Bacteriology

Clostridium botulinum and Francisella tularensisGROUP 4BacteriologyFrancisella tularesisA pathogenic species of Gram-negative bacteria and the causative agent of tularemia, the pneumonic form of which is often lethal without treatment.It is a fastidious,facultative intracellular bacterium which requires cysteine for growth.

Mode of transmissionTularemia is usually spread to humans by insect bites from ticks and deerflies.Direct exposure to infected animals such as rodents, rabbits and hares. Consuming contaminated foods and water.Tularemia is also airborne.

Signs and SymptomsAbrupt onset of fever and chills - These symptoms typically last for several days, remit for a brief interval, and then recurPulse-temperature disassociationHeadacheAnorexiaMalaise and fatigue or prostrationMyalgiasCoughVomitingPharyngitisAbdominal painSecondary pneumonitisDiseasesUlceroglandular tularemia - Includes painful regional lymphadenopathy and an ulcerated skin lesionGlandular tularemia - Tender lymphadenopathy without evidence of local cutaneous lesionsOculoglandular tularemia - Unilateral conjunctivitis, corneal ulceration, lymphadenopathy, photophobia, lacrimation, lid edema, vision loss (rare)Oropharyngeal tularemia - Stomatitis and exudative pharyngitis or tonsillitis; abdominal pain, nausea, and vomiting; cervical lymphadenopathy; diarrhea; gastrointestinal bleedingPneumonic tularemia - Dry cough, dyspnea, and pleuritic-type chest painTyphoidal tularemia - Fever, chills, myalgias, malaise, and weight loss

Microscopic view of Francisella tularensis

Culture media Francisellastrains requiring cystineand cysteinemedia supplementation for growth. Growth has been successful on several media types, includingchocolate agarandThayer-Martinmedia with appropriate additives as noted above. Attempted isolation onMacConkey agarisnotreliable or generally successful.Clostridium botulinumA Gram-positive, rod-shaped, anaerobic, spore-forming, motile bacterium with the ability to produce the neurotoxin botulinum.The botulinum toxin can cause a severe flaccid paralytic disease in humans and animals and is the most potent toxin known to humankind, natural or synthetic, with a lethal dose of less than 1 g in humans.Mode of transmissionClassical botulism is acquired by ingestion of inadequately cooked food.Wound botulism are due to ground-in soil or gravel.Infant botulism arises from ingestion of spores (foods such as honey and dust) rather than pre-formed toxin.Signs,Symptoms and DiseasesFoodborne botulism- Results from ingestion of preformed neurotoxins, commonly from foods that placed in anaerobic storage such as in cans or jars.Double visionBlurred visionDrooping eyelidNausea, vomiting, and abdominal crampsSlurred speechTrouble breathingDifficulty in swallowingDry mouthMuscle weaknessConstipationReduced or absent deep tendon reactions, such as in the knee.

Infant/Intestinal botulism- Usually affects infants and rarely, adults with altered gastrointestinal anatomy or microflora. It is caused by ingesting spores of the botulinum bacteria that multiply in the gut and produce the toxin.

Constipation (often the first sign)Floppy movements due to muscle weakness and trouble controlling the headWeak cryIrritabilityDroolingDrooping eyelidsTirednessDifficulty sucking or feedingParalysis

Wound botulism- Occurs when an open wound is contaminated with botulinum spores.

Difficulty swallowing or speakingFacial weakness on both sides of the faceBlurred or double visionDrooping eyelidsTrouble breathingParalysis

Clostridium botulinumis usually isolated in tryptose sulfitecycloserine(TSC) growth media in an anaerobic environment with less than 2% of oxygen. This can be achieved by several commercial kits that use a chemical reaction to replace O2with CO2.C. botulinumis alipasepositive microorganism that grows betweenpHof 4.8 and 7 and can not use lactoseas a primary carbon source, characteristics important during a biochemical identification. Culture mediaMicroscopic images of Clostridium botulinum