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Infectious Disease > Other gram negatives > Flashcards

Other gram negatives Flashcards

1
Q

Moraxella catarrhalis

A
  • gram neg diplococci
  • colonized airways
  • can cause otitis media, COPD exacerbations
  • Usually treated empirically without microdiagnosis
  • not in most lab algorithms
    • non-virulent strains of Neisseria comon airway flora
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2
Q

Neisseria sp

A

N gonorrhea

N meningitidis

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3
Q

how to tell which Neisseria

A
  • Both ferment glucose but
  • Meningococcus ferments maltose
  • gonococcus ferments only glucose
  • Both produce IgA protease
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4
Q

Neisseria treatment

A

Ceftriaxone used to treat gonorrhea and menigitides

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5
Q

Neisseria meningitidis

A
  • causes meningitis and meningococcemia
  • transmitted by respiratory droplets
  • Enters pharyx then blood stream then CSF
  • Many asymptomatic carriers
  • virulent strains have polysaccharde capsule that prevents phagocytosis
  • Lipooligosaccharide outer membrane (LOS) acts just like LPS on enteric gram neg rods
  • Vaccine available
    • contains capsular polysaccharides -> anti-capsule anti-bodies
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6
Q

Meningococcemia

A
  • bacteremia that can complicate N meningitis
  • sepsis
  • fevers
  • chills
  • tachycardia
  • purpuric rash
  • DIC
  • Waterhouse-Friderichsen syndrome
    • adrenal dysfunction from meningococcemia
  • Life-threatening!
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7
Q

Neisseria meningitidis treatment

A
  • Spread via droplets so take droplet precautions (mask)
  • Prophylaxis:
    • Rifampin
    • Also Ceftriaxone or ciprofloxacin
      *
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8
Q

Complement pathway deficiency

A

Nesseria meningitidis

C5-C9 deficiency

recurrent Nm infections

most often meningitis

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9
Q

N gonorrhea illnesses

A
  • mainly causes gonorrhea
  • can also cause
    • PID
    • septic arthritis
    • Neonatal conjunctivitis
    • Fitz-Hugh-Curtis syndrome
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10
Q

N gonorrhea key virulence feature

A
  • antigenic variation of pilus proteins resulting in no long-term immunity after infection
  • Re-infection likely
  • No vaccine
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11
Q

Gonorrhea

A
  • most men/women with gonorrrhea are asymptomatic
  • N. gonorrhea and Chlamydia often co-infect
    • both can cause similar symptoms
    • treat for both (Ceftriaxone, Azithromycin/Doxycycline)
  • Men
    • Dysuria, discharge
    • epididymitis/orchitis
  • Women
    • itching, purulent discharge from cervix
    • not painful
    • can progress to PID
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12
Q

Pelvic inflammatory disease

A
  • gonorrhea infection ascends to uterus, ducts and ovaries
  • pelvic/abdominal pain
  • Dyspareunia
  • Cervical motion tenderness on exam (chandelier sign)
  • High risk of subsequent ectopic pregnancy, infertility
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13
Q

Fitz-hugh-curtis

A

Gonorrhea

  • perihepatitis
  • inflammation of Glisson’s capsule around liver
  • Severe RUQ tenderness with pleurtic pain
  • Violin string adhesions of parietal peritoneum to liver
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14
Q

Septic arthritis

A
  • gonorrhea
  • disseminated gonococcal infection (0.5-3%)
  • key scenario
    • sexually active young person
    • swollen, warm and painful knee
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15
Q

Neonatal conjunctivitis AKA

A

Ophthalmia neonatorum

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16
Q

Neonatal conjunctivitis

A
  • caused by Gonorrhea or chlamydia
  • swelling and discharge from the eye
  • 5 to 14 days after birth
  • untreated can lead to visual impairment
  • prophylaxis: erythromycin ophthalmic ointment
  • new born prophylaxis mandated by many states
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17
Q

Chlamydia features

A
  • obligate intracellular organisms
  • cannot make their own ATP
  • cell wall lacks muramic acid
    • N-acetylmuramic acid (NAM) in peptidoglycan
    • cell wall lacks peptidoglycan
  • does not gram stain well but are technically gram negative
  • Giemsa stain
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18
Q

