Revisiting Combination Antibiotic Therapy for Community-Acquired Invasive Streptococcus pneumoniae Pneumonia

The dilemma of monotherapy or combination therapy in community-acquired pneumonia

SCOPE

To study the factors associated with mortality in hospitalized patients with community-acquired pneumonia treated with monotherapy or combination therapy.

METHODS

PubMed and Scopus were searched. Patients receiving macrolides, β-lactams and fluoroquinolones, as monotherapy or in combination, were included. Meta-analyses and meta-regressions were performed.

RESULTS

Fifty studies were included. Overall, monotherapy was not associated with higher mortality than combination (RR 1.14, 95% CI 0.99-1.32, I² 84%). Monotherapy was associated with higher mortality than combination in North American and retrospective studies. β-lactam monotherapy was associated with higher mortality than β-lactam/macrolide combination in the primary (1.32, 1.12-1.56, I² 85%) and most sensitivity analyses. There was no difference in mortality between fluoroquinolone monotherapy and β-lactam/macrolide combination (0.98, 0.78-1.23, I² 73%). In meta-regressions, the moderators that could partially explain the observed statistical heterogeneity were the frequency of cancer patients (P = .03) and Pneumonia Severity Index score IV (P = .008).

CONCLUSION

Due to the considerable heterogeneity and inclusion of unadjusted data, it is difficult to recommend a specific antibiotic regimen over another. Specific antibiotic regimens, study design and the characteristics of the population under study seem to influence the reported outcomes.

Mechanisms of action and in vivo antibacterial efficacy assessment of five novel hybrid peptides derived from Indolicidin and Ranalexin against Streptococcus pneumoniae

BACKGROUND

Antimicrobial peptides (AMPs) are of great potential as novel antibiotics for the treatment of broad spectrum of pathogenic microorganisms including resistant bacteria. In this study, the mechanisms of action and the therapeutic efficacy of the hybrid peptides were examined.

METHODS

TEM, SEM and ATP efflux assay were used to evaluate the effect of hybrid peptides on the integrity of the pneumococcal cell wall/membrane. DNA retardation assay was assessed to measure the impact of hybrid peptides on the migration of genomic DNA through the agarose gel. In vitro synergistic effect was checked using the chequerboard assay. ICR male mice were used to evaluate the in vivo toxicity and antibacterial activity of the hybrid peptides in a standalone form and in combination with ceftriaxone.

RESULTS

The results obtained from TEM and SEM indicated that the hybrid peptides caused significant morphological alterations in Streptococcus pneumoniae and disrupting the integrity of the cell wall/membrane. The rapid release of ATP from pneumococcal cells after one hour of incubation proposing that the antibacterial action for the hybrid peptides is based on membrane permeabilization and damage. The DNA retardation assay revealed that at 62.5 µg/ml all the hybrid peptides were capable of binding and preventing the pneumococcal genomic DNA from migrating through the agarose gel. In vitro synergy was observed when pneumococcal cells treated with combinations of hybrid peptides with each other and with conventional drugs erythromycin and ceftriaxone. The in vivo therapeutic efficacy results revealed that the hybrid peptide RN7-IN8 at 20 mg/kg could improve the survival rate of pneumococcal bacteremia infected mice, as 50% of the infected mice survived up to seven days post-infection. In vivo antibacterial efficacy of the hybrid peptide RN7-IN8 was signficantly improved when combined with the standard antibiotic ceftriaxone at (20 mg/kg + 20 mg/kg) as 100% of the infected mice survived up to seven days post-infection.

DISCUSSION

Our results suggest that attacking and breaching the cell wall/membrane is most probably the principal mechanism for the hybrid peptides. In addition, the hybrid peptides could possess another mechanism of action by inhibiting intracellular functions such as DNA synthesis. AMPs could play a great role in combating antibiotic resistance as they can reduce the therapeutic concentrations of standard drugs.

Using cluster analysis of cytokines to identify patterns of inflammation in hospitalized patients with community-acquired pneumonia: a pilot study

INTRODUCTION

Patients with severe community-acquired pneumonia (CAP) are believed to have an exaggerated inflammatory response to bacterial infection. Therapies aiming to modulate the inflammatory response have been largely unsuccessful, perhaps reflecting that CAP is a heterogeneous disorder that cannot be modulated by a single anti-inflammatory approach. We hypothesize that the host inflammatory response to pneumonia may be characterized by distinct cytokine patterns, which can be harnessed for personalized therapies.

