sporeforming & non-spore forming bacteria
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Prepared by: EGBII; 8-13-11
GRAM POSITIVE BACILLI DANILO D. DEVEZA JR., M.D.
Spore-Forming Gram Positive Bacilli Bacilli species - aerobic Clostridium species – non aerobic
Bacillus species
A. Bacillus anthracis B. Bacillus cereus Bacilli species
• Large aerobic, gram positive rods in chains • Most are saprophylic • Most do not cause disease • Important diseases: Anthrax, Food Poisoning • Spores located in center • Non-motile • “Cut glass” appearance in culture • Use nitrogen & carbon for energy • Spores are resistant to environmental changes, dry heat,
certain disinfectants
1. Bacillus anthracis • Anthrax: primarily disease of herbivores • Humans are infected incidentally • Acquired by the entry of spores
• Injured skin (cutaneous anthrax) • Mucous membrane (gastrointestinal anthrax) • Inhalation (inhalation anthrax)
PATHOLOGY
• Spores germinate in tissues at the site of entry • Formation of edema & congestion • Spread via lymphatics • Three Anthrax toxin
• Protective antigen (PA) • Edema factor (EF) • Lethal factor (LF)
• PA binds to specific cell receptors: entry of EF & LF • EF + PA = edema toxin • LF + PA = lethal toxin (virulence factor)
CLINICAL FINDINGS
• Humans: 95% (cutaneous), 5% (inhalation) • Cutaneous anthrax
• 1-7 days: pruritic rash
• Papule → vesicle → necrotic ulcer • Lesion has central black eschar • Edema, lymphangitis, lymphadenopathy • Healing by granulation & leaves a scar
• Incubation period: 6 weeks • Inhalation (Wool sorter’s disease)
• Hemorrhagic necrosis & edema of mediastinum • Pleural effusion
• Sepsis • GI: bowel ulceration • Brain: hemorrhagic menigitis
DIAGNOSTICS
• Specimem: fluid from local lesion, blood & sputum • Chains of large gram positive rods • Blood agar: non-hemolytic gray to white colonies, with
comma shaped outgrowths (Medusa head)
TREATMENT
• Ciprofloxacin: recommended • Penicillin G, Gentamycin, Streptomycin
PREVENTION
• Proper disposal of animal carcasses • Decontamination of animal products • Protective handling of potentially infected materials • Active immunization of domestic animals
2. Bacillus cereus • Produce toxins that cause disease
• Spores germinate, vegetative cells produce toxins
CLINICAL FINDINGS
• Emetic type (rice) • Nausea, vomiting, abdominal cramps • Self limiting
• Diarrheal type (meat dishes & sauces) • Diarrhea w/ abdominal pain & cramps • Enterotoxin : pre-formed or produced in the
intestine • Eye infections
• Organisms are introduced by foreign bodies • Local & systemic infections
• Endocarditis, meningitis, osteomyelitis • Presence of medical device (IV lines) & IV
drugs • Presence of B. cereus in stool is not diagnostic • 10
5 bacteria or more per gram of food is diagnostic
• Culture: exhibit motility “swarming”
TREATMENT
• Drug of choice: vancomycin or clindamycin • Resistant to penicillins & cephalosporins
Clostridium Species
Clostridium botulinium Clostridium tetani Clostridium perfringens Clostridium difficile Clostridium Species
• Large, anaerobic, gram (+), motile rods • Decompose proteins or form toxins or both • Spore is place centrally, sub-terminally or terminally • Produce large raised colonies (C. perfringens) • Small colonies (C. tetani) • Many produce hemolysis on blood agar (C. perfringens:
double zone) • Ferment a variety of sugars • Many digest proteins
1. Clostridium botulinium CHARACTERISTICS
• Causes Botulism • Found in soil • Produce toxins:
