1. Atypical Bacterial Pneumonia
Dina Abouelkheir
Lecturer of chest medicine-MUH
2015

2. Why it is called “Atypical”???
The atypical organisms cannot be cultured on standard media, nor can they be seen on Gram’s stain.
Have atypical presentation
Often cause extrapulmonary manifestations
Intrinsically resistant to all β-lactam agents as most of the atypical pathogens do not have a bacterial cell wall

3. Causes of Atypical pneumonia
Bacteria
Mycoplasma (M. pneumoniae)
Chlamydophila (C. psittaci, C. pneumoniae)
Legionella
F. tularensis
Y. pestis
B. anthracis
Rickettsia
C. burnetii (Q fever)
Respiratory tract viruses
Influenza, adenovirus, respiratory syncytial virus, parainfluenza virus
Other viral agents
Varicella-zoster, measles, Epstein-Barr virus, CMV, metapneumovirus, Hantavirus
Fungi
Histoplasma, Blastomyces, Coccidioides, Pneumocystis

4. Epidemiology Legionella
Atypical CAPs represent approximately 15% of all CAPs.
Legionella
Sources of infection include domestic hot and cold water systems, wet cooling systems, natural spas, humidifiers, ultrasonic mist machines, respiratory therapy equipment.
- The attack rate is higher in:
the elderly
tobacco smokers, alcoholism
those with chronic lung disease
diabetes mellitus
ICH

5. Mycoplasma (M. pneumoniae)
The organism is spread by droplet aerosol
Chlamydophila (C. psittaci, C. pneumoniae)
C. psittaci may be hosted by many avian species
Psittacine infection is an occupational hazard of veterinarians, pet-shop workers, zoo staff and poultry workers.

6. Clinical Presentation
Fever, chills, pleuritic chest pain
Cough: non-productive or productive of mucoid sputum only.
Dyspnea
Physical findings of consolidation
Pleural friction rub

7. Typical and Atypical Presentation of CAP:

8. Extrapulmonary Manifistations
Bradycardia
Hyponatremia
Diarrhea: 20%
Mental confusion
Glomerulonephritis
Legionella
Bullous myringitis (painful haemorrhagic blisters on the ear-drum and external auditory canal)
Splenomegaly
Lymphadenopathy
Maculopapular skin rash
Mycoplasma

9. Hepatitis
Palpable splenomegaly
Endocarditis
Stevens–Johnson syndrome
Erythema nodosum
Chlamydia

10. Bullous myringitis

11. Steven Johnson Syndrome

12. Erythema nodosum

13. Radiology

14. Patchy reticular or reticulonodular opacities.
Subsegmental and sometimes segmental atelectasis.
 Hilar adenopathy
 Pleural effusion

15. Severe Legionella pneumonia
Severe Legionella pneumonia. Chest radiograph shows dense consolidation in both lower lobes.

16. Legionella pneumonia

17. Mycoplasma Pneumonia

18. Chlamydia pneumonia. CXR shows multifocal, patchy consolidation in the right upper, middle, and lower lobes

19. Investigations Sputum microscopy:
The absence of large numbers of organisms in an adequate sputum sample raises the possibility of Legionella pneumophila, Mycoplasma pneumoniae, Coxiella burnetii or a viral pneumonia.

20. Urine Antigen detection Legionella spp.
Sputum culture
Legionella spp. → selective charcoal yeast extract medium. Result is relatively slow, taking about 3 days.
Urine Antigen detection
Legionella spp.

21. Standard acute and convalescent serological testing
Complement-fixing antibody levels in the blood
Enzyme-linked immunosorbent assay (ELISA)
Immunofluorescent tests
PCR

22. Haematological and biochemical measurements
White cell count: normal or increased (Legionella )
ESR : raised.
Mild abnormalities of liver and renal function including proteinuria and microscopic haematuria
Raised LDH and creatine kinase (Legionella )
Hyponatraemia (Legionella )

23. IgM cold agglutinins: Mycoplasma
This test is usually done by combining the patient’s serum with type O red cells in the laboratory. If clumping is noted, the serum is serially diluted and the test repeated, the titre reported being the highest dilution at which clumping occurs at 4°C

24. complications Chlamydia Mycoplasma Legionella rare √√
respiratory failure √
Empyema, cavitation
Cardiac: pericarditis, myocarditis and endocarditis
Neurological :confusion, memory impairment, cerebellar ataxia, GBS
Pancreatitis
Cellulitis
Renal failure
Autoimmune hemolytic anaemia
SIADH
Steven Johnson Syndrome

25. to treat Atypical Pneumonia????
Treatment
Can we use
B-LACTAM ANTIBIOTICS
to treat Atypical Pneumonia????

26. Antibiotics: Add on therapy Macrolides Doxycycline Quinolone
Rifampicin (legionella, chlamydia)
Steroids (mycoplasma)

27. Doses 500 mg/ 6-hours Erythromycin 500 mg/24 hours Azithromycin
200 mg for the first dose
Followed by 100 mg / 12-hours
Doxycycline
400mg/8 hours IV OR
750 mg orally /12 hours
Ciprofloxacin
750 mg/24 hours
Levofloxacin
400 mg/24 hours
Moxifloxacin
600 mg /12 hours
Rifampicin

28. Duration
It is recommended that treatment is continued for 2–3 weeks for fear that shorter periods may result in delayed resolution or relapse, particularly in those who are immunosuppressed or who have extensive disease.

29. Prevention of Legionella pneumonia
 Identification of the sources where epidemics or case clustering have occurred.
Hot water supplies are usually decontaminated by hyperchlorination, or by superheating water supplies to 70–80°C, and by the removal of rubber washers from shower fittings.