Management and prevention of ventilator-associated pneumonia caused by multidrug-resistant pathogens

Prevalence of Ventilator-Associated Pneumonia in Children Admitted to Pediatric ‎Intensive Care Units in the Middle East: A Systematic Review

Ventilator-associated pneumonia (VAP) is a common healthcare-associated disease in intensive care units, leading to significant morbidity and mortality. This systematic review aims to investigate the prevalence, risk factors, and prevention strategies for VAP in the Middle East. PubMed, SCOPUS, Web of Science, Science Direct, and Google Scholar were systematically searched to include the relevant literature. Rayyan QCRI was used throughout this systematic approach. Ten studies, involving a total of 6295 patients diagnosed with VAP, were included in this review. Among these patients, 336 (5.3%) developed VAP. The prevalence of VAP in children and neonates in the Middle East was relatively low. Risk factors associated with VAP development included prematurity, low birth weight, prolonged mechanical ventilation, enteral feeding, intrusive devices such as umbilical catheters, and cardiac operations. All reviewed studies emphasized the importance of infection control measures in reducing the risk of VAP.

The relationship between renal functions and multi-drug resistant organisms in patients with ventilator-associated pneumonia

Objective: Despite the increase in the frequency of multi-drug resistant organism (MDRO) colonisation and infection in dialysis patients, it is not well known whether the risk of multi-drug resistant (MDR) pneumonia increases in mild-to-severe chronic kidney disease patients not undergoing dialysis. Therefore, we aimed to evaluate the relationship between renal functions and the risk of MDR ventilator-associated pneumonia (VAP) and the specific microbial pattern. Patients and Methods: A total of 133 patients who developed VAP were divided according to their renal function into two groups, an estimated glomerular filtration rate of (eGFR) ≥ 60 mL/ min/1.73 m2 (high eGFR, n=65) and eGFR < 60 mL/min/1.73 m2 (low eGFR, n=68). Results: The low eGFR group presented a significantly high MDRO ratio (p

Colistin conditioning surfaces combined with antimicrobial treatment to prevent ventilator-associated infections

Biofilm formation on endotracheal tubes (ETT) is an important factor in the development of ventilator-associated pneumonia (VAP). This work aimed to investigate the effectiveness of colistin (COL) against the early stages of biofilm formation by Pseudomonas aeruginosa. Two strategies were used: pre-conditioning the adhesion surfaces with COL before biofilm formation and growing biofilms in its presence. The combined effect of treating P. aeruginosa 24-hours old biofilms with Ciprofloxacin (CIP) or colistin (COL) on clean and COL-conditioned surfaces was also assessed. Random deposition of COL residues altered the physico-chemical properties of the adhesion surfaces and impaired biofilm formation. Moreover, as a consequence of the reduced amount of biofilms attached to COL conditioned surfaces, adhered cells became more exposed to the subsequent action of CIP or COL, suggesting a combined outcome of prophylactic and therapeutic COL-based strategies. Results highlighted the promising use of COL to prevent the establishment of biofilms on ETT.

Dosing Colistimethate Every 8 h Results in Higher Plasma Concentrations of Active Colistin Than Every 12-Hourly Dosing without Increase in Nephrotoxicity: A Phase 1 Pharmacokinetics Trial in Healthy Adult Volunteers

Despite its use for decades, pharmacokinetic (PK) and safety studies on colistin are limited. We conducted a phase l, open-label trial to evaluate the safety and PK of multiple doses of intravenous (IV) and aerosolized colistimethate sodium (CMS) administered separately and in combination. In total, 31 healthy adults were enrolled into three cohorts of 9, 10, and 12 participants, respectively. Each cohort received increasing doses of CMS over three dosing periods as follows: Period 1 (IV only), 2.5 mg/kg every 12 h (q12h) to 3.3 mg/kg every 8 h (q8h); Period 2 (aerosolized only), 75 mg 2–4 doses, and Period 3 (combined IV aerosolized), in which was Periods 1 and 2 combined. Safety assessments, serum and lung concentrations of colistin analytes (colistin A, colistin B, CMS A, and CMS B), and kidney biomarkers were measured at specified time points. Increasing the CMS dose from 2.5 mg/kg q12h to q8h resulted in a 33% increase in serum colistin A concentrations from 3.9 μg/mL to 5.3 μg/mL—well above the accepted target of 2 μg/mL for 6 h after dosing, without evidence of nephrotoxicity. However, there was an increase in neurotoxicity, primarily perioral and lingual paresthesias, and self-limited ataxia. IV administration did not increase the lung concentrations of colistin.

