AN OVERVEIW
Species in genus Clostridium are phylogenetically classified in domain: bacteria; kingdom: prokaryotae; phylum: firmicutes; class: clostridia; order: clostridiales and genus: Clostridium
An estimate of over 100 species of genus Clostridium has been isolated world-wide. Species in Genus Clostridium are gram positive, spore forming peritrichous rod-like bacteria.
Habitat:
They are found predominantly in soil, water and decaying organic matters
DIVISION OF SPECIES OF GENUS CLOSTRIDIUM
The species of this genus is best divided into the following
- Free-living/ commensals Clostridium species
- Commercial important Clostridium species
- Medically important Clostridium species
Free-living/Commensals Clostridium
Examples of free-living Clostridium species include: Clostridium cellobioparum and Clostridium ramosum. These microorganisms are found in the gut of ruminants such as cattle, sheep, goat as well as in the stomach of humans and termites. The gut of humans and other ruminant livestock serves as shelter for them. They in return produce enzymes such as cellulose and lignin. This help is the breakdown of complex carbohydrate organic matters in the gut and thus aid digestion in humans and livestock.
Clostridium of commercial importance
Clostridium acetobutylicum was utilized in the production in the production of acetone and biobutanol from starch which are used in the producing cordite used by smokeless gun powder. Enzymes such as collagenase, protease, lipase have been reported to be produced commercially by using Clostridium histolyticum. On the other hand Clostridium thermocellum has been used in the production of ethanol fuel from liginocellulosic waste. Biofuels such as biomethane and bio ethanol have been produced from commercial purposes in countries such as Brazil and India from organic waste by using Clostridium ijungdahlii,
Clostridium species of Medical Importance
Clostridium colinum has been implicated to be the causal agent of enteric ulcer in chickens while Clostridium novyi, Clostridium botulinum, Clostridium perfringens, Clostridium tetani are the common human pathogens. Clostridium novyi is known to be cause food poisoning which is characterized with mild abdominal cramp, nausea and vomiting.
Clostridium: the ruin of war casualties
The portrait above was drawn by Charles Bell, an English anatomist in 1809 depicting a wounded soldier dying of tetanus. During the Napoleonic war in Europe as well as the first world war, most wounded soldiers were damn to die of tetanus due to the insufficiently knowledge of antiseptic principles as well as lack of potent antimicrobial drug as at then. Upon the discovery of antiseptic surgery by Joseph Lister 1867 and 20th century miracle antimicrobial drug called penicillin by Alexander Fleming in 1927, the cases of tetanus subsided.
Epidemiology
Table 1: Botulism Cases between 1920-2014 world wide
| Countries | Outbreaks
(197 Cases) |
Percent (%)
|
| USA | 109 | 55 |
| Canada | 29 | 15 |
| Europe | 25 | 13 |
| Asia | 22 | 11 |
| Africa | 6 | 3 |
| Others | 6 | 3 |
| Exposure Sources | ||
| Commercial | 52 | 26 |
| Non-commercial
(Home canned) |
83 | 42
|
| Non-commercial (Others) | 50 | 25 |
| Unclear | 12 | 6 |
| Toxin Types | ||
| A | 66 | 34 |
| B | 31 | 16 |
| C | 34 | 17 |
| F | 2 | 1 |
| E | 34 | 17 |
| Unclear | 64 | 32 |
An estimate of 197 cases of botulism were reported between the year 1920 to 2014. 55, 15, 13, 11 and 3 percent of the occurrence of botulism were recorded in USA, Canada, Europe, Asia and Africa respectively. 26 and 42 percentage were from commercial canned foods and home canned food respectively. Type A botulism toxin was implicated to cause the highest cases of botulism world-wide with about 45 percent.
Epidemiology Clostridium perfringens infection
Clostridium perfringens infection is predominant in the United States. About 1,000 cases of gas gangrene are reported yearly in the United States (Source: Jerrold, 2018)
Epidemiology of tetanus
About 10,000 to 20,000 cases of tetanus were reported in Nigeria in 1990 and 2005, while there was a drastic decrease to about 1,000 to 10,000 cases in 2017. The figure below represents the range of tetanus infection world-wide in year 1990, 2005 and 2017
PATHOGENESIS
CLOSTRIDIUM PERFRINGENS ALPHA TOXINS
Mechanism of action
- perfringens are taken in by humans via contaminated undercooked foods. It can survive and live in the intestine without causing harm until the infective dose reaches about 106 cells. The bacteria releases enterotoxins which causes shedding of the intestinal mucosa thus leading to intestinal cramps and coupled with nausea, vomiting and profuse stooling.
Clostridium perfringens bacteria are anaerobic and are present in the soil. When the wound of an individual becomes infected with C. perfringens. These bacteria try to create anaerobic in the subcutaneous condition in the tissue. The fermentative activities coupled with alpha toxins production of Clostridium perfringens in the subcutaneous layer leadings to painful inflammation of the layer, followed by filling of the layer with bloody exudate and gas. This inflamed area bursts open soon after and if proper treatment is not administered lead to more inflammation and severe tissue damage.