• Type A, B, E, occasionally F: human illness • Among the most toxic substances • Destroyed by heating for 20 mins at 100⁰C
PATHOGENESIS
• Illness is not infection • INTOXICATION • Toxins acts by blocking the release of acetylcholine at
synapses & neuromuscular junctions • FLACCID PARALYSIS
CLINICAL FINDINGS
• Visual disturbances • Dysphagia • Speech difficulty • Signs of bulbar paralysis • Cause of death: respiratory paralysis or cardiac arrest
Prepared by: EGBII; 8-13-11
TREATMENT
• Antitoxins (A, B and E) • Supportive • Ventilation
2. Clostridium tetani • Characteristics
• Gram (+) bacilli, terminal spores • Obligate anaerobes, motile
• Reservoir • Soil/ feces of animals
• Transmission • Puncture wounds/trauma • Requires low tissue oxygenation (Eh)
• LOCALIZED
PATHOGENESIS
• Spores germinate in the tissues: tetanospasmin • A fragment: blocks NT release at inhibitory
synapses • B fragment: mediates binding to neuron and cell
penetration of A fragment • Carried intra-axonally to CNS • Binds to ganglioside receptors • Blocks release of inhibitory mediators (glycine and
GABA) at spinal synapses
• Excitatory neurons are unopposed → extreme muscle spasm
CLINICAL FINDINGS
• Incubation period: 4 – 5 days (up to weeks) • Tonic contraction of voluntary muscles • Spasm first in area of injury, then the muscles of the jaw • External stimuli may precipitate muscle spasm • Death: spasm of respiratory muscles
TETANUS
• Trismus, risus sardonicus, opisthotonus
DIAGNOSIS: Clinical *
TREATMENT
• Hyperimmune human globulin (TIG) to neutralize toxin • + Metronidazole or Penicillin • Spasmolytic drugs (diazepam), debride, delay course
PREVENTION
• DTP, DTaP, Td • TIG • Proper wound care
Wound Management
3. Clostridium perfringens CHARACTERISTICS
• Encapsulated • Non motile • Double hemolysis • Ferment CHO • Reservoir: Soil and human colon • INVASIVE
TOXINS
• Alpha toxin (Lecithinase) • Necrotizing & hemolytic effect
• Theta toxin • Necrotizing & hemolytic effect
• DNase & Hyaluronidaes • Digest collagen
• Enterotoxin • Alters cell membrane, disrupting ion transport
PATHOGENESIS
• Spores germinate under anaerobic conditions in tissues • Distention of tissues &interference of blood supply,
presence of toxins • Spread of infection • Tissue necrosis • Hemolytic anemia • Severe toxemia
• Gas gangrene (clostridial myonecrosis) • Mixed infection • Toxigenic & proteolytic clostridia • Various cocci & gram negative bacteria
CLINICAL FINDINGS (Gas Gangrene)
• Spreads in 1-3 days • Crepitation & subcutaneous tissues & muscles • Foul smelling discharge • Necrosis, fever • Toxemia → shock → DEATH
CLINICAL FINDINGS (food poisoning)
• Enterotoxin forms in GUT • Diarrhea without vomiting or fever in 6-18 hours • Resolves in 1-2 days
DIAGNOSIS
• Clinical • Laboratory
• Culture • Chopped meat • Growth + gas • BAP • Target or double zone of hemolysis
DISEASES
• Gas gangrene (myonecrosis) • Anaerobic cellulitis • Food poisoning (alpha toxin) • Necrotic enteritis (fire in the bowel)
Prepared by: EGBII; 8-13-11
• Clostridial endometritis
TREATMENT
• Surgical debridement: most important • Antibiotics: Penicillin • Food poisoning: supportive
4. Clostridium difficile PSEUDOMEMBRANOUS COLITIS
• Drug resistant C. difficile produce toxins • Toxin A: enterotoxin • Toxin B: cytotoxin
• Pseudomembranes/ microabscesses in bowels • Watery/ bloody diarrhea • Clindamycin, Cephalosporins, Amoxicillin, Ampicillin
TREATMENT
• Discontinue offending antibiotic • Metronidazole or vancomycin
