Prefixes and word elements

Meanings and examples

A-, An-

A negative, an absence of something.

e.g. anaerobic means an absence of air. See also aer-.

Ab-

Away from,

e.g. an abductor muscle is one which moves a limb or other body part away from the mid-line or another location.

Acantho-

Spine, spiny

e.g. Acanthamoeba, a species of parasitic amoebae capable of causing eye infections and fatal brain infections. The name derives from the spiky appearance of the amoebae under the microscope.

Ad-

To, towards, near

e.g. adjacent means next to.

Aer-

Air or gas

e.g. Aerobic incubation occurs in air. Microaerophilic (micro = small, aero = air, philic = loving) incubation has reduced levels of oxygen relative to normal air.  

Albo-, albus

White

e.g. the yeast Candida albicans has very white colonies. Staphylococcus epidermidis is often called Staphylococcus “albus” because it has white colonies but this is not a correct species name. See also Staphylo- and –coccus. Another term for white is leuco- or leuko-.

All-, allo-

Other, different, changed, dissimilar.

e.g. allopurinol which is drug used to treat gout. The name means “other than purine”. Allopurinol is a purine analogue; a structural isomer of hypoxanthine and is an inhibitor of the enzyme xanthine oxidase.

Ambi-

Two, both

e.g. ambidextrous means able to use either or both hands.

Amph-

Both

e.g. amphoteric means a chemical which can act as both an acid and a base.

Amyl-

Starch

e.g. amylase, an enzyme capable of breaking down starches or complex carbohydrates. Found in saliva and produced by many bacteria.

Ana-

Upwards

e.g. anabolic pathways in metabolism are those that produce complex molecules from simpler precursors and hence tend to “build up” the body. See also cata-.

Ancylo-, ankylo-

Bent.

e.g. Ancylostoma, a species of hookworm. The name literally means bent mouth (stoma = mouth or opening). Hookworms have large mouth openings and a curved or hook-shaped appearance.

Ankylosing spondylitis is a condition where the bones in the spine become fused and the term ankylosing derives from the curved or bent nature of fused bones.

Angio-

Vessel, usually in reference to blood vessels.

e.g. angiitis is an inflammation of blood vessels. See also the suffix –itis.

Ante-

Before

e.g. antenatal means before birth.

Anti-

Against

e.g. an antibiotic is a substance that is ‘against’ bacterial life, i.e. it kills bacteria. 

Apo-

Away from

e.g. apoptosis (programmed cell death) derives from falling (ptosis) away from (apo). Note that the “p” in ptosis is silent and hence apoptosis should correctly be pronounced apo-toe-sis, and not a-pop-toe-sis.

Aur-

Gold.

Staphylococcus aureus means golden Staph (with yellow or gold coloured colonies). 

Other prefixes for yellow or gold include luteo, xantho, chryseo and flavo.

See also Staphylo- and the suffix -coccus meaning berry.

Auto-

Self

e.g. autolysis is a process whereby cells digest themselves or components of themselves. Streptococcus pneumoniae autolyses quickly after 24 hours of growth on blood agar due to production of autolytic enzymes.

See also Strepto-, pneumo- and the suffix -coccus meaning berry.  

Suffixes

Meanings and examples

-aceous

Of or pertaining to, of the nature of.

e.g. dematiaceous is the name given to brown pigmented fungi, but this is something of a misnomer, as the name derives from deme = bundle, and not from the colour of the fungus.

-aemia

Pertaining to blood.

e.g. bacteraemia means bacteria in the bloodstream.

-algesia, algia

Pain.

e.g. analgesics are drugs used to treat pain. An = not, algesia = pain. Neuralgia is nerve pain.

-ase

Denotes an enzyme.

e.g. amylase is an enzymethat breaks down starches. DNAase is an enzyme that degrades DNA.

Prefixes and word elements

Meanings and examples

Bi-

Two or double

e.g. a bivalve is a shellfish having two halves such as an oyster.

Bio-

Life or living.

e.g. biology, the study of living things. (-ology means a study of.) Biochemistry is the chemistry of living things.

Brachy-

Short Pronounced bracky.

e.g. brachycephalic dogs are those breeds with short, pushed in snouts such as pugs and bulldogs. See also ceph-.

Brady

Slow

e.g. bradycardia is a slow heartbeat. Opposite to tachycardia which is a fast heartbeat.

Brev-

Short

e.g. Brevundimonas diminuta are very small bacteria.

Suffixes

Meanings and examples

-bacillus, bacilli.

A stick. Bacillus is the singular, bacilli is the plural.

e.g. bacilli are bacteria which have a rod shape, with one axis longer than the other. E.g. Actinobacillus. There is also a large genus of gram positive rod-shaped bacteria simply called Bacillus.

