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Capnocytophaga canimorsus Sepsis Following a Minor Dog Bite to the Finger: Case Report
SCIENTIFIC ARTICLE
Capnocytophaga canimorsus Sepsis Following a Minor Dog Bite to the Finger: Case Report Nicolas J. Dedy, MD, PhD,* Sarah Coghill, MBBS,† Nanda Kumar S. Chandrashekar, MBBS,* Randy R. Bindra, MD*
Capnocytophaga canimorsus is a gram-negative bacillus present in the oral cavities of 22% to 74% of healthy dogs. Capnocytophaga canimorsus has unique virulence factors that enable it to evade the human immune system and cause life-threatening sepsis following a dog bite. We report a previously well 68-year-old woman who presented with septic shock and multiorgan failure following a seemingly minor dog bite to the finger. The patient required intensive care treatment, intravenous antibiotic therapy, and multiple surgical procedures including amputation of the affected finger. The septicemia and coagulopathy that ensued resulted in gangrene and amputation of additional fingers and toes. The purpose of this report is to raise awareness of this organism among hand surgeons when faced with a patient presenting in septic shock and minimal signs at the site of a dog bite. (J Hand Surg Am. 2016;41(1):81e84. Copyright Ó 2016 by the American Society for Surgery of the Hand. All rights reserved.) Key words Capnocytophagacanimorsus, dog bite, hand infection, hand bite, sepsis.
D
account for over 60% of all animal bites. More than 333,000 visits to U.S. emergency departments annually have been attributed to dog bites, 50% of which occurred in the domestic environment.2 The upper extremity is frequently affected, and hand injuries occur in 30% of cases.3,4 The superficial location of nerves, blood vessels, tendons, and small joints in the wrist and hand renders these structures vulnerable to injury.3,5 Moreover, bite wounds to the hand have been shown to be more susceptible to infection than those in other anatomical regions, in part owing to the presence of multiple closed spaces including tendon sheaths and fibrous septa in the fingertip and thenar and midpalmar spaces.5 Approximately 30% to 40% of all hand bites develop clinical infection, and over half of these are caused by dog and cat bites.1,6 Depending on OG BITES ARE COMMON INJURIES AND 1
From the *Department of Orthopaedic Surgery; and the †Department of Infectious Diseases, Gold Coast University Hospital, Southport, Australia. Received for publication September 16, 2015; accepted in revised form October 16, 2015. No benefits in any form have been received or will be received related directly or indirectly to the subject of this article. Corresponding author: Nicolas J. Dedy, MD, PhD, Department of Orthopaedic Surgery, Gold Coast University Hospital, 1 Hospital Blvd., Southport, QLD 4215, Australia; e-mail: [email protected]. 0363-5023/16/4101-0013$36.00/0 http://dx.doi.org/10.1016/j.jhsa.2015.10.011
the causative organism, infected bite wounds can manifest as abscesses or nonpurulent infections such as cellulitis.6 Multiple organisms typically cause canine bite infections. Pasteurella, Streptococcus, and Staphylococcus species are commonly isolated aerobic pathogens, and Fusobacterium and Bacteroides species are typical anaerobes.1,6 Other hand infections after animal bites include septic tenosynovitis, arthritis, and osteomyelitis.3,5 Disseminated infections with severe sepsis are rare.1 One pathogen that has been associated with life-threatening septicemia after dog bites is Capnocytophaga canimorsus, a fastidious gramnegative bacillus that colonizes the oral cavity of animals, particularly dogs and cats.1,7 Although C. canimorsus sepsis is rare, case-fatality rates have been reported to be 26% to 30% with mortality rates of 60% in patients presenting in septic shock.1 We describe a case of severe sepsis caused by C. canimorsus after a minor dog bite. The purpose of this case report is to raise awareness among hand surgeons about this organism when faced with a patient presenting with septic shock or rapid clinical deterioration after a dog bite. CASE REPORT A previously well 68-year-old woman was brought to the emergency department by ambulance. On arrival,