Bacterial Patterns and Sensitivity to Antibiotics in Patients Treated with Ventilators at the Intensive Care Unit of Sanglah Hospital Denpasar, Bali, Indonesia

Abstract BACKGROUND: Ventilator use to treat patients with respiratory failure in the Intensive Care Unit (ICU) is crucial to prevent further organ failure caused by inadequate oxygenation. However, as an invasive procedure, the use of a ventilator could lead to nosocomial infection, such as Ventilator-Associated Pneumonia (VAP) caused by opportunistic microorganisms in the ICU. Hence, the author is interested in finding the microbial patterns and its antibiotic sensitivity as a source of data for further researches and providing consideration on antibiotics usage for patients treated with ventilators in the ICU of Sanglah Hospital Denpasar. AIM: This study is conducted to obtain the microbial pattern and antibiotics sensitivity on patients treated with ventilators in the ICU of Sanglah Hospital Denpasar. MATERIALS AND METHODS: This research is based on the cross-sectional descriptive method. Research samples were chosen with consecutive sampling that is included in the research’s inclusion criteria. Patient data were collected from the 1st January 2021 to 30th June 2021 within the ICU of Sanglah Hospital Denpasar. Variables in this research were listed as followed: demographic data of the patients that include age, gender, comorbid, diagnosis, ventilator usage indication, bacterial culture, and bacterial susceptibility test. RESULTS: 185 culture samples were obtained from 113 patients. 18 different species of bacterias were found with the three most common microorganisms being Pseudomonas aeruginosa (22.2%), Acinetobacter baumanii (20%), and Klebsiella pneumoniae (17.3%). Susceptibility pattern found as follows: The prevalence of P aeruginosa was found sensitive towards ceftazidime (68,3%), gentamicin (68,3%), and amikacin (65,9%), A. Baumanii are mostly sensitive to amikacin (56,8%), gentamicin (32,4%), and tigecyline (32,4%), K. Pneumoniae are mostly sensitive to amikacin (83,9%), meropenem (77,4%), and piperacillin/tazobactam (54,8%). Resistance pattern found as follows: The prevalence of P aeruginosa was found resistant towards cefixime (70,7%), cefazolin (58,5%), and cefuroxime (58,5%), A. baumanii are mostly resistant to cefixime (86,5%), cefoperazone (81,1%), and piperacillin/tazobactam (75,7%), K. pneumoniae are mostly resistant to ciprofloxacin (61,3%) and levofloxacin (48,4%). CONCLUSION: To decrease the spreading of multi-drug resistant organisms that have been found in ventilated patients, prevention strategies and rational use of antibiotics needs to be performed correctly. Key-words: Ventilator, microbial pattern, antibiotics, sensitivity, resistance

Therapeutic Antibodies for the Treatment of Respiratory Tract Infections-Current Overview and Perspectives

Respiratorytract infections (RTIs) are frequent and life-threatening diseases, accounting for several millions of deaths worldwide. RTIs implicate microorganisms, including viruses (influenza virus, coronavirus, respiratory syncytial virus (RSV)), bacteria (Pseudomonas aeruginosa, Streptococcus pneumoniae, Staphylococcus aureus and Bacillus anthracis) and fungi (Pneumocystis spp., Aspergillus spp. and very occasionally Candida spp.). The emergence of new pathogens, like the coronavirus SARS-CoV-2, and the substantial increase in drug resistance have highlighted the critical necessity to develop novel anti-infective molecules. In this context, antibodies (Abs) are becoming increasingly important in respiratory medicine and may fulfill the unmet medical needs of RTIs. However, development of Abs for treating infectious diseases is less advanced than for cancer and inflammatory diseases. Currently, only three Abs have been marketed for RTIs, namely, against pulmonary anthrax and RSV infection, while several clinical and preclinical studies are in progress. This article gives an overview of the advances in the use of Abs for the treatment of RTIs, based on the analysis of clinical studies in this field. It describes the Ab structure, function and pharmacokinetics, and discusses the opportunities offered by the various Ab formats, Ab engineering and co-treatment strategies. Including the most recent literature, it finally highlights the strengths, weaknesses and likely future trends of a novel anti-RTI Ab armamentarium.

Multidrug-resistant bacteria in a paediatric palliative care inpatient unit: results of a one year surveillance

Aim: Nosocomial infections (NIs) and multidrug resistant (MDR) pathogens are an important paediatric healthcare issue. In vulnerable patients such as children with life-limiting conditions, MDR infections can be life-threatening. Additionally, these children have a significantly increased risk for colonisation with MDR pathogens. Therefore, it is vital to prevent new colonisations with MDR pathogens in this vulnerable patient group. However, little is known about colonisation with MDR pathogens and NIs in inpatient units for paediatric palliative care (PPC). The aim of this study was to investigate the prevalence of colonisation with MDR pathogens and the incidence of NIs in a PPC unit. Methods: Evaluation of surveillance data of a PPC unit. All patients admitted to a PPC unit from 1^st April 2012 to 31^st March 2013 were screened for MDR pathogens upon admission. Patients who exhibited clinical signs of an infection during their inpatient stay were screened again. Results: During the study period, 198 cases were admitted to the unit. Those cases represent 118 patients. 18% of the patients were colonised with MDR pathogens. The most common MDR pathogens were E. coli (8.1%) and Pseudomonas ssp. (8.1%). In addition, 58% of patients with tracheostomy had MDR pathogens in their tracheal secretions. The incidence density of NIs was 0.99 per 1000 inpatient treatment days with no NI caused by MDR pathogens. Conclusion: Due to a high prevalence, it is reasonable to screen PPC patients for MDR pathogen colonisation before or during admission. Special attention must be given to patients with tracheostomy. Our results provide preliminary evidence that participation in social activities in a PPC unit for patients colonised with MDR pathogens is safe if hygiene concepts are applied.

