Community-Acquired Pneumonia Due to Multidrug- and Non-Multidrug-Resistant Pseudomonas aeruginosa

Microbiology of Severe Community-Acquired Pneumonia and the Role of Rapid Molecular Techniques

The microbiology of severe community acquired pneumonia (SCAP) has implications on management, clinical outcomes and public health policy. Therefore, knowledge of the etiologies of SCAP and methods to identify these microorganisms is key. Bacteria including Streptococcus pneumoniae, Staphylococcus aureus and Enterobacteriaceae continue to be important causes of SCAP. Viruses remain the most commonly identified etiology of SCAP. Atypical organisms are also important etiologies of SCAP and are critical to identify for public health. With the increased number of immunocompromised individuals, less common pathogens may also be found as the causative agent of SCAP. Traditional diagnostic tests, including semi-quantitative respiratory cultures, blood cultures and urinary antigens continue to hold an important role in the evaluation of patients with SCAP. Many of the limitations of the aforementioned tests are addressed by rapid, molecular diagnostic tests. Molecular diagnostics utilize culture-independent technology to identify species-specific genetic sequences. These tests are often semi-automated and provide results within hours, which provides an opportunity for expedient antibiotic stewardship. The existing literature suggests molecular diagnostic techniques may improve antibiotic stewardship in CAP, and future research should investigate optimal methods for implementation of these assays into clinical practice.

Is the fluoroquinolone combination necessary for empirical antibiotic regimen in severe community-acquired pneumonia?

OBJECTIVES

This study aimed to assess whether superior clinical outcomes can be attained through piperacillin/tazobactam (TZP)+fluoroquinolone (FQ) combination therapy for severe community-acquired pneumonia (CAP) compared to TZP monotherapy.

METHODS

This retrospective study was conducted at a tertiary care hospital in Korea. Adult inpatients diagnosed with pneumonia within 48 hours of hospitalization were included. Severe CAP was defined as a CURB-65 score of ≥ 3 or based on the 2007 guidelines of the Infectious Diseases Society of America/American Thoracic Society (IDSA/ATS) definition. Only patients who received either TZP and FQ combination or TZP as initial empirical therapy were included.

RESULTS

The final analysis included 145 patients; 57.9% received combination therapy and 42.1% received monotherapy. In the combination therapy group, body mass index (20.67 ± 3.28 vs. 22.26 ± 4.80, p = 0.030) and asthma prevalence (0 vs. 8.3%, p = 0.022) were significantly higher; initial symptoms, clinical severity, and causative pathogens were not significantly different between groups. White blood cell counts (12,641.64 ± 6,544.66 vs. 12,491.67 ± 10,528.24, p = 0.008), and C-reactive protein levels (18.78 ± 11.47 vs. 26.58 ± 14.97, p < 0.001) were significantly higher in the combination therapy group. Clinical outcomes, including all-cause in-hospital mortality rate (26.2 vs. 33.3%, p = 0.358), were not significantly different between the groups. Multivariate analysis identified no significant association between FQ combination and all-cause in-hospital mortality.

CONCLUSION

In patients with severe CAP, there were no differences in the clinical outcomes, including mortality, between the TZP and FQ combination therapy and TZP monotherapy. FQ combination was not significantly associated with in-hospital mortality.

A score to predict Pseudomonas aeruginosa infection in older patients with community-acquired pneumonia

BACKGROUND

In Thailand, the incidence of community-acquired pseudomonal pneumonia among 60- to 65-year-olds ranges from 10.90% to 15.51%, with a mortality rate of up to 19.00%. Antipseudomonal agents should be selected as an empirical treatment for elderly patients at high risk for developing this infection. The purpose of this study was to identify risk factors and develop a risk predictor for Pseudomonas aeruginosa infection in older adults with community-acquired pneumonia (CAP).

METHODS

A retrospective data collection from an electronic database involved the elderly hospitalized patients with P. aeruginosa- and non-P. aeruginosa-causing CAP, admitted between January 1, 2016, and June 30, 2021. Risk factors for P. aeruginosa infection were analysed using logistic regression, and the instrument was developed by scoring each risk factor based on the beta coefficient and evaluating discrimination and calibration using the area under the receiver operating characteristic curve (AuROC) and observed versus predicted probability (E/O) ratio.

RESULTS

The inclusion criteria were met by 81 and 104 elderly patients diagnosed with CAP caused by P. aeruginosa and non-P. aeruginosa, respectively. Nasogastric (NG) tube feeding (odd ratios; OR = 40.68), bronchiectasis (B) (OR = 4.13), immunocompromised condition (I) (OR = 3.76), and other chronic respiratory illnesses (r) such as atelectasis, pulmonary fibrosis, and lung bleb (OR = 2.61) were the specific risk factors for infection with P. aeruginosa. The "60-B-r-I-NG" risk score was named after the 4 abbreviated risk variables and found to have good predicative capability (AuROC = 0.77) and accuracy comparable to or near true P. aeruginosa infection (E/O = 1). People who scored at least two should receive empirically antipseudomonal medication.

CONCLUSIONS

NG tube feeding before admission, bronchiectasis, immunocompromisation, atelectasis, pulmonary fibrosis and lung bleb were risk factors for pseudomonal CAP in the elderly. The 60-B-r-I-NG was developed for predicting P. aeruginosa infection with a high degree of accuracy, equal to or comparable to the existing P. aeruginosa infection. Antipseudomonal agents may be started in patients who are at least 60 years old and have a score of at least 2 in order to lower mortality and promote the appropriate use of these medications.

Pseudomonas aeruginosa: Infections and novel approaches to treatment "Knowing the enemy" the threat of Pseudomonas aeruginosa and exploring novel approaches to treatment

Pseudomonas aeruginosa is an aerobic Gram-negative rod-shaped bacterium with a comparatively large genome and an impressive genetic capability allowing it to grow in a variety of environments and tolerate a wide range of physical conditions. This biological flexibility enables the P. aeruginosa to cause a broad range of infections in patients with serious underlying medical conditions, and to be a principal cause of health care associated infection worldwide. The clinical manifestations of P. aeruginosa include mostly health care associated infections and community-acquired infections. P. aeruginosa possesses an array of virulence factors that counteract host defence mechanisms. It can directly damage host tissue while utilizing high levels of intrinsic and acquired antimicrobial resistance mechanisms to counter most classes of antibiotics. P. aeruginosa co-regulates multiple resistance mechanisms by perpetually moving targets poses a significant therapeutic challenge. Thus, there is an urgent need for novel approaches in the development of anti-Pseudomonas agents. Here we review the principal infections caused by P. aeruginosa and we discuss novel therapeutic options to tackle antibiotic resistance and treatment of P. aeruginosa infections that may be further developed for clinical practice.

Identify Drug-Resistant Pathogens in Patients with Community-Acquired Pneumonia

A substantial increase in broad-spectrum antibiotics as empirical therapy in patients with community-acquired pneumonia (CAP) has occurred over the last 15 years. One of the driving factors leading to that has been some evidence showing an increased incidence of drug-resistant pathogens (DRP) in patients from a community with pneumonia, including methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. Research has been published attempting to identify DRP in CAP through the implementation of probabilistic approaches in clinical practice. However, recent epidemiological data showed that the incidence of DRP in CAP varies significantly according to local ecology, healthcare systems and countries where the studies were performed. Several studies also questioned whether broad-spectrum antibiotic coverage might improve outcomes in CAP, as it is widely documented that broad-spectrum antibiotics overuse is associated with increased costs, length of hospital stay, drug adverse events and resistance. The aim of this review is to analyze the different approaches used to identify DRP in CAP patients as well as the outcomes and adverse events in patients undergoing broad-spectrum antibiotics.

