Empiric antibiotic selection and risk prediction of drug-resistant pathogens in community-onset pneumonia

Stewardship Prompts to Improve Antibiotic Selection for Pneumonia: The INSPIRE Randomized Clinical Trial

Importance

Pneumonia is the most common infection requiring hospitalization and is a major reason for overuse of extended-spectrum antibiotics. Despite low risk of multidrug-resistant organism (MDRO) infection, clinical uncertainty often drives initial antibiotic selection. Strategies to limit empiric antibiotic overuse for patients with pneumonia are needed.

Objective

To evaluate whether computerized provider order entry (CPOE) prompts providing patient- and pathogen-specific MDRO infection risk estimates could reduce empiric extended-spectrum antibiotics for non-critically ill patients admitted with pneumonia.

Design, Setting, and Participants

Cluster-randomized trial in 59 US community hospitals comparing the effect of a CPOE stewardship bundle (education, feedback, and real-time MDRO risk-based CPOE prompts; n = 29 hospitals) vs routine stewardship (n = 30 hospitals) on antibiotic selection during the first 3 hospital days (empiric period) in non-critically ill adults (≥18 years) hospitalized with pneumonia. There was an 18-month baseline period from April 1, 2017, to September 30, 2018, and a 15-month intervention period from April 1, 2019, to June 30, 2020.

Intervention

CPOE prompts recommending standard-spectrum antibiotics in patients ordered to receive extended-spectrum antibiotics during the empiric period who have low estimated absolute risk (<10%) of MDRO pneumonia, coupled with feedback and education.

Main Outcomes and Measures

The primary outcome was empiric (first 3 days of hospitalization) extended-spectrum antibiotic days of therapy. Secondary outcomes included empiric vancomycin and antipseudomonal days of therapy and safety outcomes included days to intensive care unit (ICU) transfer and hospital length of stay. Outcomes compared differences between baseline and intervention periods across strategies.

Results

Among 59 hospitals with 96 451 (51 671 in the baseline period and 44 780 in the intervention period) adult patients admitted with pneumonia, the mean (SD) age of patients was 68.1 (17.0) years, 48.1% were men, and the median (IQR) Elixhauser comorbidity count was 4 (2-6). Compared with routine stewardship, the group using CPOE prompts had a 28.4% reduction in empiric extended-spectrum days of therapy (rate ratio, 0.72 [95% CI, 0.66-0.78]; P < .001). Safety outcomes of mean days to ICU transfer (6.5 vs 7.1 days) and hospital length of stay (6.8 vs 7.1 days) did not differ significantly between the routine and CPOE intervention groups.

Conclusions and Relevance

Empiric extended-spectrum antibiotic use was significantly lower among adults admitted with pneumonia to non-ICU settings in hospitals using education, feedback, and CPOE prompts recommending standard-spectrum antibiotics for patients at low risk of MDRO infection, compared with routine stewardship practices. Hospital length of stay and days to ICU transfer were unchanged.

Trial Registration

ClinicalTrials.gov Identifier: NCT03697070.

New Guidelines for Severe Community-acquired Pneumonia

In 2023, the new European guidelines on severe community-acquired pneumonia, providing clinical practice recommendations for the management of this life-threatening infection, characterized by a high burden of mortality, morbidity, and costs for the society. This review article aims to summarize the principal evidence related to eight different questions covered in the guidelines, by also highlighting the future perspectives for research activity.

Antibiotic Strategies for Severe Community-Acquired Pneumonia

Despite advancements in health systems and intensive care unit (ICU) care, along with the introduction of novel antibiotics and microbiologic techniques, mortality rates in severe community-acquired pneumonia (sCAP) patients have not shown significant improvement. Delayed admission to the ICU is a major risk factor for higher mortality. Apart from choosing the appropriate site of care, prompt and appropriate antibiotic therapy significantly affects the prognosis of sCAP. Treatment regimens involving ceftaroline or ceftobiprole are currently considered the best options for managing patients with sCAP. Additionally, several other molecules, such as delafloxacin, lefamulin, and omadacycline, hold promise as therapeutic strategies for sCAP. This review aims to provide a comprehensive summary of the key challenges in managing adults with severe CAP, focusing on essential aspects related to antibiotic treatment and investigating potential strategies to enhance clinical outcomes in sCAP patients.