ANTIBIOTIC-ASSOCIATED DIARRHEA
• Administration of antibiotics leads to mild to moderate diarrhea
• Less severe than pseudomembranous colitis • 25% associated with C. difficile
DIAGNOSIS
• Toxins (stools) • Endoscopic exam
Non-Spore Forming
Gram Positive Bacilli Listeria Erysipelothrix Actinomycetes
1. Listeria monocytogenes • Gram positive • Short rod • Catalase positive • Beta hemolysis on BA • Tumbling motility at 22 – 28
oC
• Diffrentiates from diptheroids • Widespread of disease in human & animals • Important food-borne pathogen
• Survive in refrigerator temperature (4oC)
• Survive low pH • Survive high salt conditions • Overcome food preservation and safety barriers
• Antigenic Classifications • 1/2a • 1/2b • 4b: causes most food-borne outbreaks
PATHOGENESIS
• Ami, Fbp A, Flagellin protein • Bind to host cells & virulence • Internalin A
• Interacts with E-cadherin: cell well protein in epithelial cells
• Promote phagocytosis • Listeriolysin O: enzyme
• Lyses membrane, bacteria escape to cytoplasm
• Act A: surface protein • Induces host cell actin polymerization • Propels bacteria to cell membrane • Cause formation of Filipods
• Filipods • Ingested by epithelial cells,
macrophages & hepatocytes • Lifecycle begins abain
RESERVOIR
• Widespread: animals (gastrointestinal and genital tracts), • Unpasteurized milk products • Plants and soil • Cold growth: soft cheeses, deli meats, cabbages
(coleslaw)
PERINATAL HUMAN LISTERIOSIS
• Early onset syndrome • Granulomatosis infantseptica • Infection in utero • Neonatal sepsis, pustular & granulomas • Death; before / after delivery
• Late onset syndrome • Meningitis: birth to 3
rd week of life
• Caused by serotype 4b • High mortality rate
ADULTS
• Listeria meningoencephalitis • Immunocompromised • Insidious to fulminant
• Bacteremia
• Focal infections
TREATMENT
• Ampicillin, Erythromycin, IV Trimethoprom-sulfamethoxazole
• Ampicillin + Gentamycin – recommended
PREVENTION
• Precautions with food may reduce incidence
2. Erysipelothrix rhusopathiae Distinguishing Characteristics:
• Gram positive bacilli, non-branching • Catalase (-), Oxidase (-), Indole (-) • Alpha hemolysis on BA • Produced H2S on TSI (Butt Black)
• Differentiated from L. monocytogenes • Distributed in land & sea animals • Transmitted by direct inoculation • Greatest risk: fishermen, fish handlers, butchers, those in
contact with animal products ERYSIPELOID/ SEA FINGER/ WHALE FINGER
• Icubation Period: 2-7 days • Raised lesion w/ violaceous color • Pain & swelling • No pus
TREATMENT
• Penicillin G
3. Actinomycetes • Aerobic • Large diverse group of gram positive bacteria • Form chains or filaments • Categories:
• Acid fast positive: Mycobacteria • Weakly positive: Nocardia & Rhodococcus • Acid fast negative: Streptomyces
&Actinimadura
4. Nocardia Human infection: N. nova complex
• N. farcinica • N. asteroides type IV • N. brasiliensis
Prepared by: EGBII; 8-13-11
DISTINGUISHING CHARACTERISTICS
• Aerobic • Gram-positive branching rods • Catalase positive • Partially acid-fast • Produce urease • Can digest paraffin
• Inhalation of bacteria
• Not transmitted from person to person • Opportunistic infection
• Corticosteroid treatment, immunosuppression, organ transplantation, AIDS, TB
• Begins with lobar pneumonia • Mimic TB • Granulona & caseation are rare
• Abscess formation: usual pathologic process • Spread to CNS, skin, kidney & eyes
TREATMENT
• Trimethoprim-Sulfamethoxazole • Treatment of choice
• Amikacin, imipenem, minocycline, linezolide & ceftaxime • Surgical drainage
