Treatment of Bacterial Respiratory Tract Infections PDF

Medicine and surgery Respiratory pharmacology Lecture : (Treatment of bacterial respiratory tract infections) Dr : (Neimt A. Yassin) Date : 11/11 /2024  The respiratory tract is divided into upper and lower parts: the upper respiratory tract consists of the sinuses, middle ear, phary...

Medicine and surgery Respiratory pharmacology Lecture : (Treatment of bacterial respiratory tract infections) Dr : (Neimt A. Yassin) Date : 11/11 /2024  The respiratory tract is divided into upper and lower parts: the upper respiratory tract consists of the sinuses, middle ear, pharynx, epiglottis and larynx, whereas the lower respiratory tract consists of the structures below the larynx, the bronchi, bronchioles and alveoli.  PNEUMONIA Pneumonia is infection of the lung parenchyma (alveoli, distal airways, and interstitium). The alveoli fill with bacteria, inflammatory cells and fluid in a process called consolidation. Mild pneumonia can be treated in the community, but patients with moderate to severe disease will require hospital admission.  Types of Pneumonia 1. Community-acquired (CAP) Typical Atypical Aspiration 2. Nosocomial or hospital-acquired. Early onset Late onset Ventilator associated  ETIOLOGY TYPICAL ATYPICAL S. pneumoniae M. pneumoniae H. Influenzae C. pneumoniae S. aureus Legionella spp. K. pneumoniae Respiratory P. aeruginosa viruses Antibiotic Mechanisms of Action Alteration of Cell Membrane Polymyxins Bacitracin Neomycin Transcription Translation Translation  Types of Antibiotics Cell wall inhibitors: Penicillins Cephalosporins Monobactam antibiotic Vancomycin  Class Drugs Drug of Choice Toxicity Penicillin G Procaine penicillin G Hypersensitivity Penicillin Benzathine penicillin Gram +ve bacteria reaction G Above + Ampicillin Aminopenicillins ↑ Gram-negative: Above Amoxicillin E. Coli Above + Methicillin Penicillinase- PCNase- Above + Nafcillin resistant-penicillins producingStaph. Interstitial nephritis Aureus Above + Antipseudomonal Piperacillin Pseudomonas Above Penicillins aeruginosa  Protein synthesis inhibitors: Tetracycline. Aminoglycosides (e.g. gentamycin) Treat serious infections caused by gram- negative aerobic bacilli. Macrolides (e.g clarithromycin) Used to treat serious infections caused by gram-positive aerobic bacilli Linezolid  Others: Sulfonamides Trimethoprim Drugs that inhibit folic acid synthesis Fluoroquinolones (e.g. ciprofloxacin, moxifloxacin) Inhibit DNA synthesis.  Empirical treatment of community-acquired pneumonia in patients with no history of penicillin allergy CAP severity Antibiotic of choice Mild Amoxicillin oral Moderate Amoxicillin and clarithromycin i.v. or oral Severe Co-amoxiclav (i.v. until clinical improvement) and clarithromycin i.v. or oral 2nd or 3rd G cephalosporine Atypical Macrolides, Doxycycline Quinolones  Hospital acquired Pneumonia (HAP) Treatment Co-amoxiclav for early HAP. Piperacillin and meropenem for Pseudomonas but do not cover MRSA Vancomycin or linezolid for MRSA  Pneumonia due to anaerobic microorganism (Aspiration pneumonia) Pneumonia caused by aspiration of material from the oropharynx or due to the presence of another lung pathology such as pulmonary infarction or bronchogenic carcinoma. The pathogens include anaerobic and aerobic streptococci, Bacteroides. Treatment Amoxicillin or cefuroxime plus metronidazole Co-amoxiclav, monobactams and carbapenems.  