METHODS

Here, we use hierarchical cluster analysis of cytokines to examine if patterns of inflammatory response in 13 hospitalized patients with CAP can be defined. This was a secondary data analysis of the Community-Acquired Pneumonia Inflammatory Study Group (CAPISG) database. The following cytokines were measured in plasma and sputum on the day of admission: interleukin (IL)-1β, IL-1 receptor antagonist (IL-1ra), IL-6, CXCL8 (IL-8), IL-10, IL-12p40, IL-17, interferon (IFN)γ, tumor necrosis factor (TNF)α, and CXCL10 (IP-10). Hierarchical agglomerative clustering algorithms were used to evaluate clusters of patients within plasma and sputum cytokine determinations.

RESULTS

A total of thirteen patients were included in this pilot study. Cluster analysis identified distinct inflammatory response patterns of cytokines in the plasma, sputum, and the ratio of plasma to sputum.

CONCLUSIONS

Inflammatory response patterns in plasma and sputum can be identified in hospitalized patients with CAP. Characterization of the local and systemic inflammatory response may help to better discriminate patients for enrollment into clinical trials of immunomodulatory therapies.

Three Decades of Follow-up of Adults After Recovery From Invasive Pneumococcal Pneumonia

BACKGROUND

Streptococcus pneumoniae infection is the most common cause of community-acquired pneumonia in adults. Invasive pneumococcal disease (IPD) carries a high case fatality rate. We investigated the lifespan of adults who recovered from IPD during a 32-year follow-up.

MATERIALS AND METHODS

We determined whether adults discharged after an episode of IPD from hospitals affiliated with the Marshall University Joan C. Edwards School of Medicine in Huntington, West Virginia from 1983-2003 were alive on June 30, 2014. Lifespan was assessed by Kaplan-Meier methodology, Cox proportional hazards multivariate analysis, life expectancy using life tables for West Virginia, years of potential life lost and serotype occurrence.

RESULTS

The study group comprised 155 adults who survived IPD. They had a mean age at discharge of 64.6 years, mean lifespan after IPD of 7.1 years, mean expected lifespan after IPD of 17.0 years, mean age at death of 71.6 years and a mean life expectancy of 81.6 years. Only 14 (9.0%) patients lived longer than their life expectancy. Of the 13 comorbid diseases analyzed, cancer and neurologic diseases and the number of comorbid diseases suffered by each patient were the significant variables associated with survival. The mean years of potential life lost was 9.936 years. Only serotype 12 of 31 serotypes recovered occurred more often in patients who survived for 11 or more years after discharge (relative risk = 3.44, 95% CI: 1.19-9.95).

CONCLUSIONS

The fact that most adult patients who recovered from IPD died before their documented life expectancy argues for the pernicious severity of IPD and the importance of immunization of adults with pneumococcal vaccines.

Using cluster analysis of cytokines to identify patterns of inflammation in hospitalized patients with community-acquired pneumonia: a pilot study

INTRODUCTION

Patients with severe community-acquired pneumonia (CAP) are believed to have an exaggerated inflammatory response to bacterial infection. Therapies aiming to modulate the inflammatory response have been largely unsuccessful, perhaps reflecting that CAP is a heterogeneous disorder that cannot be modulated by a single anti-inflammatory approach. We hypothesize that the host inflammatory response to pneumonia may be characterized by distinct cytokine patterns, which can be harnessed for personalized therapies.

METHODS

Here, we use hierarchical cluster analysis of cytokines to examine if patterns of inflammatory response in 13 hospitalized patients with CAP can be defined. This was a secondary data analysis of the Community-Acquired Pneumonia Inflammatory Study Group (CAPISG) database. The following cytokines were measured in plasma and sputum on the day of admission: interleukin (IL)-1β, IL-1 receptor antagonist (IL-1ra), IL-6, CXCL8 (IL-8), IL-10, IL-12p40, IL-17, interferon (IFN)γ, tumor necrosis factor (TNF)α, and CXCL10 (IP-10). Hierarchical agglomerative clustering algorithms were used to evaluate clusters of patients within plasma and sputum cytokine determinations.

