Antibiotic overuse is a contributing factor to the creation of multidrug-resistant bacteria, informally called ‘super bugs’: relatively harmless bacteria can develop resistance to multiple antibiotics and cause life-threatening infections. Though antibiotics are required to treat severe bacterial infections, misuse has contributed to a rise in bacterial resistance. The overuse of fluoroquinolone (a family of antibiotics) and other antibiotics fuels antibiotic resistance in bacteria, which can inhibit the treatment antibiotic-resistant infections. Their excessive use in children with otitis media (ear infection) has given rise to a breed of bacteria resistant to antibiotics entirely.
Widespread use of fluoroquinolones as a first-line antibiotic has led to decreased antibiotic sensitivity, with negative implications for serious bacterial infections such as those associated with cystic fibrosis, where quinolones are among the few viable antibiotics. Antibiotics have no effect on viral infections such as the common cold. They are also ineffective against sore throats, which are usually viral and self-resolving. Most cases of bronchitis (90–95%) are viral as well, passing after a few weeks—the use of antibiotics such as ofloxacin against bronchitis is superfluous and can put the patient at risk of suffering adverse reactions.
In a 1994 study of fluoroquinolone issued in a long-term care setting, 75% of the examined prescriptions were judged to be inappropriate. Antibiotics can cause severe reactions, increasing hospitalization. Adverse effects from antibiotics account for nearly 25% of all adverse drug reactions amongst hospitalized patients. Negative reactions to fluoroquinolones are easily misdiagnosed as a seizure disorder, CNS problems, or psychiatric problems. In Italy, doctors report fluoroquinolones among the top three prescribed drugs responsible for adverse neurological and psychiatric effects. The neuropsychiatric effects include tremor, confusion, anxiety, insomnia, agitation, and psychosis (in severe cases). Among the quinolones, moxifloxacin is reported as having the highest propensity to cause CNS toxicity.
The use of fluoroquinolones as first-line agents is not generally recommended, except for patients who are seriously ill and may soon require hospitalization. However, the use of fluoroquinolones had increased three-fold in emergency rooms in the United States between 1995 and 2002, while the use of safer alternatives such as macrolides declined significantly. Patients with chronic prostatitis (inflamed prostate) are often misdiagnosed as having bacterial forms of prostatitis and are erroneously treated with fluoroquinolone. Only 5% of patients with prostatitis have bacterial prostatitis, which can alleviated by antibiotics.
There has been massive use of antibiotics in animal husbandry. Historically this use has been poorly regulated. In the United States the danger of emergence of antibiotic-resistant bacterial strains due to wide use of antibiotics to promote weight gain in livestock was determined by the FDA in 1977, but nothing effective was done to prevent the practice. In 2012, a District Court for the Southern District of New York, ruling in an action brought by the Natural Resources Defense Council (an environmental advocacy group) and others, ordered the FDA to revoke approvals for the use of antibiotics in livestock which violated FDA regulations.