chapter 19 the gram-positive bacilli of medical importance
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Chapter 19
The Gram-Positive Bacilli of Medical The Gram-Positive Bacilli of Medical ImportanceImportance
Medically Important Gram-Positive Bacilli
The gram-positive The gram-positive bacilli include about a bacilli include about a dozen genera of dozen genera of medically significant medically significant bacteriabacteria
They are differentiated They are differentiated on the basis of on the basis of endospores, acid-endospores, acid-fastness, and cell fastness, and cell morphologymorphology
Aerobic, Sporogenous Gram Positive Rods
Bacillus anthracisBacillus anthracis is the most prominent is the most prominent member of the genus member of the genus
Causative agent of antrax, a zoonosis that Causative agent of antrax, a zoonosis that exists in both cutaneous and pulmonary exists in both cutaneous and pulmonary formsforms
Clinical significance - B. anthracis = anthrax (seen primarily in cattle)
Human infections follow exposure to infected animals or Human infections follow exposure to infected animals or animal products - spores reside in soil & on plantsanimal products - spores reside in soil & on plants
Forms in humansForms in humans Pulmonary - follows inhalation of spores; usually observed Pulmonary - follows inhalation of spores; usually observed
in workers in woolen mills (woolsorter’s disease)in workers in woolen mills (woolsorter’s disease) Cutaneous = malignant pustule - follows cutaneous Cutaneous = malignant pustule - follows cutaneous
inoculation of spores; lesion is small initially but enlarges inoculation of spores; lesion is small initially but enlarges with formation of black eschar; self-limitingwith formation of black eschar; self-limiting
Gastrointestinal = follows ingestion of contaminated food; Gastrointestinal = follows ingestion of contaminated food; begins with nausea, abdominal pain & vomiting followed begins with nausea, abdominal pain & vomiting followed by bloody diarrhea, toxemia & shockby bloody diarrhea, toxemia & shock
Septicemia - may follow any formSepticemia - may follow any form
Cutaneous antrax
Epidemiology
Habitat - spores in soil & on plantsHabitat - spores in soil & on plants Routes of transmission - aerosols, direct Routes of transmission - aerosols, direct
contact, ingestioncontact, ingestion Prevention & control - difficult; vaccine for Prevention & control - difficult; vaccine for
susceptible individualssusceptible individuals Treatment - penicillinTreatment - penicillin
Anaerobic, Sporogenous Gram Positive Rods
ClostridiumClostridium C. tetaniC. tetani C. botulinumC. botulinum C. perfringensC. perfringens & other gas-producing & other gas-producing
clostridiaclostridia C. difficileC. difficile
General characteristics Gram positive, spore-forming rods - some are easily Gram positive, spore-forming rods - some are easily
decolorized; cells are usually large; should be suspected if decolorized; cells are usually large; should be suspected if large cells (either gram + or -) seen in Gram stainslarge cells (either gram + or -) seen in Gram stains
Virulence factorsVirulence factors Toxins Toxins
Neurotoxins of Neurotoxins of C. botulinum & C. tetaniC. botulinum & C. tetani Lethal toxins of Lethal toxins of C. perfringensC. perfringens - especially alpha toxin; - especially alpha toxin;
actually a lecithinaseactually a lecithinase Enterotoxin of Enterotoxin of C. perfringens & C. difficileC. perfringens & C. difficile
Enzymes - numerous including hyaluronidase, Enzymes - numerous including hyaluronidase, collagenase, proteases, RNAse, DNAse, lecithinasecollagenase, proteases, RNAse, DNAse, lecithinase
Clinical manifestations: C. tetani - tetanus (lockjaw)
Toxic disease associated with 2 toxins – Toxic disease associated with 2 toxins – tetanospasmintetanospasmin (neurotoxin) & tetanolysin (neurotoxin) & tetanolysin (hemolytic toxin)(hemolytic toxin)
Spores of organism found in feces of humans & Spores of organism found in feces of humans & variousvarious animals; found in soil, dust - survive for animals; found in soil, dust - survive for yearsyears
Incubation period = 1-54 daysIncubation period = 1-54 days Signs & symptoms = cramps & twitching in muscles Signs & symptoms = cramps & twitching in muscles
