The growing ineffectiveness of a popular and widely requested antibiotic has local doctors emphasizing the importance of responsible antibiotic use.

Chattanooga physicians say between one-half and two-thirds of the most-common bacteria - streptococcus pneumoniae - is showing resistance to azithromycin, the generic name for the antibiotic Zithromax. The antibiotic often is dispensed in a packet called the "Z-pak."

Streptococcus pneumoniae is an important germ because it is the No. 1 bacterial cause of pneumonia, bronchitis, sinusitis, ear infections and even meningitis, said Dr. Mark Anderson, an infectious disease specialist.

"It's not that (the Z-pak) has become a totally useless antibiotic, but it just makes us worry when the most common bug is becoming increasingly resistant," he said.

The more widely an antibiotic is used, the more likely pathogens in the environment - either bacteria that are infecting people or those that occur naturally on our bodies - get exposed to the treatment and build up resistance, doctors said. Those bacteria end up surviving and become increasingly common.

"You don't want to scare people, but at the same time, people should be aware" of growing antibiotic resistance, said Dr. Teresa Baysden, family medicine doctor with Chattanooga Primary Care. "We expect there will be bugs we have absolutely no antibiotics for in the next five to 10 years."

Easy to take and with few side effects, the Z-pak is extremely popular, and many patients request - or demand - it by name.

"There's a high patient demand for it," said Dr. Siobhan Duff, primary care physician with Chattanooga Family Practice. "People know it by name. It's snazzy; it's jazzy. A lot of people will tell us, 'It's the only thing that works for me.'"


Antibiotics are effective only in treating bacterial illnesses, not sicknesses caused by viruses. Viral infections that should not be treated with an antibiotic include:

* Colds

* Flu

* Most coughs and bronchitis

* Sore throats (except for those resulting from strep throat)

* Some ear infections

Source: U.S. Centers for Disease Control and Prevention


* Fever of at least 101.5 degrees

* Respiratory symptoms that are not preceded by a sore throat, congestion and runny nose (which would signify a cold)

* Coughing up phlegm that is darker than yellow or whitish

* Sudden onset of symptoms

Source: Dr. Mark Anderson, infectious disease specialist

Doctors admit they share responsibility for ensuring proper use of antibiotics. But physicians can find themselves in a difficult position when patients who may have only a cold or the flu insist upon a prescription. The Tennessee Department of Health estimates that between one-third and one-half of all antibiotic prescriptions are unnecessary.

"I do try to be more responsible but, man, it is hard," Dr. Baysden said. "The reason they come to me is that they want a pill."

Colds and flu bugs are viral - not bacterial - and therefore are not treatable with antibiotics.

Lab test are not always able to confirm the presence of a bacterial infection, and most inappropriate antibiotic prescriptions are given to patients who actually have a virus, said Lauri Hicks, medical director for the U.S. Centers for Disease Control and Prevention's Get Smart program. The program aims to educate patients and physicians about responsible antibiotic use.

"Widely Ineffective"

The first antibiotic, penicillin, was discovered in 1927. Penicillin revolutionized medicine in the 1940s, significantly reducing death from infectious diseases, according to the CDC.

Since the mid-1980s, though, bacteria have developed growing resistance to the drug.

"Penicillins are becoming more widely ineffective against the more-resistant bacteria," Dr. Baysden said. "When these bugs pick up new traits and they're able to fool the antibiotics, we're pretty much without that silver bullet that we were provided in the '40s and '50s that led us to believe we could fight anything."

Since the effectiveness of azithromycin is so questionable now, some doctors are avoiding prescribing the drug, fearing that a bacterial infection could worsen in the time it takes to discover the Z-pak isn't working.

"You're playing Russian roulette as a physician" if you prescribe it, Dr. Duff said.

Patients can do their part by taking antibiotics correctly and listening to their doctors when they say an antibiotic isn't necessary, Dr. Baysden said.

Incorrect use of an antibiotic - such as stopping a medication before all bacteria are killed off - means that surviving bacteria live on with a resistance to the drugs they have encountered, doctors say. Even if the patient feels better, those resistant bacteria can multiply and spread to others in their environment.

"It's more for respect of the community than for your own health that you should not inappropriately take antibiotics," Dr. Duff said.