comprehensive mixed deck - jonathan Flashcards
Let’s chat about botulism toxin… Is it resistant to heat? Is it resistant to stomach acid? How many types of toxins #? Which are the most common? How many subunits?
Heat labile Resistant to stomach acid 7 types of toxin (A to G) with A, B, and E being the most common two subunits to each toxin
T/F Neiseria are pathogenic in the mouth.
Neiseria have non-pathogenic and pathogenic strains which need to be distinguished for proper Tx N. meningitis can cause meningitis and can colonize the throat or the nasopharynx
What are normal flora of the skin?
Staphylococcus epidermidis S. aureus Diphtheroids (non-diphtheriae Corynebacteria) Anaerobes, such as proprionibacterium and peptococcus reside in the dermis. Also: proprionibacterium acnes
In what tissues do each reside? S. aureus S. epidermidis S. saprophyticus
What staph reside… Skin and nares Skin and mucus membranes Skin and GI tract
What are symptoms of S. saprophyticus UTI?
UTI with poluria and dysuria
Describe the Lancefield classification of streptococci.
Carbos extracted from the bacteria are subjected to precipitation tests with antisera. This places the beta-hemolytic groups into A through O. Note: group D is not beta-hemolytic
Explain the differences between Glomerulonephritis and Rheumatic Fever… Major symptoms? M-protein serotypes? Site of infection? Pathogenic mechanism?
1) G: edema, hypertension, hematuria. R: carditis, polyarthritis, subcutaneous nodules, skin lesions (erythema marginatum) 2) G: only a few types of M-protein. R: selected types of M-proteins but infection varies markedly by type 3) G: throat or skin, SKIN is more common. R: ONLY THROAT 4) G: deposition of immune complexes. R: antigenic mimicry between S. pyogenes and host tissue (heart, skin, and joints)
What is the pathogenesis and course of infection of infective endocarditis from Viridans Streptococci?
Alpha-hemolytic streptococci can infect through the mouth via oral trauma (including chewing) Causes transient bacteremia Bacteria can then bind to pre-existing lesion on heart valve Vegetation on valve Then has subacute course with intermittent bacteremia. Possibly fatal
What are the risks of a pregnant woman becoming infected with Listeria monocytogenes? Early term? Late term? Who is susceptible?
Bacteremia and transplacental infection Early term: abortion and still birth Late term: live births with risk of neonatal septicemia and meningitis Patients with cell-mediated immunosuppression are at risk
What can bacterial overgrowth in the small intestines cause?
Fat malabsorption B12 Deficiency bacteria belong in the large intestine, not the small intestine
When can bacteria grow in the upper small intestine?
Anatomical alterations (gastric bypass) can cause stasis and bacterial growth
What are Dx techniques do LABORATORIES use for Streptococcus?
1) G + chains 2) beta-hemolysis on blood agar 3) Sensitivity to Bacitracin indicates group A 4) Titer of >160 or a four-fold increase of Streptolysin O (ASO titer)
Bacteriology for Listeria monocytogenes… Gram status? Morphology? Hemolytic status? Motile? Temperature for growth?
G+ Rod Beta-hemolytic Motile with tumbling movement Grows well at cold temperatures, and creates risk for food contamination
Quick word on Wound-associated botulism… How is infection caused? What is Dx?
Spores in soil contaminate wound, germinate, and produce toxin Dx by wound culture or toxin in serum
Bonus question: Why… Metronidazole? Vancomycin? Fidaxomicin?
Metronidazole: anaerobic Vancomycin: G + multi-resistant enterococcus Fidoxomicin: a drug that stays in the intestines (doesn’t absorb into the blood) and is great for C. diff
What illnesses does Eikenella corrodens cause?
faculative gram - rod Skin and soft tissue infections associated with human bites and clenched-fist injuries (Like they said in kindergarden: No biting! My girlfriend does not listen to this)
Of the ALPHA GAMMA hemolytic, which strep is OPTOCHIN sensitive vs resistant?
alpha gamma optochin SENSITIVE S. pneumococci alpha gamma optochin RESISTANT Viridans streptococci
Compare Strep Pneumoniae with Viridians Strep in terms of Optochin Bile solubility
Strep pneumoniae is optochin SENSITIVE and bile SOLUBLE Viridians Strep is optochin RESISTANT and bile INSOLUBLE
Epidemiology for Anthrax (Bacillus anthracis)… Transmission?
