Hospital‑Acquired and Ventilator‑Associated Pneumonia Management

Empiric Antibiotic Selection

• Empiric therapy for hospital‑acquired pneumonia (HAP) must be stratified by the presence or absence of multidrug‑resistant (MDR) risk factors; prompt initiation of appropriate antibiotics is essential to reduce mortality. [1][2]

MDR Risk Factors (Late‑Onset, High‑Risk)

• Hospitalization for ≥ 5 days before pneumonia onset identifies patients who require broad‑spectrum empiric coverage. [1][2]
• Intravenous antibiotic use within the prior 90 days is a MDR risk factor. [1][2]
• Admission from a health‑care associated facility (e.g., nursing home, dialysis center, long‑term care) mandates MDR‑covering therapy. [1][2]
• Immunosuppressive disease or therapy also confers MDR risk. 3

Antibiotic Regimens

Low‑Risk (Early‑Onset) Monotherapy

• In patients without MDR risk factors, monotherapy targeting Streptococcus pneumoniae, Haemophilus influenzae, methicillin‑susceptible S. aureus, and antibiotic‑sensitive gram‑negative enteric organisms is appropriate. Recommended agents include ceftriaxone, levofloxacin, ciprofloxacin, ampicillin‑sulbactam, and ertapenem. 3

High‑Risk (Late‑Onset) Combination Therapy

• Patients with MDR risk factors require combination therapy that covers Pseudomonas aeruginosa, ESBL‑producing organisms, Acinetobacter spp., and MRSA. [1][2]3

Core Antipseudomonal β‑Lactam (choose ONE)

• Acceptable agents are piperacillin‑tazobactam, cefepime, ceftazidime, meropenem, or imipenem. Each provides antipseudomonal activity and should be selected based on local susceptibility patterns. [1][2]3

Second Antipseudomonal Agent (choose ONE)

• Add a second antipseudomonal drug such as levofloxacin, ciprofloxacin, amikacin, or gentamicin/tobramycin to achieve synergistic coverage. [1][2]3

Anti‑MRSA Coverage (if MRSA risk present)

• Include vancomycin or linezolid for MRSA empiric coverage. [1][2]

Ventilator‑Associated Pneumonia (VAP) Specific Considerations

Diagnostic Sampling

• Obtain lower‑respiratory‑tract specimens (bronchoalveolar lavage, protected specimen brush, or endotracheal aspirate) for quantitative cultures before starting antibiotics whenever feasible. 1

Timing of Therapy

• In clinically unstable patients, do not delay antibiotics while awaiting diagnostics; delays increase mortality. Empiric therapy should be started within the first hour of suspicion. [1][2]
• Inappropriate initial therapy (pathogen not susceptible to the regimen) markedly raises mortality; delayed appropriate therapy (> 24 h) further worsens outcomes. [1][2]

De‑escalation and Duration

De‑escalation Strategy (48–72 h)

• Narrow the antibiotic regimen based on culture results and clinical response after 48–72 h.
• If cultures are negative and the patient is improving, stop antibiotics or switch to standard therapy. 4
• Discontinue vancomycin or linezolid when MRSA is not isolated. [4][2]
• De‑escalate from antipseudomonal agents to narrower‑spectrum drugs when Pseudomonas is not isolated. [4][2]
• Transition from combination therapy to monotherapy when susceptibilities allow. 2

Recommended Treatment Duration

• Limit therapy to 7–8 days for patients who respond adequately. 2
• Extend beyond 7 days only for persistent fever, lack of radiographic improvement, or continued purulent sputum. 2

Institutional Protocols and Outcomes

• Each ICU should develop institution‑specific protocols based on local antibiograms and update them regularly. 2
• Protocol‑driven therapy has been shown to increase the proportion of patients receiving appropriate initial antibiotics, reduce total antimicrobial duration, and lower antibiotic costs. 2

Common Pitfalls

• Delaying antibiotic initiation in unstable patients while awaiting diagnostics increases mortality. [1][2]
• Continuing the same antibiotic class as recent therapy raises the risk of resistance and inappropriate coverage. 2
• Using monotherapy in high‑risk MDR patients leads to treatment failure.
• Providing unnecessary broad‑spectrum coverage to low‑risk patients promotes resistance.
• Failing to de‑escalate after 48–72 h when cultures are negative or show susceptible organisms. [4][2]
• Prolonging therapy beyond 7–8 days in patients who are clinically improving without a documented indication. 2