Predictors and microbiology of ventilator-associated pneumonia among patients with exacerbation of chronic obstructive pulmonary disease

BACKGROUND

Understanding the risk factors and microbiology of ventilator-associated pneumonia (VAP) among patients with chronic obstructive pulmonary disease (COPD) is important for the application of preventive and therapeutic interventions. Therefore, this study was planned to assess the clinical predictors and microbiological features of VAP among COPD patients.

MATERIALS AND METHODS

This prospective study involved patients with exacerbation of COPD who required mechanical ventilation and admitted in respiratory intensive care unit at a tertiary care teaching hospital. Various baseline demographic and clinical features were compared between patients with VAP and without VAP. Univariate and multivariable analyses were done to assess the impact of demographic and clinical features on the development of VAP.

RESULTS

The study included 100 intubated patients with age (mean ± standard deviation [SD]) of 62.45 ± 8.32 years, duration (median) of COPD of 6 years, and Acute Physiology, Age, and Chronic Health Evaluation score (mean ± SD) of 18.60 ± 4.30. In this cohort, 17 patients developed VAP. Multivariable analysis showed that Sequential Organ Failure Assessment (SOFA) score at admission, re-intubation, and history of previous hospitalization were independent predictors of VAP with odds ratio (95% confidence interval) of 2.70 (1.24, 5.63; P = 0.012), 66.96 (4.86, 922.72; P = 0.002), and 35.92 (2.84, 454.63; P = 0.006), respectively. Acinetobacter baumannii was the most frequent organism (n = 8; 47%), followed by Klebsiella pneumoniae (n = 5; 29%), Pseudomonas aeruginosa (n = 1; 6%), and Enterobacter spp. (n = 1; 6%). All organisms were multidrug resistant (MDR).

CONCLUSIONS

SOFA score at admission, re-intubation, and history of previous hospitalization were independent predictors of VAP. Antimicrobial therapy for VAP should cover MDR Gram-negative organisms.

Mechanical Ventilation Impairs IL-17 Cytokine Family Expression in Ventilator-Associated Pneumonia

Mechanical ventilation (MV) is the primary risk factor for the development of ventilator-associated pneumonia (VAP). Besides inducing a pro-inflammatory T-helper (Th)-1 cytokine response, MV also induces an anti-inflammatory Th2 cytokine response, marked by increased IL-4 secretion and reduced bacterial phagocytic capacity of rodent lung macrophages. Since IL-4 is known to downregulate both Th1 and Th17 cytokines, the latter is important in mediating mucosal immunity and combating bacterial and fungal growth, we studied and showed here in a rat model of MV that Th17 cytokines (IL-17A, IL-17F, and IL-22) were significantly upregulated in the lung as a response to different MV strategies currently utilized in clinic. To study whether the increased IL-4 levels are associated with downregulation of the anti-bacterial Th17 cytokines, we subsequently challenged mechanically ventilated rats with an intratracheal inoculation of Pseudomonas aeruginosa (VAP model) and showed a dramatic downregulation of IL-17A, IL-17F, and IL-22, compared to animals receiving the same bacterial burden without MV. For the studied Th1 cytokines (IFNγ, TNFα, IL-6, and IL-1β), only IFNγ showed a significant decrease as a consequence of bacterial infection in mechanically ventilated rats. We further studied IL-17A, the most studied IL-17 family member, in intensive care unit (ICU) pneumonia patients and showed that VAP patients had significantly lower levels of IL-17A in the endotracheal aspirate compared to patients entering ICU with pre-existing pneumonia. These translational data, obtained both in animal models and in humans, suggest that a deficient anti-bacterial Th17 response in the lung during MV is associated with VAP development.

Aerosolized antibiotics for ventilator-associated pneumonia: a pairwise and Bayesian network meta-analysis

Background

Aerosolized antibiotics have been proposed as a novel and promising treatment option for the treatment of ventilator-associated pneumonia (VAP). However, the optimum aerosolized antibiotics for VAP remain uncertain.

Methods

We included studies from two systematic reviews and searched PubMed, EMBASE, and Cochrane databases for other studies. Eligible studies included randomized controlled trials and observational studies. Extracted data were analyzed by pairwise and network meta-analysis.

