Rat bite fever

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.

[New awareness for zoonoses using the example of rat bite fever : Case report and literature review]

BACKGROUND

Rat bite fever is a rare but potentially fatal bacterial zoonosis. The symptoms can be unspecific, but severe sepsis can be associated with involvement of different organs.

CASE REPORT

A 27-year-old homeless man presented with fever, suspected meningitis, acute renal failure, unclear skin lesions as well as joint problems and muscular pain. Bite wounds were not detected. Meningitis could be excluded after lumbar puncture, and there was no evidence of endocarditis as the cause of the skin lesions. After 72 h, growth of Streptobacillus moniliformis in blood cultures was detected. Clinical symptoms were compatible with the diagnosis of rat bite fever. Calculated antibiosis with ampicillin sulbactam and doxycycline led to regression of the symptoms.

CONCLUSION

Rat bite fever poses a diagnostic challenge due unspecific symptoms, diverse differential diagnostic options, and challenging microbiological detection. Patient history is of the utmost importance. Due to the rarity of the disease, this case report is intended to raise awareness.

Streptobacillus moniliformis and IgM and IgG Immune Response in Patient with Endocarditis1

We describe a case of endocarditis caused by Streptobacillus moniliformis bacteria, a known cause of rat-bite fever, in a 32-year-old woman with pet rats in Germany. The patient had a strong serologic response, with high IgM and IgG titers. Serologic analysis is a promising tool to identify S. moniliformis bacterial infection.

Zoonotic Pathogens Associated with Pet and Feeder Murid Rodent Species: A Global Systematic Review

Background: Pet and feeder rodents are one of the main sources of emerging infectious diseases. These rodents are purchased from pet shops, breeders, and online. Consequently, some of these rodents may subtly transmit diseases as they may be asymptomatic to certain pathogens. Materials and Methods: We systematically searched four academic databases viz. Google Scholar, PubMed, Web of Science, and Scopus to determine zoonotic pathogens associated with pet and feeder rodents globally. Our searches were performed in R statistical software using the packages "metagear" and "revtool". Results: We found 62 studies reporting on zoonotic pathogens between 1973 and 2022 from 16 countries representing 4 continents, namely Africa, Europe, Asia, and North America. The review identified 30 zoonotic pathogens isolated from pet and feeder rodents, including the African pygmy mouse (Mus minutoides), brown rat (Rattus norvegicus), and the house mouse (Mus musculus). The greatest number of pathogens was reported from the United States, followed by Togo and the United Kingdom. Bacterial pathogens were the most prevalent. However, the Seoul virus and rat bite fever (Streptobacillus moniliformis) were the most studied pathogens, found in more than one country, with reported outbreak cases. Most of the zoonotic pathogens were isolated from rodents acquired from pet shops. Conclusions: We recommend that pet and feeder rodents purchased from pet shops should be regularly screened for potential zoonotic pathogens as some of these animals may not show clinical signs of the illness. There is also a critical need to develop strict regulations and policies, especially in underdeveloped and developing regions for an effective surveillance process, which will include early detection, rapid response, and control of zoonotic diseases globally.

Rat bite fever mimicking ANCA-associated vasculitis

Rat bite fever (RBF) is a rare infectious zoonotic disease caused by two bacterial species: the Gram-negative rod Streptobacillus moniliformis and the Gram-negative coiled rod Spirillum minus. The association between RBF and skin vasculitis and arthritis has been observed. The aim of this paper was to present a case of rat-bite fever with symptoms of skin vasculitis and arthritis, associated with high titers of ANCA antibodies and anti-endothelial cell antibodies suggestive of primary vasculitis. The patient was successfully treated with antibiotics and non-steroidal anti-inflammatory drugs, leading to significant improvement. Based on the presented case, we discuss the differential diagnosis of the signs and the role of infection in the induction of ANCA antibodies. We reviewed the English language literature for cases of RBF presenting with symptoms of vasculitis and/or antibody presence. A literature review was performed in PubMed and Google using the keywords "rat bite fever" AND "vasculitis", "systemic vasculitis", "ANCA", "antiendothelial antibodies". No cases of rat-bite fever with the presence of ANCA antibodies or AECA antibodies in its course have been described thus far. Rat bite fever is a rare disease with nonspecific symptoms. In its course, general weakness, intermittent fever, leukocytoclastic vasculitis, and arthritis are reported. To our knowledge, this is the first reported case of ANCA positivity associated with RBF.