Chlamydia treatment

A
  • Penicillins do not work
  • Ceftriaxone (for gonorrhea) ineffective
  • Azithromycin or Doxycycline (protein synthesis inhibitors)
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19
Q

Chlamydia life-cycle

A

2 phases

  1. Elementary body (small, dense)
    • enters cell via endocytosis
  2. Reticulate body
    • replicates in cells by fission
    • can be seen in tissue culture
  • Elementary bodies and reticular bodies grow, multiply and eventually rupture the cell and disperse
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20
Q

Types of Chlamydia bacteria

A
  • C. trachomatis (sexually-transmitted)
  • C. pneumonia (atypical pneumonia)
  • C. psittaci (Parrot fever)
21
Q

Chlamydia trachomatis illnesses

A
  • Nongonococcal urethritis
  • PID
  • Conjunctivitis
  • Reactive arthritis
22
Q

Chlamydiophila pneumonia illnesses

A
  • Atypical pneumonia
  • Transmitted by aerosol
23
Q

Chlamydiaphila Psittaci illnesses

A
  • Psittacosis (Parrot fever)
  • infection from birds
24
Q

Nongonococcal urethritis

A
  • Caused by Chlamydia trachomatis
  • sexually transmitted
  • Often asymptomatic in men & women
  • women
    • cervicitis
      • clear discharge, post-coital bleeding
      • can progress to PID, Fitz-Hugh-Curtis
  • Men
    • dicharge
    • dysuria
25
Q

Nongonococcal urethritis treatment

A
  • want to treat for chlamydia and gonorrhea
    • Chlamydia
      • Azithromycin/doxycycline
    • Gonorrhea
      • Ceftriaxone
26
Q

Newborn chlamydial infection

A
  • infection from passage through the birth canal
  • conjunctivitis
    • similar to gonorrhea
  • Pneumonia
    • 4-12 weeks old
    • classic feature is “Staccato cough”
    • Inspiration between each single cough
    • often have history of conjunctivitis
27
Q

C. trachomatis diagnosis

A
  • Nucleic Acid Amplification Test (NAAT)
    • PCR of chlamydia DNA/RNA
    • Gold standard
  • Culture and staining
    • no longer routinely done
    • Giemsa stain
    • Chlamydial inclusion bodies in cytoplasm of epithelial cells
28
Q

Reactive arthritis

A
  • Autoimmune arthritis
  • triggered by infection (Chlamydia, but also intestinal infections (salmonella, Shigella, Campylobacter, Yersinia, C. difficile))
  • Classic triad (Reiter’s Syndrome)
    • arthritis (often unilateral, lower extremities, knees, toes)
    • Conjunctivitis (red eye, discharge)
    • Urethritis (dysuria, frequency-noninfectious)
  • Diagnosis
    • classic features following typical infection
  • Treatment
    • NSAIDs
29
Q

Lymphogranuloma venereum

A
  • Chlamydia infection that enters the lymphatics (different serotypes from those that cause urethritis)
  • sexually transmitted
  • Initially: genital ulcer (sometimes unnoticed, resolves)
  • Later: Tender inguinal or femoral lymph nodes
  • Treatment:
    • Drainage
    • Abx (azithromycin/doxycycline)
30
Q

Trachoma

A
  • Caused by Chlamydia trachomatis (unique serotypes)
  • Mostly in Africa and other developing parts of the world
  • Highly contagious
  • spread by contact with eye secretions
  • acutely causes conjunctivitis
  • Repeated infections -> corneal scarring -> blindness
  • Leading cause of infectious blindness worldwide
31
Q

Chlamydia serotypes A, B, C

A
  • Trachoma, blindness Africa
32
Q

Chlamydia serotypes D - K

A
  • Urethritis
  • PID
  • neonatal pneumonia
  • neonatal conjunctivitis
33
Q

Chlamydia serotypes L1, L2, L3

A

Lymphogranuloma venereum

34
Q

Campylobacter sps

A
  • C jejuni
  • C. coli
35
Q

Campylobacter features

A
  • faint gram negative spiral, curved rod (comma shaped)
  • oxidase positive
  • Microaerophilic
    • requires oxygen but lives best with low O2 levels
36
Q