-blast

Germ or sprout. Generally denotes an immature, or not fully differentiated cell.

e.g. osteoblasts are immature bone cells found on the periphery of bone tissue and capable of producing new bone.

Prefixes and word elements

Meaning and examples

Cardio-

Heart

e.g. an electro-cardiogram (ECG) is a recording of the electrical activities of the heart. Myocarditis is an inflammation of heart muscle, sometimes resulting from certain viral infections. See also myo- (muscle).

Cata-

Down.

The opposite of ana-. Catabolism means the breakdown of complex materials into simpler components.

Centi-

100 or one hundredth

e.g. a centimeter is one hundredth of a metre.

Ceph-

Head

e.g. an electro-encephalogram (EEG) is a recording of the electrical activities of the brain (in the head).

Encephalitis is an inflammation of the brain, usually as a result of an infection. Should be pronounced with a hard C (like a K), hence en-kef-a-lie-tis.

Cephalosporins (Kef-al-o-spore-ins) are a class of β-lactam antibiotics originally derived from a fungus known as Cephalosporium (now Acremonium), in which spores are held in a slime enclosed mass at the head of branching hyphae (fungal filaments).

Chlor-

Green

e.g. chlorine is a green gas. See also verd- and virid-.

Chromo-

Coloured.

e.g. chromosome means a coloured (chromo) body (soma). Refers to what could be seen in a cell with early microscopes.  Chromobacterium is a genus of bacteria whose colonies are often coloured. (Contrast with Achromobacterium, which are not coloured.)

Chromogenic media are agar plates on which different bacteria produce differently coloured colonies, allowing easy identification.

Chryseo-, chryso-

Gold or yellow. (Pronounced krizio or kryso.)

e.g. the genus Chryseobacterium which are yellow pigmented bacteria.

Other prefixes for yellow or gold include luteo, xantho, aureo and flavo.

Circum-

Around.

e.g. circumference means the outside edge of a circle.

Co- or Con-

With.

e.g. co-morbidities are several diseases occurring in the same person at the same time (occurring with each other).

Conjugation is a mating of one bacterium with another.

Contra-

Against.

e.g. contra-indication is where there are factors which may result in harm if a certain treatment is prescribed - “Some medications are contra-indicated during pregnancy” because there is a risk of damage to the baby.

Corpus-

Body.

e.g. corpus callosum- the body or bundle of nerve fibres connecting the two hemispheres of the brain. Literally means tough (callosum) body because the coverings on the nerve fibres are very resilient.

Cort-, cortico-

Bark, shell or husk.

e.g. cortex is the outermost layer of many organs such as the brain and kidney.

Coryne-

Club (shaped)

e.g. the genus Corynebacterium which are bacteria with one swollen end, shaped like a club. (Pronounced core- rye-nee.)

Cryo-

Cold

e.g. cryostat, a machine for cutting frozen tissue sections. Cryoprecipitate is made from fresh frozen plasma and is rich in clotting factors, often used to treat bleeding disorders.

See also psychro-.

Crypto-

Hidden.

e.g. the yeast Cryptococcus, where the yeast cell is embedded or hidden in a thick capsule.

-Cyan-

Blue (pronounced sye-ann).

e.g. Cyanobacteria, known as blue-green algae although they are actually several genera and species of bacteria (not algae).

Poisoning with cyanide results in a characteristic blue shade to the lips.

The pigment pyocyanin makes colonies of Pseudomonas aeruginosa blue/green in colour (along with another pigment pyoverdin, which is green).

See also glauco-.

Cyto-

A cell or pertaining to a cell

e.g. cytoplasm, the internal material (protoplasm or cytosol) within a cell. Derives from the Greek word for a vessel.

Suffixes

Meaning and examples

-chrome

Colour.

e.g. fluorochromes are compounds used to label reagents in techniques such enzyme linked immunosorbant assays (ELISAs). They fluoresce different colours under UV light. See also the prefix – fluoro-.

-cidal

Killing.

e.g. bactericidal antibiotics kill bacteria outright and this often results in release of materials such as LPS which can cause further problems as they may be pro-inflammatory.

-coccus, cocci

A berry. Coccus is the singular form, plural is cocci.

e.g. Cocci are bacteria that have a spherical shape, like a small berry. E.g. Enterococcus.

-coele

A swelling or tumour. Pronounced seal. Can also mean a cavity or empty chamber.

e.g. a haemocoele is a swelling filled with blood.

-cyst

Sac, pouch or bladder.

e.g. protozoan parasites produce enclosed “cysts”, covered by a protective coating, in order to move from host to host. As the pass through the intestine, the parasite excysts i.e. exit the cyst to form the free living form of the organism, called a trophozoite. The worm that causes hydatid disease produces berry like cysts in host tissue where the parasites are enclosed in thick-walled sac-like structures.

