Sporeforming & Non-Spore Forming Bacteria

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


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)


• 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


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


• Preferred for infections above diaphragm • Metronidazole


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


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


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


• 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

Documents

Sporeforming & Non-Spore Forming Bacteria