ICU Utilization After Implementation of Minor Severe Pneumonia Criteria in Real-Time Electronic Clinical Decision Support

OBJECTIVES

To determine if the implementation of automated clinical decision support (CDS) with embedded minor severe community-acquired pneumonia (sCAP) criteria was associated with improved ICU utilization among emergency department (ED) patients with pneumonia who did not require vasopressors or positive pressure ventilation at admission.

DESIGN

Planned secondary analysis of a stepped-wedge, cluster-controlled CDS implementation trial.

SETTING

Sixteen hospitals in six geographic clusters from Intermountain Health; a large, integrated, nonprofit health system in Utah and Idaho.

PATIENTS

Adults admitted to the hospital from the ED with pneumonia identified by: 1) discharge International Classification of Diseases , 10th Revision codes for pneumonia or sepsis/respiratory failure and 2) ED chest imaging consistent with pneumonia, who did not require vasopressors or positive pressure ventilation at admission.

INTERVENTIONS

After implementation, patients were exposed to automated, open-loop, comprehensive CDS that aided disposition decision (ward vs. ICU), based on objective severity scores (sCAP).

MEASUREMENTS AND MAIN RESULTS

The analysis included 2747 patients, 1814 before and 933 after implementation. The median age was 71, median Elixhauser index was 17, 48% were female, and 95% were Caucasian. A mixed-effects regression model with cluster as the random effect estimated that implementation of CDS utilizing sCAP increased 30-day ICU-free days by 1.04 days (95% CI, 0.48-1.59; p < 0.001). Among secondary outcomes, the odds of being admitted to the ward, transferring to the ICU within 72 hours, and receiving a critical therapy decreased by 57% (odds ratio [OR], 0.43; 95% CI, 0.26-0.68; p < 0.001) post-implementation; mortality within 72 hours of admission was unchanged (OR, 1.08; 95% CI, 0.56-2.01; p = 0.82) while 30-day all-cause mortality was lower post-implementation (OR, 0.71; 95% CI, 0.52-0.96; p = 0.03).

CONCLUSIONS

Implementation of electronic CDS using minor sCAP criteria to guide disposition of patients with pneumonia from the ED was associated with safe reduction in ICU utilization.

Methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa community acquired pneumonia: Prevalence and locally derived risk factors in a single hospital system

Objectives

Current American Thoracic Society/Infectious Disease Society of America (ATS/IDSA) community-acquired pneumonia (CAP) guidelines expand the CAP definition to include infections occurring in patients with recent health care exposure. The guidelines now recommend that hospital systems determine their own local prevalence and predictors of Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus (MRSA) among patients satisfying this new broader CAP definition. We sought to carry out these recommendations in our system, focusing on the emergency department, where CAP diagnosis and initial empiric antibiotic selection usually ooccur.

Methods

We performed a retrospective cohort study of patients admitted with CAP through any of 3 EDs in our hospital system in Northern California between November 2019 and October 2021. Inclusion criteria included an ED admission diagnosis of pneumonia or sepsis, fever or hypothermia, leukocytosis or leukopenia, and consistent chest imaging result. SARS-CoV-2-positive cases were excluded. We abstracted variables historically associated with P. aeruginosa and MRSA. Outcome measures were prevalence of P. aeruginosa and MRSA in the overall clinically defined cohort and among microbiologically confirmed cases and predictors of P. aeruginosa or MRSA isolation, as determined by univariate logistic regression, bootstrapped least absolute shrinkage and selection operator, and random forest analyses. Additionally, we describe the iterative process used and challenges encountered in carrying out the new ATS/IDSA guideline recommendations.

Results

There were 1133 unique patients who satisfied our definition of clinically defined CAP, of whom 109 (9.6%) had a bacterial pathogen isolated. There were 24 P. aeruginosa isolates and 11 MRSA isolates in 33 patients. Thus, the prevalence P. aeruginosa and MRSA was 2.9% in the overall CAP cohort, but 30.3% in the microbiologically confirmed cohort. The most important predictors of either P. aeruginosa or MRSA isolation were tracheostomy (odds ratio [OR] 22.08; 95% confidence interval [CI] 10.39-46.96) and gastrostomy tube (OR 14.7; 95% CI 7.14-30.26). Challenges included determining the suspected infection type in patients admitted simply for "sepsis"; interpreting dictated radiology reports; determining functional status, presence of indwelling lines and tubes, and long-term care facility residence from the electronic health record; and correctly attributing culture results to pneumonia.

