01Approach to the Critical Patient/attcp56

Immediate priorities

›Airway and oxygenation threats

›Respiratory failure requiring immediate intervention

›SpO2 <90% on room air or FiO2 >0.35 to maintain saturation

›PaO2/FiO2 ratio <250 mmHg (IDSA/ATS minor criterion)

›Respiratory rate >30 breaths/min with accessory muscle use

›Escalation pathway

›HFNC for hypoxemic respiratory failure without hypercapnia

›NIV if COPD or early hypercapnia without vomiting risk

›Intubation for impending respiratory failure or airway compromise

›Hemodynamic stabilization

›Septic shock criteria

›SBP <90 mmHg or MAP <65 mmHg despite 30 mL/kg crystalloid

›Lactate >=4 mmol/L indicating tissue hypoperfusion

›Vasopressor requirement after adequate fluid resuscitation

›Immediate actions

›Two large-bore IV lines and continuous cardiac monitoring

›Arterial line for hemodynamic monitoring in shock

›Norepinephrine 0.01-0.5 mcg/kg/min for refractory hypotension

›Antibiotic timing

›Time-to-antibiotic targets

›Within 1 hour for septic shock (Class I recommendation, IDSA/ATS 2016)

›Within 3 hours for severe pneumonia without shock

›Blood cultures x2 before antibiotics if feasible without delay

›Empiric broadening criteria

›Prior hospitalization >=2 days in past 90 days

›Nursing home or LTCF residence

›Prior IV antibiotics within 90 days (strongest MDR predictor)

02History/hx68

Presenting symptoms

›Core respiratory symptoms

›Cough character and productivity

›Purulent sputum (yellow or green)

›Foul-smelling sputum (aspiration-related anaerobic infection)

›Hemoptysis (cavitary disease, MRSA, malignancy)

›Dyspnea onset and trajectory

›Acute vs. subacute progression

›Exertional limitation compared to baseline

›Fever or chills

›May be absent in elderly or immunocompromised

›Rigors suggesting bacteremia

Healthcare exposure history

›HCAP-defining exposures

›Recent hospitalization

›>=2 days in prior 90 days (strongest MDR risk factor, 4 points Shorr score)

›Nursing home or LTCF residence

›3 points on Shorr MDR risk score

›Chronic hemodialysis

›2 points on Shorr MDR risk score

›Vascular access site as concurrent infection source

›Home wound care or home infusion therapy

›Prior IV antibiotic use within 90 days

›Strongest independent predictor of MDR pathogen

Risk factors for MDR pathogens

›Pathogen-specific risk factors

›MRSA risk factors

›Prior MRSA colonization or infection

03Physical Exam/exam59

Vital signs and general

›Vital sign assessment

›Temperature

›May be absent in elderly or immunosuppressed (blunted response)

