Week 16 - Bacte Flashcards
attaches to the neuromuscular junction of nerves and prevents the release of acetylcholine.
Botulinum toxin
What are the clinical uses of Botulinum toxin type A (botox)?
Botulinum toxin type A is used to treat strabismus and as a beauty enhancer by improving frown lines temporarily.
What is the causative agent of Tetanus?
Clostridium tetani is the causative agent of Tetanus.
acts on inhibitory neurons, preventing the release of neurotransmitters in Tetanus
Tetanospasmin
What are the clinical manifestations of Tetanus?
Tetanus results in a spastic type of paralysis, with continuous muscular spasms leading to trismus (lockjaw), risus sardonicus (distorted grin), and difficulty breathing
How does Tetanus occur?
Tetanus occurs when spores in the environment enter the skin through puncture wounds.
What is the incubation period of Tetanus?
The incubation period of Tetanus has been reported to range from 3 to 21 days.
What is the prevention measure for Tetanus?
The prevention measure for Tetanus is the diphtheria tetanus-acellular pertussis (DTaP) vaccine.
What causes myonecrosis or gas gangrene?
Organisms like C. perfringens, C. histolyticum, C. septicum, C. novyi, and C. bifermentans contaminate wounds, leading to myonecrosis or gas gangren
What is the effect of gas gangrene exotoxins (; ×Fðxin)?
Gas gangrene exotoxins cause necrosis of the tissue and allow deeper penetration by the organisms.
What clinical manifestations is this include pain and swelling, bullae (fluid-filled blisters), serous discharge, discoloration, and tissue necrosis.
Clinical manifestations of gas gangrene
What is the most common cause of antibiotic-associated diarrhea and pseudomembranous colitis?
Clostridium difficile.
What toxins are produced by C. difficile?
C. difficile produces two toxins: toxin A (enterotoxin) and toxin B (cytotoxin).
presents with bloody diarrhea and associated necrosis of the colonic mucosa.
Pseudomembranous colitis
What is actinomycosis characterized by?
Actinomycosis is characterized by the development of sinus tracts and fistulae that erupt to the surface and drain pus containing sulfur granules.
Where are many cases of actinomycosis commonly seen?
Many cases of actinomycosis can be seen in the maxillary region, but the common site is the female genital tract associated with the use of long-standing intrauterine devices (IUDs).
Which bacteria is the most common cause of actinomycosis?
Actinomyces israelii is the most common cause of actinomycosis.
What causes Bacterial Vaginosis (BV)?
BV is caused by a shift in the vaginal biota resulting in the overgrowth of endogenous anaerobes such as Mobiluncus spp., Bacteroides spp., Prevotella spp., anaerobic gram-positive cocci, and Gardnerella vaginalis.
What are the clinical features of Bacterial Vaginosis (BV)?
Clinical features of BV include gray-white, homogenous, malodorous vaginal discharge, with little or no discomfort and no inflammation.
What does an overgrowth of lactobacilli in the vagina result in?
An overgrowth of lactobacilli in the vagina results in the production of lactic acid, which lowers the vaginal pH and suppresses the overgrowth of other organisms.
Which lactobacillus species is the most common in the healthy vagina?
The Lactobacillus acidophilus complex constitutes most of the lactobacilli of the healthy vagina.
What serious infections can occur with lactobacilli in immunocompromised patients?
Immunocompromised patients can experience serious infections like bacteremia and endocarditis caused by lactobacilli.
What opportunistic infections are caused by lactobacilli in patients receiving vancomycin?
Patients who received vancomycin can experience opportunistic infections like endocarditis and polymicrobial abscesses caused by lactobacilli.
What genera of anaerobic Gram-Negative Bacilli are commonly encountered?
The genera commonly encountered include the B. fragilis group, Porphyromonas, Prevotella, and Fusobacterium.
What types of infections are anaerobic Gram-Negative Bacilli often associated with?
Anaerobic Gram-Negative Bacilli are often associated with peritoneal infections following disruption of the gastrointestinal (GI) lining.
Where can anaerobic bacteria be found?
They can be found in soil, freshwater and saltwater sediments, and as components of the endogenous microbiota of humans and other animals.
What are exogenous anaerobes?
Anaerobes that exist outside the bodies of animals.
Give an example of exogenous anaerobes.
Genus Clostridium
What are endogenous anaerobes?
Anaerobes that exist inside the bodies of animals (endogenous microbiota), the source of endogenous infections.
What are the anaerobes commonly involved in human infections?
Actinomyces spp., Bacteroides spp., Prevotella spp., Porphyromonas spp., Fusobacterium spp., Clostridium spp., peptostreptococci
Which anaerobe causes actinomycosis?
A. Israelii, other Actinomyces spp.
Which anaerobes are responsible for antibiotic-associated diarrhea?
Clostridium difficile
Which anaerobes are associated with brain abscess?
Bacteroides spp., Prevotella spp., Porphyromonas spp., Fusobacterium spp., Clostridium spp.
Which anaerobes are involved in infections of the female genitourinary tract?
Peptostreptococci, Bacteroides spp., Clostridium spp., Prevotella bivia, P. disiens, Actinomyces israelii
What are the anaerobes responsible for intraabdominal infections, liver abscess, peritonitis, and perineal infections?
Bacteroides fragilis group, other Bacteroides spp., Fusobacterium spp., Clostridium spp., peptostreptococci
Which anaerobes cause myonecrosis?
Clostridium perfringens, C. novyi, C. septicum
Which anaerobes are associated with oral, sinus, and dental infections?
Peptostreptococci, Porphyromonas spp., Fusobacterium spp.
Which anaerobes are responsible for aspiration pneumonia and pleuropulmonary infections?
