More detailed identification techniques involve the culture of infectious agents isolated from a patient. Culture allows identification of infectious organisms by examining their microscopic features, by detecting the presence of substances produced by pathogens, and by directly identifying an organism by its genotype. Other techniques (such as X-rays, CAT scans, PET scans or NMR) are used to produce images of internal abnormalities resulting from the growth of an infectious agent. The images are useful in detection of, for example, a bone abscess or a spongiform encephalopathy produced by a prion. Symptomatic diagnostics
The diagnosis is aided by the presenting symptoms in any individual with an infectious disease, yet it usually needs additional diagnostic techniques to confirm the suspicion. Some signs are specifically characteristic and indicative of a disease and are called pathognomonic signs; but these are rare. Not all infections are symptomatic.In children the presence of cyanosis, rapid breathing, poor peripheral perfusion, or a petechial rash increases the risk of a serious infection by greater than 5 fold. Other important indicators include parental concern, clinical instinct, and temperature greater than 40 °C. Microbial culture
Many diagnostic approaches depend on microbiological culture to isolate a pathogen from the appropriate clinical specimen. In a microbial culture, a growth medium is provided for a specific agent. A sample taken from potentially diseased tissue or fluid is then tested for the presence of an infectious agent able to grow within that medium.
Nafcillin sodium is a narrow-spectrum beta-lactam antibiotic of the penicillin class. As a beta-lactamase-resistant penicillin, it is used to treat infections caused by Gram-positive bacteria, in particular, species of staphylococci that are resistant to other penicillins. Nafcillin is considered therapeutically equivalent to oxacillin, although one retrospective study found greater rates of hypokalemia and acute kidney injury in patients taking nafcillin compared to patients taking oxacillin. Indications
Nafcillin is indicated in the treatment of staphylococcal infections, except those caused by MRSA.U.S. clinical practice guidelines recommend either nafcillin or oxacillin as the first-line treatment of choice for staphylococcal endocarditis in patients without artificial heart valves. Side-effects
As with all penicillins, serious life-threatening allergic reactions can occur.Milder side-effects include:

Hypokalemia
Nausea and vomiting
Diarrhea, often due to suppression of normal gastrointestinal bacteria, which, on occasion, leads to a more serious super-infection with an organism like Clostridium difficile
Abdominal pain
Yeast infections (thrush) affecting the mouth and tongue or vagina
Agranulocytosis, neutropenia

Interactions
There is evidence that nafcillin induces cytochrome P-450 enzymes, specifically CYP2C9. Several drugs with a narrow therapeutic window, such as warfarin and nifedipine, are metabolized by CYP2C9.Nafcillin contains salts added as stability media. These added salts could cause edema or fluid accumulation. It would be prudent to avoid this medication if there were a concern for a congestive heart failure or kidney disease. == References ==