PNEUMONIAS

PNEUMONIAS

PROF. Dr. Abdul Hameed Al Qaseer

Definition:

Pneumonia may be defined as an inflammation of the substance of the lung ; lung parenchyma ( the alveoli, distal airways,& interstitium of the lung). Clinically it presents as an acute respiratory illness characterized in the majority of cases by the presence of cough ,purulent sputum ,& fever together with physical signs or radiological changes compatible with consolidation of the lung.

RESPIRATORY ZONE

Impact of CAP
Affects 2-3 million people annually 20-25% require hospital admission CAP is the number one cause of death from infectious diseases The 6th leading cause of death in the USA Overall mortality is 13.7%, < 1% for those not requiring hospitaliztion Incidence is increasing: aging population and continued smoking in the young Bartlett. CID 1998;26:811-38.

Host Defenses Protecting The Lung :

1. Innate( nonspecific) a. anatomical features of the URT ; the nasal turbinate ,&the sharp angle , & the glottis . b. the mucociliary transport system +IgA . c. The cough reflex . d. In the LRT fibronectin, lysozymes ,lactoferrin,IgG & IgD ,& complements . e. The macrophages 2. Acquired ( specific ) This required T- cell activation Lymphocytes ,mononuclear phagocytes with macrophages are present to ensures a fast response of immunoactivation.

Factors In Pathogenesis Of Pneumonia :

Route of infection: For pneumonia to occur , potential pathogen must reach the LRT in sufficient numbers or with sufficient virulence to overwhelm host defenses. 1. Gross aspiration : can occur postoperatively & in pat. with CNS disorder that affect swallowing ( e.g. strokes,siezures) 2.Microaspiration of oropharyngeal secretions : It is the most common route . 3. Hematogenous spread : e.g. infective endocarditis ,I.V. catheter. 4. Aerosolization :e.g. pul. TB ,fungi ,& respiratory viruses.


Microbial Factors:
Pathogenic microorganisms have developed a variety of mechanisms to counteract host defenses e.g. Chlamydia pn. produces a ciliostatic factors Mycoplasma pn. Can shear of cilia Strept. Pn. produce protease that can split secretary IgA . Mycobacterium & Legionella spp. Are resistant to the microbicidal activity of phagocytes.

Classification Of Pneumonias:

There are several ways of classification :Pathological classification a.lobar b. bronchopneumonia c. interstitial d. miliary Clinical classification a. typical b. atypical Etiological classification a. viral pn. b. pneumococcal pn. c. mycoplasmal pn. ……………Epidemiological classification a. community acquired pn. (CAP) b. nosocomial pn. c. pneumonia in immunocompromizes pat.

ATS classification of Pneumonia

What is Health Care- Associated Pneumonia(HCAP)? 
Over the past two decades , some persons presented as outpatient with onset of pneumonia have been found to be infected with multidrug- resistant (MDR) pathogens previously associated with HAP Factors responsible for this phenomenon include:The development& widespread use of potent oral antibiotics .Hospitalization for 2 days or more within the past 90 days .Earlier transfer of patients out of acute –care hospital to their homes.Increased use of outpatients I.V. antibiotic therapy.Wound care within the past 30 days .Attended hemodialysis clinic .General aging of the population .More extensive immunomodulatory therapies.

Community acquired pneumonia (CAP)

CAP affects about 4 million adults per year in US,~ 20% of whom are admitted to a hospital .The overall rate of pneumonia range from 8-15 / 100,000 persons /year . UK figures suggest that an estimated 5-11/100,000 adults suffer form CAP each year. Factors that predispose to pneumonias Cigarette smoking Old age URT infection Alcoholism Corticosteroid therapy Recent influenza infection Pre-existing lung disease Immunosuppression

Etiology of CAP :

There are > 100 documented microbial causes of CAP include bacteria ,fungi ,viruses , & parasites . Fortunately ,most causes of pn.caused by a few common respiratory pathogens including strept. pneumonia ; H. influenzae ;Staph. aureus ; Mycoplasma pn. ; Chlam. Pn. ; Moraxella catarrhalis ;Leg.spp. ;aerobic gram-negative bacteria . Influenza viruses,adenoviruses ,& RCV . The relative frequency of these pathogens differs with age & severity of pn. Overall strept. pn. accounts for ~ 50% of all cases of CAP requiring admission to hospital .