›Hypothermia <36 C suggests severe sepsis

›Respiratory rate

›>=30 breaths/min: IDSA/ATS minor criterion for severe pneumonia

›Strongest vital sign predictor of ICU need

›Blood pressure and MAP

›SBP <90 or MAP <65 mmHg: major criterion for ICU admission

›SpO2 on room air

›<90% is IDSA/ATS minor criterion

›Heart rate

›Tachycardia >120 may reflect sepsis, PE, or new arrhythmia

Pulmonary examination

›Auscultation findings

›Crackles or rales

›Localized: consolidation

›Bilateral: multilobar pneumonia or superimposed CHF

›Bronchial breath sounds and egophony

›Lobar consolidation pattern

›Decreased breath sounds

›Pleural effusion or empyema below

›Percussion

›Dullness to percussion

›Parapneumonic effusion

›Empyema

›Work of breathing

04Differential Diagnosis/ddx44

Life-threatening diagnoses

›Must-not-miss diagnoses

›Pulmonary embolism

›ICD-10: I26.99

›Particularly in immobilized or post-hospitalization patients

›Differentiate: pleuritic pain, absence of productive cough, D-dimer, CTPA

›Necrotizing pneumonia

›ICD-10: J18.9

›MRSA, Klebsiella pneumoniae, Pseudomonas aeruginosa

›Cavitary lesion on imaging, rapid clinical deterioration

›Empyema

›ICD-10: J86.9

›Loculated pleural effusion on imaging, failure to improve

›Requires drainage; do not treat with antibiotics alone

›Lung abscess

›ICD-10: J85.1

›Air-fluid level on CXR or CT, foul-smelling sputum

›Active pulmonary tuberculosis

›ICD-10: A15.0

›Upper lobe cavitary disease, weight loss, night sweats, high-risk exposure

›Sepsis from non-pulmonary source

›Incidental atelectasis may mimic infiltrate

›Search for urinary, abdominal, or vascular access source

Common mimics

›Diagnostic mimics

›Acute exacerbation of COPD

›ICD-10: J44.1

›May coexist with pneumonia; CXR infiltrate clarifies

05Laboratory Tests/lt72

Essential bloodwork

›Complete blood count

›Leukocytosis >15 x10^9/L

›Typical in bacterial pneumonia

›Leukopenia <4 x10^9/L

›Suggests overwhelming sepsis or immunosuppression

›IDSA/ATS minor criterion

›Thrombocytopenia

›Disseminated intravascular coagulation or sepsis

›Basic metabolic panel

›BUN elevation

›CURB-65 criterion: >=7.1 mmol/L (1 point)

›Dehydration and prerenal azotemia common

›Creatinine

›Renal dosing adjustments for antibiotics

›Acute kidney injury indicates severe sepsis (SOFA criterion)

›Sodium

›Hyponatremia: IDSA/ATS minor criterion, Legionella association

›Glucose

›Hyperglycemia in diabetic; stress hyperglycemia in non-diabetic

Infection and inflammation markers

›Lactate

›Lactate >=4 mmol/L

›Septic shock criterion even with adequate blood pressure

›Lactate 2-4 mmol/L

›Cryptic shock; warrants ICU-level monitoring

›Serial lactate clearance

›Target >10% reduction at 2 hours

›C-reactive protein and procalcitonin

›Procalcitonin

›Not validated for antibiotic initiation decisions in HCAP

›Serial measurements guide antibiotic duration (Class IIb recommendation)

›PCT <0.25 mcg/L supports discontinuation in improving patient

›CRP

›Acute phase reactant, nonspecific but follows treatment response

Microbiological investigations

›Blood cultures

›Two sets from separate sites before antibiotics

›Sensitivity 20-35% in pneumonia, low but high specificity

›Critical for antibiotic de-escalation when positive

›Do not delay antibiotic administration >45 minutes to obtain cultures

›Sputum culture

›Gram stain and culture from expectorated sputum

›Adequate specimen: >25 PMN and <10 squamous cells per low-power field

›Semi-quantitative culture: >=10^5 CFU/mL significant

›Induced sputum for Mycobacterium tuberculosis if suspected

›Urinary antigen tests

›Legionella urinary antigen

›Detects serogroup 1 only (80% of Legionella pneumophila)

›Sensitivity 70-80%, specificity 99%

›Order when severe pneumonia or LTCF exposure

›Streptococcus pneumoniae urinary antigen

›Sensitivity 60-80%, specificity 97%

›Rapid result supports early de-escalation

Advanced diagnostics

›Molecular diagnostic panels

›BioFire FilmArray Pneumonia Panel

›Detects 33 respiratory pathogens including resistance genes

›Result within 1-2 hours from respiratory specimen

›Identifies mecA (MRSA), KPC, OXA-48, VIM, IMP resistance genes

›Increasingly used in HAP/VAP settings (IDSA/ASM 2024 guidelines)

