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Rat bite fever in a pet lover
Rat bite fever in a pet lover Bari B. Cunningham, MD,a,b Amy S. Paller, MD,a,b and Ben Z. Katz, MDa,c Chicago, Illinois Rat bite fever is an uncommon bacterial illness resulting from infection with Streptobacillus moniliformis that is often transmitted by the bite of a rat. The cutaneous findings in rat bite fever are nonspecific but have been described as maculopapular or petechial. We describe a 9-year-old girl with acrally distributed hemorrhagic pustules, fever, and arthralgias. Diagnosis was delayed because of difficulty in identifying the pathologic organism. She was successfully treated with 10 days of ceftriaxone. (J Am Acad Dermatol 1998;38:330-2.)
Streptobacillus moniliformis is an uncommonly reported pathogen, usually associated with rat bite fever. We describe a 9-year-old girl with fever, malaise, arthralgias, and acrally distributed hemorrhagic pustules. The child had three pet rats at home but could not remember ever being bitten. Despite the history of rat exposure, diagnosis was delayed because of the difficulty in identifying the cause. CASE REPORT A 9-year-old girl had nausea, vomiting, fever to 40° C, and a painful lesion on her left heel for 2 weeks. The next day an asymptomatic eruption appeared on her lower extremities, accompanied by knee and elbow arthralgias and fatigue. She had traveled to rural Wisconsin several weeks before where she sustained multiple tick bites. She is a horseback rider and cares for three pet rats and a salamander. She recalled no rat bite, but did sustain several scratches. Examination revealed multiple tender, hemorrhagic pustules on her hands (Fig. 1), elbows, and heels (Fig. 2) bilaterally. Her right ankle was mildly edematous, but showed full range of motion. Complete blood count revealed a white count of 8500/mm3 with 80% neutrophils, 1 band, 15 lymphocytes, and 4 mononuclear cells, hemoglobin 11.6 gm/dl This article is made possible through an education grant from Ortho Dermatological. From the Departments of Pediatrics,a Dermatology,b and Infectious Diseases,c Northwestern University Medical School. Dr. Cunningham is a Johnson & Johnson Consumer Products, Inc. Fellow in Pediatric Dermatology. Reprint requests to: Amy S. Paller, MD, Division of Dermatology, #107, Children’s Memorial Hospital, 2300 Children’s Plaza, Chicago, IL 60614. E-mail: [email protected] Copyright © 1998 by The American Academy of Dermatology, Inc. 0190-9622/98/$5.00 + 0 16/4/85748
330
Fig. 1. Hemorrhagic pustule and erythematous macules on palm.
and platelets of 204,000/mm3. Electrolyte levels were normal. The Westergren erythrocyte sedimentation rate was 49mm/hour (normal 0 to 20). Ceftriaxone was administered intravenously. A biopsy specimen of a hemorrhagic pustule on the hand revealed a perivascular and periadnexal lymphohistiocytic infiltration with scattered neutrophils, but no vasculitis. Special stains (D-PAS, Gram, acid fast, and Warthin-Starry stain) showed no organisms. Cultures from the biopsy specimen for bacteria, fungi, and atypical mycobacteria were negative, as were cultures of urine and stool. After 5 days, in standard Bactec bottles using the Bactec system, blood cultures grew pinpoint colonies
Journal of the American Academy of Dermatology Volume 38, Number 2, Part 2
Cunningham, Paller, and Katz 331
Fig. 2. Hemorrhagic pustule with surrounding erythema on heel.
of a gram-negative bacillus, sensitive to vancomycin and resistant to aminoglycosides. The colonies were ultimately identified by the Centers for Disease Control and Prevention as S. moniliformis, and that they grew vigorously in 20% serum on heart infusion agar. A diagnosis of rat bite fever was made. The patient received a total of 10 days of intravenous ceftriaxone with resolution of arthralgias, fever, and cutaneous lesions. During the subsequent year, there was no evidence of recurrence. DISCUSSION
Rat bite fever is an uncommon bacterial illness that usually results from infection with S. moniliformis, a gram-negative organism often transmitted by the bite of a rat. A second organism, Spirillum minus, can cause a similar disease. In addition to its association with rats, cases have also been described after bites by a squirrel, mouse, weasel, or gerbil1 and, as in our patient, many cases occur without a history of a rat bite.2 Ten percent to 100% of healthy rats carry S. moniliformis in the nasopharynx,3 and the organism may be excreted in the urine.4 The disease most commonly occurs in laboratory personnel, inner city residents of low socioeconomic status, and children.5 More than half of the cases of rat bite fever in the United States occur in children.4 Patients typically have nonspecific features: fever, rash, and polyarthralgia or polyarthritis; the disease can mimic rheumatoid arthritis.6
Occasionally, the course is complicated by endocarditis, meningitis, myositis, abscesses, splenic or renal infarction, pericardial effusion, brain abscess, and sepsis; fatalities have been reported.7-11 The term rat bite fever encompasses three distinct clinical disorders caused by two organisms: (1) rat bite fever (“sodoku”) caused by S. minus; (2) streptobacillary rat bite fever caused by S. moniliformis; and (3) Haverhill fever, produced by S. moniliformis after the ingestion of milk contaminated by the oral secretions of infected rats.12 S. moniliformis is the primary cause of rat bite fever in the United States. It is a gram-negative pleomorphic rod that grows well under microaerophilic conditions. The bacterium can vary from long, wavy chains to filamentous structures with characteristic bulbous swellings. The organism requires media enriched with blood, serum, or ascitic fluid for growth; in our case, the isolate grew best in a medium enriched with 20% serum. The addition of even small amounts of the anticoagulant commonly found in blood culture tubes (sodium polyanethol sulfonate [Liquoid]) can interfere with the growth of S. moniliformis.13 In retrospect, the confusing situation of a gramnegative organism with a gram-positive antibiotic sensitivity pattern should have suggested the cause of the patient’s illness. There are subtle differences between the diseases caused by S. moniliformis and S. minus.
