Micro Exam 2 Book Lecture

Front 1

The most important genera of anaerobic Gm- bacteria of the upper respiratory, gastrointestinal and genitourinary tracts.

Back 1

the genera Bacteroides, Fusobacterium, Prophyromonas, and Prevotella and the cocci in the genus Veillonella

Front 2

The most important endogenous anaerobic pathogen

Back 2

 Bacteroides fragilis

Front 3

Genera stimulated or inhibited by 20% bile present in cultivation media.

Back 3

Bacteroides stimulated - prophyromonas and prevotella are inhibited

Front 4

Genera or bacterial types of Gm- bacteria with strong or weak endotoxin activity

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- Bacteroides have little or no endotoxin activity because the lipid A component of LPS lack phosphate groups on the glucosamine residues and the number of fat acids linked to the amino sugars is reduced

Front 5

Mechanisms responsible for adherence to epithelial cells

Back 5

B. fragilis and Prevotella melaninogenica strais can adhere to peroneal surfaces more effectively than other anaerobes because their surface is covered with polysaccharide capsule. B. fragilis and other bacteroides and P. gingivales can adhere to epithelial cells and extracellular molecules

Front 6

Mechanisms responsible for avoiding antibacterial immune mechanisms

Back 6

proteases produced by porphyromonas and prevotella species that degrade immunoglobulins. The capsular polysaccharide is antiphagocytic. Also, the short chain fatty acids produced during anaerobic metabolism inhibit phagocytosis and intracellular killing.

Front 7

Mechanisms responsible for avoiding oxygen toxicity

Back 7

Bacteria that can cause disease can also tolerate oxygen exposure. Catalase and superoxide dismutase can inactivate hydrogen peroxide and the superoxide free radicals are present in pathogenic strains.

Front 8

Mechanisms responsible for tissue destruction

Back 8

Cytotoxic enzymes associated with gram neg anaerobes. Found in both virulent and avirulent isolates. This can cause tissue destruction, inactivate immunoglobulins and resist oxygen toxicity (superoxide simutase) most likely plays an important role in the pathogenesis of anaerobic infections

Front 9

Toxin responsible for diarrheal disease produced by B. fragilis

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enterotoxigenic strains in B fragilin cause diarrhea by produce a heat labile zinc metalloprotease toxin BFT. This cause a morphological change on the intestinal epithelia via f actin arrangement with the resultant stimulation of chloride secretion and fluid loss

Front 10

Epidemiology

1. Protective or supportive functions of endogenous anaerobic Gm- bacteria

Back 10

can stabilize the resident bacterial flora, preventing colonization by pathogenic organisms from exogenous sources, and aiding in the digestion of food.

Front 11

How Gm- anaerobes transition from supportive to pathogenic bacteria.

Back 11

when they move from their endogenous home to normally sterile sites and are characterized by polymicrobial mixture of organisms

Front 12

Gm- anaerobic bacteria involved in brain abscesses

Back 12

- Prevotella, porphyromonas, fusobacterium, peptostreptococcus, and other anearobic and aerobic cocci

Front 13

Gm- anaerobic bacteria involved in intraabdominal infections

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- Prevotella, porphyromonas, fusobacterium, peptostreptococcus, and other anearobic and aerobic cocci

Front 14

Gm- anaerobic bacteria involved in gynecologic infections (species

Back 14

- Prevotella bividia, prevotella disiens, and B fragilis

Front 15

Gm- anaerobic bacteria involved in skin and soft tissue infections (species

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Peptostreptococcus, propinibacterium and B fragilis

Front 16

Gm- anaerobic bacteria involved in bacteremia (species)

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- Anaerobes were at one time responsible for more than 20% of bacteremia but now it is only 1 to 3%
- B fragilisis most common

Front 17

Gm- anaerobic bacteria involved in gastroenteritis (species)

Back 17

Strains of enterotoxin producing B fragilis

Front 18

Gm- anaerobic bacteria involved in chronic infections of sinuses, ears and peridontium (genera)

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- Prevotella, porphyromonas, fusobacterium and non-fragilis bacteroides

Front 19

Gm- anaerobic bacteria which produce beta-lactamases

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all members of B fragilis group, many prevotella and porphyromona species and some fusobacterium

