Anaerobes

Question 1

Aerotolerant

Answer 1

• 5% O2
• Actinomyces
• Bifidobacterium
• Clostridium

Question 2

Obligate Anaerobes

Answer 2

0% O2

• Prevotella
• Fusobacterium
• Bacteroides
• Lack superoxide dismutase

Question 3

Facultative Anaerobes

Answer 3

• Can grow in O2 but do not require it for metabolism

Question 4

Clostridium botulinum Characteristics

Answer 4

• Lipase positive (EYA) – a key marker for identification
• Gram stain: Gram-positive rod, obligately anaerobic, subterminal oval spores
• Natural reservoir: Soil and marine sediments world-wide
• Colony morphotypes: convex, raised or flat; round, irregular, entire or rhizoid borders
• Optimal temperature range: 4-37 C (type E as low as 4 C)

Question 5

BACTEROIDES FRAGILIS GROUP

Answer 5

* bile resistant
* resistant to kana, vanco, colistin disks
* most clinical isolates are catalase pos
* comprise 1/3 of clinical isolates
* most virulent (capsule)
* most antibiotic resistant
* Parabacteroides distasonis, merdae, goldsteinii

Question 6

PREVOTELLA SPECIES

Answer 6

• Isolated from oral and pelvic infections, abdominal and soft tissue
• Growth inhibited on BBE (but may turn agar black from hydrolysis of esculin if colonies plated directly)
• Resistant to kana, vanco, variable colistin
• Brick Red Fluorescense under UV
• Catalase usually negative

Question 7

PORPHYROMONAS SPECIES

Answer 7

• Brick red Fluorescence under UV
  **Human species:
• P. asaccharolytica (a-fucosidase- pos)
• P. gingivalis (trypsin pos)
• P. endodontalis
• P. uenonis (endodontalis, extra-oral)
• P. somerae (levii, human strain)
  * Animal species: cultured from bite wounds
• P. canoris, circumdentaria, cansulci, gingivicanis, gulae, levii, macacae, etc.
• Most are catalase positive

Question 8

FUSOBACTERIUM SPP

Answer 8

• S to kana, colistin disks; R to vanco
• indole positive; lipase negative
• slender rods with pointed ends
• several different colony types; subspecies
• Isolated from all types of infections and all areas of the body
• polymicrobial infections or single isolate
• LEMIERRE’S SYNDROME
• Or “post-anginal sepsis” (very rare) Occurs after prolonged or severe pharyngitis
• Septic thrombophlebitis with Fusobacterium necrophorum (probably from the mouth) associated with septic pulmonary emboli to the lungs

Question 9

“Bacteroides” ureolyticuslike
group

Answer 9

• Includes C.ureolyticus, Sutterella, other Campylobacter spp.,
• GNB sensitive to kana, colistin, R to vanco
• Small transparent/translucent colonies
• Pitting of agar is variable
• Most reduce NO3

Question 10

**Bilophila wadsworthia

Answer 10

• Original isolates from appendicitis
• Later from many other sources (chronic sinusitis, cholesteatom , pleural fluid, liver abscess, blood)
• Grows on BBE, black centers in colonies (H2S +)
• Catalase very positive !!!!!
• B-lactamase pos, resistant to many b-lactam agents

Question 11

GRAM-NEGATIVE COCCI

Answer 11

Question 12

“Anaerobic Streptococci”

Answer 12

• S. intermedius, S. constellatus, G. morbillorum previously classified as Peptococcus and Peptostreptococcus sp.
• Abiotrophia and Granulicatella (some grow better on anaerobe BA)
• initially may appear to be anaerobes
• eventually will grow in CO2
• Frequently recovered from abscess
• Resistant to metronidazole, most are
• susceptible to penicillin

Question 13

PROPIONIBACTERIUM ACNES

Answer 13

• Frequent skin contaminant in blood, csf cultures
• Occasionally pathogenic (shunts, implants, post-op cultures from eye)
• Relatively slow-growing
  * ID based on pos rxns for catalase, indole, nitrate
• Acne strains may be R to tetra and macrolides
• All strains R metronidazole

Question 14

**ACTINOMYCES SPECIES

Answer 14

• Many new species have been described,
• mostly from oral “mixed” infections.
• Important tests include pigment, catalase, nitrate, urease, esculin, carbohydrate fermentation, preformed enzymes
• Clinical isolates include A. israelii, A. odontolyticus, A. meyerii, A. turiscensis, A. neuii, and others
• Sulfur granules

Question 15

**CLOSTRIDIUM TETANI

Answer 15

• C tetani is found worldwide. Ubiquitous in soil, it is occasionally found in intestinal flora of humans and animals
• C.tetani is the cause of tetanus, or lockjaw.
• Spores are introduced into wounds by contaminated soil or foreign objects such as nails or glass splinters
• Morphology: long and slender; peritrichous flagella, no capsule, terminal located round spore(drum-stick apperance), its diameter greater than vegetative cell.
• Culture: obligate anaerobic; Gram(+); swarming occurs on blood agar, faint hemolysis.
• Biochemical activities: does not ferment any carbohydrate and proteins.
• Resistance: tolerates boiling for 60 min. alive after ten years in soil.
• Classification and Antigenic Types: C tetani is the only species. There are no serotypes
• Active immunity follows vaccination with tetanus toxoid

Question 16

**C. PERFRINGENS

Answer 16

• Box car shaped GPB
• Double zone of beta-hemolysis on BA
• Lecithinase positive
• Produces abundant gas in liquid media
• (blood culture bottles?)
• Gas gangrene is a life-threatening disease with a poor prognosis and often fatal outcome.
• Initial trauma to host tissue damages muscle and impairs blood supply—-lack of oxygenation
• Initial symptoms : fever and pain in the infected tissue.;more local tissue necrosis and systemic toxemia.
• Infected muscle is discolored (purple mottling) and edematous and produces a foul-smelling exudate; gas bubbles form from the products of anaerobic fermentation.
• Enterotoxin producing strains.
• These bacteria are found in mammalian feces and soil.

Question 17

**CLOSTRIDIUM DIFFICILE

Answer 17

• PMC and antibiotic associated colitis
• Also isolated from clinical specimens
• Resistant to cefoxitin –grows on CCFA
• Vegetative cells are oxygen sensitive!
• Pseudomembranous colitis (PC) results predominantly as a consequence of the elimination of normal intestinal flora through
  antibiotic therapy.
• Symptoms include abdominal pain with a watery diarrhea and leukocytosis.
• “Pseudomembranes” consisting of fibrin, mucus and leukocytes can be observed by colonoscopy.
• Untreated pseudomembranous colitis can be fatal in about 27-44%.

Question 18

**C. BOTULINUM

Answer 18

• Anaerobic
• Gram-positive
• rod-shaped
• sporeformer
• produces a neurotoxic protein.
• soil, sediments of lakes, ponds, decaying vegetation.
• intestinal tracts of birds, mammals and fish.

Question 19

**ANAEROBIC COCCI

Answer 19

Classification
** Peptococcus
* Peptostreptococcus – anaerobic coccus most often associated with human disease
* Veillonella*
* All can be found as NF of oral cavity, Genital and urinary tracts, G.I. tract , and skin
* Morphology and general characteristics
* Peptococcus G+C; 1 species, P. niger, produces black colonies
* Peptostreptococcus G+C; 9 species. P. anaerobius is the most commonly isolated species