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the patient was in septic shock with multiorgan failure including acute respiratory distress, acute kidney injury, disseminated intravascular coagulation with purpura fulminans, and ischemic hepatitis. The only preexisting comorbidity was asthma. The patient was afebrile with a blood pressure of 65/35 mm Hg and a heart rate of 125 beats per minute. The arterial oxygen partial pressure was 23 mm Hg. Hemoglobin on admission was 133 g/L, white cell count was 5,100/ mm3 with 75% neutrophils, and the platelet count was 13,000/mm3. The patient was anuric with a glomerular filtration rate of 14 mL/min and serum creatinine of 282 mmol/L and coagulopathic with an International Normalized Ratio of 2.9 and an activated partial thromboplastin time of 110 seconds. The serum C-reactive protein was 415 mg/L. The patient had been bitten by a dog 3 days before and sustained a small wound over the proximal interphalangeal joint of her right index finger. She washed the wound with alcohol and antiseptic solution within hours of the incident. Approximately 36 hours after the bite, she developed myalgia and nausea. On the day of admission, she felt severely ill with vomiting, myalgia, and disorientation and noted dusky discoloration of the right index finger. The patient was promptly admitted to the intensive care unit and intubated; hemodialysis was started. Circulation was initially supported with noradrenaline, dobutamine, and vasopressin. Empirical antibiotic therapy with piperacillin-tazobactam and lincomycin intravenously was initiated after blood cultures had been obtained. After other sources of sepsis were excluded, the patient was taken to the operating room on the same day for exploration and debridement of the bite wound. The proximal interphalangeal joint was exposed and irrigated. There was no evidence of intraarticular penetration or injury or evidence of purulent material. Tissue cultures from the wound were obtained during surgery. A gram-negative bacillus was identified in the initial blood cultures after 23 hours of culture. After 7 days, the organism was confirmed as C. canimorsus (Fig. 1). Tissue cultures from the wound remained negative. With the patient still in critical condition, disarticulation of the finger at the metacarpophalangeal joint was performed the following day for source control. During subsequent days, vasopressors were weaned, and the patient was extubated and transferred to the medical ward. Lincomycin was discontinued. By this time, the patient had developed ischemic gangrene involving multiple fingertips and all toes, and during the following 3 weeks, she returned to the operating room 4 times for debridement of a necrotic skin flap covering J Hand Surg Am.
FIGURE 1: Light micrograph of Gram stain at 100 magnification shows slender Gram-negative bacilli isolated from the patient’s blood cultures, later identified as Capnocytophaga canimorsus. Scale reference, 100 mm.
the second metacarpal head, followed by an index ray amputation and finally a split thickness skin graft. Antibiotics were discontinued 3 weeks following admission. After 5 weeks, the patient had partially recovered her renal function and was able to ambulate on the ward with a walker. The split-thickness skin graft healed, and dry gangrene of the fingertips completely demarcated and was debrided. She was discharged from the hospital after 6 weeks. DISCUSSION In the present report, we describe the case of lifethreatening sepsis after a minor dog bite to the finger. The pathogen C. canimorsus was identified from blood cultures. Capnocytophaga canimorsus is a gramnegative bacillus that colonizes the oral cavities of healthy dogs and cats and in the 1970s was first associated with severe sepsis in humans after dog bites.1,7 Recognized risk factors for severe infection include hyposplenism, alcohol-induced liver disease, and immunocompromise, although in 40% of cases no risk factors were identified, as was the situation in this case.1,7 The incubation period ranges from 1 to 8 days, and the clinical presentation frequently includes fever, myalgia, abdominal pain, diarrhea, vomiting, malaise, dyspnea, and confusion.1,7 Disseminated intravascular coagulation with purpura, hemolytic uremic syndrome, acute respiratory distress, multiorgan failure, and gangrene of the extremities have been described in association with sepsis caused by this organism.1,7 The patient we described developed malaise, severe myalgia, and vomiting within 2 days of the dog bite and presented in septic shock a day later. There was no r