Results

Eight observational and eight randomized studies were identified for this analysis. By pairwise meta-analysis using intravenous antibiotics as the reference, patients treated with aerosolized antibiotics were associated with significantly higher rates of clinical recovery (risk ratio (RR) 1.21, 95% confidence interval (CI) 1.09–1.34; P = 0.001) and microbiological eradication (RR 1.42, 95% CI 1.22–1.650; P < 0.0001). There were no significant differences in the risks of mortality (RR 0.88, 95% CI 0.74–1.04; P = 0.127) or nephrotoxicity (RR 1.00, 95% CI 0.72–1.39; P = 0.995). Using network meta-analysis, clinical recovery benefits were seen only with aerosolized tobramycin and colistin (especially tobramycin), and microbiological eradication benefits were seen only with colistin. Aerosolized tobramycin was also associated with significantly lower mortality when compared with aerosolized amikacin and colistin and intravenous antibiotics. The assessment of rank probabilities indicated aerosolized tobramycin presented the greatest likelihood of having benefits for clinical recovery and mortality, and aerosolized colistin presented the best benefits for microbiological eradication.

Conclusions

Aerosolized antibiotics appear to be a useful treatment for VAP with respect to clinical recovery and microbiological eradication, and do not increase mortality or nephrotoxicity risks. Our network meta-analysis in patients with VAP suggests that clinical recovery benefits are associated with aerosolized tobramycin and colistin (especially tobramycin), microbiological eradication with aerosolized colistin, and survival with aerosolized tobramycin, mostly based on observational studies. Due to the low levels of evidence, definitive recommendations cannot be made before additional, large randomized studies are carried out.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2106-x) contains supplementary material, which is available to authorized users.

Therapeutic antibodies: A new era in the treatment of respiratory diseases?

Respiratory diseases affect millions of people worldwide, and account for significant levels of disability and mortality. The treatment of lung cancer and asthma with therapeutic antibodies (Abs) is a breakthrough that opens up new paradigms for the management of respiratory diseases. Antibodies are becoming increasingly important in respiratory medicine; dozens of Abs have received marketing approval, and many more are currently in clinical development. Most of these Abs target asthma, lung cancer and respiratory infections, while very few target chronic obstructive pulmonary disease - one of the most common non-communicable causes of death - and idiopathic pulmonary fibrosis. Here, we review Abs approved for or in clinical development for the treatment of respiratory diseases. We notably highlight their molecular mechanisms, strengths, and likely future trends.

RAGE-Mediated Suppression of Interleukin-10 Results in Enhanced Mortality in a Murine Model of Acinetobacter baumannii Sepsis

The receptor for advanced glycation end products (RAGE) is a pattern recognition receptor capable of recognizing multiple pathogen-associated and danger-associated molecular patterns that contributes to the initiation and potentiation of inflammation in many disease processes. During infection, RAGE functions to either exacerbate disease severity or enhance pathogen clearance depending on the pathogen studied. Acinetobacter baumannii is an opportunistic human pathogen capable of causing severe infections, including pneumonia and sepsis, in impaired hosts. The role of RAGE signaling in response to opportunistic bacterial infections is largely unknown. In murine models of A. baumannii pneumonia, RAGE signaling alters neither inflammation nor bacterial clearance. In contrast, RAGE^-/- mice systemically infected with A. baumannii exhibit increased survival and reduced bacterial burdens in the liver and spleen. The increased survival of RAGE^-/- mice is associated with increased circulating levels of the anti-inflammatory cytokine interleukin-10 (IL-10). Neutralization of IL-10 in RAGE^-/- mice results in decreased survival during systemic A. baumannii infection that mirrors that of wild-type (WT) mice, and exogenous IL-10 administration to WT mice enhances survival in this model. These findings demonstrate the role for RAGE-dependent IL-10 suppression as a key modulator of mortality from Gram-negative sepsis.

Empiric Antibiotic Therapy of Nosocomial Bacterial Infections

Broad-spectrum antibiotics are commonly used by physicians to treat various infections. The source of infection and causative organisms are not always apparent during the initial evaluation of the patient, and antibiotics are often given empirically to patients with suspected sepsis. Fear of attempting cephalosporins and carbapenems in penicillin-allergic septic patients may result in significant decrease in the spectrum of antimicrobial coverage. Empiric antibiotic therapy should sufficiently cover all the suspected pathogens, guided by the bacteriologic susceptibilities of the medical center. It is important to understand the major pharmacokinetic properties of antibacterial agents for proper use and to minimize the development of resistance. In several septic patients, negative cultures do not exclude active infection and positive cultures may not represent the actual infection. This article will review the important differences in the spectrum of commonly used antibiotics for nosocomial bacterial infections with a particular emphasis on culture-negative sepsis and colonization.

Incidence, bacteriology, and clinical outcome of ventilator-associated pneumonia at tertiary care hospital

Background:

Ventilator-associated pneumonia (VAP) is the most frequent Intensive Care Unit acquired infection.

Aims:

The aim is to determine the incidence, bacteriology and factors affecting VAP and to determine the multi-drug resistant (MDR) pathogens.

