Impact of macrolide therapy in patients hospitalized with Pseudomonas aeruginosa community-acquired pneumonia

Azithromycin and Major Adverse Kidney Events in Critically Ill Patients With Sepsis-Associated Acute Kidney Injury

BACKGROUND

Sepsis-associated acute kidney injury (SA-AKI) is associated with significant morbidity and mortality. Immune dysregulation is a hallmark of sepsis, with important contributions to organ dysfunction including injury and repair mechanisms in AKI. Macrolide antibiotics, such as azithromycin, have previously demonstrated in preclinical models a myriad of immunomodulatory effects that may benefit critically ill patients with SA-AKI. The aim of this study was to determine if early receipt of azithromycin in SA-AKI is associated with a reduction in major adverse kidney events (MAKE) at hospital discharge.

METHODS

This was a single center, retrospective cohort study of critically ill adult patients with SA-AKI. Early exposure to azithromycin was defined as receipt of one or more doses within 48 h of a hospital admission with SA-AKI. The primary outcome of MAKE assessed at hospital discharge was the composite of death, requirement for kidney replacement therapy, or a decline in estimated glomerular filtration rate of 25% or more. Multivariable logistic regression was used to account for potential confounders in the assessment.

RESULTS

Of 737 included patients with SA-AKI, 152 (20.6%) received azithromycin. Patients that received early azithromycin were less likely to experience MAKE at hospital discharge when compared to those patients not receiving azithromycin: 38.8% versus 48.4% (P = 0.035). In multivariable logistic regression, receipt of azithromycin was independently associated with a decreased odds of MAKE at hospital discharge (aOR 0.62, 95% CI 0.41-0.93).

CONCLUSIONS

Early exposure to azithromycin in SA-AKI is independently associated with lower odds of MAKE at hospital discharge.

Could Azithromycin Be Part of Pseudomonas aeruginosa Acute Pneumonia Treatment?

Azithromycin (AZM) is a 15-membered-ring macrolide that presents a broad-spectrum antimicrobial activity against Gram-positive bacteria and atypical microorganisms but suffers from a poor diffusion across the outer-membrane of Gram-negative bacilli, including Pseudomonas aeruginosa (PA). However, AZM has demonstrated clinical benefits in patients suffering from chronic PA respiratory infections, especially cystic fibrosis patients. Since the rise of multidrug-resistant PA has led to a growing need for new therapeutic options, this macrolide has been proposed as an adjunctive therapy. Clinical trials assessing AZM in PA acute pneumonia are scarce. However, a careful examination of the available literature provides good rationales for its use in that context. In fact, 14- and 15-membered-ring macrolides have demonstrated immunomodulatory and immunosuppressive effects that could be of major interest in the management of acute illness. Furthermore, growing evidence supports a downregulation of PA virulence dependent on direct interaction with the ribosomes, and based on the modulation of several key regulators from the Quorum Sensing network. First highlighted in vitro, these interesting properties of AZM have subsequently been confirmed in the animal models. In this review, we systematically analyzed the literature regarding AZM immunomodulatory and anti-PA effects. In vitro and in vivo studies, as well as clinical trials were reviewed, looking for rationales for AZM use in PA acute pneumonia.

Immunomodulation by macrolides: therapeutic potential for critical care

Critical illness is associated with immune dysregulation, characterised by concurrent hyperinflammation and immune suppression. Hyperinflammation can result in collateral tissue damage and organ failure, whereas immune suppression has been implicated in susceptibility to secondary infections and reactivation of latent viruses. Macrolides are a class of bacteriostatic antibiotics that are used in the intensive care unit to control infections or to alleviate gastrointestinal dysmotility. Yet macrolides also have potent and wide-ranging immunomodulatory properties, which might have the potential to correct immune dysregulation in patients who are critically ill without affecting crucial antimicrobial defences. In this Review, we provide an overview of preclinical and clinical studies that point to the beneficial effects of macrolides in acute diseases relevant to critical care, and we discuss the possible underlying mechanisms of their immunomodulatory effects. Further studies are needed to explore the therapeutic potential of macrolides in critical illness, to identify subgroups of patients who might benefit from treatment, and to develop novel non-antibiotic macrolide derivatives with improved immunomodulatory properties.

Rational approach in the management of Pseudomonas aeruginosa infections

PURPOSE OF REVIEW

This review details the management of Pseudomonas aeruginosa infections covering both current and future treatment options that are and may be available for the clinicians.

RECENT FINDINGS

Pseudomonas aeruginosa infections are a great concern in hospital-acquired infections with very limited therapeutic options. The increasing antibiotic resistance has led to a need for different treatment choices that range from the use of new antibiotics to new nonantibiotic alternative agents to kill or disarm the pathogen.

SUMMARY

New molecules such as ceftolozane-tazobactam, ceftazidime-avibactam, and imipenem-relebactam have shown an adequate activity against P. aeruginosa, especially against multidrug resistance strains. Other nonantibiotic alternative treatments, such as antibodies, bacteriocins or phage therapy, have shown promising results, but future clinical studies are needed.

Pneumonia as a cardiovascular disease

Community-acquired pneumonia (CAP) is an important cause of death around the globe. Up to 30% of patients admitted to hospital for CAP develop cardiovascular complications (i.e. new/worsening heart failure, new/worsening arrhythmias, myocardial infarctions and/or strokes), acutely and up to 10 years thereafter. Cardiac complications result from complex interactions between preexisting conditions, relative ischaemia, upregulation of the sympathetic system, systemic inflammation and direct pathogen-mediated damage to the cardiovascular system. The exact mechanisms underlying the direct host-pathogen interactions are of great interest to identify potential therapeutic and preventative targets for CAP. In this review, we summarize the epidemiological data, risk factors and the pathogen-driven cardiovascular damage affecting patients with CAP.

