DEAR DR. DONOHUE: In my state on the Gulf of Mexico, a distinguished citizen was infected with a bacterium called Vibrio vulnificus after swimming during a fishing trip.

The infection quickly developed into a flesh-eating one. He had had an almost-healed ulcer on his lower leg when he went swimming.

Eventually the germ entered his bloodstream. He was quite ill. What about our mouths? If we have a sore inside our mouth, should we be rinsing with mouthwash so no germs can enter the blood? Or if we burn a finger and later mess with plants, will bacteria enter? – O.N.

ANSWER: Even the ocean’s salty water is home to bacteria.

Vibrio vulnificus is one such bacterium. It thrives on salt and causes two different illnesses.

One is the kind you describe. The bacterium enters the skin through a break in it, even a trivial one. It spreads rapidly, causing the skin to redden, swell and become discolored.

Tissue dies. It looks like the flesh-eating infection, but it’s not exactly the same. (The flesh-eating bacterium is a strep bacterium.) Immediate treatment with antibiotics can halt its course, but it still carries a death rate of 25 percent.

The second Vibrio vulnificus is a digestive-tract infection most often brought on by eating raw oysters contaminated with it. The germ gains access to the blood and leads to fever, chills and a drop in blood pressure. From the blood, it reaches the skin, where it causes blisters that eventually form ulcers. This infection has a fatality of 50 percent.

We live in a world of germs. That shouldn’t upset you. These germs have lived among humans forever and ever. Humans manage to survive quite well in spite of them.

Only a few organisms are great troublemakers, and sensible precautions can protect us from most of those invaders. A person does not have to always swish germicidal washes in the mouth or do more than keep an open wound clean and bandaged to survive deadly but rare infections.

DEAR DR. DONOHUE: I am 90 years old. My bladder is falling. Can a stitch be put in down there to hold it up?

How far out can it come? I don’t want surgery, at my age. – M.B.

ANSWER: Several stitches can be put in down there to close the vagina. That stops the bladder (and the uterus, which often drops with it) from protruding outside the vagina.

You also can be fitted with a special pessary to prop up the bladder. A pessary is a device inserted into the vagina to hold falling organs in place.

When both bladder and uterus drop, a donut-shaped pessary fits onto the neck of the uterus to keep both organs where they should be. If only the bladder drops, a pessary with a slightly different shape can support it.

Bladders and uteruses drop because their supporting ligaments weaken with age. A fallen bladder – a cystocele (SIS-toe-seal) – can make women lose control of urine. The bladder can fall right through the vagina and be exposed to the outside.

DEAR DR. DONOHUE: A friend of mine told me about her son being on dialysis. His grandmother had the same problem and passed it to her grandson through his mother. The mother called the condition Alport’s syndrome. I have never heard of it. I can’t find it in the medical dictionary.

Tell me something about this condition, please. – G.H.

ANSWER: Alport’s syndrome is inherited. Its early signs are blood (often visible only with a microscope) in the urine, along with protein.

In 85 percent of Alport’s patients, the defective gene is on the X chromosome.

Women have two X chromosomes, so their good X chromosome can negate the effects of the bad one, and they don’t usually have severe symptoms.

Men, with only one X chromosome, frequently end up with severe kidney problems and have to undergo kidney dialysis or a kidney transplant.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com