Hospital-Acquired Pneumonia Treatment Guidelines

Introduction to Empiric Antibiotic Therapy

• The Infectious Diseases Society of America recommends empiric antibiotic therapy for hospital-acquired pneumonia should be stratified based on risk factors for mortality and multidrug-resistant pathogens, with piperacillin-tazobactam as the backbone for most regimens 5, 6, 7

Risk Stratification for Empiric Therapy

• For low-risk patients, the American Thoracic Society suggests monotherapy with one of the following options: Cefepime 2 g IV q8h, Levofloxacin 750 mg IV daily, or Ciprofloxacin 400 mg IV q8h 6
• For moderate-risk patients, the Infectious Diseases Society of America recommends monotherapy with one of the following options: Cefepime or ceftazidime 2 g IV q8h, Levofloxacin 750 mg IV daily, Ciprofloxacin 400 mg IV q8h, or Aztreonam 2 g IV q8h (if severe penicillin allergy) 6
• For moderate-risk patients, the Infectious Diseases Society of America suggests adding MRSA coverage with Linezolid 600 mg IV q12h 6
• For high-risk patients, the American Thoracic Society recommends dual antipseudomonal coverage with two of the following: Cefepime or ceftazidime 2 g IV q8h, Levofloxacin 750 mg IV daily, Ciprofloxacin 400 mg IV q8h, Amikacin 15-20 mg/kg IV daily, or Aztreonam 2 g IV q8h (if severe penicillin allergy) 5, 6, 7
• For high-risk patients, the Infectious Diseases Society of America suggests adding MRSA coverage with Linezolid 600 mg IV q12h 6

Risk Factors to Consider

• The Infectious Diseases Society of America identifies need for ventilatory support due to pneumonia and septic shock as risk factors for mortality 5, 6, 7
• The American Thoracic Society identifies intravenous antibiotic treatment during the prior 90 days, treatment in a unit where MRSA prevalence among S. aureus isolates is >20% or unknown, and prior detection of MRSA by culture or screening as risk factors for MRSA 5, 6, 7

Special Considerations

• For confirmed methicillin-sensitive S. aureus (MSSA), the Infectious Diseases Society of America recommends narrowing to oxacillin, nafcillin, or cefazolin (preferred over broader agents) 5, 7
• For severe penicillin allergy, the American Thoracic Society suggests using aztreonam but ensuring MSSA coverage is maintained 5, 7

Common Pitfalls to Avoid

• The Infectious Diseases Society of America warns against using inappropriate monotherapy in high-risk patients who require combination therapy, and against the unnecessary use of broad-spectrum antibiotics in low-risk patients, which contributes to antimicrobial resistance 5, 6, 7
• The American Thoracic Society recommends adjusting therapy based on culture results and clinical response 5, 6, 7

Renal Dosing of Cefepime for Hospital-Acquired Pneumonia

Empiric Coverage Considerations

• The Infectious Diseases Society of America recommends cefepime 2 grams IV every 8 hours for hospital-acquired pneumonia in patients with normal renal function, but for dialysis patients, a reduced dosing schedule may be necessary to avoid toxicity, and consider adding a second antipseudomonal agent in high-risk patients 8
• The American Thoracic Society suggests that combination therapy with a second antipseudomonal agent, such as a fluoroquinolone or aminoglycoside, improves outcomes in severe hospital-acquired pneumonia, even in dialysis patients, and cefepime dosing should be adjusted accordingly 8

IV Levofloxacin Dosing and Combination Therapy for Hospital‑Acquired Pneumonia Caused by Pseudomonas aeruginosa

Dosing Recommendations

• In adults with hospital‑acquired pneumonia (HAP) due to P. aeruginosa and normal renal function, administer levofloxacin 750 mg intravenously once daily as part of combination therapy; a 7–8 day course is appropriate when clinical response is adequate. 9

Combination Therapy Requirements

• Levofloxacin must never be used as monotherapy for P. aeruginosa HAP; dual antipseudomonal coverage is required to avoid treatment failure and resistance. 9
• The fluoroquinolone should be paired with one antipseudomonal β‑lactam. Recommended β‑lactam agents and standard dosing are:

