Types of bacterial infection
Examples of bacteria that cause infections and illness include:
- Streptococcus, a common cause of a sore throat, known as strep throat; and respiratory tract infections such as pneumonia, bronchitis, pharyngitis sinusitis and tonsillitis; also otitis medis (ear infection); scarlet fever; some serious skin infections like impetigo (superficial skin infection causing sores); the eye infection conjunctivitis. Group B Streptococcus causes meningitis.
- Staphylococcus usually causes skin infections like as furuncules (boils), abscesses, cellulitis (infected area of skin causing inflammation), impetigo (superficial skin infection causing sores); also osteomyelitis (infection of bone), pneumonia and the eye infection conjunctivitis.
- Escherichia coli (commonly known as E. coli), which normally lives in the intestines without causing harm, however, some strains cause gastroenteritis with diarrhoea and vomiting; also urinary tract infections, peritonitis and prostatitis in men.
- Chlamydia causes sexually transmitted diseases like urethritis, which is symptom free but can cause damage to female reproductive organs if not treated, such as pelvic inflammatory disease (infection and inflammation of uterus, fallopian tubes and ovaries). Chlamydia also causes eye infections like conjunctivitis and trachoma.
- Helicobacter pylori is associated with stomach ulcers.
- Haemophilus causes meningitis in babies (Haemophilus influenzae type B); also pneumonia and the eye infection conjunctivitis.
- Neisseria gonorrhoeae also known as gonococcus causes the sexually transmitted diseases gonorrhoea.
- Mycobacterium avium complex (MAC) causes opportunistic infection (bacteria that lie dormant until activated by low immunity) following HIV infection.
- Actinobacilus is one of several types of bacteria that normally live in the mouth but also cause tooth and gum diseases like a abscess and inflammation of the gum (gingivitis) or tooth (periodonitis) .
- Meningococcus causes meningitis, which is inflammation of the meninges that are the linings surrounding the brain.
- Propionibacterium acnes is a bacteria that normally lives in the sebaceous glands (oil producing glands) of the skin, but when a pore becomes blocked as happens when acne develops, the bacteria can overgrow and cause infected acne.
Types of antibiotics
Commonly used antibiotics include:
- Penicillins like Amoxycillin are broad-spectrum antibiotics that target the bacterial call wall and belong to the beta lactam group of antibiotics. They contain a structure called the beta lactam ring, which is readily attacked by the bacterial enzyme beta-lactamase and can result in resistant bacteria, such as some staphylococci. Amoxycillin is often used in combination with clavulanic acid, an antibiotic structurally related to the penicillins but is able to inactivate a wide range of beta-lactamase enzymes, which helps prevent resistance and also broadens the range of use for amoxicillin. Flucloxacillin is a narrow range penicillin-like antibiotic that is stable to the action of beta-lactamase. Phenoxymethyl penicillin is a form of penicillin that is better absorbed in the intestines and can be used when higher concentrations are needed.
- Cephalosporins like Cephalexin are broad spectrum antibiotics that target the bacterial cell wall and are a sub-group of the beta lactams but are less susceptible to destruction by beta-lactamase.
- Macrolides like Erythromycin, Clarithromycin and Azithromycin are broad spectrum antibiotics that target bacterial protein synthesis and are used to treat a variety of mild to moderate infections. They are often used for those allergic to penicillin antibiotics and to prevent opportunistic infection (bacteria that lie dormant until activated by low immunity) with Mycobacterium avium-intracellulare complex (MAC) in people with HIV. Clarithromycin is used as part of a combination therapy with an acid lowering medication like omeprazole, to treat gastric ulcers that are caused by infection of the stomach with the bacterium Helicobacter pylori.
- Lincosamides like Clindamycin target protein synthesis and are used for oral treatment of a wide range of infections. Clindamycin is also used as a topical treatment for acne that becomes infected with Propionibacterium acnes bacteria.
- Tetracyclines like Doxycycline and Minocycline target protein synthesis and are broad-spectrum antibiotics that are used primarily for respiratory tract infections like pneumonia and bronchitis; urinary tract infections; sexually transmitted diseases and for oral treatment of skin infections including infected acne.
- Trimethoprim is a synthetic antibiotic that targets an essential bacterial enzyme and is used specifically for urinary tract infections, like cystitis. It is also used in combination with other antibiotics to treat other infections when a single antibiotic has not eliminated the infection, including respiratory tract, genital tract and gastrointestinal infections.
- Sulphonamides like sulfamethoxazole block an important bacterial metabolic process. Sulfamethoxazole is used in combination with Trimethoprim, a combination known as cotrimoxazole, for infections that have not responded to a single antibiotic.
- Fluoroquinolones like ciprofloxacin and moxifloxacin target essential bacterial enzymes and are used for serious infections and those that have not responded to treatment using other antibiotics, including pneumonia, Legionnaire's disease acute sinusitis, pelvic inflammatory disease, prostatitis, peritonitis, complicated skin infections and bacteremia (bacteria in the blood circulation). They are also used for infections where antibiotic resistance causes problems with treatment.
- Nitrofurantoin is an antibiotic that damages bacterial DNA and is specifically used for urinary infections like cystitis and prostatitis.
Antibacterial and antiprotozoal medications
Metronidazole is an antibacterial and antiprotozoal medication, which means that it can be used to treat infections caused by certain bacteria and protozoan (single-cell organisms) parasites. Metronidazole works by damaging bacterial and protozoal DNA and some important enzymes. It is used to treat severe infections like septicemia, bacteremia, peritonitis, osteomyelitis, pelvic cellulitis; also teeth and gum infections. Protozoan illnesses that respond to treatment with Metronidazole include amoebiasis or dysentery caused by Entamoeba histolytica; giardiasis caused by Giardia lamblia, with symptoms including diarrhea, vomiting, and abdominal cramps; and urogenital trichomoniasis, a sexually transmitted disease of the vagina caused by Trichomonas vaginalis.
Topical use of Metronidazole as a cream or gel helps with the treatment of rosacea an inflammatory skin condition, although its mechanism of action in reducing inflammatory lesions is not known.
Topical antibiotics
Mupirocin is a topical antibiotic used for skin infections like impetigo, folliculitis (infected hair follicles) and furunculosis (boils), also for skin that becomes infected due to skin damage from eczema, psoriasis ulcers, minor burns, cuts, grazes and insect bites. It is applied as an ointment to infected areas.
Chloramphenicol and fusidic acid are used for bacterial eye infections like conjunctivitis, blepharitis (infection of the eyelid) and stye of the eye (infection at the base of the eyelash), and it is applied as eye drops.
Clindamycin is used as a topical treatment for acne that becomes infected with Propionibacterium acnes bacteria and is applied as a gel to infected areas.
Other medications
Probenecid is not an antibiotic but is used to improve the effectiveness of penicillin antibiotics by prolonging the length of time the antibiotic remains in the blood before it is excreted into the urine.