›Arterial blood gas

›PaO2/FiO2 ratio calculation

›<300 mmHg: lung injury

›<250 mmHg: IDSA/ATS minor criterion for severe pneumonia

›<200 mmHg: ARDS criteria

›pH and PaCO2

›Respiratory alkalosis: early compensation

›Respiratory acidosis: ventilatory failure

›Additional tests

›Troponin

›Rule out type 2 MI in hemodynamically unstable patient

›D-dimer

›Low-probability PE rule-out if indicated

›LDH and albumin

›Prognostic markers; hypoalbuminemia predicts poor outcome

06Diagnostic Tests/dt104

Scoring Systems

›CURB-65 score

›Confusion (new): 1 point

›MMSE <=8 or disorientation in time, place, or person

›Urea (BUN) >=7.1 mmol/L: 1 point

›Respiratory rate >=30 breaths/min: 1 point

›Blood pressure SBP <90 or DBP <=60 mmHg: 1 point

›Age >=65 years: 1 point

›Score interpretation

›0-1: low risk, outpatient treatment appropriate

›2: intermediate risk, consider inpatient or short-stay

›>=3: high risk, hospitalization indicated; >=4 ICU consideration

›Validated AUC 0.65-0.66 for 30-day mortality prediction in HCAP

›Pneumonia Severity Index (PSI/PORT)

›20-variable risk stratification tool

›Demographics, comorbidities, exam findings, labs, imaging

›Risk class interpretation

›Class I-II: very low risk (<1% mortality)

›Class III: low risk (2.8% mortality); consider outpatient

›Class IV: moderate risk (8.5% mortality); inpatient recommended

›Class V: high risk (29.2% mortality); hospitalization required

›Best discriminatory ability for HCAP mortality (AUC 0.68-0.72)

›IDSA/ATS Minor Criteria for severe pneumonia

›Minor criteria (>=3 required for ICU admission)

›RR >=30 breaths/min

›PaO2/FiO2 ratio <=250 mmHg

›Multilobar infiltrates

›Confusion or disorientation

›BUN >=7.1 mmol/L

›Leukopenia <4 x10^9/L

›Thrombocytopenia <100 x10^9/L

›Hypothermia <36 C

›Hypotension requiring aggressive fluid resuscitation

›Major criteria (either = ICU admission)

›Mechanical ventilation

›Septic shock requiring vasopressors

›Shorr MDR Pathogen Risk Score

›Scoring components

›Recent hospitalization >=2 days/90 days: 4 points

›LTCF/nursing home residence: 3 points

›Chronic hemodialysis: 2 points

›ICU admission at presentation: 1 point

›Score >=6: approximately 75% prevalence of MDR pathogens

›Used to guide empiric antibiotic broadening decisions

›SOFA and qSOFA scores

›SOFA score

›>=4 has 100% specificity for 30-day mortality in HCAP

›Requires PaO2/FiO2, platelets, bilirubin, creatinine, MAP, GCS

›qSOFA (bedside screen)

›Altered mentation: 1 point

›SBP <=100 mmHg: 1 point

›RR >=22 breaths/min: 1 point

›>=2 points: screen positive for sepsis

MRI

›MRI chest

›Role in HCAP

›Not first-line; rarely used in acute pneumonia

›Consider for superior soft tissue detail in complex mediastinal disease

›Radiation-free alternative in pregnant patients when CT is equivocal

›Findings

›Consolidation: T1 isointense, T2 hyperintense

›Parapneumonic effusion vs. empyema: DWI restricted diffusion in empyema

CT

›CT chest (non-contrast)

›Indications

›Non-resolving pneumonia at 6-8 weeks (exclude underlying malignancy)

›Suspected lung abscess (air-fluid level) or cavitary lesion

›Suspected empyema or complex parapneumonic effusion

›Equivocal CXR with high clinical suspicion

›Immunocompromised host with atypical presentation

›Key findings

›Consolidation pattern: lobar vs. bronchopneumonic vs. interstitial

›Cavitation: MRSA, Klebsiella, anaerobes, TB

›Air bronchograms within consolidation (patent airways, not empyema)

›Pleural enhancement with split pleura sign (empyema vs. effusion)

›Ground-glass opacities: early pneumonia, viral, PCP, organizing pneumonia

›Multilobar disease: severity marker, IDSA/ATS minor criterion

›CT angiography (CTPA) if PE concurrent concern

›Post-hospitalization patients at elevated DVT/PE risk

›Plain chest radiograph (CXR)

›First-line imaging in all suspected HCAP

›PA and lateral views preferred; portable AP if unstable

›Confirms pulmonary infiltrate (new opacity not explained by other cause)