Symptoms of Clostridium perfringens infection
- Abdominal cramp
- Fever
- Nausea
- Vomiting
- Necrosis of the body tissues
BOTULINUM TOXIN
Mechanism of action
There are five types of toxins produced by Clostridium botulinum: A, B, C, D, E, F. Toxin A is the most virulent or toxic of all the toxins produced by Clostridium botulinum. The toxins is responsible for the enteritis in humans. When contaminated canned food is ingested with either the vegetative cells or the spore of Clostridium botulinum. Spores sporulate in intestine into vegetative cells, this encouraged by a series of enzymatic activities and physiochemical conditions of the intestine. The vegetative cells strive in the intestine, produces toxins which leads to the inflammation of the intestine and subsequent fluidity of the intestinal mucosal thus leading to nausea, diarrhea. The toxins can also get into the blood stream, goes to the nervous system and interferes with the passage of a neurotransmitter called acetycholine. This leads to blurred vision, lowering of eyelid and fatigue.
Symptoms of Botulism
The symptoms of botulism include:
- Blurred vision
- Dropping eyelids
- Dry mouth and speaking problem
- Nausea
- Vomiting
- Abdominal cramp
TETANUS TOXIN
Poorly managed wound could become infected with Clostridium tetani. When this happens, the toxin called tetanospasmin released by Clostridium tetani. The toxin blocks the passage of neurotransmitters called GABA (Gamma- aminobutyric acid) and glycine along the nerve, thus leading to spasm (stiffness of the body muscles), fatigue and lockjaw.
Symptoms of Tetanus
- Lockjaw
- Spasm (Muscle stiffness)
- Fatigue
- Fever
- Loss of weight
- Loss of Appetite
DIAGNOSIS CLOSTRIDIUM INFECTION
Diagnosis of Clostridium perfringens
Laboratory diagnosis of C. perfringens food poisoning is by detecting a type of bacterial toxin in feces or by tests to determine the number of bacteria in the feces. A count of at least 106 cells which is the infective dose of C. perfringens spores per gram of stool within 48 hours of when illness began is required to diagnose infection. This is due to the fact that C. perfringens can also be harmless and free-living in the intestine of humans and animals. Thioglycolate medium or Lactose-gelatin medium or blood agar or Sulphite polymixin agar are often used in culturing the bacteria under anaerobic condition. Wound swab can also be obtain from infected sites and cultured.
Diagnosis of Botulism and Tetanus
Physical observation by the physician based on signs and symptoms exhibited by the patient is a primary diagnosis technique used by physicians. However, culturing of patients stool samples on Thioglycolate medium, lactose-gelatin medium, casein hydrolysate media and /or blood agar under anaerobic condition have proven effective in their isolation.
Endospore Staining
A confirmatory test called endospore staining using the malachite green, primary stain and safranin the secondary stain help to ascertain if the isolated infectious species is Clostridium
Microscopy
The use of microscope for the observation of the spoecies that retain green (spore) or pink (non spore formers) as when as in the observation of the bacterial shape after gram staining.
16s RNA sequencing
This molecular method is the best and the most efficient method identifying species of Clostridium.
Treatment of Botulism
Intraveous Botulinum antitoxin injected as well as the use of antibiotics such as penicillin and erythromycin as prescribed by physician according to the severity of the infection is used for the treatment of botulism.
Treatment of Clostridium perfringens Infection
Diarrhea from C. perfringens is self-limiting, infected individuals can recover after weeks of infection without treatment. But oral rehydration or in severe cases, intravenous fluids and electrolyte replacement can be used to prevent or treat dehydration. Antibiotics are not recommended. However, proper wound management should be encouraged for case of tissue necrotic in gas gangrene, anti-toxin therapy which help in the neutralization of C. perfringens alpha toxins and in severe cases surgery is highly recommended.
Treatment of Tetanus
Tetanus antitoxin (tetanus toxoid) injection is used in the neutralization of the C. tetani toxins in the body. This is often coupled with antibiotics such as penicillin and erythromycin. However, dosage is prescribed by taking the age and weight of infected individuals into cognizant.
PREVENTION AND CONTROL OF CLOSTRIDIA INFECTIONS
- Good personal hygiene
- Immunization of new born and adults
- Proper diagnosis
- Proper wound management
- Good manufacturer practices
- Avoidance of undercooked foods
LATEST DISCOVERY: CLOSTRIDIUM SPECIES AND MENTAL HEALTH
Clostridium difficile was reclassified to genus Clostrioides. This bacterium is now called Clostrioides difficile. Clostridium difficile Infection (CDI) has been reported to be prominent in people with depression. This is probably due to lowered immune system in depressed people.
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