Porphyromonas spp., F. nucleatum, peptostreptococci, B. fragilis group, Actinomyces spp.
Which anaerobe is commonly found on the skin?
Propionibacterium acnes
What can cause contamination in blood cultures?
Contamination from the patient’s skin resulting from poor site preparation during the venipuncture.
What anaerobic bacilli are present in the respiratory tract?
Prevotella, Porphyromonas, Fusobacterium, and other anaerobic cocci
Where do anaerobes outnumber facultative anaerobes?
In the gastrointestinal tract, by a factor of 1000:1.
Which anaerobe accounts for less than 1% of the human intestinal biota?
Bacteroides fragilis
Which anaerobes are commonly isolated from human feces?
B. vulgatus, B. thetaiotaomicron, B. distasonis, Bifidobacterium, Clostridium, Eubacterium, and the anaerobic gram-positive cocci
What percentage of bacteria in cervical and vaginal secretions are anaerobes?
50%
Name some anaerobes found in the genitourinary tract.
Anaerobic cocci, Fusobacterium, Prevotella, Bacteroides, and Lactobacillus
Why are GU swabs and voided or catheterized urine specimens unacceptable for anaerobic bacteriology?
They may contain facultative anaerobes or aerobes that overgrow the anaerobes.
What are some examples of gram-positive, spore-forming anaerobic bacilli?
Clostridium spp.
How do Clostridium toxins access the body?
Usually through ingestion or open wounds contaminated with soil.
What infections can Clostridium cause?
Wound or abscess infections, and it can be isolated from the blood in cases of bacteremia.
What types of food poisoning are associated with Clostridium perfringens?
Type A (mild and self-limited GI illness) and type C (more serious but rarely seen disease)
What causes type A food poisoning caused by C. perfringens?
It is caused by a C. perfringens enterotoxin linked to sporulation.
What causes type C food poisoning associated with C. perfringens?
- It is associated with strains that produce B-toxin and, less commonly, ; a-toxin.
How many antigenically different botulinum toxins are there?
- only types A, B, and E are associated with human disease.
What are the clinical manifestations of person to person contact with infected lesions?
Papules, nodules, ulcers
What is the primary lesion of treponema pallidum subsp. pallidum?
Mother yaw - a sore that is most often painless but causes itching
What does treponema pallidum subsp. endemicum cause?
Endemic Nonvenereal Syphilis
How is treponema pallidum subsp. endemicum transmitted?
Person to person contact (mouth to mouth by utensils)
What are the clinical manifestations of treponema pallidum subsp. endemicum?
Skin/mucous membrane patches - papules, macules, ulcers and scars
What does treponema carateum cause?
PINTA
How is treponema carateum transmitted?
Person to person contact (through infected lesions)
What are the clinical manifestations of treponema carateum?
Hyperkeratotic pigmentation may lead to disseminated skin lesions and lymphadenopathy
What are the laboratory diagnosis specimens for treponema?
Ulcers or lesions, tissue, needle aspirate, umbilical cord
How can treponemes be identified in lesions?
Dark-field microscopy, direct fluorescent antibody - T. pallidum (DFA-TP), PCR
What are the nontreponemal tests for serologic diagnosis?
Rapid Plasma Reagin (RPR), Venereal Disease Research Laboratory (VDRL)
What are the treponemal tests for serologic diagnosis?
T. pallidum particle agglutination (TP-PA) test, Fluorescent treponemal antibody absorption (FTA-ABS) test, Particle gel immunoassay (PaGIA), T. pallidum indirect hemagglutination (TPHA)
Why is susceptibility testing not performed for treponemes?
Because treponemes cannot be cultivated
What is the drug of choice for therapy of treponemes?
Penicillin G
What alternative drugs can be used for treponema therapy when patients are allergic to penicillin?
Tetracycline or doxycycline
What is the highly effective alternative drug for early syphilis therapy?
Ceftriaxone
What is the scientific name for the organisms responsible for louseborne or epidemic relapsing fever?
Borrelia recurrentis
How is louseborne or epidemic relapsing fever transmitted?
Tick bite
What are the clinical findings of louseborne or epidemic relapsing fever?
Petechiae, fever, myalgia, diffuse abdominal tenderness, conjunctival effusion
How can Borrelia organisms be visualized in laboratory diagnosis?
Directly in wet preparations of peripheral blood, or staining thick and thin films with Wright stain or Giemsa stain
What is the most common vector-borne disease in North America and Europe?
Lyme disease caused by Borrelia burgdorferi
How is Lyme disease transmitted?
Bite from Ixodes ticks
What are the stages of Lyme disease?
First stage (Erythema migrans), Second stage, Third stage
What are the clinical characteristics of the first stage of Lyme disease?
Ring shaped skin lesion with a central clearing, fever, muscle and joint pain, malaise
What are the clinical characteristics of the second stage of Lyme disease?
Arthritis, neurologic disorders (i.e. meningitis), carditis
What are the clinical characteristics of the third stage of Lyme disease?
Chronic arthritis or acrodermatitis chronica atrophicans (ACA), and a diffuse skin rash
What are the specimen types used for laboratory diagnosis of Lyme disease?
Blood, biopsy specimens, body fluids (synovial fluid and CSF)
How can Borrelia burgdorferi be visualized in laboratory diagnosis of Lyme disease?
In Warthin-Starry silver stain
What medium is used for incubation of Borrelia burgdorferi in laboratory diagnosis
Modified Kelly’s medium incubated at 30°C to 34°C in a microaerophilic environment
What are the serologic tests used for Lyme disease diagnosis?
IFA, ELISA
What is the therapy for relapsing fever caused by Borrelia?
Tetracycline
What are the characteristics of leptospira organisms?
Spiral-shaped, right-handed helices