Actinomycetoma - mycetomal disease affecting the skin and connective tissue Mycetoma (Madura Foot)
• Most Common cause: • N. asteroides, N. brasiliensis, Streptomyces
somaliensis & Actinomadura madurae • Localized, slowly progressive chronic infection • Begins in subcutaneous tissues & spreads to adjacent
tissues • Destructive & painless
ANAEROBE BACTERIOLOGY
Definition of Terms
Aerobic Bacteria – require oxygen, and will not grow in the absence of oxygen
Anaerobic Bacteria – do not use oxygen for growth & metabolism but obtain their energy from fermentation
reactions
Capnophilic Bacteria – require CO2 for growth
Facultative Anaerobes – can grow either oxidatively or use fermentation reactions to obtain energy
FACTORS THAT INHIBIT GROWTH OF ANAEROBES BY OXYGEN
• Toxic compounds are produced • e.g. H2O2 , Superoxides
• Absence of catalase & superoxide dismutase • Oxidation of essential sulfhydyl groups in enzymes without
sufficient reducing power to regenerate them
ANAEROBIC BACTERIA OF CLINICAL IMPORTANCE
Bacilli Gram-negative
• Bacteriodes fragilis • Prevotella
melaninogenica • Fusobacterium
Gram-positive • Actinomyces • Lactobacillus • Clostridium
Cocci Gram-positive
• Peptostreptococcus • Peptococcus
Gram-negative • Veilonella
PATHOGENESIS OF ANAEROBIC INFECTIONS
• Polysaccharide capsule • Ability to induce abscess formation
• Lipopolysaccharide • Endotoxin: lack lipopolysaccaride structures with
endotoxic activity • Not directly produce clinical signs of sepsis
• Enzymes • Proteases, Neuraminidases, Cyclolysins • Cause hemolysis of erythrocytes • Damage and destroys tissues
• Superoxide dismutase (some bacteria) • Can survive in the presence of oxygen for days
DIAGNOSIS OF ANAEROBIC INFECTIONS
• Foul-smelling discharge (pus) • Short-chain fatty acid products of anaerobic
metabolism • Infection in proximity to a mucosal surface
• Anaerobes are part of normal flora • Gas in tissues
• Production of CO2 and H2 • Negative aerobic cultures
• Involve mixture of organisms • Form closed spaced infections or burrowing through tissues
(Lungs, brain, pleura, pelvis) • Most are susceptible to penicillin G
• Except: Bacteroides, some Prevotella species • Favored by reduce blood supply, necrotic tissues, low Eh
• Interfere with delivery of antibiotics • Uses special collection methods & transport media
METHODS USED TO PRODUCE ANAEROBIOSIS
• Gas Pak Jar, Brewer Jar, Torbal Jar • Cooked meat medium / Chopped cooked meat medium
sealed with petrolatum
• Anaerobic glove box & chamber PRAS Medium
• Pre-Reduced Anaerobically Sterilized medium
• e.g. Roll Tube of Hungate
• Thioglycollate medium • Aerobic • Anaerobic • Microaerophilic
• Resazurin Kanamycin-Vancomycin-Colistin (KVC) test
• Antibiotic Disks for the Presumptive Identification of Anaerobes
KVC PATTERN
• RRR- B. fragilis • SRS
• Fusobacterium • B. ureolyticus • Veillonella
• SSR- Clostridium, gram (+) cocci • RSR- Porphyromonas, P. anaerobius • RRS- Prevotella
RESPIRATORY TRACT
• Prevotella melaninogenica, Fusobacterium &
Peptostreptoccocus • Periodeontal infections, perioral abscess, sinusitis,
mastoiditis • Saliva aspiration: necrotizing pneumonia, lung
abscess & empyema CENTRAL NERVOUS SYSTEM
• Brain abscess, subdural empyema, septic thrombophlebitis • Originate from respiratory tract, spread hematogenously
INTRA-ABDOMINAL & PELVIC INFECTIONS
• Flora of colon: B. fragilis, Clostridia, Peptostreptococcus
• Infection due to perforated bowel • Prevotella originate from female genital organs