Usually animal to animal. Humans are an accidental host.
Cutaneous anthrax… How does infection occur? What is its distinctive symptom? How serious is it?
Contamination of skin lesions by spores The lesion now produces a BLACK SCAB May lead to bacteremia The most common and least serious anthrax
How is differential Dx performed between botulism and Guilain-Barre syndrom?
Both are ascending paralysis illnesses that can be distinguished by patient history and laboratory toxin detection (serum, vomit, feces)
What are the byproducts of fast growing Clostridium perfringens?
H2 and CO2 gas
What is the Quelling reaction?
The Quellung reaction is a biochemical reaction in which antibodies bind to the bacterial capsule of Streptococcus pneumoniae, Klebsiella pneumoniae, Neisseria meningitidis, Haemophilus influenzae, and Salmonella. The antibody reaction allows these species to be visualized under a microscope. If the reaction is positive, the capsule becomes opaque and appears to enlarge.
Streptococcus Pneumoniae Gram status? Morphology? O2 status? Catalase? Oxidase? Optochin status? Bile solubility? Hemolytic status?
G + diplococci Faculative Anaerobe Catalase - Oxidase - Optochin SENSITIVE Bile SOLUBLE Alpha-hemolytic
What is the common clinical symptom caused by C. difficile?
antibiotic-associated diarrhea
What is the natural environment of Clostridium perfrinngens?
soil human GI vagina
Recap: What are the names of the anaerobic gram negative rods? Which is RESISTANT to penicillin?
Bacteroides fragilis Prevotella melaninogenicus Fusobacterium species B. fragilis is RESISTANT
What are the major and minor illnesses caused by Clostridium perfringens? What is the hallmark of infection?
1) GAS GANGRENE (histotoxinc clostridia) 2) food poisoning Hallmark: TISSUE NECROSIS Note: many species of Clostridium can cause gas gangrene. Clostridium perfringens is the most common. Gas production Gangrene from closed off blood vessels.
What is the prognosis of C. tetani infection?
60% fatality rate due to pulmonary complications and secondary infections This is why we get vaccinated
How is botulism prevented?
Cook all canned foods at 100 Celsius for 10 minutes
How is S. aureus strains determined during outbreaks? Doubtful we need to know the details
Serology Phage sensitivity/Phage typing DNA fingerprinting Ribotyping (rRNA) DNA of Protein A and Coagulase
What is the single most common bacteria in the stool? When can this cause injury?
Bacteroides fragilis Trauma or bowel rupture can cause intraabdominal infection produces anaerobic infection: foul smelling, gas producing, and necrotic
What are the gram stain, shape, and penicillin sensitivity of… 1) Fusobacterium 2) Prevotella 3) Anaerobic streptococci aka peptostreptococcus 4) Actinomyces
1) Cigar-shaped gram - rod, penicillin sensitive 2) gram - rod, penicillin sensitive 3) gram + cocci in chains, penicillin sensitive 4) Gram + branching rods, doesn’t say
Recap and Preview: What are the names of the anaerobic gram negative rods (3)? What are the names of the anaerobic gram positive rods (4)? What are the names of the anaerobic gram negative cocci (1)? What are the names of the anaerobic gram positive cocci (1)?
Anaerobic Gram - Rods: Bacteroides fragilis, Prevotella melaninogenicus, Fusobacterium species Anaerobic Gram + Rods: Corynebacterium, Lactobacillus, Actinomyces, Clostridia Anaerobic Gram - Cocci: Veillonella (quick note: commensal, not a pathogen) Anaerobic Gram + Cocci: Peptostreptococcus
What cultures should not be submitted for anaerobes?
Oral or fecal
what obligate anaerobes are found in intraabdominal abscesses (4)?
