Hospital-acquired pneumonia: epidemiology, etiology, and treatment

Utility of the Systemic Inflammation Response Index as a Predictor of Pneumonia After Spontaneous Intracerebral Hemorrhage

OBJECTIVE

We sought to determine whether the initial Systemic Inflammatory Response Index (SIRI) was associated with pneumonia after spontaneous intracerebral hemorrhage (SICH) in hospitalized patients.

PATIENTS AND METHODS

Patients with SICH admitted to Taizhou People's Hospital between January 2019 and December 2021 were retrospectively analyzed. Baseline variables were compared between stroke-associated pneumonia (SAP) and non-SAP groups. Multivariable logistic regression analyses were utilized to calculate the relationship between SIRI and SAP risk.

RESULTS

Of 495 patients included in this research, 192 (38.79%) developed SAP ultimately. The SIRI values exhibited the highest area under the curve value for SAP incidence (area under the curve = 0.736, 95% CI: 0.692-0.781), with respective sensitivity and specificity values of 0.646 and 0.749 at the optimal cutoff threshold of 2.53. In multivariate analysis, high SIRI (≥2.53) was a significant independent predictor of post-SICH SAP even after controlling for other possible confounding variables (odds ratio: 5.11, 95% CI: 2.89-9.04, P < 0.001). According to the restricted cubic splines model, SAP risk increases as SIRI increases.

CONCLUSIONS

We observed that SIRI values may offer high diagnostic utility as a predictor of SAP risk among patients with SICH during the early stages of the disease.

Antimicrobial Solutions for Endotracheal Tubes in Prevention of Ventilator-Associated Pneumonia

Ventilator-associated pneumonia is one of the most frequently encountered hospital infections and is an essential issue in the healthcare field. It is usually linked to a high mortality rate and prolonged hospitalization time. There is a lack of treatment, so alternative solutions must be continuously sought. The endotracheal tube is an indwelling device that is a significant culprit for ventilator-associated pneumonia because its surface can be colonized by different types of pathogens, which generate a multispecies biofilm. In the paper, we discuss the definition of ventilator-associated pneumonia, the economic burdens, and its outcomes. Then, we present the latest technological solutions for endotracheal tube surfaces, such as active antimicrobial coatings, passive coatings, and combinatorial methods, with examples from the literature. We end our analysis by identifying the gaps existing in the present research and investigating future possibilities that can decrease ventilator-associated pneumonia cases and improve patient comfort during treatment.

Pseudomonas aeruginosa: Infections, Animal Modeling, and Therapeutics

Pseudomonas aeruginosa is an important Gram-negative opportunistic pathogen which causes many severe acute and chronic infections with high morbidity, and mortality rates as high as 40%. What makes P. aeruginosa a particularly challenging pathogen is its high intrinsic and acquired resistance to many of the available antibiotics. In this review, we review the important acute and chronic infections caused by this pathogen. We next discuss various animal models which have been developed to evaluate P. aeruginosa pathogenesis and assess therapeutics against this pathogen. Next, we review current treatments (antibiotics and vaccines) and provide an overview of their efficacies and their limitations. Finally, we highlight exciting literature on novel antibiotic-free strategies to control P. aeruginosa infections.

Nasal High Flow Versus Conventional Oxygen Therapy for Postoperative Cardiothoracic Surgery Patients

BACKGROUND

Reintubation and complications in postoperative cardiothoracic patients remain high despite medical advancements. A 2-year retrospective, observational study was conducted in postextubated cardiothoracic patients to assess the effectiveness of the current standard-conventional oxygen therapy (COT) compared with a nasal high flow (NHF) therapy.

OBJECTIVES

The objective of this study was to understand whether NHF therapy would reduce the need for reintubation and improve clinical outcomes after surgery.

METHOD

All consecutive postoperative patients who had same-day elective cardiothoracic surgery in a tertiary hospital were included. The 2013 data were from patients' charts who received COT, and the 2014 data were from patients' charts after the implementation of NHF therapy post extubation as a standard of care.

RESULTS

A total of 400 patient charts were analyzed: 221 and 179 patients in the COT and NHF, respectively. No significant difference was seen in the frequency of reintubation (P = .48). Despite both cohorts having the same length of stay (P = .10), patients treated with NHF required less time on supplemental oxygen (P = .001). Day 1 postoperative chest x-ray results did not show any significant differences between groups, whereas day 2 x-rays showed worsening results in the COT cohort (P < .001). Furthermore, the incidence of ventilator-associated pneumonia (VAP) post extubation was significantly higher in the COT cohort, with zero VAP episodes reported in the NHF cohort (P = .02).

DISCUSSION

Although this study was not able to demonstrate the reduction in reintubation between groups, the use of NHF compared with COT seems to reduce the time spent on oxygen therapy and decrease the rate of VAP. Further evidence including randomized controlled trials is required to determine the impact of NHF on reintubation and complications in postoperative cardiothoracic surgery.

One-year survey of opportunistic premise plumbing pathogens and free-living amoebae in the tap-water of one northern city of China

In this study, qPCR was used to quantify opportunistic premise plumbing pathogens (OPPPs) and free-living amoebae in 11 tap water samples collected over four seasons from a city in northern China. Results demonstrated that the average numbers of gene copies of Legionella spp. and Mycobacterium spp. were significantly higher than those of Aeromonas spp. (p < 0.05). Legionella spp. and Mycobacterium spp. were 100% (44/44) positively detected while P. aeruginosa and Aeromonas spp. were 79.54% (35/44) and 77.27% (34/44) positively detected. Legionella pneumophila was only detected in 4 samples (4/44), demonstrating its occasional occurrence. No Mycobacterium avium or Naegleria fowleri was detected in any of the samples. The average gene copy numbers of target OPPPs were the highest in summer, suggesting seasonal prevalence of OPPPs. Average gene copy numbers of OPPPs in the taps of low-use-frequency were higher than in taps of high-use-frequency, but the difference was not significant for some OPPPs (p > 0.05). Moderate negative correlations between the chlorine concentration and the gene copy numbers of OPPPs were observed by Spearman analysis (r_s ranged from -0.311 to -0.710, p < 0.05). However, no significant correlations existed between OPPPs and AOC, BDOC, or turbidity. Moderate positive correlations were observed between the target microorganisms, especially for Acanthamoeba spp., through Spearman analysis (p < 0.05). Based on our studies, it is proposed that disinfectant concentration, season, taps with different-use frequency, OPPP species, and potential microbial correlations should be considered for control of OPPPs in tap water.

