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147 Cards in this Set
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Causes whooping cough
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Bordetella pertussis
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Bordetella: gram neg or pos?
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neg
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What are the 4 virulence factors of bordetella pertusis that cause attachment to the ciliated epithelial cells of the trachea and bronchi?
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1) Pertussis toxin
2) Extra cytoplasmic adenylate cyclase 3) Filamentous hemagglutinin (FHA) 4) Tracheal cytotoxin |
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What does the pertussis toxin do and how?
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B subunit Binds to target cell receptors allowing entry of A subunit (Active) which results in increase of cAMP. Causes histamine sensitization, increase in insulin synthesis, and promotion of lymphocyte production and inhibition of phagocytosis.
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What does the extra cytoplasmic adenylate cyclase do and how?
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Weakens host cells defense by weakening ability to phagocytose and clear bacteria.
Bordetella pertussis throws adenylate cyclase grenades that get swallowed by host defense cells. This results in impaired chemotaxis and generation of H202 and superoxide. |
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What does the Filamentous hemagglutinin (FHA) do and how?
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It's a pili rod that is involved in the binding to the ciliated epithelial cells of bronchi. Antibodies are directed against this.
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What does the Tracheal cytotoxin do and how?
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Destroys ciliated epithelial cells, resulting in impaired clearance of bacteria, mucus, and inflammatory exudate. Probably responsible for violent cough.
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Majority of whooping cough cases occur in what age group?
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infants <1 year
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What are the 3 stages of whooping cough, caused by bordetella pertussis?
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1) Catarrhal stage
2) Paroxysmal stage 3) Convalescent stage |
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Characteristics of the Catarrhal stage of whooping cough
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Lasts 1-2 weeks, similar to URT infection. Low grade fever, runny nose, sneezing. Most contagious here.
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Characteristics of the Paroxysmal stage of whooping cough
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Development of coughing bursts. Cough is nonproductive. Attacks consist of 5-20 forceful coughs followed by inspiratory gasp thru narrowed glottis, giving "whooping" sound. Can cause vomiting. Patient can become hypoxemic.
Can last a month or long. More severe in young. Cause of chronic cough in adults. |
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Characteristics of the Convalescent stage of whooping cough
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Attacks become less frequent over a month and patient is no longer contagious
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A frequent cause of chronic unexplained cough in young adults and adolescents.
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Bordetella pertussis (whooping cough)
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What will changes in WBCs be in whooping cough?
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Increase in lymphocyte count with modest increase in neutrophils (similar to a virus)
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How to culture Bordetella pertussis?
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It's fastidious. Specimens for culture are collected with a calcium alginate swab. Put on a special medium called Bordet-Gengou medium (potato, blood, glycerol agar). Can use ELISA or PCR assays.
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What tissues does Bordetella attach to?
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Ciliated cells of respiratory mucosa
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Treatment of Pertussis
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Supportive (can give steroids).
Erythromycin (early disease) lessens transmission but has little influence on the length or course of the infection |
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Vaccination for whooping cough includes what?
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DTaP vaccine.
Pertussis toxin, FHA, adenylate cyclase. Combined with inactivated tetanus and diphtheria toxoids. |
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Bacterium attacking lungs of persons debiliated by viral flu infection
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haemophilus influenzae
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Characteristics of haemophilus influenzae
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small, pleomorphic, gram-neg, aerobic or facultative anaerobic. May produce capsule but most dont have it Obligate human parasite transmitted via respiratory route
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What confers virulence to haemophilus influenzae?
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Polysaccharide capsule. (Highly virulent strains produce type B capsule).
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which is the most virulent capsule of haemophilus influenzae?
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Type B (b = bad)
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What patients are particularly susceptible to nontypeable (no capsule) H influenzae?
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COPD
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What diseases can type B strains cause?
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1) Meningitis: pediatric
2) Septic arthritis, epiglottitis - very serious, can kill by blocking airway. |
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T/F H influenzae is cause of flu
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F
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What does the Type B H influenzae capsule contain?
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polyribitol phosphate or PRP
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T/F polyribitol phosphate or PRP is highly antigenic
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T. This is what the vaccine contains
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Non-typeable Haemophilus influenzae: What diseases does it cause?