Rat-Bite Fever in a 34-Year-Old Female

Rat-bite fever (RBF) is a rare systemic infectious disease caused by Streptobacillus moniliformis, Spirillum minus, or Streptobacillus notomytis. As the name implies, the disease is typically transmitted by a rat bite. RBF usually presents as a combination of fever, arthritis, and rash. Definitive diagnosis of RBF may prove difficult, as the responsible bacteria are not easily identified with standard testing. We describe a case of RBF in a 34-year-old female who presented with fever, chills, polyarthralgia, and skin rash following a rat bite. Initial vital signs were remarkable for fever and tachycardia. Physical examination revealed an erythematous vesicular and papular rash involving her extremities, buttocks, and oral mucosa. Blood cultures were negative. A skin biopsy revealed leukocytoclastic vasculitis and was negative for Gram stain. Further analysis using specialized immunohistochemistry and polymerase chain reaction (PCR) identified S. moniliformis. A diagnosis of RBF was made, and the patient was successfully treated with a two-week course of doxycycline.

Streptobacillus moniliformis Bacteremia in a Patient with Reactive Arthritis Without a Bite: A Case Report

Introduction: Clinically, rat bite fever (RBF) is a condition caused by Spirillum minus or Streptobacillus moniliformis infections, following rat or any rodent bite. In the absence of a rat bite, this condition cannot be accurately diagnosed. Here, we report the first case of RBF due to S. moniliformis but without a rat bite in China. Case Presentation: A 77-year-old woman with reactive arthritis was admitted to the hospital due to high fever. Initially, we suspected reactive arthritis with liver function deterioration. However, we isolated a bacterium which was confirmed to be S. moniliformis using Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Subsequently, the patient was given targeted anti-infective treatment, which completely resolved the symptoms. The patient was discharged upon fully recovery. Conclusions: Rat bite fever infection caused by S. moniliformis may occur without actual rodent bite. MALDI-TOF MS may be applied to determine the diagnosis of RBF. Difficulties in pathogen and clinical diagnosis highlight the need for discovering the complete exposure history and a greater understanding of this rare zoonotic infections.

Development and validation of a triplex real-time qPCR for sensitive detection and quantification of major rat bite fever pathogen Streptobacillus moniliformis

Streptobacillus (S.) moniliformis is the most important pathogen causing rat bite fever (RBF) worldwide. This zoonotic pathogen is understudied mainly due to difficulties in culturing S. moniliformis as a fastidious microorganism. Therefore, advances in molecular detection techniques are highly needed, especially with regard to the widespread availability of real-time quantitative (q) PCR in laboratories. In this study, we aimed to develop a qPCR for the identification of Streptobacillus species and quantification of S. moniliformis in clinical samples, especially those derived from tissue samples of animal origin. We optimized a previously described PCR protocol in order to develop a qPCR, which can detect different Streptobacillus species with high specificity and is simultaneously able to quantitate S. moniliformis in different clinical matrices. The qPCR exhibited a limit of detection (LOD) of 21 copies/reaction representing ~4-5 streptobacilli, while the limit of quantification (LOQ) was 2.1 × 10³ copies/reaction. It was also more sensitive than conventional PCR by two orders of magnitude and proved to have a substantial agreement (Kappa 0.74) compared to it with a superior detection rate in 374 samples from wild rats, laboratory rats and animals from holdings of wild-trapped rats. To conclude, the qPCR described in this study is an important molecular tool that is able to quantify S. moniliformis in tissue samples of animal origin. It represents a suitable tool for future establishment and evaluation of other molecular assays that are highly needed for a better understanding of epidemiology and pathophysiology of RBF. In experimental studies, it will also be useful for titration purposes since the quantification of the organism using classical plate counting technique is problematic and inaccurate.

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.

Rat bite fever, a diagnostic challenge: case report and review of 29 cases

Rats can transmit Streptobacillus moniliformis, which may cause rat-bite fever (RBF), a rare and potentially lethal zoonosis. Fastidious in vitro growth and unspecific symptoms, including fever, arthralgia, and polymorphous skin lesions, complicate the diagnosis. Rat-bite fever follows exposure to contaminated bodily fluids of infected rodents; however, reports on Streptobacillus moniliformis-related infections are few so far. A female patient presented with painful hemorrhagic pustules and purpuric lesions on hands and feet. She developed fever and migratory polyarthralgia. Blood culture yielded growth with Streptobacillus moniliformis. The patient owned rats and handled contaminated rat feces and urine, making this the most likely etiology of infection. We report a case of RBF due to Streptobacillus moniliformis in a rat handling-patient. Difficulties in clinical and microbiological diagnosis highlight the need for a thorough and complete history-taking and a greater understanding of this rare infectious disease.