Macroscopic pathology
Heavy lung Congestion Red hepatisation Grey hepatisation Resolution The classical pathway

Pneumonia – fibrinopurulent exudate in alveoli

Pneumonia – neutrophil and macrophage exudate (grossly “grey hepatisation”)

Clinical Features Of Pneumonia

Pneumonia typically presented as an acute illness with fever , rigors & shivering . Pul. Symptoms include cough ( short, painful ,dry) , but later the sputum become mucopurulent.or purulent, rusty ( pneumococcal pn.) .& occasionally hemoptysis. Pleuritic chest pain may be a presenting feature & occasionally may referred to the shoulder or the upper abdomen .Breathlessness may be a prominent feature especially in severe cases. Other symptoms nausea ,vomiting ,diarrhea , myalgia, arthralgia &/or fatigue . Altered consciousness & confusion may be important manifestation in an elderly . The term atypical pneumonia has recently been abandoned.

CLINICAL PICTURE OF PNEUMONIA

Signs and Symptoms of Pneumonia (common): 1-Fever 2-Cough (productive or nonproductive) 3-Pleuritic chest pain 4-Chills 5-Shortness of breath Other Symptoms: Headache Nausea Vomiting Diarrhea Myalgia Arthralgia Fatigue Anorexia Respiratory complaints (rales and/or rhonchi) Sweats Purulent tracheal secretions

Physical examination :

The patient is acutely ill with tachypnea , febrile , increased tactile & vocal fremitus ,dullness to percussion ,egophony whispering pectoriloquy, crackles , bronchial breathing ( lobar consolidation), pleural rub may be heard ,& pleural effusion may be present.

Differential Diagnosis :

Pul. Infarction. Pul./pleural TB . Pul. edema . Pul,. eosinophilia . Malignancies (bronchoalveolar cell ca. ). Rare disorders e.g.cryptogenic organizing pneumonitis . Vasculitis .

Diagnostic Evaluation

CXR: Lobar vs. Bronchopneumonia, Effusion, Cavitation. Sputum Gram stain: >25 PMN and < 10 epithelial Sputum Culture Blood culture: +ve in ~ 15% CBC BUN / Cr ABG / oximetry Serologic testing: not too helpful in CAP Bronchoscopy HIV: risk factors, 15-54years of age

Investigations :

Radiological examination ; a. In lobar pn. , a homogeneous opacity localized to the affected lobe or segment usually appears within 12- 18 h from onset. b. In bronchopneumonia , a nodular shadows usually in the dependent region & may be bilateral. c. Interstitial pn. shows reticular or reticulonodular shadow usually widely distributed. d. Miliary shadow e.g. viral or TB ……. CXR may shows pleural effusion , or lung abscess , or cavity.

PA view consolidation of the right middle lobe

Lateral view

Pneumococcal pneumoniaCT

Microbiological Investigations:
1.Sputum – direct Gram & Ziehl-Neelsen stains. Culture & sensitivity testing.2. Blood culture .3. Serology _ for Mycoplasma, Chlamydia ,Legionella & viruses. Pneumococcal antigen.4. General blood tests : WBC > 15 X 10 /L favors bacterial pn. > 20 x 10 /l or < 4 x 10 /l suggest severe pn. Urea & electrolytes & liver function test .

