TABLE 1.
Advantages and disadvantages of current methods used for microbial source tracking
| Method | Advantage(s) | Disadvantage(s) |
|---|---|---|
| Fecal coliform/fecal streptococous ratio | Easy to perform; may be useful for recent contamination | Variable survival rates of fecal streptococci can alter ratio |
| Bifidobacterium sp. | Sorbitol fermenters may be human specific | Low numbers present in environment; variable survival rates; culture methods not well-defined |
| B. fragilis HSP40 bacteriophage | Very human specific; easy to perform | Not present in sewage in some areas |
| F+ RNA bacteriophage | Groups are well-correlated with source; easy to perform | Unreliable in marine and tropical waters due to variable survival rates |
| Human enteric virus | Human specific; Direct monitoring for pathogen circumvents need to use indicators | Low numbers in environment; labor-intensive; more sensitive methods needed |
| MAR | Rapid; can be used to discriminate isolates from multiple animal sources | Requires reference database; may be geographically specific; isolates that show no antibiotic resistance cannot be typed |
| PFGE | Extremely sensitive to minute genetic differences | May be too sensitive to broadly discriminate for source tracking |
| BOX-PCR | Rapid; easy to perform | Reproducibility a concern; reference database required; may be geographically specific |
| Ribotyping | Highly reproducible; some methods useful for classifying isolates from multiple sources | Labor-intensive; reference database required; may be geographically specific; variations in methodology exist |
| Bacteroides-Prevotella molecular marker | Does not require culturing of organism; PCR method is rapid, easy to perform | Little is known about survival and distribution in water systems; currently not applicable to all animals |
| Caffeine | Useful for assessing impact from human sewage | Minute quantities in the environment make sensitivity an issue; requires expensive analyses |
| Fecal sterols and/or stanols | Some sterols/stanols have greater specificity for humans and/or animals | Present naturally in sediments; requires expensive analyses; Low prevalence makes sensitivity an issue |