Discussion on clinical cases of respiratory infections along with MCQs to test theoretical knowledge.

1. MCQs & Case Discussion
Respiratory Infections
Dr. Suprakash Das
MD (Microbiology)

2. Case-1
 A patient comes with complaints of thick purulent nasal
discharge, nasal congestion and facial pain on pressure.
 He has a h/o URTI few days ago. X-ray was performed
and specimens were collected from sinuses which was
used for bacteriological culture.
 One of the suspected organism was sub-cultured. The
characteristics of that organism grown after 24 hrs. is
given below.
 On Biochemical test it is Catalase (-ve), PYR Test
(+ve), Sensitive to Penicillin.
 Identify the probable organism and discuss the case
with provisional diagnosis.

3. Colonies on BA
Gram Stain
Appearance

4. Case-2
 A 50-year-old female patient presented to our otolaryngological ward
complaining of
 right ocular proptosis,
 distending pain,
 blurred vision,
 epiphora,
 bilateral nasal obstruction, and
 rhinorrhea for about 2 mo.
 Four months earlier, the patient was hospitalized in the hematology ward
with a diagnosis of acute myeloid leukemia and treated with
chemotherapy for three cycles.
 Two months earlier, the patient complained of right ocular proptosis,
distending pain, blurred vision, epiphora, bilateral nasal obstruction, and
rhinorrhea after the second cycle of chemotherapy, with a leukocyte
count of 0.4 × 10-9/L and neutrophils at 2.7%.

5. Case-2
 The symptoms did not improve after treatment with an antibiotic
and glucocorticoid;
 Nasal examination showed slight edema of the nasal mucosa,
slight hypertrophy of the bilateral inferior turbinates, and a partial
defect of the mucous membrane of the right middle turbinate.
 Ocular examination showed right ocular proptosis, difficulty of eye
opening, multi-direction activity limitation, chemosis, blindness,
and blackening of the skin of the inner canthus.
 Secretion cultivation of the right eye canthus showed growth of the
organism which is given below.
 What is your provisional diagnosis.
 What is the pathogen involved.

6. LPCB Mount
Colony on BA

7. Case-3
 An 18-year-old female presented to clinic with three days of
painful, swollen tonsils in the setting of recurrent tonsillitis.
 She reported ear pain with swallowing, but no fevers,
dysphagia, or cough.
 She visited urgent care two months prior for the same
complaint and was treated for streptococcal pharyngitis
despite a negative rapid strep test.
 She reported four to five episodes of tonsillitis each year. A
comprehensive sexual history revealed the patient engaged
in penile-oral sex.
 Physical examination was notable for edematous tonsils
with white exudate and tender submental lymphadenopathy.

8. Case-3
 She was afebrile, and there was no erythema of the pharynx.
 The organism isolated from a thraot swab sample shows the
following characteristics shown below.
 The biochemical reactions are as follows-
 Catalase- +ve
 Oxidase- +ve
 TSI- k/a
 Pigment- -ve
 Non-motile
 Indole- (-ve)
 Urea- (-ve)
 Discuss the provisional diagnosis and pathogen involved.

9. Gram Stain
Appearance
Colony on CA

10. MCQs
1. Lemierre’s disease is caused by-
 B. fragilis
 Peptostreptococcus spp
 Clostridium spp.
 None of them
2. Which of the following organism is a major pathogen for HA-Pneumonia
 E. coli
 RSV
 MRSA
 S. pneumoniae
3. Which of the following organism can cause Hypersensitivty Pneumonitis
 Legionella spp.
 Histoplasma capsulatum
 Chlamydophilia psittaci
 None of them

11. MCQs
4. Antigen detection from urine sample to detect a case of pneumonia is for which
organism
 S. pyogens
 MRSA
 HSV
 Legionella pneumophilia
5. Which of the following samples are least useful to detect a case of pneumonia
 Sputum
 Blood
 Bronchoalveolar lavage fluid
 Nasal swab
6. Which of the following is a MDR pathogen responsible for Ventilator associated
pneumonia
 E. coli
 K. pneumoniae
 S. pneumoniae
 Acinetobacter baumannii

12. MCQs
7. Which of the following organism gives such reaction-
 S. pyogens
 S. pneumoniae
 K. pneumoniae
 Cryptococcus neoformans
8. A patient on ventilator develops pneumonia and Gram stain of BAL is given
below. Which of the following antibiotics should be used empirically
 Ampcillin
 Ceftriaxone
 Ciprofloxacin
 Imipenem

14. MCQs
9. Which of the following viruses is associated with Bronchiectasis
 Adenoviruses
 Paramyxoviruses
 RSV
 VZV
10.Which of the following organism is commonly associated with bronchiectasis in
HIV patients
 Klebseilla pneumoniae
 Pneumococcus
 Mycobacterium kansasi
 Mycobacterium intracellularae
11. A patient with severe broncheictasis was admitted and his culture results are shown
below. Which of the following antibiotics best suited his condition.
 Amoxycillin
 Cefepime
 Linezolid
 Piperacillin-Tazobactum

15. Gram
Stain
Culture on NA
Biochemical Tests

16. MCQs
12. Which of the following organism is vaccine preventable
 Heamophilus influenzae type B
 Streptococcus pyogens
 Adeoviruses
 None of them
13.Which of the following is a major pathogen causing Bronchiolitis
 RSV
 Adenovirus
 Measeals virus
 None of them
14. Which of the following organism is vaccine preventable
 Influenza virus type-B
 EBV
 Streptococcus pneumoniae
 Klebseilla pneumoniae

