Risk factors of methicillin-resistant Staphylococcus aureus bacteremic pneumonia in the emergency department

The infection rate of methicillin-resistant Staphylococcus aureus (MRSA) has increased worldwide and MRSA bacteremic pneumonia is associated with a high mortality rate. This is a retrospective study conducted at a university hospital in Korea involving adult patients diagnosed as bacteremic pneumonia caused by S. aureus in the ED between January 2009 and December 2019. We compared MRSA bacteremic pneumonia patients (n = 56) to methicillin-susceptible S. aureus bacteremic pneumonia patients (n = 49). Our study showed that that underlying hypertension (OR = 5.68; 95% CI = 2.00–16.11; p = 0.001) and cerebrovascular disease (OR = 3.54; 95% CI = 1.06–11.75; p = 0.038), recent intravenous therapy within 1 month (OR = 8.38; 95% CI = 2.88–24.38; p = 0.0001), and pleural effusion on chest radiography (OR = 5.77; 95% CI = 1.79–18.57; p = 0.003) were independent risk factors for MRSA bacteremic pneumonia presenting to the ED. Although MRSA infection has been more frequently derived from the community than before, inappropriate empiric antibiotic treatment was overwhelmingly observed in the majority of patients in our study. Considering the resistance of MRSA to the typical empiric regimen prescribed for community-acquired pneumonia, emergency physicians should pay attention to the predictors for MRSA bacteremic pneumonia including pleural effusion on chest radiography when deciding on the appropriate empiric antimicrobial therapy for pneumonia patients in the ED.

Draft Genome Sequence of Methicillin-Resistant Staphylococcus aureus Harboring Staphylococcal Cassette Chromosome mec Type IX, Isolated from a Fatal Bacteremic Pneumonia Case

Here, we report the whole-genome sequence of a methicillin-resistant Staphylococcus aureus strain harboring staphylococcal cassette chromosome mec (SCC mec ) type IX, isolated from a fatal sepsis case. Genomic analysis revealed that the isolate was sequence type 9 and spa type t3446, carrying multiple antimicrobial-resistant genes comprising mecA , blaZ , aac(6′)-aph(2″) , aadD , ant(6)-Ia , lsa (E), dfrG , tet (M), fexA , and lnu (B).

295. Is Herd Immunity from Pneumococcal Conjugate Vaccines Changing the Clinical Features of Invasive Pneumococcal Disease in Adults?

Background Numerous factors that affect the presentation and severity of pneumococcal disease. Several studies in the pre-PCV era demonstrated that organism characteristics, including serotype, are associated with variability in disease presentation and severity. We undertook an analysis of population based surveillance for invasive pneumococcal disease (IPD) to assess whether herd immunity from PCVs will change the presentation and severity of IPD in adults Methods TIBDN has performed population-based surveillance for IPD in Toronto and Peel region (pop’n 4.5M) since 1995. All sterile site isolates of S. pneumoniae are reported to a central study laboratory, isolates are serotyped, and clinical and vaccination data are collected via patient and physician interview and chart review. Population data are obtained from Statistics Canada. Backwards stepwise logistic regression assessed patient characteristics, illness features, and isolate factors associated with clinical presentation and case fatality. Results Between 1995 and 2018, 8815 episodes of IPD were identified in adults. Patients infected with PCV10not7 serotypes were younger, more likely male and without underlying illness. Patients with infections due to non-vaccine types were more likely to be immunocompromised. Case fatality in IPD declined from 177/754 in 1995/6 to 113/554 in 2017/8; OR 0.67, 95%CI0.51-0.86, P< .0001) and in all serotype groups (Figure). In multivariable models adjusted for host factors, relative to infections caused PCV7 serotypes, those caused by PCV10not7 were less likely to be fatal (OR 0.65, 95%CI 0.46–0.91); those caused by PCV13not10 were more likely to be fatal (OR 1.6, 95%CI 1.3–1.9). Bacteremic pneumonia as a proportion of presentations is highest in IPD due to PCV10not7 and PCV13not10 serotypes (85% and 83%, respectively), and lowest in IPD due to non-vaccine serotypes and PCV20not15 (59% and 68%, P< .0001). Meningitis is least common in IPD due to PCV10not7 serotypes (2.6%), and highest in cases due to non-vaccine types and PCV20not15 (9.0% and 8.0%, respectively, P< .0001). FIgure Conclusion In our population, herd immunity from PCVs will result in a higher proportion of adult IPD occurring in immunocompromised cases, and a shift from bacteremic pneumonia to bacteremia without focus and meningitis. Disclosures Allison McGeer, MD, FRCPC, GlaxoSmithKline (Advisor or Review Panel member, Research Grant or Support)Merck (Advisor or Review Panel member, Research Grant or Support)Pfizer (Research Grant or Support)

1404. Twenty-year impact of Pneumococcal Conjugate Vaccines (PCV) on the burden of invasive pneumococcal disease in US children less than 5 years of age