Vol. 41, January 2016
C. CANIMORSUS SEPSIS AFTER DOG BITE TO FINGER
cavities of healthy dogs.12e15 A possible explanation for this is that many potential C. canimorsus infections are likely prevented by the administration of prophylactic antibiotics to patients with animal bites. Widely accepted treatment algorithms for animal bite wounds comprise copious irrigation, surgical exploration and debridement of any contaminated and necrotic tissue if necessary, and removal of foreign bodies.1,16 Prophylactic administration of empirical antibiotics for 2 to 5 days, although controversial especially in small bites or scratches, has been shown to reduce the risk of infection in hand bites.17 International guidelines support the use of amoxicillinclavulanate as a first-line antimicrobial prophylaxis following cat and dog bites; doxycycline or clindamycin is recommended as alternatives for patients with immediate hypersensitivity to penicillins.18 Capnocytophaga canimorsus is sensitive to all of these antibiotics. Finally, a high level of suspicion in patients with hand bites who develop systemic illness is critical to prevent potential fatality. In particular, when reviewing a patient with a dog or cat bite, symptoms such as diffuse abdominal pain, nausea and vomiting, myalgia, and general malaise that started within a few days of the injury should prompt the treating surgeon to initiate antibiotic therapy, as described previously, to prevent fulminant C. canimorsus sepsis.
purulence or any spreading cellulitis or other signs of serious infection. Capnocytophaga canimorsus causes limited localized inflammation at the bite, resulting in a slow immune response to early infection.7 Some patients may present with more severe localized signs including cellulitis, purulent discharge, and lymphangitis, however, and these cases are usually treated with antibiotics, in which case they rarely progress to fulminant disease. Conversely, patients presenting with fulminant septicemia are more likely to have had minor preceding injuries; cases of severe disease have been described after dog scratches and licks.8e10 Capnocytophaga canimorsus prevents immune responses by the host because it inhibits the release of tumor necrosis factor and other proinflammatory proteins by infected macrophages.11 Moreover, C. canimorsus can evade the human immune system because it is resistant to killing by serum complement and polymorphonuclear leucocytes, which is likely due to the composition of its lipopolysaccharide structure.11 It has specific virulence factors that enable it to resist phagocytosis by macrophages and to persist intracellularly within leucocytes, resulting in extensive bacteraemia.7,11 In addition, C. canimorsus exhibits a surface sialidase that enables it to feed on amino sugars from host cells.11 In contrast to the PantonValentine leukocidin in methicillin-resistant Staphylococcus aureus, which is able to destroy human leucocytes, C. canimorsus does not possess any cytotoxic properties.11 Thus, the gangrene of finger tips and toes that developed in our patient were likely secondary causes of septic shock as well as high-dose vasopressor therapy rather than direct effects of C. canimorsus itself. Capnocytophaga canimorsus is relatively difficult to culture and may require up to 14 days to identify, emphasizing the importance of a detailed clinical history.1 In the case reported here, the diagnosis was made after 7 days of culture. Capnocytophaga canimorsus is sensitive to a range of antibiotics including penicillins, b-lactam-blactamase inhibitor combinations, third-generation cephalosporins, clindamycin, doxycycline, carbapenems, and chloramphenicol, whereas aminoglycosides, aztreonam, and trimethoprim have been shown to be less effective.1 Our patient was treated with piperacillin-tazobactam, which was continued for 3 weeks after the diagnosis was made. A total of 484 laboratory-documented cases of C. canimorsus sepsis have been reported since 1961, making it a comparatively rare condition.7 This is surprising, considering the reported high incidence of dog bites and the fact that C. canimorsus has a documented prevalence of 22% to 74% in the oral J Hand Surg Am.
