Reservoirs Of Microorganisma Flashcards
What is a reservoir?
one or more epidemiologically connected populations or environments in which the pathogen can be permanently maintained and from which infection is transmitted to the defined target population
Discuss the characteristics and epidemiology of Bacillus anthracis
Microbial characteristics: large, gram positive, aerobic, endospore-forming, non- motile, rods occurring in chains
Epidemiology: infrequent and sporadic in most industrial countries
Discuss pathogenicity of bacillus anthracis
Can present in one of three forms (depending on the route of infection ):
- cutaneous anthrax: 95% of cases worldwide, results from infection through skin lesions due to spores traveling through the skin via an opening like a cut
- Pulmonary anthrax results from inhalation of spores
- intestinal anthrax- results from ingestion of spores, usually in infected meat
Endemic in agricultural regions like Africa, asia and Middle East from animals like goats can transfer to humans
Discuss the mode of transmission for cutaneous anthrax
Cutaneous anthrax- infection of skin by contact with infected animal tissues or by contaminated hair, wool, hides or products made from them
Usually gets in skin via cut or Scrape
Most common on the head, neck and forearm of the patient and affects skin and tissue around infect site
Without treatment, 20% die, with treatment nearly everyone lives. The least dangerous form of anthrax
Discuss the mode of transmission of ingestinal anthrax
Ingestinal anthrax- ingestion of contaminated undercooked meat
Discuss the mode of transmission of inhalation of anthrax
Inhalation anthrax- inhalation of spores in contaminated soil areas, dried or processed skins and hides of infected animals
Give the microbial characteristics of Bacillis Cereus
Microbial characteristics: large, gram-positive, aerobic, endospore forming, moitile rod
-produces heat stable and heat labile toxins
Usually results in food poisoning when cooked food is left open and spores germinate and produce toxins
Give the mode of transmission of Bacillus cereus
Ubiquitous organism of the soil
- commonly found in low levels in raw, dried and processed foods
- ingestion of foods kept at ambient conditions after cooking
Give the epidemiology of Bacillus cereus
Worldwide
Discuss pathogenicity of bacillus cereus
Opportunistic pathogen-
Immunocompromised individuals are susceptible
Intoxication characterized by two forms:
- An emetic form with severe nausea and vomiting
- A diarrhea form with abdominal cramps and diahrrea
Give the differential of clostridium and bacillus
Clostridium- obligate anaerobes
Bacillus- facultative aerobes
What are the microbial characteristics of Clostridium perfringens ?
Microbial characteristics: gram-positive , spore forming , non-motile, rods
-obligate anaerobes
What is the mode of transmission of clostridium perfringens?
- Primarily by the ingestion of food contaminated by soil or feces
- Spore transmission into the body via a break in the skin
Give the epidemiology of clostridium perfringens
Widespread and relatively frequent in countries with cooking practices that favor the multiplication of Clostridia
Give the pathogenicity of clostridium of Clostridium perfringens
Pathogenicity:
-food poisoning- intestinal disorder characterized by sudden onset of colic followed by diahrrea, nausea, but vomiting and fever is usually absent; mild, short in during, rarely fatal
-Wound contamination- traumatic or nontraumatic myonecrosis (gas gangrene ) and is specific to muscle tissue as it enters skin with little air, can grow rapidly between 43 and 47 degrees Celsius ; intra-abdominal sepsis, gangrenous cholecystitis
Usually develops hours or days after wound opens as tissues are devitalized which provide the anaerobic conditions and pathogen spreads along tissue, possibly causing sepsis
What is the most common bacterial agent for gas gangrene?
Clostridium perfringes
What are the microbial characteristics of clostridium tetani?
Microbial characteristics:
- Gram-positive, motile, spore forming bacteria (terminal spores with drumstick appearance)
- obligate anaerobes
- catalase and superoxide dismutase negative
What is the mode of transmission of clostridium tetani?
Contamination of wounds with soil or foreign bodies carrying C. Tetani spores
Tend to colonize small wounds, and release tetanus toxins which blocks release of neurotransmitters, glycine, gaba etc, chasing rigid paralysis
The epidemiology of clostridium tetani
Low in developed countries as a result of vaccination
However, For the first time in 30 years a young boy presented with the symptoms of clostridium tetani in Oregon
Discuss the pathogenicity of Clostridium tetanus
- Characterized by spastic paralysis.
- Contamination of a wound with C. Tetani
- the anaerobic tissue environment facilitates C. Tetani replication and secretion of exotoxins
What are the microbial characteristics of clostridium botulinum ?
Gram-positive, spore forming bacillus
- obligate anaerobes
- Seven types of C. Botulinum toxins(A-G)
What are the most potent toxins?
Most potent- clostridium botulinum
Second most potent- clostridium tetanus
What is the mode of transmission of clostridium botulinum ?
- food borne botulism: ingestion of contaminated food containing toxin
- Wound botulism: rare. Occurs when the spores get into an open wound and reproduce in an anaerobic environment
Wgive the epidemiology of clostridium botulism
Sporadic
Differentiate clostridium botulism and tetani paralysis
Botulism toxin interferes with choline release, causing flaccid muscle, descending paralysis where tetanus causes spastic paralysis
Explain the pathogenicity of clostridium botulinum
Characterized by descending flaccid paralysis
Causes diseases 3 ways:
Adult botulism- by the ingestion of the performed toxin in the food
Infant botulism- the intestinal colonization with Clostridium botulinum spores (occurs when infant is between 2-6 months)
Wound botulinum- the organism replicates in the wound and secretes toxin
What is another name for cpccidioides sp. ?