Settings and Design:

This was a prospective observational study conducted over a period of 1 year from April 1, 2011, to March 31, 2012.

Materials and Methods:

The patients fulfilling criteria of VAP were included in this study.

Statistical Analysis:

This was performed using SPSS trial version 11.0 software (SPSS Inc., Chicago, Illinois, USA) and the values of P < 0.05 were considered statistically significant.

Results:

Totally 74 (27.71%) patients were developed VAP. Of total 74 patients with VAP 53 (71.62%) were females and 21 (28.37%) were females (P < 0.0001). Total 13 (17.56%) patients had early-onset VAP and 61 (82.43%) had late-onset VAP (P < 0.0001). The overall incidence of VAP rate per 1000 ventilator days was 39.59. Total 126 bacterial isolates found in 74 patients with VAP. Predominant isolates were Gram-negative 52 (70.27%). Total 41 (55.40%) patients had polymicrobial VAP, and 33 (44.59%) had single isolate. Total 55 (43.65%) isolates were MDR organisms. Total 22 patients with VAP succumbed during treatment with overall case fatality rate of 29.72%. Of total 55 MDR isolates in VAP, 13 (26.63%) were Klebsiella spp., 11(20%) Pseudomonas aeruginosa, 14 (25.45%) Acinetobacter, 8 (14.54%) Escherichia coli, and 9 (16.36%) coagulase positive Staphylococcus aureus. Total 12 (21.41%) patients succumbed among MDR isolates.

Conclusions:

There was a high incidence of MDR pathogens in late-onset VAP. The Gram-negative organisms Klebsiella, PseudomonasE. coli and Acinetobacter were the most commonly isolated organisms with high mortality rates.

Multidrug-Resistant Gram-Negative Bacilli: Infection Control Implications

Antimicrobial resistance is a common iatrogenic complication of both modern life and medical care. Certain multidrug resistant and extensively drug resistant Gram-negative organisms pose the biggest challenges to health care today, predominantly owing to a lack of therapeutic options. Containing the spread of these organisms is challenging, and in reality, the application of multiple control measures during an evolving outbreak makes it difficult to measure the relative impact of each measure. This article reviews the usefulness of various infection control measures in containing the spread of multidrug-resistant Gram-negative bacilli.

Staphylococcus aureus Alpha-Toxin Is Conserved among Diverse Hospital Respiratory Isolates Collected from a Global Surveillance Study and Is Neutralized by Monoclonal Antibody MEDI4893

Staphylococcus aureus infections lead to an array of illnesses ranging from mild skin infections to serious diseases, such endocarditis, osteomyelitis, and pneumonia. Alpha-toxin (Hla) is a pore-forming toxin, encoded by the hla gene, that is thought to play a key role in S. aureus pathogenesis. A monoclonal antibody targeting Hla, MEDI4893, is in clinical development for the prevention of S. aureus ventilator-associated pneumonia (VAP). The presence of the hla gene and Hla protein in 994 respiratory isolates collected from patients in 34 countries in Asia, Europe, the United States, Latin America, the Middle East, Africa, and Australia was determined. Hla levels were correlated with the geographic location, age of the subject, and length of stay in the hospital. hla gene sequence analysis was performed, and mutations were mapped to the Hla crystal structure. S. aureus supernatants containing Hla variants were tested for susceptibility or resistance to MEDI4893. The hla gene was present and Hla was expressed in 99.0% and 83.2% of the isolates, respectively, regardless of geographic region, hospital locale, or age of the subject. More methicillin-susceptible than methicillin-resistant isolates expressed Hla (86.9% versus 78.8%; P = 0.0007), and S. aureus isolates from pediatric patients expressed the largest amounts of Hla. Fifty-seven different Hla subtypes were identified, and 91% of the isolates encoded an Hla subtype that was neutralized by MED4893. This study demonstrates that Hla is conserved in diverse S. aureus isolates from around the world and is an attractive target for prophylactic monoclonal antibody (MAb) or vaccine development.

Multidrug-Resistant Gram-Negative Bacterial Infections in the Hospital Setting: Overview, Implications for Clinical Practice, and Emerging Treatment Options

The increasing prevalence of infections due to multidrug-resistant (MDR) gram-negative bacteria constitutes a serious threat to global public health due to the limited treatment options available and the historically slow pace of development of new antimicrobial agents. Infections due to MDR strains are associated with increased morbidity and mortality and prolonged hospitalization, which translates to a significant burden on healthcare systems. In particular, MDR strains of Enterobacteriaceae (especially Klebsiella pneumoniae and Escherichia coli), Pseudomonas aeruginosa, and Acinetobacter baumannii have emerged as particularly serious concerns. In the United States, MDR strains of these organisms have been reported from hospitals throughout the country and are not limited to a small subset of hospitals. Factors that have contributed to the persistence and spread of MDR gram-negative bacteria include the following: overuse of existing antimicrobial agents, which has led to the development of adaptive resistance mechanisms by bacteria; a lack of good antimicrobial stewardship such that use of multiple broad-spectrum agents has helped perpetuate the cycle of increasing resistance; and a lack of good infection control practices. The rising prevalence of infections due to MDR gram-negative bacteria presents a significant dilemma in selecting empiric antimicrobial therapy in seriously ill hospitalized patients. A prudent initial strategy is to initiate treatment with a broad-spectrum regimen pending the availability of microbiological results allowing for targeted or narrowing of therapy. Empiric therapy with newer agents that exhibit good activity against MDR gram-negative bacterial strains such as tigecycline, ceftolozane-tazobactam, ceftazidime-avibactam, and others in the development pipeline offer promising alternatives to existing agents.

