RevisionRevision

Term OneTerm One

QA SystemsQA Systems

Quality Assurance measures apply to the laboratory analytical work overall, which includes;

•Traceability of changes to SOPs and records

•identifying the person having the overall responsibility for quality•having laboratory equipment calibrated to recognised standards>Using only QA.ed materials

•Using reference materials +ve and -ve

•Validating analyses•Internal proficiency testing.

•Joining proficiency testing schemes with other laboratories doing similar tests

>Using correct SOP for each method/activity

•Using correct record sheets

QC QC systemssystems

• reagent blanks;reagent blanks;

• verified standard verified standard solutions;solutions;

• check samples check samples (from both within (from both within the lab and from the lab and from outside);outside);

% Fat

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• blind samples

• replicate analyses;

• and control charts

• Positive and negative controls

• All materials QC ed.

Quality control measures apply to each analytical test in the laboratory byuse of:

Control chart

Keeping track of theKeeping track of the

samplessamples

• Sample registration gives each sample a unique lab number.

• The sample register records all the information about the sample.

• Just like a sample’s passport, you should not confuse any sample with any other.

• The history of the sample should be traceable throughout.

Samples recorded on receipt

Lab. No. F7-002

Sample integrity

Beta ( Beta ( ββ ) hemolysis ) hemolysis (blood agar around bacterial colonies is (blood agar around bacterial colonies is completely clear, indicating completely clear, indicating completecomplete breakdown and breakdown and consumption of hemoglobin)consumption of hemoglobin)

Alpha (α) hemolysis (blood agar around bacterial colonies looks greenish-brown, indicating partial breakdown and consumption of hemoglobin)

Mixed culture from a throat swab; note several β-hemolytic colonies

Optochin (Taxo P) sensitivity

- Results with no zone of inhibition + results with a zone of inhibition

PP

Catalase TestCatalase Test

- +

Chapter 21: Diseases of Skin and Chapter 21: Diseases of Skin and EyesEyes

1. Staphylococcal Infections1. Staphylococcal Infections– Gram-positive cocci in irregular clustersGram-positive cocci in irregular clusters– Coagulase negative strains make up to 90% of skin Coagulase negative strains make up to 90% of skin

microbiota (microbiota (S. epidermidisS. epidermidis). Only pathogenic when ). Only pathogenic when skin is broken or through invasive entry.skin is broken or through invasive entry.

– Coagulase positive strains tend to be pathogenicCoagulase positive strains tend to be pathogenic. . Almost all pathogenic Almost all pathogenic S. aureusS. aureus strains make strains make coagulase. High correlation between ability to coagulase. High correlation between ability to produce coagulase and production of damaging produce coagulase and production of damaging toxinstoxins::

• LeukocidinLeukocidin: Destroys phagocytic white blood : Destroys phagocytic white blood cells.cells.

• Exfoliative toxinExfoliative toxin: Responsible for scalded skin : Responsible for scalded skin syndrome.syndrome.

• EnterotoxinsEnterotoxins: Affect gastrointestinal tract.: Affect gastrointestinal tract.

– S. aureusS. aureus is commonly found in nasal is commonly found in nasal passages. passages.

1. Staphylococcal Infections 1. Staphylococcal Infections (Continued)(Continued)

Common staphylococcal diseasesCommon staphylococcal diseasesA. Folliculitis:A. Folliculitis: Infection of hair follicles (pimples). Infection of hair follicles (pimples).

B. StyB. Sty: Infected eyelash follicle.: Infected eyelash follicle.

C. Boil (Abscess or Furuncle): C. Boil (Abscess or Furuncle): More serious infection More serious infection

of hair follicle in which pus is surrounded by of hair follicle in which pus is surrounded by

inflamed tissue.inflamed tissue. Usually painful and firm. Usually painful and firm.

D. Carbuncle: D. Carbuncle: Aggregate of several infected Aggregate of several infected

follicles (boils). May cause fever, chills, malaise, follicles (boils). May cause fever, chills, malaise,

and death if not treated.and death if not treated.

Forms a round, hard, deep area of inflammation, Forms a round, hard, deep area of inflammation,

typically on neck and back. typically on neck and back.