Can also be used as a prefix and word element e.g. cystitis is a urinary tract infection, confined to the urinary bladder. Cholecystitis is inflammation of the gall bladder.

-cyte

A cell or hollow vessel. Generally denotes a mature form a cell.

e.g. erythrocytes are fully differentiated red blood cells.

Prefixes and word elements

Meaning and examples.

De-

Down, reduce or remove.

e.g. de-escalate means to go down or decrease. Demyelination means loss of myelin from nerve fibres, occurs in multiple sclerosis.

Deca-

10

e.g. a decade is 10 years long.

Deci-

One tenth

e.g. a decilitre is one tenth of a litre or 100 millilitres. An older value for volume used in clinical chemistry.

Demi-

Half. See also hemi and semi. 

Di-, diplo-

Two, double

e.g. divalent means two charges such as for Ca⁺⁺ - a divalent cation. Diplococcus is a common name for coccoid bacteria found in pairs. See also the suffix -coccus meaning berry.

Dia-

Through

e.g. dialysis means movement of solutes through a semi-permeable membrane.

Diarrhoea results in rapid movement and expulsion of intestinal contents through and from the GIT.

Dis-

Apart or removed

e.g. dis-assembled

Dys-

Bad, difficult or not functional

e.g. dysuria means pain on urination, often accompanying a urinary tract infection.

Prefixes and word elements

Meaning and examples

E-, ex-, exo-

Out of or deriving from.

e.g. exogenous infections are derived from organisms entering from outside the body. Contrast with endogenous (from within).

Echino-

Spiny or prickly

e.g. Echinococcus is a species of tapeworm that causes hydatids. Literally means spiny berries – the parasite forms berry-like cysts full of tapeworm parts including the spiny hooklets by which it attaches to the host. See also the suffix -coccus meaning berry.

Ecto-

Outside

e.g. ectoplasm is the clear, mucoid outer layer of the cytoplasm in amoeboid cells. Contrast with endoplasm.

En-

In

e.g. engulf means to take in (as in phagocytosis).

Endo-

Within

e.g. endogenous infections result from organisms already within the body. Contrast with exogenous (from outside).

Entero-

Intestine or gut.

e.g. enteritis is an inflammation of the gut, commonly caused by enteric bacteria. Refers to the intestines but not the stomach. See gastro- to refer to the stomach. 

Epi-

On or upon.

e.g. the epidermis is the topmost layer of tissue in the skin, found on or upon the dermis (skin).  

Erythro-

Red.

e.g. erythrocytes are red blood cells.

Other terms for red include rubro-, rubri-, roseo and rhodo.

Extra-

Outside of.

e.g. extracellular means outside of a cell, external. Contrast with intracellular (inside a cell).

Exo-

Outside of or outward

e.g. the exoskeleton of an insect is its outside covering. Similar to ecto-

Eu-

True

e.g. eukaryotes are cells with a true nucleus enclosed in a nuclear membrane.

Suffixes

Meaning and examples.

-elle

Small.

e.g. organelles are the small internal structures within cells.

-escent

Becoming, developing a state.

e.g. coalescent means objects joining together e.g. colonies on an agar plate may become coalescent or grow into each other if incubated for too long.

-ectomy

To cut out.

e.g. an appendectomy is an operation to remove an appendix.

Prefixes and word elements

Meaning and examples

Flavo-

Yellow

e.g. a type of flavivirus causes yellow fever. Other prefixes for yellow or gold include luteo, xantho, aureo and chryseo.

Fluoro-, flu-

A flowing. Derives from the use of the mineral fluorspar as a metallurgical flux in smelting. Now refers to either the halide, fluorine, or to materials which give off light (glow) under UV illumination.

e.g. fluorescence microscopy utilizes UV light to illuminate the object. Note that the technique is fluorescence, the object (and not the microscope) is fluorescent.

Flucloxacillin is a penicillin type antibiotic which has fluorine and chlorine molecules attached.

Suffixes

Meaning and examples

-form, -forme

Shape.

e.g. Neisseria bacilliformis, a species of Neisseria found in the oral cavity and which is an opportunistic pathogen. Neisseria are usually cocci, but this species has the “form” of a bacillus.

Prefixes and word elements

Meaning and examples

Gastro-

Stomach or belly.

e.g. gastro-enterology is the study of the gut, including both the stomach and intestines. See also the suffix -ology, a study of.

Geo-

Land or earth.

e.g. certain geophilic fungi cause human tinea. These fungi are found in soil. See also the suffix -philus (loving).

Glauco-

Blue/grey (pronounced glor-ko).

e.g. glaucous leaves are found on many Australian native plants such as blue gums.

Gloss-

Tongue.

e.g. glossitis is an inflammation of the tongue. See also the suffix –itis.

