''Klebsiella aerogenes'', previously known as ''Enterobacter aerogenes,'' is a
Gram-negative
Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall ...
,
oxidase
In biochemistry, an oxidase is an enzyme that catalyzes oxidation-reduction reactions, especially one involving dioxygen (O2) as the electron acceptor. In reactions involving donation of a hydrogen atom, oxygen is reduced to water (H2O) or hydro ...
negative,
catalase
Catalase is a common enzyme found in nearly all living organisms exposed to oxygen (such as bacteria, plants, and animals) which catalyzes the decomposition of hydrogen peroxide to water and oxygen. It is a very important enzyme in protecting t ...
positive,
citrate
Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in t ...
positive,
indole
Indole is an aromatic heterocyclic organic compound with the formula C8 H7 N. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered pyrrole ring. Indole is widely distributed in the natural environmen ...
negative,
rod-shaped
A bacillus (), also called a bacilliform bacterium or often just a rod (when the context makes the sense clear), is a rod-shaped bacterium or archaeon. Bacilli are found in many different taxonomic groups of bacteria. However, the name ''Bacillu ...
bacterium
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
. The bacterium is approximately 1-3 microns in length, and is capable of motility via peritrichous flagella.
''Klebsiella aerogenes'' is a
nosocomial
A hospital-acquired infection, also known as a nosocomial infection (from the Greek , meaning "hospital"), is an infection that is acquired in a hospital or other health care facility. To emphasize both hospital and nonhospital settings, it is ...
and
pathogenic bacterium
Pathogenic bacteria are bacteria that can cause disease. This article focuses on the bacteria that are pathogenic to humans. Most species of bacteria are harmless and are often beneficial but others can cause infectious diseases. The number of t ...
that causes
opportunistic infection
An opportunistic infection is an infection caused by pathogens (bacteria, fungi, parasites or viruses) that take advantage of an opportunity not normally available. These opportunities can stem from a variety of sources, such as a weakened immune ...
s including most types of infections. The majority are sensitive to most antibiotics designed for this bacteria class, but this is complicated by their inducible resistance mechanisms, particularly
lactamase
Beta-lactamases, (β-lactamases) are enzymes () produced by bacteria that provide multi-resistance to beta-lactam antibiotics such as penicillins, cephalosporins, cephamycins, monobactams and carbapenems (ertapenem), although carbapenem ...
, which means that they quickly become resistant to standard antibiotics during treatment, requiring a change in antibiotic to avoid worsening of the
sepsis
Sepsis, formerly known as septicemia (septicaemia in British English) or blood poisoning, is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage is follo ...
.
Some of the infections caused by ''K. aerogenes'' result from specific
antibiotic
An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...
treatments,
venous catheter
In medicine, a peripheral venous catheter, peripheral venous line, peripheral venous access catheter, or peripheral intravenous catheter, is a catheter (small, flexible tube) placed into a peripheral vein for venous access to administer intraven ...
insertions, and/or surgical procedures. ''K. aerogenes'' is generally found in the human
gastrointestinal tract
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organ (biology), organs of the digestive syste ...
and does not generally cause disease in healthy individuals. It has been found to live in various wastes, hygienic chemicals, and soil. The bacterium also has some commercial significance – the hydrogen gas produced during fermentation has been experimented with using
molasses
Molasses () is a viscous substance resulting from refining sugarcane or sugar beets into sugar. Molasses varies in the amount of sugar, method of extraction and age of the plant. Sugarcane molasses is primarily used to sweeten and flavour foods ...
as the substrate.
''K. aerogenes'' is an outstanding hydrogen producer. It is an anaerobic facultative and mesophilic bacterium that is able to consume different sugars and in contrast to cultivation of strict anaerobes, no special operation is required to remove all oxygen from the fermenter. ''K. aerogenes'' has a short doubling time and high hydrogen productivity and evolution rate. Furthermore, hydrogen production by this bacterium is not inhibited at high hydrogen partial pressures; however, its yield is lower compared to strict anaerobes like ''Clostridia''. A theoretical maximum of 4 mol H2/mol glucose can be produced by strict anaerobic bacteria. Facultative anaerobic bacteria such as ''K. aerogenes'' have a theoretical maximum yield of 2 mol H2/mol glucose.
It may spoil maple sap and syrup.
Owing to diverse metabolites, namely acids and alcohols, produced by such a strain in conjunction with its capability of utilizing different sugars, the metabolic behavior and growth of ''K. aerogenes'' can significantly vary under different conditions.
Biochemical identification test results
References
External links
*
*
Type strain of ''Klebsiella aerogenes'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{Taxonbar, from=Q644487
Enterobacteriaceae
Bacteria described in 1960