PlyKp104, a Novel Phage Lysin for the Treatment of Klebsiella pneumoniae, Pseudomonas aeruginosa, and Other Gram-Negative ESKAPE Pathogens

Klebsiella pneumoniae and Pseudomonas aeruginosa are two leading causes of burn and wound infections, pneumonia, urinary tract infections, and more severe invasive diseases, which are often multidrug resistant (MDR) or extensively drug resistant. Due to this, it is critical to discover alternative antimicrobials, such as bacteriophage lysins, against these pathogens. Unfortunately, most lysins that target Gram-negative bacteria require additional modifications or outer membrane permeabilizing agents to be bactericidal. We identified four putative lysins through bioinformatic analysis of Pseudomonas and Klebsiella phage genomes in the NCBI database and then expressed and tested their intrinsic lytic activity in vitro. The most active lysin, PlyKp104, exhibited >5-log killing against K. pneumoniae, P. aeruginosa, and other Gram-negative representatives of the multidrug-resistant ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, K. pneumonia, Acinetobacter baumannii, P. aeruginosa, and Enterobacter species) without further modification. PlyKp104 displayed rapid killing and high activity over a wide pH range and in high concentrations of salt and urea. Additionally, pulmonary surfactants and low concentrations of human serum did not inhibit PlyKp104 activity in vitro. PlyKp104 also significantly reduced drug-resistant K. pneumoniae >2 logs in a murine skin infection model after one treatment of the wound, suggesting that this lysin could be used as a topical antimicrobial against K. pneumoniae and other MDR Gram-negative infections.

A Fatal Case of Pseudomonas aeruginosa Community-Acquired Pneumonia in an Immunocompetent Patient: Clinical and Molecular Characterization and Literature Review

Rare cases of Pseudomonas aeruginosa community-acquired pneumonia (PA-CAP) were reported in non-immunocompromised patients. We describe a case of Pseudomonas aeruginosa (PA) necrotizing cavitary CAP with a fatal outcome in a 53-year-old man previously infected with SARS-CoV-2, who was admitted for dyspnea, fever, cough, hemoptysis, acute respiratory failure and a right upper lobe opacification. Six hours after admission, despite effective antibiotic therapy, he experienced multi-organ failure and died. Autopsy confirmed necrotizing pneumonia with alveolar hemorrhage. Blood and bronchoalveolar lavage cultures were positive for PA serotype O:9 belonging to ST1184. The strain shares the same virulence factor profile with reference genome PA01. With the aim to better investigate the clinical and molecular characteristics of PA-CAP, we considered the literature of the last 13 years concerning this topic. The prevalence of hospitalized PA-CAP is about 4% and has a mortality rate of 33-66%. Smoking, alcohol abuse and contaminated fluid exposure were the recognized risk factors; most cases presented the same symptoms described above and needed intensive care. Co-infection of PA-influenza A is described, which is possibly caused by influenza-inducing respiratory epithelial cell dysfunction: the same pathophysiological mechanism could be assumed with SARS-CoV-2 infection. Considering the high rate of fatal outcomes, additional studies are needed to identify sources of infections and new risk factors, along with genetic and immunological features. Current CAP guidelines should be revised in light of these results.

Clinical relevance of bronchiectasis in patients with community-acquired pneumonia

BACKGROUND

Data regarding the clinical characteristics and treatment outcomes of patients with community-acquired pneumonia (CAP) and bronchiectasis (BE) are rare. This study aims to elucidate the clinical relevance of BE in patients with CAP.

METHODS

Patients hospitalized with CAP in a single center were retrospectively analyzed and divided into significant BE (BE with ≥ 3 lobes or cystic BE on computed tomography) and control groups. Clinical and microbiological characteristics were compared between the two groups.

RESULTS

In the final analysis, 2112 patients were included, and 104 (4.9%) had significant BE. The significant BE group exhibited a higher prevalence of sputum production, dyspnea, and complicated parapneumonic effusion or empyema than the control group. Pseudomonas aeruginosa was more frequently isolated in the significant BE group than in the control group, whereas Mycoplasma pneumoniae was less commonly identified. Length of hospital stay (LOS) was significantly longer in the significant BE group than the control group (12 [8-17] days vs. 9 [6-13] days, p < 0.001). In contrast, 30-day and in-hospital mortality rates did not significantly differ between the two groups. Furthermore, significant BE was an independent predictor of prolonged hospitalization in two models based on CURB-65 and pneumonia severity index.

CONCLUSIONS

Significant BE occurred in approximately 5% of patients with CAP and was more likely to be associated with sputum, dyspnea, complicated parapneumonic effusion or empyema, and isolation of P. aeruginosa. Significant BE was an independent predictor of LOS in patients with CAP.

New antibiotics for Gram-negative pneumonia

Pneumonia is frequently encountered in clinical practice, and Gram-negative bacilli constitute a significant proportion of its aetiology, especially when it is acquired in a hospital setting. With the alarming global rise in multidrug resistance in Gram-negative bacilli, antibiotic therapy for treating patients with pneumonia is challenging and must be guided by in vitro susceptibility results. In this review, we provide an overview of antibiotics newly approved for the treatment of pneumonia caused by Gram-negative bacilli. Ceftazidime-avibactam, imipenem-relebactam and meropenem-vaborbactam have potent activity against some of the carbapenem-resistant Enterobacterales, especially Klebsiella pneumoniae carbapenemase producers. Several novel antibiotics have potent activity against multidrug-resistant Pseudomonas aeruginosa, such as ceftazidime-avibactam, ceftolozane-tazobactam, imipenem-relabactam and cefiderocol. Cefiderocol may also play an important role in the management of pneumonia caused by Acinetobacter baumannii, along with plazomicin and eravacycline.

Clinical risk factors for admission with Pseudomonas and multidrug-resistant Pseudomonas community-acquired pneumonia

Background

Microbial etiology for community-acquired pneumonia (CAP) is evolving with pathogens known for high CAP mortality e.g., Pseudomonas species. Chronic obstructive pulmonary disease (COPD) patients are at risk for hospitalization for CAP. Understanding regional patterns and risk factors for multidrug-resistant (MDR) Pseudomonas acquisition has implications for antimicrobial stewardship.

Objectives

To evaluate the regional epidemiology of MDR Pseudomonas CAP and its association with COPD.

Methods

We queried the electronic medical records of the University of Alabama at Birmingham Healthcare System to identify patients hospitalized for CAP with Pseudomonas positive respiratory samples between 01/01/2013–12/31/2019. Log binomial regression models were used to examine associations between COPD diagnosis and risk of Pseudomonas/MDR Pseudomonas CAP.

Results

Cohort consisted of 913 culture positive CAP cases aged 59-year (IQR:48–68), 61% (560) male, 60% (547) white, 65% (580) current/past smokers, and 42% (384) COPD. Prevalence of Pseudomonas CAP in culture positive CAP was 18% (167), MDR Pseudomonas CAP in Pseudomonas CAP was 22% (36), and yearly incidence of MDR Pseudomonas CAP was stable (p = 0.169). COPD was associated with Pseudomonas CAP (RR 1.39; 95% CI 1.01, 1.91; p = 0.041) but not with MDR Pseudomonas CAP (0.71; 95% CI 0.35, 1.45; p = 0.349). Stroke (RR 2.64; 95% CI 1.51, 4.61; p = 0.0006) and use of supplemental oxygen (RR 2.31; 95% CI 1.30, 4.12; p = 0.005) were associated with MDR Pseudomonas CAP.

Conclusion

Incidence of MDR Pseudomonas CAP was stable over time. COPD was associated with Pseudomonas CAP but not with MDR Pseudomonas CAP. Larger cohort studies are needed to confirm findings.

Impact of Pseudomonas aeruginosa coverage on the prognosis of elderly patients with community-acquired pneumonia

BACKGROUND

Although the 2019 American Thoracic Society and Infectious Diseases Society of America guidelines for community-acquired pneumonia (CAP) recommend the use of antibiotics with Pseudomonas aeruginosa coverage for patients with prior sputum isolation of P. aeruginosa, further research is needed to confirm its clinical outcomes. This study aimed to assess the impact of the use of antibiotics with P. aeruginosa coverage on mortality in elderly CAP patients with sputum isolation of P. aeruginosa.

METHODS

We retrospectively included consecutive elderly patients who were hospitalized for CAP and P. aeruginosa-positive sputum culture. The association between the use of antibiotics with P. aeruginosa coverage and 28-day mortality was assessed based on propensity score to reduce selection bias.

RESULTS

A total of 216 patients were included, and 68 (31%) of them were treated with antibiotics with P. aeruginosa coverage. The number of patients treated with antibiotics with P. aeruginosa coverage was significantly higher among nonsurvivors than among survivors. After adjustment using propensity score, the association between the use of antibiotics with P. aeruginosa coverage and the 28-day mortality was found to be statistically nonsignificant (odds ratio 2.182, 95% confidence interval 0.732-6.508, p = 0.162).

CONCLUSIONS

The use of antibiotics with P. aeruginosa coverage in elderly CAP patients with sputum isolation of P. aeruginosa did not improve their prognosis. A randomized control study is required to identify cases that should be treated with antibiotics covering P. aeruginosa.

