Examination of indigenous microbiota and survival of Escherichia coli 0157 and Salmonella in a paper milling environment.
OBJECTIVE
A public beach was frequently cited for health advisories because of high Escherichia coli levels, the source suspected to be a paper mill located upstream. This investigation sought to confirm whether or not the paper mill was the pollution source, and to characterize the risk to recreational bathers imposed by the source.


RESULTS
Quantification of E. coli in river water collected at incremental distances showed that paper mill effluent caused elevated E. coli levels in beach samples. Samples collected throughout the mill were variably positive for heterotrophic bacteria, total coliforms and E. coli, but negative for pathogenic E. coli O157 and Salmonella. Escherichia coli O157 or Salmonella spiked into mill samples (4.2 log(10) or 5.6 log(10) CFU per 100 ml, respectively) fell below detection levels within 14-24 h in raw (unaltered) samples, while in heat-sterilized replicates, the counts remained at initial levels or increased over 36 h.


CONCLUSIONS
Pathogenic E. coli O157 and Salmonella were not isolated from paper mill samples. The absence of native bacteria allowed the survival of pathogens, while their presence accelerated pathogen decline.


CONCLUSIONS
The co-existence of paper mill and swimming beach may be reasonable for now in spite of the limitations of an E. coli-based assay for beach water.
Degnan
A J
AJ
Wisconsin State Laboratory of Hygiene, University of Wisconsin-Madison, Madison, WI 53718, USA. degnanaj@mail.slh.wisc.edu
D000898:Antibiosis; D001493:Bathing Beaches; D015169:Colony Count, Microbial; D004783:Environmental Microbiology; D019453:Escherichia coli O157 / Q000302:isolation & purification* / Q000502:physiology; D005618:Fresh Water; D006801:Humans; D007218:Industrial Microbiology; D007220:Industrial Waste; D050296:Microbial Viability; D010209:Paper; D012475:Salmonella / Q000302:isolation & purification* / Q000502:physiology; D013242:Sterilization; D014934:Wood
D007220:Industrial Waste