Rat bite fever as a presenting illness in a patient with AIDS

Septic arthritis complicating Streptobacillus moniliformis rat bite fever: a case report and review of its pathophysiology and diagnosis

Rat bite fever is characterized by a clinical triad of symptoms, fever, rash and arthritis. It is transmitted by rodents and mainly due to infection by Streptobacillus moniliformis, a fastidious bacterium carried by Rattus norvegicus. This case report presents the case of a patient who developed septic arthritis and fever after a wild rat bite, with subsequent isolation of S. moniliformis from the joint fluid. Upon reviewing 45 other published case reports of S. moniliformis osteoarticular infections following contact with either a rat or its secretions, it was firstly observed that the rat bite fever clinical triad was incomplete in over half of the cases, mainly because rash was infrequently observed among adult patients. Secondly, the clinical presentation of rat bite fever is quite non-specific and rodent exposure is not mentioned by patients in a third of cases upon admission. Altogether, diagnosing rat bite fever is a significant clinical challenge suggesting that it might be significantly underdiagnosed. In addition to these clinical aspects, no evidence was found supporting immunological mechanisms, as suggested in some literature. Instead, when excluding five improperly performed cultures, S. moniliformis was cultured in 25 reported cases and identified twice by direct PCR sequencing amounting to a detection rate of 90% (n = 27/30) on joint fluids. Cultures should be performed in medium containing yeast extract, complete peptic digest of animal tissue and at least 5% blood. Knowing that S. moniliformis is very sensitive to many antibiotics thereby making the culture negative, direct 16S rRNA gene sequencing on joint fluid is an alternative method in the case of clinical and cytological evidence of osteoarticular infections with sterile culture of joint fluid.

Rat bite fever in a patient with human immunodeficiency virus

The authors report the case of a 45-year-old male with history of human immunodeficiency virus who presented unresponsive and with injuries to his hands after spending a night on a lakeside beach. During his hospitalization, he developed a fever with arthralgias and was initially thought to have calcium pyrophosphate dihydrate crystal deposition disease before a diagnosis of Rat Bite Fever was ultimately discovered. He was successfully treated with six-weeks of ceftriaxone. The authors discuss the epidemiology, diagnosis, treatment, and prognosis of Rat Bite Fever.

Prevalence and Diversity of the Streptobacillus Rat-bite Fever Agent, in Three Invasive, Commensal Rattus Species from South Africa

Rat-bite fever is an over-looked, global zoonotic disease that has a mortality rate of up to 13%, if untreated. Historically, this rat-borne disease has been attributed to one of two causative agents, Streptobacillus moniliformis or Spirillum minus. Given the confirmed presence of multiple invasive Rattus host species, high rat densities in urban, informal human settlements and increasing reports of rat bites in South Africa, we undertook a retrospective assessment of Streptobacillus in rats sampled from 16 urban sites, in Gauteng, the smallest but most populous Province in South Africa. Using a multi-gene PCR-sequencing approach, we confirmed Streptobacillus presence in 50.9% of oral swabs from three rat species and the presence of two Streptobacillus species, viz.S. moniliformis and S. notomytis. The two members of the cryptic Rattus rattus species complex (R. rattus and R. tanezumi), which are morphologically indistinguishable from each other, had markedly different colonization rates. Whereas 48.6% of rats from this species complex were Streptobacillus-positive, only 32.3% of Rattus tanezumi were positive compared to 61.5% R. rattus. Rattus norvegicus had an intermediate prevalence of 55.6%. Phylogenetic analysis of four gene regions (16S rRNA, gyrB, groEL, recA) identified two discrete lineages; S. moniliformis occurred exclusively in R.norvegicus, and S. notomytis was restricted to the two members of the R. rattus species complex; this represents the first report of Streptobacillus in R. tanezumi. These results highlight a largely overlooked zoonotic threat posed by invasive rats and confirm the presence of two discrete and potentially host-specific Streptobacillus lineages in South Africa.

Rat bite fever caused by Streptobacillus moniliformis infection in a Chinese patient

BACKGROUND

Rat bite fever (RBF), a severe infectious disease, can result from transmission of the pathogen Streptobacillus moniliformis (S. moniliformis) by rat bite. RBF diagnosis can be overlooked.

CASE PRESENTATION

We present a case of RBF in a Chinese patient who was infected with S. moniliformis in mainland China. Meta-next generation sequencing (mNGS) was used to identify potential pathogens and detected S. moniliformis genome sequences in the pustular sample in less than 72 h. Then the diagnosis was validated by polymerase chain reaction analysis. Despite having severe RBF with complications, this 54-year-old male patient was successfully cured with penicillin as a result of timely pathogen-based diagnosis.

CONCLUSIONS

Physicians should inquire about recent rat exposure and consider the possibility of RBF when a patient develops unexplained fever and rashes. mNGS is a new diagnostic technology and may identify RBF pathogens even when blood culture results are negative.

High rates of potentially infectious exposures between immunocompromised patients and their companion animals: an unmet need for education

A cross-sectional survey of 265 adult patients with haematological malignancy, haemoglobinopathy or human immunodeficiency virus was performed to determine the potential risk of infection from animal exposures. One hundred and thirty-seven (52%) owned an animal; the majority were dogs (74%) and cats (39%), but 14% owned birds and 3% reptiles. Eighty percent engaged in behaviour with their animals that potentially put them at risk of zoonotic infections. The most frequent behaviours were picking up animal faeces 72 (52%), cleaning animal areas 69 (50%) and allowing animals to sleep in the same bed 51 (37%). Twenty-eight percent allowed the animal to lick their face. Of all patients, 80 (30%) had been bitten or scratched by an animal. Only 16% of those who owned pets could recall receiving education regarding safe behaviours around animals. These immunocompromised patients are at risk of infection through exposure to pets. Our study highlights the need for increased education of patients regarding how to remain safe around their pets.

Streptobacillus moniliformis bacteremia in a rheumatoid arthritis patient without a rat bite: a case report

Background

Rat bite fever is a relatively rare infectious disease due to infection with Streptobacillus moniliformis or Spirillum minus mainly via directs bite by rats, mice, or other rodents. If there is no clear bite history, the diagnosis is difficult or may not be made.

Case presentation

A 72-year-old Asian female with rheumatoid arthritis was admitted for high grade fever and walking difficulty with severe lumbago. Initially, we suspected lumber compression fracture with deterioration of rheumatoid arthritis, but Gram-negative bacilli were isolated from blood culture during hospitalization. The isolated organism was identified as S. moniliformis by 16S ribosomal ribonucleic acid (rRNA) sequencing. S. moniliformis is well known to be a primary causative organism of rat bite fever, but this patient had no history of rat bite. Had S. moniliformis bacteremia not been detected, she might have been treated for rheumatic exacerbation.

Conclusion

We emphasize the importance of performing appropriate microbial culture testing for identifying potential infectious diseases. We also conclude that S. moniliformis infection can become established with contaminated vehicle contact alone, not only as a direct result of a bite. We must keep mind that those working in places where rodents breed or are at risk of contact with rats or mice might be at risk for contracting this unusual disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-015-1642-6) contains supplementary material, which is available to authorized users.