Conclusion

Prevalence of MRSA and P. aeruginosa was low among patients admitted in our medical system with CAP - now broadly defined - but high among those with a microbiologically confirmed bacterial etiology. Our locally derived predictors of MRSA and P. aeruginosa can be used to aid our emergency physicians in empiric antibiotic selection for CAP. Findings from this project might inform efforts at other institutions.

SERS-based rapid susceptibility testing of commonly administered antibiotics on clinically important bacteria species directly from blood culture of bacteremia patients

Bloodstream infections are a growing public health concern due to emerging pathogens and increasing antimicrobial resistance. Rapid antibiotic susceptibility testing (AST) is urgently needed for timely and optimized choice of antibiotics, but current methods require days to obtain results. Here, we present a general AST protocol based on surface-enhanced Raman scattering (SERS-AST) for bacteremia caused by eight clinically relevant Gram-positive and Gram-negative pathogens treated with seven commonly administered antibiotics. Our results show that the SERS-AST protocol achieves a high level of agreement (96% for Gram-positive and 97% for Gram-negative bacteria) with the widely deployed VITEK 2 diagnostic system. The protocol requires only five hours to complete per blood-culture sample, making it a rapid and effective alternative to conventional methods. Our findings provide a solid foundation for the SERS-AST protocol as a promising approach to optimize the choice of antibiotics for specific bacteremia patients. This novel protocol has the potential to improve patient outcomes and reduce the spread of antibiotic resistance.

Empirical Anti-MRSA vs Standard Antibiotic Therapy and Risk of 30-Day Mortality in Patients Hospitalized for Pneumonia

IMPORTANCE

Use of empirical broad-spectrum antibiotics for pneumonia has increased owing to concern for resistant organisms, including methicillin-resistant Staphylococcus aureus (MRSA). The association of empirical anti-MRSA therapy with outcomes among patients with pneumonia is unknown, even for high-risk patients.

OBJECTIVE

To compare 30-day mortality among patients hospitalized for pneumonia receiving empirical anti-MRSA therapy vs standard empirical antibiotic regimens.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective multicenter cohort study was conducted of all hospitalizations in which patients received either anti-MRSA or standard therapy for community-onset pneumonia in the Veterans Health Administration health care system from January 1, 2008, to December 31, 2013. Subgroups of patients analyzed were those with initial intensive care unit admission, MRSA risk factors, positive results of a MRSA surveillance test, and positive results of a MRSA admission culture. Primary analysis was an inverse probability of treatment-weighted propensity score analysis using generalized estimating equation regression; secondary analyses included an instrumental variable analysis. Statistical analysis was conducted from June 14 to November 20, 2019.

EXPOSURES

Empirical anti-MRSA therapy plus standard pneumonia therapy vs standard therapy alone within the first day of hospitalization.

MAIN OUTCOMES AND MEASURES

Risk of 30-day all-cause mortality after adjustment for patient comorbidities, vital signs, and laboratory results. Secondary outcomes included the development of kidney injury and secondary infections with Clostridioides difficile, vancomycin-resistant Enterococcus species, or gram-negative bacilli.

RESULTS

Among 88 605 hospitalized patients (86 851 men; median age, 70 years [interquartile range, 62-81 years]), empirical anti-MRSA therapy was administered to 33 632 (38%); 8929 patients (10%) died within 30 days. Compared with standard therapy alone, in weighted propensity score analysis, empirical anti-MRSA therapy plus standard therapy was significantly associated with an increased adjusted risk of death (adjusted risk ratio [aRR], 1.4 [95% CI, 1.3-1.5]), kidney injury (aRR, 1.4 [95% CI, 1.3-1.5]), and secondary C difficile infections (aRR, 1.6 [95% CI, 1.3-1.9]), vancomycin-resistant Enterococcus spp infections (aRR, 1.6 [95% CI, 1.0-2.3]), and secondary gram-negative rod infections (aRR, 1.5 [95% CI, 1.2-1.8]). Similar associations between anti-MRSA therapy use and 30-day mortality were found by instrumental variable analysis (aRR, 1.6 [95% CI, 1.4-1.9]) and among patients admitted to the intensive care unit (aRR, 1.3 [95% CI, 1.2-1.5]), those with a high risk for MRSA (aRR, 1.2 [95% CI, 1.1-1.4]), and those with MRSA detected on surveillance testing (aRR, 1.6 [95% CI, 1.3-1.9]). No significant favorable association was found between empirical anti-MRSA therapy and death among patients with MRSA detected on culture (aRR, 1.1 [95% CI, 0.8-1.4]).