›Identifies complications: effusion, cavitation, multilobar disease

›Limitations

›Sensitivity 58-77% for pneumonia vs. CT

›Portable AP may underestimate effusion and consolidation

›Radiographic improvement lags clinical recovery by 4-12 weeks

Ultrasound

›Point-of-care lung ultrasound (POCUS)

›Consolidation detection

›Hepatization pattern (tissue-like echotexture replacing air)

›Dynamic air bronchograms within consolidation (patent bronchi)

›Sensitivity comparable to CT for consolidation (>90% in expert hands)

›Pleural effusion assessment

›Anechoic: simple transudative effusion

›Complex/septated: exudate, empyema, hemothorax

›Guides thoracentesis positioning and volume estimation

›B-lines (comet tail artifacts)

›>=3 B-lines per interspace: alveolar-interstitial syndrome

›Bilateral diffuse B-lines: pulmonary edema vs. ARDS vs. bilateral pneumonia

›Advantages over CXR

›Real-time bedside use in unstable patients

›No radiation

›Dynamic reassessment during treatment

›Diaphragm ultrasound

›Excursion <1.5 cm in critically ill suggests diaphragmatic dysfunction

›Predicts weaning failure in intubated patients

07Disposition/dispo38

Admission criteria

›Inpatient admission indications

›PSI/PORT Class IV or V

›Moderate to high mortality risk

›CURB-65 >=3

›High-risk score mandates admission

›Any IDSA/ATS major criterion

›Mechanical ventilation or septic shock

›Any 3 or more IDSA/ATS minor criteria

›ICU-level admission required

›Inability to tolerate oral medications

›Unreliable outpatient follow-up or inadequate home support

ICU admission

›ICU transfer or direct ICU criteria

›Major criteria (either)

›Requirement for mechanical ventilation

›Septic shock requiring vasopressor support

›Minor criteria (>=3 of 9)

›As listed in Scoring Systems section

›Clinical judgment override

›Rapid deterioration trajectory even if criteria not yet met

Specialist consultation triggers

›In-hospital consultations

›Infectious disease consultation

›Confirmed or suspected MDR pathogen

›Immunocompromised host

›No clinical improvement at 48-72 hours

›Pulmonology consultation

08Treatment/t96

Oxygen and ventilatory support

›Supplemental oxygen titration

›Target SpO2 92%-96% in most patients

›Target 88%-92% in confirmed COPD or chronic hypercapnia

›Nasal cannula

›Maximum flow 6 L/min before stepping up

›Simple face mask or non-rebreather

›FiO2 up to 0.60 and 0.80 respectively

›High-flow nasal cannula (HFNC)

›Flow 40-60 L/min; FiO2 titrated to response

›Preferred over NIV in hypoxemic failure without hypercapnia

›Reduces intubation rate compared to conventional O2

›Non-invasive ventilation (NIV/BiPAP)

›Preferred for COPD exacerbation with hypercapnia

›Avoid if aspiration risk or altered mentation

›Invasive mechanical ventilation

›Lung-protective strategy: tidal volume 6 mL/kg ideal body weight

›Plateau pressure <30 cmH2O

›PEEP per ARDSnet protocol if P/F ratio <200 mmHg

Fluid resuscitation

›Sepsis resuscitation

›Initial crystalloid bolus

›30 mL/kg IV crystalloid (normal saline or Lactated Ringer's) for septic shock

›Reassess volume status after each 500 mL aliquot in heart failure

›Vasopressor therapy

›Norepinephrine 0.01-0.5 mcg/kg/min IV as first-line vasopressor

›Target MAP >=65 mmHg

›Vasopressin 0.03 units/min IV as second-line (norepinephrine-sparing)

›Avoid dopamine; increased arrhythmia risk vs. norepinephrine

Empiric antibiotic therapy

›No risk factors for MDR pathogens (treat as standard CAP)

›Beta-lactam plus macrolide (preferred combination)

›Ceftriaxone 1-2 g IV q24h

›Plus azithromycin 500 mg IV/PO q24h for 5 days

›Ampicillin-sulbactam 3 g IV q6h plus azithromycin 500 mg IV/PO q24h

›Respiratory fluoroquinolone monotherapy (alternative)

