How do I know if the results are bad or OK

Not sure what you are asking or stating (from the wording).

as far as i know, when you say that there is 'infiltrates' it could mean that there is 'hazziness' in the lung fields. the lung fields of course has unilateral and bilateral xray and may be further divided by the lobes (Upper lobe, middle lobe or lower lobe) left or right which all in all could be indicative of a lung problem. if it is infiltrates, it could be indicative of pneumonia, so check if there is rusty colored sputum, difficulty of breathing, increase in wbc or segmenters in the cbc.

for culture and sensitivity, you have either gram negative or gram positive organisms... when you say gram negative it could be a number of organisms example, Pseudomonas spp, Serratia spp and the like. for gram positive it could be Staphylococcus spp or Streptococcus spp.

as far as i know the gram negative organisms are harder to kill than that of the gram positive organisms especially if it is Pseudomonal in nature because you will be needing an antibiotic with Pseudomonal coverage.

hopefully this could help. maybe a person with that result needs rest, antibiotic and time to recuperate.

It sounds like the patient might have pneumonia and a gram neg infection. They may need to be placed on resp. isolation and get IV ABTx for this.
Infiltrates can mean different things to different docs. Sounds like it needs to be monitored due to the bld cx.