Damages surrounding tissue, with extensive Damages surrounding tissue, with extensive

scarring. scarring.

May need to lance and drain surgically.May need to lance and drain surgically.

1. Staphylococcal Infections 1. Staphylococcal Infections (Continued)(Continued)

Common staphylococcal Common staphylococcal diseasesdiseasesE. Impetigo: E. Impetigo: Problem in hospital Problem in hospital

nurseries and day care centers. Thin nurseries and day care centers. Thin walled vesicles on skin rupture and walled vesicles on skin rupture and crust over. crust over.

Caused by Caused by S. aureus, S. pyogenesS. aureus, S. pyogenes, or , or both. both. • Highly contagious, spread through direct Highly contagious, spread through direct

contact and fomites. contact and fomites.

• Occurs almost exclusively in children. Occurs almost exclusively in children.

• Rarely produces fever and easily treated Rarely produces fever and easily treated with penicillin.with penicillin.

Staphylococcal diseases Staphylococcal diseases (continued)(continued)6. Scalded skin syndrome: 6. Scalded skin syndrome: Caused by Caused by

toxemia from toxemia from SS. . aureusaureus strains with strains with two different exfoliative toxins. two different exfoliative toxins. •Large sheets of bright red skin peel off. Large sheets of bright red skin peel off.

•Usually observed in children under 2, but Usually observed in children under 2, but may occur in adults. may occur in adults.

•Bacteremia and septicemia may occur, Bacteremia and septicemia may occur, and can lead to death within 36 hours.and can lead to death within 36 hours.

•Require vigorous antibiotic treatment. Require vigorous antibiotic treatment.

•Exfoliative toxins are highly antigenic, Exfoliative toxins are highly antigenic, preventing recurrence. preventing recurrence.

Staphylococcal diseases Staphylococcal diseases (continued)(continued)7. Toxic shock syndrome (TSS): 7. Toxic shock syndrome (TSS): Fever, Fever,

vomiting, and sunburnlike rash, vomiting, and sunburnlike rash, followed by shock. Rash later peels.followed by shock. Rash later peels.• Presently about 25 cases per year reported.Presently about 25 cases per year reported.

• Most cases are associated with use of Most cases are associated with use of superabsorbent tampons.superabsorbent tampons.

• Males with boils or other staphylococcal Males with boils or other staphylococcal infections are at risk.infections are at risk.

• A few cases associated with use of A few cases associated with use of contraceptive sponge.contraceptive sponge.

• 5-15% of women have 5-15% of women have S. aureusS. aureus in vaginal in vaginal microflora.microflora.

• Only a small percentage of these strains Only a small percentage of these strains produce TSS.produce TSS.

In addition to skin infections, the staph In addition to skin infections, the staph bacteria can cause:bacteria can cause:

• BacteremiaBacteremia – a blood infection – a blood infection

• Deep abscessesDeep abscesses –an abscess that occurs –an abscess that occurs below the skin surfacebelow the skin surface

• EndocarditisEndocarditis – an infection on the valves – an infection on the valves of the heartof the heart

• Food poisoning Food poisoning – vomiting or diarrhea – vomiting or diarrhea caused by a staph toxincaused by a staph toxin

• LymphadenitisLymphadenitis – an infection of a lymph – an infection of a lymph gland, which causes it to be red, swollen gland, which causes it to be red, swollen and painfuland painful

• LymphangitisLymphangitis – an infection of the lymph – an infection of the lymph channels that drain to lymph glands, channels that drain to lymph glands, causing red streaks in the skincausing red streaks in the skin

• OsteomyelitisOsteomyelitis – a bone infection – a bone infection

• ParonychiaParonychia – an infection of the skin folds – an infection of the skin folds of the nailsof the nails

• Scalded skin syndromeScalded skin syndrome

• Septic arthritisSeptic arthritis – an infection of a joint, – an infection of a joint, like a hip or a kneelike a hip or a knee

• StyesStyes – an infection of the glands on the – an infection of the glands on the eyelideyelid

• Toxic shock syndromeToxic shock syndrome

MRSAMRSA

• MRSAMRSA stands for stands for Methicillin-Methicillin-Resistant Staphylococcus aureusResistant Staphylococcus aureus

• MRSA MRSA are are Staph aureusStaph aureus bacteria bacteria that have become resistant to this that have become resistant to this antibiotic.antibiotic.

