anaerobes and anthrax

Clostridial diseasesAnthrax

Clostridial diseases

● Clostridium spp. ● Gram positive rods● Obligate anaerobes● Endospore forming

Clostridium spp.

● Endospores● Resistant to:● Heat● Disinfectants

Clostridium spp.

● Soil (found on just about all environmental surfaces)

● Fecal matter of humans and animals

● Aquatic sediments

Clostridium spp. (obligate anaerobes)

● Rapidly killed by highly reactive oxygen radicals● Singlet oxygen● Superoxide free radicals

The Clostridia genus● The clostridia produce a wide variety of

extracellular enzymes to degrade large biological molecules in the environment into fermentable components

● Hence, the clostridia play an important role in nature in biodegradation and the carbon cycle

● In anaerobic clostridial infections, these enzymes play a role in invasion and pathology

Grown in the laboratory under anaerobic conditions

Who are the Clostridia’s?

● Most of the clostridia are saprophytes but a few are pathogenic for humans

● Those that are pathogens have primarily a saprophytic existence in nature and, in a sense, are opportunistic pathogens

● Clostridium tetani and Clostridium botulinum produce the most potent biological toxins known to affect humans

Clostridium perfringens● C. perfringens produces a huge array of invasins

and exotoxins, causes wound and surgical infections that lead to gas gangrene, in addition to severe uterine infections.

● Clostridial hemolysins and extracellular enzymes such as proteases, lipases, collagenase and hyaluronidase, contribute to the invasive process

● C. perfringens also produces an enterotoxin and is an important cause of food poisoning.

● Usually C. perfringens and C. botulinum is encountered in improperly sterilized (canned) foods in which endospores have germinated

Clostridium difficile

● Pseudomembranous colitis in humans is caused by overgrowth ofClostridium difficile in the colon, usually after the normal flora has been disturbed by antimicrobial chemotherapy.

● C. difficile produces two toxins: Toxin A is referred to as an enterotoxin because it causes fluid accumulation in the bowel

● Toxin B is an extremely lethal (cytopathic) toxin.

Clostridium tetani● Clostridium tetani is the causative agent of

tetanus. ● The organism is found in soil, especially heavily-

manured soils, and in the intestinal tracts and feces of various animals.

● Carrier rates in humans vary from 0 to 25%, and the organism is thought to be a transient member of the flora whose presence depends upon ingestion.

● The organism produces terminal spores within a swollen sporangium giving it a distinctive drumstick appearance.

● Although the bacterium has a typical Gram-positive cell wall, it may stain Gram-negative or Gram-variable, especially in older cells.

Neutralization of oxygen radicals

● Superoxide Dismutase (SOD)

● Catalase● Clostridium spp. lacks these

enzymes

Clostridium spp.

● C. tetani● C. botulinum● C. perfringens● C. difficile

Clostridium tetani“Drumstick” appearance

Clostridial diseases

● Tetanus● Botulism● Gas gangrene● Foodborne gastroenteritis● Pseudomembrane colitis

TETANUS

● Localized infection, caused by a C.tetani toxin

● General muscle spasms-due to neurotoxin

● Trauma (often trivial)● Chronic skin ulcers● Umbilical cord (clay

matter ritual in Africa)● Abortion (unsanitary

abortions)

TETANUS (cont.)

TETANUS (cont.)● 300,000/year world wide● 100 cases/year in the USA (24

fatal)● 70% unvaccinated, or

incomplete vaccination regime

● Mostly 60 years and older

TETANUS (cont.)

● Spores in wound● Infection and/or tissue

necrosis● Low O2 tension ● Spore germination

TETANOSPASMIN

● Blocks the muscle relaxation pathway

● Death results from spasms of respiratory muscles

● Released from dead bacterial cells

TETANOSPASMIN (cont.)

