Table 6.
Alternatives to standard equipment and methods.
| Standard 1 | Alternative 1 | Advantages | Limitations |
|---|---|---|---|
| Laboratory Incubator ($$$) | Ambient incubation (-) | Possibly acceptable in tropical climates [20] or potentially indoors | Recoveries for injured bacteria may be poor; increased and poorly defined incubation time; not applicable everywhere |
| Low-cost electric incubators ($–$$) e.g., egg incubator | Good temperature control | Reliant on electricity, may not be available for higher temperatures (44.5°C for TTC) | |
| Body incubation (-) | Readily available | Acceptability, health and safety issues and limited number of tests | |
| Phase change incubator ($) | Good temperature control, only requires hot water | Requires heat source, can be bulky, particularly for many tests | |
| De-ioniser ($$$) | Boiled water (-) | Readily available | May not inactivate all organisms; can concentrate chemical contaminants need to run blanks |
| Steam distiller ($$) | Produces very pure water | Requires high-voltage and power; requires running water; fragile | |
| Autoclave (see below) | May be available or has dual use (see below) | Turbid waters may not provide suitable dilution water, especially for membrane filtration | |
| Membrane Filtration assembly & vacuum ($$$) | Portable MF assembly, including hand pump or MIT D-lab kit ($–$$) | Manual, portable | Time consuming procedure Separate incubator required |
| Autoclave ($$) | Portable autoclave ($) | Portable | Requires heat source |
| Pressure cooker ($) | Independent of electricity | Requires heat source | |
| Bleach or disinfectant ($) | Readily available, good for disinfecting waste | Handling of cultures; care must be taken in reusing components to prevent false negatives due to residual disinfectant | |
| Refrigerator or freezer ($$) | Storage at room temperature (-) | Independence from electricity | Shelf-life unclear for many media, particularly hydrated media; samples cannot be retained for subsequent analysis |
| Sample transport on ice | Ambient temperature transport | Simple | Potential population increase or die-off of bacteria |
| Insulated box (with cool water if available) | May be better than ambient | Change in bacterial population unknown, likely to be better than ambient |
1 Approximate costs are: Free (-), $ (1–100), $$ (100–1,000), $$$(1,000–10,000).