37 degrees C until growth was verified spectrophotometrically (24-48 h). The results showed that the inhibitors were effective against the Gram-positive contaminating microflora. They did not preferentially inhibit the competitive microflora of Salmonella, chiefly Enterobacteriaceae, and were ineffective against the Pseudomonas strains, which can tolerate concentrations higher than those customarily employed in culture media.

Enumeration of Salmonella and Escherichia coli O157:H7 in ground beef, cattle carcass, hide and faecal samples using direct plating methods†

“…2006). One of the drawbacks encountered when this method is employed for the enumeration of a particular pathogen is that it relies on the enrichment of low numbers of target organisms, and the ensuing competition between the target organism to be enumerated and the background flora of the sample likely hinders pathogen detection (Arroyo and Arroyo 1995). Previous enumeration studies of beef carcass samples in our laboratory using traditional MPN methods were problematic and yielded inconsistent results (Barkocy‐Gallagher et al.…”

Multiplex-PCR and PCR-RFLP assays to monitor water quality against pathogenic bacteria

“…Third, many pathogenic organisms in the environment, although viable, are either difficult to culture because of their nutritional requirements, or are non-culturable (Byrd et al, 20 Nilsson et al, 21 Yokomaku et al 22 ). In addition, the use of selective media containing inhibitory compounds to eliminate background bacteria may also be inhibitory to environmentally stressed isolates (Arroyo and Arroyo 23 ). In contrast to the above, by PCR methods, samples containing the targeted pathogens and especially viable but non-culturable organisms can be detected within hours, instead of the days required in traditional biochemical methods (Palmer et al, 24 McDaniels et al 6 ).…”

La relación entre el nombre y la figua en los relieves hititas: una actualización

“…El relieve hitita de Taşçı B (FIGURA 10), en el que personaje masculino sostiene el símbolo bonus 2 y su nombre aparece inciso bajo el brazo -posición atípica en los relieves 16 -presenta la misma composición que varios sellos. Entre ellos se cuentan dos de la colección Borowski, de Walwi (sosteniendo bonus 2 , FIGURA 11) y Patiya 17 (sosteniendo el signo *442 invertido, «Heils-oder glückbringendes Zeichen» 18 , FIGURA 12).…”