Geospatial Modelling and Univariate Analysis of Commensal Rodent-Borne Cestodoses: The Case of Invasive spp. of Rattus and Indigenous Mastomys coucha From South Africa

Poor socio-economic and unsanitary conditions are conducive to commensal rodent infestations, and these conditions are widespread in South Africa. Cestode species of zoonotic interest are highly prevalent in commensal rodents, such as invasive Rattus norvegicus, Rattus rattus, Rattus tanezumi, and indigenous Mastomys coucha, and have been frequently recovered from human stool samples. These cestode species have similar transmission dynamics to traditional soil-transmitted helminths (STHs), which ties them to infections associated with poverty and poor sanitation. Univariate analysis was used in the present study to determine the association between rodent-related factors and cestode prevalence, while ecological niche modelling was used to infer the potential distribution of the cestode species in South Africa. Cestode prevalence was found to be associated with older rodents, but it was not significantly associated with sex, and ectoparasite presence. The predicted occurrence for rodent-borne cestodes predominantly coincided with large human settlements, typically associated with significant anthropogenic changes. In addition, cestode parasite occurrence was predicted to include areas both inland and along the coast. This is possibly related to the commensal behaviour of the rodent hosts. The study highlights the rodent-related factors associated with the prevalence of parasites in the host community, as well as the environmental variables associated with parasite infective stages that influence host exposure. The application of geospatial modelling together with univariate analysis to predict and explain rodent-borne parasite prevalence may be useful to inform management strategies for targeted interventions.

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.

Sneathia: an emerging pathogen in female reproductive disease and adverse perinatal outcomes

Sneathia is an emerging pathogen implicated in adverse reproductive and perinatal outcomes. Although scarce, recent data suggest that vaginally residing Sneathia becomes pathogenic following its ascension into the upper urogenital tract, amniotic fluid, placenta, and foetal membranes. The role of Sneathia in women's health and disease is generally underappreciated because the cultivation of these bacteria is limited by their complex nutritional requirements, slow growth patterns, and anaerobic nature. For this reason, molecular methods are typically required for the detection and differential diagnosis of Sneathia infections. Here, we review the laboratory methods used for the diagnosis of Sneathia infections, the molecular mechanisms underlying its virulence, and its sensitivity to antibiotics. We further review the evidence of Sneathia's contributions to the pathogenesis of bacterial vaginosis, chorioamnionitis, preterm prelabour rupture of membranes, spontaneous preterm labour, stillbirth, maternal and neonatal sepsis, HIV infection, and cervical cancer. Collectively, growing evidence indicates that Sneathia represents an important yet underappreciated pathogen affecting the development and progression of several adverse clinical conditions diagnosed in pregnant women and their neonates, as well as in non-pregnant women.

Rat Bite Fever: The First Case Report from Qatar

Patient: Male, 37-year-old

Final Diagnosis: Rat bite fever

Symptoms: Acute gastroenteritis • fever • headache • loose stools • vomiting

Medication: —

Clinical Procedure: —

Specialty: Critical Care Medicine • Dermatology • Infectious Diseases • Public Health

Streptobacillus felis, a member of the oropharynx microbiota of the Felidae, isolated from a tropical rusty-spotted cat

Streptobacillus felis is a fastidious microorganism and a novel member of the potentially zoonotic bacteria causing rat bite fever. Since its description, this is the second isolation of S. felis in a diseased member of the Felidae. Interestingly, the strain from this study was isolated from a zoo held, rusty-spotted cat (Prionailurus rubiginosus), with pneumonia, thereby indicating a possible broader host range in feline species. A recent preliminary sampling of domestic cats (Felis silvestris forma catus) revealed that this microorganism is common in the oropharynx, suggesting that S. felis is a member of their normal microbiota. Due to unawareness, fastidiousness, antibiotic sensitivity and lack of diagnostics the role of S. felis as a cat and human pathogen might be under-reported as with other Streptobacillus infections. More studies are necessary to elucidate the role of S. felis in domestic cats and other Felidae in order to better estimate its zoonotic potential.

Rat-Bite Fever in the United States: An Analysis Using Multiple National Data Sources, 2001-2015

BACKGROUND

Rat-bite fever is a rare disease associated with rat bites or direct/indirect rodent contact.

METHODS

We examined rat-bite fever and rat-bite injury diagnoses in the United States during 2001-2015. We analyzed national, state, and Indian Health Service healthcare encounter datasets for rat-bite fever and rat-bite injury diagnoses. We calculated average-annual encounter rates per 1 000 000 persons.

RESULTS

Nationally, the rat-bite fever Emergency Department visit rate was 0.33 (95% confidence interval [CI], 0.19-0.47) and the hospitalization rate was 0.20 (95% CI, 0.17-0.24). The rat-bite injury Emergency Department visit rate was 10.51 (95% CI, 10.13-10.88) and the hospitalization rate was 0.27 (95% CI, 0.23-0.30). The Indian Health Service Emergency Department/outpatient visit rate was 3.00 for rat-bite fever and 18.89 for rat-bite injury. The majority of rat-bite fever encounters were among individuals 0-19 years of age.

CONCLUSIONS

Our results support the literature that rat-bite fever is rare and affects children and young adults. Targeted education could benefit specific risk groups.

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.