● Once it attaches to nerves, therapy is usually ineffective

Advanced case of tetanus

Greek tetanos, to stretch

TREATMENT OF TETANUS

● Removal of necrotized (death) tissue

● Antibiotics● Human

immunoglobulins

TETANUS VACCINE

-S-S-

Toxin Toxoid

Active Inactive

Enzyme

TETANUS VACCINATION SCHEDULE (CDC)

● DTaP vaccine (Diptheria, Tetanus & acellular pertussis)

● 2, 4, 6 and 12-18 months● 4-6 years

FOODBORNE BOTULISM

● A non-infectious food poisoning

● C. botulinum neurotoxin in contaminated food

● 34 cases in 1994 (USA)

FOODBORNE BOTULISM (cont.)

BOTULIN TOXIN

● Most potent of all natural toxins● Approx. 0.001 mg human

lethal dose● Causes flaccid paralysis● Death follows cardiac failure

Definitive Diagnosis

● only establish with toxin identification:● Isolation of toxigenic cultures and

identification of the involved type C or D toxin with the aid of serum neutralization in mice or guinea-pigs.

● Toxin detection in clinical samples collected for laboratory analysis (intestinal contents)

Type of tests to ID botulism● tests may include a brain scan, spinal fluid

examination, nerve conduction test (electromyography, or EMG),

● The most direct way to confirm the diagnosis is to demonstrate the botulinum toxin in the patient's serum or stool by injecting serum or stool into mice and looking for signs of botulism

● The bacteria can also be isolated from the stool of persons with foodborne and infant botulism

● These tests can be performed at some state health department laboratories and at CDC

BOTULIN TOXIN (cont.)

● Home preserves (pH 5 and above) frequent source of botulism

● Not formed in pH below 4.7● Molds may shift pH to above 4.7● Destroyed by boiling 10 min● Treatment of Botulism NONE

BOTULISM PREVENTION● Preservation of foods at pH below

4.7● Salt (brine) and sugar● Nitrites in cured foods (remember

the nitrites/nitrates in hot dogs, cured ham, processed meats)

● Boiling food 10 min

INFANT BOTULISM

● Predominant form in the USA● 75-100 cases/year in the USA

INFANT BOTULISM (cont.)● Less than 6 months old children● Associated with ingestion of honey● Honey has endospores in it

naturally bees pick up the endospores from the flowers

● Immature intestinal microflora of infants leads to infant botulism

● children may receive medical attention because of symptoms such as constipation, poor sucking action, a weak cry, and a general, progressive muscle weakness.

Infant botulism detection tests!!

● The diagnosis is confirmed by the detection of the organism or its toxin in the infant’s stool

● Toxin isolation and identification are accomplished via mouse lethality testing, with typing (type C or D toxin) confirmed by neutralization of toxin by specific sera (antibodies—immunoglobulins)

Where are these endospores commonly found?

● More than 90% of reported cases (infant botulism) in the USA come from California, Utah, and southeast Pennsylvania; this is likely a consequence of high concentrations of C. botulinum spores in the soil of these regions

WOUND BOTULISM

● C. botulinum develops in grossly contaminated wounds

● 19 cases in 1995● Very common with black tar

heroine users/skin popping

blepharospasm and strabismus BOTOX

Therapeutic use of botulinum toxin

What is Blepharospasm?

Blepharo means "eyelid". Spasm means "uncontrolled muscle contraction".

The term blepharospasm can be applied to any abnormal blinking or eyelid tic or twitch resulting from any cause, ranging from dry eyes to Tourette's syndrome to tardive dyskinesia.

What is Strabismus?

Strabismus, also known as crossed or turned eye, is the medical term used when the two eyes are not straight. It occurs in approximately 2% to 4% of the population.

GAS GANGRENE

GAS GANGRENE● Tissue necrosis (death) from lack

of blood supply● Caused by C. perfringens● Neglected wounds (anaerobic

conditions) provide a suitable environment for C. perfringens growth

Clostridium perfringens

Gas gangrene

GAS GANGRENE (cont.)