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Respiratory tract infections in COPD
Otitis media |
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Most serious infection caused by Haemophilus influenzae type B
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Meningitis in children
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What are the 3 bacteria responsible for most meningitis acquired by baby coming out of birth canal (within first 3 months)
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1) Listeria monocytogenes
2) E coli 3) Group B strep |
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What are the two bacteria causing meningitis after maternal antibodies wear off (6 months - 3 years)?
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Neisseria meningitides and Haemophilus influnzae
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Characteristics of the acute epiglottitis caused by H influenzae
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Rapid swelling that can kill (need tracheotomy). Stridor, excessive saliva. Large, red epiglottis looks like a red cherry.
If found, don't examine larynx unless ready to insert endotracheal tube because manipulation can cause laryngeal spasm, causing complete airway obstruction |
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In what population is septic arthrtis caused by H influenzae?
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Infants. results in fever, pain, swelling and decreased mobility of one joint
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How is HiB (haemophilus influenzae B) meningitis treated?
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Cefotaxime, ceftriaxone: preferred.
Chloramphenical is alternative. Prophylaxis is with rifampin for patients having contact with diseased. |
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T/F There is a HiB vaccine
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T
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Which type of HI causes Cellulitis –subcutaneous inflammation of connective tissue?
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NTHI strains
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How is H. influenza Diagnosed?
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Gram stain of CSF
Capsular Ag test by countercurrent electrophoresis Particle latex agglutination test Culture of CSF on chocolate agar |
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What adult populations should be vaccinated for H influenzae?
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HIV/AIDS
People treated long term with steroids Cancer patients Bone marrow or organ transplants Damaged or no spleen |
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Which Haemophilus strain can cause chancroid or soft chancre?
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Haemophilus ducreyi
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How can Haemophilus chancres be differentiated from syphilis chancres?
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They are painful. Syphilis chancres aren't painful.
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Difference between Haemophilus chancroids and herpes
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Larger in size
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Treatment of haemophilus chancroids
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Azithromycin
Ceftriaxone Alternatives Trimethoprim sulfamethoxazole erythromycin |
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What type of bacteria is Neisseria gonorrheae?
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Small, non-motile gram-negative cocci often arranged in pairs. Resemble N meningitidis
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N gonorrheae is oxidase (pos, neg)
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Pos. Produces acid from glucose and no other sugars
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Selective media are important for gonorrhea why?
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they contain several antimicrobials to inhibit the growth of normal flora. This is important to plate specimens collected from complicated niches like cervix, rectum, oropharynx
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What are virulence factors of Neisseria gonorrhoeae?
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1) Pili: can undergo complex gene rearrangement
2) Outer membrane protein porins 3) Opa proteins |
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What role do Pili play in virulence of Neisseria gonorrhoeae?
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They mediate initial attachment to mucosal epithelial cells. Composed of repeating subunits. There is phase variation and antigenic variation
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What role do Opacity proteins (Opa) play in virulence of Neisseria gonorrhoeae?
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Impart an opaque character to colonies, facilitate tight adherence and invasion into host cells. They're named as their expression results in opaque colonies.
Influences tissue tropism |
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What role do outer membrane protein porins (PorA and PorB) play in virulence of Neisseria gonorrhoeae?
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promote invasion into epithelial cells
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Two pathogenic Neisseria
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Neisseria meningitidis - epidemic, endemic
Neisseria gonorrhoeae - STD |
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T/F Both Neisseria meningitidis and gonorrhoeae can be commensal
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F. Gonorrhoeae is always considered a pathogen, not a commensal.
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T/F Neisseria have flagella
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F
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What does it mean that Neisseria is oxidase positive?
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Means they have aerobic metabolism (high levels of Cytochrome C oxidase)
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Initial adherence of Neisseria mediated by
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Pili - antigenically heterogenous
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The acid production of sugars is used in Neisseria to__________
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differentiate different species
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T/F Both Neisseria meningitidis and gonorrhoeae utilize glucose and maltose
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F. Only Meningitidis. Gonorrhoeae only uses glucose.
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in clinical specimens, especially CSF, Neisseria meningitidis (the meningococcus) is usually seen with what cells?
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PMNs/neutrophils
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What determines the serogroup of Neisseria meningitidis?
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Capsular polysaccharide
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How can the capsular polysaccharide increase virulence?