Treatment Heterogeneity in Pseudomonas aeruginosa Pneumonia

We have previously identified substantial antibiotic treatment heterogeneity, even among organism-specific and site-specific infections with treatment guidelines. Therefore, we sought to quantify the extent of treatment heterogeneity among patients hospitalized with P. aeruginosa pneumonia in the national Veterans Affairs Healthcare System from Jan-2015 to Apr-2018. Daily antibiotic exposures were mapped from three days prior to culture collection until discharge. Heterogeneity was defined as unique patterns of antibiotic treatment (drug and duration) not shared by any other patient. Our study included 5300 patients, of whom 87.5% had unique patterns of antibiotic drug and duration. Among patients receiving any initial antibiotic/s with a change to at least one anti-pseudomonal antibiotic (n = 3530, 66.6%) heterogeneity was 97.2%, while heterogeneity was 91.5% in those changing from any initial antibiotic/s to only anti-pseudomonal antibiotics (n = 576, 10.9%). When assessing heterogeneity of anti-pseudomonal antibiotic classes, irrespective of other antibiotic/s received (n = 4542, 85.7%), 50.5% had unique patterns of antibiotic class and duration, with median time to first change of three days, and a median of two changes. Real-world evidence is needed to inform the development of treatment pathways and antibiotic stewardship initiatives based on clinical outcome data, which is currently lacking in the presence of such treatment heterogeneity.

Community-acquired Pseudomonas aeruginosa pneumonia manifested by bloody pleural effusion in a previously healthy infant: A case report

BACKGROUND

Community-acquired Pseudomonas aeruginosa pneumonia in immunocompetent children is a rare occurrence.

METHODS

A retrospective analysis of the clinical manifestations, imaging characteristics, laboratory examinations, and treatment of a child with community-acquired Pseudomonas aeruginosa pneumonia presented with bloody pleural effusion.

RESULTS

The 1-year-old previously healthy patient, who developed community-acquired pneumonia caused by Pseudomonas aeruginosa and influenza virus. The patient manifested bloody pleural effusion although his condition improved after anti-infective therapy and closed thoracic drainage. After 10 days of hospitalization, his symptoms worsened, accompanied by hemoptysis, and the pathogen developed resistance to carbapenems. The antibiotic strategy was adjusted to combined antipseudomonal regimen. He developed low-grade fever and was extubated, although these manifestations and imaging were eventually alleviated.

CONCLUSIONS

Community-acquired Pseudomonas aeruginosa pneumonia in children may be non-septic, with bloody pleural effusion as presentation, and the disease may progress after 10 days of treatment due to drug resistance in Pseudomonas aeruginosa. Early extubation should be considered after adequate drainage.

Contribution of IL-38 in Lung Immunity during Pseudomonas Aeruginosa-induced Pneumonia

OBJECTIVE

Interleukin-38 (IL-38), a new type of cytokine, is involved in processes such as tissue repair, inflammatory response, and immune response. However, its function in pneumonia caused by Pseudomonas aeruginosa (P. aeruginosa) is still unclear.

METHODS

In this study, we detected circulating IL-38 and cytokines such as IL-1β, IL-6, IL-17A, TNF-α, IL-8, and IL-10 in adults affected by early stage pneumonia caused by P. aeruginosa. Collected clinical data of these patients, such as the APACHE II score, levels of PCT, and oxygenation index when they entering the ICU. Using P. aeruginosa-induced pneumonia WT murine model to evaluate the effect of IL-38 on Treg differentiation, cell apoptosis, survival, tissue damage, inflammation, and bacterial removal.

RESULTS

In clinical research, although IL-38 is significantly increased during the early stages of clinical P. aeruginosa pneumonia, the concentration of IL-38 in the serum of patients who died with P. aeruginosa pneumonia was relatively lower than that of surviving patients. It reveals IL-38 may insufficiently secreted in patients who died with P. aeruginosa pneumonia. Besides, the serum IL-38 level of patients with P. aeruginosa pneumonia on the day of admission to the ICU showed significantly positive correlations with IL-10 and the PaO2/FiO2 ratio but negative correlations with IL-1β, IL-6, IL-8, IL-17, TNF-α, APACHE II score, and PCT In summary, IL-38 might be a molecule for adjuvant therapy in P. aeruginosa pneumonia. In experimental animal models, first recombinant IL-38 improved survival, whereas anti-IL-38 antibody reduced survival in the experimental pneumonia murine model. Secondly, IL-38 exposure reduced the inflammatory response, as suggested by the lung injury, and reduced cytokine levels (IL-1β, IL-6, IL- 17A, TNF-α, and IL-8, but not IL-10). It also increased bacterial clearance and reduced cell apoptosis in the lungs. Furthermore, IL-38 was shown to reduce TBK1 expression in vitro when naive CD4+ T lymphocytes were differentiated to Tregs and played a protective role in P. aeruginosa pneumonia.

CONCLUSIONS

To summarize, the above findings provide additional insights into the mechanism of IL-38 in the treatment of P. aeruginosa pneumonia.

Empiric Treatment in HAP/VAP: “Don’t You Want to Take a Leap of Faith?”

Ventilator-associated pneumonia is a frequent cause of ICU-acquired infections. These infections are associated with high morbidity and mortality. The increase in antibiotic resistance, particularly among Gram-negative bacilli, makes the choice of empiric antibiotic therapy complex for physicians. Multidrug-resistant organisms (MDROs) related infections are associated with a high risk of initial therapeutic inadequacy. It is, therefore, necessary to quickly identify the bacterial species involved and their susceptibility to antibiotics. New diagnostic tools have recently been commercialized to assist in the management of these infections. Moreover, the recent enrichment of the therapeutic arsenal effective on Gram-negative bacilli raises the question of their place in the therapeutic management of these infections. Most national and international guidelines recommend limiting their use to microbiologically documented infections. However, many clinical situations and, in particular, the knowledge of digestive or respiratory carriage by MDROs should lead to the discussion of the use of these new molecules, especially the new combinations with beta-lactamase inhibitors in empirical therapy. In this review, we present the current epidemiological data, particularly in terms of MDRO, as well as the clinical and microbiological elements that may be taken into account in the discussion of empirical antibiotic therapy for patients managed for ventilator-associated pneumonia.

Pseudomonas aeruginosa Pneumonia: Evolution of Antimicrobial Resistance and Implications for Therapy

Pseudomonas aeruginosa (PA), a non-lactose-fermenting gram-negative bacillus, is a common cause of nosocomial infections in critically ill or debilitated patients, particularly ventilator-associated pneumonia (VAP), and infections of urinary tract, intra-abdominal, wounds, skin/soft tissue, and bloodstream. PA rarely affects healthy individuals, but may cause serious infections in patients with chronic structural lung disease, comorbidities, advanced age, impaired immune defenses, or with medical devices (e.g., urinary or intravascular catheters, foreign bodies). Treatment of pseudomonal infections is difficult, as PA is intrinsically resistant to multiple antimicrobials, and may acquire new resistance determinants even while on antimicrobial therapy. Mortality associated with pseudomonal VAP or bacteremias is high (> 35%) and optimal therapy is controversial. Over the past three decades, antimicrobial resistance (AMR) among PA has escalated globally, via dissemination of several international multidrug resistant "epidemic" clones. We discuss the importance of PA as a cause of pneumonia including health care-associated pneumonia, hospital-acquired pneumonia, VAP, the emergence of AMR to this pathogen, and approaches to therapy (both empirical and definitive).

Therapeutic effects of high molecular weight hyaluronic acid in severe Pseudomonas aeruginosa pneumonia in ex vivo perfused human lungs

We previously reported that extracellular vesicles (EVs) released during Escherichia coli (E. coli) bacterial pneumonia were inflammatory, and administration of high molecular weight hyaluronic acid (HMW HA) suppressed several indices of acute lung injury (ALI) from E. coli pneumonia by binding to these inflammatory EVs. The current study was undertaken to study the therapeutic effects of HMW HA in ex vivo perfused human lungs injured with Pseudomonas aeruginosa (PA)103 bacterial pneumonia. For lungs with baseline alveolar fluid clearance (AFC) <10%/h, HMW HA 1 or 2 mg was injected intravenously after 1 h (n = 4-9), and EVs released during PA pneumonia were collected from the perfusate over 6 h. For lungs with baseline AFC > 10%/h, HMW HA 2 mg was injected intravenously after 1 h (n = 6). In vitro experiments were conducted to evaluate the effects of HA on inflammation and bacterial phagocytosis. For lungs with AFC < 10%/h, administration of HMW HA intravenously significantly restored AFC and numerically decreased protein permeability and alveolar inflammation from PA103 pneumonia but had no effect on bacterial counts at 6 h. However, HMW HA improved bacterial phagocytosis by human monocytes and neutrophils and suppressed the inflammatory properties of EVs released during pneumonia on monocytes. For lungs with AFC > 10%/h, administration of HMW HA intravenously improved AFC from PA103 pneumonia but had no significant effects on protein permeability, inflammation, or bacterial counts. In the presence of impaired alveolar epithelial transport capacity, administration of HMW HA improved the resolution of pulmonary edema from Pseudomonas PA103 bacterial pneumonia.

