Insights into Anaerobic Bacteria

Anaerobic bacteria do not replicate in the presence of oxygen. Three categories of anaerobic bacteria include obligate anaerobes, aerotolerant anaerobes, and facultative anaerobes. While most species are obligate anaerobes, some can survive under aerobic conditions and are aerotolerant. There are almost 200 species of Clostridium, with a few being pathogenic to humans.

Clostridia: General Characteristics

Habitat

Present in soil, water, and various moist environments across the earth, for example, some plant roots. They also live in human bodies (flora of intestines) and animal bodies.

Growth

Reproduces by binary fission. The round strand of DNA starts replicating, and the cell lengthens as the new copies of DNA move to opposite poles of the cell. Replication ends, and the cell resumes growth. The plasma membrane starts to invaginate, and a new cell wall appears. The outcome is two identical daughter cells.

Genome

Single circular chromosome with millions of base pairs and a round plasmid with seven thousand base pairs. About 11% of the genome consists of transposons, mobile DNA segments that can travel within the genome.

Movement

Moves with peritrichous flagella, uniformly spread across the surface of the cell, providing motility to the bacteria.

Nutrition

Heterotrophic, relying on organic sources for nutrition. They obtain energy for Adenosine Triphosphate through fermentation and acquire nutrients from dead plants and animals in soil.

C. Tetani: Tetanus

Symptoms

Bloody stools, diarrhea, headache, general muscle ache, sweating, increased heartbeat, lockjaw, difficulty swallowing, respiratory failure, and neuronal inactivation. Tachycardia is also observed.

Cause

Tetanus infection is produced by contamination of a wound with causative bacteria, C. tetani. The anaerobic tissue environment facilitates C. tetani replication and secretion of exotoxins. The powerful toxin tetanospasmin fixes to inhibitory neurons, blocking the release of neurotransmitters and impairing nerves that control motor neurons.

Pathophysiology

Tetanus toxin gains access to nerve terminals through lower motor neurons, affecting voluntary muscular movements. It progresses via axons to the spinal cord and brainstem, then trans-synaptically into nerve terminals responsible for releasing inhibitory neurotransmitters.

Diagnosis

Established primarily on a physical exam, clinical symptoms, medical and vaccination history. The wound may not be distinct, and C. tetani is retrieved from one-third of all infected wounds.

Prevention

Administration of tetanus toxoid is a preventive action, providing protection through vaccination.

Treatment

There is no cure for tetanus. Treatment involves wound debridement, medications (antitoxin, antibiotics, vaccine, and sedatives) to reduce symptoms, and supportive therapy.

C. Botulinium: Botulism

Symptoms

Vomiting, diarrhea, blurred vision, difficulty swallowing, difficulty breathing, muscle weakness, dry mouth, respiratory failure, nausea, and potential death.

Cause

Several factors can cause botulism, including food consumption containing botulinum toxin, wound entry, inhalation, consumption by newborns, intestinal colonization, and iatrogenic (overdose of clinical and cosmetic botox).

Pathophysiology

Mechanism involves toxin-mediated blockage of neuromuscular communication in cholinergic nerve fibers. Toxins are ingested from the gut and stomach, enter through skin breakage, and hematogenously disperse, preventing neuromuscular communication in cholinergic nerve fibers.

Diagnosis

Clinical history and examination, toxin identification, brain scans, lumbar puncture, electromyography, and blood tests.

Prevention

Vaccination, proper cooking of food, refrigeration, checking food expiration dates, maintaining a safe cooking environment, and ensuring good personal hygiene.

Treatment

Hospitalization, ventilator support, injections with antitoxins, surgical treatment of wounds, antibiotics for secondary infection.

C. Perfringens: Cellulitis

Symptoms

Redness and inflammation, fever, blisters, swelling, fatigue, increased temperature, pain, rash, sweating.

Cause

Injury (cuts or cracks in the skin), long-term skin diseases, lymphedema, obesity, compromised immune system.

Pathophysiology

Breach in the skin allows organisms on the skin to enter the dermis and replicate, causing cellulitis. Mainly caused by Streptococcus.

Diagnosis

Physical examination of affected areas, lymph nodes, and skin condition.

Prevention

Good personal hygiene, protection of wounds, treatment of superficial infections, maintaining overall skin health.

Treatment

Rest affected area, clean and protect wounds, oral or IV antibiotics, cryotherapy on affected area, raise affected limb, surgery if necessary.

C. perfringens: Gas Gangrene

Symptoms

Gas bubbles, vomiting, raised temperature, swelling, sweating, pain around the affected area, discoloration of the skin.

Cause

Deep wounds, injured tissue, open fractures, muscle damage, colon cancer, diabetes.

Pathophysiology

Created by spore-forming bacillus, organisms are true saprophytes, producing gas, and approximately 20 exotoxins.

Diagnosis

Skin culture test, blood work, X-ray, MRI, surgery.

Prevention

Proper personal hygiene, protection of wounds, antibiotics to prevent infection, avoiding tobacco, maintaining a healthy lifestyle and BMI.

Treatment

High doses of antibiotics, surgical removal of affected tissue, amputation if necessary, hyperbaric oxygen therapy.

References

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