Las Vegas Sun

March 29, 2024

5-MINUTE EXPERT:

Your body is full of bacteria — and that’s not a bad thing

Grossology

Steve Marcus

A model of bacteria at a smell display at “Grossology: The (Impolite) Science of the Human Body” in the Lied Discovery Children’s Museum Monday, June 8, 2009. This is the bacteria behind “mouth” smell, or bad breath. The exhibition uses animatronics and interactive elements to teach kids about runny noses, body odors and other inner workings of the human body. In other words, farts, burps, boogers and snot.

FAQ: What are prebiotics and probiotics?

• Probiotics are “good” bacteria found in foods and supplements. They can aid digestion, protect against more dangerous bacteria and restore populations of good bacteria.

• Prebiotics are carbohydrates that can’t be digested by the human body and remain as food for probiotics. They are found in food and can be taken as supplements.

Q: Should I take prebiotics and probiotics?

Some doctors recommend taking a course of probiotics with antibiotics to ensure that “bad” bacteria are killed and “good” bacteria are replenished, but probiotics aren’t required for good health.

Q: What foods contain prebiotics and probiotics?

Prebiotics can be found in whole grains, bananas, onions, garlic, honey and artichokes.

Probiotics are found in yogurt, kefir, fermented cheese, miso soup, kimchi and other foods.

Did you know?

Bacteria account for 2 to 6 pounds of a 200-pound person’s body weight.

We spend much of our lives trying to avoid bacteria — washing our hands, squirting hand sanitizer and taking courses of antibiotics. But what about the countless bacteria that live within us every day?

As it turns out, we’re actually more bacteria than we are human. At any given time, there are 10 times as many bacterial cells in our bodies as human ones. The bacteria help us digest food, produce chemicals we need to live and protect us from harmful bacteria. Still, the same bacteria that keep us alive also wield the power to hurt us.

Take, for example, the bacteria found in our colons. They help us extract nutrients from food. But if those bacteria found their way into a vital organ or our bloodstream, they could cause a serious infection.

“Microbiology associated with humans has evolved quite a lot,” UNLV life sciences professor Brian Hedlund said. “It used to be very much focused on microbes one at a time, but lately they’ve been changing to a holistic or systems-level approach. There are diseased states or healthy states, communities of microbes that are healthy or not.”

In the world of bacteria, it’s hard to call one bacteria entirely good or bad. Truth is, a bacteria’s character often comes down to one factor: location.

Nose

Staphylococcus aureus: Though a significant cause of infections, S. aureus frequently is found living in the nose. An estimated 86.9 million people in the United States — about a third of the population — carry S. aureus. The bacterium can cause skin infections known as staph infections that can range from mild to life-threatening. The superbug MRSA is a drug-resistant strain of this bacterium. MRSA stands for Methicillin-resistant Staphylococcus aureus.

Mouth

The mouth is home to a diverse population of bacteria that can change over the course of a lifetime. Certain bacteria prefer to live in specific parts of the mouth, such as the tongue, cheek, palate or teeth. Many help prevent colonization by other, more harmful bacteria. The mouth protects itself against bacteria by maintaining its mucous membranes and enamel. Species include Streptococcus, Haemophilus, Veillonella and Prevotella.

Skin

Skin teems with bacteria, though they’re not visible to the naked eye.

Staphylococcus epidermidis: S. epidermidis is the most common bacterium found on human skin cells. It generally is harmless or even good for humans, as it protects us from more harmful bacteria by producing substances that are toxic to other bacteria. Also, studies have shown S. epidermidis may help signal an immune response to invaders. That said, if S. epidermidis gets inside the body, such as entering by way of a catheter or implant, it can cause infection.

Moraxella species: These bacteria commonly are found on skin and mucous membranes, particularly in the upper respiratory tract. They typically cause infection when defensive barriers break down, allowing the bacteria to invade.

Propionibacterium acnes: This bacterium is the culprit behind acne, formally “acne vulgaris,” which affects up to 80 percent of adolescents in the United States. The bacterium also is prevalent on healthy skin; some scientists say it may protect skin. However, it can cause postoperative infections.

Stomach

Not too many bacteria call the stomach home because stomach acid makes it a relatively unpleasant environment. Stomachs have the most bacteria right after a meal but typically undetectable amounts after digestion.

Helicobacter pylori: Many peptic ulcers in the stomach or small intestine are caused by H. pylori, which is found in 30 to 40 percent of Americans. The bacterium is more common in developing countries, where it infects about 70 percent of people. Chronic H. pylori infections can result in an increased chance of stomach cancer. Still, some studies have examined a correlation between the disappearance of H. pylori and an increase in childhood asthma, infant diarrhea and esophageal disease.

Small intestine

Food moves quickly through the small intestine, usually in about three to five hours, which means bacteria tend to wash through quickly as well. Commonly found bacteria in the small intestine include streptococci, lactobacilli and bacteria from the Bacteroides species.

Lactobacillus acidophilus: In addition to aiding digestion by breaking down carbohydrates, this bacterium, found in yogurt and fermented soy products, produces vitamin K and lactase. It is one of the most commonly used probiotics.

Large intestine (colon)

The colon is home to about 500 species of bacteria and has the largest concentration of bacteria in the body. Everybody has a unique colony of bacteria in his or her intestines. Bacteria in the colon help break down food that humans otherwise would not be able to digest and help us produce vitamin K, vitamin B-12 and folic acid. Diet can influence colon bacteria.

Like skin bacteria, intestinal bacteria help prevent infections from more harmful bacteria. Taking antibiotics can disrupt the normal activities of the bacteria.

Common colon bacteria:

• Streptococcus

• Staphylococcus

• Corynebacterium

• Lactobacillus

• Enterococcus

• Enterobacteriaceae

• Eubacterium

• Clostridium

• Proteus

• Bacteroides

• Prevotella

• Escherichia coli (E. coli)

Vagina and urinary tract

The most common bacteria found here include lactobacilli, streptococci, staphylococci and corynebacteria. Lactobacilli are by far the most prevalent bacteria in the vagina; they account for more than 95 percent of all bacteria found there and tend to serve a protective role, producing substances that lower the pH of the vagina and keep other bacteria out. The urethra also is home to a small number of bacteria.

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