• In high‑risk patients (mechanically ventilated, septic shock, or hemodynamically unstable), dual antipseudomonal coverage significantly reduces treatment failure and mortality. 9

Risks of Levofloxacin Monotherapy

• Using levofloxacin alone for P. aeruginosa HAP leads to higher rates of treatment failure and promotes antimicrobial resistance. 9

Duration of Therapy (Evidence‑Based Guidance)

• A standard treatment duration of 7–8 days is recommended when the patient shows an adequate clinical response; extension beyond this period should be reserved for persistent fever, lack of radiographic improvement, or ongoing purulent sputum production. This recommendation is derived from the same citation supporting the dosing regimen. 9

Oral Antibiotic Strategies for MSSA Pneumonia

Guideline Evidence Gap

• The 2011 IDSA MRSA guideline notes limited data on oral antibiotics for staphylococcal pneumonia, with the only published experience involving oral ciprofloxacin + rifampin in MSSA right‑sided endocarditis (not pneumonia)【10】.
• IDSA guidance advises that transition from parenteral to oral therapy should be done cautiously and only in uncomplicated bacteremia, a caution that extends to MSSA pneumonia due to the lack of robust trial data【10】.
• The 2016 IDSA/ATS hospital‑acquired pneumonia guideline recommends intravenous oxacillin, nafcillin, or cefazolin as preferred agents for proven MSSA pneumonia, and provides no oral equivalents with comparable efficacy【11】.

Oral Therapy Options (Limited Evidence)

• Clindamycin 600 mg PO three times daily is the most evidence‑supported oral option when the isolate is susceptible and local clindamycin‑resistance rates are <10%【10】 (expert opinion, limited data).
• Clindamycin attains good lung penetration and has been used successfully in pediatric MSSA pneumonia after initial IV therapy【10】 (case series).
• Fluoroquinolone + rifampin: oral ciprofloxacin + rifampin has been reported only in MSSA endocarditis; data for pneumonia are essentially nonexistent【10】 (expert opinion).
• Moxifloxacin 400 mg PO daily shows better S. aureus activity than ciprofloxacin and achieves excellent lung concentrations, but monotherapy risks resistance emergence; therefore rifampin should be added when a fluoroquinolone is used【10】 (expert opinion).
• Linezolid 600 mg PO twice daily has excellent oral bioavailability and lung penetration and is FDA‑approved for MRSA pneumonia, but it is costly and generally reserved for MRSA rather than MSSA infections【10】 (expert opinion).

Treatment Duration

• Recommended total duration for MSSA pneumonia is 7–21 days, with most uncomplicated cases treated for 7–10 days【10】 (guideline recommendation).
• When oral therapy is employed, it should constitute the tail end of treatment after IV therapy has achieved clinical response【10】.

Clinical Decision Criteria for IV‑to‑Oral Switch

• Confirm susceptibility of the MSSA isolate to the planned oral agent, especially performing a D‑test for inducible clindamycin resistance【10】.
• Rule out complications such as empyema, lung abscess, necrotizing pneumonia, ongoing bacteremia, or any intravascular infection before considering oral therapy【10】.

Common Pitfalls

• Assuming all oral antibiotics are equivalent for staphylococcal pneumonia; clindamycin is the only oral agent with reasonable supporting data【10】.
• Using ciprofloxacin monotherapy is inappropriate because of poor activity against S. pneumoniae and the risk of resistance; if a fluoroquinolone is used for MSSA, it must be combined with rifampin【10】.
• Premature oral switch before achieving clinical stability increases the risk of treatment failure and relapse【10】.
• Neglecting MSSA prevalence: MSSA pneumonia is uncommon in community‑acquired settings; microbiologic confirmation is essential before committing to prolonged anti‑staphylococcal therapy【10】【11】.

Bottom‑Line Recommendation

• IV therapy remains the standard of care for MSSA pneumonia due to the paucity of oral data.
• If oral transition is deemed necessary after clinical stabilization, clindamycin 600 mg PO three times daily (provided the isolate is susceptible) is the most defensible choice; fluoroquinolone + rifampin may be considered as a secondary, off‑label option with very limited evidence【10】.
• Close monitoring is mandatory; any clinical deterioration should prompt immediate return to IV therapy【10】.