Rat Bite Fever: A Case Report and Review of the Literature

Cases of rat-bite fever (RBF) were reported in the literature for more than 2000 years. Not until recently, however, were attempts made to differentiate between RBF and Streptobacillus moniliformis septic arthritis, 2 arguably different clinical entities. There are limited data regarding S moniliformis septic arthritis and the features that distinguish it from RBF, and most conclude that although clinically disparate diseases, it is difficult to differentiate between them. We report a case of a 17-year-old girl who presented with S moniliformis bacteremia and symptoms that spanned both RBF and S moniliformis septic arthritis. This case emphasizes the difficulty in differentiating the 2 clinical entities and the importance of early diagnosis, proper clinical suspicion, and prompt treatment to achieve positive outcomes.

Bacterial isolation from internal organs of rats (Rattus rattus) captured in Baghdad city of Iraq

Aim

Rats are accused in disseminating many zoonotic diseases. This study aimed to isolate and identify bacteria from internal organs of rats captured in Baghdad City, Iraq.

Materials and Methods

A total of 120 black rats (R. rattus) were trapped from different areas in Baghdad city. Rats were kept in individual plastic cages for 3 h before euthanizing. Deep pharyngeal swab, intestinal content, urine, and pieces of the liver and spleen, lung, kidney, and brain were obtained aseptically. The specimens were inoculated into peptone water and incubated at 37°C for 24 h for enrichment. A loopful of each specimen was then subcultured onto MacConkey Agar, Blood Agar, and Mannitol Salt Agar. CHROMagar O157 H7 and CHROMagar Listeria were used to detect Escherichia coli 157:7 and Listeria spp., respectively. Biochemical tests on analytical profile index, microscopic examination, and commercial kit for latex agglutination test for serotyping E. coli O157:H7 were used.

Results

Mixed bacterial isolates were recorded as 116, 52, 36, 28, 18, 6, and 4 from intestinal contents, deep pharyngeal, liver and spleen, urine, lung, brain, and kidney, respectively. Microorganisms included E. coli, Staphylococcus aureus, Streptococcus spp., Bacillus spp., Pseudomonas aeruginosa, Citrobacter freundii, Proteus vulgaris, E. coli O157:H7, Enterobacter cloacae, Listeria spp., Klebsiella spp., Ochrobactrum anthropi, Aeromonas spp., Brucella spp., Pseudomonas fluorescens, Escherichia fergusonii, Micrococcus spp., Morganella spp., Proteus mirabilis, Pseudomonas luteola, and Streptobacillus spp. The highest bacterial prevalence (88; 73.33%) was recorded for E. coli, where 68 isolates were identified from the intestinal contents. Of these, four isolates were E. coli O157:H7.

Conclusion

Rats are important carriers and transmitters of a number of pathogens and can disseminate these microorganisms to humans and animals.

Clinical infection in house rats (Rattus rattus) caused by Streptobacillus notomytis

Rat bite fever is an under-reported, under-diagnosed emerging zoonosis with worldwide distribution. Besides Spirillum minus, Streptobacillus moniliformis is the major causative microorganism although it usually colonises rats without any clinical signs. A group of house rats (Rattus rattus) kept in a zoo exhibition for educational purposes suffered from neurological signs including disorientation, torticollis, stall walking, ataxia and death. Gross pathological and histo-pathological examinations of the investigated rats revealed high-grade otitis interna et media, from which Streptobacillus notomytis was isolated in pure culture or as the predominant microorganism. This case series underlines a previously expressed hypothesis that R. rattus might be naturally colonised with S. notomytis, whereas the traditional rat bite fever organism, S. moniliformis, might be restricted to the Norway rat (Rattus norvegicus). However, the general paucity of Streptobacillus isolates, especially from their respective animal hosts, precludes definitive proof of these host tropisms. This is the first report of S. notomytis detection outside Asia and Australia and the first evidence for its role as a facultative pathogen in house rats.

Rat-bite fever due to Streptobacillus notomytis isolated from a human specimen

Rat-bite fever (RBF) is a disease that usually presents with fever, arthralgia and skin rash. Streptobacillus moniliformis was considered the main cause of RBF among the genus Streptobacillus. Although with similar clinical presentation, RBF due to Streptobacillus notomytis is unusual in humans. To the best of our knowledge, we present a case involving the first isolate of S. notomytis in humans. A 63-year-old woman was admitted to our hospital with fever, rash and polyarthritis. She recalled being bitten by a rat on her finger 5 days before presentation. Clinical manifestations were compatible with rat-bite fever (RBF) and the diagnosis was confirmed by the detection of Streptobacillus species from both blood and pustule samples. Initial polymerase chain reaction tests revealed that the organism was S. moniliformis. However, thorough genetic analysis revealed the organism to be S. notomytis. The condition was successfully treated with ampicillin.