83
REFERENCES 1. Oehler RL, Velez AP, Mizrachi M, Lamarche J, Gompf S. Biterelated and septic syndromes caused by cats and dogs. Lancet Infect Dis. 2009;9(7):439e447. 2. Weiss HB, Friedman DI, Coben JH. Incidence of dog bite injuries treated in emergency departments. JAMA. 1998;279(1):51e53. 3. Nygaard M, Dahlin LB. Dog bite injuries to the hand. J Plast Surg Hand Surg. 2011;45(2):96e101. 4. Ostanello F, Gherardi A, Caprioli A, La Placa L, Passini A, Prosperi S. Incidence of injuries caused by dogs and cats treated in emergency departments in a major Italian city. Emerg Med J. 2005;22(4):260e262. 5. Benson LS, Edwards SL, Schiff AP, Williams CS, Visotsky JL. Dog and cat bites to the hand: treatment and cost assessment. J Hand Surg Am. 2006;31(3):468e473. 6. Talan DA, Citron DM, Abrahamian FM, Moran GJ, Goldstein EJ. Bacteriologic analysis of infected dog and cat bites. Emergency Medicine Animal Bite Infection Study Group. N Engl J Med. 1999;340(2):85e92. 7. Butler T. Capnocytophaga canimorsus: an emerging cause of sepsis, meningitis, and post- splenectomy infection after dog bites. Eur J Clin Microbiol Infect Dis. 2015;34(7):1271e1280. 8. Popiel KY, Vinh DC. “Bobo-Newton syndrome”: An unwanted gift from man’s best friend. Can J Infect Dis Med Microbiol. 2013;24(4): 209e214. 9. Christiansen CB, Berg RM, Plovsing RR, Moller K. Two cases of infectious purpura fulminans and septic shock caused by Capnocytophaga canimorsus transmitted from dogs. Scand J Infect Dis. 2012;44(8):635e639.
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14. Mally M, Paroz C, Shin H, et al. Prevalence of Capnocytophaga canimorsus in dogs and occurrence of potential virulence factors. Microbes Infect. 2009;11(4):509e514. 15. Suzuki M, Kimura M, Imaoka K, Yamada A. Prevalence of Capnocytophaga canimorsus and Capnocytophaga cynodegmi in dogs and cats determined by using a newly established species-specific PCR. Vet Microbiol. 2010;144(1e2):172e176. 16. Morgan M, Palmer J. Dog bites. BMJ. 2007;334(7590):413e417. 17. Medeiros I, Saconato H. Antibiotic prophylaxis for mammalian bites. Cochrane Database Syst Rev. 2001;2:CD001738. 18. Stevens DL, Bisno AL, Chambers HF, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America. Clin Infect Dis. 2014;59(2):147e159.
10. Tierney DM, Strauss LP, Sanchez JL. Capnocytophaga canimorsus mycotic abdominal aortic aneurysm: why the mailman is afraid of dogs. J Clin Microbiol. 2006;44(2):649e651. 11. Shin H, Mally M, Meyer S, et al. Resistance of Capnocytophaga canimorsus to killing by human complement and polymorphonuclear leukocytes. Infect Immun. 2009;77(6):2262e2271. 12. Dilegge SK, Edgcomb VP, Leadbetter ER. Presence of the oral bacterium Capnocytophaga canimorsus in the tooth plaque of canines. Vet Microbiol. 2011;149(3e4):437e445. 13. van Dam AP, van Weert A, Harmanus C, Hovius KE, Claas EC, Reubsaet FA. Molecular characterization of Capnocytophaga canimorsus and other canine Capnocytophaga spp. and assessment by PCR of their frequencies in dogs. J Clin Microbiol. 2009;47(10): 3218e3225.
