Legionella Infections Bhargav

7/29/2019 Legionella Infections Bhargav

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LEGIONELLA INFECTIONS

PRESENTOR : Dr.Bhargav

MODERATOR : Dr.Prof.M.Senthilvelan sir

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Introduction

There was a outbreak of pneumonia in

persons who attended a convocation of

American legion in Philadelphia.

There were around 200 cases and 20 deaths.

So there was a huge , expensive medical

investigation carried out and it was discovered

that legionella was the causative organism

from the cooling towers.


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organism

It is gram negative ,aerobic , fastidious ,

facultative intracellular organism

,coccobacillus , motile ,flagellated ,non

encapsulated.

There are around 50 species and 70 serotypes

Around 18 species will cause human

infections.


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organism

Most common among them are L.pneumophilia

,L.macdadei ,L.longbeachae.L.bozemanii ,L

.dumoffii.

Of all the species serotype 1 is most common

causing 70-90% of the infection

The incubation period on average 2 days for

pontiac fever and 7 days for legionnaires disease Commonly occurs in streams/lakes/cooling

towers/ geysers.


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organism

They grow more when it is protein substrate.

For culturing they need media containing ironand cystein

Buffered charcoal yeast extract is the commonmedium that is used.

It is closely related to the genus coxiella

causing Q fever. It is easily killed by formalin , glutaraldehyde ,

chlorine and ethyl alcohol.


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habitat

ubiquitous aquatic

Warm water-hot water springs

Cooling tower/mist machine/spa Water heater/swimming pool

Potable water plumbing/showers

The L.longbeachae which can grow in pottingsoil and soil as well as in water.


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biofilm


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Factors that increase colonisation

Presence of free living amoeba

Warm water

Rainfall Humidity

Sediment and scaling

The cooling towers are over estimated theydidnt satisfy the koch postulates.80% of

cooling towers showd their presence.


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Transmission

There is no person to person transmission

Aerosols

Aspiration Direct instillation

In hospital acquired cases

Micro apiration (GA) Nebulizers / Humidifiers


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pathogenesis

Through aerosol transmission they enter thelung there they attach to the epithelium.

Later they are engulfed by the alveolar

macrophages. They resist the lysosomic degradation by first

multiplying in ER.

Both cellular immunity and humoral immunityacts. However neutrophils and antibodiesseems to have no big role.


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pathogenesis


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pathogenesis


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Virulence factors

Type 4 pili

Flagella

Porin

LPS

MIP

Heat shock protein

Protein secretion system type 2 and 4

And many other enzymes


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terms

Legionellosisthe disease caused by legionella

are together called legionellosis

Legionnaires disease-pneumonia caused by

legionella is called legionnaires disease.

Pontiac fever-acute , febrile , self limited

disese caused by this organism.


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epidemiology


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Risk factors

Male gender

Cigarette smoking

Chronic heart disease /lung disease

Chronic kidney disease

Chemotheray

TNF-alfa inhibitor use

Corticosteroid use

Alcohol

Recent surgery in GA


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risk factors

Overnight travel

Recent plumbing work in the home

Whirlpool spas Hot water springs

Nebulization ,humidifiers , nasogastric tubes .

Near drowning


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Clinical features

Pontiac fever

It is acute , febrile , self limiting flu like illness.

The incubation period is from hours to 2 days.

Myalgia

Fatigue

Headache

Malaise

Diarrhea

Nausea

Abd pain


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continued

Fever occurs in 90% individuals(mostly with

chills)

Headache in 80%.

The secondary attack rates are high.

It is diagnosed by serology.

No treatment is usually necessary.


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Legionnaires disease

It is often included in the differential diagnosisof atypical pneumonia because it usuallyproduces non-productive cough.

It is more severe than other atypicalpneumonia

But the course and prognosis are similar to

streptococcal pneumonia. All the clinical features and radiological

findings are also similar


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Symptoms and signs

Fever usually with chills and rigors

Normally preceded by prodrome of

headache/malaise/myalgia.

