This document provides an overview of respiratory tract infections including anatomy, types, causes, symptoms, and laboratory diagnosis. It describes infections that can occur in the upper respiratory tract like sinusitis, pharyngitis and laryngitis as well as lower respiratory tract infections such as pneumonia, bronchitis and infections of the lungs. Common pathogens that cause respiratory infections are discussed. Methods for sample collection, processing, culture and identification of bacteria and fungi are outlined. Diagnostic tests including microscopy, antigen detection, serology and PCR are also summarized.

1. PRESENTED BY – SHAMIMA RAZIA MODERATOR – Dr. RITU GARG
BSc. MLT III Year ASSISTANT PROFESSOR
MICROBIOLOGY, GMCH-32

2. GENERAL ANATOMY OF RESPIRATORY
TRACT
 NOSTRILS
 PHARYNX
 LARYNX
 TRACHEA
 BRONCHI
 BRONCHIOLES
 LUNGS
 ALVEOLI

3. RESPIRATORY TRACT INFECTION
Respiratory tract infection (RTI) includes
infections of upper respiratory tract and
lower respiratory tract

4. TYPES
Upper respiratory
tract infection
 Infection of middle ear
and sinuses
 Infection of throat and
pharynx
Lower respiratory
tract infection
 Infection of trachea and
bronchi
 Infections of lungs

5. PREDISPOSE TO RESPIRATORY TRACT
INFECTION
 Physical damage, e.g. smoking,etc.
 Loss of defence because of preexisting infectious
disease , immunosuppressive therapy, etc
 Damage to respiratory tract by viral infection

6. ROUTES OF INFECTION:-
 Infection is air borne
 Talking, coughing and sneezing spread the infection
 Air is a potential source of infectious agents for
respiratory infections

7. UPPER RESPIRATORY TRACT INFECTION
Infection of Ear and
Sinuses
 Acute otitis media
 Otitis externa
 Acute sinusitis
Infection of Throat
and Pharynx
 Tonsillitis
 Pharyngitis
 Sore throat
 Laryngitis
 Epiglottitis
 Peritonsillar abscess
 Oral thrush
 Vincent’s angina

8. LOWER RESPIRATORY TRACT
INFECTION
Infection of Trachea
and Bronchi
 Bronchitis
 Bronchiolitis
 Bronchiectasis
 Tracheitis
 Tracheobronchitis
Infection of Lungs
 Pneumonia
 Lung abscess
 Empyema
 Respiratory tract
infection leads to
septicemia and
bacteramia

9. GENERAL SIGNS AND SYMPTOMS
 Fever &chills
 Chest pain
 Malaise
 Nausea & vomiting
 Headache
 Painful cervical lymphadenopathy
 Tonsillitis and Pharyngitis
 Pain on swallowing

10. UPPER RESPIRATORY TRACT
 The commonest respiratory infections are localized in
the oropharynx, nasopharynx and nasal cavity,
causing sore throat, nasal discharge and often fever.
 The upper respiratory tract is frequently involved in
wider or generalized infections such as whooping
cough and measles, infections with mycoplasma
pneumoniae, influenza, parainfluenza, adenovirus.
 The potential bacterial pathogens commonly present
in the nasopharynx e.g. pneumococcus, H.influenzae,
S.aureus and strep.pyogenes.

11. SORE THROAT
Definition :- Sore throat is a condition where the mucus
membrane in the throat is inflamed because of an
infection. Most common disease in young children
caused by bacteria, virus and fungi.

12. PATHOGENESIS
 Droplet inhalation
 Portal of entry is respiratory tract
AGENTS
 Streptococcus pyogenes(group A streptococcus)
 Corynebacterium diphtheriae
 Beta – hemolytic streptococci (group C and G)
 Staphylococcus aureus

13. OTHER BACTERIAL THROAT INFECTIONS:
Haemolytic streptococci other than strep. Pyognes are
present in the throat as harmless commensals, but
those are groups C & G occurring & B rarely cause
pharyngitis.
VIRAL THROAT INFECTIONS:-
Epstein- Barr virus which cause an infectious
mononucleosis , associated with throat lesions,
enlarged lymph nodes, fever, abnormal LFT test.

14. NASAL, ORAL & SINUS INFECTIONS
 The organisms infecting the nasal cavity are mainly
the same as throat infections.
 Nasal swabs are more often taken to detect healthy
carriers then to diagnose infections , deep nasal
sawbs being taken for strep. pyogenes & diphtheria
bacillus.

15. CLINICAL SYNDROME
Sinusitis
Epiglottitis
CAUSATIVE AGENTS
 Strep.pneumoniae,
H.influenzae,
strep.pyogenes,
moraxella
catarrhalis,S.aureus
H.influenzae type B

16. EAR INFECTION
Swabs are taken from the external auditorymeatus
mainly in three suspected conditions acute otitis media,
chronic suppurative otitis media & otitis externa.
• ACUTE OTITIS MEDIA:- The organisms spreads to the
middle ear via the Eustachian tube from the
nasopharynx.