SKIN & SOFT TISSUES
• Anaerobes & aerobes: synergistic infections • Gangrene, necrotizing fasciitis, cellulitis
Anaerobic Infections
TREATMENT • Surgical drainage: most important • Antimicrobial Therapy
• Penicillin G • Clindamycin
Prepared by: EGBII; 8-13-11
• Preferred for infections above diaphragm • Metronidazole
Prepared by: EGBII; 8-13-11
Spore-Forming Gram Positive Bacilli Bacilli species - aerobic Clostridium species – non aerobic
A. Bacilli species – Spore forming bacilli
• Large aerobic, gram positive rods in chains • Most are saprophylic
• Most do not cause disease • Important diseases: Anthrax, Food
Poisoning
• Spores located in center • Non-motile • “Cut glass” appearance in culture
• Use nitrogen & carbon for energy • Spores are resistant to environmental
changes, dry heat, certain disinfectants
1. Bacillus anthracis
• Anthrax: primarily disease of herbivores • Humans are infected incidentally
• Acquired by the entry of spores • Injured skin (cutaneous anthrax) • Mucous membrane
(gastrointestinal anthrax) • Inhalation (inhalation anthrax)
PATHOLOGY
• Spores germinate in tissues at the site of
entry • Formation of edema & congestion • Spread via lymphatics
• Three Anthrax toxin • Protective antigen (PA) • Edema factor (EF)
• Lethal factor (LF) • PA binds to specific cell receptors:
entry of EF & LF
• EF + PA = edema toxin • LF + PA = lethal toxin (virulence
factor)
CLINICAL FINDINGS
• Humans: 95% (cutaneous), 5% (inhalation) • Cutaneous anthrax
• 1-7 days: pruritic rash
• Papule → vesicle → necrotic ulcer
• Lesion has central black eschar
• Edema, lymphangitis, lymphadenopathy
• Healing by granulation & leaves
a scar • Incubation period: 6 weeks • Inhalation (Wool sorter’s disease)
• Hemorrhagic necrosis & edema of mediastinum
• Pleural effusion
• Sepsis • GI: bowel ulceration
• Brain: hemorrhagic menigitis
DIAGNOSTICS
• Specimem: fluid from local lesion, blood & sputum
• Chains of large gram positive rods • Blood agar: non-hemolytic gray to white
colonies, with comma shaped outgrowths (Medusa head)
TREATMENT
• Ciprofloxacin: recommended • Penicillin G, Gentamycin, Streptomycin
PREVENTION
• Proper disposal of animal carcasses • Decontamination of animal products • Protective handling of potentially infected
materials • Active immunization of domestic animals
2. Bacillus cereus • Produce toxins that cause disease
• Spores germinate, vegetative
cells produce toxins
CLINICAL FINDINGS
• Emetic type (rice) • Nausea, vomiting, abdominal
cramps • Self limiting
• Diarrheal type (meat dishes & sauces)
• Diarrhea w/ abdominal pain & cramps
• Enterotoxin : pre-formed or
produced in the intestine • Eye infections
• Organisms are introduced by
foreign bodies • Local & systemic infections
• Endocarditis, meningitis,
osteomyelitis • Presence of medical device (IV
lines) & IV drugs • Presence of B. cereus in stool is not
diagnostic • 10
5 bacteria or more per gram of food is
diagnostic • Culture: exhibit motility “swarming”
TREATMENT
• Drug of choice: vancomycin or clindamycin
• Resistant to penicillins & cephalosporins
B. Clostridium Species
Clostridium botulinium Clostridium tetani
Clostridium perfringens Clostridium difficile
Clostridium Species • Large, anaerobic, gram (+), motile rods • Decompose proteins or form toxins or both
• Spore is place centrally, sub-terminally or terminally
• Produce large raised colonies (C.
perfringens) • Small colonies (C. tetani) • Many produce hemolysis on blood agar (C.