Comparative analysis of clinics, pathologies and immune responses in BALB/c and C57BL/6 mice infected with Streptobacillus moniliformis

Streptobacillus (S.) moniliformis is a rat-associated zoonotic pathogen that occasionally causes disease in other species. We investigated the working hypothesis that intranasal infection might lead to different immune responses in C57BL/6 and BALB/c mice associated with distinct pathologies. This study confirmed with 75% mortality the known high susceptibility of C57BL/6 mice to Streptobacillus moniliformis infection in comparison to BALB/c mice which did not develop signs of disease. Main pathologies in C57BL/6 mice were purulent to necrotizing lymphadenitis and pneumonia. Significant seroconversion was recorded in surviving mice of both strains. Differentiation of IgG-subclasses revealed mean ratios of IgG2b to IgG1 below 0.5 in sera of all mice prior to infection and of BALB/c mice post infection. In contrast, C57BL/6 mice had a mean IgG2b/IgG1 ratio of 2.5 post infection indicating a Th1 immune response in C57BL/6 versus a Th2 response in BALB/c mice. Evaluation of different sentinel systems revealed that cultural and serological investigations of these animals might not be sufficient to detect infection. In summary, an intranasal S. moniliformis infection model in C57BL/6 mice leading to purulent to necrotizing inflammations in the lung, the lymph nodes and other organs associated with a Th1 immune response is described.

A spinal epidural abscess due to Streptobacillus moniliformis infection following a rat bite: case report

The authors describe the case of a 40-year-old man suffering from an epidural abscess in the thoracic spine due to a rarely isolated pathogen, Streptobacillus moniliformis, the causative agent of rat bite fever. Besides diffuse abdominal pain, ataxia, paresthesia, hypesthesia, and enhanced reflexes of the lower extremities, the patient suffered from a decreased sensation of bladder filling. His history was also positive for a rat bite 6 weeks earlier. Magnetic resonance imaging showed an epidural, space-occupying lesion compressing the spinal cord at the vertebral levels of T6-8. Neurosurgery revealed an epidural abscess, which was drained via laminectomy (T-7) and excision of the ligamentum flavum (T6-8). The etiological agent S. moniliformis was identified by 16S rRNA-based polymerase chain reaction and sequencing as well as by culture and mass spectrometry. Treatment with penicillin G led to complete resolution of the abscess and clinical recovery of the patient, who regained his bladder-filling sensation and free walking ability. This case demonstrates that careful attention to the patient's history is essential in suspecting unusual bacterial pathogens as the cause of an epidural abscess and initiating the optimal diagnostic procedure and antimicrobial therapy.

A Case Study of Rat Bite Fever Caused by Streptobacillus moniliformis

We report a case of rat bite fever, diagnosed based on positive cultures of Streptobacillus moniliformis from blood and synovial fluid. The patient was a 45-year-old man who presented with history of a rat bite and alcoholic liver cirrhosis. He had been bitten on his third finger by a rat, which was caught in a mousetrap installed in his house. Over the course of approximately 2 weeks after the bite, the patient developed fever, rash, and arthralgia. The patient was admitted to our hospital and treated with a combination of ampicillin-sulbactam, vancomycin (VAN), and minocycline (MIN) antibiotics. Initial culture findings from the Anaerobic/F resin blood culture were positive for gram-negative bacillus after overnight incubation. Thus, S. moniliformis infection was suspected, and administration of VAN and MIN was ceased. On hospital day 8, the treatment was switched to oral amoxicillin-clavulanic acid, and the patient was discharged from the hospital. Subsequently, the pathogen was also detected in synovial fluid and identified as S. moniliformis using 16S rRNA sequencing analysis.

Phylogenetic and comparative genomics of the family Leptotrichiaceae and introduction of a novel fingerprinting MLVA for Streptobacillus moniliformis

Background

The Leptotrichiaceae are a family of fairly unnoticed bacteria containing both microbiota on mucous membranes as well as significant pathogens such as Streptobacillus moniliformis, the causative organism of streptobacillary rat bite fever. Comprehensive genomic studies in members of this family have so far not been carried out. We aimed to analyze 47 genomes from 20 different member species to illuminate phylogenetic aspects, as well as genomic and discriminatory properties.

Results

Our data provide a novel and reliable basis of support for previously established phylogeny from this group and give a deeper insight into characteristics of genome structure and gene functions. Full genome analyses revealed that most S. moniliformis strains under study form a heterogeneous population without any significant clustering. Analysis of infra-species variability for this highly pathogenic rat bite fever organism led to the detection of three specific variable number tandem analysis loci with high discriminatory power.

Conclusions

This highly useful and economical tool can be directly employed in clinical samples without laborious prior cultivation. Our and prospective case-specific data can now easily be compared by using a newly established MLVA database in order to gain a better insight into the epidemiology of this presumably under-reported zoonosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-3206-0) contains supplementary material, which is available to authorized users.

