Abbreviations, Acronyms, and Initialisms

An abbreviation is a truncated word; an acronym is made up of parts of the phrase it stands for and is pronounced as a word (ELISA, AIDS, GABA); an initialism is an acronym that is pronounced as individual letters (DNA, RT-PCR). For the purposes of this section, "abbreviation" will refer to all of these.

Avoid excessive abbreviations. Use standard abbreviations only; do not make up abbreviations. Spell out on first mention and use only if it occurs a substantial number of times (subject to editorial discretion).

Use STI for sexually transmitted infection but not for soft tissue infection (SSTI okay for skin and soft tissue infection).

Avoid SOB (shortness of breath, sulfur-oxidizing bacteria), if possible.

Use WUPyV and KIPyV for WU and KI polyoma viruses.

In text, use “number” when followed by a word, “no.” when followed by a numeral.

We assigned Genbank accession numbers.
We submitted it under GenBank accession no. ABC123. 

Do not introduce an abbreviation in a heading.  Abbreviations can, however, be used in a heading if previously established.

Abbreviations should be written out in Affiliations and Acknowledgments (unless abbreviated in text). Affiliations may be abbreviated at the author's discretion in the Address for Correspondence.

When writing out affiliations, use the official spelling, which may or may not be American spelling. Words to look for are Programme vs. Program, Centre vs. Center, Organisation vs. Organization.

WHO, World Health Organization
OIE, World Organisation for Animal Health

SI units used with a numeral are never spelled out. The following are used without spelling out on first mention (list not comprehensive).

AM, PM (time; caps, no periods)
AMP, ADP, ATP
AIDS
BCG (but at first mention specify Mycobacterium bovis BCG)
BLAST
bp, kb, kbp (when used with a numeral, but spell out when not used with a numeral)
CFU
CI
CSIRO
DDBJ (DNA Data Bank of Japan)
DDT
DNA, RNA, cDNA, mRNA, tRNA, or rDNA (Note: c, complimentary; m, messenger; t, transfer; r, ribosomal)
dNTPs (deoxynucleotide triphosphates)
ELISA
EDTA
EMBL (European Molecular Biology Nucleotide Sequence Database)
HEPA filter
HEPES buffer
IU, U
M, F (in tables and figures only; write out male and female in text)
MDCK
MIC, MIC₅₀
N (concentration)
PCR
Pers. comm.
PFU
ppb, ppm, ppt
rpm
SD, SE, SEM
sp., spp., sp. nov (with organism name), subsp. (preferred over ssp.)
Tris
unpub. data
UV
vol/vol, wt/vol, wt/wt

In instances when an abbreviation has become the de facto name, spelling out may cause confusion, particularly if the term appears only once. In these instances, write the abbreviation, then spell out in parentheses, even if it appears only once in the article. On subsequent occurrences, use the abbreviation.

VDRL (Venereal Disease Research Laboratory) test

The article "a" or "an" should match the sound of the abbreviation or acronym, not the word for which it stands.

an HMO report, a MRSA infection (usually pronounced Mersa), a NICU (usually pronounced nick-you]

However, articles are often omitted in front of abbreviations.

CDC, not the CDC

Abbreviate the following in tables, figures, and in the Methods section of research articles. Exception: Write out in research articles if not preceded by number or if used alone; i.e., not part of a "recipe."

days	d
weeks	wk
months	mo
seconds	s
minutes	min
years	y

If CLSI is used in a reference name, then "formerly NCCLS" is not needed. But if the reference has only NCCLS, then add "CLSI (formerly NCCLS)."

Abbreviate Street when part of address, with no period.

 265 Peachtree St, Atlanta, GA

Abbreviate Saint, with period.

St. Louis encephalitis

Abbreviate UK and USA when used as part of an address, e.g., affiliations and address for correspondence.

Define ICD code revisions as follows:

International Classification of Diseases, 10th revision (ICD-10)

Use a capital H for human virus abbreviations, unless otherwise directed by author or precedent, e.g., HMPV, not hMPV.

(back to top)