Suffixes

Meaning and examples

-gen, -genes, -genic

Producing, giving rise to, generating.

e.g. a pathogen is any organism that causes damage to a host and results in pathological change.

Methanogenic bacteria in the gut produce methane.

Streptococcus pyogenes produces pus (pyo = pus).

-gnosis

Knowledge, to know.

e.g. diagnosis – to know the cause of a disease through (dia) or via analysis of symptoms and other characteristics.

Prefixes and word elements

Meaning and examples

Haemo-

Blood. (American spelling = hemo.)

e.g. haemoglobin is the oxygen carrying pigment found in red blood cells. Haemophilus is a genus of bacteria requiring components of blood for growth. Literally means blood loving. See also the suffix – philus (loving).

Halo-

Salt (i.e. NaCl).

e.g. Staphylococcus is a halophile meaning it can grow in media with a high salt content. See also the suffix – philus (loving).

Hemi-

Half

e.g. hemisphere is half a sphere.

See also demi- and semi-.

Hetero-

Different, other.

See also allo-.

e.g. heterophile antibody, which is an antibody with affinity for something other than, or as well as, the antigen that stimulated its production. Used to detect glandular fever. See also the suffix – philus (loving).

Holo-

Entire or whole

e.g. holistic medicine aims to treat the entire patient, not just the symptoms.

Homo- (1)

Man

Humans belong to the species Homo sapiens – “thinking men”. Hominids are early forms of men. Man and men are used in the generic sense here to include both males and females.

Homo- (2)

Same

e.g. homogeneous means a suspension with the same consistency throughout.

Hydro-, hygro-

Water, wet.

e.g. Aeromonas hydrophila, an aquatic organism. See also –philus (loving).

Hygroscopic powders readily absorb water. Many dehydrated (water removed) media are hygroscopic and must be kept dry for optimal use.

Hyper-

Over or above. Higher than.

e.g. hypertension is high blood pressure.

Hypo-

Under or below. Less than.

e.g. hypotonic solutions have a concentration less than that of the inside of cells.

Prefixes and word elements

Meaning and examples

In-, im-

To, toward or into.

e.g. innate means in-built or born with/born into (nate refers to birth). Innate antibiotic resistance in bacteria is a characteristic feature of the organism that they have always displayed. Contrast with acquired resistance which the bacteria develop via mutation and/or acquisition of mobile genetic elements.

Infra-

Below or beneath.

e.g. infra-red radiation is those wavelengths in the electro-magnetic spectrum below those of red visible light, although the wavelength is actually longer. The EMS is usually viewed from the longer wavelengths to the shorter. See also ultra-.

Inter-

Between.

e.g. connective tissue is found in the intercellular regions between cells.

Intra-

Within

e.g. intracellular organelles in eukaryotic cells include mitochondria and lysosomes. Compare with extra-.

Iso-

Same, equal.

e.g. an isotonic solution has approximately the same concentration of solutes as normal cytoplasm. Cells placed in isotonic media should not lyse or shrink.

Suffixes

Meaning and examples

-itis

An inflammation.

e.g. hepatitis is inflammation of the liver and may be caused by many factors including viruses and excess alcohol usage.

Prefixes and word elements

Meaning and examples

-Kary-

Kernel (inner part of a nut or seed). Refers to the nucleus.

e.g. bacteria are classified as prokaryotes – they do not have a true nucleus. Pro- refers to before i.e. bacteria are “before nuclei”. (Not pro in the sense of “in favour of”.) They evolved earlier than nucleated cells. See also pro- and eu-.

Prefixes and word elements

Meaning and examples

Leuco-, leuko-

White.

e.g. leukocytes are white blood cells.

Other terms for white include albus, alba

Luteo-

Yellow.

e.g. Micrococcus luteus, which produces tiny (see micro-) bright yellow colonies on blood agar.

Other prefixes for yellow or gold include flavo-, xantho, aureo and chryseo.

Suffixes

Meaning and examples

-lyse, -lytic

To break open a cell, to dissolve cell membranes.

e.g. haemolytic bacteria can lyse red blood cells.

Prefixes and word elements

Meaning and examples

Macro-

Large.

e.g. a macrophage is a type of phagocytic cells found in tissue. A large amoeboid cell. See also phago-.

Mela-, melanino-

Brown/black.

e.g. Prevotella melaninogenicus is a species of dark pigmented anaerobic gram negative bacteria.

Meso-

Middle, intermediate, halfway.

e.g. mesothelium is the layer of epithelium lining internal cavities such as the peritoneum. It derives from mesoderm, the middle layer in a developing embryo. See also peri-.

Meta-

After or behind, higher or beyond.

e.g. meta-analysis occurs after a study or studies have been carried out and higher level analyses of the results are integrated.