332 Cunningham, Paller, and Katz Arthritis is more common in disease caused by S. moniliformis, as was seen in our patient. S. minus is more likely to cause a local reaction at the site of the rodent bite, characterized by induration, tenderness, or ulceration.12 Finally, the two organisms have different average incubation periods: 5 days for S. moniliformis and 13 days for S. minus.14 Penicillin is generally considered the drug of choice for this infection, although penicillin-resistant strains of S. moniliformis have rarely been reported. Ampicillin, tetracycline, and second and third generation cephalosporins (e.g., cefuroxime and cefotaxime, respectively) are alternative agents.4 The diagnosis of rat bite fever is difficult microbiologically for several reasons: the fastidious growth requirements of the organism, the variable positivity of the gram stains, and the inconsistent bacterial structure. The diagnosis can be difficult clinically as well, for the differential diagnosis of a patient with polyarthropathy, fever, and acrally distributed hemorrhagic pustules is exhaustive and includes rheumatic diseases, vasculitis, and infection. An accurate exposure history is crucial. Alerting the bacteriology laboratory to this diagnostic possibility before culture will also aid in the recovery of the organism. We thank Robert Weaver from the Centers for Disease Control and Prevention for his help in isolating the organism and helpful discussions. We also thank Westwood-Squibb Pharmaceuticals for the cost of the color photographs. REFERENCES 1. Wilkins EG, Millar JG, Cockcroft PM, Okubadejo DA. Rat-bite fever in a gerbil breeder. J Infect 1988;16:17780.
Journal of the American Academy of Dermatology February 1998
2. Fordham JM, McKay-Ferguson E, Danes A, Blyth T. Rat bite fever without the bite. Ann Rheum Dis 1992; 51:711-2. 3. Wilson M. Profiles of infections. In: A world guide to infectious diseases, distribution, diagnosis. New York: Oxford University Press; 1991. p. 653-4. 4. Rubin LG. Streptobacillus moniliformis (rat-bite fever). In: Long SS, Pickering LL, Prober CG, editors. Principles and practice of pediatric infectious diseases. New York: Livingstone; 1997. p. 1046-7. 5. Raffin BJ, Freemark M. Streptobacillary rat-bite fever: a pediatric problem. Pediatrics 1979;64:214-7. 6. Holroyd KJ, Reiner AP, Dick JD. Streptobacillus moniliformis polyarthritis mimicking rheumatoid arthritis: an urban case of rat bite fever. Am J Med 1988;85:711-4. 7. Rupp ME. Streptobacillus moniliformis endocarditis: case report and review. Clin Infect Dis 1992;14:769-72. 8. Dijkmans BA, Thomeer RT, Vielvoye GJ, Lampe AS, Mattie H. Brain abscess due to Streptobacillus moniliformis and Actinobacterium meyerii. Infection 1984: 12(4):262-4. 9. Rygg M, Bruun CF. Rat bite fever (Steptobacillus moniliformis) with septicemia in a child. Scand J Infect Dis 1992;24:535-40. 10. Carbeck RB, Murphy JF, Britt EM. Streptobacillary ratbite fever with massive pericardial effusion. JAMA 1967;201(9):703-4. 11. McHugh TP, Bartlett RL, Raymond JI. Rat-bite fever: report of a fatal case. Ann Emerg Med 1985;14:1116-8. 12. Parker RH. Rat-bite fever. In: Hoeprick PD, Jordan MC, editors. Infectious diseases: a modern treatise of infectious processes. Philadelphia: Lippincott; 1989. p. 13102. 13. Lambe DW, McPhedran AM, Mertz JA, Stewart P. Streptobacillus moniliformis isolated from a case of Haverhill fever: biochemical characterization and inhibitory effect of sodium polyanethol sulfonate. Am J Clin Path 1973;60:854-60. 14. Mandel DR. Streptobacillary fever: an unusual cause of infectious arthritis. Cleve Clin Q 1985;52:203-5.
