Modification of kanamycin-esculin-azide agar to improve selectivity in the enumeration of fecal streptococci from water samples

Abstract

Kanamycin-esculin-azide agar was modified by increasing the concentration of sodium azide to 0.4 g liter ؊1 and replacing kanamycin sulfate with 5 mg of oxolinic acid liter ؊1. The modification, named oxolinic acidesculin-azide (OAA) agar, was compared with Slanetz-Bartley and KF agars by using drinking water and seawater samples. The OAA agar showed higher specificity, selectivity, and recovery efficiencies than those obtained by using the other media. In addition, no confirmation of typical colonies was needed when OAA agar was used, which significantly shortens the time of sample processing and increases the accuracy of the method.

Discriminant analysis of antibiotic resistance patterns in fecal streptococci, a method to differentiate human and animal sources of fecal pollution in natural waters

“…All tested isolates were gram-positive cocci, and the vast majority of them could grow at 45ЊC and in the presence of 6.5% NaCl ( Table 1). Most of these organisms can be classified as fecal streptococci (1,2).…”

Incidence of faecal streptococci as an indicator of sanitation in ice‐cream and frozen vegetables

“…Greater resistance of faecal streptococci, when compared with classical indicators of coliform bacteria, under unfavourable conditions such as drying and freezing has led to an increasing tendency to include faecal streptococci in microbiological criteria as an indicator of direct faecal contamination or plant sanitation in waters and various food products including ice‐cream and different frozen foods (El‐Zanfaly et al ., 1989; El‐Zanfaly & Shaban, 1991; Shapton & Shapton, 1991; Jay, 1992; Knudtson & Hartman, 1993; Audicana et al ., 1995; IFST, 1997; Temiz, 1999). Although faecal streptococci are widely used as faecal indicators, their acceptance as universal indicators of faecal pollution still presents some limitations such as the lack of standardized methodology for their selective enumeration and the taxonomic and ecological heterogeneity.…”

“…(1961) reported that the levels of faecal streptococci were higher than coliforms in frozen sea foods, thus favouring the faecal streptococci as better indicators of contamination in such foods. The occurrence of coliforms, faecal coliforms and faecal streptococci as an indicator of either direct faecal contamination or plant sanitation have been studied by others in frozen vegetables (Burton; cited by Insalata et al ., 1969), water (El‐Zanfaly et al ., 1989; El‐Zanfaly, 1991; El‐Zanfaly & Shaban, 1991; Audicana et al ., 1995), dehydrated vegetables (Clark et al ., 1966), frozen foods (Insalata et al ., 1969), skimmed milk powder (Neaves et al ., 1988) and sea foods (Raj et al ., 1961); and faecal streptococci have been proposed as an indicator of faecal contamination in waters (Cabelli et al ., 1982; Fattal et al ., 1986; Ferley et al ., 1989; Jay, 1992); both drinking and mineral waters (IFST, 1997); ready cooked served cold foods, frozen vegetables, sea foods bivalve (shellfish) cleaned and ice‐cream (Shapton & Shapton, 1991).…”

Oligonucleotide microarray for identification ofEnterococcusspecies

“…The protein denaturation step was repeated twice, and the retrieved cells resuspended in 200 μl PBS. Half of the cells were plated on oxolinic acid‐esculin‐azide enterococci selective agar [26], whereas the other half was used for extraction of nucleic acids.…”