Campylobacter illnesses

A
  • very common cause of acute diarrhea in children
  • a leading cause of acute diarrhea worldwide
  • Fecal-oral transmission
    • lives in animal intestines, especially poultry
    • undercooked meat especially poultry
    • unpasteurized milk
    • can also contaminate drinking water
  • common trigger of Guillain-Barre
    • demyelinating disease
    • Ascending weakness
37
Q

Vibrio cholera features

A
  • toxin-mediated disease
  • toxin carried by bacteriophage (lysogenic)
  • permanently activates Gs -> increase cAMP
  • Voluminous “rice-water” diarrhea
  • requires large dose of bacteria for infection
    • stomach acid kills bugs
    • common in areas that lack clean water
    • also can occur on acid suppression drugs (lower req’d dose)
  • death from dehydration, electrolyte losses, shock
  • Treatment: aggressive volume repletion
38
Q

Vibrio vulnificus/parahaemolyticus

A
  • Both cause food poisoning (diarrhea)
  • raw oysters
  • V. vulnificus can infect wounds after swimming in contaminated water
39
Q

Haemophilus influenza

A
  • Gneg colonizes nasopharynx
  • causes several respiratory diseases, meningitis
  • some have polysaccharide capsule and some dont
    • capsular are typeable into 6 serotypes (a to f)
    • others are nontypeable
  • Most disease is caused by serotype B
    • capsule consists of ribosyl and ribitol phosphate polymer
  • Vaccine contains type B capsule (Hib)
    • conjugated to a carrier protein (often tetanus toxoid)
    • stronger T-cell response
    • given before 7 months
40
Q

Haemophilus influenza special features

A
  • Produces IgA protease
  • Grows on chocolate agar
    • Factors V (NAD) and X (hematin) present
    • will also grow with Staph aureus on blood agar
41
Q

Haemophilus influenza illnesses

A
  • Epiglottitis in children
  • Pneumonia
  • Meningitis
  • Otitis media
  • Bronchitis
  • Conjunctivitis
42
Q

Epiglottitis

A
  • life-threatening illness caused by H. flu (airway obstruction
  • unvaccinated children with fever and sore throat
  • Dysphagia, drooling
  • epiglottis will appear “cherry red”
43
Q

H. influenzae vaccine doesn’t protect against

A
  • more commonly caused by strep pneumoniae but H. flu can also cause this
  • Otitis media
  • Bronchitis
  • Conjunctivitis
44
Q

Haemophilus ducreyi

A
  • causes chancroid
    • painful genital ulcer
    • contrast with Chancre (syphilis): non painful
  • sexually transmitted
  • Tx
    • Azithromycin/Ceftriaxone
45
Q

Causes and features of genital ulcers

A
  • Syphilis
    • painless chancre
  • H. ducreyi
    • Painful chancroid
  • Herpes
    • Multiple vesicles/ulcers
  • Lymphogranuloma venereum
    • large swollen lymph nodes (buboes)
46
Q

Bordetella pertussis

A
  • Vaccination available so not common anymore
  • Causes whooping cough
  • URI with severe coughing
  • classic presentations
    • Paroxysms of coughing
    • Inspiratory “whoop”
    • Post-cough vomiting
    • Exhaustion from coughing
  • coughing fits last weeks
  • Known as the 100-day cough
47
Q

Bordetella pertussis features

A
  • Transmitted by aerosolized droplets
  • Pertussis toxin
    • Shown to inhibit Gi proteins
    • Allows over-activation of adenylate cyclase
    • increase cAMP levels in cells in neutrophils
    • result: impaired recruitment of neutrophils
  • Toxin may not be the cause of cough
    • some species without toxin also cause symptoms
48
Q

Bordetella pertussis vaccine

A
  • acellular pertussis vaccines used
  • contain purified pertussis antigens
49
Q

Yersinia enterocolitica features

A
  • found in domesticated animals (dogs) and pigs
  • Often transmitted through contaminated pork
  • Also from contaminated water or milk
  • Fever
  • Abdominal pain
  • Nausea
  • vomiting
  • Bloody diarrhea
  • can cause inflammation around appendix or in mesenteric lymph nodes (mesenteric adenitis)
    • may mimic Crohns or appendicitis
  • dont confuse with Yersinia pestis (plague)

Infectious Disease (82 decks)

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