Background Clinical trials of PCV7 demonstrate significant reductions in vaccine-type (VT) invasive pneumococcal disease (IPD), clinically diagnosed pneumonia in children less than 5 years of age and VT acute otitis media in children < 2 years of age. Observational, population-based studies demonstrate a reduction in overall IPD in US children following the introduction of PCV7 and PCV13. The cumulative impact of PCV on IPD syndromes over the 20 years following introduction into the US national immunization program has not been detailed. Methods Published and unpublished data from the Active Bacterial Core (ABC) surveillance network were used to calculate annual incidence rates of IPD and the proportional distribution by syndrome in children < 5 years of age. Cases averted were calculated from published incidence for each IPD syndrome and population data, for the pre-PCV, PCV7, and PCV13 eras. Cases averted over 2000-2009 were assumed due to PCV7 only, and those averted from 2010-2019 were assumed due to PCV13 only. It was assumed that in the absence of PCVs, disease incidence would have remained constant. Results Annual cases of overall IPD, pneumococcal meningitis, and bacteremic pneumonia each declined more than 85% between the pre PCV7 incidence and the estimated incidence for 2019 (table 1). Overall, we estimated 282,600 cases of IPD, including 30,500 cases of meningitis and 78,400 cases of bacteremic pneumonia were averted. We calculated a reduction of ~ 287,600 VT cases of IPD minimally offset by an increase of ~5,000 non-VT cases. Deaths per 100,000 children < 5 years of age attributable to IPD declined by 67% in 2009 and by 64% in 2019 compared to 1997-1999. In total, 1,628 deaths in children < 5 years were averted between 2000 and 2019. Table 1. Annual Cases of IPD by syndrome in US Children Less than 5 years of age Conclusion The substantial public health impact of PCVs over the last two decades, as measured in cases and deaths averted in children less than 5 years, re-enforces the important role vaccines play in reducing the burden of serious disease in children. Disclosures Rotem Lapidot, MD, MSCI, Pfizer (Consultant) Ruth Chapman, MSc, PhD, Evidera, Inc, (Evidera, Inc. received the funding to conduct this study.) (Consultant) Kelly Sutton, PhD, Evidera (Employee) Desmond Dillon-Murphy, MSc, PhD, Evidera, Inc. (Evidera, Inc. received the funding to conduct this study.) (Consultant) Shreeya Patel, PhD, Evidera, Inc, (Evidera, Inc. received the funding to conduct this study.) (Consultant) Erica Chilson, PharmD, Pfizer (Employee, Shareholder) Vincenza Snow, MD, Pfizer (Employee) Raymond Farkouh, PhD, Pfizer (Employee) Matthew Wasserman, MSc., Pfizer Inc. (Employee) Stephen I. Pelton, MD, Merck vaccine (Consultant, Grant/Research Support)Pfizer (Consultant, Grant/Research Support)Sanofi Pasteur (Consultant, Other Financial or Material Support, DSMB)Seqirus Vaccine Ltd. (Consultant)

Influence of severity of infection on the effect of appropriate antimicrobial therapy for Acinetobacter baumannii bacteremic pneumonia

Background The impact of appropriate antimicrobial therapy for A. baumannii bacteremic pneumonia has not been well established due to the inclusion of the three phenotypically indistinguishable Acinetobacter species and confounding factors including underlying diseases and severity of infection. This retrospective study aimed to evaluate the impact of appropriate antimicrobial therapy on 14-day mortality in A. baumannii bacteremic pneumonia patients after adjusting for risk factors. Methods This study was conducted at five medical centers in Taiwan between July 2012 and June 2016. A. baumannii species identification was performed using reference molecular methods. Risk factors for 14-day mortality were analyzed via logistic regression. The interaction between the Acute Physiology and Chronic Health Evaluation (APACHE) II score and appropriate antimicrobial therapy was assessed using the logistic model. Results A total of 336 patients with monomicrobial A. baumannii bacteremic pneumonia were included in this study. The overall 14-day mortality rate was 47.3%. The crude mortality of appropriate antimicrobial therapy was 35.9% (57 of 151 patients). Appropriate antimicrobial therapy was associated with a lower mortality after multivariate adjustment (odds ratio [OR], 0.57; 95% confidence interval [CI], 0.34–0.97; p = 0.04), and the effect was influenced by APACHE II score (OR for interaction term, 0.0098; 95% CI, 0.0005–0.1885; p = 0.002). Further analysis demonstrated that appropriate antimicrobial therapy significantly reduced 14-day mortality among the patients with an APACHE II score > 35 (OR 0.0098; 95% CI 0.0005–0.1885). Conclusion Appropriate antimicrobial therapy decreases 14-day mortality of the most severely ill patients with A. baumannii bacteremic pneumonia.

