2. Prof. Abdullah Akhtar AhmedProf. Abdullah Akhtar Ahmed
Professor of MicrobiologyProfessor of Microbiology
Ibrahim Medical CollegeIbrahim Medical College
Shahbagh, DhakaShahbagh, Dhaka

3. A. Gram Positive Cocci
 PeptostreptococcusPeptostreptococcus
 P. magnusP. magnus
 P. asaccharolyticusP. asaccharolyticus
 P. prevotiiP. prevotii
 P. anaerobiusP. anaerobius
 PeptococcusPeptococcus
 P. nigerP. niger
 Sarcina ventriculiSarcina ventriculi
PeptostreptococcusPeptostreptococcus
 N flora of mouth, upperN flora of mouth, upper
respiratory tract,respiratory tract,
intestinal tract, vagina &intestinal tract, vagina &
skinskin
 20-40% of anaerobic20-40% of anaerobic
infectionsinfections
 Brain abscessBrain abscess
 PleuropulmonaryPleuropulmonary
infectionsinfections
 Female genital tractFemale genital tract
infectioninfection
Non Sporing Anaerobe

4. Non Sporing
Anaerobe
VeillonellaVeillonella
C. Gram Positive BacilliC. Gram Positive Bacilli
1. Lactobacillus1. Lactobacillus
2. Bifidobacterium2. Bifidobacterium
3. Actinomyces3. Actinomyces
D. Gram Negative BacilliD. Gram Negative Bacilli
1. Bacteroides1. Bacteroides
2. Fusobacterium2. Fusobacterium
3.3. PrevotellaPrevotella
4. Porphyromonas4. Porphyromonas
E. SpirochetesE. Spirochetes
1. Treponema1. Treponema
2. Borrelia2. Borrelia
B. Gram negative cocci

5.  Gram positive bacilli.Gram positive bacilli.
 MicroaerophilicMicroaerophilic
 Grow in presence of COGrow in presence of CO22 and at pH 3.0and at pH 3.0
 Widely distributed as saprophytes in fermentingWidely distributed as saprophytes in fermenting
animal and vegetable material (e.g. milk, cheese)animal and vegetable material (e.g. milk, cheese)
 Normal flora of man and animal in the mouth, gutNormal flora of man and animal in the mouth, gut
and vagina.and vagina.
 Older textbooks have used the term “Older textbooks have used the term “DoderleinsDoderleins
bacillusbacillus” for a variety of human vaginal strains of” for a variety of human vaginal strains of
Lactobacillus.Lactobacillus.
Lactobacillus

6. Gram Stained Vaginal smear

7. Role
 L. acidophilusL. acidophilus synthesize biotin, Vit. Bsynthesize biotin, Vit. B1212
and Vit. K in the intestine.and Vit. K in the intestine.
 It ferment glycogen which is deposited inIt ferment glycogen which is deposited in
the vaginal epithelial cells and form lacticthe vaginal epithelial cells and form lactic
acid. This lactic acid prevent growth ofacid. This lactic acid prevent growth of
other bacteria by maintains highly acidic pHother bacteria by maintains highly acidic pH
of the vagina.of the vagina.

8. Bacteroides
 B. fragilisB. fragilis is most significant.is most significant.
 Pale irregularly stainingPale irregularly staining Gram negative bacilli/Gram negative bacilli/
coccobacilli with polysaccharide capsule.coccobacilli with polysaccharide capsule.
 PleomorphicPleomorphic
 Normal flora of large intestine & female genitalNormal flora of large intestine & female genital
tract. Normal stool contain 11tract. Normal stool contain 111010
B. fragilisB. fragilis
organisms per gram.organisms per gram.
 Cause abdominal, lung and brain abscesses andCause abdominal, lung and brain abscesses and
wound infectionwound infection

9. Bacteroides

10. Bacteroides Virulence Factors
 Polysaccharide capsulePolysaccharide capsule
 LipopolysaccharideLipopolysaccharide
 AgglutininAgglutinin
 Histolytic enzymeHistolytic enzyme
 Oxygen toleranceOxygen tolerance
 ββ lactamaselactamase

11. Fusobacterium
 Delicate gram negative rodsDelicate gram negative rods
 Tapering endsTapering ends
 F. nucleatumF. nucleatum
 Mouth, Upper Resp. tract, GI tract,Mouth, Upper Resp. tract, GI tract,
Genital tractGenital tract
 Head, neck and lower respiratoryHead, neck and lower respiratory
tract infectionstract infections
 F. necrophorumF. necrophorum
 Anaerobic tonsillitis/pharyngitisAnaerobic tonsillitis/pharyngitis
 Involve jugular veinInvolve jugular vein  SepsisSepsis
 Lemierre's diseaseLemierre's disease