17.  CHRONIC SUPPURATIVE OTITIS MEDIA:- when
the eardrum has been perforated in an acute attack of
otitis meida and remains patent infections with the
original pathogens may persist or repeated infection
may be caused by secondary invaders such as S.aureus,
coliform bacilli, pseudomonas & bacteroids.
 OTITIS EXTERNA:- chronic inflammation of the skin
of the external meatus, with irritation & discharge, may
be caused by bacteria, particutarly pseudomonas
aeruginosa, coliform bacilli, & S.aureus or fungi, are
candida & aspergillus.

18. LARYNGITIS
Definition:- Inflammation or irritation of the tissues
of the larynx. Laryngitis causes a hoarse voice or the
complete loss of the voice because of this irritation to
the vocal folds or cords.

19. LARYNGITIS PATHOGENESIS
 infection
 vocal overuse
 smoking and other inhaled irritants
 drinking of spirits
 contact with caustic or acidic substances (including
acid reflux from the stomach)
 allergic reaction
 direct trauma
 Pseudo membrane formation

20. LARYNGITIS AGENTS
• Influenza viruses
• Rhinoviruses
• Adenoviruses
• Streptococcal infection
• C. diphtheria

21. LOWER RESPIRATORY TRACT INFECTIONS
 Trachea, bronchi & lungs are normally free from commensal
& potentially pathogenic bacteria but when their defeces are
upset they are liable to be invaded by organism.
 They are the site of primary infections witch various inhaled
pathogens, such as tubercle, whooping cough bacilli,
influenzae viruses, mycoplasmaPneumoniae & chlamydias.
 The commonest infections are acute tracheobronchitis,
acute exacerbations of chronic bronchitis & pneumonias.
Most cases the primary infection is caused by a virus e.g.
rhinovirus, adenovirus, myxovirus.

22. CLINICAL SYNDROME
 Bronchitis, bronchiolitis
PNEUMONIA
 Community acquired
pneumonia
CAUSATIVE AGENTS
 Respiratory viruses, myco
plasma pneumonias,
chlamydia pneumonias,
bordetella pertussis.
 Children:- resp. syncytial
virus, parainfluenza virus,
adeno virus,
strep.pneumonia,
H.influenza, Gp.B
streptococci
 Adults:- S.pneumonia,
Mycoplasma pneumonia,
H.influenzae, S.aureus,
GNB, Legionella spp.

23. CLINICAL SYNDROME
 Nosocomial pneumonia
 Aspiration pneumonia
 Chronic pneumonia
 empyema
CAUSATIVE AGENTS
 GNB, Gram +ve org.,
anaerobes, Legionella spp.
 Mixed anaerobes &
aerobes, anaerobes alone
 Mycobacteria, fungi.
 Community acquired:-
S.aureus,
Strep.pneumoniae,
Strep.pyogenes
 Nosocomial:- GNB

24. PNEUMONIA
Definition :-Inflammation of the Lungs with
production of alveolar exudates.
Inflammation and consolidation of the lung
caused by microorganisms.
AGENTS
 Streptococcus pneumoniae
 Klebsiella pneumoniae
 Staphylococcus aureus
 Mycoplasma pneumoniae

25. PNEUMONIA TRANSMISSION
 Droplet inhalation
 Aspiration of upper respiratory tract secretions
containing microorganisms
 Haematogenous or lymphatic dissemination
 Direct contact with respiratory secretions

26. BRONCHITIS
Definition:-Bronchitis is an inflammation of
the bronchial tubes, or bronchi, that bring
air into the lungs. Inflammation is a
chemical reaction in the body that produces
redness, swelling, and pain.

27. TYPES OF BRONCHITIS
 Acute bronchitis
 Chronic bronchitis
PATHOGENESIS
• Disturbed bronchial epithelium
• Excessive fluid accumulation
• Cough variable fever
• Sputum production

28. LABORATORY
DIAGNOSIS

29. (I) SAMPLES :-
 Throat swab, ear swab, nasal swabs are collected in
upper respiratory tract.
 Sputum is most commonly used in lower respiratory
tract.
 Transtracheal aspirates
 Bronchial aspirates
 Pleural fluid
 Blood culture is used in case of pneumonia

30. COLLECTION
THROAT SWAB:-
• The swab should be rubbed with rotation over one
tonsillar area
• The arch of the soft palate and uvula and finally the
posterior pharyngeal wall
• The throat should be ensured good lighting
• The use of a disposable wooden spatula to pull
outwards and depress the tongue
• Swab should be replaced in its tube with care not to
soil the rim

31. SPUTUM
 Collection in a disposable ,wide-mouthed, screw-
capped plastic container
 Collect the sputum before any antibiotic therapy is
begun
 Patient to wait feels material coughed into his throat
and then to spit it directly into opened container
 Sputum should be collected in sterile container to
minimize containing with saliva
 Early morning sputum is more purulent

32. Bronchial swabs and aspirates
 Bronchial collection may be done by transtracheal
puncture aspiration or by the use of protected swab
passed through a bronchoscope into the bronchi
 Direct aspiration of secretion through a
bronchoscope, e.g. by bronchial lavage
Bronchial swabs aspirates machine

33. Blood Culture
In cases of suspected of pneumonia
a sample of blood should be taken for
culture before antiobiotics are given.
Lung infections are commonly
associated with bacteraemia.
Culture from the blood a delicate
pathogen whose growth is suppressed
in cultures of sputum contaminated
with salivary org.