RESULTS

A total of thirteen patients were included in this pilot study. Cluster analysis identified distinct inflammatory response patterns of cytokines in the plasma, sputum, and the ratio of plasma to sputum.

CONCLUSIONS

Inflammatory response patterns in plasma and sputum can be identified in hospitalized patients with CAP. Characterization of the local and systemic inflammatory response may help to better discriminate patients for enrollment into clinical trials of immunomodulatory therapies.

Lung inflammatory pattern and antibiotic treatment in pneumonia

BACKGROUND

In community-acquired pneumonia host inflammatory response against the causative microorganism is necessary for infection resolution. However an excessive response can have deleterious effects. In addition to antimicrobial effects, macrolide antibiotics are known to possess immunomodulatory properties.

METHODS

A prospective study was performed on 52 admitted patients who developed an inadequate response after 72 hours of antibiotic treatment - non-responders community-acquired pneumonia - (blood and bronchoalveolar lavage), and two control groups: 1) community-acquired pneumonia control (blood) and 2) non-infection control (blood and bronchoalveolar lavage). Cytokine profiles (interleukin (IL)-6, IL-8, IL-10), tumour necrosis factor α and clinical outcomes were assessed.

RESULTS

Non-responders patients treated with macrolide containing regimens showed significantly lower levels of IL-6 and TNF-α in bronchoalveolar lavage fluid and lower IL-8 and IL-10 in blood than those patients treated with non-macrolide regimens. Clinical outcomes showed that patients treated with macrolide regimens required fewer days to reach clinical stability (p < 0.01) and shorter hospitalization periods (p < 0.01).

CONCLUSIONS

After 72 hours of antibiotic effect, patients who received macrolide containing regimens exhibited lower inflammatory cytokine levels in pulmonary and systemic compartments along with faster stabilization of infectious parameters.

Effect of linezolid on clinical severity and pulmonary cytokines in a murine model of influenza A and Staphylococcus aureus coinfection

Excessive inflammation contributes to the severity of post influenza pneumonia caused by methicillin resistant S.aureus (MRSA). Linezolid, vancomycin, and clindamycin are antibiotics used for MRSA infections. Linezolid has immunomodulatory properties. We report on the effects of the three antibiotics on microbial clearance, pulmonary cytokines and clinical course in a murine model of influenza and MRSA coinfection.

METHODS

B6 mice were infected with influenza A virus and 3 days later with MRSA, both intranasally. Treatment with placebo, linezolid, vancomycin or clindamycin started immediately after MRSA infection and continued for 72 hours. Bacterial and viral titers as well as cytokine concentrations in the lungs were assessed 4 and 24 hours after MRSA coinfection. Mice were weighted daily for 13 days.

RESULTS

Coinfected mice had increased pulmonary IL-1β, TNF-α and mKC at 4 and 24 hours, IL-6, IL-10 and IL-12 at 4 hours and IFN-γ at 24 hours after MRSA coinfection (all P<0.05). Compared to placebo, coinfected mice treated with linezolid, vancomycin or clindamycin had decreased pulmonary IL-6 and mKC at 4 hours and IFN-γ at 24 hours after MRSA coinfection (all P<0.05). IL-1β, TNF-α and IL-12 were similar in antibiotic-treated and placebo groups. All antibiotics similarly reduced MRSA without effect on influenza titers. Linezolid-treated mice had less weight loss on days 4-6 after influenza infection compared to placebo (all P<0.05). On all other days weight change was similar among all groups.

CONCLUSIONS

This is the first report comparing the effects of antibiotics on cytokines and clinical outcome in a murine model of influenza and MRSA coinfection. Compared to placebo, antibiotic treatment reduced maximum concentration of IL-6, mKC and IFN-γ in the lungs without any difference among antibiotics. During treatment, only linezolid delayed weight loss compared to placebo.

Treatment with anti-inflammatory drugs in community-acquired pneumonia

Pneumonia exhibits a broad range of severity, from mildly symptomatic at one end to fulminant septic shock and death at the other. Although an adequate inflammatory response is necessary for the clearance of microorganisms, excessive inflammation can lead to ongoing local and systemic damage. Because of this extended inflammatory response despite appropriate antibiotic therapy, as well as increasing antibiotic resistance, adjuvant therapy for pneumonia that can favourably modify the immune response has become an increasingly relevant approach to improve prognosis. Different adjuvant treatment options for pneumonia have recently been proposed. Promising treatment options include corticosteroids, statins, macrolides and Toll-like receptor antagonists. The aim of this review is to summarize the inflammatory response during pneumonia and discuss the current knowledge and future perspectives regarding the anti-inflammatory treatment options for patients with pneumonia.