›Levofloxacin 750 mg IV/PO q24h for 5 days

›Contraindicated in QTc >500 ms, myasthenia gravis, tendinopathy

›Moxifloxacin 400 mg IV/PO q24h

›Risk factors for MRSA (add anti-MRSA agent)

›Vancomycin IV

›Weight-based dosing 15-20 mg/kg IV q8-12h

›Target AUC 400-600 mg*h/L (AUC-guided dosing preferred over trough)

›Loading dose 25-30 mg/kg IV for critically ill patients

›Adjust for renal function; monitor renal toxicity

›Linezolid 600 mg IV/PO q12h (alternative to vancomycin)

›Preferred for pneumonia; superior lung penetration vs. vancomycin

›Contraindicated with serotonergic agents (serotonin syndrome risk)

›Monitor CBC weekly (thrombocytopenia, anemia risk)

›Risk factors for Pseudomonas aeruginosa (antipseudomonal beta-lactam)

›Piperacillin-tazobactam 4.5 g IV q6h (extended infusion 4 hours preferred)

›Cefepime 2 g IV q8h

›Avoid in CNS disorders; neurotoxicity risk at high doses

›Meropenem 1 g IV q8h

›Preferred for ESBL-producing organisms or carbapenem-sensitive isolates

›Imipenem-cilastatin 500 mg IV q6h

›Septic shock or high-risk presentations (dual antipseudomonal coverage)

›Antipseudomonal beta-lactam (above) PLUS

›Ciprofloxacin 400 mg IV q8h as second antipseudomonal agent

›Monitor QTc and renal function

›Aminoglycoside NOT recommended as sole antipseudomonal therapy

›Add MRSA coverage with vancomycin or linezolid as above

›Suspected aspiration-related anaerobic coverage

›Ampicillin-sulbactam 3 g IV q6h (covers anaerobes and many gram-negatives)

›If broader Pseudomonas coverage needed

›Piperacillin-tazobactam 4.5 g IV q6h (anaerobic coverage included)

›Metronidazole 500 mg IV q8h added to anti-Pseudomonas regimen

›If lung abscess or empyema suspected and piperacillin-tazobactam not used

De-escalation and duration

›Antibiotic de-escalation

›Narrow spectrum within 48-72 hours based on culture results (Class I recommendation)

›Positive blood culture: target therapy to identified organism

›Positive sputum: correlate with Gram stain; discard contaminants

›Negative cultures: reassess clinical trajectory

›Clinical stability criteria for de-escalation

›Temperature trending toward normal

›Improved leukocyte count

›Improving oxygenation

›Able to take oral medications

›Treatment duration

›7-day course recommended for most HAP and HCAP regardless of pathogen (Class I, IDSA/ATS 2016)

›Procalcitonin-guided shortening acceptable if declining and stable

›Extended duration (10-14 days) for

›Pseudomonas aeruginosa or Acinetobacter baumannii

›Cavitary disease or lung abscess

›Initial bacteremia with slow clinical response

›IV to oral switch when

›Hemodynamically stable and tolerating oral intake

›Oral agent with equivalent bioavailability available

Adjunctive treatments

›Aspiration precautions

›Head-of-bed elevation >=30 degrees

›Formal swallowing evaluation before oral intake

›Speech-language pathology referral

›Oral care protocol

›Chlorhexidine 0.12% oral rinse twice daily (Class IIa, reduces VAP risk)

›Corticosteroids

›Hydrocortisone 200 mg/day IV for refractory septic shock

›Initiated when vasopressor requirement not decreasing at 48 hours

›Taper over 7-9 days when vasopressors weaning

›Not routinely indicated for HCAP without septic shock

09Special Populations/sp81

Pregnancy

›Physiological considerations

›Respiratory physiology changes

›Elevated diaphragm from uterine displacement reduces FRC

›Increased oxygen consumption and minute ventilation

›Reduced respiratory reserve; hypoxia develops faster

›Immune system alterations

›Relative immunosuppression in second and third trimester

›Increased susceptibility to influenza, varicella, Listeria

›Hemodynamic changes

›Increased cardiac output and plasma volume

›Dilutional anemia

›Antibiotic safety in pregnancy

›Safe antibiotic options

›Ceftriaxone 1-2 g IV q24h (Category B, safe in all trimesters)

