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

Case Presentation

An 82-year-old African American woman presented to our emergency department with a 2-hour history of non-bilious, non-bloody vomiting, and one episode of loose stools. She later developed worsening shortness of breath and was found to be febrile to 39.7°C, pulse 104 beats/minute, blood pressure 169/71mmHg, respiratory rate of 18 breaths/minute and saturating 95% on room air. She was obese with body mass index 35 and her examination was significant only for some bibasilar crackles. She denied any travel history, contact with people who were ill, abdominal pain, chest pain or dysuria.

Her past medical history was significant for hypertension, hyperlipidemia, chronic obstructive pulmonary disease (COPD), coronary artery disease status post-coronary artery bypass, stroke, and breast cancer status post-chemotherapy and radiation therapy. Laboratory test results on admission were remarkable for white blood cell count (WBC) of 15,500, lactic acid of 2.5mmol/l, creatinine of 1.19mg/dl which was her baseline, and negative troponins. An electrocardiogram showed normal sinus rhythm. Computed tomography (CT) of her abdomen-pelvis was unremarkable. Her chest X-ray showed cardiomegaly with some pulmonary venous congestion. The suspicion for sepsis was high; however, the source was unclear at that time. Blood and urine cultures were sent, and on an empirical basis vancomycin and piperacillin-tazobactam were administered intravenously. Her lactic acid increased to 5mmol/l, creatinine to 2.28mg/dl and WBC to 27,000 in a few hours. She became hypotensive requiring pressor support and was admitted to our intensive care unit for possible septic shock. Overnight, she had a cardiopulmonary arrest with pulseless electrical activity and there was a return of spontaneous circulation after chest compressions and epinephrine in 5 minutes. She was intubated for hypoxic respiratory failure. Her arterial blood gas showed pH of 7.14, partial pressure of oxygen (pO 2) of 98mmHg, partial pressure of carbon dioxide (pCO 2) of 43mmHg and bicarbonate of 15mmol/l. She received alteplase and was started on heparin drip for possible pulmonary embolism. On the second day, two blood cultures grew non-motile Gram-negative rods and vancomycin was stopped. Due to the worsening respiratory status and suspicion for ventilator-associated pneumonia and extended-spectrum beta-lactamases, piperacillin-tazobactam was switched to imipenem-cilastatin. The colonies of the organism grew on blood and chocolate agar but not on MacConkey agar. The growth on blood agar was gray and non-hemolytic (Figs. 1 and 2).

Figure 1.

Grey non-hemolytic colonies of Pasteurella multocida on blood agar. Pasturella multocida is aerobic and facultative anaerobic and grows on blood agar, chocolate agar but not on MacConkey's agar. Most isolates are oxidase, indole and catalase positive

Figure 2.

Non-motile Gram-negative rods of Pasteurella. Gram-negative rods of Pasteurella as seen under the microscope

It was catalase, oxidase and indole positive and a RapID NH test (a qualitative test to identify species of Neisseria, Haemophilus and other related microorganisms isolated from humans) confirmed it as Pasteurella multocida. Her bronchial brush, sputum and urine cultures remained negative.

On careful examination, there were scratch marks and abrasions on her left leg. On further history, her daughter mentioned that her cat died a few days ago, and she bought another cat after that. We believe that the most likely route of transmission of Pasteurella infection was through the skin; however, another route could not be ruled out. She was eventually weaned off the pressors and was extubated after 7 days. The repeat blood cultures were negative. Her hospital course was complicated by hematemesis leading to aspiration, repeat cardiopulmonary arrest and re-intubation. At that time, she received steroids for possible COPD exacerbation. She also developed Clostridium difficile colitis, and was treated with oral vancomycin for 14 days. She was extubated successfully after 3 days, and was treated with imipenem-cilastatin for a total of 19 days for Pasteurella bacteremia and possible aspiration pneumonia. She was discharged after 25 days of hospitalization to a subacute rehabilitation center.

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