Streptobacillus notomytis sp. nov., isolated from a spinifex hopping mouse (Notomys alexis Thomas, 1922), and emended description of Streptobacillus Levaditi et al. 1925, Eisenberg et al. 2015 emend

A pleomorphic, Gram-negative, rod-shaped, indole-, oxidase- and catalase-negative, non-spore-forming, non-motile bacterium was isolated in 1979 from the heart of a spinifex hopping mouse (Notomys alexis Thomas, 1922) with septicaemia and stored as Streptobacillus moniliformis in the strain collection of the Animal Health Laboratory, South Perth, Western Australia (AHL 370-1), as well as under CCUG 12425. On the basis of 16SrRNA gene sequence analyses, the strain was assigned to the genus Streptobacillus, with 99.4 % sequence similarity to the type strain of Streptobacillus moniliformis, 95.6 %sequence similarity to the type strain of Streptobacillus hongkongensis and 99.0 %sequence similarity to the type strain of Streptobacillus felis. The clear differentiation of strain AHL 370-1T from Streptobacillus moniliformis, Streptobacillus hongkongensis and Streptobacillus felis was also supported by rpoB, groEL and recA nucleotide and amino acid sequence analysis. Average nucleotide identity was 87.16 % between strain AHL 370-1T and Streptobacillus moniliformis DSM 12112T. Physiological data confirmed the allocation of strain AHL 370-1T to the family Leptotrichiaceae, considering the very similar profiles of enzyme activities and fatty acids compared to closely related species. Within the genus Streptobacillus,isolate AHL 370-1T could also be separated unambiguously from the type strains of Streptobacillus moniliformis, Streptobacillus hongkongensis and Streptobacillus felis by MALDI-TOF mass spectrometry. Two further strains (KWG2 and KWG24) isolated from asymptomatic black rats in Japan were highly similar to AHL 370-1T. On the basis of these data, we propose the novel species Streptobacillus notomytis sp. nov., with the type strain AHL370-1T (=CCUG 12425T=DSM 100026T=CCM 8593T=EF 12425T).

Pleiomorphism in Mycobacterium

Morphological variants in mycobacterial cultures under different growth conditions, including aging of the culture, have been shown to include fibrous aggregates, biofilms, coccoids, and spores. Here we discuss the diversity in shape and size changes demonstrated by bacterial cells with special reference to pleiomorphism observed in Mycobacterium spp. in response to nutritional and other environmental stresses. Inherent asymmetry in cell division and compartmentalization of cell interior under different growth conditions might contribute toward the observed pleiomorphism in mycobacteria. The regulatory genes comprising the bacterial signaling pathway responsible for initiating morphogenesis are speculated upon from bioinformatic identifications of genes for known sensors, kinases, and phosphatases existing in mycobacterial genomes as well as on the basis of what is known in other bacteria.

Approved and novel strategies in diagnostics of rat bite fever and other Streptobacillus infections in humans and animals

Rat bite fever (RBF), a worldwide occurring and most likely under-diagnosed zoonosis caused by Streptobacillus moniliformis, represents the most prominent disease of Streptobacillus infections. Recently, novel members have been described, from which a reservoir in rats and other animal species and a zoonotic potential can be assumed. Despite regularly published case reports, diagnostics of RBF continues to represent a 'diagnostic dilemma', because the mostly applied 16S rRNA sequence analysis may be uncertain for proper pathogen identification. Virtually nothing is known regarding prevalence in humans and animal reservoirs. For a realistic assessment of the pathogen's spread, epidemiology and virulence traits, future studies should focus on the genomic background of Streptobacillus. Full genome sequence analyses of a representative collection of strains might facilitate to unequivocally identify and type isolates. Prevalence studies using selective enrichment mechanisms may also enable the isolation of novel strains and candidate species of this neglected group of microorganisms.

Recurrent Fever in Children

Children presenting with recurrent fever may represent a diagnostic challenge. After excluding the most common etiologies, which include the consecutive occurrence of independent uncomplicated infections, a wide range of possible causes are considered. This article summarizes infectious and noninfectious causes of recurrent fever in pediatric patients. We highlight that, when investigating recurrent fever, it is important to consider age at onset, family history, duration of febrile episodes, length of interval between episodes, associated symptoms and response to treatment. Additionally, information regarding travel history and exposure to animals is helpful, especially with regard to infections. With the exclusion of repeated independent uncomplicated infections, many infective causes of recurrent fever are relatively rare in Western countries; therefore, clinicians should be attuned to suggestive case history data. It is important to rule out the possibility of an infectious process or a malignancy, in particular, if steroid therapy is being considered. After excluding an infectious or neoplastic etiology, immune-mediated and autoinflammatory diseases should be taken into consideration. Together with case history data, a careful physical exam during and between febrile episodes may give useful clues and guide laboratory investigations. However, despite a thorough evaluation, a recurrent fever may remain unexplained. A watchful follow-up is thus mandatory because new signs and symptoms may appear over time.

