legionella, listeria and corynebacteria also,

Legionella, ListeriaLegionella, Listeriaand Corynebacteriaand Corynebacteria

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LegionellaLegionella

52 genetically defined species and 52 genetically defined species and about half are pathogenic to humans. about half are pathogenic to humans. Thin Gram negative rods with unusual Thin Gram negative rods with unusual complex nutritional requirements :complex nutritional requirements :

eg high Fe and cysteine.eg high Fe and cysteine.

Not related to other respiratory Not related to other respiratory pathogens.pathogens.


Legionella pneumophilaLegionella pneumophila

Others associated with infection in the Others associated with infection in the compromised :compromised :

L. micdadeiL. micdadeiL. bozemaniiL. bozemaniiL. longbeachaeL. longbeachaeL. dumoffiiL. dumoffii


Legionella pneumophilaLegionella pneumophila::

First recognised as a pathogen in 1976 First recognised as a pathogen in 1976 following a major outbreak amongst following a major outbreak amongst American Legionnaires in American Legionnaires in Philadelphia ->180 affected.Philadelphia ->180 affected.

Subsequently recognised as a cause of Subsequently recognised as a cause of disease as far back as 1947 and an disease as far back as 1947 and an outbreak in 1957.outbreak in 1957.


Ubiquitous in nature and can be isolated Ubiquitous in nature and can be isolated from terrestrial and aquatic habitats and from terrestrial and aquatic habitats and from patients with LD. Isolated from lakes, from patients with LD. Isolated from lakes, streams and soil in small numbers.streams and soil in small numbers.

It is relatively resistant to heat and chlorine. It is relatively resistant to heat and chlorine. (It appears to go into some form of (It appears to go into some form of suspended animation in adverse conditions.) suspended animation in adverse conditions.) It is normally spread through water It is normally spread through water distribution or air conditioning systems in distribution or air conditioning systems in which high numbers may be found.which high numbers may be found.


Outbreaks seem to occur at the end of Outbreaks seem to occur at the end of the summer but cases may occur all the summer but cases may occur all year round as it is found in hot water year round as it is found in hot water tanks, and whirlpool spas (where it tanks, and whirlpool spas (where it multiplies readily at 35-45oCmultiplies readily at 35-45oC). ).

Spread by inhalation of aerosols from Spread by inhalation of aerosols from showers etc.showers etc.

NOT spread from person to person.NOT spread from person to person.


Annual prevalence in US is steady at Annual prevalence in US is steady at about 0.5 per 100,000. It is likely about 0.5 per 100,000. It is likely that many cases are undiagnosed.that many cases are undiagnosed.


Prevention is by:Prevention is by:

Maintenance and cleaning of A/C Maintenance and cleaning of A/C systems.systems.

Improved design of water systems Improved design of water systems and elimination of dead legs,and elimination of dead legs,

Hyperchlorination,Hyperchlorination,

Heating water to 63oC.Heating water to 63oC.


Pathogenesis.Pathogenesis.

L. pneumophila is anL. pneumophila is an intracellular parasite intracellular parasite that grows in alveolar macrophages and that grows in alveolar macrophages and monocytes.monocytes.Phagocytosed cells are protected from Phagocytosed cells are protected from intracellular killing by lysosomal fusion and intracellular killing by lysosomal fusion and acidification.acidification.Virulent strains are difficult to distinguish Virulent strains are difficult to distinguish from avirulent strains. Virulence seems to from avirulent strains. Virulence seems to depend on proteolytic enzymes, lipases, depend on proteolytic enzymes, lipases, phosphatases and nucleases.phosphatases and nucleases.


Pontiac FeverPontiac Fever : :

A mild self-limiting disease - mild cough, A mild self-limiting disease - mild cough, sore throat, mild headache and fever.sore throat, mild headache and fever.

No treatment necessary and it resolves No treatment necessary and it resolves in in

2-5 days. Possibly due to inhalation of 2-5 days. Possibly due to inhalation of antigen rather than bacterial invasion.antigen rather than bacterial invasion.

Sometimes shows high attack rates Sometimes shows high attack rates (95%)in outbreaks(95%)in outbreaks


Legionnaires Disease:Legionnaires Disease:In the elderly - often who are In the elderly - often who are immunocompromised for some reason immunocompromised for some reason a more severe disease which is an a more severe disease which is an atypical pneumonia. atypical pneumonia.

There are 18 serotypes– serogroup 1 is There are 18 serotypes– serogroup 1 is the most pathogenic and seems to the most pathogenic and seems to cause 95% of such infections in these cause 95% of such infections in these islands.islands.

Low attack rates in outbreaks (0.5-5.0%)Low attack rates in outbreaks (0.5-5.0%)


Predisposing factors:Predisposing factors:

Smoking, malignancy, diabetes, Aids, Smoking, malignancy, diabetes, Aids, end-stage renal disease, and alcohol end-stage renal disease, and alcohol abuse.abuse.