Bacteroides fragilis (resistant to penicillin) Fusobacterium Clostridium Peptostreptococcus
What is the mouth heart connection via Viridans streptococci?
Predominant microorganism in the mouth and are the most common cause of subacute endocarditis Note: they also make tooth plaque and hasten dental carries with lactic acid sugar fermentation
On growth mediums containing intact RBCs, explain the difference between… Gamma hemolysis Alpha hemolysis Beta hemolysis
1) no hemolysis 2) a cloudy green zone (RBCs are intact but the heme is green) 3) a clear zone with lysed RBCs Note: depending on the depth of hemolysis in the petri dish, the clear zone may not look completely clear
What is laboratory Dx for pneumococcal pneumonia?
Microscopic examination and culture of sputum Blood culture CSF culture
Aside from Clostridia botulism, what other bacteria is a common exotoxin food-borne diarrheal bacterial disease?
Staphylococcus aureus
Are food-poisoning enterotoxins secreted by S. aureus heat stable? To what temperature?
Heat stable. Resists boiling.
Explain how Gas Gangrene development is dependent on location.
Myositis is in muscle Fascitis is in fascia Cellulitis is is dermis and skin
What other illnesses must be considered in the differential Dx of botulism?
Myasthenia gravis (assymetrical) Guillain-Barre syndrome (assymetrical)
Explain the function of toxin A and B in C. difficile.
A binds to gut receptor B is cytotoxin that damages colonic mucosa and causes diarrhea (sometimes bloody) (B is a ADP-ribosylating Rho GTP binding protein
Epidemiology for Listeria monocytogenes… Where is it found? What foods are implicted?
Soil, water, and infected animals Dairy and meat
What obligate anaerobes are found in the Upper Respiratory Tract (4)? (oral or facial abscesses, sinusitis) (can spread to brain)
Prevotella Fusobacterium Peptostreptococcus Actinomyces (due to trauma)
What are the clinical syndromes of Streptococcus pneumoniae? What are the symptoms? Bacteremic? Fatal?
Pneumococcal pneumonia is the most frequent form of bacterial pneumonia Cough, fever, chills, pleuritic pain, RUSTY SPUTUM, leukocytosis 15% bacteremic 15% fatal if hospitalized Other syndromes include meningitis, otitis media, and sinusitis
What is Tx for Bacillus anthracis?
Ciprofloxacin Tetracycline Penicillin
Describe Fusobacterium species with regard to… Microscopic shape as a rod? Penicillin sensitive or resistant? Oxygen sensitive or resistant? Common sites of infections?
has tapered ends and are thinner than normal Gram - rods Penicillin SENSITIVE Oxygen SENSITIVE Oral infections, lung abscesses, pleuropulminary infections Note: some species are in GI infections, but says we don’t need to know these
What is lecithinase?
An alpha toxin that damages host cell membrane inclusing capillary and host erythrocytes
What is the pathogenesis of S. aureus as a toxin-mediating bacteria.
bacterial colonization (food, tampons, vasculature, skin) and production of the toxin. Toxin can affect areas anywhere in the body, not just at the site of colonization
With regard to morphology, how do you distinguish between 1) Streptococci Group A through O 2) Streptococcus pneumoniae (pneumococcus) 3) Neisseria (gonorrhea and meningiditis)
1) Chains of G+ 2) Diplococci with short dimension apposed 3) Diplococci with long dimension apposed
Page Q-11 is a quick review of the following as they relate to Colon health 2) Bifidobacterium 3) Lactobacili 4) Clostridia 5) Coliforms (E. coli) and Enterococcus 6) More than 400 other anaerobes 7) small amounts of aerobes, such as S. aureus, Pseudomonas, Proteus, Klebsiella
.
Explain the pathogenesis of Rheumatic Fever. On what tissue was the initial infection? How long after initial infection? What protein is involved? What tissues are involved?