Metabol-

Changeable, changing, a transition.

e.g. metabolism, the chemical reactions that occur within the body.

Micro-

Small. One millionth (10^-6).

e.g. microbiology – the study of small things.

Microlitre = One millionth (10^-6) of a litre.

Milli-

One thousandth (10^-3).

e.g. a millimetre is 10^-3 of a metre.  

Mis-

Wrong or bad.

e.g. a missense mutation results in substitution of a different amino acid in the final protein product. The sequence of the original gene was copied wrongly when the DNA in the chromosome was reproduced, and it results in the wrong amino acid in the protein.

Mito-

Thread.

e.g. mitosis where the chromosome condense and appear thread-like under the microscope.

Mitosporic fungi are those fungi for which a sexual reproductive state is not known. They reproduce by production of asexual spores (by mitosis) from the vegetative hyphae (or threads).

Mono-

One.

e.g. monocytes, a type of white blood cell which has a single, large, bean-shaped nucleus. Precursors to macrophages. Mononuclear white blood cells include both monocytes and lymphocytes, both having single entire nuclei as opposed to granulocytes which have segmented nuclei.

Infectious mononucleosis (glandular fever), is an infection caused by Epstein-Barr virus which results in increases and abnormal changes in mononuclear white blood cells.

-Morph-

Shape.

e.g. polymorphonuclear cells have nuclei with variable numbers of segments hence the literal meaning of “many shaped nucleus”. Commonly used in clinical microbiology to indicate the presence of inflammatory cells (usually neutrophils) in a specimen which implies an infection is occurring. Abbreviated to “polys”. See also poly-.

Multi-

Many.

e.g. erythema multiforme, a skin rash with multiple presentations but usually characterized by raised red lesions on various parts of the body. Associated with Herpes Simplex infections, various bacterial infections, and with use of some antibiotics, particularly the sulfonamides. This can give rise to the severe form of erythema multiforme known as Stevens-Johnson syndrome. See also erythro- and -forme. Another term for many is poly-.

-Myco-

Relating to fungi.

e.g. Mycobacterium tuberculosis, the causative agent of human TB. These are acid fast bacteria unlike typical gram positive or negative forms, and with a thick waxy cell wall. Originally thought to be fungi.

See also the suffixes – myces and -mycin.

Myo-

Muscle.

Relates to all types of muscle – skeletal, cardiac and smooth.

e.g. myoglobin, the oxygen carrying molecule similar to haemoglobin found in muscle cells.

-Myxo-

Slime or mucus.

e.g. orthomyxo- and paramyxo- viruses cause respiratory infections and production of mucus.

Myxomatosis is a usually fatal viral disease of rabbits which results in swelling of mucous membranes and formation of skin tumours. See also –oma.

Suffixes

Meaning and examples

-meter, - metry

To measure.

e.g. micrometry is the measurement of small things in a microscope. A thermometer measures heat.

-monas

A unit, solitary. This is a common ending on bacterial names denoting individual cells (not in clusters, pairs or chains) and usually rod-shaped or bacilli.

e.g. Chryseomonas, a genus of yellow pigmented bacilli-shaped bacteria.

-mycin

Any naturally produced antibiotic derived from a fungal or Actinomycete source. From myces = fungus.

e.g. streptomycin – the first antibiotic of the aminoglycoside class isolated from Streptomyces.

Note that while gentamicin is also an antibiotic of the aminoglycoside class, it is synthetic, hence is not spelt gentamycin with a “y”.

Prefixes and word elements

Meaning and examples

Neo-

New.

e.g. neomycin, one of the earliest isolated antibiotics of the aminoglycoside group, was named neomycin because it was originally proposed as a new treatment for streptomycin resistant bacteria including Mycobacterium tuberculosis. See also –mycin.

-Nephro-

Relating to the kidney.

e.g. glomerulo-nephritis is an infection/inflammation of the tubules of the kidney. A complication of some urinary tract infections and a possible consequence of deposition of antigen/antibody complexes on the glomerular basement membrane following a streptococcal infection of the throat.

Neuro-

Relating to nerves, but original meaning is sinew, tendon or cord. Relates to the appearance of nerve fibres which are covered in tough connective tissue similar to tendons.

e.g. the food spoilage fungus, Neurospora crassa, used extensively in genetic research, which has striated spores said to resemble axons (nerve fibres).

Prefixes and word elements

Meaning and examples

Ob-

Against or facing as in obstructing.

e.g. obstetrics, the medical specialization dealing with pregnancy and birth. The term derives from obstetricus or pertaining to a midwife. Obstetrix is the Latin term for a midwife, and literally means one who stands opposite (to a woman giving birth.)

