non sporing anaerobes-microbiology
DESCRIPTION
TRANSCRIPT
Non sporing anaerobes
Growth pattern depending upon oxygen requirement
Introduction
Neglected in diagnostic labs- but they outnumber the aerobic bacteria including most sites of human and animal body.
Mouth and skin -10-30 times more frequent than aerobic bacteria.
The numbers of anaerobes have been estimated to be 10 4-10 5/ml in small intestine,10 8/ml in saliva and 10 11/g in the colon
Classification
Earlier-coloney morphology,biochemical reactions and antibiotic sensitivity pattern.
Current classification-based on DNA base composition and analysis of fatty acids, end products of metabolism
Aerobes and facultative anaerobes have metabolic systems listed below, whereas anaerobic bacteria do not
▪ Cytochrome system of metabolism of oxygen.▪ Superoxide dismutase, which catalyses the
following reaction:▪ O-
2+O-2----H2O2+O2
▪ Catalase, which catalyses the following reaction.
▪ 2H2O2----2H2O+O2 (gas bubbles).
Anaerobic bacteria do not have cytochrome systems for metabolism.
Less fastidious anaerobes have low levels of superoxide dismutase and may not have catalase.
Obligate anaerobes usually lack superoxide dismutase and catalase and are susceptible to lethal effects of oxygen radicals.
Most human infections are caused by moderately obligate anaerobes.
Ability to tolerate oxygen varies from species to species.
Cocci
Gram positive
peptostreptococcus
peptococcus
Gram negative
Veillonella
Bacilli
Endospore forming
Clostridia
EUBACTERIUMPROPIONIBACTERIUM
LACTOBACILLUSMOBILUNCUS
BIFIDOBACTERIUMACTINOMYCETS
BACTER OIDESPREVOTELLA
PORPHYROMONASFUSOBACTERIUM
LEPTOTRICHA
Spirochetes
Spirochetes
Treponema Borrelia
Divided into Gram positive and Gram negative cocci
Peptococci,peptostreptococci.-cocci small size 0.2-2.5 µ. Many aerotolerent.
Normal flora of vagina,intestines and mouth.
Peptostreptococcus anaerobicus-puerperal sepsis.
P.magnus-Abscess
Anaerobic cocciThey cause following
infectionsGenital infections,wound
infections,gangrenous appendicitis,urinary tract infections,osteomyelitis,abscess in the brain,lungs and other internal organs
Veillonellae
GNC of varying sizes occurring as diplococci,short chains or groups
They are normal inhabitants of mouth,intestinal and genital tract
All anaerobic cocci are generally sensitive to penicillin,chloramphenicol,and metronidazole and resistant to streptomycin and gentamicin
Gram positive bacilli
Eubacterium- periodintitis Lactobacillus usually non pathogenic L.catenaformae-bronchopulmonary
infections Bifidobacterium-branching Mobiluncus-M.mulieris,M.curtisii-
Bacterial vaginosis. What is bacterial vaginosis?
BACTERIAL VAGINOSIS
POLYMICROBIAL INFECTION OF VAGINA CHARACTERIZED BY THIN
MALODOUROUS VAGINAL DISCHARGEKOH TEST
VAGINAL PH IS MORE THAN 4.5CLUE CELL SEEN MICROSCOPICALLY
IN FRAM STAINED SMEARS-
Bifidobacterium
Bacteroids
Large group of GNB appear as slender rods or cocobacilli.
Normal commensal of intestine. Normal stool-1011 B.fragilis/gram. Commonly isolated-
B.fragilis,B.ovatus,B.distasonis,B.vulgatus,B.thetaiotamicron and others.
Contamination by contents of colon where they may cause suppuration-perotinitis
Constitutes less than 10% of Bacteroides species in the normal colon, however, is the most common isolate of anaerobes.
Major virulence factor: capsular polysaccharides, which may cause abscess formation when injected into the rat abdomen.
Resistant to penicillin.
Classification is based on colonial and biochemical features and characteristic short chain fatty acid patterns in gas liquid chromatography.
Associated with anaerobic cocci-peptostreptococci and others.
Prevotella
GNB-slender rods and cocobacilli Common-P.melaninogenica. Found in lung and brain abscess,in
empyema and in pelvic inflammatory diseases,and tuboverian abscess.
Often polymicrobial –peptostreptococci,anaerobic gram positive rods and fusobacterium species.
Black colonies produced by this. Colonies show-red fluorescence in UV rays
Porphyromonas
Normal oral commensal. Gingival, periapical tooth infections. More commonly-
breast,axillary,perianal and male genital infections
Fusobacteria
Pleomorphic GNB. Most species produce butyric acid
and convert threonine to propionic acid.
Isolated from mixed bacterial infections-oral infection pleuropulmonary sepsis.
L.buccalis-vincent’s fusiform bacillus-fusobacterium fusiformae
It causes Vincents angina-oropharyngitis
Leptotrichia
Anaerobic infections
Now-a-days techniques are simplified for their isolation & identification.
Endogenous infections. Precipitating factors are there. Anaerobic infections-polymicrobial
Trauma, tissue necrosis,foregin body, diabetes, malnutrition,malignancy, prolonged
treatment with aminoglycosides
Site and type of infection Bacteria commonly responsible
Central nervous system-brain abscess
B.fragilis,peptostreptococcus
ENT-chronic sinusitis,otitis media,mastoiditis,orbital cellulitis
Fusobacteria
Mouth and jaw-ulcerative gingivitis,dental abscess,cellulitis,abscess or sinus of jaw
Fusobacteria,spirochetes,mouth anaerobes,actinomycetes,
Respiratory-aspiration pneumonia,lung abscess,bronchiectasis,empyema
Fusobacteria,P.melaninogenica,anaerobic cocci,B.fragilis
Abdominal-shbphrenic,hepatic abscess,appenditicitis,peritonitis,ischiorectal abscess,wound infection after colorectal surgery
B.Fragilis
Female genitialia-purperal sepsis etc
P.melaninogenica,anaerobic cocci,B.fragilis
Skin and soft tissue Anaerobic cocci
Features that suggests anaerobic infections
Pus-putrid-foul smelling. Pronounced cellulitis.
Laboratory diagnosis
Interpretation should be done cautiously. Avoid resident flora contamination. Avoid or minimise the exposure with
oxygen. In laboratory exposure should me limited to
minimum Gram staining shows large variety of
different organisms and numerous pus cells Occasionally-brain abscess-single organism. UV examination-bright red fluorescence? Gas liquid chromatography
Swabs discouraged for anaerobic cultures
Culture
Freshly prepared blood agar with neomycin,yeast extract,hemin and vitamin K is adequate
Incubated at 37oC with 10%CO2. Gas pak Jar is used Examine plates after 24-48 hrs Parallel aerobic cultures shd. Be
always put.
1. Fluid media containing fresh animal tissue or 0.1% agar containing a reducing agent, thioglycollate.
3. Anaerobic glove chamber
2. Anaerobic jar
Methods for excluding oxygen
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