perfringens: double zone)
• Ferment a variety of sugars • Many digest proteins
1. Clostridium botulinium CHARACTERISTICS
• Causes Botulism • Found in soil • Produce toxins:
• Type A, B, E, occasionally F: human illness
• Among the most toxic
substances • Destroyed by heating for 20
mins at 100⁰C
PATHOGENESIS
• Illness is not infection
• INTOXICATION • Toxins acts by blocking the release of
acetylcholine at synapses &
neuromuscular junctions • FLACCID PARALYSIS
CLINICAL FINDINGS
• Visual disturbances
• Dysphagia • Speech difficulty • Signs of bulbar paralysis
• Cause of death: respiratory paralysis or cardiac arrest
TREATMENT
• Antitoxins (A, B and E)
• Supportive • Ventilation
2. Clostridium tetani • Characteristics
• Gram (+) bacilli, terminal spores • Obligate anaerobes, motile
• Reservoir
• Soil/ feces of animals • Transmission
• Puncture wounds/trauma
• Requires low tissue oxygenation (Eh)
• LOCALIZED
PATHOGENESIS
• Spores germinate in the tissues: tetanospasmin
• A fragment: blocks NT release at inhibitory synapses
• B fragment: mediates binding to
neuron and cell penetration of A fragment
• Carried intra-axonally to CNS
• Binds to ganglioside receptors • Blocks release of inhibitory mediators
(glycine and GABA) at spinal synapses
• Excitatory neurons are unopposed → extreme muscle spasm
CLINICAL FINDINGS
• Incubation period: 4 – 5 days (up to weeks)
• Tonic contraction of voluntary muscles • Spasm first in area of injury, then the
muscles of the jaw
• External stimuli may precipitate muscle spasm
• Death: spasm of respiratory muscles
Prepared by: EGBII; 8-13-11
TETANUS
• Trismus, risus sardonicus, opisthotonus
DIAGNOSIS: Clinical *
TREATMENT
• Hyperimmune human globulin (TIG) to neutralize toxin
• + Metronidazole or Penicillin
• Spasmolytic drugs (diazepam), debride, delay course
PREVENTION
• DTP, DTaP, Td • TIG • Proper wound care
Wound Management
3. Clostridium perfringens CHARACTERISTICS
• Encapsulated • Non motile • Double hemolysis
• Ferment CHO • Reservoir: Soil and human colon • INVASIVE
TOXINS
• Alpha toxin (Lecithinase) • Necrotizing & hemolytic effect
• Theta toxin
• Necrotizing & hemolytic effect • DNase & Hyaluronidaes
• Digest collagen
• Enterotoxin
• Alters cell membrane, disrupting ion transport
PATHOGENESIS
• Spores germinate under anaerobic conditions in tissues
• Distention of tissues &interference of blood
supply, presence of toxins • Spread of infection • Tissue necrosis
• Hemolytic anemia • Severe toxemia
• Gas gangrene (clostridial myonecrosis)
• Mixed infection • Toxigenic & proteolytic clostridia • Various cocci & gram negative
bacteria
CLINICAL FINDINGS (Gas Gangrene)
• Spreads in 1-3 days • Crepitation & subcutaneous tissues &
muscles • Foul smelling discharge • Necrosis, fever
• Toxemia → shock → DEATH
CLINICAL FINDINGS (food poisoning)
• Enterotoxin forms in GUT • Diarrhea without vomiting or fever in 6-18
hours • Resolves in 1-2 days
DIAGNOSIS
• Clinical
• Laboratory • Culture • Chopped meat
• Growth + gas • BAP • Target or double zone of
hemolysis
DISEASES
• Gas gangrene (myonecrosis) • Anaerobic cellulitis
• Food poisoning (alpha toxin) • Necrotic enteritis (fire in the bowel) • Clostridial endometritis
TREATMENT
• Surgical debridement: most important • Antibiotics: Penicillin
• Food poisoning: supportive
4. Clostridium difficile PSEUDOMEMBRANOUS COLITIS
• Drug resistant C. difficile produce toxins
• Toxin A: enterotoxin • Toxin B: cytotoxin
• Pseudomembranes/ microabscesses in bowels
• Watery/ bloody diarrhea • Clindamycin, Cephalosporins, Amoxicillin,
Ampicillin
TREATMENT
• Discontinue offending antibiotic • Metronidazole or vancomycin
ANTIBIOTIC-ASSOCIATED DIARRHEA
