Anaerobic Infection & Normal Flora

Question 0

Abscess formation, foul discharge, gas formation, necrosis, and predisposing conditions such as pulmonary aspiration, bowel surg, bad dental hygiene, bites, and trauma are all common features of:

Answer 0

Anaerobic infection

Question 1

T/F: most anaerobic infections are caused by a single species

Answer 1

FALSE; most anaerobic infections are mixed with multiple anaerobes or facultative aerobes.

Most aerobic infections are due to a single organism.

Question 2

Most anaerobic infections are caused by/from:

Answer 2

The patient’s endogenous flora!

Question 3

Bacteroides Fragilis infections (are/are not) penicillin resistant and are found (above/below) the diaphragm.

Answer 3

B. Fragilis infections are penicillin resistant and are found below diaphragm.

Question 4

Bacteroides Fragilis are what shape

Answer 4

PLEOMORPHIC, but most commonly GM - rods

Question 5

T/F: Bacteroides Fragilis are found in small numbers within the human large intestine

Answer 5

FALSE: THEY ARE FOUND IN LARGE-ASS NUMBERS 10^11 CFU per gram of poo

Question 6

T/F: B. Fragilis can resist the bactericidal action of bile

Answer 6

TRUE

Question 7

B. Fragilis and C. Perfringens together acccount for ___% of anerobic septicemias; ___% of all septicemias are anaerobic.

Answer 7

80%

10%

Question 8

Extraintestinal infection by B fragilis may result in septicemia as a result of:

Answer 8

Bowel rupture, female genital infections -> abscess following birth, induced abortion, infected IUD

Question 9

Name the most important anaerobe that is PENICILLIN RESISTANT:

Answer 9

B. Fragilis <- memorize this as penicillin resistant

Question 10

The majo virulence factor for B. Fragilis is:

Answer 10

Its Capsule. Only encapsulated strains produce abcesses

Question 11

Prevotella Melaninogenicus is a GM (+/-) ______

Answer 11

GM - rod

Question 12

This bacterium along with other anaerobes, is a serious cause of periodontal dissease, sometime found in genital infections. Many strains are penicillin sensitive. Its name derives from ‘black pigment’ - hemin, that is required for its growth.

Answer 12

Prevotella melaninogenicus

Question 13

This gram - rod species has TAPERED ENDS and are VERY THIN, they are penicillin and oxygen sensitive, and important causes of oral infection, lung abcess and abdominal infections

Answer 13

Fusobacterium

Question 14

This gramm + rod is normal flora in the intestine + vagina, and important for maintaining low pH and preventing growth of pathogens by converting sugar to lactate. It is a non-pathogen. Some strains are used to make yogurt milk etc.

Answer 14

Lactobacillus

Question 15

An infection by this GM positive branching rod species might be involved in cervico-facial, lung, or abdominal infections with SINUS TRACTS. Its microcolonies would be characterized by yellow SULFUR GRANULES

Answer 15

ACTINOMYCES

Question 16

This GM + coccus anaerobe grows in chains and is part of normal mouth gut and urogenital flora. It may be found in pleuro-pulmonary, brain abcess, or OBGYN infections.

Answer 16

Peptostreptococcus

Question 17

Treatment hierarchy for anaerobic infections (7)

Answer 17

1. Penicillin! (EXCEPT FOR B. FRAGILIS -> don’t use alone for infection below diaphragm!!!)
2. Clindamycin
3. new cephalosporins (EFFECTIVE FOR B. FRAGILIS)
4. chloramphenicol
5. Metronidazole
6. Gentamicin+ cefoxitin or + clindamycin for MIXED aerobe/anaerobe infection
7. Surgical drainage for any acesses

Question 18

Bacterial overgrowth in the small bowel can lead to: (2)

Answer 18

1. Fat malabsorption

2. Vitamin B12 deficiency

Question 19

Normal mouth flora:(5)

Answer 19

Viridans Streptococci
Neisseria Species
Diptheriods
Staphlococcus epidermidis
Eiknella corrodens

Question 20

Viridans Streptococci

Answer 20

GM+ cocci in chains. Large numbers - PREDOMINANT organisms of MOUTH. Common cause of SUBACUTE ENDOCARDITIS. Highly adherent to valves and teeth. Turnn sucrose into plaque + make lactate -> cavities.

