Gram Positive Bacilli Flashcards
Lecture 7
Where is Listeria monocytogenes found?
in environment and causes stillbirths and meningitis in a wide range of animals
Who does Listeria monocytogenes effect?
in humans, we see infection in neonates, pregnancy, and the immunocompromised; we see it with epidemics associated with foodborne illness
How do we test for Listeria monocytogenes?
we can take a specimen, culture, or use molecular detection (such as PCR)
Where is Corynebacterium spp. found?
it is found in the environment and normal flora of humans and animals in skin, oral cavity, and genitourinary (GU) tract of humans
What are some characteristics of Listeria monocytogenes?
it is an opportunistic pathogen, most often considered contaminants when isolated, it is a gram-positive bacilli that resembles “L” or “V” shapes and may palisade (line up parallel)
What is Corynebacterium diphtheriae?
a pathogen that has an exotoxin when infected with a phage that carries the TOX genes - this toxin affects myocardium and peripheral nervous system: death is a result of asphyxiation or myocarditis
What disease can Corynebacterium diphtheriae cause?
Diphtheria; pharyngitis with a thick, leathery, gray membrane; fever and malaise
How do we test for Corynebacterium diphtheriae?
via specimen, and methods like serology, culture, molecular detection, and toxin production detection (ELEK test or PCR test)
How do we treat diphtheria?
diphtheria antitoxin, antibiotics, and supportive therapy
Where do we find Corynebacterium jeikeium?
is a part of our normal skin microbiome, and one of the most commonly encountered Corynebacterium in clinical specimens
What diseases does Corynebacterium jeikeium cause?
infection in immunocompromised, prosthetic heart valve infection, septicemia, skin infections
Where is Nocardia spp. found?
in the environment, it is NOT a part of our normal microbiome; it is also a strict aerobe
What does Nocardia look like?
long, slender, gram-positive bacilli that show branching and beading
What disease does Nocardia cause?
it is an opportunistic pathogen, it causes bronchopulmonary and cutaneous infections; if it spreads it goes to the central nervous system can causes brain abscesses
How do we test for Nocardia?
we take a culture from a specimen
What are some characteristics of Gardnerella vaginalis?
there is only 1 species; it is a facultative anaerobe; gram-stain shows gram-variable pleomorphic bacilli; fastidious
What disease does Gardnerella vaginalis cause?
bacterial vaginosis; it presents as green, frothy vaginal discharge with a foul odor, we can diagnosis by presence of clue cells
How can we test for Gardnerella vaginalis?
we take a specimen and use antigen detection, we can also use a wet prep slide to look for clue cells
What are some characteristics of Lactobacillus spp.?
it is a normal flora of the gastrointestinal and genital tracts; decrease in number with bacterial vaginosis; rarely causes disease
What are some general characteristics of the Bacillus species?
generally low virulence; found in soil, water, dust, and animal products; common contaminant in lab; produces SPORES; thee gram-stain is large, box-car shaped bacilli that may stain gram-variable, aerobe or facultative anaerobe
What is Bacillus anthracis?
the major pathogen of the Bacillus genus
What disease can Bacillus anthracis cause?
causes the infection called anthrax in grazing animals; most virulent human pathogen of the Bacillus species and is discussed as an agent used for biological warfare; causes anthrax in humans (pulmonary, cutaneous, and gastrointestinal)
What disease does Bacillus cereus cause?
causes food poisoning associated with rice dishes; eye and wound infections (less frequently)
How can we test for Bacillus cereus?
take a specimen and use molecular assays for B. anthracis, culture for both B. anthracis and B. cereus
What are some characteristics of Clostridium?
gram-stain is large gram-positive bacilli; anaerobes; produce spores
Where is Clostridium found?
it inhabits the soil, water, vegetation, large bowel of humans and other animals; many are significant pathogens of livestock and wildlife
What are the characteristics of Clostridium perfringens?
it produces many exotoxins and enzymes that divide the organism into 7 types (A-G), with type A being most important to humans; large-box-car shape gram-positive bacilli; growth is rapid; produces high amounts of gas
What disease does Clostridium perfringens cause?
gas gangrene, invasion of muscle around a wound site by Clostridium that caused necrosis and gas is produced when the muscle carbohydrates are fermented by the organisms; food poisoning
How do we test for Clostridium perfringens?
collect specimen and culture
What are the characteristics of Clostridium difficile?
present in bowel of healthy persons or acquired from an exogenous source; antibiotic therapy alters the normal microbiome of the bowl and allows C. difficile to overgrow
What disease does Clostridium difficile cause?
produces toxins; bloody diarrhea is a result and may develop a pseudomembrane - pseudomembranous colitis
How do we test for Clostridium difficile?
take specimen and use molecular detection, culture with reflex to cytotoxin assay, antigen detection, or immunosorbent assay (ELISA) for C. diff toxin and or C. diff organism
How can we identify C. diff without needing to test?
colonies smell like horse manure; in a culture the colonies have a “ground glass” apperance
What is the potential treatment?
we may be able to use stool transplant to treat it
What are characteristics of Clostridium tetani?
spores enter the body through wounds; then germinate to vegetative cells; in soil, dust, human and animal excrement; produces toxin is conditions right and travels to CNS
What disease does Clostridium tentani cause?
tetanus - blocks muscle relaxation muscles contract at the same time; diagnosis is clinical
How do we treat tetanus?
1) neutralize circulating toxin with antitoxin
2) relieve muscle spasms
3) keep airways open
4) remove infected tissue and treat with penicillin
5) tetanus toxoid booster shot
Where is Clostridium botulinum found?
spores are in soil, water, and on surface of fresh vegetables
What diseases does Clostridium botulinum cause?
food botulism - associated with inadequate processing of canned foods, toxin is inactivated by sufficient cooking (100 C for 10 min.); wound botulism; infant - organism introduced into baby’s system in honey and other dietary supplements; botulism causes muscles to not contact making the persons flaccid
How can we test for Clostridium botulinum?
usually performed by public health departments
How can we treat Clostridium botulinum?
penicillin and high dose horse antitoxin; supprotive measures
