Clients often ask about the preferred method of transporting urine samples to the laboratory for culture, and the effect of transport time and storage temperature on the viability of organisms.

To address these questions, the following study was performed: Urine samples with pyuria (n = 18) submitted in RTT to Antech's Houston laboratory were divided into several aliquots. One aliquot was inoculated immediately onto blood/MacConkey agar and cultured aerobically for 72 hours in the Houston laboratory. The urine aliquots were also placed into 3 tubes: RTT, grey top urine culture tube (Transport Kit, KT), and Copan Swab (CS) for transport to Antech's Irvine laboratory, where they were stored at 4-8º C and at room temperature (RT). They were next inoculated onto blood/MacConkey agar for aerobic culture and examined after 24, 48 and 72 hours.

Fourteen urine samples cultured positive for bacteria and 4 were negative. There was no observed effect of storage time, storage temperature, or type of storage tube on these culture results, or on the amount of bacterial growth (light, moderate or heavy).

Conclusion: Based on these findings, we consider RTT to be the preferred collection tube for urine culture. Routine transport time does not influence urine culture results.

Blood samples from ferrets are usually of small volume, and therefore dilution may be necessary to run chemistry tests. However, a discrepancy was observed in creatinine concentrations measured in undiluted versus diluted samples. To investigate this observation, creatinine concentrations were measured in undiluted and diluted (1:2 with distilled water) serum or plasma from 10 ferrets. Albumin, AST, BUN, CPK, total bilirubin and total protein were similarly compared.

Creatinine concentrations were significantly lower (mean difference 28%; p < 0.05) when determined on diluted serum or plasma. There was no significant effect of sample dilution on the other analytes tested.

Conclusion: Creatinine concentrations may be falsely decreased when ferret samples require dilution for analysis. To minimize our need to dilute ferret plasma samples, please try to fill the green Microtainer® specimen tubes to the top line.