''Cardiobacterium hominis'' is a
Gram-negative bacillus (rod-shaped)
bacterium commonly grouped with other bacteria into the
HACEK group. It is one of several bacteria that is normally present in the mouth and upper part of the
respiratory tract
The respiratory tract is the subdivision of the respiratory system involved with the process of respiration in mammals. The respiratory tract is lined with respiratory epithelium as respiratory mucosa.
Air is breathed in through the nose to th ...
such as nose and throat. However, it may also rarely cause
endocarditis, an infection of the
heart valves.
Microbiology
''C. hominis'' is a
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 ...
-negative,
oxidase-positive,
indole-producing, Gram-negative
rod
Rod, Ror, Ród, Rőd, Rød, Röd, ROD, or R.O.D. may refer to:
Devices
* Birch rod, made out of twigs from birch or other trees for corporal punishment
* Ceremonial rod, used to indicate a position of authority
* Connecting rod, main, coupling, ...
.
Its morphology has classically been described as highly pleomorphic and irregularly staining, although homogeneous bacilli with uniform shapes may be seen with the addition of
yeast extract.
Antibiotic sensitivity
Historically, ''C. hominis'' has been sensitive to
penicillin
Penicillins (P, PCN or PEN) are a group of β-lactam antibiotics originally obtained from ''Penicillium'' moulds, principally '' P. chrysogenum'' and '' P. rubens''. Most penicillins in clinical use are synthesised by P. chrysogenum using ...
and penicillin derivatives such as
ampicillin.
However, penicillin-resistant strains, including those that produce
beta-lactamases, have been described with increasing frequency.
Clinical guidelines thus recommend that ''C. hominis'' and other HACEK organisms be presumed to harbor ampicillin resistance and therefore be treated with a third-generation
cephalosporin
The cephalosporins (sg. ) are a class of β-lactam antibiotics originally derived from the fungus ''Acremonium'', which was previously known as ''Cephalosporium''.
Together with cephamycins, they constitute a subgroup of β-lactam antibiotics ...
.
''C. hominis'' and other HACEK organisms also exhibit ''in vitro'' susceptibility to
trimethoprim-sulfamethoxazole,
fluoroquinolones, and
aztreonam.
''C. hominis'' is often resistant to
erythromycin
Erythromycin is an antibiotic used for the treatment of a number of bacterial infections. This includes respiratory tract infections, skin infections, chlamydia infections, pelvic inflammatory disease, and syphilis. It may also be used duri ...
.
Since cefotaxime use may be not appropriate for ''C. hominis'' endocarditis, an alternative regimen might include association of co-amoxiclav and gentamicin.
References
External links
Image: ''Cardibacterium hominins''Type strain of ''Cardiobacterium hominis'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{Taxonbar, from=Q2938074
Gram-negative bacteria
Gammaproteobacteria