Upper and Lower Respiratory Tract Infection

Infections of the Respiratory tract Most common entry point for infections Upper respiratory tract nose, nasal cavity, sinuses, mouth, throat Lower respiratory tract Trachea, bronchi, bronchioles, and alveoli in the lungs

Throat swab culture A plain cotton wool swab should be used to collect as much exudates as possible for tonsils, posterior pharyngeal wall and other area that is inflamed.

To contributes better results If cooperated by patient, the swab should be rubbed with rotation over one tonsillar area of the soft palate, uvula, the other tonsillar area and finally the posterior pharynx.

Good lighting conditions should be ensured and use of a disposable wooden spatula or tongue depressor to pull outwards and so depress the tongue.

The swab should be replaced in its tube with care not to soil the rim. If it cannot be transported it should be placed in refrigerator at 4C until delivery to lab.

take the swab under sterile condition, rotate it on the first quadrant of blood agar plate

then do the streaking method by loop and stab it few times, then incubate at 37 c / 24 h. Search for hemolytic ß hemolytic: Clear zone. Streptolysin S Streptolysin O (v. imp)

Streptococcus pyogenes Colonies of Streptococcus pyogenes on sheep blood agar. Notice: * Presence of beta hemolysis around colonies * Enhanced hemolysis around stabbing sites * Sensitivity to bacitracin (Disk A)

Streptococcus pyogenes Pin point colony: (white or gray) Gram stain: G+ve, cocci, single chain. Catalase enzyme: differentiate between Streptococcus –ve Staphylococcus +ve

Streptococcus pyogenes Antibiotic susceptibility of S. pyogenes. Bacitracin Sensitive Optochin Resistance

Haemophilus influenzae Facultative anaerobic, Gram-negative coccobacilli small short-rod, pleomorphism, nonmotile

“ Blood-loving ” 35- 370C, 5-10% CO2 X-factor : heat-stable substance ; Hemin or Hematin . V-factor : heat-labile vitamin-like substance. Both X and V factors are found within RBCs.

“ Blood-loving ” BA CA X-factor Heating X, V-factors Release V-factor inactivate NADase X, V-factors

Haemophilus influenzae G-negative coccobacilli, Grayish mucoid colonies on chocolate agar  

Haemophilus influenzae Shows phenomena Satellitism: growth on blood agar near a line of Staphylococcus aureus.

Haemophilus influenzae

Corynebacterium diphtheriae G+ve non motile, pleomorphic rod. Formation of pseudomembrane covering the mouth & pharynx. Can be severe and sometimes fatal disease.

Lower Respiratory Tract Infections Sputum Examination: Sputum: Trachiobroncial secretions, visco-elastic (95% water and only 5% solids) as it comes out, it is contaminated by nasal and salivary secretions and normal bacterial flora of the oral cavity.

Specimen collection In case of Adult: 1- mouth should be pre-rinsedremove contaminants. 2- first morning specimen, Good specimen <10 epith and >25 WBCs.

In case of children Nasopharyngeal swab. Cough Swab method. 1- the child mouth is held open by using tongue depressor. 2- Epiglottis is visualized and is touched with swab to induce cough.

3- Material expelled deposited on the swab and cultured in three different media. * Blood media. * Chocolate. * MacConcy.

Macroscopic Examination Consistency and Appearance. normal sputum is clear and watery. Color of Sputum: Normal color is clear and colorless.in case of infections

Color of Sputum yellow (indicates pus and epithelial cells)=pneumonic+ Staphylococcus aureus.  Green (pseudomonas)== Otitis.  Red (blood) TB.

Microscopic Examination Mycobacterium tuberculosis Acid fast bacilli

Mycobacterium tuberculosis Culture on Lowenestein-Jensen media. Yellowish colony on green background

Streptococcus pneumoniae Lancet-shaped, G-positive diplococci, typical of S. pneumoniae

a hemolysis on 5% sheep blood agar, S. pneumoniae a hemolysis on 5% sheep blood agar, typical of S. pneumoniae. Sensitivity to optochin is also demonstrated

Klebsiella pneumoniae Colonies of Klebsiella pneumoniae on MacConkey agar, showing lactose fermentation and mucoid appearance

IMViC reaction of K. pneumoniae: - - + +

Pseudomonas aeruginosa Greenish discoloration of media due to production of pyocyanin by Pseudomonas aeruginosa

Pseudomonas aeruginosa Results of oxidase test

Paragonimus westermani This lung fluke causes Paragonimiasis. Adult resembles coffee beans Definitive Host Any animal that eats crustaceans Intermediate Host 1st = Snail 2nd = Crustaceans (ex. Crabs)

Paragonimus westermani Life Cycle

Paragonimus westermani Egg Adult

Paragonimus westermani Metacercaria Cyst in Lung

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