The patient is a 42-year-old male with a history of left shoulder osteomyelitis with resistant Pseudomonas from an injury he sustained approximately 20 years ago.

which are prepositons and conjunctions?
? none?

This sentence has 4 prepositions.

Please check this site for a list of prepositions.

http://www.englishclub.com/grammar/prepositions-list.htm

You're right that there are no conjunctions in this sentence.

In the given sentence, there are no prepositions or conjunctions. Prepositions are words that show the relationship between a noun/pronoun and other words in a sentence, such as "in," "on," "at," "with," or "from." Conjunctions, on the other hand, are words that connect words, phrases, or clauses, such as "and," "but," "or," or "because."

In the provided sentence, the words "with" and "from" might be mistaken for prepositions at first glance, but in this context, they are used as part of the medical terminology to describe the type of infection and the source of the infection. So, they do not function as prepositions or conjunctions in the sentence.