Oligo-

Few (a few or not many).

e.g. oligomers are short lengths of DNA (a few bases long) used as primers in the polymerase chain reaction (PCR).

The outer membranes of gram negatives are composed of material called lipo-polysaccharide LPS). In some bacteria there are fewer saccharide residues, resulting in shorter chains. The material is then called lipo-oligosaccharide (LOS).

Onco-

Mass, swelling, tumour. Relates to cancer.

e.g. oncogenic viruses cause cancer, an example of which is human papilloma virus, associated with cervical cancer. See also –genic.

Proto-oncogenes are genes, which when mutated in certain ways, can give rise to or promote the development of cancers. See also pro-, proto- and -genic.

Oo-

Egg.

Oo should be pronounced sounding both o’s i.e. o, pause, o, and not an oo sound as in too.

e.g. oocysts are structures produced by certain parasites, which contain the eggs of the organisms and protect them from the environment.

Ornitho-

Relating to birds.

e.g. ornithosis is a respiratory infection caused by Chlamydia psittaci, carried by birds of the parrot family.

Ortho-

Straight, upright, true, proper, regular, correct.

e.g. orthomyxoviruses include the viruses which cause influenza, a respiratory infection resulting in production of mucus (-myxo-). Of all the RNA viruses causing respiratory infections, the orthomyxoviruses are the only ones to cause “true” influenza. They display straight or upright protein spikes on the surface of the viral particles. See also –myxo- and para-.

Osteo-

Relating to bone.

e.g. osteomyelitis is an infection in bone and bone marrow.

Suffixes

Meaning and examples

-oid

Of the form of…

e.g. ovoid cells are roughly oval in shape.

-ology

Study of.

e.g. microbiology is the study of small (micro), living (bio) things.

-oma

A swelling or tumour.

e.g. a haematoma is a bruise or swelling caused by bleeding into the tissues.

-osis

A condition or process, a disease.

e.g. a mycosis is a fungal infection. This is the singular form, the plural is mycoses, pronounced my-co-sees.

Prefixes and word elements

Meaning and examples

Para-

Beside, near, close.

e.g. paramyxoviruses are very similar to orthomyxoviruses in structure and the ability to cause respiratory infections, but they are not exactly the same, hence they are close to but not the same as orthomyxoviruses.

Parvo-

Small.

e.g. parvovirus, the causative agent of several human and animal diseases including “slapped cheek syndrome” and infections in dogs. The viruses are very small – 25nm in diameter.

Per-

Through or thoroughly, utterly, very.

e.g. the causative organism of gas gangrene is a bacterium called Clostridium perfringens. Gangrene results in disintegration/liquefaction of tissue and the name perfringens derives from per = thoroughly and frango = to shatter or break apart. Clostridium derives from kloster = a spindle, because the bacteria are bacilli shaped, with some species having spores in the centre of the cell causing a swelling which gives rise to the spindle shape.

The disease pertussis or whooping cough, which can result in severe paroxysmal coughing, where sufferers are unable to stop coughing until they vomit and where they draw breath with difficulty through inflamed airways, resulting in the characteristic “whooping” sound. Can result in oxygen deprivation and brain damage, especially in young babies, hence utterly debilitating. See also -tussis.

There is also a chemical use of per – where atoms may be in their highest oxidation state or the molecule may have the most of a particular atom that is possible e.g. hydrogen peroxide.

Peri-

Around or enclosing.

e.g. pericardium is a membrane surrounding the heart. See also cardio-.

-phage-

To eat.

e.g. phagocytic cells “eat” or ingest foreign materials including micro-organisms. Macrophage literally means big eater.

Viruses of bacteria are called bacteriophages because they can lyse (“eat”) bacteria.

Pheno-

To show or shine.

e.g. phenotype is the sum of the expressed genes of an organism. The appearance of an organism. Depends on which genes are expressed and represents the proteins produced. Compare with genotype which is the sum of all genes within an organism, whether they are expressed or not.

Phyto-

Relating to plants. “That which has grown.”

e.g. phytochemicals, or compounds derived from plants, are increasingly being explored as sources of new antimicrobials.

Poly-

Many.

e.g. polysaccharides consist of many sugar residues joined together.

Post-

After or behind.

e.g. post-infection complications of Streptococcal infections can include rheumatic heart disease and glomerulonephritis.

Pneumo-

Air or lung.

e.g. Streptococcus pneumoniae, a common causative agent of the lung infections and inflammation known as pneumonia. The infection must involve the lower lung and alveoli to be a true pneumonia. See also Strepto- and -coccus.

Other causes of pneumonia include Chlamydia pneumoniae and Klebsiella pneumoniae.

Pre-

Before.

e.g. prebiotics, which are non-digestible components of foods that provide nutrients to certain beneficial bacteria in the gut, stimulating their growth over other, possibly pathogenic, bacteria. Prebiotics are mostly forms of carbohydrate such as inulin and galacto/fructo-oligosaccharides.