Throat only. 2-3 weeks after strep infection M-PROTEINS activate antigens that attack SKIN, JOINTS, AND HEART Skin and joint problems subside. Heart problems may be ongoing
State invasive status and basic illness of the following: Clostridium botulism Clostridium tetani Clostridium difficile Clostridium perifringens Costridium septicum (don’t need to know) Clostridium ramosum (don’t need to know)
Clostridium botulism: noninvasive and causes botulism Clostridium tetani: generally noninvasive and causes tetanus (small invasive potential) Clostridium defficile: noninvasive and causes pseudomembranous enterocolitis Clostridium perifringens: very invasive and causes gangrene Costridium septicum: invasive in malignancy Clostridium ramosum: implies invasive in notes. Does not say.
Who is at highest risk for pneumococcal pneumonia?
Compromized HUMORAL immunity Spleenectomized patients pt with sickle cell anemia
What is the establishment of normal intestinal flora in newborns
Fetal intestine is sterile Breast fed babies have bifidobacterium Bottle fed babies have flora that resembles adults (they also are commonly overweight and have health troubles later in life)
What is impetigo?
Minor superficial skin infection of streptococcus
Normal flora in the genitorurinary tract?
Vagina: lactobacili Sometimes E. coli and Enterobacter is in the VJay 15-20% of women in childbearing age have Group B Streptococci in the Vjay. This can lead to sepsis in newborns.
What are five ANAEROBES that are common in the oral cavity?
1) Fusobacterium 2) Prevotella 3) Anaerobic streptococci aka peptostreptococcus 4) Actinomyces 5) others, such as anaerobic spirochetes
Yada Yada What are the clinical syndromes of food poisoning by S. aureus?
Nausea, vomiting, non-bloody diarrhea Note: these are specifically caused by the T-cell superantigen.
Corynebacterium… (this seemed deemphasized in the notes) What tissue does it normally inhabit? What test does it normally contaminate? What is it commonly called? Not a common infection, but there is one exception, which is?
Skin Contaminates blood samples Anaerobic diphtheroid Endocarditis in compromised patients
Which Staph is resistant to novobiocin?
S. saprophyticus
What is the pathogenesis of Clostridium perfringens with regard to food poisoning… (these seem like unecessary details) How many spores are required? Where is the enterotoxin found on the bacteria? What food is usually infected?
Needs lots of bacteria to cause infection (10^8) Enterotoxin is associated with the spore coat and the toxin is released into the intestine Usually found in meat
What are the clinical symptoms of botolulism toxin… Main symptom? Fever? Mental status? Sensory system? Affects on pharynx? Affects on eyes? Respiration?
Flaccid paralysis with bilateral symmetry in peripheral and cranial nerves No fever Normal mental status No sensory deficit Dysphagia and dry throat Diplopia (double vision) and diluted pupils May affect respiratory muscles
What is the gram stain and shape of Fusobacterium species?
Gram - rod
What is an EMG used for with botulism? Are the results conclusive?
electromyography tests diminished action potential of the peripheral nerves results are suggestive, not conclusive
What is the pathogenesis of Clostridium difficile?
Antibiotic-induced suppression of normal flora >> C. diff proliferates and produces two distinct toxins: exotoxin A and B
In Dx for Streptococcus, sensitivity to Bacitracin indicates what group?
Group A
page Q-3 has a chart of common anaerobic infection sites and their corresponding bacteria. It is not to be memorized.
page Q-3 has a chart of common anaerobic infection sites and their corresponding bacteria. It is not to be memorized.
What is Tx for Staphylococcus epidermidis?
1) remove implant 2) Vancomycin 3) possible combo with Rifampin and/or Gentamicin Interesting. Infection seems more mild, but we whip out the big guns for antibiotics.
What bacteria is the major cause of hospital bacteremias?
Staphylococcus aureus and Staph Epidermis
The use of antibiotics can cause what bacteria to overgrow?
Commonly, Salmonella and Shigella Also C. diff
What do you need to know about the bacteriology of S. epidermidis? Gram stain and other distinctive features…
Coagulase negative (S. epidermidis and S. saprophyticus only) Gram + Staphylococci with white colonies Catalase + (distinguishes staph from strep) Sensitive to NOVOBIOCIN
Quickly, what keeps the intestines in healthy flora?