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By interfering with phagocytosis
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T/F Meningococcus can release blebs of LPS
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T.
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What causes the petechiae in meningococcal infections?
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release of LPS that causes blood vessel destruction
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In what organism is IgA1 protease (cleaves IgA) found?
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meningococcus
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How does neisseria meningitidis spread?
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respiratory secretions
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Classic clue to meningococcal infection
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petechial rash
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Symptoms of meningococcemia
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Petechial rash, spiking fevers, chills, joint pain, muscle pain. Patients look ill
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What is fulminant meningococcemia/Waterhouse-Fridrichsen syndrome?
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Septic shock. Bilateral hemorrhage into the adrenal glands occurs, causing adrenal insufficiency. Abrupt onset of hypotension and tachycardia occurs, along with rapidly enlarging petechial skin lesions. DIC and death can occur rapidly (6-8 hours)
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Most common form of meningococcal disease
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meningitis, usually in infants <1 year
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Lipooligosaccharide (LOS)
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Similar to LPS. Determines immunotype
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Translocates into host cell membranes
Effects on apoptosis Alters Ca influx - induces phagocytosis |
PorB
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Virulence factors of meningococcus?
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1) Capsule: antiphagocytic
2) Endotoxin (LOS) 3) IgA1 protease 4) Pili |
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The meningitis vaccine is against what?
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Haemophilis influenzae
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What is the most common cause of meningitis in adults?
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Neisseria meningitidis
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How do dx meningococcal disease?
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Gram stain and culture from blood, CSF, or petechial scrapings.
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Classic medium for culturing Neisseria
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Thayer-Martin VCN (chocolate agar with antibiotics that kill competing bacteria)
V: vancomycin. Kills gram positives. C: colistin/polymixin: kills all gram-negs except Neisseria N: nystatin: kills fungi |
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Treatment for neisseria meningitidis
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Penicillin G or ceftriaxone IMMEDIATELY. Close contacts treated with rifampin
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How differentiate neisseria meningitidis from gonorrheae in lab?
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N meningitidis able to produce acid from maltose metabolism, N gonorrheae CANNOT (N gonorrheae makes acid from glucose only)
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T/F Neisseria meningitidis is only cause of epidemic meningitis, leading cause of endemic meningitis
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T
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Causes meningitis in extremes of age (infants, elderly)
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Strep pneumoniae (pneumococcus)
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Causes meningtiis in neonates to 3 months
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Group B Strep (Strep agalactiae), Listeria, E coli
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Causes meningitis in infants to 5 years and young adults
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neisseria meningitidis
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Causes meningitis in children 6 months to 5 years, but much less common since Hib
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Haemophilus influenzae
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4 local infections caused by Neisseria meningitidis
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Pharyngitis - sore throat in presence of meningococcal carriage
Pneumonia - cough, chest pain, recent viral infx, often due to serogroup Y, low mortality Urethritis - purulent urethral discharge, usually seen in homosexual males Proctitis - similar to urethritis |
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Meningitis symptoms
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With or without meningococcemia
Rapid onset fever, severe headache, chills, stiff neck, altered mental status, cloudy CSF |
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Symptoms of meningococcemia (meningococcus in blood)
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Fever, coma, circulatory collapse (shock), hemorrhage onto skin, ARDS, bilateral destruction of adrenal glands
Waterhouse-Friderichsen syndrome |
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Chronic effects of meningococcal infection
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Arthritis-pericarditis syndrome-1-2 weeks after onset of meningococcal disease
Recurrent meningococcal infection-C’ deficiencies, systemic lupus Neurological sequelae (30% survivors): Deafness - Paralysis Retardation - Blindness |
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What to do with probable case of meningococcal disease?
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Positive detection test for antigen (latex agg.) or DNA (PCR)
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What do meningococcal vaccines NOT protect against?
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induce serogroup-specific antibodies (no protection against group B)
Group B not immunogenic; endemic strain |
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What to do with suspect case of meningococcal disease? (purpura fulminans or gram neg diplococci IDd by Gram stain)
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Begin treatment with presumptive identification
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What is tx for meningococal disease?