Male : Female 2.5 : 1Male : Female 2.5 : 1

Very rare in those under 20Very rare in those under 20


Legionnaires Disease cont’dLegionnaires Disease cont’d

Prior to the onset of pneumonia Prior to the onset of pneumonia intestinal disorders are common intestinal disorders are common followed by high fevers and chills and followed by high fevers and chills and muscle aches.muscle aches.

Followed by dry cough, and chest and Followed by dry cough, and chest and abdominal pains.abdominal pains.

Fatality at about 10% usually as a result Fatality at about 10% usually as a result of respiratory failureof respiratory failure


Diagnosis Diagnosis Culture of bronchial washings, pleural Culture of bronchial washings, pleural

fluid and possibly other body fluids. fluid and possibly other body fluids. Culture using buffered charcoal yeast Culture using buffered charcoal yeast extract agar with iron and cysteine. extract agar with iron and cysteine.

Growth may take 5 (Growth may take 5 (L. pneumophilaL. pneumophila)-)-10 days (other species).10 days (other species).


Antigen detection in patient’s urine – Antigen detection in patient’s urine – ELISA for Serotype 1 only. ELISA for Serotype 1 only.

Serology for retrospective diagnosis: Serology for retrospective diagnosis: FAT,FAT,

Rapid microagglutination Test, RIARapid microagglutination Test, RIA or or ELISA.ELISA.

Antibody response in 8 daysAntibody response in 8 days

4-fold rise in titre or a titre of 1:256 is 4-fold rise in titre or a titre of 1:256 is usually diagnostic. usually diagnostic.


Treatment:Treatment:

Conventional sensitivity tests are unreliable Conventional sensitivity tests are unreliable but but L. pneumophilaL. pneumophila is susceptible to is susceptible to rifampicin, erythromycin, quinolones and rifampicin, erythromycin, quinolones and tetracyclines. All these have good tetracyclines. All these have good intracellular penetration. intracellular penetration.

Beta lactams and aminoglycosides are Beta lactams and aminoglycosides are ineffectiveineffective

IV erythromycin is preferred.IV erythromycin is preferred.

ListeriaListeria

Two species may be pathogenic – mostly Two species may be pathogenic – mostly

Listeria monocytogenesListeria monocytogenes and and occasionally occasionally

L. ivanovii. L. ivanovii.

L. innocua, L. welshimeri and L. seeligeri L. innocua, L. welshimeri and L. seeligeri are non pathogenic.are non pathogenic.

Up to 5% of healthy adults carry Listeria. Up to 5% of healthy adults carry Listeria.

ListeriaListeria

Widespread in nature but infections are rare Widespread in nature but infections are rare in the general population but may cause in the general population but may cause life threatening infections usually life threatening infections usually bacteraemia or meningo-encephalitis in bacteraemia or meningo-encephalitis in susceptible groups which are: susceptible groups which are:

Post 20 weeks of pregnancy, Post 20 weeks of pregnancy, neonates neonates and the immunosuppressed.and the immunosuppressed.

Mortality highest in infants of septic mothers Mortality highest in infants of septic mothers or the severely immunocompromised.or the severely immunocompromised.

ListeriaListeria

Short intracellular Gram-positive rods, but in Short intracellular Gram-positive rods, but in clinical specimens may appear Gram clinical specimens may appear Gram variable and look like diphtheroids or variable and look like diphtheroids or cocci. Motile with tumbling motility.cocci. Motile with tumbling motility.

Grow on blood agar – There are no Grow on blood agar – There are no identifiable toxins but virulent strains are identifiable toxins but virulent strains are haemolytic. Animal studies suggest the haemolytic. Animal studies suggest the production of listeriolysin which protects production of listeriolysin which protects the organism after phagocytosis and the organism after phagocytosis and facilitates the extraction of ironfacilitates the extraction of iron

ListeriaListeria

Grow best at 30 – 37oC but can grow Grow best at 30 – 37oC but can grow at at

4 -10oC. Some claim it may grow at 4 -10oC. Some claim it may grow at 0oC.0oC.

Definitive identification by Definitive identification by biochemistry or serologybiochemistry or serology

ListeriaListeria

Neonatal disease:Neonatal disease:

Early onset: acquired transplacentally. Early onset: acquired transplacentally. Disseminated abscesses and Disseminated abscesses and granulomas with high mortality if granulomas with high mortality if untreated.untreated.

Late onset: 2-3 weeks after birth Late onset: 2-3 weeks after birth meningitis or meningoencephalitis meningitis or meningoencephalitis and septicaemiaand septicaemia

ListeriaListeria

Treatment: Penicillin or ampicillin Treatment: Penicillin or ampicillin alone or with an aminoglycoside.alone or with an aminoglycoside.

No vaccine is available and because of No vaccine is available and because of the ubiquitous nature of the the ubiquitous nature of the organism and the sporadic infections, organism and the sporadic infections, prevention and control are difficult.prevention and control are difficult.

ListeriaListeria

Reservoir: Domestic and wild animals, Reservoir: Domestic and wild animals, water and mud.water and mud.

Contaminated silage gives rise to Contaminated silage gives rise to listeriosis in animals.listeriosis in animals.