J Hand Surg Am.
r
Vol. 41, January 2016
Capnocytophaga canimorsus Sepsis Following a Minor Dog Bite to the Finger: Case Report Nicolas J. Dedy, MD, PhD,* Sarah Coghill, MBBS,† Nanda Kumar S. Chandrashekar, MBBS,* Randy R. Bindra, MD*
Capnocytophaga canimorsus is a gram-negative bacillus present in the oral cavities of 22% to 74% of healthy dogs. Capnocytophaga canimorsus has unique virulence factors that enable it to evade the human immune system and cause life-threatening sepsis following a dog bite. We report a previously well 68-year-old woman who presented with septic shock and multiorgan failure following a seemingly minor dog bite to the finger. The patient required intensive care treatment, intravenous antibiotic therapy, and multiple surgical procedures including amputation of the affected finger. The septicemia and coagulopathy that ensued resulted in gangrene and amputation of additional fingers and toes. The purpose of this report is to raise awareness of this organism among hand surgeons when faced with a patient presenting in septic shock and minimal signs at the site of a dog bite. (J Hand Surg Am. 2016;41(1):81e84. Copyright Ó 2016 by the American Society for Surgery of the Hand. All rights reserved.) Key words Capnocytophagacanimorsus, dog bite, hand infection, hand bite, sepsis.
D
account for over 60% of all animal bites. More than 333,000 visits to U.S. emergency departments annually have been attributed to dog bites, 50% of which occurred in the domestic environment.2 The upper extremity is frequently affected, and hand injuries occur in 30% of cases.3,4 The superficial location of nerves, blood vessels, tendons, and small joints in the wrist and hand renders these structures vulnerable to injury.3,5 Moreover, bite wounds to the hand have been shown to be more susceptible to infection than those in other anatomical regions, in part owing to the presence of multiple closed spaces including tendon sheaths and fibrous septa in the fingertip and thenar and midpalmar spaces.5 Approximately 30% to 40% of all hand bites develop clinical infection, and over half of these are caused by dog and cat bites.1,6 Depending on OG BITES ARE COMMON INJURIES AND 1
From the *Department of Orthopaedic Surgery; and the †Department of Infectious Diseases, Gold Coast University Hospital, Southport, Australia. Received for publication September 16, 2015; accepted in revised form October 16, 2015. No benefits in any form have been received or will be received related directly or indirectly to the subject of this article. Corresponding author: Nicolas J. Dedy, MD, PhD, Department of Orthopaedic Surgery, Gold Coast University Hospital, 1 Hospital Blvd., Southport, QLD 4215, Australia; e-mail: [email protected]. 0363-5023/16/4101-0013$36.00/0 http://dx.doi.org/10.1016/j.jhsa.2015.10.011
the causative organism, infected bite wounds can manifest as abscesses or nonpurulent infections such as cellulitis.6 Multiple organisms typically cause canine bite infections. Pasteurella, Streptococcus, and Staphylococcus species are commonly isolated aerobic pathogens, and Fusobacterium and Bacteroides species are typical anaerobes.1,6 Other hand infections after animal bites include septic tenosynovitis, arthritis, and osteomyelitis.3,5 Disseminated infections with severe sepsis are rare.1 One pathogen that has been associated with life-threatening septicemia after dog bites is Capnocytophaga canimorsus, a fastidious gramnegative bacillus that colonizes the oral cavity of animals, particularly dogs and cats.1,7 Although C. canimorsus sepsis is rare, case-fatality rates have been reported to be 26% to 30% with mortality rates of 60% in patients presenting in septic shock.1 We describe a case of severe sepsis caused by C. canimorsus after a minor dog bite. The purpose of this case report is to raise awareness among hand surgeons about this organism when faced with a patient presenting with septic shock or rapid clinical deterioration after a dog bite. CASE REPORT A previously well 68-year-old woman was brought to the emergency department by ambulance. On arrival,
Ó 2016 ASSH
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Published by Elsevier, Inc. All rights reserved.
