Chlortetracycline and the macrolide tylosin were identified as commonly used antimicrobials for growth promotion and prophylaxis in swine production. Resistance to these antimicrobials was measured throughout the waste treatment processes at five swine farms by culture-based and molecular methods. Conventional farm samples had the highest levels of resistance with both culture-based and molecul...

The important role of commensal flora as a natural reservoir of bacterial resistance is now well established. However, whether the behavior of each commensal flora is similar to that of other floras in terms of rates of carriage and risk factors for bacterial resistance is unknown. During a 6-month period, we prospectively investigated colonization with fluoroquinolone-resistant bacteria in the...

In recent years, publications from this laboratory (Snyder and Lichstein, 1940; Lichstein and Snyder, 1941; Lichstein, 1941) have indicated the value of sodium azide (NaN3) as an aid in the isolation of streptococci from clinical material containing "spreaders" and other interfering gram-negative organisms. The use of blood-infusion agar containing 0.02 per cent sodium azide for the cultivation...

The group Q streptococci possess unique serological and physiological characteristics which differentiate them from established enterococci. The group Q antigen was not demonstrable in all strains; however, all possessed the group D antigen. All group Q strains were physiologically similar regardless of whether or not they possessed the group Q antigen. These strains differed from the establish...

Over the past 6 years, a revised classification of the streptococci and enterococci, based primarily on molecular techniques such as 16S rRNA sequencing and DNA-DNA hybridization, emerged. However, little attention was placed on routine physiological tests that could be used in food and clinical laboratories to differentiate between species of a new genus, Enterococcus, and fecal Streptococcus ...

Estimates of NH4+-and NO2-oxidizers in samples from four activated sludge plants treating mainly domestic sewage were obtained using a most-probable-number (MPN) technique. Ranges of concentrations per milliliter of each, respectively, were 1,010 to 3,880 and 79 to 145 in settled sewages, 32 to 7,420 and 2 to 1,010 in secondary effluents, and less than 0.1 to 622 and 0.1 to 70 in chlorinated se...

Extended survival of fecal bacteria in sediment can obscure the source and extent of fecal contamination in agricultural settings. The variability in fecal coliform/fecal streptococci (FC/FS) ratios with time and discrepancies between observable fecal sources and measured FC/ FS ratios in shallow surface water from agricultural watersheds may be explained by examining FC and FS mortality rates ...