Streptobacillus moniliformis is an uncommonly reported pathogen, usually associated with rat bite fever. We describe a 9-year-old girl with fever, malaise, arthralgias, and acrally distributed hemorrhagic pustules. The child had three pet rats at home but could not remember ever being bitten. Despite the history of rat exposure, diagnosis was delayed because of the difficulty in identifying the cause. CASE REPORT A 9-year-old girl had nausea, vomiting, fever to 40° C, and a painful lesion on her left heel for 2 weeks. The next day an asymptomatic eruption appeared on her lower extremities, accompanied by knee and elbow arthralgias and fatigue. She had traveled to rural Wisconsin several weeks before where she sustained multiple tick bites. She is a horseback rider and cares for three pet rats and a salamander. She recalled no rat bite, but did sustain several scratches. Examination revealed multiple tender, hemorrhagic pustules on her hands (Fig. 1), elbows, and heels (Fig. 2) bilaterally. Her right ankle was mildly edematous, but showed full range of motion. Complete blood count revealed a white count of 8500/mm3 with 80% neutrophils, 1 band, 15 lymphocytes, and 4 mononuclear cells, hemoglobin 11.6 gm/dl This article is made possible through an education grant from Ortho Dermatological. From the Departments of Pediatrics,a Dermatology,b and Infectious Diseases,c Northwestern University Medical School. Dr. Cunningham is a Johnson & Johnson Consumer Products, Inc. Fellow in Pediatric Dermatology. Reprint requests to: Amy S. Paller, MD, Division of Dermatology, #107, Children’s Memorial Hospital, 2300 Children’s Plaza, Chicago, IL 60614. E-mail: [email protected] Copyright © 1998 by The American Academy of Dermatology, Inc. 0190-9622/98/$5.00 + 0 16/4/85748
330
Fig. 1. Hemorrhagic pustule and erythematous macules on palm.
and platelets of 204,000/mm3. Electrolyte levels were normal. The Westergren erythrocyte sedimentation rate was 49mm/hour (normal 0 to 20). Ceftriaxone was administered intravenously. A biopsy specimen of a hemorrhagic pustule on the hand revealed a perivascular and periadnexal lymphohistiocytic infiltration with scattered neutrophils, but no vasculitis. Special stains (D-PAS, Gram, acid fast, and Warthin-Starry stain) showed no organisms. Cultures from the biopsy specimen for bacteria, fungi, and atypical mycobacteria were negative, as were cultures of urine and stool. After 5 days, in standard Bactec bottles using the Bactec system, blood cultures grew pinpoint colonies
Journal of the American Academy of Dermatology Volume 38, Number 2, Part 2
Cunningham, Paller, and Katz 331
Fig. 2. Hemorrhagic pustule with surrounding erythema on heel.
of a gram-negative bacillus, sensitive to vancomycin and resistant to aminoglycosides. The colonies were ultimately identified by the Centers for Disease Control and Prevention as S. moniliformis, and that they grew vigorously in 20% serum on heart infusion agar. A diagnosis of rat bite fever was made. The patient received a total of 10 days of intravenous ceftriaxone with resolution of arthralgias, fever, and cutaneous lesions. During the subsequent year, there was no evidence of recurrence. DISCUSSION
Rat bite fever is an uncommon bacterial illness that usually results from infection with S. moniliformis, a gram-negative organism often transmitted by the bite of a rat. A second organism, Spirillum minus, can cause a similar disease. In addition to its association with rats, cases have also been described after bites by a squirrel, mouse, weasel, or gerbil1 and, as in our patient, many cases occur without a history of a rat bite.2 Ten percent to 100% of healthy rats carry S. moniliformis in the nasopharynx,3 and the organism may be excreted in the urine.4 The disease most commonly occurs in laboratory personnel, inner city residents of low socioeconomic status, and children.5 More than half of the cases of rat bite fever in the United States occur in children.4 Patients typically have nonspecific features: fever, rash, and polyarthralgia or polyarthritis; the disease can mimic rheumatoid arthritis.6
Occasionally, the course is complicated by endocarditis, meningitis, myositis, abscesses, splenic or renal infarction, pericardial effusion, brain abscess, and sepsis; fatalities have been reported.7-11 The term rat bite fever encompasses three distinct clinical disorders caused by two organisms: (1) rat bite fever (“sodoku”) caused by S. minus; (2) streptobacillary rat bite fever caused by S. moniliformis; and (3) Haverhill fever, produced by S. moniliformis after the ingestion of milk contaminated by the oral secretions of infected rats.12 S. moniliformis is the primary cause of rat bite fever in the United States. It is a gram-negative pleomorphic rod that grows well under microaerophilic conditions. The bacterium can vary from long, wavy chains to filamentous structures with characteristic bulbous swellings. The organism requires media enriched with blood, serum, or ascitic fluid for growth; in our case, the isolate grew best in a medium enriched with 20% serum. The addition of even small amounts of the anticoagulant commonly found in blood culture tubes (sodium polyanethol sulfonate [Liquoid]) can interfere with the growth of S. moniliformis.13 In retrospect, the confusing situation of a gramnegative organism with a gram-positive antibiotic sensitivity pattern should have suggested the cause of the patient’s illness. There are subtle differences between the diseases caused by S. moniliformis and S. minus.
