Pseudomonis Arg. is found EVERYWHERE, it's all over our bodies as it lives on our skin, and all over the bodies of all mammals, birds, repties, etc. If you were to take a swab of your bird's body, your own body, your dog's body, etc., and prepare a streak plate or do a Gram-Stain and look at it under a microscope, there are several strains of Staph and Strep along with the Pseudomonis and a few other bacterial strains that you would see in large quantities on every single swab...Typically our immune systems fight-off these commonly found bacterial strains when the opportunity arises for them to get into our bloodstreams, for example when we cut ourselves...Some people/animals have issues with their immune systems that cause them to constantly be contracting Staph, Strep, and Pseudomonis infections all the time because they are just everywhere, including all over us, and it can be a real issue...
Now I'm going to assume that your Avian Vet took a swab of your bird's mouth/beak/throat (wherever he swabbed, these are all the same thing for this purpose), and they either did a Gram-Stain and looked t it under their microscope right there is their office, or they sent the swab out to the lab they use for testing and had them plate it for a Culture & Sensitivity, or they did both, and the reason that they thought that your bird needed to be put onto an antibiotic was because his "Load" of Psedomonis Arg. was much higher than it should have been, which is very thorough of your Avian Vet to do, because most Vets would never think to do a swab of a bird's mouth/beak during a wellness-exam (even most of the best Certified Avian Vets don't do this), unless the bird was having some kind of issue eating or had stopped eating, or they had some kind of discharge coming from their mouth/beak, or they had visible sores, bleeding, etc. inside of their mouth or on their tongue...You're going to expect to find Pseudomonis Arg. inside of any bird's mouth, any person's mouth, etc., along with other commonly-found bacteria of the body...But it's the Bacterial-Load of these that would cause a Vet/Medical Doctor to become alarmed and prescribe an antibiotic...
***What antibiotic did your Vet prescribe to your bird? I don't know why they would prescibe an antibiotic the way that your Vet did though, that is what puzzles me...Usually the course of treatment for a high-load of Pseudomis Arg. would be either one antibiotic injection that continues working for 7 days, or for 10 days, and then you have another swab taken to do a re-check to make sure the Pseudomonis Arg. load has gone down to normal numbers (or depending on what part of the body we're talking about, that the Pseudomonis Arg. is totally gone, as it is not common in say the bloodstream, obviously, or in certain other tissue-samples or fluid -samples)...OR they could prescribe an oral-course of a few different antibiotics for either once a day for 7 days, or once a day for 10 days, OR another antibiotic that could be used is given by one injection that lasts for 7 days and then they also give an different oral antibiotic that the bird would take once or twice a day for the next 14 days...So there are many different antibiotics they could be using to treat a high-load of Pseudomonis in your bird's mouth, and each one has a different Route of Administration and length of dose, but I don't know of any that would be given by-injection once a day for 10 days in a row Now that doesn't mean it's not correct, I'm not a Vet and I don't do any continuing-education like they have to, so there may be a new way they're treating this that I'm not aware of...But from my point of view, why make the bird get an injection of antibiotics every day for 10 days to treat a bacterial infection when the same bacterial infection is successfully treated on a regular basis with a single-injection of another antibiotic? (Unless the patient is allergic to the other antibiotic options) But again, your Vet had a reason I'm sure, so as long as your bird is doing alright with the injections and with the antibiotic, and isn't getting sick from it or developing any signs/symptoms of an allergy, then it's all good...
***Just out of curiosity and for my own education, was your bird showing any signs/symptoms of being sick in-regards to his mouth/beak/throat, like his appetite had slowed and he wasn't eating much, or you saw anything wrong inside of his mouth, around his mouth, on his tongue etc., or any discharge or blood coming from his mouth, etc.? I'm just wondering if there are more and more Avian Vets doing a mouth-culture as a part of a regular Wellness-Exam now, or if your bird was actually showing signs of a problem and that's why your Vet took the culture....(I've been the Medical Liaison at a private Avian/Reptile Rescue for a little over 8 years, and I work with the CAV and the Certified Herp/Reptile Vet that we use; I am the one that does all of the Intake-Exams on the birds when they are first surrendered/brought in to the Rescue, as well as the regular Wellness-Exams of the residents who have been with us long-term, and I run the first Fecal microscopy/Floats right there and send-out any cultures that need to be run, I do the blood-draws and send them out, etc. So I'm just wondering if doing a mouth/beak/throat swab and running a Gram-Stain is something that CAV's are doing now regularly as a part of a basic Wellness-Exam...I'll talk to my CAV about this and see what he says too, because I don't see the benefit honestly unless the bird is having a problem or sign/symptom of a mouth/throat/sinus/Upper-Respiratory issues, just because you're going to find LOTS of different bacteria inside of their mouths, beak, on the back of their throat, throughout their sinuses, in their saliva and any mucous/sputum, etc. And Pseudomonis Arg. is one that you're always find, along with others...But if there is a benefit to doing it and if CAV's have started doing it as a part of their regular Wellness-Exams, then I'm very interested to know about...)
to an Avian vet. Her last visit to a vet was about 15 years ago. The only reason why I brought her to the vet was that I hadn’t in years, and I had the money and time. The doctor took blood, everything was good, her weight is normal and he did an oral culture and found out she has a bacterial infection called Pseud. aeruginosa. 