Clinical features of patients with recurrent invasive Streptococcus pneumoniae disease

INTRODUCTION

Invasive Streptococcus pneumoniae (pneumococcal) disease (IPD) carries a high risk of death, approximately 15% to 20% in pneumonia, 40% in meningitis and 10% to 15% in septicemia. The occurrence of 2 or more IPD (recurrent) in the same individual is uncommon. The authors investigated the clinical features of patients with recurrent IPD to assess whether they possessed risk factors that increased their likelihood of recurrent IPD.

METHODS

Between 1983 and 2010, the authors identified 27 patients with recurrent IPD during inpatient surveillance of 889 patients with IPD in Huntington, WV, by recovery of pneumococci from otherwise sterile sites. Serotype/serogroup (ST/SG) was determined by capsular swelling and the penicillin MIC by E-strip. Clinical data were abstracted from hospital charts.

RESULTS

Sixteen (59%) of 27 patients were 65 years and older at first IPD, males predominated (67%), two-thirds had pneumonia and 21 (78%) had the same clinical diagnosis at both IPD. Four (80%) of 5 patients with the same ST experienced their second IPD 1 to 6 months apart, unlike most patients with discordant ST/SGs (P = 0.047). Eighty-four percent of ST/SGs were included in the 23-valent pneumococcal vaccine and occurred as often during the first and second IPD. Twenty (77%) of 26 adults suffered from comorbid diseases placing them at high risk of IPD, including multiple myeloma, HIV/AIDS, neoplasia of hematological origin and sickle cell disease.

CONCLUSIONS

Recurrent IPD occurred uncommonly. Comorbid conditions including multiple myeloma and immunosuppressive/immunodeficient conditions, chronic alcoholism and splenectomy represented unique risk factors for recurrent IPD but did not predict recurrences.

Epidemiology, microbiology, and treatment considerations for bacterial pneumonia complicating influenza

Post-influenza bacterial pneumonia is a major cause of morbidity and mortality associated with both seasonal and pandemic influenza virus illness. However, despite much interest in influenza and its complications in recent years, good clinical trial data to inform clinicians in their assessment of treatment options are scant. This paucity of evidence needs to be addressed urgently in order to improve guidance on the management of post-influenza bacterial pneumonia. The objectives of the current article are to evaluate the emergence of the 2009 H1N1 influenza pandemic and use this information as background for an in-depth review of the epidemiology of bacterial pneumonia complicating influenza, to review the bacterial pathogens most likely to be associated with post-influenza bacterial pneumonia, and to discuss treatment considerations in these patients. When determining optimal management approaches, both antiviral and antibacterial agents should be considered, and their selection should be based upon a clear understanding of how their mechanisms of action intervene in the pathogenesis of post-influenza acute bacterial pneumonia.

New modalities in treating pneumococcal pneumonia

Despite the availability of effective antibiotics and intensive medical care, pneumococcal pneumonia is still associated with substantial mortality. Early diagnosis is becoming increasingly possible. This article reviews several adjunctive measures that might be instituted at or soon after admission in patients who are hospitalized for community-acquired pneumonia that is found to be due to Streptococcus pneumoniae. Available data favor the use of a macrolide together with a β-lactam antibiotic for treatment, based largely on immunomodulatory activity of macrolides. Two large subgroup analyses from a single major study suggest that activated protein C (eg, drotrecogin) should be considered for patients with severe sepsis, organ failure, and an Acute Physiology and Chronic Health Evaluation II score > 25 due to pneumococcal pneumonia. Statins exert an anti-inflammatory effect and several retrospective studies suggest that their use might ameliorate the adverse effects of pneumonia. Because inflammation elsewhere in the body is associated with inflammation in coronary arteries and because pneumococcal pneumonia has been shown to precipitate myocardial infarction, statins might be of further benefit by decreasing the likelihood of associated myocardial infarction. Aspirin, which inhibits platelet aggregation in inflamed coronary arteries, might also be considered for initial therapy. One reason that the association between myocardial infarction and pneumonia was not previously recognized is that aspirin was widely used in the past when people had acute febrile conditions. The literature on the benefits of corticosteroids in pneumonia is not convincing, and a particularly well-done, very recent study shows no benefit with corticosteroid use in patients with pneumococcal pneumonia, and perhaps even a worse outcome. No clinical data favor the use of platelet-activating factor antagonists.