r
81
82
C. CANIMORSUS SEPSIS AFTER DOG BITE TO FINGER
the patient was in septic shock with multiorgan failure including acute respiratory distress, acute kidney injury, disseminated intravascular coagulation with purpura fulminans, and ischemic hepatitis. The only preexisting comorbidity was asthma. The patient was afebrile with a blood pressure of 65/35 mm Hg and a heart rate of 125 beats per minute. The arterial oxygen partial pressure was 23 mm Hg. Hemoglobin on admission was 133 g/L, white cell count was 5,100/ mm3 with 75% neutrophils, and the platelet count was 13,000/mm3. The patient was anuric with a glomerular filtration rate of 14 mL/min and serum creatinine of 282 mmol/L and coagulopathic with an International Normalized Ratio of 2.9 and an activated partial thromboplastin time of 110 seconds. The serum C-reactive protein was 415 mg/L. The patient had been bitten by a dog 3 days before and sustained a small wound over the proximal interphalangeal joint of her right index finger. She washed the wound with alcohol and antiseptic solution within hours of the incident. Approximately 36 hours after the bite, she developed myalgia and nausea. On the day of admission, she felt severely ill with vomiting, myalgia, and disorientation and noted dusky discoloration of the right index finger. The patient was promptly admitted to the intensive care unit and intubated; hemodialysis was started. Circulation was initially supported with noradrenaline, dobutamine, and vasopressin. Empirical antibiotic therapy with piperacillin-tazobactam and lincomycin intravenously was initiated after blood cultures had been obtained. After other sources of sepsis were excluded, the patient was taken to the operating room on the same day for exploration and debridement of the bite wound. The proximal interphalangeal joint was exposed and irrigated. There was no evidence of intraarticular penetration or injury or evidence of purulent material. Tissue cultures from the wound were obtained during surgery. A gram-negative bacillus was identified in the initial blood cultures after 23 hours of culture. After 7 days, the organism was confirmed as C. canimorsus (Fig. 1). Tissue cultures from the wound remained negative. With the patient still in critical condition, disarticulation of the finger at the metacarpophalangeal joint was performed the following day for source control. During subsequent days, vasopressors were weaned, and the patient was extubated and transferred to the medical ward. Lincomycin was discontinued. By this time, the patient had developed ischemic gangrene involving multiple fingertips and all toes, and during the following 3 weeks, she returned to the operating room 4 times for debridement of a necrotic skin flap covering J Hand Surg Am.
FIGURE 1: Light micrograph of Gram stain at 100 magnification shows slender Gram-negative bacilli isolated from the patient’s blood cultures, later identified as Capnocytophaga canimorsus. Scale reference, 100 mm.
the second metacarpal head, followed by an index ray amputation and finally a split thickness skin graft. Antibiotics were discontinued 3 weeks following admission. After 5 weeks, the patient had partially recovered her renal function and was able to ambulate on the ward with a walker. The split-thickness skin graft healed, and dry gangrene of the fingertips completely demarcated and was debrided. She was discharged from the hospital after 6 weeks. DISCUSSION In the present report, we describe the case of lifethreatening sepsis after a minor dog bite to the finger. The pathogen C. canimorsus was identified from blood cultures. Capnocytophaga canimorsus is a gramnegative bacillus that colonizes the oral cavities of healthy dogs and cats and in the 1970s was first associated with severe sepsis in humans after dog bites.1,7 Recognized risk factors for severe infection include hyposplenism, alcohol-induced liver disease, and immunocompromise, although in 40% of cases no risk factors were identified, as was the situation in this case.1,7 The incubation period ranges from 1 to 8 days, and the clinical presentation frequently includes fever, myalgia, abdominal pain, diarrhea, vomiting, malaise, dyspnea, and confusion.1,7 Disseminated intravascular coagulation with purpura, hemolytic uremic syndrome, acute respiratory distress, multiorgan failure, and gangrene of the extremities have been described in association with sepsis caused by this organism.1,7 The patient we described developed malaise, severe myalgia, and vomiting within 2 days of the dog bite and presented in septic shock a day later. There was no r