Community-acquired pneumonia: Trends in and research on drug resistance and advances in new antibiotics

Community-acquired pneumonia (CAP) refers to infectious inflammation of the lung parenchyma developing outside of a hospital. CAP has quite a high mortality and morbidity rate worldwide, and especially among elderly patients. The increasing burden of CAP is due to antibiotic resistance, the growth of the elderly population, and underlying comorbidities. Streptococcus pneumoniae remains the most common bacterial pathogen causing CAP, but multi-drug resistance bacteria and potential pathogens have increased the difficulty and challenges of managing CAP. Although preventive measures, diagnostic techniques, and treatment strategies are constantly advancing and improving, the susceptibility of multi-drug resistant pathogens, such as including Methicillin-Resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae, and Pseudomonas aeruginosa, has not improved significantly in recent decades, thus highlighting the importance and necessity of developing new antibiotics for the treatment of CAP. New antimicrobials have been approved over the past few years that will expand treatment options for CAP, and especially for patients with potential comorbidities. This situation also offers the chance to reduce the abuse of antibiotics, their toxicities, and their adverse reactions and to provide effective personalized antibiotic treatment.

Definitive and Indeterminate Pseudomonas aeruginosa Infection in Adults with Community-acquired Pneumonia: A Prospective Observational Study

Rationale: Pneumonia due to Pseudomonas aeruginosa (PA) is associated with high mortality and requires antipseudomonal treatment. Because PA can colonize the respiratory tract, the diagnosis of pathogenic PA involvement is challenging.

Objectives: To determine the prevalence of definitive and indeterminate PA infection in community-acquired pneumonia, to describe the clinical and microbiological profiles, and to estimate the burden of unnecessary antipseudomonal drug prescriptions.

Methods: We prospectively enrolled 2,701 patients with community-acquired pneumonia. Using stringent criteria for diagnosing PA pneumonia, we generated the following three groups: 1) definitive PA, 2) indeterminate PA, and 3) non-PA pneumonia.

Results: The prevalence of definitive PA pneumonia was 0.9% (n = 25), and that of indeterminate PA pneumonia was 4.9% (n = 131). Considerable clinical differences were observed among the groups. Patients with definitive PA pneumonia were more likely to have a history of tuberculosis and chronic obstructive pulmonary disease/bronchiectasis and had a higher 30-day mortality (28%) than patients with non-PA pneumonia. Patients with indeterminate PA pneumonia were more likely to have comorbidities than patients with non-PA pneumonia. More than half of the patients with indeterminate PA and 25% of the patients with non-PA pneumonia were treated with an antipseudomonal drug. No patients with definitive PA pneumonia had multidrug resistance.

Conclusions: In this population, the prevalence of community-acquired pneumonia due to PA was low. The clinical features and 30-day mortality rates of patients with indeterminate PA pneumonia were different from those of patients with definitive PA pneumonia. Most of the prescribed antipseudomonal drugs for patients with community-acquired pneumonia were potentially unnecessary.

Validation of a Prediction Score for Drug-Resistant Microorganisms in Community-acquired Pneumonia

Rationale: Recommended initial empiric antimicrobial treatment covers the most common bacterial pathogens; however, community-acquired pneumonia (CAP) may be caused by microorganisms not targeted by this treatment. Developed in 2015, the PES (Pseudomonas aeruginosa, extended-spectrum β-lactamase-producing Enterobacteriaceae, and methicillin-resistant Staphylococcus aureus) score was developed in 2015 to predict the microbiological etiology of CAP caused by PES microorganisms.Objective: To validate the usefulness of the PES score for predicting PES microorganisms in two cohorts of patients with CAP from Valencia and Mataró.Methods: We analyzed two prospective observational cohorts of patients with CAP from Valencia and Mataró. Patients in the Mataró cohort were all admitted to an intensive care unit (ICU).Results: Of the 1,024 patients in the Valencia cohort, 505 (51%) had a microbiological etiology and 31 (6%) had a PES microorganism isolated. The area under the receiver operating characteristic curve was 0.81 (95% confidence interval [95% CI], 0.74-0.88). For a PES score ≥5, sensitivity, specificity, the negative and positive predictive values as well as the negative and positive likelihood ratios were 72%, 74%, 98%, 14%, 0.38, and 2.75, respectively. Of the 299 patients in the Mataró cohort, 213 (71%) had a microbiological etiology and 11 (5%) had a PES microorganism isolated. The area under the receiver operating characteristic curve was 0.73 (95% CI 0.61-0.86). For a PES score ≥ 5, sensitivity, specificity, the negative and positive predictive values, and the negative and positive likelihood ratios were 36%, 83%, 96%, 11%, 0.77, and 2.09, respectively. The best cutoff for patients admitted to the ICU was 4 points, which improved sensitivity to 86%. The hypothetical application of the PES score showed high rates of overtreatment in both cohorts (26% and 35%, respectively) and similar rates of undertreatment.Conclusions: The PES score showed good accuracy in predicting the risk for microorganisms that required different empirical therapy; however, its use as a single strategy for detecting noncore pathogens could lead to high rates of overtreatment. Given its high negative predictive value, the PES score may be used as a first step of a wider strategy that includes subsequent advanced diagnostic tests.

Successfully controlling the incidence of multidrug-resistant Pseudomonas aeruginosa through antibiotic stewardship and infection control programmes at a Chinese university hospital

WHAT IS KNOWN AND OBJECTIVE

The purpose of this study was to investigate the effect of imposing infection control programmes (ICPs) and antimicrobial stewardship (AMS) by monitoring the antimicrobial resistance of Pseudomonas aeruginosa.

METHODS

Antimicrobial susceptibility testing was performed in accordance with the Clinical and Laboratory Standards Institute and European Committee on Antimicrobial Susceptibility Testing guidelines. ICPs and AMS were initiated at the Fourth Hospital from 2013 to 2018.

RESULTS AND DISCUSSION

A total of 2,886 P. aeruginosa isolates were assessed. The antimicrobial resistance trends of the P. aeruginosa strains improved after the intervention measures. Multidrug-resistant (MDR) and extensively drug-resistant (XDR) P. aeruginosa contributed to 18.5% and 3.5% of the total P. aeruginosa strains, respectively. Colistin was the most effective antibiotic against 97.6% of XDR-P. aeruginosa and 99.41% of MDR-P. aeruginosa. The consumption of alcohol-based hand gel (ABHG) increased from 0.6 L to 10.8 L per 1,000 patient-days (PD) (p = 0.005). The yearly consumption of antibiotics decreased from 45 to 37.5 defined daily doses (DDD) per 1,000 PD(p = 0.04). After 2013, the incidence rate of MDR-P. aeruginosa showed a significant decrease from 22% to 14.1% (p = 0.04), and XDR-P. aeruginosa decreased from 5.8% to 0.9%. The use of ABHG was negatively related to MDR-P. aeruginosa morbidity (r = -0.86; p = 0.021). The consumption of antibiotics was positively related to MDR-P. aeruginosa morbidity (r = 0.86; p = 0.021).

WHAT IS NEW AND CONCLUSION

Successful control of MDR-P. aeruginosa resistance was achieved by imposing comprehensive ICPs and AMS.