Faecal carriage in man in about 5%Faecal carriage in man in about 5%

ListeriaListeria

Listeria is found in a wide range of Listeria is found in a wide range of foods including fish, meat and foods including fish, meat and vegetables and consequently in food vegetables and consequently in food products such as soft cheeses and products such as soft cheeses and those not made with pasteurised milk. those not made with pasteurised milk.

A relatively recent outbreak involved A relatively recent outbreak involved pork pate from Brussels.pork pate from Brussels.

ListeriaListeria

Its ability to grow at 4oC and survive Its ability to grow at 4oC and survive temperatures of 70oC has temperatures of 70oC has implications in the management of implications in the management of cook chill catering.cook chill catering.

Also in ready prepared meals bought Also in ready prepared meals bought in supermarkets.in supermarkets.

CorynebacteriaCorynebacteria

The genus includes the diphtheria The genus includes the diphtheria bacillus as well as a number of bacillus as well as a number of commensals and pathogens of man commensals and pathogens of man and animals.and animals.

These are usually referred to as These are usually referred to as coryneforms or diphtheroids.coryneforms or diphtheroids.

These are pleomorphic gram-positive These are pleomorphic gram-positive rods arranged as pallisades.rods arranged as pallisades.


C. diphtheriaeC. diphtheriae is the type strain It is is the type strain It is aerobic and facultatively anaerobic aerobic and facultatively anaerobic non-sporing non-motile and non-non-sporing non-motile and non-capsulate.capsulate.

It is grown on media containing blood It is grown on media containing blood or serum and produces characteristic or serum and produces characteristic black colonies on blood tellurite black colonies on blood tellurite medium.medium.


Three types of colonies may be Three types of colonies may be observed :observed : Large – gravisLarge – gravis

Medium – intermdius Medium – intermdius

Small – mitis.Small – mitis.

Historically these reflected the severity Historically these reflected the severity of the infection. Gravis and of the infection. Gravis and intermedius are usually toxigenic due intermedius are usually toxigenic due to the presence of a bacteriophageto the presence of a bacteriophage


Diphtheria is an acute infection of the Diphtheria is an acute infection of the tonsils, pharynx, nose and other tonsils, pharynx, nose and other mucous membranes or even skin and mucous membranes or even skin and on occasion the conjunctiva and on occasion the conjunctiva and genitals.genitals.

A greyish membrane covers much of A greyish membrane covers much of the throat and is surrounded by the throat and is surrounded by inflammation. The throat is inflammation. The throat is moderately sore and the patient will moderately sore and the patient will have enlarged cervical lymph nodes.have enlarged cervical lymph nodes.


Diphtheria should be differentiated Diphtheria should be differentiated from other causes of sore throat and from other causes of sore throat and premature use of antibiotics may premature use of antibiotics may delay diagnosis with fatal results. delay diagnosis with fatal results.

Specific treatment with antibiotics and Specific treatment with antibiotics and antitoxin is indicated even if lab antitoxin is indicated even if lab results are negative.results are negative.


Man is the reservoir of this bacterium. Man is the reservoir of this bacterium. The disease is normally manifest in The disease is normally manifest in the colder months. Usually the colder months. Usually unvaccinated children of less than 15 unvaccinated children of less than 15 y. This is a story of a very successful y. This is a story of a very successful vaccination programme. vaccination programme.

It used to be very common but now It used to be very common but now diphtheria is very rare.diphtheria is very rare.


Spread is by direct contact with patient Spread is by direct contact with patient or articles soiled with discharges. Raw or articles soiled with discharges. Raw milk has been a vehicle.milk has been a vehicle.

Incubation is 2-5 days.Incubation is 2-5 days.

Communicability depends on the Communicability depends on the success of the treatment which if success of the treatment which if good, will prevent carriage and good, will prevent carriage and spread. Rarely carriers may shed for 6 spread. Rarely carriers may shed for 6 months or more.months or more.


Non diphtheria coryneforms include :Non diphtheria coryneforms include :

C.ulceransC.ulcerans Acute pharyngitisAcute pharyngitis

C. haemolyticumC. haemolyticum

C.minutissimumC.minutissimum Cutaneous Cutaneous infectionsinfections

C.jeikeiumC.jeikeium


C.pseudotuberculosisC.pseudotuberculosis causing causing Granulomatous Granulomatous

lymphadenitis.lymphadenitis.

C.jeikeiumC.jeikeium Infective endocarditisInfective endocarditis

C.xerosisC.xerosis

C.pseudodiphtheriticumC.pseudodiphtheriticum

C.bovisC.bovis


C.jeikeiumC.jeikeium Line shunt and cannula Line shunt and cannula C.xerosisC.xerosisC.bovisC.bovis

C.equiC.equi necrotising pneumonianecrotising pneumonia

CDC group D-2 Complicated UTI CDC group D-2 Complicated UTI (abnormality or stones)(abnormality or stones)

legionella, listeria and corynebacteria also,

Documents

cause of disease

severe disease

high numbers

high attack rates

high fevers

heating water

water distribution

endstage renal disease