List the most likely pathogens which may be encountered in patients admitted with severe sepsis in the following clinical circumstances.

Clinical circumstance

Pathogen

Encephalitis following a flying fox bite

 

Gram  negative  sepsis  in  a  patient recently  returned  from  Papua  New Guinea during the wet season

 

Gram  negative  sepsis  in a patient  who has been on meropenem  for a week

 

Meningitis in a post splenectomy patient

 

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College Answer

Clinical circumstance

Pathogen

Encephalitis following a flying fox bite

Lyssa virus  or rabies virus or rhabdo virus

Gram  negative  sepsis  in  a  patient recently  returned  from  Papua  New Guinea during the wet season

Melioidosis / Acinetobacter

Gram  negative  sepsis  in a patient  who has been on meropenem  for a week

Stenotrophomonas or multi- resistant pseudomonas or acinetobacter

Meningitis in a post splenectomy patient

Pneumo or meningococcus,

Discussion

This is another game of "Name That Microbe".

Flying foxes carry Lyssavirus, which resembles rabies and can completely destroy your brain.

It takes little imagination to surmise that PNG during the rainy season is not exactly a sterile place to be. However, I shamefully confess I had no idea what the endemic gram-negatives look like. Fortunately, a Google Scholar search for the string "papua new guinea gram negative rainy season" yielded this article on melioidosis as the first result. In short, it is a dangerous predominantly pulmonary infection by Burkholderia pseudomallei.

The patient who has been marinading in meropenem will likely have an ESBL meropenem-resistant gram negative bug - probably something from the Enterobacteriaceae family. Potential candidates include Enterobacter, StenotrophomonasCitrobacterAcinetobacterSerratiaAchromobacter and so on and so forth.

Meningitis in the asplenic person is likely due to an encapsulated organism - and statistially speaking, this is most likely going to be S. pneumoniae, although N.meningitides or H.influenzae are also potential culprits.

References

Fraser, Graeme C., et al. "Encephalitis caused by a Lyssavirus in fruit bats in Australia." Emerging infectious diseases 2.4 (1996): 327.

 

Currie, Bart J., et al. "The epidemiology of melioidosis in Australia and Papua New Guinea." Acta tropica 74.2 (2000): 121-127.