Vol. 41, January 2016
C. CANIMORSUS SEPSIS AFTER DOG BITE TO FINGER
cavities of healthy dogs.12e15 A possible explanation for this is that many potential C. canimorsus infections are likely prevented by the administration of prophylactic antibiotics to patients with animal bites. Widely accepted treatment algorithms for animal bite wounds comprise copious irrigation, surgical exploration and debridement of any contaminated and necrotic tissue if necessary, and removal of foreign bodies.1,16 Prophylactic administration of empirical antibiotics for 2 to 5 days, although controversial especially in small bites or scratches, has been shown to reduce the risk of infection in hand bites.17 International guidelines support the use of amoxicillinclavulanate as a first-line antimicrobial prophylaxis following cat and dog bites; doxycycline or clindamycin is recommended as alternatives for patients with immediate hypersensitivity to penicillins.18 Capnocytophaga canimorsus is sensitive to all of these antibiotics. Finally, a high level of suspicion in patients with hand bites who develop systemic illness is critical to prevent potential fatality. In particular, when reviewing a patient with a dog or cat bite, symptoms such as diffuse abdominal pain, nausea and vomiting, myalgia, and general malaise that started within a few days of the injury should prompt the treating surgeon to initiate antibiotic therapy, as described previously, to prevent fulminant C. canimorsus sepsis.
purulence or any spreading cellulitis or other signs of serious infection. Capnocytophaga canimorsus causes limited localized inflammation at the bite, resulting in a slow immune response to early infection.7 Some patients may present with more severe localized signs including cellulitis, purulent discharge, and lymphangitis, however, and these cases are usually treated with antibiotics, in which case they rarely progress to fulminant disease. Conversely, patients presenting with fulminant septicemia are more likely to have had minor preceding injuries; cases of severe disease have been described after dog scratches and licks.8e10 Capnocytophaga canimorsus prevents immune responses by the host because it inhibits the release of tumor necrosis factor and other proinflammatory proteins by infected macrophages.11 Moreover, C. canimorsus can evade the human immune system because it is resistant to killing by serum complement and polymorphonuclear leucocytes, which is likely due to the composition of its lipopolysaccharide structure.11 It has specific virulence factors that enable it to resist phagocytosis by macrophages and to persist intracellularly within leucocytes, resulting in extensive bacteraemia.7,11 In addition, C. canimorsus exhibits a surface sialidase that enables it to feed on amino sugars from host cells.11 In contrast to the PantonValentine leukocidin in methicillin-resistant Staphylococcus aureus, which is able to destroy human leucocytes, C. canimorsus does not possess any cytotoxic properties.11 Thus, the gangrene of finger tips and toes that developed in our patient were likely secondary causes of septic shock as well as high-dose vasopressor therapy rather than direct effects of C. canimorsus itself. Capnocytophaga canimorsus is relatively difficult to culture and may require up to 14 days to identify, emphasizing the importance of a detailed clinical history.1 In the case reported here, the diagnosis was made after 7 days of culture. Capnocytophaga canimorsus is sensitive to a range of antibiotics including penicillins, b-lactam-blactamase inhibitor combinations, third-generation cephalosporins, clindamycin, doxycycline, carbapenems, and chloramphenicol, whereas aminoglycosides, aztreonam, and trimethoprim have been shown to be less effective.1 Our patient was treated with piperacillin-tazobactam, which was continued for 3 weeks after the diagnosis was made. A total of 484 laboratory-documented cases of C. canimorsus sepsis have been reported since 1961, making it a comparatively rare condition.7 This is surprising, considering the reported high incidence of dog bites and the fact that C. canimorsus has a documented prevalence of 22% to 74% in the oral J Hand Surg Am.