Low oxygen Low pH Commensal bacteria produce synergistic products, such as vit K Commensal bacteria produce antibiotics that target harmful bacteria
What Dx techniques do physicians use?
A bead test that demonstrates linkage by strep chains pharyngeal swab is used
Intestinal anthrax… What food source? How common?
Ingestion of spores from meat. Rare.
Under what conditions do bacteria grow in the stomach?
Immediately after meals In the case of illness, such as Gastric Achlorhydia or Gastric Obstruction
Due to the severity of C. tetanus, there is a prophylaxis protocol if a person has a possibly infected wound. Wounds are either… 1) less than 6 hours old, clean, non-penetrating with neglible tissue damage 2) other wounds In each circumstance, what prophylactic Tx is required for… A) Pt with vaccine within 5 years? B) Pt with vaccine between 5 and 10 years? C) Pt with vaccine more than 10 years? D) Pt with unknown vaccine status?
A) 1 and 2: no Tx required B) 1 and 2: give one vaccine of inactivated toxiod C) 1: give one vaccine of inactivated toxiod. 2: one vaccine plus human tetanus Ig D) 1: three course vaccine. 2: three course vaccine plus human tetanus Ig Slide 30 has flow chart.
What faculative anaerobe is found in the dental area (1)?
Streptococcus viridans
What symptoms do the following toxins cause… 1) Botulism toxin? 2) Tetanus toxin? 3) Exotoxin A and B (Clostridium difficile)? 4) Alpha toxin (Clostridium perfringens)?
1) flaccid paralysis 2) tetanus (locked jaw) 3) diarrhea in pseudomembranous colitis 4) lecithinase which hosts cell membrane in combination with other degradative enzymes as the cause for “Gas Gangrene”
Of the non-spore forming anaerobes, what are the gram negative rods (name 4)?
Bacteroides (lower GI and female genital tracts. Abdominal infections) Fusobacterium (mixed infections. Oral and/or GI infections) Prevotella (oral infections) Poryphyromonas (oral and peridontal infections)
What is necrotizing fascitis?
“Flesh-eating bacteria disease” Invasive S. pyogenes Rapid infection Surgery may be required
What are the clinical symptoms of Clostridium perfringens food poisoning?
Abdominal cramps watery diarrhea for 8-22 hours resolves within 24 hours note: this is the 2nd or 3rd common cause of food poisoning
Detail: What is the recent emergent virulent strain?
27
fyi: Carbs not absorbed in the small intestine, feed the bacteria in the large intestine and keep the pH low
fyi: Carbs not absorbed in the small intestine, feed the bacteria in the large intestine and keep the pH low
What does botulism toxin do to nerves?
blocks acetylcholine release from nerve at neuromuscular junction details: the toxin is a protease that degrades the Ach vessicle docking proteins
Note: only 10% of bacteremias are caused by anaerobes. Which two anaerobes cause the most bacteremias?
Bacteroides fragilis Clostridium perfringens
What are the clincal syndromes of S. aureus S. epidermidis S. saprophyticus
1) toxin-mediated disease (food poisoning, TSS, and SSSS) and Invasive syndromes 2) Invasive syndrome commonly associated with foreign bodies 3) UTIs in young females attaches to uroepithelium via hemagluttanin
Streptococcus pneumoniae pathogenesis… Where are these bacteria resident? What causes infection? How does the bacteria deal with IgA? What is its lytic compound?
Resident in the oropharynx If aspirated plus cilia or phagocytosis is compromised, pneumonia can develop Protease to IgA Pnuemolysin
Explain how Bacteroides produce ammonia.
The metabolic activity of theses bacteria generates ammonia, acid, and gas in the colon. Ammonia is formed by splitting urea and from proteins.
Which have resistance to NOVOBIOCIN? S. aureus S. epidermidis S. saprophyticus
sensitive sensitive RESISTANT
Pathogenesis… Is C. botulism invasive? What tissue is ultimately affected? How does the toxin travel to that tissue?
