Capnocytophaga canimorsus Infection in a 38-Year-Old Male after a Dog Bite

Here, we present a unique case of a 38-year-old male with a history of alcohol use disorder and multiple sexual partners, who presented with fulminant sepsis with shock, multiorgan failure, and livedo racemosa after a dog bite the week prior. The patient was intubated on arrival and was started on vasopressors and antibiotics. Eventually, the patient's clinical status improved, and he was transferred out of the intensive care unit. Blood cultures tested positive for oxidase-positive Gram-negative rods two days after collection, and species identification showed Capnocytophaga canimorsus.


Case Report
Tis patient is a 38-year-old male who was admitted for rapid onset acute hypoxic respiratory failure, requiring intubation.He had a past medical history of alcohol use disorder and multiple sexual partners.On the day of admission, he had nausea and vomiting as well as multiple episodes of diarrhea.He was cyanotic and had shortness of breath.
On examination, he had livedo racemosa on both lower extremities (Figure 1).He also had gangrene on his toes (Figure 2).He was in cardiogenic and septic shock (Table 1).Further workup showed acute liver failure and acute tubular necrosis requiring continuous renal replacement therapy (CRRT), DIC, and blood loss anemia (Table 2).He was treated supportively for DIC.
Initial treatment included vancomycin, meropenem, doxycycline, and ampicillin-sulbactam for broad spectrum coverage.Patient's sepsis and lactic acidosis continued to worsen despite treatment.Ten, micafungin was initiated to cover for fungal etiologies.Ten, blood cultures grew Gramnegative oxidase-positive rods.Matrix-assisted laser desorption/ionization time-of-fight mass spectrometry (MALDI-TOF MS) was used to identify the bacteria as Capnocytophaga canimorsus.Furthermore, peripheral blood smear showed intracellular rod-shaped bacteria (Figure 8).Meropenem was continued while all the other antimicrobials were stopped.Clindamycin was added.Te patient was weaned of vasopressors and clinically improved.

Discussion and Review of the Literature
In this section, we will discuss the risk factors for infection with Capnocytophaga and its association with livedo racemosa [9,10].We will also discuss diagnostic modalities.
In a study of thirty-nine cases of Capnocytophaga in Denmark, six people had a history of alcohol use disorder, like our patient [2].Alcohol abuse, cirrhosis, and asplenia are risk factors for infection with Capnocytophaga canimorsus [2,3].Our patient had no risk factors for being immunocompromised other than his history of alcohol use disorder.None of the literature reviewed suggested that having multiple sexual partners increased risk of infection.
Another interesting, though rare, feature of Capnocytophaga is its association with livedo racemosa.Capnocytophaga infection should be suspected in a patient who presents with signs of infection after a recent dog bite and has livedo racemosa, which can present before multiorgan failure [9,10].
Livedo racemosa can be confused with livedo reticularis since they look similar.Both types of rashes present as violaceous net-like patterns on the skin [11].In contrast to livedo reticularis, however, livedo racemosa is segmented, irregular, circular, and broken [11].Skin is one of the earliest    2 Case Reports in Infectious Diseases organs Capnocytophaga seems to infect [9].Moreover, livedo racemosa is irreversible in warm temperatures, while livedo reticularis is only present in cold temperatures [9].Unlike livedo reticularis, livedo racemosa is not only present on the extremities but also on the buttocks and trunk [11].
Identifying livedo racemosa can assist with early diagnosis of infection with Capnocytophaga, leading to early management.Giving antibiotics early has been shown by an observation study to improve outcomes [1].As mentioned earlier, we utilized meropenem and clindamycin.Beta-lactamase-and carbapenemase-resistant strains are susceptible to clindamycin [6,14].Rapidly diagnosing Capnocytophaga     is difcult since it requires a longer time to grow on blood cultures, averaging about six days to test positive [7].Tese bacteria appear as long fusiform Gram-negative rods on blood cultures and evade the immune system by inhibiting phagocytosis by macrophages and killing by polymorphonuclear leukocytes [15][16][17][18][19][20].
Polymerase chain reaction (PCR) and nanopore sequencing in whole blood may be other modalities that can be utilized for more rapid diagnosis in the future; are not available for clinical use yet [21][22][23].Peripheral blood smear is another way to expedite diagnosis, as it shows Capnocytophaga in the polymorphonuclear leukocytes [24].

Conclusion
Capnocytophaga canimorsus should be high on the diferential when a person develops severe sepsis with multiorgan dysfunction and DIC after a dog bite, especially if he is immunocompromised [1][2][3][4][5][6][7][8].It is important to be able to identify livedo racemosa and be able to distinguish it from livedo reticularis and purpura fulminans [11,13].Livedo racemosa, when present on exam, can provide a strong clue that the patient is infected with Capnocytophaga.
Finding Gram-negative rods intracellularly in the peripheral blood smear is yet another clue to help identify Capnocytophaga [24].Moreover, blood PCR can possibly identify DNA sequences belonging to Capnocytophaga; this could possibly expedite diagnosis if they were clinically available [21][22][23].Te peripheral blood smears and CT scan were taken from hospital records of the patient.Te photographs show the patient's extremities.

Figure 1 :
Figure 1: Livedo racemosa is present on the patient's legs.

Figure 2 :
Figure 2: Te patient had distal necrosis of the toes.

Figure 3 :
Figure 3: Te red lines are pointing towards bilateral pleural effusions.Te blue lines are pointing towards hypointense densities, which indicate bilateral atelectasis.

Figure 4 :
Figure 4: A subcapsular hematoma is present on the anterolateral aspects of the spleen.

Figure 8 :
Figure 8: Capnocytophaga canimorsus is a Gram-negative rod, seen in the polymorphonuclear leukocytes on this image.