around wound, irritability, tachycardia & anxious around wound, irritability, tachycardia & anxious facialfacial expressions later progressing to lockjaw, expressions later progressing to lockjaw, spasms of the jaw and finally spasticity of neck, spasms of the jaw and finally spasticity of neck, trunk & limbstrunk & limbs
Clinical manifestations: C. tetani - tetanus (lockjaw)
Spores enter body through wound contaminated with soilSpores enter body through wound contaminated with soil or feces - require or feces - require relative deep wound to provide anaerobicrelative deep wound to provide anaerobic conditions for sporulation & toxin conditions for sporulation & toxin formulation formulation
Toxin reaches CNS through blood, lymph or travelingToxin reaches CNS through blood, lymph or traveling through tissue spaces through tissue spaces of peripheral nervesof peripheral nerves
Neurotoxin blocks neurotransmitter release preventing muscle contraction Neurotoxin blocks neurotransmitter release preventing muscle contraction when the opposing muscle contractswhen the opposing muscle contracts causing uncontrolled contraction of causing uncontrolled contraction of musclemuscle
Clinical manifestations: C. botulinum - botulism
Toxic disease associated with a Toxic disease associated with a neurotoxin - divides organisms into neurotoxin - divides organisms into serogroups based on antigenic type ofserogroups based on antigenic type of toxintoxin Botulinum toxin is most powerful Botulinum toxin is most powerful
toxin knowntoxin known Acts on neuromuscular junctions Acts on neuromuscular junctions
of peripheralof peripheral nervous system nervous system blocking release of nerve impulseblocking release of nerve impulse causing a “flaccid (floppy)” causing a “flaccid (floppy)” paralysisparalysis
Recovery of nerve function occurs Recovery of nerve function occurs only when newonly when new toxin-free nerve toxin-free nerve endings regeneratedendings regenerated
Antitoxin has no effect on bound Antitoxin has no effect on bound only free toxinonly free toxin
Clinical manifestations: C. botulinum - botulism
Foodborne botulismFoodborne botulism Follows ingestion of preformed toxinFollows ingestion of preformed toxin Foods most commonly involved = vegetables or Foods most commonly involved = vegetables or
condiments prepared from vegetables & fish (inadequately condiments prepared from vegetables & fish (inadequately processed home-canned food is mostprocessed home-canned food is most common source in common source in US)US)
Nausea, vomitting & diarrhea are first clinical signs - Nausea, vomitting & diarrhea are first clinical signs - neurologic symptoms usually appear 18-36neurologic symptoms usually appear 18-36 hours after hours after consumption of contaminated foodconsumption of contaminated food characterized by characterized by descending paralysis that beginsdescending paralysis that begins with ocular muscles with ocular muscles (diplopia) rapidly progressing to pharyngeal muscles (diplopia) rapidly progressing to pharyngeal muscles (dysphagia, hoarseness) & muscles of neck, trunk & limbs(dysphagia, hoarseness) & muscles of neck, trunk & limbs
Death occurs through paralysis of respiratory musclesDeath occurs through paralysis of respiratory muscles
Clinical manifestations: C. botulinum - botulism
Infant botulismInfant botulism Follows ingestion of spores which germinate in Follows ingestion of spores which germinate in
intestine & produce toxin in intestineintestine & produce toxin in intestine Foods most commonly involved - honeyFoods most commonly involved - honey Only infants under 1 year are affected - no stable Only infants under 1 year are affected - no stable
gut flora to inhibit germination of ingested sporesgut flora to inhibit germination of ingested spores Symptoms range from subclinical to deathSymptoms range from subclinical to death
Clinical manifestations: C. botulinum - botulism
Wound botulismWound botulism Follows contamination of a traumatic Follows contamination of a traumatic
wound with organism or as complication of wound with organism or as complication of chronic drug abusechronic drug abuse
