I did the whole "probiotic thing" during and post my antibiotic treatment, still ended up with what my MD has classified as "chronic fungal disease". Which is resistant to many typical antifungals especially Nilstatin.
Dr John Chia has found only a small percentage of his patients actually benefit from antibiotics(aside from treating SIBO associated with EV infection)as only a small percentage have mycoplasma/chlamydia pneumoniae infections.
You may find you have bacterial biofilm within your sinuses if this is a chronic problem? You should try antibiofilm nasal washes in combination to your oral antibiotics.
I didnt mention it but once in awhile i will do a course of one of the systemic antifungals like nizoral. I actually dont have gut issues but do the things ive mentioned as a preventative.
For biofilms i have used the beg nasal spray which has helped for longer periods of time than abx themselves. Recently have also used diluted antiseptics which have helped just like the beg spray or bactroban spray where i have had longer periods off abx after use. Thats all along with regular saline sinus irrigation.
We came to the conclusion several years back that my sinus issues are from my chronic moderate neutropenia, after several scans and extensive immune tests.
So it can take awhile to dive deep and sort out sinuses.
Fungal treatments for me a preventative measure. Augmentin, bactrim and doxycycline on occassions help treat the bacterial infection along with the different sinus sprays ive used.
My dr has said swabs are inaccurate as one cant reach deep into the sinuses unless one drills through the forehead into the frontal sinuses but research that he has seen and has been involved in, is that in many its usually some sort of staph infection or even mrsa , which explains why the abx i mention have helped. Because these abx are a broad spectrum and can also kill a variety of bugs, bactrim is well known for killing community acquired MRSA.
My neutropenia is probably from a combination of things, one actually being a chronic bacterial infection like sinusitis but also chronic viral infections i have ie cmv, varicella, ebv and the low nk function would also indirectly effect neutrophils.
Just my opinion but reoccurring bacterial sinusitis issues in cfsme are so common because of the poor immune function. So like HIV they are susceptible many different coinfections because of their crappy immune system, so are cfsers.