Front 20

Antibiotics or agents effective against Gm-anaerobes

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metranidazole, carbapenems (imipenem)and beta-lactam-beta-lactamase inhibitors (peperacillin-taxobactam)

Front 21

Three general identifying characteristics of Campylobacter genus

Back 21

Thin, curved, gram neg rods

Front 22

he species of Campylobacter which is the major cause of gastroenteritis in the United States. The species of Campylobacter which causes bacteremia and septicemia

Back 22

C.jejuni

Front 23

General physiological structural and metabolic facts about Campylobacter, ie. size, cell wall type, structure of the major antigen of the genera, preferred gaseous environment, temperature preference.

Back 23

- Small 0.2 to 0.5 x 0.5 to 5 micrometer
- Comma shaped,
- Motile by means of flagella
- c.jejuni grows best at 42 than at 37

Front 24

Detailed pathogenic outcomes of Campylobacter infections by C. jejuni

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gastroenteritis, gastritis, septicemian and it is common

Front 25

Detailed pathogenic outcomes of Campylobacter infections by C. coli

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gastroenteritis, septicemia, insects, abortion, spontaneous, meningitis and it is uncommon

Front 26

Detailed pathogenic outcomes of Campylobacter infections by C. upsaliensis

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gastroenteritis, septicemia, abscesses and it is uncommon

Front 27

Detailed pathogenic outcomes of Campylobacter infections by C. fetus

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septicemia, gastroenteritis, spontaneous abortion, meningitis. Has the propensity to spread from the gastrointestinal tract to the bloodstream and distal foci. It is resistant to complement and antibody mediated serum killing.

Front 28

Generally how Guillain-Barre syndrome is caused by Campylobacter species.

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- Associated with c. jejuni and c. upsaliensis. Guillain Barre syndrome is an autoimmune disorder of the peripheral nervous system characterized by development of symmetrical weakness over secveral days and recovery requiring weeks to months. This syndrome is associated with specific serotypes primary c. jejuni. . It is due to a cross reactivity between oligosacchraides of campy and glycosphingolipids present on the surface of neutral tissues

Front 29

Effect of immunity and immune status of the patient on infections with C. jejuni and C. fetus. Why C. fetus is more resistant to immune mechanisms.

Back 29

C. fetus is more resistant to immune mechanisms because it is covered by a heat stable, capsule like proteins (s protein) that precents complemnt mediated killing in serum (inhibition of c3b binding to the bacteria). If it loses this protein then c. fetus will no longer be virulent. C. jejuni on the other hand is killed rapidly

Front 30

Campylobacter infections are zoonotic. Know what that means and how this trait results in diseases.

Back 30

Zoonotic means that animals are the reservoirs for infection. For example humans acquire infection with c. jejuni and c. coli after consumption of contaminated food, milk or water. c. upsaliensis infection are acquired by domestic dogs. Food products that reduce the neutralize gastric acids can reduce the infectious dose

Front 31

How Campylobacter survives gastric stomach acids to become pathogenic

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there are conditions that decrease or neutralize the gastric acid secretion to favor the disease. If the organism is expose to the gastric acids then it would be killed, so eating foods like yogurt will decrease the gastric acidity.

Front 32

How Campylobacter is presumptively identified.

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Can be recognized by its farting motility, so it can be detected bon dark field or phase contrast microscopy in freshly collected stools specimens. The organism appear as small, curved rods arranged either singly or in end to end pairs resembling an S shape

Front 33

General management of Campylobacter infections.

Back 33

campy is self limiting that can be managed by the replacemen of lost fluids and electrolytes. Antibiotics can be used for severe infections such as macrolides, erythromycin, axitrhomycin, clarthomycin, tetracyclines, aminoflycosides, chloramphenicol, fluoroquinolones, clinda,ycin, amoxicillin, clavulanic acid, imipenem

Front 34

Antibiotics of choice for Campylobacter infections. Antibiotics they are resistant to.

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resistant to penicillins, cephalosporin, sulfonamide. Erythromycin is the antibiotic of choice 

Front 35

How exposure to Campylobacter can be prevented.

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prevention by proper preparation of food particularly porultry and avoiding unpasterurized dairy products and implemnentation of safeguards to prevent contamination of water supplies