● Highly lethal if untreated● C. perfringens ferments muscle proteins

and carbohydrates producing H2 and CO2

● Predisposing factors:

● Dirt in wound● Long delay before wound care● Induced abortion

GAS GANGRENE (cont.)

● Predisposing factors:● Arteriosclerosis● Diabetes

Gas gangrenein arm

Bone fracture withgas in surroundingmuscular tissue

Gas gangrenein foot

Gas gangrenein foot

Gas gangrene in buttocks

TREATMENT

● Removal of necrotized (dead) tissue● Amputation

● Hyperbaric O2

● Antibiotics

Hyperbaric chamber forgas gangrene treatment

Anthrax

Anthrax● Caused by Bacillus anthracis (aerobic;G+;

endospore former)● commonly found in the soil (South and

Central America, Southern and Eastern Europe, Asia, Africa, Caribbean and the Middle East)

● primary disease of domesticated and wild animals-particularly herbivores

● humans become infected when they come into contact with diseased animals (flesh, bones, hides, hair and excrement)

● Robert Koch-1876, 1877 isolated and obtained a pure culture

● Louis Pasteur-1881, developed a vaccine

Robert Koch

● Koch was a doctor and he had a detailed knowledge of the human body – something that Pasteur, as a research scientist – lacked.

● He was also skilled in experiments, the result of his work in natural sciences

● Qualities that also proved to be important were his ability to work for long periods of time and his patience

● However, Koch was also difficult to work with and could not tolerate anyone telling him that his theories were wrong

Robert Koch

● In 1872, Koch became district medical officer for a rural area near Berlin. He started to experiment with microbes in a small laboratory he had built for himself in his surgery.

Anthrax vaccine--Pasteur

● In France at that time many cattle suffered from anthrax, a serious disease from which many of them died.

● after many experiments Pasteur succeeded in producing a weakened & harmless culture of anthrax bacteria

● He inoculated cattle & sheep with this giving them a mild form from which they recovered

● When these animals were introduced with others who had a severe form they remained unaffected. They were immune.

Gram Stain-Gram Positive

Robert Koch’s Photos

● Human cases of Anthrax are rare: 1/100,000 risk

● Three forms:● Cutaneous-Most common form

● acquired through a cut or abrasion of the skin, which comes into contact with spores from the soil or a contaminated animal

● Inhalation-● acquired by the inhalation of spore-

containing dust where animal hair or hides are handled

● Intestinal- (Speculated)● consumption of contaminated meat

● Cutaneous-Spores germinate, vegetative cells multiply and a lesion (black=necrotic tissue) develops at the site of infection● Extreme cases involve bacteria in the

bloodstream which can be fatal (25%)● Inhalation-Symptoms may resemble a common

cold, progressing to abrupt fever and chest pain. After several days, severe breathing problems and shock, resulting in death (hemorrhage)—leads to 100% death if left untreated

● Intestinal-Inflammation of the intestinal tract, nausea, loss of appetite, vomiting, severe diarrhea and death (25-60%)

Cutaneous Anthrax

Treatment:● Antibiotics● Effective if given within 24 hours, or before

the bacteria enter the bloodstream● Penicillin, Tetracyclines, fluoroquinolones

(Cipro)● Vaccine● protective antigen (composed of a fraction

of the toxin)● 95% protective

● *No evidence of person-to-person transmission

● Anthrax Toxin-Symptoms and disease is caused by a toxin● made up of a protease (protein-digesting

enzyme)● B. anthracis form endospores● Spores may survive in the soil, water and on

surfaces for many years● Destroyed by autoclaving, burning, or

chlorination

Biological Warfare● Any disease-causing organism that is used as a

weapon● Anthrax has particularly useful features to be

used as a weapon● Stable in the environment (endospores)● spores that can be inhaled● once spores are inhaled, vegetative cells

grow and produce lethal toxins