Respiratory Tract Infections 12

8/3/2019 Respiratory Tract Infections 12

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RESPIRATORY TRACT

INFECTIONS

Presenter: Katisa Godwin MD


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Introduction

Infections of the upper and lower respiratorytract continue to be a major cause of morbidityand mortality throughout the world,

patients at the extremes of age or with pre-existing lung disease or immune suppressionbeing at particular risk.

Viruses are the most frequent cause of upper

respiratory illnesses, with bacteria beingresponsible for the majority of community- andhospital-acquired pneumonia in adults


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Anatomy of the Respiratory System


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URT

nose

nasal cavity

ethmoidal air cells frontal sinuses

maxillary sinuses

Sphenoidal sinuses

Pharynx

larynx


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LRT

trachea

Bronchi

bronchioles alveoli

Lung parenchyma


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TYPES OF RTIs

Upper respiratory tract infections

Lower respiratory tract infections


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URTIs

Burden

Predisposing factors

Aetiology pathogenesis

Types

Clinical features management


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Burden ofURTI

Up to of all symptomatic illness

Significant morbidity and direct health care

costs Children may have six to ten episodes a

year. Adult two to four

Occasionally leads to fatal illness Excessive use of antibiotics a major issue


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Predisposing factors

Age,

Mucociliary functions: cystic fibrosis, immotile

cilia syndrome.

Systemic dis., immune deficiency.: DM, AIDS,

CRF

Allergy: Nasal poliposis, asthma

Neoplasia

Environmental: smoking, air pollution,


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Aetiological agents

Viral 60% 90%

Bacterial

fungal


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Pathogenesis

Before a respiratory disease can beestablished, the following conditions need to

be met

There must be a sufficient number orsufficient "dose" of infectious agent inhaled.

The infectious particles must be airborne.

The infectious organism must remain alive

and viable while in the air. The organism must be deposited on

susceptible tissue in the host.


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Pathogenesis

Pathogenic mechanisms:-

Bacterial adherence factors = F and M proteins of

Strep. pyogenes, Hemagglutinins ofB. pertussis.

Extracellular toxins = diphtheria toxin; pertussistoxin.

Growth in host tissue = viruses, chlamydia sp.

Evasion of host defense mechanism = capsules of

Strep. pyogenes (also M protein), S. pneumoniaeand H. influenza by inhibiting phagocytes


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Types ofURTI

Common upper respiratory tract infections

include

Common cold Influenza

Sinusitis

pharyngitis/pharyngotonsilitis

Epiglottitis

laryngitis


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Common cold

Most common

Rhinoviruses are the most common viralagents

Other viruses implicated included

coronaviruses,

influenza C,

parainfluenza virus, adenoviruses,

and respiratory syncytial virus


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Common cold

Highly contagious, respiratory droplets

spread by

sneezing, coughing,

or hand contact with the nose, eyes, or face

75% of patients infected with rhinovirus

will have symptoms


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Common cold: clinical

presentations Has an incubation period of 2 4 days Sneezing

Coughing

hoarseness Malaise

Headache

nasal congestion

scratchy throat

clear, watery rhinorrhea

+ or - mild fever


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Common cold: diagnosis

Made on clinical grounds pt symptoms,

nasal exam showing reddened,

edematous mucosa, narrowed nasal

passages, and watery discharge

Viral isolation/culture is not practical


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Common Cold: Treatment

No curative treatment

Supportive therapy 10 treatment Fluids,

rest, humidification, and decongestants Analgesics, antihistamines are also helpful

Antibiotics not indicated


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Influenza: clinical presentations

Often necessary to differentiate influenza

from the common cold

Symptoms include high fever, exhaustion,generalized aches, and cough

Patients occasionally report headache,

nasal congestion, sneezing, and sore

throat


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Influenza : Diagnosis

Diagnosis is based on clinical signs and

symptoms

Nasopharyngeal swab or aspirate can beobtained for a rapid antigen test

Chest x-ray usually normal


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Influenza: Treatment

Analgesics and a cough suppressants for

supportive therapy

Amantadine and rimantadine (both atdoses of 200 mg/day) have been effective

at treating Influenza A.