Potent Killing of Pseudomonas aeruginosa by an Antibody-Antibiotic Conjugate

Pseudomonas aeruginosa causes life-threatening infections that are associated with antibiotic failure. Previously, we identified the antibiotic G2637, an analog of arylomycin, targeting bacterial type I signal peptidase, which has moderate potency against P. aeruginosa. We hypothesized that an antibody-antibiotic conjugate (AAC) could increase its activity by colocalizing P. aeruginosa bacteria with high local concentrations of G2637 antibiotic in the intracellular environment of phagocytes. Using a novel technology of screening for hybridomas recognizing intact bacteria, we identified monoclonal antibody 26F8, which binds to lipopolysaccharide O antigen on the surface of P. aeruginosa bacteria. This antibody was engineered to contain 6 cysteines and was conjugated to the G2637 antibiotic via a lysosomal cathepsin-cleavable linker, yielding a drug-to-antibody ratio of approximately 6. The resulting AAC delivered a high intracellular concentration of free G2637 upon phagocytosis of AAC-bound P. aeruginosa by macrophages, and potently cleared viable P. aeruginosa bacteria intracellularly. The molar concentration of AAC-associated G2637 antibiotic that resulted in elimination of bacteria inside macrophages was approximately 2 orders of magnitude lower than the concentration of free G2637 required to eliminate extracellular bacteria. This study demonstrates that an anti-P. aeruginosa AAC can locally concentrate antibiotic and kill P. aeruginosa inside phagocytes, providing additional therapeutic options for antibiotics that are moderately active or have an unfavorable pharmacokinetics or toxicity profile.

Role of CD44 in increasing the potency of mesenchymal stem cell extracellular vesicles by hyaluronic acid in severe pneumonia

Background

Although promising, clinical translation of human mesenchymal stem or stromal cell-derived extracellular vesicles (MSC EV) for acute lung injury is potentially limited by significant production costs. The current study was performed to determine whether pretreatment of MSC EV with high molecular weight hyaluronic acid (HMW HA) would increase the therapeutic potency of MSC EV in severe bacterial pneumonia.

Methods

In vitro experiments were performed to determine the binding affinity of HMW HA to MSC EV and its uptake by human monocytes, and whether HMW HA primed MSC EV would increase bacterial phagocytosis by the monocytes. In addition, the role of CD44 receptor on MSC EV in the therapeutic effects of HMW HA primed MSC EV were investigated. In Pseudomonas aeruginosa (PA) pneumonia in mice, MSC EV primed with or without HMW HA were instilled intravenously 4 h after injury. After 24 h, the bronchoalveolar lavage fluid, blood, and lungs were analyzed for levels of bacteria, inflammation, MSC EV trafficking, and lung pathology.

Results

MSC EV bound preferentially to HMW HA at a molecular weight of 1.0 MDa compared with HA with a molecular weight of 40 KDa or 1.5 MDa. HMW HA primed MSC EV further increased MSC EV uptake and bacterial phagocytosis by monocytes compared to treatment with MSC EV alone. In PA pneumonia in mice, instillation of HMW HA primed MSC EV further reduced inflammation and decreased the bacterial load by enhancing the trafficking of MSC EV to the injured alveolus. CD44 siRNA pretreatment of MSC EV prior to incubation with HMW HA eliminated its trafficking to the alveolus and therapeutic effects.

Conclusions

HMW HA primed MSC EV significantly increased the potency of MSC EV in PA pneumonia in part by enhancing the trafficking of MSC EV to the sites of inflammation via the CD44 receptor on MSC EV which was associated with increased antimicrobial activity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02329-2.

Pseudomonas aeruginosa: a clinical and genomics update

Antimicrobial resistance (AMR) has become a global medical priority that needs urgent resolution. Pseudomonas aeruginosa is a versatile, adaptable bacterial species with widespread environmental occurrence, strong medical relevance, a diverse set of virulence genes and a multitude of intrinsic and possibly acquired antibiotic resistance traits. P. aeruginosa causes a wide variety of infections and has an epidemic-clonal population structure. Several of its dominant global clones have collected a wide variety of resistance genes rendering them multi-drug resistant (MDR) and particularly threatening groups of vulnerable individuals including surgical patients, immunocompromised patients, Caucasians suffering from cystic fibrosis (CF) and more. AMR and MDR especially are particularly problematic in P. aeruginosa significantly complicating successful antibiotic treatment. In addition, antimicrobial susceptibility testing (AST) of P. aeruginosa can be cumbersome due to its slow growth or the massive production of exopolysaccharides and other extracellular compounds. For that reason, phenotypic AST is progressively challenged by genotypic methods using whole genome sequences (WGS) and large-scale phenotype databases as a framework of reference. We here summarize the state of affairs and the quality level of WGS-based AST for P. aeruginosa mostly from clinical origin.

Kidney disease and mortality in patients with respiratory tract infections: a systematic review and meta-analysis

BACKGROUND

Respiratory tract infections (RTIs) are a common reason for people to seek medical care. RTIs are associated with high short-term mortality. Inconsistent evidence exists in the association between the presence of kidney disease and the risk of death in patient with RTIs.

METHODS

We searched the PubMed, Cochrane Library and Embase databases from inception through April 2019 for cohort and case-control studies investigating the presence of kidney disease (defined as medical diagnosis of kidney disease, reduced estimated glomerular filtration rate or creatinine clearance, elevated serum creatinine and proteinuria) on mortality in adults with RTIs in different settings including community, inpatient and intensive care units. We assessed the quality of the included studies using Cochrane Collaboration's tool and conducted a meta-analysis on the relative risk (RR) of death.

RESULTS

Of 5362 records identified, 18 studies involving 16 676 participants met the inclusion criteria, with 15 studies investigating pneumonia and 3 studies exploring influenza. The risk of bias in the available evidence was moderate. Most [17/18 (94.5%)] of studies reported positive associations of underlying chronic kidney disease with mortality. The pooled adjusted risk for all-cause mortality in patients with RTIs almost doubled [RR 1.96 (95% confidence interval 1.48-2.59)] in patients with kidney disease. Associations were consistent across different timings of kidney disease assessment and provenances of RTIs (community-acquired or healthcare-associated).

CONCLUSIONS

The presence of kidney disease is associated with higher mortality among people with RTIs, especially in those with pneumonia. The presence of kidney disease might be taken into account when considering admission for patients who present with RTIs.

Pseudomonas aeruginosa infection in intensive care: Epidemiology, outcomes, and antimicrobial susceptibilities

BACKGROUND

Pseudomonas aeruginosa (PA) infection in the intensive care unit (ICU) contributes to substantial mortality. In this study, we describe the epidemiology, antimicrobial susceptibilities, and outcomes of ICU patients with pseudomonal infection.

METHODS

ICU patients with PA were identified and classified as colonized or infected. Infected patients were reviewed for source, patient characteristics, antimicrobial susceptibilities, appropriateness of empiric antimicrobial therapy, and 30-day mortality. Independent predictors of mortality were identified using multivariable logistic regression.

RESULTS

One hundred forty (71%) patients with PA were infected. Mean patient age was 55 (SD 18) years; 62% were male. Admission categories included medical (71%), surgical (20%), and trauma or neurological (9%). Mean Acute Physiology and Chronic Health Evaluation (APACHE) II score was 19 (SD 10). One hundred twenty-six (90%) patients were mechanically ventilated, 102 (73%) required vasopressors, and 27 (19%) received renal replacement; 32 (23%) died within 30 days. Infection was nosocomial in 101 (72%) cases. Sources were respiratory (66%), skin-soft tissue (11%), urinary (10%), blood (5%), surgical (5%), gastrointestinal (2%), or unknown (1%). Twenty (14%) isolates were multi-drug resistant; 6 (4%) were extensively drug resistant. Empiric antimicrobial therapy was effective in 97 (69%) cases. Liver disease (adjusted OR [aOR] 6.2, 95% CI 1.5 to 25.7; p = 0.01), malignancy (aOR 5.0, 95% CI 1.5 to 17.3; p = 0.01), and higher APACHE II score (aOR 1.1, 95% CI 1.0 to 1.1; p = 0.02) were independently associated with 30-day mortality.

CONCLUSIONS

PA infection in ICU is most commonly respiratory and associated with substantial mortality. Existing malignancy, liver disease, and higher APACHE II score were independently associated with mortality.

A multiplex polymerase chain reaction assay for antibiotic stewardship in suspected pneumonia

Background

Multiplexed molecular rapid diagnostic tests (RDTs) may allow for rapid and accurate diagnosis of the microbial etiology of pneumonia. However, little data are available on multiplexed RDTs in pneumonia and their impact on clinical practice.

Methods

This retrospective study analyzed 659 hospitalized patients for microbiological diagnosis of suspected pneumonia.