Lower respiratory tract infections Acute bronchitis Treatment consists of analgesia, hydration and comfort measures. If there is bacterial infection: Amoxicillin Doxycycline Chronic bronchitis Amoxicillin or co-trimoxazole  Upper respiratory tract infections (URTIs) Colds and flu Most viral URTIs are mild and self-limiting. rhinoviruses, corona viruses and the influenza viruses. Management is symptomatic Rest, hydration, analgesics and antipyretics  Sore throat or Pharyngitis The most serious cases caused by streptococcus pyogenes (group Aβ- haemolytic streptococcus) which is always sensitive to benzylpenicillin (penicillin G) (or erythromycin/clarithromycin in the penicillin allergic) for 10 Days. Chemoprophylaxis I.M. benzathine penicillin in patients who have rheumatic fever. Continued for 5 years or until aged 20, whichever is the longer period. Otitis media Causative bacteria: Strept pneumoniae: penicillins Haemophilus. influenza and Strept pyogenes: amoxicillin and clavulanic acid. If there is no response to amoxicillin or with penicillin allergy: erythromycin or clarithromycin  Case 1: A 24-year-old woman comes to a clinic with complaints of dry cough, headache, fever, and malaise, which have lasted 3 or 4 d. She appears to have some respiratory difficulty, and chest examination reveals rales but no other obvious signs of pulmonary involvement. However, extensive patchy infiltrates are seen on chest x-ray film. Gram stain of expectorated sputum fails to reveal any bacterial pathogens. The patient has no history of serious medical problems. The physician makes an initial diagnosis of community-acquired pneumonia caused by atypical bacteria.  1. Regarding the treatment of this patient, which of the following drugs is most suitable? a. Amoxicillin b.Clindamycin c. Doxycycline d.Flucloxacillin e. Vancomycin 2. A 5-days course of treatment for community-acquired pneumonia would be effective in this patient with little risk of drug interactions if the drug prescribed were a. Ampicillin b.Azithromycin c. Clindamycin d.Erythromycin e. Vancomycin  Case 2: A 34-year-old pregnant woman developed severe pharyngitis that turned out to be due to Streptococcus pyogenes. Past history of the patient was significant for an anaphylactic reaction (allergy) to ampicillin. Which of the following antibiotics would be most appropriate for this patient? a.Amoxacillin b.Ceftazidime c.Imipenem d.Erythromycin e.E. Doxycycline  Case 3: A previously healthy 3-year-old child was admitted to the hospital with sore throat, fever, chills, painful swallowing, and dyspnea for the past 10 hours. Physical examination revealed a seriously ill patient with edematous erythema over the anterior neck, cervical lymph node enlargement, crackles in the left lung base, and diffuse wheezing best heard as stridor over the neck. Sputum Gram stain showed numerous gram-negative bacilli (haemophilus influenzae). A diagnosis of acute pharyngitis was made, and an emergency therapy was started. Which of the following drugs would be most appropriate for the patient’s disease? a. Dicloxacillin b.Penicillin G c. Ceftazidine d.Vancomycin e. Doxacycline  Case 4: A 4-year-old boy was brought to the pediatrician by his mother because of respiratory difficulties. Medical history of the boy was significant for recurrent pulmonary infect ions. A Gram stain of the sputum revealed gram-positive cocci in grapelike clusters (staph. aureus). Which of the following drugs would be an appropriate empiric treatment at this early stage? a.Penicillin G b.Ampicillin c.Piperacillin d.Dicloxacillin e.Amoxicillin  Case 5: A 7-year-old girl was admitted to the emergency department with fever (38.8°C) and a productive cough of thick, greenish sputum. Her medical history was significant for cystic fibrosis and several episodes of pneumonia over the past 3 years. Gram stain of the sputum revealed gram-negative rods (pseudomonas). Growth of bacteria on agar culture exhibited a blue-green pigment. Which of the following β-lactam drugs would be appropriate to include in the therapeutic regimen of this patient? a.Piperacillin b.Cephalothin c.Amoxicillin d.Oxacillin e.Penicillin G