• Administration of antibiotics leads to mild to moderate diarrhea
• Less severe than pseudomembranous colitis
• 25% associated with C. difficile
DIAGNOSIS
• Toxins (stools) • Endoscopic exam
Non-Spore Forming Gram Positive Bacilli
Listeria Erysipelothrix Actinomycetes
1. Listeria monocytogenes • Gram positive • Short rod • Catalase positive
• Beta hemolysis on BA • Tumbling motility at 22 – 28
oC
• Diffrentiates from diptheroids
• Widespread of disease in human & animals
• Important food-borne pathogen
• Survive in refrigerator temperature (4
oC)
• Survive low pH
• Survive high salt conditions • Overcome food preservation and
safety barriers
• Antigenic Classifications • 1/2a • 1/2b
• 4b: causes most food-borne outbreaks
PATHOGENESIS
• Ami, Fbp A, Flagellin protein
• Bind to host cells & virulence • Internalin A
• Interacts with E-
cadherin: cell well
protein in epithelial cells
• Promote phagocytosis • Listeriolysin O: enzyme
• Lyses membrane,
bacteria escape to cytoplasm
• Act A: surface protein
• Induces host cell actin polymerization
• Propels bacteria to cell
membrane • Cause formation of
Filipods
• Filipods • Ingested by epithelial
cells, macrophages &
hepatocytes • Lifecycle begins abain
RESERVOIR
• Widespread: animals (gastrointestinal and
genital tracts), • Unpasteurized milk products • Plants and soil
• Cold growth: soft cheeses, deli meats, cabbages (coleslaw)
PERINATAL HUMAN LISTERIOSIS
• Early onset syndrome
• Granulomatosis infantseptica • Infection in utero • Neonatal sepsis, pustular &
granulomas • Death; before / after delivery
• Late onset syndrome
• Meningitis: birth to 3rd
week of life
• Caused by serotype 4b
• High mortality rate
ADULTS
• Listeria meningoencephalitis • Immunocompromised
• Insidious to fulminant • Bacteremia • Focal infections
TREATMENT
• Ampicillin, Erythromycin, IV Trimethoprom-sulfamethoxazole
• Ampicillin + Gentamycin – recommended
PREVENTION
• Precautions with food may reduce
incidence
Prepared by: EGBII; 8-13-11
2. Erysipelothrix rhusopathiae Distinguishing Characteristics:
• Gram positive bacilli, non-branching • Catalase (-), Oxidase (-), Indole (-)
• Alpha hemolysis on BA • Produced H2S on TSI (Butt Black)
• Differentiated from L.
monocytogenes
• Distributed in land & sea animals • Transmitted by direct inoculation
• Greatest risk: fishermen, fish handlers, butchers, those in contact with animal products
ERYSIPELOID/ SEA FINGER/ WHALE FINGER
• Icubation Period: 2-7 days
• Raised lesion w/ violaceous color • Pain & swelling • No pus
TREATMENT
• Penicillin G
3. Actinomycetes • Aerobic • Large diverse group of gram positive
bacteria
• Form chains or filaments • Categories:
• Acid fast positive: Mycobacteria
• Weakly positive: Nocardia & Rhodococcus
• Acid fast negative: Streptomyces
&Actinimadura
4. Nocardia Human infection: N. nova complex
• N. farcinica • N. asteroides type IV • N. brasiliensis
DISTINGUISHING CHARACTERISTICS
• Aerobic • Gram-positive branching rods
• Catalase positive • Partially acid-fast • Produce urease
• Can digest paraffin
• Inhalation of bacteria
• Not transmitted from person to person
• Opportunistic infection • Corticosteroid treatment,
immunosuppression, organ transplantation, AIDS, TB
• Begins with lobar pneumonia
• Mimic TB • Granulona & caseation are rare
• Abscess formation: usual pathologic
process • Spread to CNS, skin, kidney & eyes
TREATMENT
• Trimethoprim-Sulfamethoxazole • Treatment of choice
• Amikacin, imipenem, minocycline,
linezolide & ceftaxime • Surgical drainage
Actinomycetoma - mycetomal disease affecting the skin and connective tissue Mycetoma (Madura Foot)
• Most Common cause: • N. asteroides, N. brasiliensis,
Streptomyces somaliensis &