Zanamivir and Tamiflu are effective for

patients with Influenza A and B, but with

less side effect


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Pharyngitis

90% viruses Epstein-Barr virus

Adenovirus

Influenza A, B Coxsackie A

Parainfluenzae

important bacteria includes

S. pyogenes C. diphtheriae

N. gonorrhoeae


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Pharyngitis: clinical presentations

Sore throat

Fever > 38 rC

Difficulty in swallowing Headache, fatigue

Muscle pain

pharyngotonsillar hyperemia / exudates

Soft palate petechia

Anterior cervical LAP


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Pharyngotonsilitis


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Cont..


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Pharyngitis: diagnosis

On PE: observe throat for tonsillar

exudates; obtain throat swab

Rapid streptococcal identification tests aremost commonly used; there is a sensitivity

of 80% and a specificity of 95%

Throat cultures may be collected if rapid

strep screen is negative


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Pharyngitis: Treatment

Symptomatic treatment includes saltwater gargles, PCM, cool-misthumidification, and throat lozenges

Antibiotics treatment is necessary to treatproven strep infections

Benzathine penicillin G 1.2 million units as asingle dose, is optimal therapy

For pen allergic pts, erythromycin 500mg poQID x 10 days or Azithromycin 500mg oncedaily x 3 days.


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Sinusitis

More common in adult than in children

Organisms

Viral Rhinovirus

Parainfluenzae

Bacterial

S. pneumoniae H. influenzae

fungal


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Sinusitis: clinical presentations

feeling of fullness and pressure over the

involved sinuses, nasal congestion, and

purulent nasal discharge

Postnasal drip

Headache

Tenderness on palpation over sinuses,


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Cont..


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Sinusitis: Diagnosis

Based on clinical signs and symptoms

Sinus radiographs may reveal cloudinessand air fluid levels


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Sinusitis: Treatment

Supportive

antibiotics


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Acute laryngotracheobronchitis

(croup)

Croup or laryngotracheobronchitis is a

clinical syndrome

COMMON cause of upper airwayobstruction usually mild & self limiting

BUT is also the commonest cause of

potentially life threatening airway

obstruction in childhood


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ALTB: Causes

Commonest cause is viral

parainfluenza, RSV

Influenza virus A and B


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ALTB: clinical presentations

Airway obstruction(insp stridor)

Fever

Barking cough Hoarseness of voice


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ALTB: Treatment

mild

Reassure parents

Counsel parents re: warning signs

No medication required

Severe

Secure airway

Oxygen

Steroids

epinephrine


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Epiglottitis

Serious, life-threatening deep tissue

infection of upper airway

Rapid diagnosis and treatment necessary 2 - 8 year olds most commonly affected

organisms

H. inftuenzae type B Strep. Pneumoniae

Staph. aureus


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Epiglottitis: Clinical Presentation

Sudden onset respiratory distress over 12 - 24 hrs

Fever

Drooling

Dysphagia Dyspnea

Dysphonia

Little or no cough

Anxious, irritable, toxic-appearing

Voice thick, muffled or hoarse

Some inspiratory stridor


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Epiglottitis: Diagnosis

Clinical impression important

Direct visualization of the epiglottis risky

Manipulation of oropharynx or examinationwith tongue depressor may lead to airway

obstruction

Only if patient cooperative and if immediate

intubation possible


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Epiglottitis: Treatment

Most important: obtain and maintain an

adequate airway

Broad-spectrum antibiotics coveringH.Influenzae until culture results available

Second or third generation cephalosporins

Ampicillin


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Key points

URTIs are common and self limiting

Most URTIs are viral in origin

Air way transmission Common Sx are cough, sore throat, runny

nose nasal congestion, sneezing, muscle

ache, malaise

Antibiotics only target bacteria


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Thank you

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Respiratory Tract Infections 12