CONCLUSIONS AND RELEVANCE

This study suggests that empirical anti-MRSA therapy was not associated with reduced mortality for any group of patients hospitalized for pneumonia. These results contribute to a growing body of evidence that questions the value of empirical use of anti-MRSA therapy using existing risk approaches.

Nursing Home-Associated Pneumonia, Part II: Etiology and Treatment

This is the second of 2 parts of a narrative review of nursing home-associated pneumonia (NHAP) that deals with etiology and treatment in the nursing home. In the 1980s and 1990s, the etiology of NHAP was considered to be similar to community-acquired pneumonia (CAP). This belief was reflected in CAP guidelines until 2005 when the designation healthcare-associated pneumonia or HCAP was introduced and nursing home residents were included in the HCAP category. Patients in the HCAP group were thought to be at high risk for pneumonia because of multidrug resistant organisms and required empiric broad-spectrum antibiotic therapy much like people with hospital-acquired infection. Subsequent studies of the etiology of NHAP using sophisticated diagnostic testing found limited evidence of resistant organisms such as methicillin-resistant Staphylococcus aureus or resistant gram-negative organisms or atypical organisms. In terms of management of NHAP in the nursing home there are several considerations that are discussed: hospitalization decision, initial oral or parenteral therapy, timing of switch to an oral regimen if parenteral therapy is initially prescribed, duration of therapy with an emphasis on shorter courses, and follow-up during therapy including the use of the "antibiotic time out" protocol. The oral and parenteral antibiotic regimens recommended for treatment of NHAP in this report are based on limited information because there are no randomized controlled trials to define the optimum regimen. In conclusion, most residents with pneumonia can be treated successfully in the nursing home. However, there is an urgent need for a specific NHAP diagnosis and treatment guideline that will give providers guidance in the management of this infection in the nursing home.

Health Care-Associated Pneumonia: Is It Still a Useful Concept?

"Health care-associated pneumonia (HCAP) was introduced into guidelines because of concerns about the increasing prevalence of drug-resistant pathogens (DRPs) not covered by standard empirical therapy. We now know that DRPs are very localized phenomena with low rates in most sites. Although HCAP risk factors are associated with a higher mortality, this is driven by comorbidities rather than the pathogens. Empirical coverage of DRPs has generally not resulted in better patient outcomes. A far more nuanced approach must be taken for patients with risk factors for DRPs taking into account the local cause and severity of disease.

Validation of the prediction rules identifying drug-resistant pathogens in community-onset pneumonia

Background

Appropriate initial antibiotic treatment and avoiding administration of unnecessary broad-spectrum antibiotics are important for the treatment of pneumonia. To achieve this, assessment of risk for drug-resistant pathogens (DRPs) at diagnosis is essential.

Purpose

The aim of this study was to validate a predictive rule for DRPs that we previously proposed (the community-acquired pneumonia drug-resistant pathogen [CAP-DRP] rule), comparing several other predictive methods.

Patients and methods

A prospective observational study was conducted in hospitalized patients with community-onset pneumonia at four institutions in Japan. Pathogens identified as not susceptible to ceftriaxone, ampicillin–sulbactam, macrolides, and respiratory fluoroquinolones were defined as CAP-DRPs.

Results

CAP-DRPs were identified in 73 (10.1%) of 721 patients analyzed. The CAP-DRP rule differentiated low vs high risk of CAP-DRP at the threshold of ≥3 points or 2 points plus any of methicillin-resistant Staphylococcus aureus specific factors with a sensitivity of 0.45, specificity of 0.87, positive predictive value of 0.47, negative predictive value of 0.87, and accuracy of 0.79. Its discrimination performance, area under the receiver operating characteristic curve, was 0.73 (95% confidence interval 0.66–0.79). Specificity of the CAP-DRP rule against CAP-DRPs was the highest among the six predictive rules tested.