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.

Antibiotic therapy, supportive treatment and management of immunomodulation-inflammation response in community acquired pneumonia: review of recommendations

Community-acquired pneumonia is a common and serious disease, with high rates of morbidity and mortality. Management and treatment of community-acquired pneumonia are described in three main documents: the 2007 American Thoracic Society guidelines, the 2011 European Respiratory Society guidelines, and the 2009 British Thoracic Society guidelines, updated by the NICE in 2015. Despite the validity of current guidelines in improving prognosis and management of patients with community-acquired pneumonia, not all recommendations have high levels of evidence and there are still some controversial issues. In particular, there are some areas of low evidence such as the efficacy of an antibiotic molecule or scheme in patients with same risk factors; duration of antibiotic treatment, supportive therapy for acute respiratory failure and immunomodulation molecules.

This review will summarize the main recommendations with high level of evidence and discuss the recommendations with lower evidence, analyzing the studies published after the guidelines’ release.

The Nonantibiotic Macrolide EM703 Improves Survival in a Model of Quinolone-Treated Pseudomonas aeruginosa Airway Infection

Macrolide antibiotics are used as anti-inflammatory agents, e.g., for prevention of exacerbations in chronic obstructive pulmonary disease and cystic fibrosis. Several studies have shown improved outcomes after the addition of macrolides to β-lactam antibiotics for treatment of severe community-acquired pneumonia. However, a beneficial effect of macrolides in treating Gram-negative bacterial airway infections, e.g., those caused by Pseudomonas aeruginosa, remains to be shown. Macrolide antibiotics have significant side effects, in particular, motility-stimulating activity in the gastrointestinal tract and promotion of bacterial resistance. In this study, EM703, a modified macrolide lacking antibiotic and motility-stimulating activities but with retained anti-inflammatory properties, was used as an adjunct treatment for experimental P. aeruginosa lung infection, in combination with a conventional antibiotic. Airway infections in BALB/cJRj mice were induced by nasal instillation of P. aeruginosa; this was followed by treatment with the quinolone levofloxacin in the absence or presence of EM703. Survival, inflammatory responses, and cellular influx to the airways were monitored. Both pretreatment and simultaneous administration of EM703 dramatically improved survival in levofloxacin-treated mice with P. aeruginosa airway infections. In addition, EM703 reduced the levels of proinflammatory cytokines, increased the numbers of leukocytes in bronchoalveolar lavage fluid, and reduced the numbers of neutrophils present in lung tissue. In summary, the findings of this study show that the immunomodulatory properties of the modified macrolide EM703 can be important when treating Gram-negative pneumonia, as exemplified by P. aeruginosa infection in this study.

Update on the combination effect of macrolide antibiotics in community-acquired pneumonia

Community-acquired pneumonia (CAP) is a leading cause of death from an infectious cause worldwide. Guideline-concordant antibiotic therapy initiated in a timely manner is associated with improved treatment responses and patient outcomes. In the post-antibiotic era, much of the morbidity and mortality of CAP is as a result of the interaction between bacterial virulence factors and host immune responses. In patients with severe CAP, or who are critically ill, there is a lot of emerging observational evidence demonstrating improved survival rates when treatment using combination therapy with a β-lactam and a macrolide is initiated, as compared to other antibiotic regimes without a macrolide. Macrolides in combination with a β-lactam antibiotic provide broader coverage for the atypical organisms implicated in CAP, and may contribute to antibacterial synergism. However, it has been postulated that the documented immunomodulatory effects of macrolides are the primary mechanism for improved patient outcomes through attenuation of bacterial virulence factors and host systemic inflammatory responses. Despite concerns regarding the limitations of observational evidence and the lack of confirmatory randomized controlled trials, the potential magnitude of mortality benefits estimated at 20-50% cannot be overlooked. In light of recent data from a number of trials showing that combination treatment with a macrolide and a suitable second agent is justified in all patients with severe CAP, such treatment should be obligatory for those admitted to an intensive care setting.

Recent advances in our understanding of Streptococcus pneumoniae infection

A number of significant challenges remain with regard to the diagnosis, treatment, and prevention of infections with Streptococcus pneumoniae (pneumococcus), which remains the most common bacterial cause of community-acquired pneumonia. Although this infection is documented to be extremely common in younger children and in older adults, the burden of pneumonia it causes is considerably underestimated, since the incidence statistics are derived largely from bacteremic infections, because they are easy to document, and yet the greater burden of pneumococcal pneumonias is non-invasive. It has been estimated that for every bacteremic pneumonia that is documented, three non-bacteremic infections occur. Management of these infections is potentially complicated by the increasing resistance of the isolates to the commonly used antibiotics. Furthermore, it is well recognized that despite advances in medical care, the mortality of bacteremic pneumococcal pneumonia has remained largely unchanged over the past 50 years and averages approximately 12%. Much recent research interest in the field of pneumococcal infections has focused on important virulence factors of the organism, on improved diagnostic and prognostication tools, on defining risk factors for death, on optimal treatment strategies involving both antibiotics and adjunctive therapies, and on disease prevention. It is hoped that through these endeavors the outlook of pneumococcal infections will be improved.