Empiric Dual Antipseudomonal and Anti‑MRSA Therapy for High‑Risk Hospital‑Acquired/Ventilator‑Associated Pneumonia after Prior Antibiotic Failure

Risk Assessment for Multidrug‑Resistant (MDR) Pathogens

• Prior exposure to broad‑spectrum antibiotics within the preceding 90 days is the single strongest predictor of infection with MDR organisms, warranting empiric MDR‑directed therapy. Strong predictor – European Respiratory Society (ERS) guideline. 12, 13
• Hospitalization of ≥5 days before pneumonia onset mandates coverage for MDR pathogens in the empiric regimen. Strong recommendation – ERS guideline. 12, 13
• Failure of carbapenem therapy (e.g., meropenem) signals a high likelihood of carbapenem‑resistant Enterobacteriaceae, extensively drug‑resistant Pseudomonas aeruginosa, or carbapenem‑resistant Acinetobacter baumannii. High‑risk indicator – ERS guideline. 12, 13

Empiric Antimicrobial Recommendations

Core Gram‑Negative Coverage

• Cefiderocol 2 g IV every 8 h (3‑hour infusion) is recommended as the primary anti‑Gram‑negative agent because it retains activity against carbapenem‑resistant Enterobacteriaceae, ESBL‑producing, and MDR Pseudomonas/Acinetobacter that have failed prior therapy. Strong recommendation – ERS guideline. 12, 13

Mandatory Second Antipseudomonal Agent

• Adding an aminoglycoside (e.g., amikacin 15–20 mg/kg IV once daily) to cefiderocol is strongly recommended for high‑risk HAP/VAP to ensure at least one active antipseudomonal drug. Strong recommendation – ERS guideline. 12, 13
• Aminoglycosides provide synergistic bactericidal activity with β‑lactams and suppress emergence of resistance during therapy. Evidence of synergy – American Thoracic Society (ATS) guideline. 14
• Regimens that include an aminoglycoside show a trend toward improved patient survival compared with fluoroquinolone‑based combinations. Trend toward better outcomes – ATS guideline. 14

Mandatory Anti‑MRSA Coverage

• Empiric MRSA coverage (vancomycin 15 mg/kg IV q8–12 h targeting trough 15–20 µg/mL or linezolid 600 mg IV q12 h) is required when prior broad‑spectrum antibiotic exposure occurred within 90 days. Strong recommendation – ERS guideline. 12, 13
• An ICU MRSA prevalence >20 % (or unknown prevalence) also mandates empiric anti‑MRSA therapy. Strong recommendation – ERS guideline. 12, 13

Diagnostic and De‑escalation Strategies

• Obtain lower‑respiratory‑tract cultures (BAL, protected specimen brush, or quantitative endotracheal aspirate) before initiating the empiric regimen. Strong recommendation – ERS guideline. 12, 13
• Reassess antimicrobial therapy at 48–72 h using culture results and clinical parameters (temperature, respiratory rate, oxygenation, hemodynamics). Strong recommendation – ERS & Intensive Care Society (ICS) guideline. 12, 13, 15
• Discontinue vancomycin or linezolid if MRSA is not isolated. Strong recommendation – ERS guideline. 12, 13
• If cultures identify a susceptible organism and the patient is improving, de‑escalate to monotherapy. Strong recommendation – ERS & ICS guideline. 12, 13, 15
• Maintain combination therapy only when XDR/PDR organisms (susceptible to ≤2 antibiotic classes) or CRE are isolated. Strong recommendation – ERS guideline. 12, 13

Treatment Duration

• Standard therapy duration is 7–8 days for patients with an adequate clinical response. Strong recommendation – ERS & ICS guideline. 12, 15
• Extend therapy beyond 7 days only if persistent fever, lack of radiographic improvement, or ongoing purulent sputum are present. Conditional recommendation – ERS guideline. 12

Common Pitfalls to Avoid

• Re‑using antibiotic classes that have already failed (fluoroquinolones, cephalosporins, carbapenems) selects resistant mutants and guarantees treatment failure. Strong warning – ERS guideline. 12, 13
• Employing monotherapy in high‑risk patients leads to inadequate coverage and increased mortality. Strong warning – ERS & ATS guideline. 12, 13, 14
• Omitting MRSA coverage despite prior broad‑spectrum antibiotic exposure is inappropriate when MRSA risk factors are present. Strong warning – ERS guideline. 12, 13
• Delaying respiratory cultures impairs timely de‑escalation and prolongs unnecessary broad‑spectrum exposure. Strong warning – ERS guideline. 12, 13

