Bacterial Pneumonia Flashcards
Define pneumonia.
Infection of the Lung Parenchyma
What allows pneumonia to set in?
Local Defense Mechanisms are Lowered or Systemic resistance is lowered:
- Chronic disease, immunologic deficiency, treatment with immunosuppresants, or leukopenia
- Loss of suppression of cough reflex, injury to mucociliary apparatus (smoking), accumulation of secretions (CF), interference of phagocytic action of alveolar macrophages (tobacco, EtOH), Pulmonary Edema
What differentiates:
- Community-Acquired Pneumonia (CAP)
- Hospital-Acquired Pneumonia (HAP)
- Healthcare associated pneumonia (HCAP)
CAP:
• This is what you’re likely to see in everyday patients that come in outpatient
HAP:
• seen 48hrs after hospital admission (wasn’t incubating prior to this)
HCAP:
• Hospitalization for at least 2days in the past 90days OR:
• Has been receiving IV therapy, chemotherapy, or wound care in the last 30 days OR:
• Patient is resident of nursing home long term care facility OR:
• He/she attends hemodyialysis in a clinic or Hospital
Mr. Smith, a 72 year old man who suffers from crohn’s disease, comes in to the clinic with suspected CAP. He remarks that the week prior to developing cough and fever he had suffered from stopped up sinuses. Sputum cultures are taken, but come back negative.
• TYPE OF PNEUMONIA?
• Risk factors?
• Most likely Etiologic Agent?
• Explain the negative sputum cultures.
• Approach to treatment?
*Community Acquired Pneumonia*
Risk Factors:
• Age
• Comorbidities (age)
• Often infection follows URT viral infection (stopped up sinuses)
Most likely Etiologic Agent:
• Streptococcus pneumoniae
Negative Cultures:
• MOST OF THE TIME THE ETIOLOGIC AGENT IS NEVER IDENTIFIED
Differentiated Crackles (rales) and bronchial breath sounds.
Rales:
Scratchy sounds caused by accumulation of fluid/white cells/bacteria in alveolar and interstitial spaces.
Bronchial Breath Sounds:
Dense consolidation of parenchyma results in transmission of large airway noises to the periphery.
You have a patient that has been diagnosed with pneumonia. What are some possible complications that could result from this infection?
- Lung Abscess - from tissue destruction and necrosis
- Empyema - infection spreads to pleural cavity
- Bacteremic dissemination
What are the 3 main causes of Atypical Pneumonia?
• what makes these atypical?
- CXR - disproportionately bad compared to symptoms
- Symptoms - mild and insidious
- CANNOT be isolated on ROUTINE media
3 organisms:
• Mycoplasma pneumoniae
• Chlamydophila pneumoniae
• Lengionella pneumonphila
A lancet shaped gram ________(a) organism is typically responsible for CAP. It produces ________(b) hemolysis on blood agar plates.
• how would you differentiate this organism from staphlococcus aureus?
A lancet shaped gram positive (diplococcus)(a) organism is typically responsible for CAP. It produces alpha (green color) (b) hemolysis on blood agar plates.
• Staph = catalase +, Step. pneumo. = catalase -
Name 3 virulence factors of the pneumonia causing bug that shows the Quellung reaction. Which of these is most important?
• what is the Quellung reaction?
Strep. Pneumo. => Quellung reaction - addition of type-specific anti-sera causes capsule to swell.
3 Virulence Factors:
• Polysaccharide Capsule - without this the SP is not even infectious
- IgA protease - allows for colonization in the URT
- Lipoteichoic acid - activates complement/induces cytokine production
How do you differentiate between Strep viridans and Strep pneumo?
• why is IgA protease an important virulence factor for Strep. pneumo?
Strep. pneumo. => OPTOCHIN SENSITIVE
IgA Protease => enhances ability of organism to colonize the upper respiratory tract.
Would it be possible to get infected with strep. pneumo. more than once? why?
Yes, 85 serotypes of Strep. pneumo means you could get infected several times by the same pathogen.
John (35 y/o) comes in with a severe productive cough, high fever, and pleurtic chest pain. He has sickle cell disease and is positive for antigens against gp160. The infective agent of his disease is suspected to be a gram + lancet shaped diplococcus. answer the following. Blood cultures are negative.
• what are John’s greatest risk factors for disease?
• What type of hemolysis would be seen in this bug?
• green ALPHA-hemolysis would be seen
RISK FACTORS:
• Sickle cell disease
• (auto)splenectomy -while not state most SS patients have autoinfarcted their spleen really bad by this point in their life so no longer have a spleen. This is a problem because the main virulence factor is aPOLYSACCHARIDE CAPSULE
• HIV - gp160 is an HIV antigen
T or F: alcohol/drug intoxication may depress the cough reflex and lead to infection by strep. pneumo.
True
Other Risk Factors:
• Abnormality of respiratory tract - obstruction, infection, injury
• Heart Failure - may also lead to pulmonary congestion and increased risk of infection
What do you expect to see on CXR of strep pneumo patient?
LOBAR consolidation
Jack comes in with CAP that shows lobar consollidation CXR. He is extremely ill and coughing up rusty sputum. CT also indicates the absence of a spleen. Cultures indicate that the bug is catalase negative and optochin sensitive. Susceptibilities are pending.
• Infectious agent?
• Course of Treatment.
Strep. Pneumo.(gram + diplo) => splenectomy (capsule), catalase negative, alpha hemolytic
Course of Treatment:
1. treat empirically on VANCOMYCIN until susceptibilities come back
IF PENICILLIN susceptible then use it (gram + organism). IF NOT
Use CEFTRIAXONE (cephalosporin) if susceptible
***Patient is extremely ill so Fluroquinolones and Azithromycin (macrolide) probably aren’t a good option, but would be okay if he wasn’t so ill***
- Who should get the 23-valent polysaccharide Strep. Pneumo. vaccine?
• how often should these people get re-imunized? - Who should get the 13-valent polysaccharide vaccine?
- Who should get both vaccines?
23 valent:
- Anyone over 65 years old
- anyone 19 to 64 years who is at increased risk for infection (HIV, Diabetes, Splenectomy etc.)
• People should get immunized every 5 years
13 valent:
• Children and infants
BOTH:
• High risk adults
What diseases besides pneumonia does strep. pneumo. cause?
- Meningitis
- Otitis Media
- Sinusitis
A patient is hospitalized for a viral infection (most likely flu) of the respiratory tract and 3 days later develops difficulty breathing and is coughing up copius amount of sputum. CXR shows diffuse infiltration of the right lung with multiple lobe involvment. The suspected agent is gram +.
- what is the suspected agent?
- what risk factors did the patient have for developing this infection?
- is it necessary to test for susceptibilities?
- What complications** is this patient likely to have?
Suspected Agent:
• Staph. Aureus => aside from risk factors diffuse infiltration implies bronchopneumonia which is not caused by other gram +’s like S. pneumo.
Risk Factors:
• S. Aureus is an important cause of POST-FLU pneumonia
• Hospitalization: S. Aureus is an important cause of HAP/HCAP
Susceptibilities:
• NEED THESE b/c S. Aureus is often highly ABX resistant
**Complications:
• Necrotizing Pneumonia
• Lung Abscess
A patient is currently on chemotherapy and develops a pneumonia that grows as gram + cocci in clusters. This bug is both coagulase and catalase positive. Is this patients infectious agent part of the normal flora?
Yes, S. Aureus is normal flora and is both catalase and coagulase positive.