C. botulism is not invasive. Affects nerves: flaccid paralysis (flaccid descending paralysis. Starts with the head and goes down. If hits respiratory muscles, you’re dead.) The botulism toxin is absorbed in the intestine, carried through blood to nerves. The toxin binds to a receptor on the nerve an is taken up by the nerve.
What is Erysipelas?
Severe cellulitis of the dermis and underlying tissues by streptococcus
What are the lysogenic toxins and enzymes that are produced by Clostridium perfringens?
Lecithinase: an alpha toxin that damages host cell membrane (including capillary and host erythrocytes) Collagenase: degrades ECM Hyaluronidase: degrades ECM
What pharyngeal and respiratory complications can occur with C. tetani?
respiratory failure possible aspiration, dysphagia, and oral pharyngeal involvement complications may be pulmonary infections and respiratory problems
Detail: What strain of S. aureus contain exfoliatins A and B?
phage group I
T/F Staph aureus is pathogenic because it is an INVASIVE disease, rather than an exotoxin producing bacteria.
False. S. aureus produces toxin-mediated diseases and invasive diseases.
What color are the colonies for S. aureus, S. epidermis, and S. saprophyticus?
S. aureus is yellow S. epidermis and S. saprophyticus is white
What neurotransmitters does tetanus toxin affect?
inhibits the release of glycine and GABA resulting in spastic paralysis and convulsive contractions aka locked jaw
What faculative anaerobes or aerobes are found in OB/GYN?
E. coli Klebsiella Proteus Streptococcus group B Staphylococcus
Knowledge of local flora aids in Dx and Tx. For example: Compare oral infections vs intraabdominal infections in their gram stain, shape, and penicillin senstitivity vs resistance
Oral infections: Gram + cocci and Gram - rods, penicillin senstitive Intraabdominal infections: Gram - rods, penicillin resistant
What are M proteins in streptococci?
M-proteins extend from the bacterial membrane through the capsule and into the extracellular membrane They aid in adhesion and antiphagocytosis They are antigenic and are a possible target for the immune system
Are acapsular streptococci pathogenic?
No
What is Px for S. aureus S. epidermidis S. saprophyticus
1) Handwashing and isolation 2) Handwashing 3) Not listed
What is the Tx for C. diff?
Stop offending antibiotics (usually ampicillin, cephalosporins, or clindamycin Treat with Metronidazole, Vancomycin, or Fidaxomicin Fecal transplantation
What is the gram status and linking of Group A Strep. pyogenes Group B Strep. agalactiae Group D Enterococcus Viridans Streptococci S. pneumoniae aka pnuemococci
All G+ in chains, except S. pneumoniae pnuemococci is LANCET shaped DIPLOCOCCI
Inhalation anthrax… How does infection occur? What demographic is most at risk of exposure? What are the steps of infection? How serious is it?
Inhalation of spores In undeveloped nations, people who work with wool and animal hides Spores >> phagocytized by macrophages >> germinate in lymph nodes >> medialstinal lymph enlargement Rapidly fatal
What obligate anaerobes cause bacteremia (4)?
Bacteroides fragilis Clostridium Fusobacterium Peptostreptococcus
What is the gram stain and shape of… Viridans streptococci Neisseria species Diphtheroids aka Corynebacterium species not including C. diphtheriae Staphylococci epidermidis Eikenella corrodens
Viridans streptococci: Gram + cocci Neisseria species: Gram - diplococci Diphtheroids aka Corynebacterium species: Gram + rods pleomorhic Staphylococci epidermidis: Gram + cocci in grape like clusters Eikenella corrodens: faculative Gram - rod
What are SpeA, SpeB, and SpeC? What are the two illnesses that they cause?
Protease pyrogenic exotoxins SCARLET FEVER (origin oropharyngeal streptococci) STREPTOCOCCAL TOXIC SHOCK SYNDROME
Viridans Streptococci… What type of hemolysis? What are the most common species? What tissues do they normally inhabit?
Alpha hemolysis Streptococcus mutans and Streptococcus sanguis mouth, nose, and pharynx
What are the subunits of the tetanus toxin? What do each do?
Subunits A and B B subunit binds to neuronal ganglioside A subunit has neurotoxin activity