Alternative Regimens (When Cefiderocol Unavailable)

• Colistin (polymyxin E) 5 mg/kg loading dose then 2.5 mg/kg IV q12 h plus an aminoglycoside can be used, but it carries higher nephro‑ and neuro‑toxicity. Conditional use – ERS guideline. 12, 13
• Aztreonam 2 g IV q8 h plus an aminoglycoside is an alternative, though it lacks activity against Acinetobacter and provides no MSSA coverage, requiring additional anti‑MRSA therapy. Conditional use – ERS guideline. 12, 13

Pharmacodynamic Optimization

• Administer β‑lactams (including cefiderocol) as extended infusions (e.g., 3‑hour infusion) to optimize pharmacodynamic exposure in septic shock or severe infection. Strong recommendation – Intensive Care Society (ICS) guideline. 15

Guideline Recommendations for Antibiotic Selection in Severe Hospital‑Acquired and Ventilator‑Associated Pneumonia

1. Comparative Coverage of the Two Regimens

• Piperacillin‑tazobactam provides superior single‑agent coverage compared with cefepime + metronidazole for severe HAP/VAP, especially against anaerobic organisms and certain resistant Gram‑negative pathogens. 16
• Both regimens achieve equivalent antipseudomonal activity; standard dosing (cefepime 2 g IV q8 h, piperacillin‑tazobactam 4.5 g IV q6 h) yields comparable efficacy against Pseudomonas aeruginosa in nosocomial pneumonia. 16
• For severe P. aeruginosa pneumonia, dual antipseudomonal therapy is required—either agent should be combined with a fluoroquinolone or an aminoglycoside. 16

2. Gram‑Negative Pathogen Considerations

• Piperacillin‑tazobactam is FDA‑approved for nosocomial pneumonia caused by Acinetobacter baumannii, whereas cefepime lacks this specific indication. 16
• Cefepime is preferred when Enterobacter species or other AmpC‑producing organisms are suspected, particularly in ICUs with a high prevalence of these pathogens. 16
• Institutional antibiograms that demonstrate higher susceptibility of local Gram‑negative isolates to cefepime support choosing cefepime + metronidazole over piperacillin‑tazobactam. 16

3. Gram‑Positive Pathogen Considerations

• Neither regimen covers MRSA; vancomycin or linezolid must be added when MRSA risk factors (e.g., prior colonization, high ICU prevalence, recent broad‑spectrum antibiotics) are present. 16
• Both agents provide excellent coverage of Streptococcus pneumoniae, including penicillin‑resistant strains. 16

4. Anaerobic Coverage

• Metronidazole reliably covers the Bacteroides fragilis group; cefepime alone has minimal activity against these anaerobes and therefore requires metronidazole when anaerobic infection is documented. 16
• Piperacillin‑tazobactam intrinsically covers anaerobes, eliminating the need for a separate anaerobic agent in most cases. 16
• Current guidelines advise against routine anaerobic coverage for suspected aspiration pneumonia unless a lung abscess or empyema is confirmed; when coverage is needed, piperacillin‑tazobactam monotherapy is preferred over cefepime + metronidazole. 16

5. Indications for Selecting Each Regimen

• Piperacillin‑tazobactam is indicated for nosocomial pneumonia with a risk of Acinetobacter (ICU setting, prolonged hospitalization, recent broad‑spectrum antibiotics) or when a documented lung abscess/empyema requires anaerobic coverage without a β‑lactam allergy. 16
• Cefepime + metronidazole is indicated when Enterobacter or AmpC‑producing organisms are suspected, when a β‑lactam allergy precludes piperacillin‑tazobactam (with aztreonam as an alternative β‑lactam), or when local susceptibility data favor cefepime. 16

6. Dosing Recommendations

• Cefepime: 2 g IV every 8 hours (30‑minute infusion) for severe pneumonia or pseudomonal infection. 16
• Metronidazole (when needed): 500 mg IV every 8 hours.
• Piperacillin‑tazobactam: 4.5 g IV every 6 hours (30‑minute infusion) for nosocomial pneumonia; extended infusion over 3–4 hours may improve pharmacodynamics in critically ill patients. 16