Treatment of Gram-negative pneumonia in the critical care setting: is the beta-lactam antibiotic backbone broken beyond repair?

Beta-lactam antibiotics form the backbone of treatment for Gram-negative pneumonia in mechanically ventilated patients in the intensive care unit. However, this beta-lactam antibiotic backbone is increasingly under pressure from emerging resistance across all geographical regions, and health-care professionals in many countries are rapidly running out of effective treatment options. Even in regions that currently have only low levels of resistance, the effects of globalization are likely to increase local pressures on the beta-lactam antibiotic backbone in the near future. Therefore, clinicians are increasingly faced with a difficult balancing act: the need to prescribe adequate and appropriate antibiotic therapy while reducing the emergence of resistance and the overuse of antibiotics. In this review, we explore the burden of Gram-negative pneumonia in the critical care setting and the pressure that antibiotic resistance places on current empiric therapy regimens (and the beta-lactam antibiotic backbone) in this patient population. New treatment approaches, such as systemic and inhaled antibiotic alternatives, are on the horizon and are likely to help tackle the rising levels of beta-lactam antibiotic resistance. In the meantime, it is imperative that the beta-lactam antibiotic backbone of currently available antibiotics be supported through stringent antibiotic stewardship programs.

Intravenous combined with aerosolised polymyxin versus intravenous polymyxin alone in the treatment of pneumonia caused by multidrug-resistant pathogens: a systematic review and meta-analysis

Colistin has been used to treat nosocomial pneumonia (NP) caused by multidrug-resistant (MDR) Gram-negative bacteria (GNB) via different administration routes. Whether patients may benefit from aerosolised colistin as adjunctive treatment was contradictory. We aimed to clarify the safety and efficacy of administering aerosolised and intravenous (IV-AS) colistin versus intravenous (IV) colistin alone in patients with NP caused by MDR-GNB. Two reviewers independently evaluated and extracted data from PubMed, EMBASE and Cochrane databases. Primary outcomes were clinical response rate, all-cause mortality (ICU or hospital), microbiological eradication and nephrotoxicity. Pooled odds ratios (ORs) were calculated and significance was determined by the Z test. Nine eligible studies involving 672 participants were included. The overall clinical response rate (improvement and cure) was significantly higher in the IV-AS group than that in the IV group [OR=1.81, 95% confidence interval (CI) 1.30-2.53; P=0.0005]. Patients treated with IV-AS colistin showed a higher rate of pathogen eradication (OR=1.66, 95% CI 1.11-2.49; P=0.01) and lower all-cause mortality compared with IV colistin (OR=0.69, 95% CI 0.50-0.95; P=0.02). Nephrotoxicity did not differ significantly between IV-AS and IV groups (five studies; 383 patients) (OR=1.11, 95% CI 0.69-1.80; P=0.67). These data indicate that IV-AS colistin has additional benefits compared with IV colistin alone. Clinicians should be encouraged to give combined administration routes in critically ill patients with NP caused by MDR-GNB.

Anti-PcrV antibody strategies against virulent Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic bacterial pathogen that causes fatal acute lung infections in critically ill individuals. Its pathogenesis is associated with bacterial virulence conferred by the type III secretion system (TTSS), through which P. aeruginosa causes necrosis of the lung epithelium and disseminates into the circulation, resulting in bacteremia, sepsis, and mortality. TTSS allows P. aeruginosa to directly translocate cytotoxins into eukaryotic cells, inducing cell death. The P. aeruginosa V-antigen PcrV, a homolog of the Yersinia V-antigen LcrV, is an indispensable contributor to TTS toxin translocation. Vaccination against PcrV ensures the survival of challenged mice and decreases lung inflammation and injury. Both the rabbit polyclonal anti-PcrV antibody and the murine monoclonal anti-PcrV antibody, mAb166, inhibit TTS toxin translocation. mAb166 IgG was cloned, and a molecular engineered humanized anti-PcrV IgG antigen-binding fragment, KB001, was developed for clinical use. KB001 is currently undergoing Phase-II clinical trials for ventilator-associated pneumonia in France and chronic pneumonia in cystic fibrosis in USA. In these studies, KB001 has demonstrated its safety, a favorable pharmacokinetic profile, and promising potential as a nonantibiotic strategy to reduce airway inflammation and damage in P. aeruginosa pneumonia.