›Azithromycin 500 mg IV/PO q24h (Category B, preferred macrolide)

›Ampicillin-sulbactam 3 g IV q6h (Category B)

›Vancomycin 15-20 mg/kg IV q8-12h (Category B; monitor fetal levels)

›Piperacillin-tazobactam 4.5 g IV q6h (Category B)

›Agents to avoid in pregnancy

›Fluoroquinolones: arthropathy risk in fetal cartilage; avoid unless no alternative

›Linezolid: limited data, avoid unless MDR organism with no alternative

›Aminoglycosides: fetal ototoxicity risk; avoid in second and third trimester

›Metronidazole: avoid in first trimester (teratogen concern); use with caution

›Imaging considerations

›CXR acceptable with abdominal shielding (fetal dose <1 mGy)

›CT chest: acceptable if clinical indication strong; estimated fetal dose <1 mGy

›MRI preferred over CT for mediastinal or complex evaluation

›Fetal monitoring

›Continuous fetal heart rate monitoring in third trimester

›Obstetrics consultation for all pregnant patients with pneumonia

›Preterm labor risk with sepsis; tocolytic discussion with OB

Geriatric

›Atypical presentations

›Classic fever and cough may be absent

›Falls, functional decline, or confusion as primary presentation

›Absence of fever in up to 30% of elderly patients with pneumonia

›Low threshold for CXR in elderly with unexplained functional decline

›Cognitive impairment confounds assessment

›Baseline mental status from family or care staff critical

›New confusion has high sensitivity for serious infection

›Comorbidity burden

›Polypharmacy and drug interactions

›QTc prolongation risk with fluoroquinolones plus concurrent drugs

›Vancomycin nephrotoxicity compounded by NSAIDs, diuretics

›Reduced renal clearance

›Dose-adjust antibiotics using CrCl (Cockcroft-Gault or CKD-EPI)

›Avoid nephrotoxic combinations unless no alternative

›Aspiration risk

›50% of HCAP in elderly involves aspiration risk factors

›Anaerobic coverage with ampicillin-sulbactam or piperacillin-tazobactam preferred

›Outcome considerations

›Higher mortality in HCAP vs. CAP (13-25% vs. 5-9%)

›Particularly in nursing home residents and those >80 years

›Goals of care discussion early

›Code status review and advance directive verification

›Family/SDM involvement in treatment decisions

›Functional recovery

›Hospital-acquired deconditioning and delirium prevention

›Early physiotherapy, mobility, and delirium bundle

Pediatrics

›Epidemiology in children

›HCAP less common than in adults; primarily affects

›Immunocompromised children (oncology, transplant)

›Technology-dependent children (tracheostomy, ventilator)

›Children with recurrent hospitalizations or congenital conditions

›Pathogens differ from adults

›Respiratory viruses more common (RSV, influenza, parainfluenza)

›MRSA in skin or bone source with hematogenous spread

›Gram-negative bacilli in ventilator-dependent or LTCF-residing children

›Pediatric severity assessment

›CURB-65 not validated in children; use PEWS or Respiratory Severity Score

›Tachypnea thresholds by age

›<2 months: RR >60 breaths/min

›2-12 months: RR >50 breaths/min

›1-5 years: RR >40 breaths/min

›>5 years: RR >30 breaths/min

›Antibiotic dosing in children

›Ampicillin-sulbactam 150 mg/kg/day IV divided q6h (max 12 g/day)

›Cefepime 100-150 mg/kg/day IV divided q8h (max 6 g/day)

›Vancomycin 15 mg/kg IV q6h (continuous infusion preferred in critically ill)

›Target AUC-guided dosing; trough >10 mg/L to avoid toxicity

›Avoid fluoroquinolones unless confirmed MDR with no alternative

›Ciprofloxacin 10-15 mg/kg IV q12h if necessary (max 400 mg per dose)

