Effect of UV light disinfection on antibiotic-resistant coliforms in wastewater effluents.
EPA Research document. (1981)
Mark Meckes, EPA

In 1959, Watanabe (31) discovered that some Escherichia coli strains could transfer antibiotic
resistance to antibiotic-sensitive strains of Shigella spp. Subsequent research has demonstrated
that bacteria carrying transmissible R-factors are responsible for the spread of multiple antibiotic
resistance among members of the Enterobacteriaceae (such as E. coli, Salmonella typhi,
and Shigella dysenteriae) Aeromonas and Yersinia species (4), Pseudomonas aeruginosa (21),
and Vibrio cholerae (34).

The percentage of coliforms transferring resistance to the antibiotic-sensitive strain varied.

Several researchers have pointed out that wastewater, treated or untreated, is a primary
contributor of bacteria to the aquatic ecosystem (12, 16, 17, 20, 27, 29). Studies have been
conducted which demonstrate that significant numbers of multiple drug-resistant coliforms occur
in rivers (17), bays (9), bathing beaches (28), and coastal canals (13). Waters contaminated by
bacteria capable of transferring drug resistance are of great concern since there is the potential
for transfer of antibiotic resistance to a pathogenic species..

The mean percentage of all total coliform isolates capable of transferring all or part of their
antibiotic resistance (46%) was identical to that observed by Fontaine and Hoadley (10) for drug
resistant fecal coliforms isolated from undisinfected municipal wastewaters. Similarly, Sturtevant
and Feary (29) reported that 43% of the drug-resistant total coliforms, isolated from
undisinfected municipal wastewaters (before and after biological trickling-filter treatment), were
capable of transferring resistance to a sensitive strain of E. coli.

It is evident from this work as well as from the work of others (10, 13-15, 29) that antibiotic
resistant coliforms are entering the aquatic environment via treated municipal wastewater

This work demonstrates that UV light disinfection can effectively reduce the number of total
coliforms both sensitive and resistant to antibiotics in an activated sludge effluent. This
work also points out that there is a significant increase in the percentage of the surviving total
coliform population resistant to tetracycline and chloramphenicol after UV irradiation.

This study concerned itself with UV disinfection. There is little information available which
discusses the effect of other disinfectants on antibiotic-resistant organisms. Additional
investigations should be conducted to determine what effect other wastewater disinfectants, such
as chlorine or ozone, may have on the antibiotic resistant fraction of the bacterial population.
There is an additional need to determine the sanitary significance of the results of
such investigations.

Multi-drug resistant bacteria (MDRB) and --- Sludge—
Those most affected are the immunocompromised, elderly, and those with barrier disruptions to
the skin or mucosal membranes. In the last case it may be merely from beach sand scratching the
skin at the waistline of bathing suits or under wet suites, or swallowing contaminated water.

Based on wastewater industry dogma and standards, released effluent, its use in irrigation salad
crops, and the land application of sewage sludge are benign and beneficial activities. If however,
one reviews the current medical and scientific literature, a different picture emerges, one that
raises serious questions about the benevolence of this activity and efficacy of the underlying
standards. Thus, the issue takes on aspects of a political and not a scientific argument.

Sources of Pathogenic Microorganisms and Their Fate during Land Application of Wastes

Antibiotic resistant bacteria and gene transfer.

Microbiol Immunol. 2001;45(5):383-6.
Resistance to antibiotics in injured coliforms isolated from drinking water.

Córdoba MA, Roccia IL, De Luca MM, Pezzani BC, Basualdo JA.

Cátedra de Microbiología y Parasitología, Facultad de Ciencias Médicas, Universidad Nacional
de La Plata, Argentina, Republica Argentina.

We studied the antibiotic sensitivity of injured coliforms isolated from drinking water of La Plata,
Argentina. The antibiotic sensitivity test by the agar diffusion method were proved in: Klebsiella
oxytoca (14 strains), Enterobacter aerogenes (4 strains) and Enterobacter cloacae genomic
group 3 (14 strains). We found that while these impaired total coliforms were sensitive to
piperacillin-tazobactam (TAZ), netilmicin (NTL), ofloxacin (OFLX), and norfloxacin (NFLX) (100%),
they had resistant to aminopenicillin-sulbactam (AMS) and nitrofurantoin (NIT) (100%). The
resistance to antibiotics demonstrated in these strains would point to the need to promote a
rational and judicious use of antimicrobial agents while at the same time implementing a program
of active vigilance aimed at ensuring the highest quality of drinking water throughout the system.