A 52-year-old transient male comes into the ER of a large county hospital. He is pale, coughing and complains of chest pains. Upon physical examination, it is determined that he is both underweight and undernourished. He has a rapid respiratory rate of 38/minute, a temperature of 102.1oF and smells of alcohol. When the doctor listened to his lungs, rales were apparent. A chest x-ray revealed extensive consolidation in the lower left lobe of his lungs. This was accompanied by cavity formation.
The patient produced a bloody sputum which revealed encapsulated gram-negative rods and a large number of neutrophils. Cultures of the sputum for Streptococcus pneumoniae, Mycoplasma pneumoniae, and Legionella pneumoniae were all negative. Despite being given high doses of broad-spectrum antibiotics, the patient's condition deteriorated. He was intubated and put on a ventilator. Unfortunately, the patient became septic and died shortly after this.
1. What is the probable causative organism in this case and how did you come to this conclusion?
2. Why did antibiotic therapy fail in this case?
3. Can this disease be transmitted from person-to-person? If not, how is it transmitted?
4. Do other species of this organism cause respiratory tract disease?
5. How can this organism be differentiated from other members of the Enterobacteriaceae?