332 Cunningham, Paller, and Katz Arthritis is more common in disease caused by S. moniliformis, as was seen in our patient. S. minus is more likely to cause a local reaction at the site of the rodent bite, characterized by induration, tenderness, or ulceration.12 Finally, the two organisms have different average incubation periods: 5 days for S. moniliformis and 13 days for S. minus.14 Penicillin is generally considered the drug of choice for this infection, although penicillin-resistant strains of S. moniliformis have rarely been reported. Ampicillin, tetracycline, and second and third generation cephalosporins (e.g., cefuroxime and cefotaxime, respectively) are alternative agents.4 The diagnosis of rat bite fever is difficult microbiologically for several reasons: the fastidious growth requirements of the organism, the variable positivity of the gram stains, and the inconsistent bacterial structure. The diagnosis can be difficult clinically as well, for the differential diagnosis of a patient with polyarthropathy, fever, and acrally distributed hemorrhagic pustules is exhaustive and includes rheumatic diseases, vasculitis, and infection. An accurate exposure history is crucial. Alerting the bacteriology laboratory to this diagnostic possibility before culture will also aid in the recovery of the organism. We thank Robert Weaver from the Centers for Disease Control and Prevention for his help in isolating the organism and helpful discussions. We also thank Westwood-Squibb Pharmaceuticals for the cost of the color photographs. REFERENCES 1. Wilkins EG, Millar JG, Cockcroft PM, Okubadejo DA. Rat-bite fever in a gerbil breeder. J Infect 1988;16:17780.
Journal of the American Academy of Dermatology February 1998
2. Fordham JM, McKay-Ferguson E, Danes A, Blyth T. Rat bite fever without the bite. Ann Rheum Dis 1992; 51:711-2. 3. Wilson M. Profiles of infections. In: A world guide to infectious diseases, distribution, diagnosis. New York: Oxford University Press; 1991. p. 653-4. 4. Rubin LG. Streptobacillus moniliformis (rat-bite fever). In: Long SS, Pickering LL, Prober CG, editors. Principles and practice of pediatric infectious diseases. New York: Livingstone; 1997. p. 1046-7. 5. Raffin BJ, Freemark M. Streptobacillary rat-bite fever: a pediatric problem. Pediatrics 1979;64:214-7. 6. Holroyd KJ, Reiner AP, Dick JD. Streptobacillus moniliformis polyarthritis mimicking rheumatoid arthritis: an urban case of rat bite fever. Am J Med 1988;85:711-4. 7. Rupp ME. Streptobacillus moniliformis endocarditis: case report and review. Clin Infect Dis 1992;14:769-72. 8. Dijkmans BA, Thomeer RT, Vielvoye GJ, Lampe AS, Mattie H. Brain abscess due to Streptobacillus moniliformis and Actinobacterium meyerii. Infection 1984: 12(4):262-4. 9. Rygg M, Bruun CF. Rat bite fever (Steptobacillus moniliformis) with septicemia in a child. Scand J Infect Dis 1992;24:535-40. 10. Carbeck RB, Murphy JF, Britt EM. Streptobacillary ratbite fever with massive pericardial effusion. JAMA 1967;201(9):703-4. 11. McHugh TP, Bartlett RL, Raymond JI. Rat-bite fever: report of a fatal case. Ann Emerg Med 1985;14:1116-8. 12. Parker RH. Rat-bite fever. In: Hoeprick PD, Jordan MC, editors. Infectious diseases: a modern treatise of infectious processes. Philadelphia: Lippincott; 1989. p. 13102. 13. Lambe DW, McPhedran AM, Mertz JA, Stewart P. Streptobacillus moniliformis isolated from a case of Haverhill fever: biochemical characterization and inhibitory effect of sodium polyanethol sulfonate. Am J Clin Path 1973;60:854-60. 14. Mandel DR. Streptobacillary fever: an unusual cause of infectious arthritis. Cleve Clin Q 1985;52:203-5.