In severe CAP Other Investigations are added

1.Tracheal aspiration , induced sputum, BAL, percutaneous needle aspiration. 2.Serology :Leg.antigen in the urine. Pneumococcal antigen in sputum & blood. Immediate IgM for Mycoplasma. Direct fluorescent antibody stain for Leg.& viruses. 3.Cold agglutinins ( positive in 50% of Mycoplasma). 4. Pleural fluid exam. 5. Pulse oximetry or blood gas analysis.



Assessment of disease severity :
CURB-65 score : C= Confusion U= Urea R= Respiratory rate >30/min. B= Blood pressure( systolic<90mmHg or diastolic <60mmHg ) Age 65 year or more Score 1 point for each feature present o-1 score for home treatment; score 2 consider hospital-supervised treatment . score 3 or more manage in hospital as severe pneumonia. score 4-5 assess for ICU admission.

CURB 65 Rule – Management of CAP

Class
Points
Mortality*
Site of Care
I
<51
0.1%
OutPatient
II
51-70
0.6%
OutPatient
III
71-90
2.8%
In or OutPatient
IV
91-130
9.5%
Inpatient
V
>130
26.7%
Inpatient
Pneumonia Severity Index

Complications Of Pneumonia

1.Para-pneumonic effusion (common). 2.Empyema. 3.Lobar collapse (due to sputum retention). 4.Development of thromboembolic disease. 5.Pneumothorax . 6.Suppurative pneumonia/ lung abscess. 7.ARDS , respiratory failure , renal failure ,multi-organ failure. 8.Ectopic abscess formation. 9.Hepatitis , pericarditis ,myocarditis ,meningoencephalitis. 10. Pyrexia due to drug hypersensitivity. 11. Circulatory failure , septic shock .

Management of Pneumonia

Most patients with pneumonia are treated empirically . The selection of antibiotic therapy depends on the site of care and the presence of risk factors for certain pathogens .

Risk factors for drug resistant

For streptococcus pneumoniae resistance: 1. age > 65 year 2. recent ( within the past 3 months ) B- lactam therapy . 3. medical comorbidities 4. immunocompromisng conditions 5. immunosuppression therapy 6. Alcoholism 7. Exposure to a child in day care.

Management Of Pneumonia :

Antibiotics : If possible , culture & direct sample stain exam. Should be sent before starting antibiotics . The choice of antibiotics is guided by clinical context , & severity . Also it depends on the site of care and the presence of risk factors for certain pathogens. The duration of treatment 7-10 days in uncomplicated CAP . Longer durations is usually required in Legionella, staph.or Klesiella pn.

Antibiotic For CAP

Uncomplicated CAP: - Amoxicillin 500mg 8-h p.o . If pat. Allergic to penicillin Clarithromycin 500mg 12-h p.o. or Erythromycin 500mg/6h p.o. or Doxycycline p.o. - If staph. Is suspected or isolated ; Flucloxacillin 1-2g / 6h IV + Clarithromycin 500mg/12h IV - If Mycoplasma or Legionella is suspected : Clarithromycin 500mg/12h p.o. or Erythromycin 500mg/6h p.o. or iv + Rifampicin 600mg /12h i.v. in severe cases.

In severe CAP:Clarithromycin 500mg /12h i.v. orErythromycin 500mg /6h i.v. + Co- amoxiclav 1.2g/ 8h i.v. or Ceftriaxone 1-2 g i.v. daily or Cefuroxime 1.5 g /8h i.v. or Amoxicillin 1g /6h i.v. + flucloxacillin 2g /6h i.v. OR Respiratory fluroquinolones : ( Moxifloxacin, Levofloxacin,……..