Non productive cough usually

Dyspnoea

Some times blood streaked sputum Rarely chest pain


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Symptoms and signs

Diarrhea/abdominal pain

Confusion /altered sensorium

Temperature will be high >104 Relative bradycardia

Focal rales early

Consolidation later Pleural effusion


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Laboratory findings

Hyponatremia

Hypophosphatemia

Raised liver enzymes Haematuria

proteinuria


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Radiological findings

They can be present or absent at the time ofpresentation.

Patchy infiltrations

Consolidation Pleural effusion

In immunocompramised persons

Round nodular opacities Cavities -10%

Complete disappearance takes 1-4 months


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Extrapulmonary manifestations

Blood borne dissemination or direct

instillation

Most common site is heart- pericarditis,

myocarditis, prosthetic valve endocarditis

Others are brain , liver ,spleen , kidneys

There it forms microabscess

Arthritis, peritonitis, sinusitis can occur

Mostly in immunocompramised persons


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staining

Material obtained from sterile sites like lungtissue and pleural fluid

Presence of numerous leucocytes in absence

of organism is the usual picture If seen appear a small gram negative cocco-

bacilli

Direct fluroscence antibody testing is highlyspecific , rapid test but is less sensitive thanculture


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Antibody detection

Four fold rise in titre diagnostic

1:128 with circumstantial evidence can be

considered

Serolgy is useful in epidemiolgic studies

Limitation of its use is it requries 12 weeks for

the detection of antibody response.


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Urinary antigen

Rapid , inexpensive , easy to perform , highlysensitive and specific.

The antigen in urine will be present from 3

days to 2 months Even with treatment of antibiotics it is not

affected

It is available only for legionella serotype 1 Enzyme assays and immunochromatograhic

assay are also available


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culture

It requires 3-5 days

Buffered charcoal yeast extract media is used

It has to be pretreated with heat , acid andantibiotics to kill the other microbial flora

It is higly sensitive and specific


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Molecular methods

Direct fluroscence antibody stains are

available both monoclonal and polyclonal

PCR with DNA probes are highly sensitive and

specific than all other methods


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treatment

Beta-lactams and aminoglycosides are not

effective

The antibiotics which can attain high

intracellular concentration are effective like

macrolides, quinalones and tetracyclines.

Quinalones are preferred in transplant

patients as it have lesser interaction with

chemotherapeutic agents


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treatment

Clinical response takes 3-5 days

Total duration of therapy is 10-14 days in

immunocompetent persons and 3 weeks in

immunocompramised persons

Trimethoprim, imepenem and clindamycin

have both success and failures in studies

Combination of rifamin has shown failure in

some studies


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prognosis

Depends on

Underlying disease and its severity

Immune status

Timing of administration of antibiotc

Severity of pneumonia

10% mortality even in treated patients

80%mortality in immunocompramisedwithout treatment


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prophylaxis

No vaccine is available

Chemoprophylaxis with macrolides in

immunocompramised persons is considered


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prevention

Heat and Flush:

Heat hot water >160 oF

Flush through ALL fixtures at this temperature for >= 5 minutes.

Flow should be about the width of a pencil.

Hyperchlorination:

Add chlorine to the hot water system.

Flush chlorine through all fixtures until it is >=2.0 ppm free chlorine, and pHis between 7.0 and 8.0

Keep fixture closed for 2-24 hours, then flush thoroughly.


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prevention

1) Chlorine Injection

- Drawbacks: corrosive to pipes, dangerous chemicals

2) Chlorine Dioxide- Drawbacks: takes time, treatment failures have beenreported, dangerous chemicals, needs monitoring

3) Copper Silver Ionization System

- Drawbacks: Expensive, needs monitoring


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thankyou

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Legionella Infections Bhargav