''Clostridium innocuum'' is an

anaerobic Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: * Anaerobic adhesive, a bonding a ...

non-motile Sessility is the biological property of an organism describing its lack of a means of self-locomotion. Sessile organisms for which natural ''motility'' is absent are normally immobile. This is distinct from the botanical concept of sessility, ...

gram-positive bacterium In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bacte ...

that reproduces by

sporulation In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...

. While there are over 130 species of Clostridium, ''C. innocuum'' is the third most commonly isolated. Although it is not normally considered an aggressive

human pathogen A human pathogen is a pathogen (microbe or microorganism such as a virus, bacterium, prion, or fungus) that causes disease in humans. The human physiological defense against common pathogens (such as ''Pneumocystis'') is mainly the responsibility ...

, it has been isolated in some disease processes. ''C. innocuum'' and other Clostridium line the

oropharynx The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its struct ...

and

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 are considered normal

gut flora Gut microbiota, gut microbiome, or gut flora, are the microorganisms, including bacteria, archaea, fungi, and viruses that live in the digestive tracts of animals. The gastrointestinal metagenome is the aggregate of all the genomes of the gut mi ...

Characteristics and identification

Anaerobic gram-positive bacilli affecting human beings are generally divided into two distinct groups, those that form spores (''Clostridium'' spp) and those that do not form spores. Within the spore-forming group of ''Clostridium'' species, some are very

pathogenic In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

or toxigenic (''

C. perfringens ''Clostridium perfringens'' (formerly known as ''C. William H. Welch, welchii'', or ''Bacillus welchii'') is a Gram-positive, rod-shaped, anaerobic bacterium, anaerobic, Endospore, spore-forming pathogenic bacterium of the genus ''Clostridium''. ...

'') while others are rarely pathogenic. Identification and differentiation between anaerobic gram-positive bacteria in a clinical laboratory can be a very difficult task. ''Clostridium innocuum'' forms white, glossy, raised

colonies In modern parlance, a colony is a territory subject to a form of foreign rule. Though dominated by the foreign colonizers, colonies remain separate from the administration of the original country of the colonizers, the '' metropolitan state'' ...

and exhibits a chartreuse fluorescence. It is a small, non-motile rod that does not swarm. ''C. innocuum'' falls into the saccharolytic, non-proteolytic group of Clostridium spp. and is negative for gelatin hydrolysis, lecithinase, lipase, indole, urea, and nitrate. It is positive for glucose fermentation, esculin and produces oval, terminal spores.

Pathology

Although ''Clostridium innocuum'' are often present and harmless in healthy people, they have been isolated in various infections and predominantly in patients that are

immunocompromised Immunodeficiency, also known as immunocompromisation, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that a ...

as an opportunistic bacteria. In one case, ''C. innocuum'' was isolated in an infected hematoma adjacent to a transplanted kidney in a 38-year-old hepatitis C patient. Originally, the bacteria was misidentified as another ''Clostridium'' species but was eventually correctly identified. This led the authors to state that ''C. innocuum'' infection post transplant may be severely underestimated. ''C. innocuum'' has also been implicated in cases of fatal bacteremia as reported in a retrospective study done by

Newark Beth Israel Medical Center Newark Beth Israel Medical Center (NBIMC), previously Newark Beth Israel Hospital, is a 665-bed quaternary care, teaching hospital located in Newark, New Jersey serving the healthcare needs for Newark and the Northern Jersey area. The hospital is ...

. Patients that succumbed to the infection (100% mortality) had underlying disease states (

malignancy Malignancy () is the tendency of a medical condition to become progressively worse. Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...

diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...

liver The liver is a major Organ (anatomy), organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of proteins and biochemicals necessary for ...

disease). While clostridial species only account for 2% of clinical bacteremia, ''C innocuum'' was among the three most commonly isolated bacteria in this study. ''C. innocuum'' has also been isolated in patients with recurrent

diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin wi ...

who had prior ''C. difficile'' associated diarrhea. One case of fatal bacterial

endocarditis Endocarditis is an inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves. Other structures that may be involved include the interventricular septum, the chordae tendineae, the mural endocardium, or the ...

was also found in the literature. This is possibly the only confirmed case of ''C. innocuum'' endocarditis involving the pulmonary and tricuspid valves resulting in multiple emboli and death.

Drug resistance

In a study that identified clostridial species using commercial identification kits, it was found that as many as 10% of ''C. innocuum'' isolates were somewhat resistant to clindamycin. Most strains were found to be only moderately susceptible to vancomycin (MIC at which 90% of strains are inhibited, 4 micrograms/mL). In another study, where ''C innocuum'' was positively identified by

gas-liquid chromatography Gas chromatography (GC) is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of a particular substance, ...

, resistance to vancomycin was seen in all 28 strains isolated. All other clostridial species were at least 8 times more susceptible to vancomycin than ''C. innocuum'', suggesting an intrinsic vancomycin resistance mechanism in ''C. innocuum''.

References

External links

* * *
Type strain of ''Clostridium innocuum'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{Taxonbar, from=Q3681087 Gram-positive bacteria Bacteria described in 1962 innocuum