A fatal pasteurella empyema

In August, 2013, a 60-year-old man from Honolulu with a history of hypertension, hyperlipidaemia, and 30 packyears of smoking was admitted to our hospital after cardiac arrest. He had a 4 week history of body aches and cough productive of yellow sputum, but denied fever, chest pain, night sweats, rash, recent travel, or sick contacts. He had not received infl uenza or pneumovax prophylaxis. On the day of admission he suddenly became unwell with acute dyspnoea and diaphoresis, developing agonal respiration in the car on the way to hospital. Emergency Medical Services arrived to fi nd that the patient was in pulseless electrical activity (PEA) arrest. Spontaneous circulation returned after 5 min of cardiopulmonary resuscitation, and the patient was intubated and taken to the emergency department. On arrival, he was unresponsive and hypotensive with sinus tachycardia, decreased breath sounds on the right, scattered rhonchi on the left, and equal but thready pulses throughout. Electrocardiogram (ECG) and cardiac markers were normal, but he had a raised white cell count with neutrophilia and a lactic acidosis of 8·3 mmoL/L. Chest radiograph showed near total right hemithorax opacifi cation. He was admitted to the Intensive Care Unit for presumed septic shock and started on metronidazole and cefepime, but because of haemodynamic instability he was not put on post-arrest hypothermic protocol. Chest CT showed widespread consolidation of the right lung with a 12 × 12 × 22 cm fl uid-air collection in the posterior hemithorax (fi gure). Fluid from an ultrasound-guided thoracentesis grew Gram-negative rods. He developed acute respiratory distress syndrome (ARDS) needing escalation of ventilatory support, with worsening hypoxia and acidosis (arterial blood gas pH 7·18, PaCO2 68, PaO2 41, HCO3 25) despite maximum medical therapy, and he died. The pleural fl uid later grew Pasteurella multocida. On discussion with his family we learnt he cared for several feral cats, which slept in his bed. An empyema typically develops adjacent to bacterial pneumonia and is the most complicated type of parapneumonic eff usion. In a study of US hospital admissions the admission rate for empyema-related diagnoses almost doubled between 1996 and 2008. The progression of an isolated empyema depends on underlying risk factors, with a morbidity and mortality rate between 10 and 50%. ARDS is often the fi nal result of both pulmonary and non-pulmonary illnesses. The most common pathogen isolated in empyema is Streptococcus pneumoniae (20–50%). Staphylococcus aureus, Pseudomonas, Klebsiella, and anaerobic bacteria make up most of the remainder. P multocida is a Gram-negative coccobacillus and zoonotic microbe found in the oral fl ora of cats (70%), dogs, and other mammals. It is often associated with soft tissue infections after cat bites; however, people can be colonised, with the potential for human-to-human spread. The lungs are an unusual site for P multocida colonisation, although transmission is related to inhalation of contaminated aerosols or inoculation with animal secretions. Underlying chronic pulmonary diseases can predispose patients to infection. The progression of P multocida pleuropulmonary infections is often non-specifi c, presenting with gradualonset subjective fever, sinusitis, bronchitis, or pneumonia. In patients with empyema and ARDS a history enquiring about previous animal contact can help guide appropriate treatment.