Streptobacillus ratti sp. nov., isolated from a black rat (Rattus rattus)

An indole-, oxidase- and catalase-negative, non-motile bacterium, strain OGS16T, was isolated from an oral swab of a feral black rat (Rattus rattus) in 2007 in Japan. It stained Gram-negative and had pleomorphic, rod-shaped, non-spore-forming cells. Based on 16S rRNA gene sequence analyses, strain OGS16T was assigned to the genus Streptobacillus, with 16S rRNA gene sequence similarities of 99.3, 99.0, 98.6 and 95.5% to the type strains of Streptobacillus moniliformis, Streptobacillus notomytis, Streptobacillus felis and Streptobacillus hongkongensis, respectively. Strain OGS16T could also be differentiated clearly from other species of the genus Streptobacillus by rpoB, groEL and recA nucleotide and deduced amino acid sequence analysis. DNA-DNA relatedness as obtained by average nucleotide identity was 89.10% between strain OGS16T and Streptobacillus moniliformis DSM 12112T. Chemotaxonomic and physiological data for strain OGS16T were congruent with results for other closely related members of the family Leptotrichiaceae, represented by highly similar enzyme profiles and fatty acid patterns. MALDI-TOF MS analysis also proved suitable in discriminating strain OGS16T unequivocally from all currently described taxa of the genus Streptobacillus. On the basis of these data, we propose the novel species Streptobacillus ratti sp. nov., with the type strain OGS16T (=JCM 31098T=DSM 101843T). The G+C content of the DNA of the type strain is 25.9 mol% and the genome size is 1.50 Mbp.

Aboriginal and invasive rats of genus Rattus as hosts of infectious agents

From the perspective of ecology of zoonotic pathogens, the role of the Old World rats of the genus Rattus is exceptional. The review analyzes specific characteristics of rats that contribute to their important role in hosting pathogens, such as host-pathogen relations and rates of rat-borne infections, taxonomy, ecology, and essential factors. Specifically the review addresses recent taxonomic revisions within the genus Rattus that resulted from applications of new genetic tools in understanding relationships between the Old World rats and the infectious agents that they carry. Among the numerous species within the genus Rattus, only three species-the Norway rat (R. norvegicus), the black or roof rat (R. rattus), and the Asian black rat (R. tanezumi)-have colonized urban ecosystems globally for a historically long period of time. The fourth invasive species, R. exulans, is limited to tropical Asia-Pacific areas. One of the points highlighted in this review is the necessity to discriminate the roles played by rats as pathogen reservoirs within the land of their original diversification and in regions where only one or few rat species were introduced during the recent human history.

Phenotypic and Genotypic Characteristics of Members of the Genus Streptobacillus

The genus Streptobacillus (S.) remained monotypic for almost 90 years until two new species were recently described. The type species, S. moniliformis, is one of the two etiological agents of rat bite fever, an under-diagnosed, worldwide occurring zoonosis. In a polyphasic approach field isolates and reference strains of S. moniliformis, S. hongkongensis, S. felis as well as divergent isolates were characterized by comparison of molecular data (n = 29) and from the majority also by their physiological as well as proteomic properties (n = 22). Based on growth-independent physiological profiling using VITEK2-compact, API ZYM and the Micronaut system fastidious growth-related difficulties could be overcome and streptobacilli could definitively be typed despite generally few differences. While differing in their isolation sites and dates, S. moniliformis isolates were found to possess almost identical spectra in matrix-assisted laser desorption ionization-time of flight mass spectrometry and Fourier transform infrared spectroscopy. Spectroscopic methods facilitated differentiation of S. moniliformis, S. hongkongensis and S. felis as well as one divergent isolate. Sequencing of 16S rRNA gene as well as functional genes groEL, recA and gyrB revealed only little intraspecific variability, but generally proved suitable for interspecies discrimination between all three taxa and two groups of divergent isolates.

Streptobacillus felis sp. nov., isolated from a cat with pneumonia, and emended descriptions of the genus Streptobacillus and of Streptobacillus moniliformis

A pleomorphic, Gram-stain-negative, rod-shaped, indole-, oxidase- and catalase-negative, non-spore-forming, non-motile bacterium (strain 131000547T) was isolated from the lungs of a cat with pneumonia. On the basis of 16S rRNA gene sequence analyses the strain was assigned to the genus Streptobacillus with 97.6  % sequence similarity to the type strain of Streptobacillus moniliformis and 94.6  % to that of Streptobacillus hongkongensis. The clear differentiation of strain 131000547T from Streptobacillus moniliformis and Streptobacillus hongkongensis was also supported by gyrB, groEL, and recA nucleotide and amino acid sequence analysis. DNA–DNA hybridization demonstrated ≤ 19.9  % (reciprocal 28.7  %) DNA–DNA relatedness between strain 131000547T and Streptobacillus moniliformis DSM 12112T. Physiological data confirmed the allocation of strain 131000547T to the family Leptotrichiaceae. Strain 131000547T has a unique profile of enzyme activities allowing differentiation from the most closely related species. Within the genus Streptobacillus, isolate 131000547T could also unambiguously be separated from Streptobacillus moniliformis and Streptobacillus hongkongensis by both matrix-assisted laser desorption ionization time-of-flight mass spectrometry and Fourier transform-infrared spectroscopy. On the basis of these data, a novel species of the genus Streptobacillus, Streptobacillus felis sp. nov., is proposed with the type strain 131000547T ( = DSM 29248T = CCUG 66203T = CCM 8542T). Emended descriptions of the genus Streptobacillus and of Streptobacillus moniliformis are also given.