Toxin released, absorbed & travels via Toxin released, absorbed & travels via lymph & blood to nerve terminalslymph & blood to nerve terminals
Symptoms similar to foodborne botulismSymptoms similar to foodborne botulism
C. perfringens & other gas-producing clostridia
Anaerobic cellulitisAnaerobic cellulitis Follows invasion of Follows invasion of
necrotic wound by necrotic wound by proteolytic clostridiaproteolytic clostridia
Characterized by gas Characterized by gas accumulation, accumulation, discoloration of discoloration of underlying skin and underlying skin and presence of malodorous, presence of malodorous, brownish, purulent brownish, purulent dischargedischarge
C. perfringens & other gas-producing clostridia
Myonecrosis (gas gangrene)Myonecrosis (gas gangrene) Involves invasion of normal healthy muscle surrounding Involves invasion of normal healthy muscle surrounding
traumatic woundtraumatic wound Associated with deep wounds (e.g. warfare) containing Associated with deep wounds (e.g. warfare) containing
foreign bodies, having blocked blood supplies and/or foreign bodies, having blocked blood supplies and/or presence of necrotic tissuepresence of necrotic tissue
Symptoms include drowsiness, fever, tachycardia & a Symptoms include drowsiness, fever, tachycardia & a painful edematous wound with a sweet or foul-smelling painful edematous wound with a sweet or foul-smelling discharge - gas is present but not as obvious as in cellulitis discharge - gas is present but not as obvious as in cellulitis - may be fatal- may be fatal
C. perfringensC. perfringens most common clostridial species involved most common clostridial species involved
C. difficile
Associated with 90-100% Associated with 90-100% of pseudomembranous of pseudomembranous enterocolitis following enterocolitis following antimicrobial therapy antimicrobial therapy especially following especially following clindamycin, clindamycin, cephalosporins & cephalosporins & ampicillinampicillin
C. difficile
Components of disease - disturbance of normal Components of disease - disturbance of normal bowel flora by antimicrobial agents, a source of bowel flora by antimicrobial agents, a source of C. C. difficiledifficile (endogenous or exogenous) & organism (endogenous or exogenous) & organism must have potential for producing toxinmust have potential for producing toxin
Sources of Sources of C. difficileC. difficile = hospital environment & = hospital environment & endogenous (normal intestinal flora of 3% healthy endogenous (normal intestinal flora of 3% healthy adults and 10-20% hospitalized patients)adults and 10-20% hospitalized patients)
Associated with two toxins - toxin A = enterotoxin Associated with two toxins - toxin A = enterotoxin causing diarrhea & toxin B = cytotoxin causing causing diarrhea & toxin B = cytotoxin causing cellular damagecellular damage
Epidemiology
HabitatHabitat Intestinal flora (Intestinal flora (C. perfringens, C. tetani C. perfringens, C. tetani
& C. difficile& C. difficile)) Environment - soil & animalsEnvironment - soil & animals
Routes of transmissionRoutes of transmission Traumatic woundsTraumatic wounds IngestionIngestion EndogenousEndogenous
Epidemiology
Prevention & ControlPrevention & Control Vaccine - tetanus toxoid (DPT)Vaccine - tetanus toxoid (DPT) Properly canning foodsProperly canning foods Avoid giving honey to child under 1 year (Avoid giving honey to child under 1 year (C. C.
botulinumbotulinum)) TreatmentTreatment
Tetanus & botulism - specific antitoxinTetanus & botulism - specific antitoxin Debridement of woundDebridement of wound Supportive therapy (respiratory assist)Supportive therapy (respiratory assist) Antibiotic therapy (antibiogram)Antibiotic therapy (antibiogram)
Gram-Positive Regular Non-Spore-Forming Bacilli
Non-spore-forming rods are divided among Non-spore-forming rods are divided among those that have regular and irregular shapes those that have regular and irregular shapes and staining propertiesand staining properties
Straight, nonpleomorphic rods stain evenly Straight, nonpleomorphic rods stain evenly and include the genera and include the genera ListeriaListeria and and ErysipelothrixErysipelothrix
Listeria Species of medical importance - Species of medical importance - L. L.