17. MCQs
15. Identify the culture media.
 CN agar
 HE agar
 TCBS agar
 None of them
16.Isoniazide resistance in M. tuberculosis is detected by
 Solid media culture
 Gene Xpert
 LPA
 None of them
17.BCG vaccine is prepared from which strain
 M. africanum
 M. tuberculosis
 M. bovis
 M. kansasi

18. Case-4
 A boy aged 12 years presented to the tuberculosis clinic (TB) with a several
year history of a chronically productive cough with associated shortness of
breath and wheeze.
 He also reported of lethargy, night sweats and weight loss. He had been
screened for TB, with a negative Mantoux test, 5 years previously.
 On initial examination at the TB clinic, his chest was clear on auscultation
and he had several small submandibular lymph nodes. His height and
weight were on the 9th centile for his age.
 Repeat TB investigations, including Mantoux, T-spot and sputum AFB,
were negative.
 Examination at this point revealed finger clubbing.
 High-resolution CT chest showed widespread bronchiectasis with evidence
of mucus plugging.
 Sweat test revealed a high chloride level of 81 mmol/L.
 The boy develops a lung infection, the culture result of the organism is
given below.
 What is your provisional diagnosis?

19. Gram
Stain
Culture on NA
Biochemical Tests

20. Case-5
 A 39-year-old apparently healthy woman complained of fever
and productive cough, in March, 2017.
 She didn’t have any significant medical history.
 Three days after onset (clinical day 3), she was admitted to a
local general hospital, owing to progressive fever, malaise, and
anorexia. On admission her vitals were stable.
 Her white blood cell count was 5600/μL, with a shift to the left
(81.2% neutrophils).
 the patient’s chest X-ray and chest computed tomography (CT)
images revealed subsegmental consolidation in her right lower
lobes,

21. Case-5
 bronchoalveolar lavage (BAL) and a transbronchial biopsy
of the right lower lobe were performed.
 These examinations revealed nonspecific inflammation with
neutrophil infiltration, but no pathogen was identified on
pathological or microbiological examination (Gram stain).
 The BAL fluid was cultured on special selective media and
the culture results are given below
 What is the provisional diagnosis?
 What is the probable pathogen?
 What is the culture media used?
 What is the choice of drug?

22. Colony Characteristics
Biochemical Tests-
Glucose Fermentation- +ve
Urea Hydrolysis- (-ve)

23. Case-6
 A 58-year-old white Caucasian British lady, came to the
emergency department with a 2 day history of
 high fever (38.6°C) shortness of breath, productive cough
and diarrhoea 3 days after she had arrived from New Jersey.
 In the emergency department, her respiratory rate was 21/
min, blood pressure 88/57 mmHg, and heart rate 116/ min
and regular and Arterial oxygen saturation was 77% on
room air and increased to 90% on 100% oxygen via a face
mask.
 Rales were present in one third of the lung fields bilaterally
and percussion revealed dullness at the base of the right
lung, with poor air entry in the right lower base.

24. Case-6
 A chest radiograph showed extensive consolidation present
throughout the right lung and there was also a little patchy
consolidation in the left mid and lower zones.
 The patient develops septic shock, ARDS & DIC.
 On the 7th admission day, antigen of a suspected pathogen
was detected from urine and also that pathogen was isolated
from sputum. The culture results are given below.
 The patient responded to Ceftriaxone therapy.
 What is your provisional diagnosis?
 Causative organism?
 Selective media and other tests to diagnose that organism?
 Drug of choice ?

25. Biochemical Tests-
Oxidase- (-ve)
Urease- (-ve)
Gelatin hydrolysis-(+ve)
Motile
Gram Stain

27. ANSWERS
CASE-1
 Streptococcus pneumoniae
 Bacterial sinusitis
Case-2
 Invasive fungal sinusitis
 Cunninghamella bertholletiae- The genus Cunninghamella is characterised by
white to grey, rapidly growing colonies, producing erect, straight, branching
sporangiophores.
 These sporangiophores end in globose or pyriform-shaped vesicles from which
several one-celled, globose to ovoid, echinulate or smooth-walled sporangiola
develop on swollen denticles. Chlamydospores and zygospores may also be
present.
 Cunninghamella species are mainly soil fungi of the Mediterranean and
subtropical zones; they are only rarely isolated in temperate regions.
 The genus now contains seven species with C. bertholletiae the only known
species to cause disease in humans and animals, often in association with trauma
and immunosuppression.

28. ANSWERS
Case-3
 Gonococcal Pharyngitis
 Nisseria gonorrhoae
Case-4
 A case of Cystic Fibrosis and associated lung infection
 Pathogen- P. aeruginosa
Case-5
 Atypical pneumonia
 Mycoplasma pneumoniae
 PPLO agar
 Doxycyclin & Macrolides (Azithromycin)
Case-6
 Legionnaires' disease- type of pneumonia
 Legionella pneumophila
 BYCE agar
 Macrolides & Fluroqinolones

29. MCQs-Answers
1. None of them (Fusobacterium necrophosum)
2. MRSA
3. C. psittaci
4. L. pneumophilia
5. Nasal swab
6. A. baumannii
7. S. pneumoniae
8. Imipenem
9. Adenoviruses
10. M. intracellularae
11. Piperacillin-Tazobactum
12. Haemophilus inflenzae type-B
13. RSV
14. S. pneumoniae
15. None of them (L-J Media)
16. LPA
17. M. bovis.