Hello there, I am dr.milan an infectious disease specialist answering your question. I think you have identified klebsiella is a good thing. And so you have taken antibiotic according to that culture & sensitivity report, but still you are not completely free of it. So now you need to do culture report again when you have symptoms of sinus infection by a reliable Microbiology lab and by a qualified Microbiologist MD Doctor. It might some other organism or organism with different sensitivity pattern. If infection is treated according to culture report than it must be resolve. Here it is not done completely. So might you have not taken drug for complete duration. So my advise for you to go for investigation suggested and follow the sensitivity report under guidance of your physician for comple duration suggested by him. Hope i have given appropriate guidance to you. if you have any query you can consult me anytime. Give me star rating, helpful vote & thank you according to your satisfaction level. Thanking you.