monocytogenesmonocytogenes; only species pathogenic for man; only species pathogenic for man Clinical manifestations - restricted to several Clinical manifestations - restricted to several
defined populationsdefined populations NeonatesNeonates
Early onset - acquired in utero or during birthEarly onset - acquired in utero or during birthGranulomatosis infantiseptica - fetus often Granulomatosis infantiseptica - fetus often
stillborn; multiple granulomasstillborn; multiple granulomasMeningitis and sepsisMeningitis and sepsis
Late onset - begins 2-3 weeks after birth; Late onset - begins 2-3 weeks after birth; acquired from environment = meningitis and acquired from environment = meningitis and sepsissepsis
Listeria
Pregnant women - puerperal sepsis & bacteremiaPregnant women - puerperal sepsis & bacteremia Immunocompromised - particularly with Immunocompromised - particularly with
malignancies or renal transplantmalignancies or renal transplant Meningitis - common cause in renal transplantsMeningitis - common cause in renal transplants EndocarditisEndocarditis
Fatalities - greater in newborn under 4 weeks & Fatalities - greater in newborn under 4 weeks & adults over 50adults over 50
Epidemiology Natural habitat - primarily Natural habitat - primarily
zoonotic but also found in zoonotic but also found in soil, water, vegetation & soil, water, vegetation & intestine of humansintestine of humans
Routes of transmissionRoutes of transmission Ingestion - esp. milk Ingestion - esp. milk
products (not always products (not always killed by killed by pasteurization), meat & pasteurization), meat & cabbagecabbage
Direct - female to Direct - female to infants or with infants or with environmental sourceenvironmental source
Prevention and control - Prevention and control - difficult (organisms are difficult (organisms are ubiquitous)ubiquitous)
Treatment - penicillinTreatment - penicillin
Erysipelothrix
Species of medical importance - Species of medical importance - E. E. rhusiopathiaerhusiopathiae
Clinical manifestations Clinical manifestations Septicemia and endocarditisSepticemia and endocarditis
Uncommon but seen together when Uncommon but seen together when they occurthey occur
Most susceptible = persons with Most susceptible = persons with previously damaged heart valvespreviously damaged heart valves
Erysipelothrix ErysipeloidErysipeloid
Inflammatory Inflammatory condition of skin; condition of skin; usually fingers & usually fingers & hands; suppurationhands; suppuration
Lesions usually Lesions usually erythematous with erythematous with raised edge; spread raised edge; spread peripherallyperipherally
Spontaneous cure = Spontaneous cure = usualusual
Epidemiology
Natural habitat - ubiquitous; primarily zoonotic Natural habitat - ubiquitous; primarily zoonotic (mammals, birds, & fish); pigs = main source of (mammals, birds, & fish); pigs = main source of human infection; also in soil where infected human infection; also in soil where infected animals grazeanimals graze
Modes of transmission = trauma (enter via Modes of transmission = trauma (enter via abrasions); usually occupational (esp. butchers, abrasions); usually occupational (esp. butchers, meat processors, farmers, poultry workers, meat processors, farmers, poultry workers, fisherman, vets)fisherman, vets)
Prevention and control - protective clothing when Prevention and control - protective clothing when handling infected sourceshandling infected sources
Treatment - penicillinTreatment - penicillin
Gram-Positive Irregular Non-Spore-Forming Bacilli
CorynebacteriumCorynebacterium Species of medial Species of medial
importanceimportance C. diphtheriaeC. diphtheriae C. ulceransC. ulcerans C. pseudotuberculosisC. pseudotuberculosis Group JKGroup JK
Clinical manifestations - C. diphtheriae
DiphtheriaDiphtheria Incubation period = 2-4 daysIncubation period = 2-4 days Begins as pharyngitis (toxigenic Begins as pharyngitis (toxigenic
& non-toxigenic strains)& non-toxigenic strains) Only toxigenic strains produce Only toxigenic strains produce
pseudomembrane (toxin causes pseudomembrane (toxin causes membrane; contains fibrin, membrane; contains fibrin, WBC’s, cellular debris & bacteria WBC’s, cellular debris & bacteria - forms on pharynx but may - forms on pharynx but may extend into trachea); cervical extend into trachea); cervical adenitis common = bullneck adenitis common = bullneck appearanceappearance
Uncomplicated diphtheria = Uncomplicated diphtheria = resolves; membrane is coughed resolves; membrane is coughed upup