In hospitalized patients , I.V. antibiotic therapy can be change to oral therapy if : 1. temp.< 37.8C 2. PR< 100/min 3. RR < 24/ min 4. BP > 90 mmHg 5. PaSO2 > 90% or PaO2 . 60 mmHg 6. ability to tolerate oral intake 7. normal mental status

2. Oxygen : Oxygen should be given to every pat. With tachypnea , hypoxemia , hypotension , acidosis , & altered consciousness with the aim to keep PaO2 >8 kpa or SaO2 92%. High concentration > 35% humidified , should be given unless hypercapnia is present . 3. Fluid balance: To correct dehydration. 4. Analgesics : To relieve pleural pain in order to allow the pat.to breathe normally and cough effectively . Mild analgesics are rarely adequate ;however ,opiate must be used with caution? 5. Physiotherapy

Criteria for hospital admission of pat.with CAP

1.RR>28/min .2.Systolic BP < 90mmHg .3. Confusion or impaired level of consciousness.4.Hypoxemia PaO2 < 60mmHg or So2 < 90 %.5. Comorbid illness e.g. CHF , uncontrolled DM , immunosuppresion ……6.Multilobar pn.7. Significant pleural effusion .

Failure to improvement despite treatment of CAP:

1. Reconsider the diagnosis . 2. Are you treating the wrong pathogens? 3. Are you using the wrong drugs ? 4. Obstruction of the airway e.g. bronchogenic ca. or foreign body . 5. Have you overlook an undrained or metastatsic pyogenic focus e.g. empyema , endocarditis ,abscess else where. 6.Does the pat. have drug-associated fever . 7. Infected cannula or catheter .

Indication for referral to ITU ( or RCU):

CURB score 4-5 Persistent hypoxia PaO2 < 8 kpa ( 60mmHg) despite high concentration of oxygen . Progressive hypercapnia . Severe acidosis . Shock . Depressed consciousness.

Prevention Of Pneumonia

Vaccination : Influenza vaccine reduces the risk of influenza & death in elderly.Pneumococcal vaccine consist of purified capsular polysaccharide from the 23 Pneumococcal types ( 90%). Vaccination decrease complication by about 50% & reduce the carrier state among the general population . It is recommended for:- 1. >65year 2. DM 3.heart & lung diseases 4. renal insufficiency 5. hepatic insufficiency 6.sickle cell anemia 7. asplenia 8. alcoholism 9.immunodef. +AIDS ……..

Factors predisposing to HAP :

Reduced host defences against microbes: - reduced immune defences - reduced cough reflex - disordered mucociliary clearance - bulbar or vocal cord palsy 2. Aspiration of nasopharyngeal or gastric secretion: - reduced conscious level - vomiting , dysphagia , achalasia or severe reflux - NG tube 3. Bacteria introduced into the LRT: -Endotracheal intubation\tracheostomy - infected ventilators/ nebulisers/ bronchoscopy - Dental or sinus infections 4. Bacteremia: - Abdominal sepsis - IV cannula infections - Infected emboli

Hospital-acquired Pneumonia ( HAP) (Nosocomial Pneumonia)

HAP refers to a new episode of pneumonia occurring at least 2 days after admission to hospital. The definition of HAP includes the presence of a new infiltrate on CXR plus at least 2 of the following : Fever > 37.8 C ( 100F) Leukocytosis (>10,000 WBC /ul) The production of purulent sputum


Aetiology Of HAP
Gram-negative bacteria are the most important pathogens causing HAP e.g. E.coli ,Pseudomonas ,& Klebsiella. Staphy.aureus (including MRSA) are also common,& anaerobic organisms are more likely encountered than in CAP. Clinical Features : In general HAP similar to CAP in its presentations. In the elderly or debilitating pat. who develops acute bronchopneumonia ( or hydrostatic pneumonia ). Symptoms of acute bronchitis are followed by cough & purulent sputum associated with fever . Breathlessness ¢ral cyanosis may then appear. Diagnosis: 1. leukocytosis 2. CXR ( shows mottled opacities in both lung field ,chiefly in the lower zones.).

Management Of HAP:

Third –generation cephalosporin e.g.cefotaxime + aminoglycosides e.g. gentamicin orMeropenem orAztreonam + flucloxacillinAspiration pneumonia can be treated with :Co- amoxiclav 1.2g /8h + metronidazole 500mg/8h .The mortality from HAP is high (~30%).