2. Streptococcal Infections2. Streptococcal Infections– Gram-positive cocci in chains.Gram-positive cocci in chains.– Cause many disease including meningitis, Cause many disease including meningitis,

pneumonia, sore throat, otitis media, pneumonia, sore throat, otitis media, endocarditis childbirth fever, and dental endocarditis childbirth fever, and dental caries.caries.

– Produce multiple toxins and virulence Produce multiple toxins and virulence factors.factors.• StretokinasesStretokinases: Dissolve blood clots.: Dissolve blood clots.• ProteasesProteases: Destroy proteins.: Destroy proteins.• HyaluronidaseHyaluronidase: Breaks down connective tissue.: Breaks down connective tissue.• HemolysinsHemolysins: Lyse red blood cells. Alpha, beta, and : Lyse red blood cells. Alpha, beta, and

gamma hemolysis.gamma hemolysis.

– Beta hemolytic streptococci are often Beta hemolytic streptococci are often associated with human disease.associated with human disease.

– Streptococcus pyogenes Streptococcus pyogenes = = Group A Group A --hemolytichemolytic streptococci. streptococci.

– Infections are often localized, but can Infections are often localized, but can produce great damage when they reach produce great damage when they reach deeper tissue.deeper tissue.

Chapter 21: Diseases of Skin and Chapter 21: Diseases of Skin and EyesEyes

1. Staphylococcal Infections1. Staphylococcal Infections– Gram-positive cocci in irregular clustersGram-positive cocci in irregular clusters– Coagulase negative strains make up to 90% of skin Coagulase negative strains make up to 90% of skin

microbiota (microbiota (S. epidermidisS. epidermidis). Only pathogenic when ). Only pathogenic when skin is broken or through invasive entry.skin is broken or through invasive entry.

– Coagulase positive strains tend to be pathogenicCoagulase positive strains tend to be pathogenic. . Almost all pathogenic Almost all pathogenic S. aureusS. aureus strains make strains make coagulase. High correlation between ability to coagulase. High correlation between ability to produce coagulase and production of damaging produce coagulase and production of damaging toxinstoxins::

• LeukocidinLeukocidin: Destroys phagocytic white blood : Destroys phagocytic white blood cells.cells.

• Exfoliative toxinExfoliative toxin: Responsible for scalded skin : Responsible for scalded skin syndrome.syndrome.

• EnterotoxinsEnterotoxins: Affect gastrointestinal tract.: Affect gastrointestinal tract.– S. aureusS. aureus is commonly found in nasal passages. is commonly found in nasal passages.

1. Staphylococcal Infections 1. Staphylococcal Infections (Continued)(Continued)Common staphylococcal diseasesCommon staphylococcal diseases

A. Folliculitis:A. Folliculitis: Infection of hair follicles (pimples). Infection of hair follicles (pimples).

B. StyB. Sty: Infected eyelash follicle.: Infected eyelash follicle.

C. Boil (Abscess or Furuncle): C. Boil (Abscess or Furuncle): More serious infection of More serious infection of

hair follicle in which pus is surrounded by inflamed hair follicle in which pus is surrounded by inflamed

tissue.tissue. Usually painful and firm. Usually painful and firm.

D. Carbuncle: D. Carbuncle: Aggregate of several infected follicles Aggregate of several infected follicles

(boils). May cause fever, chills, malaise, and death if (boils). May cause fever, chills, malaise, and death if

not treated.not treated.

Forms a round, hard, deep area of inflammation, Forms a round, hard, deep area of inflammation,

typically on neck and back. typically on neck and back.

Damages surrounding tissue, with extensiveDamages surrounding tissue, with extensive

scarring. scarring.

May need to lance and drain surgically.May need to lance and drain surgically.