Clinical manifestations - C. diphtheriae
Complications and mortality caused by respiratory Complications and mortality caused by respiratory obstruction or systemic effects of toxinobstruction or systemic effects of toxin
Obstruction of airway due to membrane, edema & Obstruction of airway due to membrane, edema & hemorrhage; can lead to sudden & complete hemorrhage; can lead to sudden & complete suffocation - deathsuffocation - death
Toxin may cause myocarditis (cardiac Toxin may cause myocarditis (cardiac enlargement, weakness, arrhythmia & CHF) and enlargement, weakness, arrhythmia & CHF) and paralysis of peripheral & cranial nerves (affected paralysis of peripheral & cranial nerves (affected = soft palate, eyes & some muscles usually not = soft palate, eyes & some muscles usually not serious unless diaphragm involved)serious unless diaphragm involved)
Epidemiology Prevention and control - Prevention and control - C. diphtheriaeC. diphtheriae Immunization with vaccine containing toxoidImmunization with vaccine containing toxoid Schick test - uses intracutaneous injection of Schick test - uses intracutaneous injection of
toxin; detects immune statustoxin; detects immune status Positive reaction = local edema, necrosis & Positive reaction = local edema, necrosis &
desquamation = susceptible (no antitoxin)desquamation = susceptible (no antitoxin) Negative reaction = no reaction = immune Negative reaction = no reaction = immune
(toxin neutralized by circulating Ab = (toxin neutralized by circulating Ab = antitoxin)antitoxin)
Epidemiology TreatmentTreatment
Antitoxin (antiserum)Antitoxin (antiserum) Uses preformed Ab’s produced in horses or humans Uses preformed Ab’s produced in horses or humans
(hyperimmune IgG)(hyperimmune IgG) Must be administered early before toxin attaches to Must be administered early before toxin attaches to
target cellstarget cells Hypersensitivity & serum sickness may result from Hypersensitivity & serum sickness may result from
horse serum & complicate therapyhorse serum & complicate therapy Antibiotics - penicillins & erythromycinAntibiotics - penicillins & erythromycin Supportive therapy - removal of obstructions, minimize Supportive therapy - removal of obstructions, minimize
CHF, regulate respirationCHF, regulate respiration
Mycobacteria
General characteristicsGeneral characteristics Aerobic, non-sporogenous, non-motile rodsAerobic, non-sporogenous, non-motile rods Acid fast - cells resist acid decolorizationAcid fast - cells resist acid decolorization Possess high levels of mycolic acids and Possess high levels of mycolic acids and
other lipids in addition to peptidoglycan in other lipids in addition to peptidoglycan in their cell wallstheir cell walls
Slow growing (2 days - 6 weeks)Slow growing (2 days - 6 weeks) Highly resistant to disinfectant & Highly resistant to disinfectant &
sterilization proceduressterilization procedures
Clinical Manifestations
M. lepraeM. leprae - Hansen's disease - Hansen's disease Chronic infectious disease - over 200 new cases diagnosed Chronic infectious disease - over 200 new cases diagnosed
each year; approx. 13 million person infected world-wideeach year; approx. 13 million person infected world-wide Method of transmission from person-person unknown; Method of transmission from person-person unknown;
depends on a susceptible hostdepends on a susceptible host Children more susceptible than adults; males more than Children more susceptible than adults; males more than
femalesfemales Most persons probably cannot be infected by any meansMost persons probably cannot be infected by any means May be acquired through skin-skin contact or contact with May be acquired through skin-skin contact or contact with
nasal dischargenasal discharge
M. leprae - Hansen's disease
Presents clinically in either Presents clinically in either of two major forms - form is of two major forms - form is dependent on adequacy of dependent on adequacy of host's cell-mediated responsehost's cell-mediated response Tuberculoid leprosy - Tuberculoid leprosy -
usually self-limiting; may usually self-limiting; may regress spontaneously; regress spontaneously; single skin lesions and single skin lesions and nerve involvement nerve involvement producing patches of producing patches of anesthesia most common anesthesia most common feature (produced by feature (produced by inflammatory response to inflammatory response to organisms); organisms organisms); organisms are extremely rare in are extremely rare in tissuetissue
