TABLE 3.
Mixed-culture (i.e., two to three different types of pathogen) results for which CHROMagar and conventional plates failed to agree on interpretation
| Organisms | No. of occasions | Medium with correct interpretation | Description of inconsistency |
|---|---|---|---|
| Proteus sp. and Klebsiella oxytoca | 1 | Blood agar-MacConkey | Not detected on COa |
| Escherichia coli and Proteus sp. | 1 | Blood agar-MacConkey | Proteus not detected on COa |
| Escherichia coli and Klebsiella oxytoca | 1 | Blood agar-MacConkey | Escherichia coli not detected on COa |
| Leclercia sp. and Klebsiella oxytoca | 1 | Blood agar-MacConkey | Klebsiella oxytoca not detected on COa |
| Escherichia coli, Pseudomonas aeruginosa, and enterococci | 1 | CO | Escherichia coli not detected on BAPa |
| Escherichia coli and Proteus sp. | 1 | CO | Two morphotypes worked up on bench that turned out to be the same species on CO |
| Escherichia coli and Staphylococcus saprophyticus | 1 | CO | CFU of Escherichia coli was below threshold on BAPa |
| Klebsiella pneumoniae and Proteus mirabilis | 1 | CO | Reported as “mixed flora” by routine medium cultures |
| Enterobacter cloacae and viridans streptococci | 1 | CO | Two morphotypes of E. cloacae worked up on bench that turned out to be the same species on CO |
| S. aureus, Enterococcus sp., and group B streptococci | 1 | CO | Enterococcus sp. not detected on BAP |
| E. faecalis, S. aureus, and yeast sp. | 1 | CO | Enterococcus sp. not detected on BAP; lower CFU on conventional media, reported as “mixed flora” |
a
Most discrepancies were based on differences in CFU counts. Observations of urine plating by paratechnical personnel showed varying expertise, and this likely accounts for most of the discrepancies.