10Background/b89

Epidemiology

›Historical classification and current status

›HCAP as formal classification

›Defined by Niederman et al. 2005 and included in 2005 ATS/IDSA guidelines

›Community-onset pneumonia in patients with healthcare exposure

›Abandoned by 2016 IDSA/ATS HAP/VAP guidelines and 2019 ATS/IDSA CAP guidelines

›HCAP label found to be poor predictor of MDR pathogens

›Led to excessive broad-spectrum antibiotic use without mortality benefit

›Current recommended approach

›Assess individual validated risk factors for MRSA and Pseudomonas aeruginosa

›Apply local antibiogram data rather than blanket HCAP category

›Incidence and prevalence

›Community-onset pneumonia with healthcare exposure

›Estimated 200,000-300,000 cases annually in the United States

›Represents approximately 17-25% of all community-onset pneumonia admissions

›Mortality rates

›13-25% in-hospital mortality (vs. 5-9% for standard CAP)

›Nursing home-acquired pneumonia: mortality up to 30-40%

›MDR pathogen prevalence in HCAP populations

›MRSA: 3-7% of isolates in community-onset HCAP

›Pseudomonas aeruginosa: 7-19% of isolates

›MDR gram-negatives (ESBL, KPC): variable by region and antibiogram

›Healthcare exposure definitions

›Shorr HCAP criteria (defining exposures)

›Hospitalization >=2 days in past 90 days

›Nursing home or LTCF residence

›Chronic outpatient hemodialysis

›Home infusion or wound care within 30 days

Pathophysiology

›Microbiology of HCAP

›Gram-positive pathogens

›MRSA (Staphylococcus aureus methicillin-resistant)

›Community-onset MRSA (USA300 clone): Panton-Valentine leukocidin produces necrotizing pneumonia

›Healthcare-onset MRSA: biofilm-forming, device-associated

›Streptococcus pneumoniae (MDR strains increasing)

›Gram-negative pathogens

›Pseudomonas aeruginosa

›Biofilm formation in bronchiectasis and tracheostomy

›Type III secretion system causes direct cellular injury

›Carbapenem resistance via efflux pumps and porins (OprD loss)

›Klebsiella pneumoniae

›Hypervirulent strains: capsule production, liver abscess metastatic seeding

›ESBL and KPC producing strains increasingly prevalent

›Acinetobacter baumannii (mostly in ventilated patients)

›Escherichia coli and other Enterobacteriaceae

›Aspiration-related pathogens

›Oral anaerobes: Bacteroides, Prevotella, Fusobacterium, Peptostreptococcus

›Often polymicrobial with gram-negative bacilli

›Mechanisms of infection

›Microaspiration of oropharyngeal contents

›Primary mechanism in LTCF and hospitalized patients

›Altered consciousness, dysphagia, or impaired cough increases risk

›Colonization of oropharynx with gram-negative bacilli precedes infection

›Hematogenous seeding (less common)

›Dialysis access site bacteremia with secondary lung seeding

›Direct inhalation

›Aerosol-generating procedures in healthcare settings

›Host defense impairment

›Mucociliary clearance reduction

›Smoking, COPD, mechanical ventilation impair ciliary function

›Dehydration reduces mucus viscosity clearance

›Cellular immunity defects

›Neutropenia (chemotherapy, leukemia)

›Lymphopenia (HIV, transplant immunosuppression)

›Macrophage dysfunction in diabetes and uremia

Therapeutic Considerations

›Antibiotic stewardship principles

›De-escalation mandate

›Narrow within 48-72 hours when cultures available (Class I recommendation, IDSA/ATS 2016)

›Reduces C. difficile risk, MDR emergence, and toxicity

›Failure to de-escalate common practice failure in HCAP management

›7-day therapy rule

›Non-inferior to longer courses for HAP/VAP (IDSA/ATS 2016)

