click below
click below
Normal Size Small Size show me how
RS Microbiology
Respiratory System Microbiology - Bacteriology
Question | Answer |
---|---|
What are the conditions required for infection of the respiratory system to occur? | 1) Sufficient number of infectious agent 2) The agent must be viable and alive in the air 3) The organism must be deposited on susceptible respiratory mucosa 4) Agent must overcome the immune system |
Common normal bacteria flora: | Viridans Streptococci ( S. mutans, S. mitis), Neisseria (N. flava, N. sicca) Haemophilus /Parahaemophilus , Corynebacteria, Anaerobic Bacteria (Bacteroides fragilis, Spirochities) |
Less common bacterial flora: | Group A streptococci , H. influenzae, S. pneumoniae, Candida ,certain Gram-ve bacilli & other bacteria |
What are the characteristics of H. Influenza type B? | 1) Capsulated 2) Lipopolysaccharides 3) Invasive 4) Killed rapidly |
What are the clinical features of H. influenza? | 1) Otitis media, 2) Sinusitis 3) Conjunctivitis 4) Blood sepsis/ Meningitis |
Clinical features of staph aureus: | 1) Sinusitis 2) Pneumonia 3) Conjunctivitis 4) Blood sepsis 5)Staphylococcal pneumonia is a frequent complication Infants, Elderly & immunosuppressed patients |
Characteristics of streptococcus: | 1) Gram-positive cocci 2) Catalase-ve 3) Human commensals & opportunistic pathogens reside Respiratory Tract |
Definitive identification of hemolytic streptococci types based on the serologic reactivity of: | Cell wall polysaccharide antigens (Lancefield groups) |
The most important serogroups are: | A, B,C D, G, F |
Group A Hemolytic Streptococcus (S.pyogenes) cause about 10% of: | Pharyngitis-Tonsillitis/Sore Throat |
Comolication of Group A S. pyogenes: | Post-streptococcal diseases |
Group A causes what reaction? | Beta hemolytic reaction on blood agar |
Between 5-15% of normal individuals carry which bacterium? | Group A hemolytic |
Pathogenesis of group A: | Ability to colonize and rapidly multiply and spread in host due to its hyaluronic acid capsule + cell surface composed of T, R, M-proteins Resistance & Immunity to infection developed by presence of specific M-protein antibodies |
Infection may spread to other body sites like in: | Common sinusitis, otitis, blood sepsis Repeat Streptococcal Throat infection is common in young children each 1-3 months |
Scarlet fever in children begins as: | Pharyngitis |
Scarlet fever causes diffuse erythematous rash in: | Oral mucous membranes |
What is pyoderma? | Superficial localized blisters (impetigo) associated with massive brawny edema |
Cellulitis /Erysipelas may cause: | Glomeronephritis |
Streptococcal Toxic Shock Syndrome symptoms: | High fever, Diarrhea, Shock & Organ failures Highly fatal |
Necrotizing fasciitis results from: | Wound infections |
What are the consequences of Necrotizing fasciitis: | Rapid & extensive necrosis in subcutaneous tissues & fascia Endocarditis, Heart failure High fatality without rapid antibiotics treatment Puerperal fever .. blood sepsis (caused mostly Group B Streptococcus) -neonatal sepsis. |
Post streptococcal diseases: | Rheumatic fever & Glomerulonephritis: followed repeat throat infection |
How is diagnosis of these bacteria done? | Culture on sheep blood agar Hemolytic Strept. Type confirmed by using specific antistrepococcal sera by slide agglutination test Detection Specific Antibodies: 2-4 weeks after throat or skin infection Antistreptolysin 0 (ASO) titer > 240 IU |
Treatment of Group A streptococci: | Penicillin Monthly injection for children: cotrimoxazole |
Clinical features of infection with Corynebacterium diphtheriae, C. ulcerns: | 1) Sore Throat 2) Intensive inflammation pharyngeal mucosa 3) Myocarditis 4) Peripheral nervous system/ Neuritis 5) Adrenal glands 6) Laryngeal obstruction 7) Respiratory & Heart Failure |