34. TRANSPORT OF SPECIMENS
 Upper respiratory tract infection, specimen is
collected using swab, it should be transported
immediately to lab without delay.
 If delay is expected then specimen should be collected
in a suitable transport media such as Ringer solution
to keep the swab moist
 Sputum should also be transported immediately to
avoid the death of delicate organism like H.influenzae
 If delay is suspected hold the specimen at 4 degree
cellcious.

35. PROCESSING OF SPECIMEN
DIRECT EXAMINATION:
 Gram stain
- Pus cells
-Bacteria – morphology, gram reaction
- Budding yeast cell, hyphae
- gram +ve stain should be cocci, diplococci or
gram neg. bacilli
S.aureus

36. Ziehl Neelsen stain
For mycobacterium tuberculosis.
AFB STAIN

37. India ink preparation
large polysaccharide capsule of
Cryptococcus neoformans, pneumococci,
Candida can be seen, but latex
agglutination testing for capsular Ag
is more sensitive.

38. POTASSIUM HYDROXIDE
PREPARATION (KOH MOUNT)
Use of 20% KOH mount for demonstration of Candida
albicans, aspergillus species, Cryptococcus neoformans.
Cryptococcus neoformans Candida Albicans

39. Other stains are:
Direct wet mount and silver methenamine stain for
pneumocystis carinii
Direct fluorescent antibody test for demonstration of
antigen in specimen
Electron microscopy for demonstration of Chlamydia
and viruses

40. CULTURE
 Bacterial culture –a loopful of specimen is
inoculated on-:
- Blood agar
- Chocolate agar
- MacConkey agar
- Lowenstein Jensen medium{ if ZN is positive}
- Brain heart infusion broth
 Plates are incubated at 37°C in an incubator for 24 hrs.
 On Chocolate agar colonies are larger then ordinary
blood agar.
 Accessory growth factors are added (factor X and V)
in blood for Haemophilus.

41. 5.Group b
streptococci
PATHOGEN BLOOD AGAR BIOCHEMICAL TEST splTESTS
1. Pneumococcus Small, mucoid,
transparent colony
with alpha
haemolytic. Further
inc. leads to
draughtsman or
carom – coin
appearance of
colonies.
a. Catalase Neg.
b. Oxidase
Neg.
c. Bilesolubility
+ve
a. India ink
b. Quellung’s rxn
2. H. influenzae Blood agar with
streak of
Staph.aureus shows
satellitism.
Satellitism
+ve
Satellitism
3. Corynebacterium
diptheriae
Small, circular,and
glistening with
irregular edges
elek’s gel test Pseudomembrane
detection
4. Mycoplasma Fried egg
appearance
Hemadsorption Serological
examination

42. PATHOGEN BLOOD AGAR BIOCHEMICAL
TEST
splTESTS
5.Staphylococcu
s aureus
Pin point colonies
with beta
haemolysis
Catalase +ve
Coagulase +ve
Serology

43. Fried egg appearance
elek’s gel test

44.  Then antibiotic sensitivity testing is done by -:
Kirby Bauer disc diffusion method.
Stoke method.

45. FUNGAL CULTURE
Inoculated on
 Sabouraud dextrose agar
 BHIA or BHIB
 Plates should be incubated at 37⁰C & 22⁰C.
 LCB is made from culture.

46. ANTIGEN DETECTION
 Detection of antigen in specimen:
Capsular Ag of pneumococci
can be detected by quellung
reaction and latex agg. Test
 H.influenzae and streptococcal Ag
detected by co agglutination test

47. SEROLOGY
Serological test can be used for the
detection of antibody such as
 CFT for Chlamydia sp., mycoplasma
 ELISA, RIA
 Indirect immunofluorescence test for phneumococci
 Immunoperoxidase test etc.
These are used by diagnosis of RTI caused
by viruses and bacteria

48. OTHER TECHNIQUES
Newer tech. such as polymerase chain
Reaction(PCR) can also be used for
diagnosis of RTI

49. TREATMENT
1. Antibacterial agents are
 Ampicillin
 Amoxycillin
 Co-trimoxazole
 Erythromycin
 Penicillin
2. For anaerobes use metronidazole
3. Antituberculous drugs are used for
M.tuberculosis
4. Antifungal agents used for fungal infections
5. Viral infections are self limited, so that no
specific treatment is reqd.

50. THANK
YOU
Have A Nice Day