Results

The overall sensitivity of the Unyvero LRT Panel was 85.7% (95% CI 82.3–88.7) and the overall specificity was 98.4% (95% CI 98.2–98.7) with a negative predictive value of 97.9% (95% CI 97.6–98.1). The LRT Panel result predicted no change in antibiotics in 12.4% of cases but antibiotic de-escalation in 65.9% (405/615) of patients, of whom 278/405 (69%) had unnecessary MRSA coverage and 259/405 (64%) had unnecessary P. aeruginosa coverage.

Interpretation

In hospitalized adults with suspected pneumonia, use of an RDT on respiratory samples can allow for early adjustment of initial antibiotics, most commonly de-escalation.

Risk Factors of Multidrug-Resistant Bacteria in Lower Respiratory Tract Infections: A Systematic Review and Meta-Analysis

Background

Multidrug-resistant (MDR) bacteria are the main cause of lower respiratory tract infections (LRTIs) with high mortality. The purpose of this study is to identify the risk factors associated with MDR by performing a systematic review and meta-analysis.

Methods

PubMed, EMBASE (via Ovid), and Cochrane Library were systematically searched for studies on the risk factors for MDR bacteria in LRTIs as of November 30, 2019. Literature screening, data abstraction, and quality assessment of the eligible studies were performed independently by two researchers.

Results

A total of 3,607 articles were retrieved, of which 21 articles representing 20 cohort studies published in English were included after title/abstract and full-text screening. Among the 21 articles involving 7,650 patients and 1,360 MDR organisms, ten reported the risk factors for MDR Gram-positive bacteria (GPB) and Gram-negative bacteria (GNB), ten for MDR GNB, and one for MDR GPB. The meta-analysis results suggested that prior antibiotic treatment, inappropriate antibiotic therapy, chronic lung disease, chronic liver disease and cerebral disease, prior MDR and PA infection/colonization, recent hospitalization, longer hospitalization stay, endotracheal tracheostomy and mechanical ventilation, tube feeding, nursing home residence, and higher disease severity score were independent risk factors for MDR bacteria.

Conclusions

This review identified fourteen clinical factors that might increase the risk of MDR bacteria in patients with LRTIs. Clinicians could take into account these factors when selecting antibiotics for patients and determine whether coverage for MDR bacteria is required. More well-designed studies are needed to confirm the various risk factors for MDR bacteria in the future.

New antibiotics for community-acquired pneumonia

PURPOSE OF REVIEW

This review provides the rationale for the development of new antibiotics to treat community-acquired pneumonia (CAP). It also provides an overview of the new antibiotics targeting CAP that have recently received approval by the regulatory agencies, and those antibiotics that are in the development pipeline.

RECENT FINDINGS

CAP is one of the most common reasons for hospitalization and carries a significant morbidity and risk of mortality. Increasing antibiotic resistance amongst the common bacterial pathogens associated with CAP, especially staphylococci and Streptococcus pneumoniae, has made the empiric treatment of this infection increasingly problematic. Moreover, failure of initial empiric therapy to cover the causative agents associated with CAP can be associated with worse clinical outcomes. There have been several antibiotics newly approved or in development for the treatment of CAP. These agents include delafloxacin, omadacycline, lefamulin, solithromycin, nemonoxacin, and ceftaroline. Their major advantages include activity against methicillin-resistant Staphylococcus aureus and macrolide-resistant Strep. pneumoniae.

SUMMARY

CAP continues to be an important infection because of its impact on patient outcomes especially in the elderly and immunocompromised hosts. The availability of new antibiotics offers an opportunity for enhanced empiric treatment of the antibiotic-resistant bacterial pathogens associated with CAP.

Determinants of empirical antipseudomonal antibiotic prescription for adults with pneumonia in the emergency department

Background

Antipseudomonal antibiotics should be restricted to patients at risk of Pseudomonas aeruginosa infection. However, the indications in different guidelines on community-acquired pneumonia (CAP) are discordant. Our objectives were to assess the prevalence of antipseudomonal antibiotic prescriptions and to identify determinants of empirical antibiotic choices in the emergency department.

Methods

Observational, retrospective, one-year cohort study in hospitalized adults with pneumonia. Antibiotic choices and clinical and demographic data were recorded on a standardized form. Antibiotics with antipseudomonal activity were classified into two groups: a) β-lactam antipseudomonals (β-APS), including carbapenems, piperacillin / tazobactam or cefepime (in monotherapy or combination) and b) monotherapy with antipseudomonal quinolones.

Results

Data were recorded from 549 adults with pneumonia, with Pseudomonas aeruginosa being isolated in only nine (1.6%). Most (85%) prescriptions were compliant with SEPAR guidelines and 207 (37%) patients received antibiotics with antipseudomonal activity (14% β-APS and 23% levofloxacin). The use of β-APS was independently associated with ICU admission (OR 8.16 95% CI 3.69–18.06) and prior hospitalization (OR 6.76 95% CI 3.02–15.15), while levofloxacin was associated with negative pneumococcal urine antigen tests (OR 3.41 95% CI 1.70–6.85) but negatively associated with ICU admission (OR 0.26 95% CI 0.08–0.86). None of these factors were associated with P aeruginosa episodes. In univariate analysis, prior P aeruginosa infection/colonization (2/9 vs 6/372, p = 0.013), severe COPD (3/9 vs 26/372, p = 0.024), multilobar involvement (7/9 vs 119/372, p = 0.007) and prior antibiotic (6/9 vs 109/372, p = 0.025) were significantly associated with P aeruginosa episodes.

Conclusions

Antipseudomonal prescriptions were common, in spite of the very low incidence of Pseudomonas aeruginosa. The rationale for prescription was influenced by both severity-of-illness and pneumococcal urine antigen test (levofloxacin) and prior hospitalization and ICU admission (β-APS). However, these factors were not associated with P aeruginosa episodes. Only prior P aeruginosa infection/colonization and severe COPD seem to be reliable indicators in clinical practice.

Diagnosis and Treatment of Adults with Community-acquired Pneumonia. An Official Clinical Practice Guideline of the American Thoracic Society and Infectious Diseases Society of America

Background: This document provides evidence-based clinical practice guidelines on the management of adult patients with community-acquired pneumonia.

Methods: A multidisciplinary panel conducted pragmatic systematic reviews of the relevant research and applied Grading of Recommendations, Assessment, Development, and Evaluation methodology for clinical recommendations.

Results: The panel addressed 16 specific areas for recommendations spanning questions of diagnostic testing, determination of site of care, selection of initial empiric antibiotic therapy, and subsequent management decisions. Although some recommendations remain unchanged from the 2007 guideline, the availability of results from new therapeutic trials and epidemiological investigations led to revised recommendations for empiric treatment strategies and additional management decisions.

Conclusions: The panel formulated and provided the rationale for recommendations on selected diagnostic and treatment strategies for adult patients with community-acquired pneumonia.

Defining Community-Acquired Pneumonia as a Public Health Threat: Arguments in Favor from Spanish Investigators

Despite advances in its prevention, pneumonia remains associated with high morbidity, mortality, and health costs worldwide. Studies carried out in the last decade have indicated that more patients with community-acquired pneumonia (CAP) now require hospitalization. In addition, pneumonia management poses many challenges, especially due to the increase in the number of elderly patients with multiple comorbidities, antibiotic-resistant pathogens, and the difficulty of rapid diagnosis. In this new call to action, we present a wide-ranging review of the information currently available on CAP and offer some reflections on ways to raise awareness of this disease among the general public. We discuss the burden of CAP and the importance of attaining better, faster microbiological diagnosis and initiating appropriate treatment. We also suggest that closer cooperation between health professionals and the population at large could improve the management of this largely preventable infectious disease that takes many lives each year.

Emerging antibiotics for community-acquired pneumonia

Introduction: Community-acquired pneumonia is the most common infection leading to hospitalization and death in all age groups, especially in elderly populations. Increasing antibiotic resistance among the common bacterial pathogens associated with community-acquired pneumonia, especially Streptococcus pneumoniae and staphylococci, has made its empirical treatment increasingly problematic, highlighting the need for effective antibiotic therapy.Areas covered: We searched PubMed and ClinicalTrials.gov for English-language reports of phase III clinical trials conducted between 2000 and 2019 concerning the antibiotic treatment of community-acquired pneumonia. We provide a summary of the latest approved drugs for this indication and highlight emerging drugs with a potential indication.Expert opinion: Ceftaroline (a new cephalosporine) and omadacycline (a cycline alternative), either parenterally or orally, are the only two new antibiotics to have been approved by the FDA for the treatment of community-acquired pneumonia in the last five years. Among the antimicrobials in development, Lefamulin (the first pleuromutilin), is currently in phase III development. Among the known antibiotic classes, solithromycin (a macrolide), nemonoxacin (a quinolone), and delafloxacin and zabofloxacin (both fluoroquinolones), have been studied in phase II and III in clinical trials. The availability of these new antibiotics may offer opportunities to improve the empirical treatment for community-acquired pneumonia.