Valley fever, San Joaquin Vlley fever, or desert rheumatism
What are the microbial characteristics of coccioides sp.?
Microbial characteristics:
- Caused by Coccidioides fungus Coccidioides immitis and Coccidioides posadasii
- Both species of Coccidioides or dimorohic fungi that grow saprophytically as hyphae
What is the mode of transmission of Coccidioides sp. ?
Inhalation of spores. Very infectious as only one spore can cause disease
What is the mode of transmission of the Coccidioides sp. Coccidioidomycosis
Inhalation of spores. Very infectious as only 1 spore can cause disease
What is the epidemiology of coccidiodomyces ?
Southwestern United States and parts of Mexico and central and South America
Young women tend to be more affected- having painful subcutaneous nodules
Discuss the pathogenicity of coccidiodomycosis
Pathogenicity:
- fever, dry cough, flu like symptoms
- Airborne spores are inhaled by humans or many other species of mammals, infection develops in the lungs
Spores germinate in the soil and dust storms blow them far away, even to other countries
What are the microbial characteristics of legionella pneumonella?
Gram negative, strictly aerobic bacterium of the legionellaceae family
What is the mode of transmission of legionella pneumophilia?
The bacterium gets into the lungs.
Transmitted by aerosols(one breathes in contaminated water droplets ) or accidentally sucks (aspirates) contaminated water into the lungs
Becomes health concern when spread in human building water systems, hot tubs, supermarket etc
What is the epidemiology of legionella pneumophilia?
World wide prevelance
Occurs naturally in freshwater environments (e.g. lakes and streams) however it grows and spreads in human-made building water systems
Discuss the pathogenicity of legionella pneumophilia
- legionella can cause a serious type of pneumonia called legionnaires disease
- the bacteria can also cause a less serious illness called Pontiac fever
- Symptoms of legionnaire’s disease include confusion, headache, diarrhea, abdominal pain, fever, chills, and myalgia as well as a non-productive cough
Mortality rate- 15%-25%
What are the microbial characteristics of vibrio vulnificus ?
- Gram-negative, motile, curved rod-shaped, halophilic vibrio
- differential test- it is the only vibrio which ferments lactose
- Vibrio naturally live in brackish or salt water
What is the mode of transmission of Vibrio vulnificus ?
-Acquired from exposure to seawater through an existing open wound or through eating raw sea food
What is the epidemiology of Vibrio vulnificus?
Anyone can be affected by V. vulnificus-associated necrotizing fasciitis
What is the pathogenicity of vibrio vulnificus ?
Can cause two types of illnesses:
- Wound infections: which may start as redness and swelling at the site of the wound that can spread to affect much of the body
- Primary septicemia, a bloodstream infection with symptoms including fever, dangerously low blood pressure, and blistering skin lesions
What are the microbial characteristics of Vibrio parahaemolyticus ?
- Gram negative, halophilic, non-spore forming, oxidase-positive, facultative anaerobe, non-lactose fermenter, curved rod-shaped bacterium
- Has a polar flagellum, and a lateral flagella
What is the mode of transmission of vibrio parahaemolyticus?
- primarily through the ingestion of raw undercooked seafood( oysters, clams, and mussels)
- Wound infection by contaminated seawater or fish can cause infections and septicaemia
- can ferment glucose for gas production
Give the epidemiology of vibrio parahaemolyticus
Worldwide-vibrio naturally live in brackish or saltwater
Describe the pathogenicity/toxicity of vibrio parahaemolyticus
Three major clinical syndromes:
- 60-80% of infections cause gastroenteritis. Often caused by ingested sea food
- 34% wound infections, coming in contact with brackish water with a break in skin
- 5% septicemia
Give the microbial characteristics of vibrio cholerae
- gram negative, highly motile curved rods with a single polar flagellum
- Non lactose fermenter
- Over 200 known serogroups, differentiated by their O antigen
- only two serogroups, O1 and O139, are responsible for all epidemic and endemic cholera
What is the mode of transmission of vibrio cholerae?
Ingestion of water or food prepared with water containing V. Cholerae
Describe the epidemiology of Vibrio Cholerae
- Annually, 1.3 million to 40 million cases of cholera, and 21,000 and 143,000 cholera deaths worldwide
- Vibrio naturally live in brackish or salt water
- Cholera bacterium is also found in water or food sources that have been contaminated by feces from a person infected with cholera
Describe the pathogenicity of Vibrio cholerae
- Profuse watery diarrhea, vomiting, and leg cramps
- rapid loss of body fluids to dehydration and shock
- Without treatment, death can occur within hours
Describe the microbial characteristics of Naegleria fowleri
- A eukaryotic, free living amoeba belonging to the phylum percolozoa
- Thermophilic, free-living amoebas, trophozoites are 8-20 um in diameter and produce broadly rounded lobopodia
- Cysts are single-walled, spherical, flagellate is pear-shaped and motile, can revert to the tropic stage
Explain the mode of transmission of Naegleria fowleri
Naegleria fowleri invades brain and meninges via nose/nasal mucousa; infection by inhalation of cysts
Give the epidemiology of Naegleria fowleri
Worldwide in soil and warm fresh water (e.g. lakes, rivers, and hot springs)
Describe the pathogenicity of Naegleria fowleri
- Primary amebic meningoencephalitis (PAM), a rare, rapidly fatal disease with sudden onset of headache, fever stiff neck, lethargy, and coma in otherwise healthy people, detiorates brain tissue
- Amoebas splashed or inhaled onto the olfactory epithelium migrate up the olfactory nerve to the brain and spread via the subarachnoid space
You cannot get infected from drinking water contaminated with N. Fowleri
