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The Journal of the Japanese Society for Clinical Microbiology |
Biblioraphy Information
| ArticleTitle |
Acute pyelonephritis in a pediatric patient caused by thymidine-requiring Small Colony Variant of Escherichia coli |
| Language |
J |
| AuthorList |
Naoko Takahashi1), Toru Higuchi2), Kenta Ito2), Noboru Hayakawa1) |
| Affiliation |
1) Department of Clinical Laboratory, Aichi Children's Health and Medical Center
2) Department of General Pediatrics, Aichi Children's Health and Medical Center |
| Publication |
J.J.C.M.: 32 (3), 166-172, 2022 |
| Received |
November 2, 2021 |
| Accepted |
March 28, 2022 |
| Abstract |
A Small Colony Variant (SCV) of Escherichia coli was isolated from the urine of a pediatric patient with acute pyelonephritis. Gram-negative rods phagocytosed by neutrophils were identified on urine Gram stain. The patient was initiated on cefotaxime. The urine culture yielded small, flat colonies formed on sheep blood agar and MacConkey agar after 18 hours of incubation. The isolate was inoculated into a test panel for Enterobacterales and was examined using a microbial identification and susceptibility system. However, the isolate did not grow in the controlled medium, invalidating the test. The isolate was suspected to be an SCV. Therefore, it was diluted with the broth for Haemophilus spp. susceptibility testing and inoculated into the same panel. Growth was observed, and the isolate was identified as E. coli. The MIC of ampicillin (ABPC) was 8 μg/mL or less. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) also identified the isolate as E. coli. Thus, the patient treatment was de-escalated to ABPC. Additional testing showed that the isolate required thymidine for growth. The use of nutrient-rich media may narrow down the MIC range for SCVs to be reported as a reference value. MALDI-TOF MS may be useful for the rapid identification of SCVs. |
| Keywords |
Escherichia coli, Small Colony Variant (SCV) |
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