Evaluation of an alternative method for the enumeration and confirmation of Clostridium perfringens from treated and untreated sewages.
OBJECTIVE
Clostridium perfringens is recommended as a suitable indicator bacterium for human enteric viruses, Giardia cysts and Cryptosporidium oocysts in finished water and in the assessment and evaluation of water treatment. Several agars and confirmation procedures were evaluated in parallel with the Australian/New Zealand Standard (AS/NZ) Method for the enumeration of Cl. perfringens from treated and untreated sewage samples.


RESULTS
The current AS/NZ method utilizes tryptose sulfite cycloserine agar (TSC), lactose gelatin medium (LG) and nitrate motility medium (NM) at an incubation temperature of 37 degrees C. Sixty treated and untreated sewage samples were used to evaluate TSC agar, membrane Cl. perfringens agar (mCP), Perfringens agar (OPSP) and Perfringens agar with 4-methylumbelliferyl phosphate (OPSP-MUP) for enumeration of Clostridium. An incubation temperature of 44 degrees C for 24 h was used for comparison. Confirmation procedures were also evaluated using 103 isolates and included LG and NM, ortho-nitrophenyl-beta-D-galactopyranoside (ONPG) with MUP (ONPG-MUP) and phosphatase reagent (PR). OPSP compared favourably with TSC agar. One false negative result was obtained from each of the LG/NM and ONPG-MUP procedures. No false results were obtained using the PR confirmation procedure.


CONCLUSIONS
OPSP agar and PR were determined as suitable replacements for the AS/NZ Standard procedure with no interference from spreading organisms.


CONCLUSIONS
This is a simple and rapid method for isolating and enumerating Cl. perfringens from sewage samples and confirmed results can be reported more quickly due to shorter analytical turnaround times.
Wohlsen
T
T
Public Health Microbiology, Queensland Health Scientific Services, Queensland, Australia. tracy_wohlsen@health.qld.gov.au
Bayliss
J
J
Gray
B
B
Bates
J
J
Katouli
M
M
D003016:Clostridium perfringens / Q000254:growth & development / Q000302:isolation & purification*; D015169:Colony Count, Microbial / Q000379:methods*; D003470:Culture Media / Q000737:chemistry; D010744:Phosphoric Monoester Hydrolases / Q000032:analysis; D012680:Sensitivity and Specificity; D012722:Sewage / Q000382:microbiology*; D013696:Temperature; D018508:Water Purification / Q000379:methods; D001616:beta-Galactosidase / Q000032:analysis
D003470:Culture Media; D012722:Sewage; D010744:Phosphoric Monoester Hydrolases; D001616:beta-Galactosidase