Abstract
There is consensus that definitive therapy for infections with H. influenzae should include antimicrobial agents with clinical breakpoints against the bacterium. In Scandinavia, benzylpenicillin is the recommended empirical treatment for community-acquired pneumonia (CAP) except in very severe cases. However, the effect of benzylpenicillin on H. influenzae infections has been debated. The aim of this study was to compare the outcomes of patients given benzylpenicillin with patients given wide-spectrum beta-lactams (WSBL) as empirical treatment of lower respiratory tract H. influenzae infections requiring hospital care. We identified 481 adults hospitalized with lower respiratory tract infection by H. influenzae, bacteremic and non-bacteremic. Overall, 30-day mortality was 9% (42/481). Thirty-day mortality, 30-day readmission rates, and early clinical response rates were compared in patients receiving benzylpenicillin (n = 199) and a WSBL (n = 213) as empirical monotherapy. After adjusting for potential confounders, empirical benzylpenicillin treatment was not associated with higher 30-day mortality neither in a multivariate logistic regression (aOR 2.03 for WSBL compared to benzylpenicillin, 95% CI 0.91–4.50, p = 0.082), nor in a propensity score-matched analysis (aOR 2.14, 95% CI 0.93–4.92, p = 0.075). Readmission rates did not significantly differ between the study groups, but early clinical response rates were significantly higher in the WSBL group (aOR 2.28, 95% CI 1.21–4.31, p = 0.011), albeit still high in both groups (84 vs 81%). In conclusion, despite early clinical response rates being slightly lower for benzylpenicillin compared to WSBL, we found no support for increased mortality or readmission rates in patients empirically treated with benzylpenicillin for lower respiratory tract infections by H. influenzae.
Highlights
Haemophilus influenzae is considered the second most common bacterial cause of community-acquired pneumonia (CAP) after Streptococcus pneumoniae [1]
The all-cause 30-day mortality of severe lower respiratory tract infections caused by H. influenzae was 9%
In an analysis adjusted for potential confounders, empirical monotherapy with benzylpenicillin was not significantly associated with increased risk of mortality or readmission
Summary
Haemophilus influenzae is considered the second most common bacterial cause of community-acquired pneumonia (CAP) after Streptococcus pneumoniae [1]. Surveillance data have suggested an increased incidence of invasive infections with H. influenzae in recent years, and since the introduction of capsule type b polysaccharide conjugate vaccines, nonencapsulated strains (NTHi) dominate, followed by capsule type f [2,3,4]. This has led to a shift in the clinical epidemiology of severe H. influenzae infections, as most cases present as pneumonia in older adults or patients with comorbidities, most notably chronic obstructive pulmonary disease (COPD) [2, 3, 5]. This has yet to be confirmed, one recent study from Great Britain using molecular diagnostics showed it to be the most common agent in CAP, contributing to 40% of cases [7].
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