1. Staphylococcal Infections 1. Staphylococcal Infections (Continued)(Continued)

Common staphylococcal Common staphylococcal diseasesdiseasesE. Impetigo: E. Impetigo: Problem in hospital Problem in hospital

nurseries and day care centers. Thin nurseries and day care centers. Thin walled vesicles on skin rupture and walled vesicles on skin rupture and crust over. crust over.

Caused by Caused by S. aureus, S. pyogenesS. aureus, S. pyogenes, or , or both. both. • Highly contagious, spread through direct Highly contagious, spread through direct

contact and fomites. contact and fomites.

• Occurs almost exclusively in children. Occurs almost exclusively in children.

• Rarely produces fever and easily treated Rarely produces fever and easily treated with penicillin.with penicillin.

Staphylococcal diseases Staphylococcal diseases (continued)(continued)6. Scalded skin syndrome: 6. Scalded skin syndrome: Caused by Caused by

toxemia from toxemia from SS. . aureusaureus strains with strains with two different exfoliative toxins. two different exfoliative toxins. •Large sheets of bright red skin peel off. Large sheets of bright red skin peel off.

•Usually observed in children under 2, but Usually observed in children under 2, but may occur in adults. may occur in adults.

•Bacteremia and septicemia may occur, Bacteremia and septicemia may occur, and can lead to death within 36 hours.and can lead to death within 36 hours.

•Require vigorous antibiotic treatment. Require vigorous antibiotic treatment.

•Exfoliative toxins are highly antigenic, Exfoliative toxins are highly antigenic, preventing recurrence. preventing recurrence.

Staphylococcal diseases Staphylococcal diseases (continued)(continued)7. Toxic shock syndrome (TSS): 7. Toxic shock syndrome (TSS): Fever, Fever,

vomiting, and sunburnlike rash, vomiting, and sunburnlike rash, followed by shock. Rash later peels.followed by shock. Rash later peels.• Presently about 25 cases per year reported.Presently about 25 cases per year reported.

• Most cases are associated with use of Most cases are associated with use of superabsorbent tampons.superabsorbent tampons.

• Males with boils or other staphylococcal Males with boils or other staphylococcal infections are at risk.infections are at risk.

• A few cases associated with use of A few cases associated with use of contraceptive sponge.contraceptive sponge.

• 5-15% of women have 5-15% of women have S. aureusS. aureus in vaginal in vaginal microflora.microflora.

• Only a small percentage of these strains Only a small percentage of these strains produce TSS.produce TSS.

In addition to skin infections, the staph In addition to skin infections, the staph bacteria can cause:bacteria can cause:

• BacteremiaBacteremia – a blood infection – a blood infection

• Deep abscessesDeep abscesses –an abscess that occurs –an abscess that occurs below the skin surfacebelow the skin surface

• EndocarditisEndocarditis – an infection on the valves – an infection on the valves of the heartof the heart

• Food poisoning Food poisoning – vomiting or diarrhea – vomiting or diarrhea caused by a staph toxincaused by a staph toxin

• LymphadenitisLymphadenitis – an infection of a lymph – an infection of a lymph gland, which causes it to be red, swollen gland, which causes it to be red, swollen and painfuland painful

MRSAMRSA

• MRSAMRSA stands for stands for Methicillin-Methicillin-Resistant Staphylococcus aureusResistant Staphylococcus aureus

• MRSA MRSA are are Staph aureusStaph aureus bacteria bacteria that have become resistant to this that have become resistant to this antibiotic.antibiotic.

2. Streptococcal Infections2. Streptococcal Infections– Gram-positive cocci in chains.Gram-positive cocci in chains.– Cause many disease including meningitis, Cause many disease including meningitis,

pneumonia, sore throat, otitis media, pneumonia, sore throat, otitis media, endocarditis childbirth fever, and dental endocarditis childbirth fever, and dental caries.caries.

– Produce multiple toxins and virulence Produce multiple toxins and virulence factors.factors.• StretokinasesStretokinases: Dissolve blood clots.: Dissolve blood clots.• ProteasesProteases: Destroy proteins.: Destroy proteins.• HyaluronidaseHyaluronidase: Breaks down connective tissue.: Breaks down connective tissue.• HemolysinsHemolysins: Lyse red blood cells. Alpha, beta, and : Lyse red blood cells. Alpha, beta, and

gamma hemolysis.gamma hemolysis.