Suppurative & Aspiration Pn. & Lung Abscess

It is a form of pneumonic consolidation in which there is destruction of the lung parenchyma .Lung abscess It is a localized area of suppuration within lung tissue that leads to parenchymal destruction & is manifested radiologically as a cavity or with air-fluid level. Although mycobacterial, fungal,& parasitic infection can cause cavitary lesions , the term of abscess is reserved for bacterial infection. Risk Factors: Conditions associated with impaired cough reflex & / or aspiration e.g. alcoholism ,anesthesia , epilepsy , stroke…Dental caries , bronchiectasis ,bronchial ca. ,pul. Infarction.

Causes :

1.Staph. aureus or Klebsiella pn. 2.Inhilation of septic material from nose ,mouth ,or throat under GA or vomiting during anesthesia or coma ( more frequently).3. Bulbar or vocal cord palsy .4.Oesophageal e.g. achalasia , GERD …..5. Hematogenous spread 6.Bacterial infection of pul. Infarction or a collapsed lobe .Organisms isolated : includeStrept. pn. , Staph. aureus , Strept. pyogenes , H. influenzae,& in some cases anaerobic bacteria .

Clinical features of suppurative pneumonia

Symptoms: Cough productive ,may be fetid & blood –stained .Pleural pain ( common ).Sudden expectoration of copious amount of foul sputum (anaerobic infection).Signs: High remittent fever .night sweating , malaise ,halatosis.Profound systemic upset & weight lossDigital clubbing ( 10-14 days) in ~ 10% .Chest exam. Usually reveals sign of consolidation ; rarely sings of cavity ; pleural rub is common .

Left upper lobe lung abscess distal to bronchial carcinoma

Differential diagnosis:
1. Cavitating carcinoma. 2. Wagener's granulomatosis. 3. Rheumatoid nodules. 4. Pulmonary infarction . 5. TB 6. Fungal infection .


Management :
Amoxicillin 500mg /6h with or without Metronidazole 400 mg /8h ( anaerobic ) For 4-8 weeks Medical treatment is unsuccessful in ~ 10% . Clindamycin 600 mg /6h I.V. then when the patient is afebrile & improve 300mg /6h is effective. *Physiotherapy is of great values. *Surgery ( in ~ 10% ) e.g. percutaneous drainage or lobectomy .

Complications of lung abscess

Empyema Bronchopleural fistula Asphyxiation due to spillover of pus Brain & distal abscess Pulmonary gangrene

Prognosis

Mortality occurs in 5-10% The prognosis will be worse in: 1. large abscess (> 6 cm) 2. progressive pulmonary necrosis 3. obstructive lesion 4. aerobic infection 5. immune compromise 6. old age ,systemic debility 7. delayed to seek medical attention

Pneumonia In Immunocompromised Pat.

Pulmonary infection is common in immunocompramised pat. The majority of infections are caused by the same common pathogens. However, unusual organisms& low virulence Or non-pathogenic may become ` opportunistic ` pathogens. Infections is often due to more than one organism . Common causes of immunocompromised : Defective phagocytic function : e.g. acute leukemias, cytotoxic drugs , agranulocytosis . Infecting organisms e.g. Gram-positive including Staph. aureus ; Gram-negative; fungi e.g. Candida albicans ,Aspergillus fumigatus .

Infecting organisms e.g. viruses like CMV , HV ,Adeovirus ,Influenza . fungi P.carinii , Candida ,A. fumigatus lymphoma , thymic aplasia.

2. Defects in cell-mediated immunity : e.g. immunosuppressive drugs , cytotxic chemotherapy, lymphoma , thymic aplasia . Infecting organisms : - Viruses e.g. CMV ,HV ,Adenovirus , Influenza viruses . - Fungi e.g. P.carinii ,Candida , A. fumigatus . 3. Defects in antibody production e.g. multiple myeloma , CCL . Infecting organisms : H. influenzae , Mycoplasma pn.