M. leprae - Hansen's disease
Lepromatous leprosy - Lepromatous leprosy - progressive & malignant; progressive & malignant; may be fatal; skin may be fatal; skin involvement extensive; involvement extensive; organisms found in every organisms found in every organ - major changes organ - major changes detected in skin, nerves & detected in skin, nerves & testes; lesions of skin & testes; lesions of skin & mm - hypopigmented or mm - hypopigmented or nodular skin lesions nodular skin lesions common - nose common - nose deformities caused by deformities caused by destruction of cartilaginous destruction of cartilaginous septum by organisms; septum by organisms; involvement of peripheral involvement of peripheral nerves not severenerves not severe
Staging of tuberculosis
M. tuberculosis - occurs in 2 forms
Primary tuberculosis - seen in individuals who have never Primary tuberculosis - seen in individuals who have never been exposed to organismbeen exposed to organism
Organisms enter host by several routes including skin, Organisms enter host by several routes including skin, genitourinary tract, alimentary tract - most acquire through genitourinary tract, alimentary tract - most acquire through respiratory tractrespiratory tract
Inhaled organisms become deposited in alveoli of the lung Inhaled organisms become deposited in alveoli of the lung and are phagocytized by alveolar macrophages where they and are phagocytized by alveolar macrophages where they multiplymultiply
Organisms generally encounter little host resistance; are Organisms generally encounter little host resistance; are carried to lymph nodes through the lymphaticscarried to lymph nodes through the lymphatics
If organisms escape lymph nodes, enter the blood via the If organisms escape lymph nodes, enter the blood via the thoracic duct - are disseminated throughout the body thoracic duct - are disseminated throughout the body producing numerous foci in various organsproducing numerous foci in various organs
Primary TB
Primary features of disease = tubercles & caseous Primary features of disease = tubercles & caseous necrosisnecrosis
Tubercles formed when macrophages surround Tubercles formed when macrophages surround organisms forming elongated epithelioid cells organisms forming elongated epithelioid cells arranged in concentric layers to form the arranged in concentric layers to form the granulomatous tubercles - tubercles are classically granulomatous tubercles - tubercles are classically surrounded by lymphocytes & fibroblastssurrounded by lymphocytes & fibroblasts
Caseous necrosis - characterized by disintegration Caseous necrosis - characterized by disintegration of tubercle forming a coagulated, homogenous, of tubercle forming a coagulated, homogenous, cheeselike masscheeselike mass
Progression of infection to disease depends on adequacy of CMI response - may be assisted by
humoral response
Good immune response - decreased multiplication Good immune response - decreased multiplication of organisms, cessation of dissemination and of organisms, cessation of dissemination and healing of lesions by fibrosis & calcification healing of lesions by fibrosis & calcification (Ghon complex) - organisms may remain viable in (Ghon complex) - organisms may remain viable in these lesions for many yearsthese lesions for many years
Poor immune response - progression to disease Poor immune response - progression to disease with liquification of caseous mass, rupture of with liquification of caseous mass, rupture of tubercle lesion and spread of organisms to other tubercle lesion and spread of organisms to other parts of lung and bodyparts of lung and body
Secondary or reactivation tuberculosis
Occurs in persons who have been previously Occurs in persons who have been previously infectedinfected
Associated with a breakdown in host’s cellular Associated with a breakdown in host’s cellular immune system (age, diabetes, obstructive immune system (age, diabetes, obstructive pulmonary disease or other diseases)pulmonary disease or other diseases)
Localized lesion becomes necrotic and liquifies - Localized lesion becomes necrotic and liquifies - may rupture into pulmonary vein and become may rupture into pulmonary vein and become disseminated to other body parts (miliary tb)disseminated to other body parts (miliary tb)
Mycobacteria Other Than Tuberculosis (MOTT)
Pulmonary diseasePulmonary disease Organisms most commonly involved include Organisms most commonly involved include M. M.