– Beta hemolytic streptococci are often Beta hemolytic streptococci are often associated with human disease.associated with human disease.

– Streptococcus pyogenes Streptococcus pyogenes = = Group A Group A --hemolytichemolytic streptococci. streptococci.

– Infections are often localized, but can Infections are often localized, but can produce great damage when they reach produce great damage when they reach deeper tissue.deeper tissue.

Common streptococcal skin diseasesCommon streptococcal skin diseases– ErysipelasErysipelas: From Greek erythos = red, : From Greek erythos = red,

and pella = skin. Also called St. and pella = skin. Also called St. Anthony’s fire. Common skin infection Anthony’s fire. Common skin infection associated with associated with SS. . pyogenespyogenes. . •Spread through contact or insect bites. Spread through contact or insect bites.

•Skin erupts into reddish patches with raised Skin erupts into reddish patches with raised margins.margins.

•High fever is common. High fever is common.

•Organisms can spread through lymphatics Organisms can spread through lymphatics and cause septicemia, abscesses, and cause septicemia, abscesses, pneumonia, endocarditis, arthritis, and even pneumonia, endocarditis, arthritis, and even death if untreated.death if untreated.

•Mortality was high before use of antibiotics.Mortality was high before use of antibiotics.

•Responds well to antibiotic (Responds well to antibiotic (-lactams) -lactams) treatment.treatment.

Common streptococcal skin diseasesCommon streptococcal skin diseases– Flesh eating bacterial infectionsFlesh eating bacterial infections: :

•Caused by Caused by invasiveinvasive group A streptococci. group A streptococci.

•15,000 cases per year in U.S.15,000 cases per year in U.S.

•Exotoxin A acts as superantigen causing Exotoxin A acts as superantigen causing damage by the immune system.damage by the immune system.

•Attacks and destroys muscle (myositis), muscle Attacks and destroys muscle (myositis), muscle covering (fasciitis), and solid tissue (cellulitis).covering (fasciitis), and solid tissue (cellulitis).

•Can destroy several inches of tissue per hour.Can destroy several inches of tissue per hour.

•Antibiotics are not effective because dead Antibiotics are not effective because dead tissue has no circulation.tissue has no circulation.

•Requires amputation or surgical removal of Requires amputation or surgical removal of tissue.tissue.

•Mortality rate up to 40%Mortality rate up to 40%

– Impetigo: Refer to previous description.Impetigo: Refer to previous description.

Flesh eating bacterial infectionsFlesh eating bacterial infections

•Caused by Caused by invasiveinvasive group A streptococci. group A streptococci.

•15,000 cases per year in U.S.15,000 cases per year in U.S.

•Exotoxin A acts as superantigen causing Exotoxin A acts as superantigen causing damage by the immune system.damage by the immune system.

•Attacks and destroys muscle (myositis), Attacks and destroys muscle (myositis), muscle covering (fasciitis), and solid tissue muscle covering (fasciitis), and solid tissue (cellulitis).(cellulitis).

•Can destroy several inches of tissue per hour.Can destroy several inches of tissue per hour.

•Antibiotics are not effective because dead Antibiotics are not effective because dead tissue has no circulation.tissue has no circulation.

•Requires amputation or surgical removal of Requires amputation or surgical removal of tissue.tissue.

•Mortality rate up to 40%Mortality rate up to 40%

BacillusBacillus

• ClassificationClassification– All are large Gram-positive bacilliAll are large Gram-positive bacilli– Are aerobicAre aerobic– Form endospores Form endospores – Most are found in dust and soilMost are found in dust and soil– Bacillus anthracisBacillus anthracis is the major pathogen in the is the major pathogen in the

groupgroup

• Morphology and Cultural Characteristics Morphology and Cultural Characteristics ((Bacillus anthracisBacillus anthracis))

BacillusBacillus

– Grow well on ordinary lab media producing large Grow well on ordinary lab media producing large granular colonies with a coarse texture.granular colonies with a coarse texture.