Conclusion

The performance of the predictive rules and criteria for CAP-DRPs was limited. However, the CAP-DRP rule yielded high specificity and could specify patients who should be treated with non-broad-spectrum antibiotics, eg, a non-pseudomonal β-lactam plus a macrolide, more precisely.

Novel N-chloramine precursors for antimicrobial application: synthesis and facile covalent immobilization on polyurethane surface based on perfluorophenyl azide (PFPA) chemistry

To control the pathogen cross contaminations on medical material surface, there is a pressing need to develop antimicrobial materials with highly efficacious surface biocidal activity. In this work, N-chloramine precursors containing a quaternary ammonium unit and perfluorophenyl azide unit were synthesized and covalently immobilized on inert polyurethane (PU) film upon UV light irradiation. The surface modification was confirmed by contact angle, Fourier transform infrared (ATR FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) analyses. After bleaching treatment, satisfactory biocidal activity was achieved for the surface-modified PU films. It was found that the introduced surface QA center contributed an even faster surface contact killing behavior and that precursors with a longer structural linker caused higher surface chlorine content and higher antimicrobial efficacy. This approach provides a novel and facile method that enables the covalent immobilization of N-chloramine precursors on inert polymeric surface to produce durable antimicrobial materials.

Broad- versus Narrow-Spectrum Oral Antibiotic Transition and Outcomes in Health Care-associated Pneumonia

RATIONALE

Guidelines recommend a switch from intravenous to oral antibiotics once patients who are hospitalized with pneumonia achieve clinical stability. However, little evidence guides the selection of an oral antibiotic for patients with health care-associated pneumonia, especially where no microbiological diagnosis is made.

OBJECTIVES

To compare outcomes between patients who were transitioned to broad- versus narrow-spectrum oral antibiotics after initially receiving broad-spectrum intravenous antibiotic coverage.

METHODS

We performed a secondary analysis of an existing database of adults with community-onset pneumonia admitted to seven Utah hospitals. We identified 220 inpatients with microbiology-negative health care-associated pneumonia from 2010 to 2012. After excluding inpatient deaths and treatment failures, 173 patients remained in which broad-spectrum intravenous antibiotics were transitioned to an oral regimen. We classified oral regimens as broad-spectrum (fluoroquinolone) versus narrow-spectrum (usually a β-lactam). We compared demographic and clinical characteristics between groups. Using a multivariable regression model, we adjusted outcomes by severity (electronically calculated CURB-65), comorbidity (Charlson Index), time to clinical stability, and length of intravenous therapy.

MEASUREMENTS AND MAIN RESULTS

Age, severity, comorbidity, length of intravenous therapy, and clinical response were similar between the two groups. Observed 30-day readmission (11.9 vs. 21.4%; P = 0.26) and 30-day all-cause mortality (2.3 vs. 5.3%; P = 0.68) were also similar between the narrow and broad oral antibiotic groups. In multivariable analysis, we found no statistically significant differences for adjusted odds of 30-day readmission (adjusted odds ratio, 0.56; 95% confidence interval, 0.06-5.2; P = 0.61) or 30-day all-cause mortality (adjusted odds ratio, 0.55; 95% confidence interval, 0.19-1.6; P = 0.26) between narrow and broad oral antibiotic groups.

CONCLUSIONS

On the basis of analysis of a limited number of patients observed retrospectively, our findings suggest that it may be safe to switch from broad-spectrum intravenous antibiotic coverage to a narrow-spectrum oral antibiotic once clinical stability is achieved for hospitalized patients with health care-associated pneumonia when no microbiological diagnosis is made. A larger retrospective study with propensity matching or regression-adjusted test of equivalence or ideally a prospective comparative effectiveness study will be necessary to confirm our observations.

Mortality in patients with community-onset pneumonia at low risk of drug-resistant pathogens: Impact of β-lactam plus macrolide combination therapy

BACKGROUND AND OBJECTIVE

Drug-resistant pathogen (DRP) risk stratification is important for choosing a treatment strategy for community-onset pneumonia. Evidence for benefits of non-antipseudomonal β-lactam plus macrolide combination therapy (BLM) on mortality is limited in patients at low DRP risk. Risk factors for mortality remain to be clarified.

METHODS

Post hoc analysis using a prospective multicentre study cohort of community-onset pneumonia was performed to assess 30-day differences in mortality between non-antipseudomonal β-lactam monotherapy (BL) and BLM groups. Logistic regression analysis was performed to assess the therapeutic effect and risk factors for mortality in patients at low DRP risk.