Pro- (1)

For, In favour of.

e.g. probiotics – literally “in favour of life”. Generally beneficial bacteria given to replenish normal flora in the gut. Compare with antibiotic (against life).

Pro- (2), proto

Before, in front of, preceding, first.

e.g. bacteria are prokaryotes (see under – karyo-).

Proto-oncogenes (see under onco-) can give rise to cancers when mutated – they precede the cancerous form.

Protozoa are single-celled eukaryotic organisms and include several species of human parasites. Believed to be some of the earliest evolved life forms exhibiting animal like behavior such as movement. The name literally means “first animals”. See also -zoa.

Pseudo-

False or spurious.

e.g. the bacterial genus Pseudomonas. It is believed this genus was so-named because of a resemblance to the nanoflagellate Monas, which is a protist (protozoan), not a bacterium, hence “false” Monas.  See also-monas.

Psychro-

Cold.

e.g. psychrophilic bacteria grow preferentially in cold temperatures (ranging from minus 15°C to plus 10°C), much less than the body temperature preferred by most pathogens. See also -phil-.

Another term for cold is cryo-.

Pyo-

Pus i.e. an inflammatory exudate containing dead cells, dead bacteria and debris from lysed cells and bacteria. Indicative of an infection.

e.g. Streptococcus pyogenes, or group A Streptococci, so called because skin infections with this organism elicit the production of pus. See also -genic = producing, Strepto- and -coccus.

Pyro-

Heat or fire.

e.g. the lipopolysaccharide found in gram negative bacteria is also known as pyrogen because it is capable of inducing fever. See also -genic.

Suffixes

Meaning and examples

-path, -pathy

Relating to disease/pathology. From pathos meaning suffering.

e.g. nephropathy is a disease of the kidneys.

-parous, partum

Birth, to give birth to.

e.g. a animal which gives birth to one offspring at a time is monoparous.

-phyte

A plant or pathological growth.

e.g. an osteophyte is an abnormal growth of bone.

Epidermophyton is a genus of dermatophyte fungi which grow on skin and cause tinea.

-phile, -phil

Loving.

e.g. extremophile bacteria grow at either very high or very low temperatures or in extremes of pH.

Staphylococcus is a halophile – it can grow in media with a high salt content.

-phobe

Hating, fearing, avoiding.

e.g. hydrophobic materials shun or avoid water, they are not miscible with water. See also hydro-.

-phore

To bear or carry, the bearer.

e.g. electrophoresis is the technique whereby segments of DNA or RNA, or protein are “carried” through a gel by the flow of electrical current.

-plasm

To shape, mould or create.

e.g. cytoplasm is the living material inside a cell, it “creates” the cell.

-pnea

Breathing.

e.g. dyspnea or difficulty breathing, a common feature of pneumonia.

Prefixes and word elements

Meaning and examples

Re-

Again, back

e.g. sometimes agar plates have to be re-incubated (incubated again) if the bacterial colonies have not grown sufficiently.

Retro-

Backwards.

e.g. retroviruses such as human immunodeficiency virus (HIV) have an enzyme, reverse transcriptase, which is capable of copying RNA back into DNA. This is backwards according to the original paradigm which stated that the flow of information in a cell was always DNA → RNA → protein.

Rhino-

Nose.

e.g. rhinitis is an inflammation of the nose, occurs with the common cold.

Rhizo-

Root (as of a plant).

e.g. growth of organisms is said to be rhizoid if the colony spreads out in a branching, feather-like pattern similar to the roots of a plant.

Rhodo-

Rose pink or red.

e.g. Rhodococcus equi, which produces salmon pink colonies on blood agar.

Other terms for red include erythro-, roseo and rubro-.

Roseo-

Red or pink.

e.g. roseola, a viral infection of babies and children that results in a pink/red rash.

-Rubro-, -rubri-

Red

E.g. pyorubrin, a reddish pigment produced by Pseudomonas aeruginosa. Other prefixes for red include eythro-, roseo- and rhodo-.

Suffixes

Meaning and examples

-rrhage

To burst forth.

e.g. haemorrhage means bleeding, the blood is bursting forth from the blood vessels.

-rrhoea

Flow.

e.g. diarrhoea, which literally means to flow through. Dysmenorrhoea is an abnormality in the menstrual flow.

Prefixes and word elements

Meaning and examples

Sapro-

Rotten or putrid.

e.g. fungi are saprophytes, feeding off of and growing on dead or decaying matter.

Schis-, schiz-

Split or divide.

e.g. Schistosoma, a genus of parasitic worms causing schistosomiasis or bilharzia. So-called because of a structure found on the adult males – a groove into which the female fits during mating. See also -soma.

