Rat Bite Fever Caused by Streptobacillus moniliformis in a Cirrhotic Patient Initially Presenting with Various Systemic Features Resembling Henoch-Schönlein Purpura

Abstract

We herein report the case of a 61-year-old Japanese cirrhotic patient who developed rat bite fever (RBF) and whose first presentation was serious clinical features mimicking those of Henoch-Schönlein purpura (HSP). In addition to the critical clinical conditions, since the histopathology from purpuric skin eruptions was not inconsistent with that of HSP, therapy with prednisolone was promptly started in order to prevent his death. However, initial blood culture on admission yielded a small and slow-growing bacterial growth, which was gradually revealed by further subculture to be a peculiar bacterium, Streptobacillus moniliformis, leading to a definitive diagnosis of RBF. After the immediate cessation of prednisolone, the patient was treated with a more appropriate antibiotic and consequently made a full recovery. An immunocompromised condition with seriously decompensated liver cirrhosis together with moderately severe chronic kidney disease (CKD) in this patient probably exacerbated the severity of the disease.

Keywords: Henoch-Schönlein purpura (HSP); Streptobacillus moniliformis; chronic kidney disease (CKD); liver cirrhosis (LC); rat bite fever (RBF).

Figure 1.

Dusky-red purpuric skin eruptions were obvious over the patient’s palms (a) and soles (b).

Figure 2.

Histopathological findings of a specimen obtained from eruptions on the left knee demonstrated unspecific vasculitis; extravasation of neutrophils and leukocytoclastic vasculitis were noted throughout the dermis (a, b). (a) Hematoxylin and Eosin (H&E) staining 40×, (b) H&E staining 400×.

Figure 3.

Small and slow-growing bacteria were detected in the anaerobic culture bottle after 33 h of incubation (a). Gram stain (1,000×). After further subculture by exchanging media, some colonies were visualized on blood agar (b). On the sixth hospital day, highly pleomorphic filamentous Gram-negative bacilli were isolated (c). Gram stain (1,000×).

Figure 4.

The clinical course in the present case. PSL: prednisolone, CRP: C-reactive protein, Cre: creatinine

Figure 5.

The underlined nucleotide sequence was identical to that of the R. rattus-derived strain.