Antibiotic therapy for ventilator-associated tracheobronchitis: a standard of care to reduce pneumonia, morbidity and costs?

PURPOSE OF REVIEW

The present review draws our attention to ventilator-associated tracheobronchitis (VAT) as a distinct clinical entity that has been associated with progression to ventilator-associated pneumonia (VAP) and worse patient outcomes. In contrast to VAP, which has been extensively investigated for over the past 30 years, most VAT studies have been conducted in the past decade. There are ample data which demonstrate that VAT may progress to VAP, have more ventilator days, and have longer ICU stay that may translate into higher healthcare costs.

RECENT FINDINGS

The article focuses on the diagnostic criteria for VAT, causative agents, and studies analyzing associations between VAT and patient outcomes in relation to early, appropriate intravenous, and/or aerosolized antibiotic therapy. Aerosolized antibiotic treatment delivered by improved device technology is a novel approach that has proved to be effective for the treatment and eradication of multidrug-resistant bacterial pathogens. Aerosolized antibiotics are effective in decreasing the use of systemic antibiotics, reducing bacterial resistance, and may also facilitate clinical resolution of infection.

SUMMARY

Evidence presented in this review supports treatment of VAT with early and appropriate antibiotic therapy as a standard of care to reduce VAP, ventilator days, and duration of ICU stay in high-risk patient population.

Ventilator associated pneumonia in the ICU: where has it gone?

PURPOSE OF REVIEW

To highlight the clinical importance of ventilator-associated pneumonia (VAP) in an era of escalating antimicrobial resistance.

RECENT FINDINGS

VAP continues to be an important infection in the critically ill. The development of rapid microbiologic diagnostics and new antimicrobial agents offer opportunities for improved treatment strategies for VAP balancing the need to treat effectively in a timely manner and antimicrobial stewardship. Additionally, the new surveillance definitions for assessing the quality of care in critically ill patients (ventilator-associated events, ventilator-associated conditions, and infection-related ventilator-associated conditions) do not appear to be adequate surrogates for the identification of VAP.

SUMMARY

Clinicians caring for critically ill patients should be aware of the importance of correctly treating VAP. As new diagnostic technologies and antimicrobials become available for VAP, their incorporation into routine patient management should occur in a way that optimizes patient outcomes wherein minimizing further emergence of antimicrobial resistance.

MEDI4893* Promotes Survival and Extends the Antibiotic Treatment Window in a Staphylococcus aureus Immunocompromised Pneumonia Model

Immunocompromised individuals are at increased risk of Staphylococcus aureus pneumonia. Neutralization of alpha-toxin (AT) with the monoclonal antibody (MAb) MEDI4893* protects normal mice from S. aureus pneumonia; however, the effects of the MAb in immunocompromised mice have not been reported. In this study, passive immunization with MEDI4893* increased survival rates and reduced bacterial numbers in the lungs in an immunocompromised murine S. aureus pneumonia model. Lungs from infected mice exhibited alveolar epithelial damage, protein leakage, and bacterial overgrowth, whereas lungs from mice passively immunized with MEDI4893* retained a healthy architecture, with an intact epithelial barrier. Adjunctive therapy or prophylaxis with a subtherapeutic MEDI4893* dose combined with subtherapeutic doses of vancomycin or linezolid improved survival rates, compared with the monotherapies. Furthermore, coadministration of MEDI4893* with vancomycin or linezolid extended the antibiotic treatment window. These data suggest that MAb-mediated neutralization of AT holds promise in strategies for prevention and adjunctive therapy among immunocompromised patients.

Association between Pseudomonas aeruginosa type III secretion, antibiotic resistance, and clinical outcome: a review

Pseudomonas aeruginosa uses a complex type III secretion system to inject the toxins ExoS, ExoT, ExoU, and ExoY into the cytosol of target eukaryotic cells. This system is regulated by the exoenzyme S regulon and includes the transcriptional activator ExsA. Of the four toxins, ExoU is characterized as the major virulence factor responsible for alveolar epithelial injury in patients with P. aeruginosa pneumonia. Virulent strains of P. aeruginosa possess the exoU gene, whereas non-virulent strains lack this particular gene. The mechanism of virulence for the exoU⁺ genotype relies on the presence of a pathogenic gene cluster (PAPI-2) encoding exoU and its chaperone, spcU. The ExoU toxin has a patatin-like phospholipase domain in its N-terminal, exhibits phospholipase A₂ activity, and requires a eukaryotic cell factor for activation. The C-terminal of ExoU has a ubiquitinylation mechanism of activation. This probably induces a structural change in enzymatic active sites required for phospholipase A₂ activity. In P. aeruginosa clinical isolates, the exoU⁺ genotype correlates with a fluoroquinolone resistance phenotype. Additionally, poor clinical outcomes have been observed in patients with pneumonia caused by exoU⁺-fluoroquinolone-resistant isolates. Therefore, the potential exists to improve clinical outcomes in patients with P. aeruginosa pneumonia by identifying virulent and antimicrobial drug-resistant strains through exoU genotyping or ExoU protein phenotyping or both.