• Virulence factors Virulence factors – Capsule helps organism to resist phagocytosis but Capsule helps organism to resist phagocytosis but

antibodies are not antibodies are not protective.protective.– Exotoxin is very complex and is produced only when Exotoxin is very complex and is produced only when

the bacteria is growing in animal tissues.the bacteria is growing in animal tissues.• Toxin production is mediated by a temperature sensitive Toxin production is mediated by a temperature sensitive

plasmid. plasmid. • The toxin consists of three protein components (maximum The toxin consists of three protein components (maximum

toxicity occurs when all three components are present). toxicity occurs when all three components are present).

      

BacillusBacillus

• Clinical significance Clinical significance – Anthrax which is the disease caused by Anthrax which is the disease caused by B. B.

anthracisanthracis is essentially a disease of animals who is essentially a disease of animals who acquire the organism by ingestion or inhalation of acquire the organism by ingestion or inhalation of spores. spores. • The spores are extremely resistant to adverse The spores are extremely resistant to adverse

chemicals and physical environments. chemicals and physical environments. • They may remain a source of infection in soil for 2-3 They may remain a source of infection in soil for 2-3

years.years.

– Man acquires anthrax usually from contact with Man acquires anthrax usually from contact with animal products; less commonly from working in animal products; less commonly from working in an agricultural setting with infected animals. an agricultural setting with infected animals.

BacillusBacillus

– Man may acquire the organism through skin Man may acquire the organism through skin abrasions, by inhalation of spores, or by abrasions, by inhalation of spores, or by ingestion. The disease that develops ingestion. The disease that develops depends upon the mode of transmission:depends upon the mode of transmission:• Pulmonary (Woolsorter‘s disease) Spores are Pulmonary (Woolsorter‘s disease) Spores are

inhaled and germinate in the lungs where they inhaled and germinate in the lungs where they multiply and spread to cause a fatal multiply and spread to cause a fatal septicemia or meningitis. septicemia or meningitis.

– This is the most serious form of the disease.This is the most serious form of the disease.

•   Intestinal anthrax results from ingestion of spores.Intestinal anthrax results from ingestion of spores.

  

BacillusBacillus

• Antibiotic susceptibility and treatmentAntibiotic susceptibility and treatment– Penicillin or tetracyclinePenicillin or tetracycline– A short-term PA vaccine is available for industrial A short-term PA vaccine is available for industrial

workers and others at high risk.workers and others at high risk.

• Other Other Bacillus speciesBacillus species– Bacillus subtilisBacillus subtilis, and occasional other species , and occasional other species

may occasionally cause opportunistic infectionsmay occasionally cause opportunistic infections..– Bacillus cereusBacillus cereus is a major cause of enterotoxin is a major cause of enterotoxin

food poisoning; food poisoning; • The toxin is protein in nature and can be destroyed by heating; The toxin is protein in nature and can be destroyed by heating; • Food poisoning occurs after ingestion of pre-formed toxin;Food poisoning occurs after ingestion of pre-formed toxin;

– Vomiting occurs 1-5 hours after ingestionVomiting occurs 1-5 hours after ingestion  

BacillusBacillus

– B. cereusB. cereus is also an opportunistic pathogen is also an opportunistic pathogen that has been cultured from cases of that has been cultured from cases of septicemia, endocarditis, meningitis, wound septicemia, endocarditis, meningitis, wound infections, pneumonia, and fulminant eye infections, pneumonia, and fulminant eye infectionsinfections • In addition to the enterotoxin that bacteria may In addition to the enterotoxin that bacteria may

produce, a dermonecrotic and a lethal toxin, produce, a dermonecrotic and a lethal toxin, hemolysins, lecithinase, proteases, and nucleases hemolysins, lecithinase, proteases, and nucleases may be involved in its pathogenesismay be involved in its pathogenesis

• Clindamycin with or without gentamycin may be used Clindamycin with or without gentamycin may be used for treatment of infectionsfor treatment of infections

Clostridium

Clostridium form endospores under adverse environmental conditions

Spores are a survival mechanism

Spores are characterized on the basis of position, size and shape

Most Clostridium spp., including C. perfringens and C. botulinum, have ovoid subterminal (OST) spores