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Penicillin G; Dexamethosone (meningitis. Controversial); Also experimental therapies aimed at diminishing human immune response like anti-cytokine agents and rBPI
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Characteristics of neisseria gonorrheae
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Small, non-motile, Gram-negative diplococci
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When is it appropriate to use chocolate agar to dx gonorrhea?
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When using something that's normally sterile (blood). NOT from vagina or penis, etc.
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When is it appropriate to use Selective media - MTM, NYC to dx gonorrhea?
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Appropriate for plating samples from complicated niches (endocervix)
. They contain antibacterials |
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Virulence factors mediating initial attachment to mucosal epithelial cells; composed of repeating subunits called pilin; phase and antigenic variation occurs at high frequency
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Pili virulence factors
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T/F No capsular polysaccharides
in N. gonorrhea |
T
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What virulence factors:
Impart opaque character to colonies Allow cell-to-cell adherence Influences tissue tropism Subject to phase and antigenic variation |
Opa (opacity) proteins
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What virulence factor:
Elicits blocking antibodies - reduces serum bactericidal activity In close association with PorB and LOS |
Rmp: reduction modifiable protein
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How does Neisseria gonorrheae (aka gonococcus) avoid host defense?
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1) Phase variation - producing quantitative surface changes leading to immune evasion/tissue tropism
2) Antigenic variation: involving qualitative surface changes 3) molecular mimicry - looking like the host. |
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Symptoms of gonorrhea in men
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urethritis. Painful urination with purulent urethral discharge
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Tx of gonorrhea in men
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ceftriaxone
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Symptoms of gonorrhea in women
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Urethritis is more likely to be asymptomatic with minimal urethral discharge.
Cervix becomes reddened and friable with purulent exudate. Large %age are asymptomatic |
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PID is an infection of what?
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uterus (endometritis); fallopian tubes (salpingitis); ovaries (oophoritis)
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T/F Over 50% of PID cases occur within one week of menstruation onset
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t
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What is LOS?
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Lipid A and core oligosaccharide
Endotoxin, cytotoxic to fallopian tube epith. Antigenic variation basis for immunotyping |
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What is role of plasmid-mediated resistance in N gonorrheae?
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Penicillin-resistance plasmids - encode b-lactamase - PPNG; can be mobilized by a conjugative plasmid
Tetracycline-resistance - tetM protects ribosomes - TRNG; on a conjugative plasmid |
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What is role of chromosome-mediated resistance in N gonorrheae?
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penA - altered penicillin-binding protein 2
penB - reduced permeability of outer membrane to b-lactam antibiotics gyrA - DNA gyrase less sensitive to quinolone antibiotics - QRNG mtr - wild-type locus allows export of antibiotic agents: erythromycin, detergents |
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Other than the genitals, where else can gonorrhea infect?
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Anorectal infection
Pharyngeal infection Conjunctivitis |
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Symptoms of PID
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Lower abdominal pain following menses, pain on movement, fever, leukocytosis
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Complications of PID
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1) Infertility - scarring of fallopian tubes
2) Ectopic pregnancy 3) Abscesses 4) Peritonitis 5) Peri-hepatitis (Fitz-Hugh-Curtis syndrome) - infection of capsule surrounding liver |
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Fitz-Hugh-Curtis syndrome: what is it?
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Infection of capsule surrounding liver (peri-hepatitis)
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Most common kind of septic arthritis in young, sexually active individuals
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Gonococcal
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What is ophthalmia neonatorum and what causes it?
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Eye infection caused by gonorrhea from mother.
Can cause blindness if untreated Rare in US due to use of antimicrobial eye drops following vaginal birth |
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Symptoms of Disseminated gonococcal infection
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gonoccocemia.
Fever, joint pains, skin lesions. |
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Who usually gets disseminated gonoccocal infection?
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Women, usually in context of asymptomatic endocervical infection.
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How to dx gonorrhea?
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Remove pus from urethra by inserting thin sterile swab.
Gram stain and culture on Thayer-Martin VCN. Will see doughtnut-shaped diplococci within WBCs |
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What are gram-neg intracellular diplococci and significance of?
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Gonoccoci frequently seen within PMNS, used for direct microscopic exam of second swab specimen
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treatment for gonorrhea
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3rd gen cephalosporins.
Ceftriaxone. (usually give doxycline or azithromycin because of co Chlamydia infection) |
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How to distinguish gonorrheae from Acinetobacter?
