Are bacterial infections worse for children and the elderly

Yes, at extreme ages. Very young patients and very old patients both have trouble fighting off infections, for various reasons. That means their doctors prefer to do more tests, do tests sooner, and get treatment started earlier, so that infections have less of a chance to "take hold and spread".
Yes. For very young children (up to about 18 mos) and the elderly, bacterial infections can be far more severe than in healthy children over that age and in adults.

Related Questions

Are bacterial infections worse for a newborn?

Depends on germ/kid. The newborn represents a problem because of exposure to germs in a specialized way. The bag of waters surrounds baby & keeps germs out during pregnancy but when open, the birth canal may allow moms poop germs to climb into the babies area and attach. Later they may dig in and grow fast without showing signs. By the time baby seems sick (gbs) the infection may be so far along that nothing will help.
Depends. Bacterial infections are bad. When they get into the brain, blood etc. It can be very bad. The problem is that in newborns you don't always see the signs that something bad is going on like you would see in someone older, so you don't always know whether a newborn is very sick or a little sick, so we wind up treating sick newborns as if they have something life threatening until we know they don't.

I've been sick for going on 6 weeks. Went to ER. Told me I had a bacterial infection. Gave me tetracycline for ten days. I'm still sick worse.

Continuous care. You needed more than a trip to the ER. You needed to be monitored by a Physician. Obviously your antibiotic was ineffective. You may need a different antibiotic or another course of the Tetracycline. See a GP, Urgent Care, or return to the ER. But don't expect one visit treatment. Make sure you'd recovery is monitored.

Ways to prevent yeast infection or a bacterial infection at your vagina? Does it help if I don't wear underwear when I sleep or does it make it worse?

Diagnosis & treatmen. The key to recurrent vaginal discharge cure is diligence. Careful testing should be done each episode to make sure you know what you ate treating. With diligence recurrent discharge can almost always be treated. You need to find an obgyn willing to be patient and work with you. Sleeping in underwear is not relevant one way or the other.
Does not matter. Maintaining a healthy vaginal flora and ph is the best way to avoid overgrowth with unwanted bacteria, like yeast or a mix of anaerobic bacteria, that cause bacterial vaginosis. You should avoid vaginal douches and what often helps are otc vaginal ph balancing gels. They come in packs of single applicators and you get them most of the time in supermarkets, next to the tampons.