C. tetani have round terminal (RT) spores

Clostridium

Clostridium form endospores under adverse environmental conditions

Spores are a survival mechanism

Spores are characterized on the basis of position, size and shape

Most Clostridium spp., including C. perfringens and C. botulinum, have ovoid subterminal (OST) spores

C. tetani have round terminal (RT) spores

Clostridium perfringens

Micro & Macroscopic C. perfringens

NOTE: Large rectangular gram-positive bacilli

Inner beta-hemolysis = θ toxin Outer alpha-hemolysis = α toxin

NOTE: Double zone of hemolysis

Clostridial Cellulitis

Clostridium tetani

Clostridium tetani Gram Stain

NOTE: Round terminal spores give cells a “drumstick” or “tennis racket” appearance.

Opisthotonos in Tetanus Patient

Mechanism of Action of Tetanus Toxin

Clostridium botulinum

Mechanism of Action of Botulinum Toxin

Rates of Isolation of C. botulinum

and Botulinum

Toxin

• M. tuberculosisM. tuberculosis• major human diseasemajor human disease

– healthy peoplehealthy people • problems problems

– association with AIDSassociation with AIDS– multiple drug-resistancemultiple drug-resistance

Tuberculosis Tuberculosis (TB, consumption)(TB, consumption)

M. avium- M. intracellulareM. avium- M. intracellulare complex (complex (M. aviumM. avium))

• non-AIDSnon-AIDS– infection almost never infection almost never

• AIDS AIDS – major bacterial opportunistmajor bacterial opportunist

• multiple drug-resistance multiple drug-resistance

• spread from cattlespread from cattle

• infected cattle are culledinfected cattle are culled– positive skin testpositive skin test

• rarely seen in USrarely seen in US

M. bovisM. bovis

M. lepraeM. leprae• leprosyleprosy• major disease of third worldmajor disease of third world• Leprosy rates in Australia are only about Leprosy rates in Australia are only about

one case per million, one case per million, • but are higher in Aboriginal Australians but are higher in Aboriginal Australians

and immigrants from infected areas. and immigrants from infected areas. • Worldwide, leprosy is still endemic Worldwide, leprosy is still endemic

mostly in Africa and around India. mostly in Africa and around India. • There is also some leprosy in parts of There is also some leprosy in parts of

the USAthe USA

Laboratory diagnosis - Laboratory diagnosis -

tuberculosistuberculosis•skin testingskin testing

– delayed hypersensitivity delayed hypersensitivity – tuberculin tuberculin – protein purified derivative, protein purified derivative, PPDPPD

•X-rayX-ray

Laboratory diagnosis Laboratory diagnosis M. tuberculosisM. tuberculosis

• acid fast bacteria acid fast bacteria – sputum sputum

Positive skin test -Positive skin test -tuberculosistuberculosis

•indicates exposure to indicates exposure to organismorganism

•does not indicate active does not indicate active diseasedisease

Laboratory diagnosis Laboratory diagnosis M. tuberculosis M. tuberculosis (culture)(culture)

• grows very slowlygrows very slowly– several weeksseveral weeks– non-pigmented coloniesnon-pigmented colonies– niacin productionniacin production

*differentiates from other mycobacteriadifferentiates from other mycobacteria

Mycobacterium Mycobacterium lepraeleprae

Leprosy (Hansen's Leprosy (Hansen's Disease)Disease)

• M. lepraeM. leprae– causative agentcausative agent

• chronic disease chronic disease – disfigurementdisfigurement

• rarely seen in the U.S. rarely seen in the U.S.

• common in third worldcommon in third world• millions of cases millions of cases

• infects the skin infects the skin – low temperaturelow temperature

• tuberculoidtuberculoid• few organisms few organisms • active cell-mediated immunityactive cell-mediated immunity

• lepromatous lepromatous • immunosuppressionimmunosuppression• few organisms few organisms

LeprosyLeprosy

• lepromin lepromin – skin testingskin testing

• acid-fast stains acid-fast stains – skin biopsiesskin biopsies

• clinical picture clinical picture

LeprosyLeprosy

Corynebacterium diphtheriaeCorynebacterium diphtheriae

• Gram positiveGram positive

• strict aerobestrict aerobe

• pleomorphic (e.g. club-shaped)pleomorphic (e.g. club-shaped)

Corynebacterium diphtheriaeCorynebacterium diphtheriae

• infection infection – upper respiratory tract (pharynx)upper respiratory tract (pharynx)– pseudomembrane pseudomembrane – chocking chocking – bacteria do not spread systemicallybacteria do not spread systemically

.