Bacterial Zoonoses Transmitted by Household Pets: State-of-the-Art and Future Perspectives for Targeted Research and Policy Actions

The close contact between household pets and people offers favourable conditions for bacterial transmission. In this article, the aetiology, prevalence, transmission, impact on human health and preventative measures are summarized for selected bacterial zoonoses transmissible by household pets. Six zoonoses representing distinct transmission routes were selected arbitrarily based on the available information on incidence and severity of pet-associated disease caused by zoonotic bacteria: bite infections and cat scratch disease (physical injuries), psittacosis (inhalation), leptospirosis (contact with urine), and campylobacteriosis and salmonellosis (faecal-oral ingestion). Antimicrobial resistance was also included due to the recent emergence of multidrug-resistant bacteria of zoonotic potential in dogs and cats. There is a general lack of data on pathogen prevalence in the relevant pet population and on the incidence of human infections attributable to pets. In order to address these gaps in knowledge, and to minimize the risk of human infection, actions at several levels are recommended, including: (1) coordinated surveillance of zoonotic pathogens and antimicrobial resistance in household pets, (2) studies to estimate the burden of human disease attributable to pets and to identify risk behaviours facilitating transmission, and (3) education of those in charge of pets, animal caretakers, veterinarians and human medical healthcare practitioners on the potential zoonotic risks associated with exposure to pets. Disease-specific recommendations include incentives to undertake research aimed at the development of new diagnostic tests, veterinary-specific antimicrobial products and vaccines, as well as initiatives to promote best practices in veterinary diagnostic laboratories and prudent antimicrobial usage.

Genomic sequence analysis and characterization of Sneathia amnii sp. nov

BACKGROUND

Bacteria of the genus Sneathia are emerging as potential pathogens of the female reproductive tract. Species of Sneathia, which were formerly grouped with Leptotrichia, can be part of the normal microbiota of the genitourinary tracts of men and women, but they are also associated with a variety of clinical conditions including bacterial vaginosis, preeclampsia, preterm labor, spontaneous abortion, post-partum bacteremia and other invasive infections. Sneathia species also exhibit a significant correlation with sexually transmitted diseases and cervical cancer. Because Sneathia species are fastidious and rarely cultured successfully in vitro; and the genomes of members of the genus had until now not been characterized, very little is known about the physiology or the virulence of these organisms.

RESULTS

Here, we describe a novel species, Sneathia amnii sp. nov, which closely resembles bacteria previously designated "Leptotrichia amnionii". As part of the Vaginal Human Microbiome Project at VCU, a vaginal isolate of S. amnii sp. nov. was identified, successfully cultured and bacteriologically cloned. The biochemical characteristics and virulence properties of the organism were examined in vitro, and the genome of the organism was sequenced, annotated and analyzed. The analysis revealed a reduced circular genome of ~1.34 Mbp, containing ~1,282 protein-coding genes. Metabolic reconstruction of the bacterium reflected its biochemical phenotype, and several genes potentially associated with pathogenicity were identified.

CONCLUSIONS

Bacteria with complex growth requirements frequently remain poorly characterized and, as a consequence, their roles in health and disease are unclear. Elucidation of the physiology and identification of genes putatively involved in the metabolism and virulence of S. amnii may lead to a better understanding of the role of this potential pathogen in bacterial vaginosis, preterm birth, and other issues associated with vaginal and reproductive health.

Rat bite fever: fever, arthritis, and rash in a 4-year-old boy

Rat bite fever is a rare but potentially fatal Gram-negative infection that predominantly affects populations with exposure to rats, notably children. The clinical presentation is nonspecific and requires a high threshold of suspicion to elicit a history of rat exposure. We report here a case of a child whose diagnosis was made retrospectively but with good outcome.

Animal bite-associated infections: microbiology and treatment

Human and animal bites may lead to serious infection. The organisms involved tend to originate from the oral cavity of the offending biter, as well as the environment where the injury occurred. A variety of aerobic as well as anaerobic organisms have been isolated from bite wounds, with infection ranging from localized cellulitis to systemic dissemination, leading to severe disease ranging from abscess to bone and joint infection, to endocarditis and brain abscess. Immediate wound management, including recognition of the most commonly associated infectious pathogens, and judicious use of empiric antibiotics are crucial in providing the best care after a bite. Here, we discuss the common animal bite associated infections, and provide the most up to date information regarding their management.