Semi-

Half.

e.g. semi-solid agar is used to test for bacterial motility because it contains less than the normal amount of agar as the setting agent and hence is “half” or partially set only.

See also hemi- and demi-.

Staphylo-

Bunch of grapes.

e.g. Staphylococcus. The name derives from the appearance of the bacteria in a gram stain where they form into clusters of purple-staining spherical cells resembling bunches of grapes. See also -coccus.

Strepto-

Twisted or turned.

e.g. Streptococcus. These bacteria display pairs of cocci joined end to end to produce curved or “twisted” chains. See also -coccus.

Sub-

Under, below.

e.g. a subacute infection does not produce symptoms, it is “under” the normal level of severity.

Suboptimal concentrations of antibiotics (less than therapeutic levels) can induce development of resistance.

Super-, Supra-

Above.

When whole, uncoagulated blood is centrifuged, the supernatant (liquid phase above the cells) is the plasma.

Suffixes

Meaning and examples

-scope, scopy

To look or see. The act of looking.

e.g. a microscope is an instrument for looking at very small objects. An endoscope is an instrument for “looking within”, used for endoscopy or examination of the large bowel for colon cancer.

-some

Body. (pronounced sohme with a long o, and not sum, as in a few).

e.g. Endosomes are organelles within cells involved in killing of any foreign organisms that have been phagocytosed.

-sperm

Seed.

e.g. an angiosperm is a vascular plant that produces seeds.

-spore

Seed.

e.g. the genera Bacillus and Clostridium produce endospores within the bacterial cells.

-static

Stopping, halting.

e.g. bacteriostatic antibiotics suspend growth of bacteria but do not necessarily kill them outright. If re-incubated in the absence of the antibiotic, the bacteria can recover and grow.

Prefixes and word elements

Meaning and examples

Tachy-

Fast

e.g. tachycardia is a very fast heartbeat.

Telo-

End.

e.g. telomeres are the structures at the end of chromosomes in eukaryotic organisms, which allow the replication of the chromosome without loss of genetic material.

Thermo-

Heat

e.g. the bacterium, Bacillus stearothermophilus is able to withstand very high temperatures and grows at higher than 37^oC. It is commonly used to test whether autoclaves are operating correctly. See also –phil.

Trich-

Hair.

e.g. Trichophyton rubrum, a species of dermatophilic fungi which infects skin and causes tinea and ringworm. See also phyto-. The name literally means hairy plant and describes the appearance of many filamentous fungi. See also rubra-.

Suffixes

Meaning and examples

-troph

One who nourishes.

e.g. many bacteria are chemoorganotrophs – they obtain energy from the oxidation of reduced organic compounds. They can do this via respiration, where oxygen is the terminal electron acceptor in the electron transport chain, or via fermentation anaerobically, where organic nutrients, usually sugars, are metabolized to produce ATP and short chain fatty acids (acetic, lactic) are produced as a byproduct.

 -tussis

 Coughing.

e.g. pertussis or whooping cough. Anti-tussives are medications to reduce coughing. 

Prefixes and word elements

Meaning and examples

Ultra-

Beyond.

e.g. ultra-violet light (UV) is at a wavelength beyond the wavelength of visible violet light. The wavelength is actually shorter and more energetic.

Suffixes

Meaning and examples

-uria

Pertaining to urine.

e.g. bacteriuria means bacteria in the urine, possibly indicating a urinary tract infection.

-uris

Tail.

e.g. the worm Trichuris trichura has a long “whip” like tail.

Note that caud- also means tail.

Prefixes and word elements

Meaning and examples

-Verd-

Green.

e.g. the pigment pyoverdin produced by Pseudomonas aeruginosa is green.

-virid-

Green.

e.g. the non-pathogenic alpha haemolytic Streptococci are sometimes called Streptococcus viridans because alpha haemolysis causes greening of blood agar.

Prefixes and word elements

Meaning and examples

Xanth-

Yellow.

e.g. after a bleed into the sub-arachnoid space in the meninges, the CSF is often described as being xanthochromic due to old haemoglobin and its breakdown products which stain the fluid yellow.

Xanthomonas is a genus of yellow pigmented bacteria, many of which are pathogens of plants.

Other prefixes for yellow or gold include flavo-, luteo-, aureo- and chryseo-.

Xeno-

Alien, foreign.

e.g. a xenobiotic is any substance not produced in the body.

Xero-

Dry.

e.g. xeroderma, skin diseases characterized by dry, scaly skin.

Prefixes and word elements

Meaning and examples

Zoo-

Animal. Pronounced by sounding both o’s as in zo-o.

e.g. a zoonosis is an infectious disease transmitted from an animal to humans.

also the suffix -zoa, referring to animals.