›Exception: necrotizing pneumonia, Pseudomonas, or slow clinical response

›Avoid aminoglycosides as monotherapy

›Inadequate lung penetration

›Reserve for combination therapy in severe Pseudomonas infections

›Culture-guided therapy

›Importance of respiratory specimens

›Pretherapy sputum or BAL culture essential for de-escalation guidance

›Molecular panels increasingly replace or supplement culture

›Blood culture yield

›20-35% in pneumonia; alters management when positive

›Critical for identifying MRSA bacteremia requiring extended therapy

›HCAP vs. CAP reclassification impact

›Studies showing equivalent CAP treatment in low-risk HCAP

›Attridge and Frei 2011: most HCAP patients respond to CAP regimens

›Risk-stratified approach superior to uniform broadening

›Pharmacokinetic considerations in HCAP

›Vancomycin AUC/MIC-guided dosing superior to trough-only monitoring

›Extended-infusion beta-lactams improve pharmacodynamic target attainment

›Critically ill patients: volume of distribution increased, drug levels unpredictable

11Patient Discharge Instructions/pdi35

copy discharge instructions

›Healthcare-Associated Pneumonia: Instructions for Home Recovery

›Your diagnosis

›You were treated for pneumonia (lung infection)

›You received antibiotics in hospital and/or a prescription to continue at home

›Take all antibiotics exactly as prescribed, even if you feel better; do not stop early

›Activity and recovery

›Rest as needed; return to activity gradually as your breathing improves

›Full recovery may take 4-8 weeks; feeling tired is normal

›Deep breathing exercises 10 times per hour when awake help clear your lungs

›Eating and drinking

›Drink plenty of fluids (8-10 glasses of water daily) to thin mucus

›Sit upright during and for 30 minutes after meals to reduce aspiration risk

›If you have difficulty swallowing, do not eat or drink until evaluated by your doctor

›Medications at home

›Complete the full antibiotic course as directed

›Do not take new medications (including herbal supplements) without asking your doctor

›Take medications to manage fever (acetaminophen or ibuprofen) as directed

›Follow-up appointments

›See your family doctor or specialist within 1-2 weeks of discharge

›A repeat chest X-ray in 6-8 weeks is recommended to confirm your lungs have healed

›This is especially important if you are a smoker aged over 50 to rule out other causes

›Preventing future pneumonia

›Pneumococcal vaccine (Prevnar 20 or Pneumovax 23): if not received, ask your doctor

›Influenza vaccine annually

›Oral hygiene: brush teeth twice daily and use antiseptic mouthwash

›Quit smoking: most important modifiable risk factor for lung infections

›When to return to emergency department immediately

12References/r36

Guidelines and key sources

›IDSA/ATS Community-Acquired Pneumonia Guidelines 2019

›Metlay JP, Waterer GW, Long AC, et al.

›Diagnosis and Treatment of Adults With Community-Acquired Pneumonia

›American Journal of Respiratory and Critical Care Medicine 2019

›Key recommendation: abandon HCAP category; use individual MDR risk factor assessment

›IDSA/ATS Hospital-Acquired and Ventilator-Associated Pneumonia Guidelines 2016

›Kalil AC, Metersky ML, Klompas M, et al.

›Management of Adults With Hospital-Acquired and Ventilator-Associated Pneumonia

›Clinical Infectious Diseases 2016; doi: 10.1093/cid/ciw353

›Key recommendation: 7-day treatment duration; de-escalation within 48-72 hours

›Shorr MDR Risk Score

›Shorr AF, Zilberberg MD, Micek ST, Kollef MH.

›Prediction of Infection Due to Antibiotic-Resistant Bacteria by Select Risk Factors for HCAP

›Archives of Internal Medicine 2008; 168(20):2205-10

›HCAP evidence review

›Attridge RT, Frei CR.

›Health Care-Associated Pneumonia: An Evidence-Based Review

›American Journal of Medicine 2011; 124(7):689.e1-689.e10

›Severity scoring in HCAP

›Fang WF, Yang KY, Wu CL, et al.

›Application and Comparison of Scoring Indices to Predict Outcomes in HCAP

›Critical Care 2011; 15(1):R32

›Noguchi S, Yatera K, Kawanami T, et al.

›Pneumonia Severity Assessment Tools for HCAP: Systematic Review and Meta-Analysis

›Respiration 2016; 91(1):16-27

›Microbiology laboratory diagnostics

›Miller JM, Binnicker MJ, Campbell S, et al.

Evidence & Review