In the clinical laboratory, routine cultures may be held for insufficient time to grow nocardiae, and referral to a reference laboratory may be needed for species identification. Pulmonary infiltration and pleural effusion are usually detected via x-ray. Treatment
Nocardiosis requires at least 6 months of treatment, preferably with trimethoprim/sulfamethoxazole or high doses of sulfonamides. In patients who do not respond to sulfonamide treatment, other drugs, such as ampicillin, erythromycin, or minocycline, may be added.Treatment also includes surgical drainage of abscesses and excision of necrotic tissue. The acute phase requires complete bed rest; as the patient improves, activity can increase.A new combination drug therapy (sulfonamide, ceftriaxone, and amikacin) has also shown promise. Prognosis
The prognosis of nocardiosis is highly variable. The state of the hosts health, site, duration, and severity of the infection all play parts in determining the prognosis. Currently, skin and soft tissue infections have a 100% cure rate, and pleuropulmonary infections have a 90% cure rate with appropriate therapy. The cure rate falls to 63% with those infected with disseminated nocardiosis, with only half of patients surviving infections that cause brain abscess. Additionally, 44% of people who are infected in the central nervous system (CNS) die, increasing to 85% if that person has an already weakened immune system. There are no preventative treatments for nocardiosis. The only recommendation is to protect open wounds to limit entrance of the bacterium. Epidemiology
Although there are no international data available on worldwide infection rates per year, there are roughly 500–1000 documented cases of nocardiosis per year in the US.
Tachyphylaxis (Greek ταχύς, tachys, "rapid", and φύλαξις, phylaxis, "protection") is a medical term describing an acute, sudden decrease in response to a drug after its administration; i.e. a rapid and short-term onset of drug tolerance. It can occur after an initial dose or after a series of small doses. Increasing the dose of the drug may be able to restore the original response. Characteristics
Tachyphylaxis is characterized by the rate sensitivity: the response of the system depends on the rate with which a stimulus is presented. To be specific, a high-intensity prolonged stimulus or often-repeated stimulus may bring about a diminished response also known as desensitization. Molecular interaction
In biological sciences, molecular interactions are the physical bases of the operation of the system. The control of the operation, in general, involves interaction of a stimulus molecule with a receptor/enzyme subsystem by, typically, binding to the macromolecule A and causing an activation or an inhibition of the subsystem by forming an activated form of the macromolecule B.