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Term 4: Infectious Diseases > Anaerobic Infections > Flashcards

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1

What is an anerobe?


organisms that requre reduced O2 for growth



i.e. fail to grow on the surface of solid media in 10% CO2 in air


2

What is the concept of colonization resistance?


concept that anaerobic bacteria occupy ecological niches that would otherwise be filled with potentially pathogenic organisms, by depleting oxygen & other nutrients, as well as producing various enzymes & toxic products.


3

What are the common characteristic of anaerobic infections?


-Frequently polymicrobial.



-Gas forming & foul smell.



-Failure to grow if not cultured properly under anaerobic conditions:



-do not respond to some usual antibiotics


4

Why are many anaerobic infections diagnosed late or not at all?

They fail to grow if not cultured properly under anaerobic conditions

5

What toxins are produced by C. difficile?


-Toxin A:  watery diarrhea



-toxin B:  cytotoxic to colon cells (degrades actin)



-Binary toxin:  increased virulence & resistance


6

What is the most common cause of marked leukocytosis?

-C. difficile

7

How is C. difficile diagnosed?

-PCR-based toxin gene testing

8

What is the most common scenario for botulism?


-Infants ingest spores, usually from honey



-progresses for 1-2 weeks



"floppy baby" syndrome


9

What are the symptoms of botulism?


-blurred vision



-diplopia



-ptosis



-expressionless facies



-regurgitation



-dysphagia


10

What are the important clinical features of botulism?


-No fever



-Symmetrical neurological manifestations



-Patients remain responsive



-Heart rate is normal or slow



-Sensory deficits do not occur


11

How do we treat botulism?


-botulism antitoxin



-only binds free toxin, current symptoms will not be reversed until later



-Human botulism immunoglobulin (infant botulism)


12

When does Clostridium tetani infection occur?

-acute injuries (punctures & lacerations)

13

What are the four clinical forms of disease caused by tetanus?


-localized tetanus



-facial tetanus (risus sardonicus)



-neonatal tetanus



-generalized tetanus


14

What symptom does generalized tetanus generally begin with?

-trismus (lockjaw)

15

How do we treat tetanus patients?


-Benzos for symptom relief -



abx: metronidazole or penicillin



-alpha and beta blockers



-passive & active immunization


16

What does Porphyromonas gingivalis cause?


-gingivitis


17

What are the 3 major aspiration syndromes?


-chemical pneumonitis 2' to gastric acid burns



-bronchial obstruction 2' to particulate matter



-bacterial aspiration syndromes


18

Is aspiration pneumonia more common in the right or left lung?


Right



-right main stem bronchus comes off at less of an acute angle


19

What are the Clinical Presentation of Anaerobic Pleuropulmonary Infections?


-Relatively insidious onset;



-Low-grade fever, malaise, weight loss, pleuritic chest pain & cough;



-Poor dental hygiene;



-Large amounts of sputum with foul taste:



*Odor of patient’s breath can be very offensive!


20

How do we diagnose aspiration pneumonia?


Sputum gram-stain is the diagnostic procedure of choice



*Anaerobic culture of expectorated sputum is unreliable, because of oral contamination.


21

What is a buzzword for actinomyces?

sulfur granules

22

What events can result in microorganisms within the peritoneal cavity?


-Organ perforation (ulcers, appendicitis, diverticulitis, etc.);



-Organ trauma (bullet, knife) or iatrogenic causes (“incidental” surgical accidents);



-Intraabdominal ischemia;



-Extension of inflammation or a preexisting infection.


23

What is 1' or spontaneous bacterial peritonitis?


-infections of the peritoneal cavity without an evident source



-usually caused by a single species of bug


24

When does spontaneous bacterial peritonitis occur?


-usually in kids with nephrotic syndrome, and adult cirrhotics



Children = S. pneumoniae



Adult = E. coli


25

What organisms are usually involved in pancreatic abscesses?


-E. coli



-enterococcus



-other enterobacteriaceae


26

How are splenic abscesses different from other abdominal abscesses?


-usually results from bacteremic spread



-associated with endocarditis & hemoglobinopatheis



-Usually S. aureus or S. penumo


27

What is the test of choice for diagnosis of abdominal infections/abscesses?

CT

28

A 39-year-old alcoholic man presented to the ER at BTGH with fever & productive cough. As you examine him, you note the particularly foul odor of his breath. The best diagnostic test in this case is:



A. Blood cultures



B. Chest CT scan



C. Sputum gram stain



D. Anaerobic sputum culture E. Acid fast smear


-C. Sputum gram stain



*Anaerobic sputum culture will be contaminated by oral bacteria



*The gram stain should show a mixture of different bacterial morphologies


29

This patient with chronic hepatitis C infection and ascites presented to the Emergency Room at the MEDVAMC with fever, confusion and abdominal pain. Paracentesis reveals 800 WBCs/UL in the ascitic fluid. The most likely cause of the infection is:



A. Pseudomonas aeruginosa



B. Staphylococcus aureus



C. Escherichia coli



D. Enterococcus faecalis


C. Escherichia coli =Spontaneous bacterial peritonitis


30

A 72-year-old smoker was diagnosed with squamous cell lung cancer as an outpatient. Bronchoscopy revealed almost total occlusion of the RUL bronchus. Two weeks later, he is admitted with fever, cough & sputum production. His sputum has a foul taste. There is a dense lobar consolidation in the RUL. What is the most likely bacteriology?

A. Pseudomonas aeruginosa/Klebsiella pneumoniae
B. Staphylococcus aureus
C. Legionella pneumophila
D. Prevotella melaninogenica/Peptococcus magnus/Fusobacterium necrophorum

D. Prevotella melaninogenica/Peptococcus magnus/Fusobacterium necrophorum