Restoration of lung surfactant protein D by IL-6 protects against secondary pneumonia following hemorrhagic shock

OBJECTIVES

To identify novel approaches to improve innate immunity in the lung following trauma complicated by hemorrhagic shock (T/HS) for prevention of nosocomial pneumonia.

METHODS

We developed a rat model of T/HS followed by Pseudomonas aeruginosa (PA) pneumonia to assess the effect of alveolar epithelial cell (AEC) apoptosis, and its prevention by IL-6, on lung surfactant protein (SP)-D protein levels, lung bacterial burden, and survival from PA pneumonia, as well as to determine whether AEC apoptosis is a consequence of the unfolded protein response (UPR). Lung UPR transcriptome analysis was performed on rats subjected to sham, T/HS, and T/HS plus IL-6 protocols. Group comparisons were performed via Kaplan-Meier or ANOVA.

RESULTS

T/HS decreased lung SP-D by 1.8-fold (p < 0.05), increased PA bacterial burden 9-fold (p < 0.05), and increased PA pneumonia mortality by 80% (p < 0.001). IL-6, when provided at resuscitation, normalized SP-D levels (p < 0.05), decreased PA bacterial burden by 4.8-fold (p < 0.05), and prevented all mortality from PA pneumonia (p < 0.001). The UPR transcriptome was significantly impacted by T/HS; IL-6 treatment normalized the T/HS-induced UPR transcriptome changes (p < 0.05).

CONCLUSIONS

Impaired innate lung defense occurs following T/HS and is mediated, in part, by reduction in SP-D protein levels, which, along with AEC apoptosis, may be mediated by the UPR, and prevented by use of IL-6 as a resuscitation adjuvant.

Aortic valve replacement 10 years after lung transplantation

Age-related native pathologic conditions are an inevitable sequela in long-term survivors of solid organ transplantation. A sexagenarian presented with severe aortic valve stenosis 10 years after lung transplantation (LTx). Despite overwhelming concerns of infection because of long-term immunosuppression and the risk of postoperative deterioration of function in transplanted lungs, an open heart surgical procedure with appropriate perioperative management was undertaken, and a successful aortic valve replacement (AVR) was performed.

Signature motifs identify an Acinetobacter Cif virulence factor with epoxide hydrolase activity

Endocytic recycling of the cystic fibrosis transmembrane conductance regulator (CFTR) is blocked by the CFTR inhibitory factor (Cif). Originally discovered in Pseudomonas aeruginosa, Cif is a secreted epoxide hydrolase that is transcriptionally regulated by CifR, an epoxide-sensitive repressor. In this report, we investigate a homologous protein found in strains of the emerging nosocomial pathogens Acinetobacter nosocomialis and Acinetobacter baumannii ("aCif"). Like Cif, aCif is an epoxide hydrolase that carries an N-terminal secretion signal and can be purified from culture supernatants. When applied directly to polarized airway epithelial cells, mature aCif triggers a reduction in CFTR abundance at the apical membrane. Biochemical and crystallographic studies reveal a dimeric assembly with a stereochemically conserved active site, confirming our motif-based identification of candidate Cif-like pathogenic EH sequences. Furthermore, cif expression is transcriptionally repressed by a CifR homolog ("aCifR") and is induced in the presence of epoxides. Overall, this Acinetobacter protein recapitulates the essential attributes of the Pseudomonas Cif system and thus may facilitate airway colonization in nosocomial lung infections.

Risk factors of ventilator-associated pneumonia in pediatric intensive care unit: a systematic review and meta-analysis

OBJECTIVE

To identify risk factors of ventilator-associated pneumonia (VAP) in pediatric intensive care unit (PICU).

METHODS

PubMed, Ovid, Web of Science, the Cochrane Library and references of retrieved articles were searched without language limitation. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by using both the Mantel-Haenszel fixed-effect and the DerSimonian-Laird random-effects models.

RESULTS

Out of the 205 initially retrieved articles, 9 papers were included. All 4,564 patients were enrolled, including 213 patients with VAP and 4,351 patients without VAP. Among fourteen risk factors, six factors had statistical significances. Risk factors of VAP and its value of OR were as follows: genetic syndrome (OR =2.04; 95% CI: 1.08-3.86), steroids (OR =1.87; 95% CI: 1.07-3.27), reintubation or self-extubation (OR =3.16; 95% CI: 2.10-4.74), bloodstream infection (OR =4.42; 95% CI: 2.12-9.22), prior antibiotic therapy (OR =2.89; 95% CI: 1.41-5.94), bronchoscopy (OR =4.48; 95% CI: 2.31-8.71).

CONCLUSIONS

Special methods of preventions should be taken in the light of risk factors of VAP in PICU so as to decrease the rate.