PTP1B negatively regulates nitric oxide-mediated Pseudomonas aeruginosa killing by neutrophils

Neutrophils play a critical role in host defense against Pseudomonas aeruginosa infection. Mechanisms underlying the negative regulation of neutrophil function in bacterial clearance remain incompletely defined. Here, we demonstrate that protein tyrosine phosphatase-1B (PTP1B) is a negative regulator of P. aeruginosa clearance by neutrophils. PTP1B-deficient neutrophils display greatly enhanced bacterial phagocytosis and killing, which are accompanied by increased Toll-like receptor 4 (TLR4) signaling activation and nitric oxide (NO) production following P. aeruginosa infection. Interestingly, PTP1B deficiency mainly upregulates the production of IL-6 and IFN-β, leads to enhanced TLR4-dependent STAT1 activation and iNOS expression by neutrophils following P. aeruginosa infection. Further studies reveal that PTP1B and STAT1 are physically associated. These findings demonstrate a negative regulatory mechanism in neutrophil underlying the elimination of P. aeruginosa infection though a PTP1B-STAT1 interaction.

Community-acquired pneumonia as an emergency condition

PURPOSE OF REVIEW

Despite the improvements in its management, community-acquired pneumonia (CAP) still exhibits high global morbidity and mortality rates, especially in elderly patients. This review focuses on the most recent findings on the epidemiology, cause, diagnosis and management of CAP.

RECENT FINDINGS

There is consistent evidence that the trend in CAP mortality has declined over time. However, the mortality of pneumococcal CAP has not changed in the last two decades, with an increase in the rate of hospitalization and more severe forms of CAP. Streptococcus pneumoniae remains the most frequent cause of CAP in all settings, age groups and regardless of comorbidities. However, the implementation of molecular diagnostic tests in the last years has identified respiratory viruses as a common cause of CAP too. The emergency of multidrug-resistance pathogens is a worldwide concern. An improvement in our ability to promptly identify the causative cause of CAP is required in order to provide pathogen-directed antibiotic therapy, improve antibiotic stewardship programs and implement appropriate vaccine strategies.

SUMMARY

It is time to apply all the knowledge generated in the last decade in order to optimize the management of CAP.

Activity of ceftolozane-tazobactam and comparators against Pseudomonas aeruginosa from patients in different risk strata - SMART United States 2016-2017

OBJECTIVES

Infections caused by Pseudomonas aeruginosa are often difficult to treat. Knowledge of the risk of infection with resistant P. aeruginosa would allow more discriminatory prescribing of broad-spectrum antimicrobials. Using clinical isolates collected as part of the Study for Monitoring Antimicrobial Resistance Trends (SMART), we examined the activity of commonly used β-lactams, levofloxacin, and ceftolozane-tazobactam (C/T), an antipseudomonal cephalosporin/β-lactamase inhibitor approved in the United States and over 60 countries worldwide, against P. aeruginosa isolates from patients in different risk strata.

METHODS

In 2016-2017, 25 hospitals in the US each collected up to 250 consecutive gram-negative bacilli per year from respiratory tract (RTI), intraabdominal (IAI), and urinary tract (UTI) infections. MICs of 9,964 isolates (including 1,887 P. aeruginosa) were determined using CLSI broth microdilution and interpreted with CLSI breakpoints.

RESULTS

Susceptibility of all P. aeruginosa isolates combined was 94.7% to C/T and 76.8%, 77.0%, 70.2%, and 69.0% to ceftazidime, meropenem, piperacillin-tazobactam, and levofloxacin, respectively. Susceptibility to the β-lactam comparators was 8-11 percentage points lower among ICU than non-ICU isolates, 7-11 points lower in isolates collected ≥48h than <48h post-admission, 1-5 points lower in patients <65 years of age than older patients, and 3-12 points lower in RTI than IAI and UTI isolates. C/T maintained activity against >90% of P. aeruginosa isolates in all risk strata and against 75-88% of isolates nonsusceptible to ceftazidime, meropenem, or piperacillin-tazobactam.

CONCLUSIONS

C/T represents a promising new treatment option even in strata in which the risk of infection with β-lactam-nonsusceptible P. aeruginosa appeared higher.

Risk factors and the resistance mechanisms involved in Pseudomonas aeruginosa mutation in critically ill patients

Background

The objective of this study was to determine the main risk factors of Pseudomonas aeruginosa mutation as well as the mechanisms of acquired resistance.

Methods

We conducted a 2-year prospective study in patients who were carriers of a Pseudomonas aeruginosa strain and who had been admitted to a medical/surgical ICU.

Results

Of the 153 patients who were included, 34 had a mutation in their strain. In a multivariate analysis, a duration of ventilation > 24 days was a risk factor for mutation (risk ratio 4.29; CI 95% 1.94-9.49) while initial resistance was a protective factor (RR 0.36; CI 95% 0.18-0.71). In a univariate analysis, exposure of P. aeruginosa to ceftazidime was associated with an over-production of AmpC cephalosporinase and exposure to meropenem was associated with impermeability. A segmentation method based on the duration of ventilation (> 24 days), initial resistance, and exposure of strains to ceftazidime made it possible to predict at 83% the occurrence of mutation.

Conclusion

The duration of ventilation and the presence of resistance as soon as P. aeruginosa is identified are predictive factors of mutation in ICU patients.

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.

Multidrug Resistant Gram-Negative Bacteria in Community-Acquired Pneumonia

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2019. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2019. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

A case report of community-acquired Pseudomonas aeruginosa pneumonia complicated with MODS in a previously healthy patient and related literature review

Background

Pseudomonas aeruginosa is an unusual pathogen in community-acquired pneumonia, especially in previously healthy adults, but often indicates poor prognosis.

Case presentation

We report a previously healthy patient who developed severe community-acquired pneumonia (CAP) caused by P. aeruginosa. He deteriorated to septic shock and multiple organ dysfunction syndrome (MODS) quickly, complicated by secondary hematogenous central nervous system (CNS) infection. After 1 month of organ support and antipseudomonal therapy, he had significant symptomatic improvement and was discharged from hospital. During treatment, the pathogen developed resistance to carbapenems quickly and the antibiotic regimen was adjusted accordingly.

Conclusions

According to our case and related literature review, we conclude that more attention should be paid to community-acquired Pseudomonas aeruginosa pneumonia, because of its rapid progression and poor prognosis.

Recommendations and guidelines for the treatment of pneumonia in Taiwan

Pneumonia is a leading cause of death worldwide, ranking third both globally and in Taiwan. This guideline was prepared by the 2017 Guidelines Recommendations for Evidence-based Antimicrobial agents use in Taiwan (GREAT) working group, formed under the auspices of the Infectious Diseases Society of Taiwan (IDST). A consensus meeting was held jointly by the IDST, Taiwan Society of Pulmonary and Critical Care Medicine (TSPCCM), the Medical Foundation in Memory of Dr. Deh-Lin Cheng, the Foundation of Professor Wei-Chuan Hsieh for Infectious Diseases Research and Education and CY Lee's Research Foundation for Pediatric Infectious Diseases and Vaccines. The final guideline was endorsed by the IDST and TSPCCM. The major differences between this guideline and the 2007 version include the following: the use of GRADE methodology for the evaluation of available evidence whenever applicable, the specific inclusion of healthcare-associated pneumonia as a category due to the unique medical system in Taiwan and inclusion of recommendations for treatment of pediatric pneumonia. This guideline includes the epidemiology and recommendations of antimicrobial treatment of community-acquired pneumonia, hospital-acquired pneumonia, ventilator-associated pneumonia, healthcare-associated pneumonia in adults and pediatric pneumonia.

Challenges in severe community-acquired pneumonia: a point-of-view review

Purpose

Severe community-acquired pneumonia (SCAP) is still associated with substantial morbidity and mortality. In this point-of-view review paper, a group of experts discuss the main controversies in SCAP: the role of severity scores to guide patient settings of care and empiric antibiotic therapy; the emergence of pathogens outside the core microorganisms of CAP; viral SCAP; the best empirical treatment; septic shock as the most lethal complication; and the need for new antibiotics.