RESULTS

In total, 594 patients with community-onset pneumonia at low DRP risk (369 BL and 225 BLM) were analysed. The 30-day mortality in BL and BLM was 13.8% and 1.8%, respectively (P < 0.001). Multivariate analysis showed that BLM reduced the 30-day mortality (adjusted odds ratio: 0.28, 95% CI: 0.09-0.87) compared with BL. Independent prognostic factors for 30-day mortality included arterial partial pressure of carbon dioxide (PaCO₂ ) > 50 mm Hg, white blood cell count < 4000/mm³ , non-ambulatory status, albumin < 3.0 g/dL, haematocrit < 30%, age ≥ 80 years, respiratory rate > 25/min and body temperature < 36°C.

CONCLUSION

In patients with community-onset pneumonia at low DRP risk, BLM treatment reduced 30-day mortality compared with BL. Independent risk factors for mortality are potential confounding factors when assessing antibiotic effects in randomized clinical trials.

Risk factors for multidrug-resistant pathogens in bronchiectasis exacerbations

BACKGROUND

Non-cystic fibrosis bronchiectasis is a chronic structural lung condition that courses with recurrent infectious exacerbations that lead to frequent antibiotic treatment making this population more susceptible to acquire pathogens with antibiotic resistance. We aimed to investigate risk factors associated with isolation of multidrug-resistant pathogens in bronchiectasis exacerbations.

METHODS

A prospective observational study was conducted in two tertiary-care hospitals, enrolling patients when first exacerbation appeared. Multidrug-resistance was determined according to European Centre of Diseases Prevention and Control classification.

RESULTS

Two hundred thirty three exacerbations were included and microorganisms were isolated in 159 episodes. Multidrug-resistant pathogens were found in 20.1% episodes: Pseudomonas aeruginosa (48.5%), methicillin-resistant Staphylococcus aureus (18.2%) and Extended spectrum betalactamase + Enterobacteriaceae (6.1%), and they were more frequent in exacerbations requiring hospitalization (24.5% vs. 10.2%, p: 0.016). Three independent multidrug-resistant risk factors were found: chronic renal disease (Odds ratio (OR), 7.60, 95% CI 1.92-30.09), hospitalization in the previous year (OR, 3.88 95% CI 1.37-11.02) and prior multidrug-resistant isolation (OR, 5.58, 95% CI 2.02-15.46). The proportion of multidrug-resistant in the 233 exacerbations was as follows: 3.9% in patients without risk factors, 12.6% in those with 1 factor and 53.6% if ≥2 risk factors.

CONCLUSIONS

Hospitalization in the previous year, chronic renal disease, and prior multidrug-resistant isolation are risk factors for identification multidrug-resistant pathogens in exacerbations. This information may assist clinicians in choosing empirical antibiotics in daily clinical practice.

Regional differences in antibiotic-resistant pathogens in patients with pneumonia: Implications for clinicians

Antibiotic resistance is of great concern for both infection control and the treatment of infectious diseases. Previous studies reported that the occurrence of drug-resistant pathogens (DRPs)-for instance, methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa and extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae-were associated with inappropriate antibiotic treatment that resulted in adverse outcomes. In addition, unnecessary use of broad-spectrum antibiotics for patients with non-DRPs increased mortality. Therefore, the assessment of risk for DRPs at diagnosis is critical to avoid patients' adverse events. In the present review, we discuss regional differences in the prevalence of DRPs, which ranged from 6% to 45%, in patients with community-onset pneumonia, including both community-acquired and healthcare-associated pneumonia. We then introduce the reported risk factors for DRPs in those patients, and present proposed prediction models for identifying patients with DRPs at diagnosis. Physicians should be aware that some of the risk factors for DRPs (e.g. prior antibiotic use and prior hospitalization) were common between regions; however, others may be different or the weighting of the risks may vary, even for the same risk factors. Therefore, a specific evaluation of risk factors for DRPs is recommended for each region and institution. Furthermore, we present a possible strategy for initial antibiotic selection in patients with community-onset pneumonia, considering DRPs risk. We also discuss future directions for the study of DRPs in community-onset, hospital-acquired and ventilator-associated pneumonia to improve the management of patients with pneumonia.