83
REFERENCES 1. Oehler RL, Velez AP, Mizrachi M, Lamarche J, Gompf S. Biterelated and septic syndromes caused by cats and dogs. Lancet Infect Dis. 2009;9(7):439e447. 2. Weiss HB, Friedman DI, Coben JH. Incidence of dog bite injuries treated in emergency departments. JAMA. 1998;279(1):51e53. 3. Nygaard M, Dahlin LB. Dog bite injuries to the hand. J Plast Surg Hand Surg. 2011;45(2):96e101. 4. Ostanello F, Gherardi A, Caprioli A, La Placa L, Passini A, Prosperi S. Incidence of injuries caused by dogs and cats treated in emergency departments in a major Italian city. Emerg Med J. 2005;22(4):260e262. 5. Benson LS, Edwards SL, Schiff AP, Williams CS, Visotsky JL. Dog and cat bites to the hand: treatment and cost assessment. J Hand Surg Am. 2006;31(3):468e473. 6. Talan DA, Citron DM, Abrahamian FM, Moran GJ, Goldstein EJ. Bacteriologic analysis of infected dog and cat bites. Emergency Medicine Animal Bite Infection Study Group. N Engl J Med. 1999;340(2):85e92. 7. Butler T. Capnocytophaga canimorsus: an emerging cause of sepsis, meningitis, and post- splenectomy infection after dog bites. Eur J Clin Microbiol Infect Dis. 2015;34(7):1271e1280. 8. Popiel KY, Vinh DC. “Bobo-Newton syndrome”: An unwanted gift from man’s best friend. Can J Infect Dis Med Microbiol. 2013;24(4): 209e214. 9. Christiansen CB, Berg RM, Plovsing RR, Moller K. Two cases of infectious purpura fulminans and septic shock caused by Capnocytophaga canimorsus transmitted from dogs. Scand J Infect Dis. 2012;44(8):635e639.
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C. CANIMORSUS SEPSIS AFTER DOG BITE TO FINGER
14. Mally M, Paroz C, Shin H, et al. Prevalence of Capnocytophaga canimorsus in dogs and occurrence of potential virulence factors. Microbes Infect. 2009;11(4):509e514. 15. Suzuki M, Kimura M, Imaoka K, Yamada A. Prevalence of Capnocytophaga canimorsus and Capnocytophaga cynodegmi in dogs and cats determined by using a newly established species-specific PCR. Vet Microbiol. 2010;144(1e2):172e176. 16. Morgan M, Palmer J. Dog bites. BMJ. 2007;334(7590):413e417. 17. Medeiros I, Saconato H. Antibiotic prophylaxis for mammalian bites. Cochrane Database Syst Rev. 2001;2:CD001738. 18. Stevens DL, Bisno AL, Chambers HF, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America. Clin Infect Dis. 2014;59(2):147e159.
10. Tierney DM, Strauss LP, Sanchez JL. Capnocytophaga canimorsus mycotic abdominal aortic aneurysm: why the mailman is afraid of dogs. J Clin Microbiol. 2006;44(2):649e651. 11. Shin H, Mally M, Meyer S, et al. Resistance of Capnocytophaga canimorsus to killing by human complement and polymorphonuclear leukocytes. Infect Immun. 2009;77(6):2262e2271. 12. Dilegge SK, Edgcomb VP, Leadbetter ER. Presence of the oral bacterium Capnocytophaga canimorsus in the tooth plaque of canines. Vet Microbiol. 2011;149(3e4):437e445. 13. van Dam AP, van Weert A, Harmanus C, Hovius KE, Claas EC, Reubsaet FA. Molecular characterization of Capnocytophaga canimorsus and other canine Capnocytophaga spp. and assessment by PCR of their frequencies in dogs. J Clin Microbiol. 2009;47(10): 3218e3225.
J Hand Surg Am.
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Vol. 41, January 2016