DiphtheriaDiphtheria

• B binds to host cellB binds to host cell• A inhibits protein synthesisA inhibits protein synthesis• ADP-ribose moiety (NADH) ADP-ribose moiety (NADH) attaches attaches

– rare amino acid, diphthamide rare amino acid, diphthamide – elongation factor 2 inhibited elongation factor 2 inhibited

Diphtheria toxinDiphtheria toxin

• diphtheroidsdiphtheroids– other corynebacteriaother corynebacteria– propionibacteriapropionibacteria

C. diphtheriae C. diphtheriae should not be confusedshould not be confused with: with:

Corynebacterium spp.Corynebacterium spp.

Listeria monocytogenesListeria monocytogenes

ListeriosisListeriosis(invasive disease & non-(invasive disease & non-

invasive enteritis)invasive enteritis)

• The organism – The organism – G+ve ovoid to G+ve ovoid to rod-shaped bacteriumrod-shaped bacterium

• Widespread in environmentWidespread in environment

Listeria monocytogenesListeria monocytogenes

• CharacteristicsCharacteristics - grows in wide range of - grows in wide range of

temperatures (1 to 45temperatures (1 to 45oo C)C)

- survives freezing- survives freezing

- aerobic & anaerobic- aerobic & anaerobic

conditionsconditions

Listeria monocytogenesListeria monocytogenes

• The illness – The illness – invasive forminvasive form

- incubation – 30 days- incubation – 30 days

- flu’-like symptoms, diarrhoea,- flu’-like symptoms, diarrhoea,

vomiting, meningitis, vomiting, meningitis, septicaemia,septicaemia,

spontaneous abortion spontaneous abortion

Listeria monocytogenesListeria monocytogenes

• The illness – The illness – invasive invasive formform, continued, continued

- infective dose – 100 to 1 000 - infective dose – 100 to 1 000 cellscells

- pregnant women, newborn - pregnant women, newborn babies, the elderly & AIDS babies, the elderly & AIDS patientspatients

- Rx – penicillin, ampicillin +/- - Rx – penicillin, ampicillin +/- gentamicingentamicin

Listeria monocytogenesListeria monocytogenes

• The illness – The illness – non-invasivenon-invasive

- incubation – 18 hours- incubation – 18 hours - diarrhoea, fever, muscle pain,- diarrhoea, fever, muscle pain, headache, abdominal cramps &headache, abdominal cramps & vomiting vomiting

Listeria monocytogenesListeria monocytogenes

• The illness – The illness – non-invasivenon-invasive - infective dose – > 100 thou. - infective dose – > 100 thou.

cells/gmcells/gm

- all individuals susceptible- all individuals susceptible

- Rx - penicillin, ampicillin +/- - Rx - penicillin, ampicillin +/-

gentamicingentamicin

Listeria monocytogenesListeria monocytogenes• SourcesSources - human – - human – person-to-person rareperson-to-person rare

- animal – - animal – diseased animals shed in faeces, diseased animals shed in faeces,

contamination of red meat; silagecontamination of red meat; silage

- food – - food – ready-to-eat cooked food with longready-to-eat cooked food with long

shelf-lifeshelf-life

-- raw foodsraw foods

- environment – - environment – widespread in soil, water & widespread in soil, water & sewagesewage

(Hospitals & occupational exposure)(Hospitals & occupational exposure)

Listeria monocytogenesListeria monocytogenes

Listeriosis cases in NZ from 1980 to 2004

0

5

10

15

20

25

30

35

40

19

80

19

82

19

84

19

86

19

88

19

90

19

92

19

94

19

96

19

98

20

00

20

02

20

04

Year

Nu

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of

ca

se

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