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Acinetobacter is oxidase negative
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How to distinguish gonorrheae from Kingella?
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Kingella: oxidase positive coccoid bacilli; catalase neg
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How to distinguish gonorrheae from Moraxella?
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Moraxella doesn't produce acid upon fermentation of glucose
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Which Chlamydia responsible for Non-Gonococcal Urethritis, trachoma, LymphoGranuloma venereum)
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Chlamydia trachomatis
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Which Chlamydia responsible for atypical pneumonia?
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Chlamydophila pneumoniae
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Which Chlamydia responsible for psittacosis or parrot fever?
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Chlamydophila psittaci
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Where does Chlamydia live?
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It's an obligate intracellular parasite - can only live inside animals cells. Energy parasite
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Why was Chlamydia once considered a virus? Why is it a bacteria?
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small size and intracellular growth requirement.
Shares features with typical bacteria (ribosomes, rna and dna), LACKS typical peptidoglycan |
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What does Chlamydia not have that most bacteria do?
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a peptidoglycan (so no muramic acid)
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Chlamydia is especially fond of what areas?
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mucous membranes (conjunctivitis, cervicitis, pneumonia)
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What is MOMP?
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Major outer membrane protein. Major surface antigen, cross-linked by disulfide bonds
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What are the two morphologically distinct forms of chlamydia?
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Infectious elementary bodies (EB) and noninfectious reticulate bodies (RB)
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Characteristics of Infectious elementary bodies (EB) of chlamydia
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Induces own endocytosis, prevents phagolysosomal fusion and allows survival. Once inside endosome, EB reorganizes into reticulate body (RB)
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Characteristics of reticulate bodies (RB) of chlamydia
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noninfectious. Capable of binary fission.
After division, RB transforms back into EB and is released by cell via exocytosis. |
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Chlamydia lifecycle
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1) EB attaches to and enters via endocytosis columnar epithelial cells that line mucous membranes
2) Once within an endosome, EB inhibits phagosome-lysosome fusion and isn't destroyed. Transforms into initial/reticulate body (IB or RB) C) Once enough IBs have formed, some transform back into EB D) Host cell liberates ED which can infect more cells |
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Two organs that chlamydia trachomatis infects
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eyes, genitals
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What is trachoma?
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Chronic conjunctivitis caused by C. trachomatis leading cause of preventable blindness in world.
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What are the two biovars of C. trachomatis?
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Trachoma biovar (causes trachoma and chlamydia STI)
Lymphogranuloma venereum (LVG) biovar |
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Treatment for trachoma
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Oral azithromycin
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Trachoma caused by what serovars?
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A, B, C
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Chlamydia STD caused by what serovars?
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D-K
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Serotypes L1,L2,L3 cause what disease?
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Lymphogranuloma venereum (LVG)
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Adult and neonatal inclusion conjunctivitis caused by what?
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The STD. Usually spread from mother to child. Children in US given erythromycin eye drops
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Signs and symptoms of
Lymphogranuloma venereum (LVG) |
Another STD.
Primary lesion at site of infection but often overlooked because it heals rapidly which distinguishes it from syphilis and herpes. May include fever, headache, myalgia. Second stage includes inflammation and swelling of lymph nodes draining site of infection (inguinal). Enlargement of lymph nodes over next two months, may break open and drain pus. |
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Human infection from inhalation of bird feces - no person-to-person spread. Causes pneumonia.
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C. psittaci
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Symptoms of C. psittaci
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fever, chills, headache, cough
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occupational hazard for breeders of carrier pigeons, vets, and works in pet shops or poultry slaughterhouses
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Chlamydophila psittaci
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What type of disease of C. pneumoniae cause?
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Atypical (walking pneumonia), similar to that caused by M. pneumo, L. pneumo.
Also: pharyngitis, bronchitis, sinusitis; associated with atherosclerosis P-t-P transmission: respiratory droplets |
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Coughing man with clam necklace on, bird Psitting on his arm.
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C. psittaci. Caused by exposure to birds.
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What antibiotics used for C. pneumoniae?
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Tetracyline, erythromycin
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Why can't penicillin be used for Chlamydia?
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penicillin acts on the peptidoglycan synthesis, and chlamydia doesn't have peptidoglycan
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