Bma Illustrated Medical Dictionary

Aerobic bacteria require oxygen to grow

and multiply; in the body, these are

most commonly found on the skin or in

the respiratory system. Anaerobic bac-

teria thrive where there is no oxygen,

deep within tissue or wounds. They

reproduce by simple division, which can

take place every 20 minutes. Some bacte-

ria also produce spores that can survive

high temperatures, dry conditions, and

lack of nourishment; and some produce

poisons (either endotoxins or exotox-

ins) that are harmful to human cells.

The body’s immune system attacks

invading bacteria, but in some cases

treatment with antibiotic drugs is neces-

sary and will speed recovery. Superficial

inflammation and infected wounds may

be treated with antiseptics. Immunity to

invading bacterial diseases, such as

some types of meningitis, can be ac-

quired by active immunization. (See also

infectious disease.)

bacterial vaginosisAn infection of the

vaginathat causes a greyish-white dis-

charge and itching. The disorder is due

to excessive growth of bacteria that

normallylive in the vagina. It is more

common in sexually active women and

is treated with antibiotic drugs.

bactericidalA term used to describe

any substance that kills bacteria. (See

also antibacterial drugs; antibiotic drugs.)

bacteriologyThe study of bacteria, par-

ticularly of the types that cause disease.

Bacteriology includes techniques used

to isolate and identify bacteria from

specimens such as a throat swab or

urine. Bacteria are identified by their ap-

pearance under a microscope, including

their response to stains (see staining)

and the use of culture. Testing for sensi-

tivity to antibiotics may be performed.

bacteriostaticA term used to describe

a substance that stops the growth or

multiplication of bacteriabut does not

kill them. (See also antibacterial drugs;

antibiotic drugs.)

bacteriuriaThe presence of bacteriain

the urine that is abnormal.

bad breathSee halitosis.

bagassosisA rare disease affecting the

lungs of workers who handle mouldy

bagasse (the fibrous residue of sugar-

cane after juice extraction). Bagassosis

is one cause of allergic alveolitis. Symp-

toms develop 4–5 hours after inhaling

dust and include shortness of breath,

wheezing, fever, headache, and cough.

Repeated dust exposure may lead to

permanent lung damage.

Baker’s cystA fluid-filled lump behind

the knee. A Baker’s cyst is caused by

increased pressure in the knee joint due

to a buildup of fluid in a disorder such

as rheumatoid arthritis. Most Baker’s

cysts are painless, and some disappear

spontaneously. Occasionally, a cyst may

rupture, producing pain and swelling in

the calf that can mimic a deep vein

thrombosis (see thrombosis,deep vein).

Diagnosis of a Baker’s cyst is confirmed

by ultrasound scanning. Treatment is

rarely needed.

balanceThe ability to remain upright and

move without falling over. Information on

body position is relayed to the brain by

many parts of the body: the eyes; pro-

prioceptors (sense organs) in the skin,

muscle, and joints; and the labyrinth of

the inner ear. The cerebellum(part of the

brain) integrates the information and

sends instructions to enable various

parts of the body to perform adjust-

ments needed to maintain balance.

Disorders affecting the ear, brain, or

spinal cord commonly affect balance.

Ear disorders include labyrinthitisand

Ménière’s disease. Less commonly, otitis

mediamay affect balance.

BACTERIAL VAGINOSIS BALANCE

Flagellum

BACTERIA

Nucleoid containing

genetic material

Cell wall

B

A ROD-SHAPED BACTERIUM

Pilus