Understanding Bronchitis: A Doctor Answers Your FAQs

Antibiotic Resistance, Mutation Rates And MRSA

As worrisome as MRSA is, it is just the tip of the iceberg, so to speak. In fact, there are a number of far more threatening drug-resistant bacteria in existence, such as Pseudomonas aeruginosa. P. Aeruginosa poses a greater threat because it has certain biological features that make it more readily resistant to antibiotics than MRSA. For example, P. Aeruginosa has a highly impermeable outer membrane, whereas MRSA does not. This outer membrane makes it more difficult for antibiotic chemical compounds to actually get inside the bacterial cell so that they can inflict damage. Moreover, once the antibiotic compounds are inside it, P. Aeruginosa has what are known as efflux pumps, which can very quickly pump foreign compounds like antibiotics back out of the cell before they have a chance to do damage. MRSA does not have efflux pumps. Because of these biological features, P. Aeruginosa infections either quickly evolve multidrug resistance or are drug-resistant from the start. Unlike with MRSA, however, the likelihood of picking up a P. Aeruginosa infection from a doorknob in a school building is practically nil. P. Aeruginosa infections occur mostly among hospital patients—at least for now.

In both the hospital and the community, antibiotic resistance has emerged as a major public health problem. In fact, some scientists consider it the most important public health problem of the twenty-first century. The problem exists not just because bacterial mutation rates lead to a rapid accumulation of mutations (including drug-resistant mutations), but also because of the selective pressures that antibiotics impose. If a drug-resistant phenotype were to evolve and there were no antibiotic present, then that phenotype would fare no better than any other bacterial phenotype. In other words, it wouldn't flourish, and it might even die out. It is only when antibiotics are used that drug-resistant phenotypes have a selective advantage and survive.

Of course, not all mutations confer resistance, and most probably have nothing at all to do with resistance. That said, bacterial populations with especially high mutation rates (so-called "hypermutable" strains) often have higher antibiotic resistance rates. For example, in a study of cystic fibrosis (CF) patients infected with P. Aeruginosa (which is a major cause of sickness and death among CF patients), where more than a third of all CF patients had hypermutable P. Aeruginosa infections, the hypermutable populations had higher resistance rates than isolates with "normal" mutation rates (Oliver et al., 2000). Plus, there are other ways that bacteria evolve resistance, in addition to spontaneous nucleotide base mutations. For instance, bacteria can acquire resistance genes through conjugation (i.E., from plasmid DNA) and from recombination with other bacterial DNA following transformation.

The emergence and spread of antibiotic resistance has become such an important public health problem that many federal and state public health agencies now distribute educational posters to encourage "good hygiene" practices—practices that prevent the spread of antibiotic-resistant bacteria from one person to another and help keep those mutant S. Aureus bacteria off doorknobs. Maybe you have seen one of these posters in a school hallway, in a locker room, or in a public bathroom, imploring you to wash your hands with soap and water to help prevent disease.

To make MRSA matters even worse, in 2002, health care workers reported the first cases of vancomycin-resistant MRSA. In other words, even "last-resort" vancomycin doesn't always work. Therein lies the crisis: People are dying from "simple" bacterial infections, all because of a very low mutation rate.

Urgent Care Doctor Discusses Winter Virus Treatment, Why Antibiotics Aren't Prescribed

FULTON — A variety of viruses are circulating across Northeast Mississippi this winter, and their treatment differs from bacterial infections.

Dr. John Cantrell, an urgent care doctor at the Fulton Medical Clinic, spent 25 years as an emergency room physician. He said, when it comes to upper respiratory viruses, the only viruses the clinic specifically tests for are flu, COVID-19 and RSV.

"If you test negative for those and otherwise have viral-type symptoms, it's just a viral upper respiratory infection," Cantrell said. "There's no reason to test for a specific virus because the treatment is the same."

That treatment entails addressing individual symptoms while a person's immune system fights the virus. Antihistamines, decongestants, cough suppressants and steroids may be prescribed, but with a viral infection, antibiotics are not.

Antibiotic medications are unnecessary and ineffective at treating viruses, and are instead reserved for treating suspected bacterial infections like sinusitis and bronchitis.

The over-prescription of antibiotics can lead to bacteria's increased resistance to antibiotics, making them less effective over time.

"People have heard of the bad staph infections, and that's what's happened," Cantrell said. "Staph, in particular, certain strains of it, have been exposed to so many antibiotics that we've killed all but the ones the antibiotics don't effect. Those reproduce and now a lot of the staph is resistant to antibiotics."

In determining whether a patient has a viral or bacterial infection, diagnosis is mostly based on clinical examination — how a patient's lungs sound, whether their sinuses are tender, etc.

Once a viral infection is confirmed, the best advice doctors can offer is to be patient while the patient's body does the rest.

"Your body's immune system is going to have to take care of it," Cantrell said. "The medicines you're prescribed are to help make the symptoms more tolerable while your body's immune system is going to work."

When it comes to preventing viral infections in the winter, simple things like covering your mouth when you sneeze or cough, distancing yourself from people who are sick and frequent hand washing are important.

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