Hi J.,
It can be very difficult to differentiate infection from large scale inflammation in some cases, so it is possible that you're just dealing with the inflammation. But, it's also quite possible that the bacteria causing the infection are resistant to the antibiotic the doctor has prescribed. Hospital-aquired antibiotic resistant bacteria are on the rise -- not just the well publicized MRSA, but many other organisms.
I suggest you return to the doctor and request a change of antibiotics ASAP. If the wound is still open at all, or is weepy or pussing, the doctor should culture the site for the bacteria causing the infection and should also have the bacterial culture tested for antibiotic sensitivity so that an effective antibiotic will be prescribed. Also, that fluid you're seeing is an indication of an extensive (normal) immune response to the infection. The immune response itself can be very harmful if it becomes systemic and over-exuberant. Talk to your doctor about taking an antiinflamatory, such as ibuprofen, to help quell this response.
At the same time, it would be a good idea for the doctor to take a swab of your nasal nares. There is a preponderance of evidence in the medical literature showing that this is the primary reservoir for MRSA, and that patients who carry the organism in their nares are likely infected with it elsewhere, especially at the site of surgical incisions. If you do have a MRSA infection, make sure your doctor understands that this organism is not just resistant to methicillin. It is resistant to all antibiotics ending in cillin or penem, beginning with ceph, and aztreonam. BTW, keflex (also marketed under the names Panixine, Biocef, and Zartan) is often the drug of choice for skin infections. Its generic name is cephalexin and MRSA is resistant to it. Cyclines, such as tetracycline, and sulfa drugs work very well to combat most strains of MRSA.
Not to scare you, but there is some risk of severe sepsis and septic shock with abdominal incisions. If you find that you are very thirsty, dizzy, your pain is increasing and your urine output is reduced for the amount of fluid you're drinking, get to an ER immediately and demand appropriate attention. Express your concerns about the nonhealing infection of an abdominal incision. If you feel you're not being treated seriously, direct the ER staff to survivingsepsis.com and ask them to download the treatment bundles.
I hope you feel better soon!