Influence of Severity of Infection on the Effect of Appropriate Antimicrobial Therapy for Acinetobacter baumannii Bacteremic Pneumonia

Background The impact of appropriate antimicrobial therapy for A. baumannii bacteremic pneumonia has not been well established due to the inclusion of the three phenotypically indistinguishable Acinetobacter species and confounding factors including underlying diseases and severity of infection. This retrospective study aimed to evaluate the impact of appropriate antimicrobial therapy on 14-day mortality in A. baumannii bacteremic pneumonia patients after adjusting for risk factors. Methods This study was conducted at five medical centers in Taiwan between July 2012 and June 2016. A. baumannii species identification was performed using reference molecular methods. Risk factors for 14-day mortality were analyzed via logistic regression. The interaction between the Acute Physiology and Chronic Health Evaluation (APACHE) II score and appropriate antimicrobial therapy was assessed using the logistic model. Results A total of 336 patients with monomicrobial A. baumannii bacteremic pneumonia were included in this study. The overall 14-day mortality rate was 47.3%. The crude mortality of appropriate antimicrobial therapy was 35.9% (57 of 151 patients). Appropriate antimicrobial therapy was associated with a lower mortality after multivariate adjustment (odds ratio [OR], 0.57; 95% confidence interval [CI], 0.34-0.97; p = 0.04), and the effect was influenced by APACHE II score (OR for interaction term, 0.0098; 95% CI, 0.0005-0.1885; p = 0.002). Further analysis demonstrated that appropriate antimicrobial therapy significantly reduced 14-day mortality among the patients with an APACHE II score >35 (OR 0.0098; 95% CI 0.0005-0.1885). Conclusion Appropriate antimicrobial therapy decreases 14-day mortality of the most severely ill patients with A. baumannii bacteremic pneumonia.

Clinical Characteristics and Adverse Clinical Outcomes of Invasive Haemophilus influenzae Serotype a Cases—United States, 2011–2015

Background Incidence of invasive disease due to Haemophilus influenzae serotype a (Hia) increased an average of 13% annually from 2002 through 2015. We describe clinical characteristics and adverse clinical outcomes of US invasive Hia cases detected through multistate surveillance during 2011–2015. Methods Medical record data were abstracted for cases reported in 8 jurisdictions conducting active population- and laboratory-based surveillance for invasive Hia disease across the United States. Isolates from sterile sites were serotyped using real-time polymerase chain reaction. Adverse clinical outcomes were defined as any possible complication of meningitis, bacteremic pneumonia, or bacteremia (including hearing loss and developmental delay, but excluding death) and were assessed at hospital discharge and one-year post-disease onset. Results During 2011–2015, 190 Hia cases were reported to the 8 participating sites; 169 (88.9%) had data abstracted. Many patients were aged <5 years (42.6%). Meningitis was the most common clinical presentation among those aged <1 year (71.4%); bacteremic pneumonia was the most common presentation among persons aged ≥50 years (78.7%). Overall, 95.9% of patients were hospitalized. Among those hospitalized, 47.5% were admitted to an intensive care unit and 6.2% died during hospitalization. At hospital discharge and one-year post-disease onset, adverse outcomes were identified in 17.7% and 17.8% of patients overall and in 43.9% and 48.5% of patients with meningitis (primarily children). Conclusions Hia infection can cause severe disease that requires hospitalization and may also cause short- and long-term adverse clinical outcomes, especially among children. Novel vaccines could prevent morbidity and mortality.

Influence of Severity of Infection on the Effect of Appropriate Antimicrobial Therapy for Acinetobacter baumannii Bacteremic Pneumonia

BackgroundThe impact of appropriate antimicrobial therapy for A. baumannii bacteremic pneumonia has not been well established due to the inclusion of the three phenotypically indistinguishable Acinetobacter species and confounding factors including underlying diseases and severity of infection. This retrospective study aimed to evaluate the impact of appropriate antimicrobial therapy on 14-day mortality in A. baumannii bacteremic pneumonia patients after adjusting for risk factors. MethodsThis study was conducted at five medical centers in Taiwan between July 2012 and June 2016. A. baumannii species identification was performed using reference molecular methods. Risk factors for 14-day mortality were analyzed via logistic regression. The interaction between the Acute Physiology and Chronic Health Evaluation (APACHE) II score and appropriate antimicrobial therapy was assessed using the logistic model. ResultsA total of 336 patients with monomicrobial A. baumannii bacteremic pneumonia were included in this study. The overall 14-day mortality rate was 47.3%. The crude mortality of appropriate antimicrobial therapy was 35.9% (57 of 151 patients). Appropriate antimicrobial therapy was associated with a lower mortality after multivariate adjustment (odds ratio [OR], 0.57; 95% confidence interval [CI], 0.34-0.97; p = 0.04), and the effect was influenced by APACHE II score (OR for interaction term, 0.0098; 95% CI, 0.0005-0.1885; p = 0.002). Further analysis demonstrated that appropriate antimicrobial therapy significantly reduced 14-day mortality among the patients with an APACHE II score >35 (OR 0.0098; 95% CI 0.0005-0.1885). ConclusionAppropriate antimicrobial therapy decreases 14-day mortality of the most severely ill patients with A. baumannii bacteremic pneumonia.