Respiratory Tract Infections

Question 1

Pathogen frequencies in Adult EPIC study of pneumonia

Answer 1

Pathogens in ~1/3 of patients; 22% with virus; 14% with bacteria (with or without virus): Strep pneumo>Mycoplasma>Staph aureus

Question 2

Prevalence of and risk factors for MRSA in CAP

Answer 2

<5% in inpatients with CAP; RF prior MRSA infection/colonization, recurrent skin infections, severe PNA

Question 3

Characteristics of Mycoplasma CAP

Answer 3

<40 years old, live/work in crowded areas

Question 4

Characteristics of Legionella CAP

Answer 4

Outbreaks related to water, males, influenza-like prodrome

Question 5

Characteristics of Chylamydophila CAP

Answer 5

Gradual nonspecific symptoms starting with URI symptoms

Question 6

Pneumococcal vaccination recommendations for patients >65 years old (with no other indications)

Answer 6

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

Question 7

Significance of follow-up imaging for CAP

Answer 7

CAP resolves slowly on CXR; thus if CXR findings resolve rapidly, CAP becomes less likely

Question 8

Predictive value of nasal PCR for MRSA on likelihood of MRSA pneumonia

Answer 8

High negative predictive value in areas of low MRSA pneumonia incidence

Question 9

Procalcitonin cutoff for ruling-out pneumonia

Answer 9

<0.25 makes pneumonia unlikely

Question 10

CURB-65 calculation and hospitalization cutoff

Answer 10

1 point each for: Confusion, Uremia (BUN>19), RR>30, BP<90/60, >65 years old. Score of 2 or greater: consider hospitalization

Question 11

CAP-START study design

Answer 11

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%).

Question 12

CAP-START main findings

Answer 12

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.

Question 13

Swiss CAP study design

Answer 13

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).

Question 14

SWISS CAP study findings

Answer 14

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.

Question 15

Criteria for discontinuation of CAP therapy at day 5

Answer 15

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

Question 16

CAP d/c at day 5 study design

Answer 16

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.

Question 17

CAP d/c therapy at day 5 study results

Answer 17

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.

Question 18

Procalcitonin characteristics

Answer 18

(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.

Question 19

Procalcitonin categories for continuation of antibiotics in RTI

Answer 19

<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

Question 20

Characteristics of seasons in which H3N2 predominates vs H1N1 or B

Answer 20

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.

Question 21

Infection control precautions for hospitalized patients with influenza

Answer 21

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

Question 22

Greatest cause of death of children worldwide

Answer 22

Pneumonia is the single greatest cause of death in children worldwide

Question 23

Etiologies of CAP in children

Answer 23

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

Question 24

Risk factors for severe pneumonia in children

Answer 24

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.

Question 25

Criteria for hospital admission for pediatric CAP

Answer 25

any child or infant with respiratory distress (Table 3) should be admitted to the hospital for management

admission is indicated in a previously healthy child with CAP and an oxygen saturation in room air (at sea level) of ,90%, although some would hospitalize chil- dren who have oxygen saturations as high as 93%

Question 26

Simple vs Complicated CAP

Answer 26

‘‘simple pneumonia’’ as either broncho- pneumonia (primary involvement of airways and surrounding interstitium), or lobar pneumonia involving a single lobe.

‘‘Complicated pneumonia’’ is defined as a pulmonary paren- chymal infection complicated by parapneumonic effusions, multilobar disease, abscesses or cavities, necrotizing pneumonia, empyema, pneumothorax or bronchopleural fistula; or pneu- monia that is a complication of bacteremic disease that includes other sites of infection.

Question 27

Empiric antimicrobial therapy for preschool-aged c;hindrance with CAP

Answer 27

Antimicrobial therapy is not routinely required for preschool-aged children with CAP, because viral pathogens are responsible for the great majority of clinical disease. (strong recommendation; high-quality evidence)

Most preschool-aged children with pediatric CAP, when tested with sensitive PCR techniques for respiratory viruses (such as rhinovirus, RSV, human metapneumovirus, para- influenza viruses, influenza A and B viruses, adenovirus, coronavirus, and human bocavirus), and bacteria (including S. pneumoniae, H. influenzae, and M. pneumoniae) are found to be positive for respiratory viruses more often than for bacteria

Question 28

Empiric therapy for outpatient pediatric CAP in otherwise healthy children and infants

Answer 28

Amoxicillin should be used as first-line therapy for previously healthy, appropriately immunized infants and preschool-aged children with mild to moderate CAP suspected to be of bacterial origin.

Amoxicillin should be used as first-line therapy for previously healthy, appropriately immunized school-aged children and adolescents with mild to moderate CAP for S. pneumoniae, the most prominent invasive bacterial pathogen. Atypical bacterial pathogens (eg, M. pneumoniae) and less common lower respiratory tract bacterial pathogens, as discussed in the Evidence Summary, should also be considered in management decisions. (strong recommendation; moderate- quality evidence)

Question 29

Empiric therapy for CAP for healthy children

Answer 29

Ampicillin or penicillin G should be administered to the fully immunized infant or school-aged child admitted to a hospital ward with CAP when local epidemiologic data document lack of substantial high-level penicillin-resistance for invasive S. pneumoniae.

Empiric therapy with a third-generation parenteral cephalosporin (ceftriaxone or cefotaxime) should be prescribed for hospitalized infants and children who are not fully immunized, in regions where local epidemiology of invasive pneumococcal strains documents high-level penicillin resistance, or for infants and children with life- threatening infection, including empyema

Question 30

Treatment duration for pediatric CAP

Answer 30

Treatment courses of 10 days have been best studied, although shorter courses may be just as effective, particularly for more mild disease managed on an outpatient basis. (strong recommendation; moderate-quality evidence)

Question 31

Dosing of amoxicillin in pediatric CAP

Answer 31

To achieve the appropriate amoxicillin exposure in lung infected by relatively resistant pneumococci (MICs of 2.0 lg/mL), a high total daily dose (90 mg/kg/day) in 3 equally divided portions is predicted to achieve a clinical and microbiologic cure in about 90% of children treated,

Question 32

Penicillin breakpoints for Strep pneumo

Answer 32

IV PCN: S: <=2, I=4, R=>8

PO PCN: S: <=0.06 I=0.12-1 R=>2