Septic Shock Due to Pasteurella multocida Bacteremia: A Case Report

Niyati Narsana; Faria Farhat

Disclosures

J Med Case Reports. 2015;9(159) 

In This Article

Discussion

Pasteurella infections in humans commonly result from contact with animals such as cats, dogs, swine, lions, panthers, horses, rats, rabbits, and wolves.[4–6] It is a common commensal organism found in the oropharynx. Cats and dogs have a colonization rate of approximately 70 to 90% and 20 to 50% respectively.[4,6,7] Animal bites and scratches are the most common modes of acquisition of infection in humans. Cases of infection without any animal exposure have also been reported.[4,8]

Pasteurella is a non-motile aerobe and facultative anaerobe, which grows on chocolate and blood agar, but not on MacConkey agar. Pasteurella multocida does not cause hemolysis on blood agar, and grows in carbon dioxide-rich medium at 37°C.[4,5]

It can involve skin and soft tissue, bone and joint, upper and lower respiratory tract, and cause more severe infections such as meningitis, bacteremia, endocarditis and peritonitis. Local cutaneous infections are the most common.[5,9,10] In a study by Escande and Lion, bacteremia was found in 11% of 958 cases of Pasteurella infections.[10] In a study by Ebright et al. at Detroit Medical Center, 7.8% of 179 patients had positive blood cultures.[9] The various sources of isolation of this organism reported in the literature are local wounds, sputum, bronchoalveolar lavage, cerebrospinal, pleural, ascitic and joint fluid.[5,9,10] There are many cases where the source of bacteremia is unknown.[10,11] Our patient had the organism isolated only from her blood and the possible route of entry was a cat scratch. However, other possible routes of entry such as the respiratory tract could not be confirmed as bronchial brush cultures were negative.

Pasteurella infections are more common in elderly patients with underlying chronic diseases such as diabetes mellitus, hypertension, cardiac disease, acquired immunodeficiency syndrome (AIDS), malignancies, COPD, cirrhosis and dialysis.[9,10,12] The study by Escande and Lion showed 70% of systemic infections in ages >50 years and 21% in ages 20 to 50 years.[10] Our patient had multiple comorbidities including hypertension, hyperlipidemia, COPD and coronary artery disease which made her more susceptible to developing this severe infection.

Most of the studies have shown susceptibility of Pasteurella multocida to penicillins, beta-lactams, carbapenems, second and third generation cephalosporins and tetracyclines.[5,12–14] Severe systemic infections are treated with intravenous antibiotics and local infections with oral agents.[9,10] Studies have shown a mortality ranging from 7 to 31% in patients with Pasteurella bacteremia.[9–11]

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