In a warfare scenario, rapidly progressive pneumonia with gram-stained sputum showing gram-negative coccobacilli suggests a differential diagnosis of which of the following?

The presence of rapidly progressive pneumonia accompanied by gram-stained sputum that reveals gram-negative coccobacilli strongly indicates infections caused by certain pathogens associated with biological threats. Pneumonic plague, tularemia, and melioidosis are all characterized by similar clinical presentations.

Pneumonic plague, caused by Yersinia pestis, typically presents with severe pneumonia and can be rapidly progressive, which fits the description of the scenario. Tularemia, caused by Francisella tularensis, can also lead to pneumonia and is associated with gram-negative coccobacilli. Moreover, melioidosis, caused by Burkholderia pseudomallei, is another microbial infection that can manifest with pneumonia and is known for its ability to cause severe respiratory illness.

The other options involve diseases that do not typically present with the specific clinical and microbiological characteristics described. For instance, brucellosis and anthrax might cause pneumonia but do not usually present with gram-negative coccobacilli in sputum. Cholera, tetanus, and rabies are not associated with pneumonia in the context provided. Finally, smallpox, Ebola, and Hantavirus are not consistent with the gram-negative coccobacilli finding in sput