Is there a vaccination for Corynebacterium diphtheriae, C. ulcerns? | Yes Provides permanent immunity |
Lab diagnosis is done by: | 1) Throat swab 2) Culture for C. diphtheria 3) Selective Tellurite Blood agar 4) Toxin test |
Vincet Angina/Trench Mouth is caused by: | Mixed infection of Oral flora Borrelia /Treponema vincenti/ Fusobacterium |
Consequences of Vincet Angina/Trench Mouth: | Oral mucosa Lesions/ Gingivitis |
Lower respiratory tract infection may mainly lead to which pathology? | Pneumonia |
The patient become more susceptible to LRT infection by presence of: | COPD |
Common incidence of LTRIs among: | Infant ,Old age, and immunocompromised |
Acute bronchitis and bronchiolitis is: | A clinical syndrome caused by inflammation trachea, swelling & irritation of bronchi & bronchioles |
General symptoms of bronchitis: | 1) Persistent dry cough 2) Few sputum |
What is the most common lower respiratory tract infection in infants? | Bronchiolitis |
Acute bronchitis in children is caused by | Viral agents and later increased by bacterial infection(B. pertussis, Ch.pneumoniae & My.pneumoniae) |
Acute & Chronic bronchitis in Adults follow: | Viral infections/directly Associated with Strept. pneumoniae, H. influenzae, Group A Strept., S. aureus |
Complications of Acute & Chronic bronchitis in Adults: | Caused by asthma |
Whooping cough and bronchitis is caused by: | Bordetella pertussis /B. parapertussis: Release Endotoxins and Cytotoxins Attachment & obstruction of ciliated epithelium cells of small bronchi |
Clinical features: | 1-Catarrhal stage: Mild cough, & inflammation pharynx-Larynx, Low fever, Bronchitis 2-Paroxysmal cough: Prolonged irritating Cough, Mucus secretion, Fever, Cyanosis, Lung collapse, Convulsions, Mostly infect Young children |
Clinical Diagnosis of whooping cough: | Laboratory test by PCR for detection bacterial DNA in nasopharyngeal swab Specific antibodies in blood & Urine |
Mild Pneumonia is: | Inflammation of the lungs Fever Sputum |
Severe pneumonia is: | Bacterial Lung Inflammation Pleural effusion /fluid buildup Breath shortness Purulent sputum High Fever Malaise Nausea Vomiting Increased heart rate Mental confusion |
Pneumonia categorized into: | 1) Community-acquired pneumonia (CAP) 2) Hospital- acquired pneumonia (HAP) |
CAP mostly caused by: | Strep. pneumoniae (80%) & followed viral infection in children & elderly patients |
HAP caused by: | Gram-ve P. aeruginosa, Klebsiella pneumonia, Acinetobacter baumannii Less by Haemophilus influenzae type b, S. aureus or others |
Pneumonia is normally found in the nasopharynx of: | 5-10% of healthy adults 20-40% of healthy children |
Virulence factors of Streptococcus pneumonia: | Polysaccharide capsule & Pneumolysins Both resist phagosytosis & host's immune system Released Proteases damages mucosal IgA |
S.pneumoniae starts as: | Intrapulmonary abscess.. Lung necrosis Often associated with Empyema More associated with Blood sepsis, Meningitis, Sinusitis, Otitis Media in young children than adults |
Lab diagnosis for S. pneumonia: | Gram-positive diplococci can be differentiated from S.viridans, which is also alpha hemolytic on Blood agar by Optochin / bile solubility tests |
Treatment of S. pneumonia: | Amoxycillin-clavulanate, Macrolides (Azithromycin, clarithromycin), Fluoroquinolones (Levofloxacin, ciprofloxacin) For Bacteremia +meningitis, vancomycin,ceftriaxone /cefotaxime |
Prevention of pneumonia by: | 23-valents vaccine (pneumovax) One dose for adults Protection 1-2-years 13- valent vaccine (Prevnar) 3 doses for children Up to 2-year high protection |
Which bacteria can cause sinusitis? | H. influenza Staph. Aureus Group A Strep Strep. Pneumoniae |
Which bacteria can cause otitis? | H. influenza Group A Strep Strep. Pneumoniae |
Can pneumonia be prevented by vaccine? | Typical can Atypical can not |