7. Duration of Therapy

• Standard treatment duration is 7–8 days for patients with an adequate clinical response (afebrile 48–72 h, hemodynamically stable, improving oxygenation). 16
• Extend therapy beyond 7 days for persistent fever or lack of radiographic improvement, ongoing purulent sputum, or when infection with Legionella, Staphylococcus aureus, or Gram‑negative enteric bacilli warrants 14–21 days. 16

8. De‑escalation and Reassessment

• Reassess antimicrobial regimen at 48–72 hours using culture results and clinical response. 16
• Discontinue metronidazole if anaerobic organisms are not isolated and no abscess/empyema is present. 16
• Narrow from piperacillin‑tazobactam to a narrower β‑lactam (e.g., ceftriaxone or cefepime) when susceptibilities allow and Pseudomonas is excluded. 16
• Stop vancomycin or linezolid when MRSA is not identified. 16

9. Common Pitfalls to Avoid

• Do not add metronidazole to cefepime routinely; reserve it for documented lung abscess, empyema, or necrotizing infection. 16
• Do not use monotherapy with either agent in high‑risk HAP/VAP (septic shock, mechanical ventilation, prior antibiotic failure); dual antipseudomonal coverage is required. 16
• Do not continue broad‑spectrum therapy beyond 7–8 days in patients who are responding without specific indications, to reduce resistance and Clostridioides difficile risk. 16
• Do not assume piperacillin‑tazobactam covers MRSA; add vancomycin or linezolid when MRSA risk factors are present. 16

Empiric Management of Hospital‑Acquired Pneumonia Involving Pseudomonas aeruginosa and MRSA

Meropenem Combination Therapy for Severe Pseudomonas Pneumonia

• For critically ill patients with hospital‑acquired pneumonia caused by P. aeruginosa, meropenem must be combined with a second anti‑pseudomonal agent from a different class (e.g., levofloxacin 750 mg IV daily, ciprofloxacin 400 mg IV q8 h, or an aminoglycoside such as amikacin 15–20 mg/kg IV daily). This strategy reduces rapid emergence of resistance. [17][18]

Meropenem Dosing

• The recommended regimen for hospital‑acquired pneumonia is meropenem 1 g IV every 8 hours, administered by a 15–30‑minute infusion. [17][18]

Risk Assessment for MRSA Pneumonia

• Key predictors that should trigger empirical MRSA coverage:
• Additional risk factors for ventilator‑associated pneumonia (VAP) include septic shock at VAP onset, preceding ARDS, ≥5 days of hospitalization before VAP, and prior acute renal replacement therapy. 18

Empiric Anti‑MRSA Therapy

• Vancomycin 15 mg/kg IV every 8–12 h (target trough 15–20 µg/mL; loading dose 25–30 mg/kg for severe disease) or Linezolid 600 mg IV every 12 h should be used when MRSA coverage is indicated. [17][18]
• Both agents receive a strong recommendation with moderate‑quality evidence for empirical MRSA treatment. 18

Decision Algorithm for Empiric Antimicrobial Coverage

• Patients without MRSA risk factors and without high‑mortality features: use an anti‑S. aureus (MSSA) regimen such as piperacillin‑tazobactam, cefepime, levofloxacin, imipenem, or meropenem (alone or with a second anti‑pseudomonal agent). [17][18]
• Patients with any MRSA risk factor or high‑mortality features: add vancomycin or linezolid to the anti‑pseudomonal regimen (e.g., meropenem + fluoroquinolone + vancomycin). [17][18]

De‑escalation and Antimicrobial Stewardship

• Discontinue vancomycin or linezolid after 48–72 h if respiratory cultures do not isolate MRSA. 18
• Avoid continuing anti‑MRSA agents beyond 48–72 h when cultures are negative and the patient is clinically improving. 18

Common Pitfalls to Avoid

• Do not omit anti‑MRSA coverage when the above risk factors are present, especially after recent broad‑spectrum antibiotic use.
• Do not assume that anti‑pseudomonal β‑lactams (meropenem, piperacillin‑tazobactam, cefepime) provide MRSA coverage; they are active only against MSSA. 17
• Do not rely on monotherapy in high‑risk patients; combination anti‑pseudomonal therapy plus anti‑MRSA coverage is required.