Early combination antibiotic therapy yields improved survival compared with monotherapy in septic shock: a propensity-matched analysis

BACKGROUND

Septic shock represents the major cause of infection-associated mortality in the intensive care unit. The possibility that combination antibiotic therapy of bacterial septic shock improves outcome is controversial. Current guidelines do not recommend combination therapy except for the express purpose of broadening coverage when resistant pathogens are a concern.

OBJECTIVE

To evaluate the therapeutic benefit of early combination therapy comprising at least two antibiotics of different mechanisms with in vitro activity for the isolated pathogen in patients with bacterial septic shock.

DESIGN

Retrospective, propensity matched, multicenter, cohort study.

SETTING

Intensive care units of 28 academic and community hospitals in three countries between 1996 and 2007.

SUBJECTS

A total of 4662 eligible cases of culture-positive, bacterial septic shock treated with combination or monotherapy from which 1223 propensity-matched pairs were generated.

MEASUREMENTS AND MAIN RESULTS

The primary outcome of study was 28-day mortality. Using a Cox proportional hazards model, combination therapy was associated with decreased 28-day mortality (444 of 1223 [36.3%] vs. 355 of 1223 [29.0%]; hazard ratio, 0.77; 95% confidence interval, 0.67-0.88; p = .0002). The beneficial impact of combination therapy applied to both Gram-positive and Gram-negative infections but was restricted to patients treated with beta-lactams in combination with aminoglycosides, fluoroquinolones, or macrolides/clindamycin. Combination therapy was also associated with significant reductions in intensive care unit (437 of 1223 [35.7%] vs. 352 of 1223 [28.8%]; odds ratio, 0.75; 95% confidence interval, 0.63-0.92; p = .0006) and hospital mortality (584 of 1223 [47.8%] vs. 457 of 1223 [37.4%]; odds ratio, 0.69; 95% confidence interval, 0.59-0.81; p < .0001). The use of combination therapy was associated with increased ventilator (median and [interquartile range], 10 [0-25] vs. 17 [0-26]; p = .008) and pressor/inotrope-free days (median and [interquartile range], 23 [0-28] vs. 25 [0-28]; p = .007) up to 30 days.

CONCLUSION

Early combination antibiotic therapy is associated with decreased mortality in septic shock. Prospective randomized trials are needed.

Nationwide surveillance of Streptococcus pneumoniae in Greece: patterns of resistance and serotype epidemiology

This nationwide study assessed the antimicrobial susceptibility and seroprevalence of Streptococcus pneumoniae in paediatric carriage isolates and in clinical isolates from adult pneumococcal disease in Greece during the years 2004-2006. Among 780 isolates recovered from the nasopharynx of children <6 years old attending day-care centres, non-susceptibility rates to penicillin, cefuroxime, ceftriaxone, erythromycin, tetracycline and trimethoprim/sulfamethoxazole were 34.7%, 25.1%, 1.0%, 33.5%, 26.4% and 44.2%, respectively. Among 89 adult clinical isolates, the respective rates were 48.3%, 46.1%, 5.6%, 48.3%, 32.6% and 40.4%. High-level resistance to penicillin, cefuroxime and ceftriaxone was recorded for 14.4%, 23.3% and 0.1% of paediatric carriage isolates, whereas for clinical adult isolates the respective rates were 25.8%, 38.2% and 2.2%. No resistance to levofloxacin and moxifloxacin was recorded, although 3.5% of paediatric carriage isolates and 23.2% of adult clinical isolates had minimum inhibitory concentrations of ciprofloxacin >2mg/L. Serotypes 19F, 14, 23F and 6B were the most prevalent among carriage and clinical isolates. The 7-valent pneumococcal conjugate vaccine was estimated to provide coverage against 71.7% of paediatric carriage isolates and 51.3% of adult clinical isolates. Resistance rates among clinical isolates from adult sources were higher than those recorded among paediatric carriage S. pneumoniae isolates and displayed an increasingly resistant profile compared with previous reports from our country, warranting continuous vigilance.