12.  Lemierre's syndromeLemierre's syndrome (or(or Lemierre's diseaseLemierre's disease) is a disease usually) is a disease usually
caused by the bacteriumcaused by the bacterium Fusobacterium necrophorumFusobacterium necrophorum, and, and
occasionally by other members of the genusoccasionally by other members of the genus FusobacteriumFusobacterium ((F.F.
nucleatum, F. mortiferum and F. variumnucleatum, F. mortiferum and F. varium etc.) and usually affectsetc.) and usually affects
young, healthy adults. Lemierre's syndrome develops most oftenyoung, healthy adults. Lemierre's syndrome develops most often
after a strep sore throat has created a peritonsillar abscess, a craterafter a strep sore throat has created a peritonsillar abscess, a crater
filled with pus and bacteria near the tonsils. Deep in the abscess,filled with pus and bacteria near the tonsils. Deep in the abscess,
anaerobic bacteria (microbes that do not require oxygen) likeanaerobic bacteria (microbes that do not require oxygen) like
Fusobacterium necrophorum can flourish. The bacteria penetrateFusobacterium necrophorum can flourish. The bacteria penetrate
from the abscess into the neighboring jugular vein in the neck andfrom the abscess into the neighboring jugular vein in the neck and
there they cause an infected clot (there they cause an infected clot (thrombosisthrombosis) to form, from which) to form, from which
bacteria are seeded throughout the body by the bloodstreambacteria are seeded throughout the body by the bloodstream
(bacteremia). Pieces of the infected clot break off and travel to the(bacteremia). Pieces of the infected clot break off and travel to the
lungs as emboli blocking branches of the pulmonary artery bringinglungs as emboli blocking branches of the pulmonary artery bringing
the heart's blood to the lungs. This causes shortness of breath, chestthe heart's blood to the lungs. This causes shortness of breath, chest
pain and severepain and severe pneumoniapneumonia. Fusobacteria are normal inhabitants of. Fusobacteria are normal inhabitants of
the oropharyngeal flora. This is a very rare disease with onlythe oropharyngeal flora. This is a very rare disease with only
approximately 160 cases in the last 100 years.approximately 160 cases in the last 100 years.[1][1]

13. Prevotella & Porphyromonas
 Small, pale stainingSmall, pale staining
gram negativegram negative
coccobacillicoccobacilli
 Dental plaque andDental plaque and
gingival crevicesgingival crevices
 Infections of oral cavityInfections of oral cavity
and upper respiratoryand upper respiratory
tracttract

14. Prevotella and Porphyromonas
 Some species produce a dark pigmentSome species produce a dark pigment

15. Pathogenicity
 AdherenceAdherence :: agglutinate RBCagglutinate RBC
fimbriaefimbriae
 CapsuleCapsule :: acidic polysaccharides,acidic polysaccharides,
phagocytosis by WBCphagocytosis by WBC
 EnzymesEnzymes :: collaginase, protease,collaginase, protease,
hyaluronidase, fibrinolysin, DNAse,hyaluronidase, fibrinolysin, DNAse,
…, etc.…, etc.
 EndotoxinEndotoxin (LPS) :(LPS) : activate C3activate C3
pathway, PMNspathway, PMNs

16. Pathogenicity
• Beta-lactamase productionBeta-lactamase production
• B. fragilisB. fragilis – protect themselves and other– protect themselves and other
species in mixed infectionsspecies in mixed infections
• Superoxide dismutase productionSuperoxide dismutase production
• Protects bacteria from toxic OProtects bacteria from toxic O22 radicals asradicals as
they move out of usual nichethey move out of usual niche

17. Anaerobes Commonly Encountered in
Infection
Hundreds of anaerobes are part of normal human floraHundreds of anaerobes are part of normal human flora 
Only few cause significant infectionsOnly few cause significant infections
 Account for 2/3 of clinically significant anaerobicAccount for 2/3 of clinically significant anaerobic
infections:infections:
 Bacteroides fragilisBacteroides fragilis groupgroup
 PrevotellaPrevotella andand PorphyromonasPorphyromonas
 Fusobacterium nucleatumFusobacterium nucleatum
 PeptostreptococcusPeptostreptococcus
 Clostridium perfringensClostridium perfringens
 Pathogenic species have “virulence factors” that allowPathogenic species have “virulence factors” that allow
survival outside their niche and to cause diseasesurvival outside their niche and to cause disease

18. Importance of nonsporing anaerobes
 Opportunistic pathogens cause disease in cases ofOpportunistic pathogens cause disease in cases of
lowered host’s immunity:lowered host’s immunity:
1.1. TraumaTrauma
2.2. Tissue necrosisTissue necrosis
3.3. Impaired circulationImpaired circulation
4.4. AIDSAIDS
5.5. Administration of antibiotics, corticosteroids &Administration of antibiotics, corticosteroids &
cytotoxic drugs.cytotoxic drugs.
6.6. DiabetesDiabetes
7.7. MalnutritionMalnutrition
8.8. MalignancyMalignancy

19. “MORE IS MISSED BY NOT LOOKING
THAN BY NOT KNOWING”
Anonymous
Patient examination in the Intensive Care Unit

20. Thank you
Life is the flower for which love is the honey.
Victor Hugo

21. SAQ – Non sporing anaerobe
1. Classify non sporing anaerobic bacteria.
2. Enumerate the medically important non
sporing bacteria.
3. Mention important role of Lactobacilli.
4. Write down the biological property and
pathogenesis of B. fragilis.
5. Mention important characteristics and
pathogenesis of Fusobacterium.
6. Why non sporing anaerobes are medically
important?