Question 21

Diptheroids

Answer 21

Corynebacterium species other than c. diptheriae that are NON PATHOGENIC PLEOMORPHOC GM + rods. found in mouth. Also, MOST COMMON CAUSE OF BLOOD CULTURE CONTAMINATION because they also colonize skin

Question 22

Staphlococci epidermidisare the major species of ________ negative staphlococci in the oral flora. They appear as GM ____ ____________

Answer 22

Coagulase negative

Appear as GM + cocci in grape like clusters. Along with diptheriods, they are the most common causes of blood culture contamination.

Question 23

Common anaerobes in oral cavity & sensitivity (4)

Answer 23

1. Fusobacterium, penicillin sensitive
2. Prevotella, penicillin sensitive
3. Streptococci such as petptostreptococcus, penicillin sensitive
4. Actinomyces

Question 24

T/F: anaerobes of the oral cavity (fuso, prevotella, etc) do NOT extend into the lower trachea in healthy individuals.

Answer 24

True!

Question 25

Gastric achlorhydria

Answer 25

abnormality with no stomach acid -> bacteria CAN proliferate in stomach. Normally bacteria CANNOT be cultured due to the acid.

Question 26

T/F: the upper small bowel is generally sterile

Answer 26

TRUE. sterility due to rapid movement and peristalsis and unconjugated bile acids. Bacteria may increase here in the event of obstruction.

Question 27

T/F: the terminal ileum is sterile

Answer 27

False. Normally houses about 10^6 bacteria due to stasis

Question 28

In the colon there is marked bacterial proliferation; metabolic activity of bacteria results in ammonia, acid, and gas production. HOW IS THE AMMONIA FORMED?

Answer 28

the bacteria split UREA to form protein

Question 29

Patient ruptures a bowel, what bacteria is a frequent cause of the following intrabadominal infection? What drug should you use?

Answer 29

BACTEROIDES FRAGILLIS is the MOST COMMON species in STOOL. it is penicillin RESISTANT USE CLINDAMYCIN, CEFOXITIN, OR METRONIDAZOLE for BELOW THE DIAPHRAGM infections

Question 30

Establishing flora: 1. Fetal 2. Born 3. And then...

Answer 30

Fetal intestine is sterile very very very few bacteria @ birth, but intestine is colonized within hours Flora of breast fed infants = BIFIDOBACTERIUM Weaning->-> adult like flora

Question 31

Regarding bile acid, what is the consequence of abnormal bacterial growth in the upper small intestine?

Answer 31

BILE ACID DECONJUGATION: Bacterial growth will convert more conjugated bile acid into FREE BILE ACID, causing fat malabsorption.

Question 32

What is a hepatic coma and how is it treated

Answer 32

if liver fxn is imparied, blood ammonia levels rise. Treatment = reducing the normal intestinal flora, because their conversion of protein is a major source of ammonia to the blood.

Question 33

Intestinal flora are responsible for converting bilirubin to ____ & ______

Answer 33

Urobilin and sterobilin

Question 34

What is the fate/significance of carbs that are not absorbed by the host?

Answer 34

The carbs are FERMMENTED by intestinal flora, causing a drop in pH; the low pH helps maintain the gut flora.

Question 35

Normal flora of skin is ~_____ CFU per cm^2 of skin

Answer 35

10^3 - 10^4

Question 36

What are the 3/4 major normal flora of the skin?

Answer 36

Staph Epidermidis - Predominant, normally non-pathogenic Staph Aureus skin + nares Diptheriods #4 - other anaerobes like proprionibacterium in deep follicles (acnes)

Question 37

Normal flora of GU tract

Answer 37

Lactobacillus -> responsible for pH in vagina E. Coli from colon 20% women have Group B streptococcus in vagina too -> newborn sepsis.