UII ANAEROBnmugku

7/27/2019 UII ANAEROBnmugku

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ANAEROBES

BACTERIA

Titik Nuryastuti

Microbiology DepartmentFac of Medicine UGM


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Classification of Medically

Important Anaerobes

Grampositivecocci

Peptostreptococcus

Gramnegativecocci

Veillonella

Grampositivebacilli Clostridiumperfringens,tetani,botulinum,difficile

Propionibacterium

Actinomyces

Lactobacillus

Eubacterium,bifidobacterium,arachnia

Gramnegativebacilli Bacteroidesfragilis

Fusobacterium

Prevotella

Porphyromonas


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Definitions

Anaerobes

Bacteria that require anaerobic conditions to initiate and sustain

growth

No Ability to live in oxygen environment

Ability to utilize oxygen for energy instead of fermentation or

anaerobic respiration (except obligate anaerobe) Strict (obligate) anaerobe

Unable to grow if > than 0.5% oxygen

Moderate anaerobes

Capable of growing between 2-8% oxygen

Microaerophillic bacteria Grows in presence of oxygen, but better in anaerobic conditions

Facultative bacteria (facultative anaerobes)

Grows both in presence and absence of oxygen


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Metabolism


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Growth anaerobic bacteria in GAM


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Epidemiology

Endogenous infections

Indigenous microflora

Skin: Propionibacterium, Peptostreptococcus

Upper respiratory: Propionibacterium

Mouth: Fusobacterium, Actinomyces Intestines: Clostridium, Bacteroides, Fusobacterium

Vagina: Lactobacillus

Flora can be profoundly modified to favor anaerobes

Medications: antibiotics, antacids, bowel anti-motility agents

Cancers Exogenous infections

Spore forming organisms in soil, water, sewage


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Role of Anaerobes

Prevent colonization & infection by

pathogens

Bacterial interference through elaboration of

toxic metabolites, low pH, depletion ofnutrients

Interference with adhesion

Contributes to host physiology Bacteroides fragilis synthesizes vitamin K and

deconjugates bile acids


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Clinical features of anaerobic

infections

The source of infecting micro-organism is

the endogenous flora of host

Alterations of hosts tissues provide suitableconditions for development of opportunist anaerobic

infections

Anaerobic infections are generally

polymicrobial Abscess formation

Exotoxin formation


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Virulence factors

Attachment and adhesion

Polysaccharide capsules and pili

Invasion

Aerotolerance Establishment of infection

Polysaccharide capsule (B. fragilis) resists

opsonization and phagocytosis

Synergize with aerobes Spore formation (Clostridium)

Tissue damage

Elaboration of enzymes, toxins


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Sites of anaerobic infections


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Risk factor


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Anaerobic cocci

Epidemiology

Normal flora of skin, mouth, intestinal and genitourinary tracts

Pathogenesis

Virulence factors not as well characterized

Opportunistic pathogens, often involved in polymicrobial

infections Brain abscesses, periodontal disease, pneumonias, skin and soft

tissue infections, intra-abdominal infections

Peptostreptococcus

P. magnus: chronic bone and joint infections, especially

prosthetic joints

P.prevottiand P. anaerobius: female genital tract and intraabdominalinfections

Veillonella

Normal oral flora; isolated from infected human bites


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Anaerobic gram positive bacilli

No Spore Formation

Propionibacterium

P. acnes

Actinomyces

A. israelii

Lactobacillus Eubacterium, bifidobacterium, arachnia

Spore Formation

Clostridium

C.perfringens C. difficile

C tetani

C. botulinum


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Propionibacterium

Produces propionic acid as major by product of

fermentation

Colonize skin, conjunctiva, external ear,

oropharynx, female GU tract P. acnes

Acne

Resides in sebaceous follicles, releases LMWpeptide, stimulates an inflammatory response

Opportunistic infections

Prosthetic devices (heart valves, ventricularshunts)


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Actinomyces

Facultative or strict anaerobe

Colonize upper respiratory tract, GI, female GU

tract

Actinomycosis

Endogenous disease, no person-person spread Low virulence; development of disease whennormal mucosal barriers are disrupted (dentalprocedure)

Diagnosis made by examination of infected fluid:

Macroscopic colonies of organisms resemblinggrains of sand (sulfur granules)

Culture


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ACTINOMYCES

Anaerobic, filamentous, gram positive bacillus

Exhibit true branching

Mykes Greek forfungus

Thought by early microbiologist to be fungi

because of:

Morphology

Disease they cause


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Actinomycosis

Cervicofacial Actinomycosis

Poor oral hygiene, oral trauma,

invasive dental

procedure Chronic granulomatous

lesions that become

suppurative and form sinus tracts

Slowly evolving, painless process Treatment: surgical debridement and

prolonged penicillin


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Lactobacillus

Facultative or strict anaerobes

Colonize GI and GU tract

Vagina heavily colonized by Lactobacillus

crispatus &jensonii

Certain strains produces H2O2 which isbactericidal to Gardnerella vaginalis

Clinical disease (rarely)

Transient bacteremia from GU source

Bacteremia in immunocompromized host

Endocarditis


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Anaerobic gram negative bacilli

Bacteroides

B. fragilis

B. thetaiotaomicron

Fusobacterium

Prevotella

Porphyromonas


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Anaerobic gram negative bacilli

Clinical Diseases

Chronic sinus infections

Periodontal infections

Brain abscess

Intra-abdominal infection

Gynecological infection

Diabetic and decubitus ulcers


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Bacteroides

Epidemiology

B. fragilis associated with 80% of intra-abd infx

Peritonitis, intraabdominal abcesses

Diabetic foot ulcers

Pathogenesis

Polysaccharide capsule

Increases adhesion to peritoneal surfaces (along with fimbriae)

Protection against phagocytosis

Differs from LPS of aerobic GNR

Less pyrogenic activity

Abscess Formation

Produces superoxide dismutase and catalase Elaborate a variety of enzymes

Synergistic infections with aerobes


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How to diagnose anaerob infection

Foul-smelling discharge (due to short chain FAproduct of anerobic metabolism)

Infection in proximity to a mucosal surface

Gas in tissue (CO2 and H2)

Negative aerobic cultures

Medium can be used : TSA agar, BHI agar, Brucellaagar supplemented with hemin, blood, added withkanamycin (or other aminoglycosides)

-Incubates at 37C, in anaerobic conditions-Observe morphology, pigmentation, microscopicex., biochemical test


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Treatment

Mixed infection :

surgical drainage

Most active AB : clindamycin, metronidazole

Others : cephalosporine, piperacillin, penicillinG


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Conclusion

Anaerobic infections

Endogenous or exogenous

Alteration of host tissue

Break in anatomic barrier

Devitalized tissue

Polymicrobial

Synergy between anaerobes and facultative

bacteria

Abscess formation

Exotoxin elaboration


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Abscess Formation

Initial phase

Introduction of bacteria and inflammatory exudates (esp. fibrin)

Microbial persistence (localization)

Impaired bacterial clearance: fibrin deposition, platelet

clumping Impaired phagocytic function: fibrin, hemoglobin

Impaired neutrophil migration and killing: hypoxia, low PH

Complement depletion: necrotic debris

Development of mature abscess

Central core of necrotic debris, dead cells, bacteria Surrounded by neutrophils and macrophages

Peripheral ring of fibroblasts and smooth muscle cells within

collagen capsule


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clostridium


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Gram negative, pleomorphic bacilli

Resistance to PenG, Cephalosporin,

tetracycline

produce beta-lactamase

bile-tolerant


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ACTINOMYCOSIS

Not highly virulent (Opportunist) Component of Oral Flora

Periodontal pockets Dental plaque Tonsilar crypts

Take advantage of injury to penetrate mucosalbarriers Coincident infection Trauma Surgery


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Pulmonary Actinomycosis

15% of cases

Aspiration of organism from the oropaharynx

Slowly progressive process involving lung

and pleura May be mistaken for malignancy

Chest pain, fever, wgt loss and hemoptysis


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Form indurated masses with fibrous walls and centralloculations with pus Pus contains "Sulfur Granules"

Gritty, yellow white Average diameter - 2mm Composed of mineralized mycelial mass

Chronic infection

Form burrowing sinus tracts to skin or mucusmembranes Discharge purulent material

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