Flashcards in Anaerobic bacteria Deck (54):
C tetani are what? How can it be introduced?
environmental, gram positive, and spore-forming; Think soil contamination of wounds like splinters, IV drugs, septic surgery, thorns
C tetani releases what? What are the four types of disease?
Neonatal tetanus involves
contamination of umbilical cord and lack of materal immunization
Cephalic and local tetanus
both have low mortality so long as they remain local
In generalized tetanus, what happens to the exotoxin? What can lead to >50% untreated mortality?
It ENTERS THE BLOODSTREAM;
In C tetani, the two subunits are
B and A, with B delivering A to end of motor neuron and A moves retrograde to CNS
The A subunit acts as what?
a protease, cleaving synaptobrevin in inhibitory motor nerves of the CNS
On C tetani exam, what are some hallmark features? Test that can demonstrate C tetani?
1. Local rigidity, difficulty swallowing
2. Strong muscle spasms/paralysis
3. Trismus (lockjaw)
4. Grimace (risus sardonicus)
5. Look for the STRONG ARCHING OF THE BACK!;
Spatula test: they bite down
Lab tests for C tetani include:
1. Microscopy with tennis racket appearance
2. Bloodwork can confirm vaccination and rule out STRYCHNINE POISONING
For C tetani treatment, this includes
tetanus antitoxin to neutralize the toxin;
could use antibiotics like metronidazole, but wound often clear on presentation;
Prevention of C tetani includes
vaccination, with tetanus toxoid, while adults get boosters every 10 years; unvaccinated adults can get vaccine at any time
C botulinum is a; presents as; most common sources of C botulinum?
gram +, spore-forming, environmental bacteria; foodborne botulism;
alkaline vegetables like home-canned beans or if the spores survive inadequate sterilization of pre-prepped foods
C bot: Germinating cells infected by ____ phage release what?
lysogenic; botulinum toxins, with A and B being most common
For C botulinum, what happens to germinating bacteria and the bot exotoxin? How do bot and tetani differ once they arrive at a neuromuscular junction?
The germinating bacteria typically die;
bot tetani will stay in periphery and affect ACh release!!
A consequence of Bot pathogenesis is
flaccid paralysis and could affect respiratory system
Two less common presentations of Bot include
Infant botulism (kid is floppy and has uncooked honey) and wound botulism (wound contaminated in IV drug user)
On exam for bot, you would see in foodborne botulism
descending weakness and paralysis, and patient has history of suspect foods
For treatment of C botulinum what are you worried about? What is needed in wound botulism?
Horse-sourced antitoxin can inactivate toxin in bloodstream, which could lead to SERUM SICKNESS;
debride and high-dose IV penicillin
How to prevent C botulinum?
Cook adequately, sterilize the canned foods and vacuum-packed foods, and discard swollen cans!!
What can botulinum toxin A be useful for?
Cosmetics and blepharospasm (eyelid), writer's cramp, anal fissures and torticollis
C perfigrens is a
gram pos spore-forming rod that can lead to necrotizing fasciitis/myonecrosis
How does C perfringens enter? What can be seen on histology?
Serious wounds like war, car accident, septic abortion, where you disrupt blood flow;
C perfrigens can produce
alpha toxin with enzymes that break down tissue
On exam, C perfringens can show
1. Bronze skin color, then blue-black
2. maybe develops at site of malignancy
3. could see crepitation and tachy
4. Then ARDS, renal failure, shock!!
In C perfringens, what do you see on radiography, and what is needed to confirm myonecrosis?
Feathering pattern of gas in soft tissue;
SURGICAL EXPLORATION FIRST!!
To treat C perfrigens and prevent it?
Can give antibiotics like penicillin G and clindamycin, or clindamycin with metronidazole;
clean and debride the wounds!!
In C perfringens, besides gas gangrene, what can happen?
Food poisoning: inadqueate cooking fails to kill the bacteria and the spores grow up
For C perfringens poisoning, what area is affected?
Type A enterotoxin can destroy tight junctions between epi cells in gut
Tests, treatment and prevention for C perfringens food poisoning?
