Respiratory Tract Infections Flashcards
Pathogen frequencies in Adult EPIC study of pneumonia
Pathogens in ~1/3 of patients; 22% with virus; 14% with bacteria (with or without virus): Strep pneumo>Mycoplasma>Staph aureus
Prevalence of and risk factors for MRSA in CAP
<5% in inpatients with CAP; RF prior MRSA infection/colonization, recurrent skin infections, severe PNA
Characteristics of Mycoplasma CAP
<40 years old, live/work in crowded areas
Characteristics of Legionella CAP
Outbreaks related to water, males, influenza-like prodrome
Characteristics of Chylamydophila CAP
Gradual nonspecific symptoms starting with URI symptoms
Pneumococcal vaccination recommendations for patients >65 years old (with no other indications)
Previously unvaccinated: PCV13 first, then PPSV23 at least 1 year later. Previous PPSV23: PCV13 at least 1 year after. PPSV23 doses may be readministered, at least 5 years apart
Significance of follow-up imaging for CAP
CAP resolves slowly on CXR; thus if CXR findings resolve rapidly, CAP becomes less likely
Predictive value of nasal PCR for MRSA on likelihood of MRSA pneumonia
High negative predictive value in areas of low MRSA pneumonia incidence
Procalcitonin cutoff for ruling-out pneumonia
<0.25 makes pneumonia unlikely
CURB-65 calculation and hospitalization cutoff
1 point each for: Confusion, Uremia (BUN>19), RR>30, BP<90/60, >65 years old. Score of 2 or greater: consider hospitalization
CAP-START study design
cluster randomized, crossover, noninferiority trial of inpatient non-ICU CAP was conducted in the Netherlands (CAP-START study; N Engl J Med 2015;372:14). The study aimed to compare 90-day mortality in three treatment groups: β-lactam monotherapy, fluoroquinolone monotherapy, and β-lactam plus macrolide. The noninferiority margin was set at 3%. median age of the patient population was 70, and the median CURB-65 score was 1 (interquartile range 1–2). three most commonly isolated pathogens were S. pneumoniae (15.9% of patients), H. influenzae (6.8%), and atypical pathogens (2.1%).
CAP-START main findings
Found β-lactam monotherapy was noninferior to combination therapy for
non-severe CAP. Of note, 25% of patients deviated from study protocol and were placed
on combination therapy, which may have limited the ability to detect differences in treat-
ment effects.
Swiss CAP study design
assessed clinical stability at day 7 in immunocompetent adults with moderately severe CAP receiving β-lactam monotherapy (intravenous cefuroxime or intravenous amoxicillin/clavulanate) versus β-lactam–macrolide combination therapy (intravenous or oral clarithromycin) (JAMA Intern Med 2014;174:1894- 901).
SWISS CAP study findings
At day 7 of therapy, 41.2% and 33.6% of patients in the monotherapy and combination
arms had not reached clinical stability (p=0.07). The upper limit of the 90% CI was 13%,
which was greater than the predefined noninferiority margin of 8%; thus, noninferiority
of monotherapy was not found.
In a subgroup analysis that excluded patients infected with atypical bacteria, the proportion not attaining clinical stability at 7 days in the monotherapy arm was still greater (7.6% vs. 5.8%) but not statistically significant.
Criteria for discontinuation of CAP therapy at day 5
To be eligible for treatment discontinuation at day 5, patients must not have had a temperature greater than 100°F (37.8°C) in the past 48–72 hours AND must have met at least three of the following four criteria: (a) Heart rate of 100 beats/minute or less (b) Respiratory rate of 24 breaths/minute or less (c) Systolic blood pressure of 90 mm Hg or greater (d) Sao2 of 90% or greater or Pao2 of 60 mm Hg or greater on room air
CAP d/c at day 5 study design
an RCT evaluated these criteria in making decisions to discontinue antimicro- bial therapy at 5 days in hospitalized patients with CAP (JAMA Intern Med 2016;176:1257-65). intervention group required antibiotic therapy for at least 5 days, and antibi- otics were discontinued once the patient was afebrile (temperature 100°F [37.8°C] or less) for 48 hours and had no more than one of the aforementioned signs of clinical instability. intention-to-treat population included 312 patients with a mean age of about 65 years, 63% male, and a mean pneumonia severity index score of 83. Fluoroquinolones were used in 80% of patients.
CAP d/c therapy at day 5 study results
median duration of antibiotic therapy in the control and intervention groups was 10 and 5 days, respectively (p<0.001) Clinical success at day 10 occurred in 71 of 150 (48.6%) and 90 of 162 (56.3%) in the control and intervention groups, respectively (intention-to- treat analysis, p=0.18). Readmission at 30 days occurred in 6.6% and 1.4% of the control and intervention group patients, respectively (p=0.02). Most patients received fluoroquinolones, and though not adequately powered, an analysis of outcomes by antibiotic class revealed no differences.
Procalcitonin characteristics
(1) Procalcitonin is not affected by immunosuppression and rises within 6 hours of bac- terial infection. (2) Half-life of around 24 hours (procalcitonin should decrease by 50% once bacterial infection controlled by antibiotics/host immune system 3) generally not suggested to withhold antibiotic therapy solely on the basis of a single negative procalcitonin value. Procalcitonin may take 6 hours to increase after the onset of infection; thus, initial negative values should be repeated after 6–24 hours if initially negative.
Procalcitonin categories for continuation of antibiotics in RTI
<0.1 or drop by 90%: cessation strongly encouraged
0.1-0.25 or drop by 80-90%: cessation encouraged
0.25-0.5: cessation discouraged
>0.5: cessation strongly discouraged
Characteristics of seasons in which H3N2 predominates vs H1N1 or B
H3N2 predominated in the 2016–2017 season; there is more severe illness, particularly in young individuals and older adults, during seasons in which H3N2 is predominant as opposed to H1N1 or B virus.
Infection control precautions for hospitalized patients with influenza
droplet precautions for hospitalized patients with sus- pected or confirmed influenza; further, these precautions are recommended for 7 days after illness onset or until 24 hours after the resolution of fever and respiratory symptoms, whichever is longer
Greatest cause of death of children worldwide
Pneumonia is the single greatest cause of death in children worldwide
Etiologies of CAP in children
In some studies, viral etiologies of CAP have been docu- mented in up to 80% of children younger than 2 years; in contrast, investigations of older children, 10–16 years, who had both clinical and radiographic evidence of pneumonia, documented a much lower percentage of viral pathogen
Of viral pathogens, RSV is consistently the most frequently detected, representing up to 40% of identified pathogens in those younger than 2 years, but rarely identified in older children with CAP.
‘‘atypical pneumonia’’ have been identified in 3%–23% of children studied, with M. pneumoniae most often identified in older children and C. pneumoniae in infants
Nontypeable H. influenzae is not usually considered a pathogen in pediatric pneumonia except in chronic lung disease or if chronic obstruction develops
Risk factors for severe pneumonia in children
The incidence of pneu- monia and risk of severe pneumonia are greater in infants and young children.
infants and young children tend to have more severe pneumonia with a greater need for hospitalization and a higher risk of respiratory failure.
