Section I

Organisms causing Upper respiratory tract infections

I. BATERIA: Streptococcus

pyogenes H. influenzae type b C. diphteriae Streptococcus

pneumonae Bordetella

pertussiss Fusobacteria&

Borrelia

DISEAESE:

Pharyngitis & tonsillitis

Epiglottitis- sinusitis- otitis mediaDiphteria

Sinusitis & otitis media Whooping cough

Vincent’s angina

Organisms causing Upper respiratory tract infections

II. VIRUSES

Rhinoviruses

Coronaviruses

Adenoviruses

Parainfluenza virusesEnteroviruses

DISEASESCommon coldCommon coldAcute febrile pharyngitis & Pharygoconjuctival fever

Organisms causing Lower respiratory tract infections(Pneumonia)

I.Bacteria-Strept. Pneumonae-Staph. Aureus-H. Influenzae-Moraxella catarrhalis-Mycobacterium tuberculosis(T.B)-Gram –ve bacilli

-Primary atypical pneumonia:

1- Mycoplasma pneumonae2- Chlamydia(psittaci,trachomatis,pneumonae)3- Coxiella burnetti (Q fever)4-Legionella pneumophila

Organisms causing Lower respiratory tract infections(Pneumonia)

II. VIRUSES- Influenza type A, B

virus-Respiratory Syncytial virus-Parainfluenza virus- Adenovirus- SARS CoV

III.FUNGI- Asperigillus

fumigatus- Candida albicans-Pneumocystitis jiroveci

Streptococcus pneumoniae Gram positive capsulated diplococci.

Laboratory diagnosis of lobar pneumonia

Specimens : Sputum (pneumonia ) CSF (meningitis) Blood (bacteremia)

Gram smear of sputum from a case of pneumonia

Culture :on blood agar ,incubated aerobically for 24 hours.

Gram stained film:Gram positive diplococci

Tests used to differentiate pneumococci ,Viridans streptococci Streptococcus pneumoniae

Optochin sensitivity test sensitive.

Bile solubility test positive .Inulin fermentation positive.Viulence in mice positive.

Alpha haemolytic colonies of Streptococcus pneumoniaeOptochin sensitive.

Streptococcus pnuemoniae

Optochin sensitive

Typing of PneumococciCapsular swelling test: 83 serotypes . The type of pnuemococcus is determined by its reaction with type specific sera .

Questions: What are the diseases produced by

Pneumococcus? How can you diffrentiate betweem

Pneumococci & Strept. Viridans?

Corynebacteria

Non pathogenic i.e, diphtheroidsNormal flora of URT

Pathogenic C.diphtheriae

Toxigenic Non-Toxigenic

Laboratory diagnosis of Diphtheria: Specimens: Throat swab Gram stained smearIt should be differentiated from other causes of pseudomembrane on the tonsils:a) Diphteria : Gram +ve

bacilli ,clubbing, intracellular granules, chinese letter writings “ –ve results are common”

b) Vincent’s angina:large numbers of fusiform bacilli and Borrelia vincenti.

c) oral thruth: Gram positive oval bodies of Candida albicans

d) Acute tonsillitis: Gram positive cocci in chain

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Neisser’s stain: to detect metachromatic granules.

Culture: A) Loeffler’s

serum slope:Enriched medium to demostrate morphology of C.diphterae.3 parts serum+ one part glucose brothSterilized by INSIPISSATION (70-80 C) for 2 hrs for 3 successive days

Mc leod’s tellurite plate:

A selective medium for C.diphterae- Bood agar +

potassium tellurite- Inhibitory

substance: Potassium tellurite

As it inhibits other org. allowing only growth of C. diphterae, appears as BLACK colonies- (reduces tellurite

to black tellurium)

Blood agar plate:

Strept.pyogenes ( acute tonsillitis)

Incubate & examine Loeffler’s serum

slope:

Gram stained film

Typical morphology

Mc leod’s tellurite plate:

BLACK colonies

Blood agar plate:

Beta haemolytic Strept. if the case is:- acute tonsillitis or- Combinecinfection ( diphteria & tosillitis)

Toxigenicity test A) Eleck’s test:

b) ELISA: Toxin detection.

c) PCR : Toxin gene detection.

Laboratory diagnosis of suspected carriers: Specimen :nose and throat Swabs

Pottasium tellurite

Loeffler’s serum slope

Gram stained film & Toxigenicity tests