None required; DON'T STOP THE DIARRHEA;
C difficile is a ____ that causes what? How can it emerge?
Gram positive, spore-forming rod; pseudomembranous colitis;
fecal-oral or can come up in normal gut flora and spike in hospitalized pop (maybe antibiotic use)
What two toxins of C diff can cause issues?
Exotoxin A: disrupts tight junctions and causes intestinal swelling and inflammation
Exotoxin B: MAJOR TOXIN, disrupting cytoskeleton by depolymerizing acting, killing surrounding cells
On C diff exam, what could be seen?
Nonbloody cramping diarrhea; antibiotic use, chemo, or immunsuppressants in history;
patches of dead cells on sigmoidoscopy, maybe toxic megaolon or colonic perforation
Treatment of C diff?
1. Withdraw initial antibiotics
2. Unless disease is very mild, give oral metronidazole or vanco
3. LET TOXINS FLUSH
4. Maybe removal/surgical resection of colon
Bacteroides and prevotella are
gram-negative bacilli that are NON-SPORE forming; these guys are opportunistic pathogens that are in normal flora of mucous membranes
Treatment of B and P complicated by
1. slow growth (potential antibiotic resistance)
2. polymicrobial, so if one secretes beta-lactamase, whole abscess/colony protected from penicillin!!
Abscesses for B and P start off as ___ which use up the O2, followed by?
Facultative anaerobes; anaerobes
Diagnosis of B and P includes in the history:
Painful abscess that could move to meningitis (neck)
B and P are usually found
below the diaphragm if B, above if P
B and P can be diagnozed lab-wise via
needle aspiration (bypass normal flora and maintain anaerobic condition); MAKE SURE YOU CULTURE ON ANAEROBIC BLOOD AGAR; identify by sugar fermentation and gas chromatograpohy
Treatment and prevention of B and P includes
metronidazole primarily, and combine with aminoglycides to kills facultatives in abcesses, REQUIRES SURGICAL CARE;
gram+ filmaentous rods, non spore-forming; anaerobitc to microaerophilic and normal flora of mouth, vag
Actinomyces pathology includes
bacteria escaping proper compartment during trauma; non-comm, with good prognosis
Presentations of actinomyces include:
1. Head/neck: pus drainage and hard, non-tender swelling in face, neck, chest; history of dental work, poor dental hygiene
2. Abdomen: slow-growing tumor and usually diagnozed on EXPLORATORY SURGERY
For actinomyces: you'll see on lab; treatment could include
branching Gram+ rods with sulfur granules; can be anaerobically cultured;
penicillin G with possible surgical drainage
SS: Anaerobic infections usually follow
deep-tissue trauma: accidents, cancer, surgery, immunosuppression, IV drug use
SS: For what is there a vaccine available?
SS: All of the anaerobes here are? What is gram pos and neg?
Clostridia and actinomyces are gram pos, B and P are gram neg
SS: of the bacteria in this lecture, which are environmental, normal flora, both?
Environmental: C tetani, botulinum;
normal: C difficile, B and P, and actinomyces;
Both: C perfringens
SS: C tetani and botulinum produce
neurotoxins with same protease activity butopposite clinical effects because of nerves affected: tetanospasmin inhibitor CNS leads to spasms, botulinum toxin stimulatory on periphery, leading to flaccid paralysis
SS: Diagnosis of C tetani and botulinum includes; infection is usually; how do you treat? who is affected?
exam; the infection is usually transiet; treatment is primarily with ANTITOXIN to bind and inactivate neurotoxin; you would see this in neonates, IV drug users, infected wounds, botulism in contaminated food
SS: C perfringes in gas gangrene, B and P produce; how do you identify and treat? What's special about gas gangrene?
identify by anaerobic culture and gas chromatography, treat with antibiotics plus surgical care; resolved ASAP: lethal exotoxemia
SS: C perfringens in food poisoning produces
enterotoxin: symptomatic treatment
SS: C difficile causes ____ after what? How to treat?
pseudomembranous colitis; antibiotic use;
often nosocomial, change antibiotic and intervene SURGICALLY as necessary