kansasiikansasii & & M. avium-intracellulareM. avium-intracellulare complex complex Usually occurs in middle-aged men with chronic Usually occurs in middle-aged men with chronic
lung diseaselung disease Predisposing conditions = pneumoconiosis (coal Predisposing conditions = pneumoconiosis (coal
miner’s disease), previous tb, chronic bronchitis, miner’s disease), previous tb, chronic bronchitis, chronic obstructive lung disease, lung malignancy, chronic obstructive lung disease, lung malignancy, AIDSAIDS
Mycobacteria Other Than Tuberculosis (MOTT)
Skin & soft tissue infectionsSkin & soft tissue infections Associated with Associated with M. fortuitum, M. chelonae, M. fortuitum, M. chelonae,
M. marinumM. marinum & & M. ulceransM. ulcerans M. fortuitum-chelonaeM. fortuitum-chelonae complex cause local complex cause local
abscesses at site of injections or after trauma abscesses at site of injections or after trauma & surgical wounds, corneal infections after & surgical wounds, corneal infections after penetrating injury to eye and endocarditis penetrating injury to eye and endocarditis after heart surgeryafter heart surgery
M. ulceransM. ulcerans - cause a cutaneous ulcer called - cause a cutaneous ulcer called Bairnsdale (Australia) or Buruli (Africa) ulcerBairnsdale (Australia) or Buruli (Africa) ulcer
Mycobacteria Other Than Tuberculosis (MOTT)
M. marinumM. marinum - found in - found in fresh & salt water; fresh & salt water; cutaneous granulomas cutaneous granulomas and ulcers associated and ulcers associated with swimming pools with swimming pools (swimming pool (swimming pool granulomas) and granulomas) and aquariums (fish tank aquariums (fish tank granulomas)granulomas)
Epidemiology HabitatHabitat
M. lepraeM. leprae - humans constitute major source; armadillos - humans constitute major source; armadillos recently implicatedrecently implicated
M. tuberculosisM. tuberculosis - humans constitute major source - humans constitute major source MOTT - environment (soil, plants, water)MOTT - environment (soil, plants, water)
TransmissionTransmission Leprosy - unclear; probably skin-skin contact or contact Leprosy - unclear; probably skin-skin contact or contact
with nasal secretions - requires susceptible host (most with nasal secretions - requires susceptible host (most humans not susceptible)humans not susceptible)
Tuberculosis - aerosols most common mode; may also be Tuberculosis - aerosols most common mode; may also be acquired by ingestion or direct skin contactacquired by ingestion or direct skin contact
MOTT - human to human transmission not involved; MOTT - human to human transmission not involved; requires contact with environmental sourcerequires contact with environmental source
Control & prevention
Leprosy - treatment of case contacts; long Leprosy - treatment of case contacts; long incubation period (3-10 years); isolation of incubation period (3-10 years); isolation of known cases no longer necessary for more known cases no longer necessary for more than 2 monthsthan 2 months
Control & prevention
TuberculosisTuberculosis Identification & treatment Identification & treatment
of infected personsof infected persons Skin testing - tuberculin Skin testing - tuberculin
(purified protein (purified protein derivative = PPD) derivative = PPD) injected subcutaneously; injected subcutaneously; positive = exposure - not positive = exposure - not diseasedisease
Control & prevention Xray evidence - Xray evidence -
calcified lesions may be calcified lesions may be evident as radiopaque evident as radiopaque area of lungarea of lung
Persons thought to be Persons thought to be candidates for active candidates for active diseases are treated for diseases are treated for 1 year with INH1 year with INH
Control & prevention
Vaccine = BCG (Bacille of Calmette & Vaccine = BCG (Bacille of Calmette & Guerin); uses laboratory strain of Guerin); uses laboratory strain of M. bovisM. bovis
Widely used throughout the world to Widely used throughout the world to immunize negative tuberculin reactorsimmunize negative tuberculin reactors
Rarely used in US - primarily because Rarely used in US - primarily because successful immunization causes conversion successful immunization causes conversion of person to positive tuberculin test of person to positive tuberculin test
Treatment
Leprosy - sulfones (esp. dapsone); infectivity Leprosy - sulfones (esp. dapsone); infectivity disappears in 50 days may need to take drug for disappears in 50 days may need to take drug for lifelife
Tuberculosis - isoniazid hydrazine (INH) = drug Tuberculosis - isoniazid hydrazine (INH) = drug of choice; multiple resistance common today; of choice; multiple resistance common today; known cases often treated with multiple drugs known cases often treated with multiple drugs including streptomycin, rifampin, ethambutol & including streptomycin, rifampin, ethambutol & amikacinamikacin
MOTT - usually highly resistant to drugs; often MOTT - usually highly resistant to drugs; often require surgical removal of lesions to treatrequire surgical removal of lesions to treat
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