Microbiology, 2021

1194 E • Glossary
sequence
integrase inhibitors antiviral drugs that
block the activity of the HIV integrase
responsible for recombination of a DNA
copy of the viral genome into the host cell
chromosome
intercalating agent molecule that slides
between the stacked nitrogenous bases of
the DNA double helix, potentially resulting
in a frameshift mutation
interference distortion of a light wave due
to interaction with another wave
interferons cytokines released by cells
that have been infected with a virus;
stimulate antiviral responses in nearby
cells as well as the cells secreting the
interferons
interleukins cytokines largely produced
by immune system cells that help
coordinate efforts against invading
pathogens
intermediate filament one of a diverse
group of cytoskeletal fibers that act as
cables within the cell and anchor the
nucleus, comprise the nuclear lamina, or
contribute to the formation of
desmosomes
intermediate host a host in which a
parasite goes through some stages of its
life cycle before migrating to the definitive
host
intermittent common source spread a
mode of disease transmission in which
every infection originates from the same
source and that source produces
infections for a period before stopping and
then starting again
interphaseperiod of the cell cycle leading
up to mitosis; includes G1, S, and G2
phases (the interim period between two
consecutive cell divisions
intertrigo a rash that occurs in a skin fold
intestinal fluke a trematode worm that
infects the intestine, often caused by
Fasciolopsis buski
intracellular targeting toxin see A-B
exotoxin
intrinsic growth rate genetically
determined generation time under
specific conditions for a bacterial strain
intron intervening sequence of a
eukaryotic gene that does not code for
protein and whose corresponding RNA
sequences are removed from the primary
transcript during splicing
intubation placement of a tube into the
trachea, generally to open the airway or to
administer drugs or oxygen
in-use test a technique for monitoring the
correct use of disinfectants in a clinical
setting; involves placing used, diluted
disinfectant onto an agar plate to see if
microbial colonies will grow
invasion dissemination of a pathogen
through local tissues or throughout the
body
iodophor compound in which iodine is
complexed to an organic molecule,
increasing the stability and efficacy of
iodine as a disinfectant
ionizing radiation high-energy form of
radiation that is able to penetrate surfaces
and sterilize materials by damaging
microbial cell components and DNA
ischemia condition marked by the
inadequate flow of blood to the tissues
isograft tissue grafted from one
monozygotic twin to another
isohemagglutinins IgM class antibodies
produced against A or B red blood cell
antigens
isomers molecules that have the same
atomic makeup but differ in the structural
arrangement of the atoms
isoniazid antimetabolite that inhibits
biosynthesis of mycolic acid; used for the
treatment of mycobacterial infections
isoprenoid branched lipid derived from
five-carbon isoprene molecules
isotonic medium a solution in which the
solute concentrations inside and outside
the cell are approximately equal, thereby
creating no net movement of water
molecules across the cell membrane
ivermectin antihelminthic drug of the
avermectin class that binds to invertebrate
glutamate-gated chloride channels to
block neuronal transmission in helminths
J
Japanese encephalitis arboviral disease
caused by the Japanese encephalitis virus
(JEV) and endemic to Asia
jaundice yellowish color of the skin and
mucous membranes caused by excessive
bilirubin caused by a failure of the liver to
effectively process the breakdown of
hemoglobin
K
karyokinesismitotic nuclear division
keratin a fibrous protein found in hair,
nails, and skin
keratitis inflammation of the cornea
keratoconjunctivitis inflammation of
both the cornea and the conjunctiva
kidney organ that filters the blood,
producing urine
Kinyoun technique a method of acid-fast
staining that does not use heat to infuse
the primary stain, carbolfuchsin, into
acid-fast cells
Kirby-Bauer disk diffusion test simple,
rapid method for determining
susceptibility and resistance of a bacterial
pathogen to antibacterial drugs. The test
involves drug-impregnated disks placed
on an agar plate inoculated with a
bacterial lawn.
Koplik’s spots white spots that form on
the inner lining of the cheek of patients
with measles
Krebs cycle cyclic pathway during which
each two-carbon unit entering the cycle is
further oxidized, producing three NADH,
one FADH 2 , and one ATP by substratelevel
phosphorylation, releasing two CO 2
molecules and regenerating the molecule
used in the first step; also called the citric
acid cycle or the tricarboxylic acid cycle
kuru rare form of transmissible
spongiform encephalopathy endemic to
Papua New Guinea
L
lacrimal duct connects the lacrimal gland
to the lacrimal sac
lacrimal gland a gland situated above the
eye that secretes tears
lacrimal punctum opening in each upper
and lower eyelid
lacrimal sac a to a reservoir for tears; also
known as the dacrocyst or tear sac
lag period the time between antigen
exposure and production of antibodies
lag phase interval before exponential
growth of a microbial population during
which cells adjust to a new environment
lagging strand strand of DNA made
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