[Rat-bite fever--two cases of infection with Streptobacillus moniliformis within two months]

Medical history and clinical findings | Two cases of the rarely diagnosed Streptobacillus moniliformis infection (rat bite or haverhill fever) emerged within two months in Stuttgart. The first patient presented with typical symptoms, i.e., fever and arthralgia. The second patient, however, was afebrile with severe back pain and fatigue as only symptoms. None of the patients reported rat bites or other animal contacts. Examinations | Physical examination did not reveal any focus of infection in the first patient. Further examinations could not be completed. Suspected diagnosis was therefore "unclear, most likely viral infection". In the case of the second patient, ultrasound revealed an engorged right kidney and urinary obstruction. Upon concomitant detection of Escherichia coli in the urine, pyelonephritis was suspected. Laboratory parameters were not indicative in neither case. Detection of the infectious agents was accomplished by blood cultures and subsequent identification by mass spectrometry, albeit after discharge of the patients. Treatment and course | The first patient left the hospital against the doctors' advice the day after his admission. The second patient improved under ciprofloxacin and metamizole therapy and was discharged after five days with the recommendation to continue the antibiotic therapy. Conclusion | Cases of rat bite or haverhill fever are difficult to diagnose when no rat bites are recognized. Seroprevalence data of S. moniliformis infection would be desirable to estimate how often atypical or subclinical cases of this potentially lethal infection go undiagnosed.