Actinomadura madurae
• Localized, slowly progressive chronic infection
• Begins in subcutaneous tissues & spreads to adjacent tissues
• Destructive & painless
ANAEROBE
BACTERIOLOGY
Definition of Terms
Aerobic Bacteria – require oxygen, and will not grow in the absence of oxygen
Anaerobic Bacteria – do not use oxygen for growth & metabolism but obtain their energy from fermentation
reactions
Capnophilic Bacteria – require CO2 for
growth
Facultative Anaerobes – can grow either oxidatively or use fermentation reactions to obtain energy
FACTORS THAT INHIBIT GROWTH OF ANAEROBES BY OXYGEN
• Toxic compounds are produced • e.g. H2O2 , Superoxides
• Absence of catalase & superoxide dismutase
• Oxidation of essential sulfhydyl groups in enzymes without sufficient reducing power to regenerate them
ANAEROBIC BACTERIA OF CLINICAL IMPORTANCE
Bacilli Gram-negative
• Bacteriodes
fragilis • Prevotella
melaninogenica • Fusobacterium
Gram-positive • Actinomyces • Lactobacillus • Clostridium
Cocci Gram-positive
• Peptostrept
ococcus • Peptococc
us Gram-negative
• Veilonella
PATHOGENESIS OF ANAEROBIC INFECTIONS
• Polysaccharide capsule
• Ability to induce abscess formation
• Lipopolysaccharide • Endotoxin: lack
lipopolysaccaride structures with endotoxic activity
• Not directly produce clinical signs of sepsis
• Enzymes • Proteases, Neuraminidases,
Cyclolysins • Cause hemolysis of
erythrocytes • Damage and destroys tissues
• Superoxide dismutase (some bacteria) • Can survive in the presence of
oxygen for days DIAGNOSIS OF ANAEROBIC INFECTIONS
• Foul-smelling discharge (pus) • Short-chain fatty acid products
of anaerobic metabolism • Infection in proximity to a mucosal
surface • Anaerobes are part of normal
flora • Gas in tissues
• Production of CO2 and H2 • Negative aerobic cultures • Involve mixture of organisms
• Form closed spaced infections or burrowing through tissues (Lungs, brain, pleura, pelvis)
• Most are susceptible to penicillin G • Except: Bacteroides, some
Prevotella species • Favored by reduce blood supply,
necrotic tissues, low Eh • Interfere with delivery of
antibiotics • Uses special collection methods &
transport media METHODS USED TO PRODUCE ANAEROBIOSIS
• Gas Pak Jar, Brewer Jar, Torbal Jar • Cooked meat medium / Chopped
cooked meat medium sealed with petrolatum
• Anaerobic glove box & chamber PRAS Medium
• Pre-Reduced Anaerobically Sterilized medium
• e.g. Roll Tube of Hungate
• Thioglycollate medium • Aerobic
• Anaerobic • Microaerophilic • Resazurin
Kanamycin-Vancomycin-Colistin (KVC) test
• Antibiotic Disks for the Presumptive Identification of Anaerobes
KVC PATTERN
• RRR- B. fragilis • SRS
• Fusobacterium
• B. ureolyticus • Veillonella
• SSR- Clostridium, gram (+) cocci • RSR- Porphyromonas, P. anaerobius • RRS- Prevotella
RESPIRATORY TRACT • Prevotella melaninogenica,
Fusobacterium & Peptostreptoccocus • Periodeontal infections,
perioral abscess, sinusitis, mastoiditis
Prepared by: EGBII; 8-13-11
• Saliva aspiration: necrotizing pneumonia, lung abscess & empyema
CENTRAL NERVOUS SYSTEM
• Brain abscess, subdural empyema, septic thrombophlebitis
• Originate from respiratory tract, spread hematogenously
INTRA-ABDOMINAL & PELVIC INFECTIONS
• Flora of colon: B. fragilis, Clostridia,
Peptostreptococcus • Infection due to perforated bowel • Prevotella originate from female genital
organs SKIN & SOFT TISSUES
• Anaerobes & aerobes: synergistic infections
• Gangrene, necrotizing fasciitis, cellulitis Anaerobic Infections
TREATMENT • Surgical drainage: most important • Antimicrobial Therapy
• Penicillin G • Clindamycin
• Preferred for
infections above diaphragm
• Metronidazole
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