Pneumonia clinical Aspect and Rational Treatment

Pneumonia is an infectious process resulting from the invasion and overgrowth of microorganisms in lungs parenchyma, breaking down defenses and provoking intra-alveolar exudates. Consolidation is the term used for the filling of the alveoli with exudate, bacteria and white blood cells which on X-ray appears opaque.  Pneumonia should not be confused with bronchitis which is the inflammation of bronchioles caused by causative agents usually viruses require usually symptomatic treatment.

Classification of Pneumonia types

Pneumonia is usually classified on the base of the place where it occurs. Community acquired pneumonia (CAP) and Nosocomial pneumonia (which is Hospital acquired pneumonia (HAP)).  Both  these term quite define the factors which are causing them. Clinically pneumonia is divided on the anatomical distinctions like Lobar Pneumonia and Bronchopneumonia.

Lobar pneumonia is typical (which mean it is usually acute bacterial infection) of a part of a lobe, entire lobe or even two lobes of the one or both lungs. Clinical features of the lobar pneumonia is that lobar pneumonia is sudden (typical). The clinical majors symptoms are shaking, hemoptysis some times, pleuratic chest pain, consolidation on X-ray, fever, dyspnea and in severe cases mental confusion due to hypoxia, tachycardia and clubbing.   The blood cultures are positive in about 30% of the cases. Lobar pneumonia which is usually caused by pneumococci present with rust color sputum which is indication that Streptococcus pneumonia is the causative agent.

Lobar pneumonia usually occur in Community and is associated with Community acquired pneumonia. Which is usually a typical one. Community acquired pneumonia is differentiated from the hospital acquired pneumonia because the culprits (germs) associated with the hospital acquired pneumonia are nasty one. They are usually resistant and also those agents cause hospital acquired pneumonia which are opportunistic in nature. Just like fungi rarely cause pneumonia in people of community but it would affect immunocompromised people like HIV and other on immunosuppressant therapy in hospital. Burkholderia  Cepacia with usually highly resistant is now a day seen in people other then cystic fibrosis causing pneumonia.

Bronchopneumonia on the other hand is atypical (with usually slow onset) not sudden, that’s why it is called atypical. It usually occur in the extremes of age like infancy or old age above 65. It affect the entire lungs and the X-ray shows patches of opacity chiefly in the lower zones of lungs. In bronchopneumonia there are bed initially low symptomatic onset not acute. Initially bronchitis like symptoms occur followed by symptoms like lobar pneumonia.

Viral Pneumonia is also atypical which occur due to presence of viruses which are common in nasal cavity and upper respiratory tract. Viruses included are like Cytomegalo -Virus (CMV), influenza virus, rhinovirus, parainfluenza virus, varicella zoster virus etc. viral pneumonia is interstitial pneumonia which usually cause infection is the interstitial lining of the lungs. Chest X-ray shows patchy appearance all over the lung. Viral pneumonia is self limiting but some time bacteria may reside worsening the problem. In simple viral case symptomatic treatment is required.

Bacteria which cause pneumonia included are Gram positive agent included Streptococcus pneumonia , staphylococcus areaus usually MRSA      which reside our respiratory lining particular nasal cavity,  gram negative, klebsiella pneumonia,  E. coli, Pseudomonas aeruginosa, Legionella Pneumophilia and others like Mycoplasma pneumoniae.

Lobar and Brnachopenumona (lobular pneumonia) and Interstetial Pneumonia

Diagnosis

Sputum cultures in pneumonia caused by pneumococci and H. influenza is  unreliable because of the presence of pneumococci and H. influenza in the oral secretions, and when sample of sputum is taken it is usually contaminated with oral agent confusing the case whether it is from oral muscoa or from lungs. A more sensitive techniques and lavage techniques are followed for the culturing like Broncho lavage and bronchoscopy. Lavage fluid taken carefully without oral contamination is best for culturing for diagnose.  Legionella may be diagnosed with the urine antigen test. Viruses by PCR techniques and other bacteria by serological convalescent antibody testing. Chest x-ray is also done showing opacity showing pneumonia without the cause or etiology.

Differential diagnosis is necessary from bronchial edema, bronchitis, lungs cancer and COPD etc. it is be easily differentiated through history , Chest x-ray culturing and serology.

Treatment For Community acquired Pneumonia

Outpatient management
Most cases of the pneumonia are treated with empirical treatment. If the condition is worsening or if the patient condition is bad then it is necessary to cultures along with initial empirical treatment.  

Ø    1) For previously healthy patients who have not taken antibiotics within the past 3 months:

Ø .A macrolide (clarithromycin, 500 mg orally twice a day; or azithromycin, 500 mg orally as a first dose and then 250 mg orally daily for 4 days, or 500 mg orally daily for 3 days), or

Ø    Doxycycline, 100 mg orally twice a day.

Ø   2.) For patients with such comorbid medical conditions as chronic heart, lung, liver, or kidney disease; diabetes mellitus; alcoholism; malignancy; asplenia; immunosuppressant conditions or use of immunosuppressive drugs; or use of antibiotics within the previous 3 months

Ø     (in which case an alternative from a different antibiotic class should be selected):

o   A respiratory fluoroquinolone (moxifloxacin, 400 mg orally daily; gemifloxacin, 320 mg orally daily; levofloxacin, 750 mg orally daily) or

Ø     .A macrolide (as above) plus a beta-lactam (amoxicillin, 1 g orally three times a day; amoxicillin-clavulanate, 2 g orally twice a day are preferred to cefpodoxime, 200 mg orally twice a day; cefuroxime, 500 mg orally twice a day).

Ø     3.In regions with a high rate (> 25%) of infection with high level (MIC ≥ 16 mcg/mL) macrolide-resistant Streptococcus pneumoniae, consider use of alternative agents listed above in (2) for patients with comorbidities.

Ø         Similar strategy is followed for inpatients who are not on intensive care units.

Treatment of Hospital acquired Pneumonia which is usually cause by bacteria with Multi-Drug Resistance (MDR) is usually a separate thing to deal with need broad consideration. So is not the choice for this topic. Usually more then one antibiotic is selected up to 3 antibiotics. Hospital acquired Pneumonia sub time ventilator acquired pneumonia (VAP) which is the pneumonia which occur due to contact with the ventilator in ICU or hospital setting. To prevent a non systemic absorbing agents like colistin and Tobramycin but this stretagey may induce drug resistance for the last resort like Colistin for which among gram negative culprit multidrug resistance bacteria.  
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                                     References from 

1. Current Medical Diagnostics 2018 (for Treatment) 
2. Clinical Pharmacy and Therapeutics By Roger walker 5th edition 
3. Text book of Pathology By Harsh Mohan 6th edition