Preliminary Survey of Antibiotic-Resistant Fecal Indicator
Bacteria and Pathogenic Escherichia coli from River-Water Samples Collected in Oakland County, Mich.,
A preliminary study was done in Oakland County, Michigan,
to determine the concentration of fecal indicator bacteria (fecal coliform
bacteria and enterococci), antibiotic resistance patterns of these two groups,
and the presence of potentially pathogenic Escherichia
coli (E. coli).
For selected sites, specific members of these groups [E. coli, Enterococcus faecium (E. faecium) and Enterococcus faecalis (E. faecalis)] were isolated and tested
for levels of resistance to specific antibiotics used to treat human infections
by pathogens in these groups and for their potential to transfer these
resistances. In addition, water samples from all sites were tested for
indicators of potentially pathogenic E.
coli by three assays: a growth-based assay for
sorbitol-negative E. coli,
an immunological assay for E. coli
O157, and a molecular assay for three virulence and two serotype genes. Samples
were also collected from two non-urbanized sites outside of Oakland County.
Results from the urbanized Oakland
County area were compared
to those from these two non-urbanized sites.
Fecal indicator bacteria concentrations exceeded State
of Michigan recreational water-quality
standards and (or) recommended U.S. Environmental Protection Agency (USEPA)
standards in samples from all but two Oakland County
sites. Multiple-antibiotic-resistant fecal coliform bacteria were found at all
sites, including two reference sites from outside the county. Two sites (Stony
Creek and Paint Creek) yielded fecal coliform isolates resistant to all tested
antibiotics. Patterns indicative of extended-spectrum- -lactamase
(ESBL)-producing fecal coliform bacteria were found at eight sites in Oakland County
and E. coli resistant to
clinically significant antibiotics were recovered from the River Rouge, Clinton River, and Paint Creek.
Vancomycin-resistant presumptive enterococci were found at six sites in Oakland County and were not found at the
reference sites. Evidence of acquired antibiotic resistances was detected in bacteria
from multiple sites in Oakland
County but not detected
in bacteria from the reference sites. Integrons capable of transferring
resistance were detected in isolates from the River Rouge and Clinton River.
E. faecium and identified
in samples collected from Kearsley Creek and Evans Ditch were resistant to high
levels of vancomycin and carried transferable genes responsible for resistance.
Several sites in Oakland County
had indicators of pathogenic E. coli
in August and (or) September 2003. Two samples from the Clinton River
in August tested positive for all three E.
coli O157 tests. Both the August and September samples from one
River Rouge site were positive for the immunological and molecular assay for E. coli O157. A combination of virulence
genes commonly associated with human illness was detected at five sites in
August and seven sites in September. Antibiotic-resistance profiles of clinical
concern along with genes capable of transferring the resistance were found at
several sites throughout Oakland
County; samples from many
of these sites also contained potentially pathogenic E. coli.
L.R., Duris, J.W., Aichele, S.S., 2005, Preliminary Survey of
Antibiotic-Resistant Fecal Indicator Bacteria and Pathogenic Escherichia coli
from River-Water Samples Collected in Oakland County, Mich., 2003: Date Posted:
July 27, 2005, U.S. Geological Survey Scientific Investigations Report
2005-5058, 34 p.
Make all Michigan's waters fishable and swimmable. –RJ.