Methods

For all topics, the authors describe current controversies and evidence and provide recommendations and suggestions for future research. Evidence was based on meta-analyses, most recent RCTs and recent interventional or observational studies. Recommendations were reached by consensus of all the authors.

Results and conclusions

The IDSA/ATS criteria remain the most pragmatic tool to predict ICU admission. The authors recommend a combination of a beta-lactam/beta-lactamase inhibitor or a third G cephalosporin plus a macrolide in most SCAP patients, and to empirically cover PES (P. aeruginosa, extended spectrum beta-lactamase producing Enterobacteriaceae, methicillin-resistant S. aureus) pathogens when at least two specific risk factors are present. In patients with influenza CAP, the authors recommend the use of oseltamivir and avoidance of the use of steroids. Corticosteroids can be used in case of refractory shock and high systemic inflammatory response.

Intra-Vesical Colistin for Pseudomonas aeruginosa Urinary Tract Infections

The numbers of multiple drug-resistant Gram-negative bacterial infections are rising worldwide. The threat is increased by the lack of new antibiotics, so clinicians are turning to older drugs previously abandoned due to their recognized toxicity, such as colistin. However, the need to avoid kidney toxicity from colistin has led to its topical use. We present the case of a patient with type I cardiorenal syndrome with cystitis due to multiple drug-resistant Pseudomonas aeruginosa who was successfully treated with intravesical instillation of colistin.

LEARNING POINTS

The case report is one of the few in the literature on the intravesical instillation of colistin to address lower urinary tract infection.Isolated intravesical colistin instillation was effective in a patient with anuria.

Multidrug Resistant Gram-Negative Bacteria in Community-Acquired Pneumonia

Community-acquired pneumonia (CAP) is associated with high morbidity and mortality worldwide [1]. Although several different bacteria and respiratory viruses can be responsible for CAP, Streptococcus pneumoniae (pneumococcus) remains the most common causative pathogen. A small proportion of CAP cases are caused by Gram-negative bacteria, especially Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumannii and Stenotrophomona maltophilia [2, 3]. The main problem concerning the treatment of Gram-negative bacterial infections is their related antibiotic resistance, reported as multidrug resistant (MDR = resistant to at least one agent in three or more groups of antibiotics), extensively drug resistant (XDR = resistant to at least one agent in all but two or fewer groups of antibiotics) and pan-drug resistant (PDR = resistant to all groups of antibiotics) [4]. This makes the clinical management of pneumonia caused by such pathogens a challenge for physicians. Taking into account the clinical severity that may be associated with CAP caused by Gram-negative bacteria (respiratory failure, bacteremia, shock, acute respiratory distress syndrome [ARDS]) the magnitude of the global health problem is tremendous.

Ceftobiprole for the treatment of pneumonia

Ceftobiprole is a fifth-generation cephalosporin with potent antimicrobial activity against Gram positive and Gram-negative bacteria. It has been approved in major European countries for the treatment of community-acquired pneumonia (CAP) and hospital-acquired pneumonia (HAP), excluding ventilator-associated pneumonia (VAP). Ceftobiprole is currently in a phase 3 clinical program for registration in the U.S. In 2015, it was designated as an infectious disease product qualified for the treatment of lung and skin infections by the FDA. The efficacy of ceftobiprole in pneumonia has been demonstrated in two-phase III clinical trials conducted in patients with CAP and HAP. The recommended dose in the adult with pneumonia is 500 mg every 8 h infused in 2 h; in case of renal failure, the regimen of administration must be adjusted according to the patient's renal function. It is not necessary to adjust the dose according to gender, age, body weight or liver failure. In case of hyperfiltration, an extension to 4 h infusion of the 500mg TID is required.

Community acquired pneumonia among adult patients at an Egyptian university hospital: bacterial etiology, susceptibility profile and evaluation of the response to initial empiric antibiotic therapy

Background

Effective empirical antibiotic therapy for community acquired pneumonia (CAP), based on frequently updated data about the pattern of bacterial distribution and their antimicrobial susceptibilities, is mandatory.

Aim

To identify the bacterial etiology of CAP in adults and their antibiotic susceptibility patterns and to evaluate the response to initial empirical antibiotic therapy in an Egyptian university hospital.

Settings and design

A cross-sectional hospital-based study.

Patients and methods

CAP cases were selected by systemic random sampling from those admitted to the chest department. All were evaluated at admission and 4 days after starting empiric therapy. Typical bacteria were isolated, identified and tested for their antibiotic susceptibility. An indirect IF assay was used to diagnose atypical bacteria. Clinical response to initial empiric antibiotic therapy was clinically, laboratory and radiologically evaluated.

Results

Two hundred and seventy CAP patients were included. Bacteria represented 50.4% of them. Klebsiella pneumoniae was the most prevalent bacterium (10.37%) followed by Streptococcus pneumoniae and P. aeruginosa (7.78% each). Overall, 76.2% of isolates showed a multidrug resistant phenotype: 82.61% (19/23) S. pneumoniae, 89.66 % (26/29) K. pneumoniae, 65.22% (15/23) Pseudomonas aeruginosa, 87.50% (7/8) Escherichia coli and 81.25 % (13/16) Staphylococcus aureus. Broad spectrum β-lactams, especially carbapenems, and moxifloxacin showed in vitro efficacy on most of the tested isolates. Forty-three cases (15.9%) were nonresponders, 37 (86%) of them showed bacterial etiology. The highest rate of nonresponsiveness (30.43%) was observed in cases receiving antipseudomonal/antipneumococcal β-lactam plus a fluoroquinolone for suspected P. aeruginosa infection.

Conclusion

Multidrug resistance in bacteria causing CAP and high frequency of isolation of hospital pathogens are prominent features of this study. Azithromycin containing regimens were associated with the lowest rates of nonresponsiveness. Development and implementation of an antibiotic stewardship program are highly recommended for CAP management.

Risk factors for hospitalized patients with resistant or multidrug-resistant Pseudomonas aeruginosa infections: a systematic review and meta-analysis

Background

Identifying risk factors predicting acquisition of resistant Pseudomonas aeruginosa will aid surveillance and diagnostic initiatives and can be crucial in early and appropriate antibiotic therapy. We conducted a systematic review examining risk factors of acquisition of resistant P. aeruginosa among hospitalized patients.

Methods

MEDLINE®, EMBASE®, and Cochrane Central were searched between 2000 and 2016 for studies examining independent risk factors associated with acquisition of resistant P. aeruginosa, among hospitalized patients. Random effects model meta-analysis was conducted when at least three or more studies were sufficiently similar.

Results

Of the 54 eligible articles, 28 publications (31studies) examined multi-drug resistant (MDR) or extensively drug resistant (XDR) P. aeruginosa and 26 publications (29 studies) examined resistant P. aeruginosa. The acquisition of MDR P. aeruginosa, as compared with non-MDR P. aeruginosa, was significantly associated with intensive care unit (ICU) admission (3 studies: summary adjusted odds ratio [OR] 2.2) or use of quinolones (4 studies: summary adjusted OR 3.59). Acquisition of MDR or XDR compared with susceptible P. aeruginosa was significantly associated with prior hospital stay (4 studies: summary adjusted OR 1.90), use of quinolones (3 studies: summary adjusted OR 4.34), or use of carbapenems (3 studies: summary adjusted OR 13.68). The acquisition of MDR P. aeruginosa compared with non-P. aeruginosa was significantly associated with prior use of cephalosporins (3 studies: summary adjusted OR 3.96), quinolones (4 studies: summary adjusted OR 2.96), carbapenems (6 studies: summary adjusted OR 2.61), and prior hospital stay (4 studies: summary adjusted OR 1.74). The acquisition of carbapenem-resistant P. aeruginosa compared with susceptible P. aeruginosa, was statistically significantly associated with prior use of piperacillin-tazobactam (3 studies: summary adjusted OR 2.64), vancomycin (3 studies: summary adjusted OR 1.76), and carbapenems (7 studies: summary adjusted OR 4.36).

Conclusions

Prior use of antibiotics and prior hospital or ICU stay was the most significant risk factors for acquisition of resistant P. aeruginosa. These findings provide guidance in identifying patients that may be at an elevated risk for a resistant infection and emphasize the importance of antimicrobial stewardship and infection control in hospitals.