Health care-associated infections - an overview

Health care-associated infections (HCAIs) are infections that occur while receiving health care, developed in a hospital or other health care facility that first appear 48 hours or more after hospital admission, or within 30 days after having received health care. Multiple studies indicate that the common types of adverse events affecting hospitalized patients are adverse drug events, HCAIs, and surgical complications. The US Center for Disease Control and Prevention identifies that nearly 1.7 million hospitalized patients annually acquire HCAIs while being treated for other health issues and that more than 98,000 patients (one in 17) die due to these. Several studies suggest that simple infection-control procedures such as cleaning hands with an alcohol-based hand rub can help prevent HCAIs and save lives, reduce morbidity, and minimize health care costs. Routine educational interventions for health care professionals can help change their hand-washing practices to prevent the spread of infection. In support of this, the WHO has produced guidelines to promote hand-washing practices among member countries.

Frequency of post-stroke pneumonia: Systematic review and meta-analysis of observational studies

Background

Post-stroke pneumonia and other infectious complications are serious conditions whose frequency varies widely across studies.

Aims

We conducted a systematic review to estimate the frequency of post-stroke pneumonia and other types of major infection.

Summary of review

MEDLINE, EMBASE, CINAHL, and PsycINFO databases were searched for prospective studies with consecutive recruitment of stroke patients. The primary outcome was post-stroke pneumonia. Secondary outcomes were any infection and urinary tract infection. Quality assessment was done using Newcastle Ottawa scale. Heterogeneity of estimates across study populations was calculated using Cochran's Q (heterogeneity χ2) and I2 statistics. A total of 47 studies (139,432 patients) with 48 sample populations were eligible for inclusion. Mean age of patients was 68.3 years and their mean National Institute of Health Stroke Scale score was 8.2. The pooled frequency of post-stroke pneumonia was 12.3% (95% confidence interval [CI] 11%–13.6%; I2 = 98%). The pooled frequency from 2011 to 2017 was 13.5% (95% CI 11.8%–15.3%; I2 = 98%) and comparable with earlier periods (P interaction = 0.31). The pooled frequency in studies in stroke units was 8% (95% CI 7.1%–9%; I2 = 78%) and significantly lower than other locations (P interaction = 0.001). The pooled frequency of post-stroke infection was 21% (95% CI 13%–29.3%; I2 = 99%) and of post-stroke urinary tract infection was 7.9% (95% CI 6.7%–9.3%; I2 = 96%).

Conclusion

Approximately 1 in 10 stroke patients experience pneumonia during the acute period of hospital care. The frequency of post-stroke pneumonia has remained stable in recent decades but is lower in patients receiving stroke unit care compared to management in other ward settings.

Pulmonary Infections: Pneumonia

The different appearances of pneumonia such as ill-defined nodules, ground-glass opacities, and consolidations can be easily detected and differentiated with MRI. Since very small nodules and calcifications are extremely challenging due to rather thick slices and loss of signal, MRI is highly recommended as a follow-up tool, to avoid repetitive investigations using ionizing radiation. With the sensitivity of T2-weighted sequences and the potential of contrast-enhanced T1-weighted sequences, important differential diagnostic considerations can be provided. Additionally, developing complications, such as pericardial or pleural effusions, empyema or lung abscess, are easily recognized. Current and future studies are to demonstrate that MRI is well suited as a monitoring and follow-up tool during and after therapy and compares favorably with CT or other imaging methods regarding sensitivity and specificity.

Atrial Fibrillation Is an Independent Risk Factor for Hospital-Acquired Pneumonia

BACKGROUND

Patients who were hospitalized for community-based pneumonia frequently had pre-existing atrial fibrillation (AF) and had subsequent cardiovascular complications. Whether patients who had AF would be susceptible to the development of hospital-acquired pneumonia (HAP) is a serious concern but this has not been investigated. In our clinics, we have made empirical observation of such susceptibility.

OBJECTIVES

To investigate the association between newly developed HAP and pre-existing AF, and to identify whether AF is an independent risk factor for HAP.

METHODS

Hospital data from 8657 sequentially admitted inpatients [1059 patients with AF and 7598 without AF (NAF)] were collected from the Department of Cardiology, First Affiliated Hospital of Shantou University Medical College, Shantou, China, from January 1, 2009 to December 31, 2011. Exclusion criteria were: having previous or current pneumonia, pacemakers, sick sinus syndrome and repeated hospitalization. The incidence of HAP (within 48 hours after hospitalization) was identified among all the patients.

RESULTS

Among the AF patients, 274 had HAP (adjusted rate 25.64%) which was significantly higher than the 276 NAF patients who had HAP (adjusted rate 3.66%; P<0.001). The increased risk was also associated with high blood pressure, heart failure and age, but not with gender, smoking, coronary heart disease, diabetes, congenital heart disease. In addition, our multiple regression analysis indicates that AF is an independent risk factor for HAP.

CONCLUSION

We have identified, for the first time, that AF is an important risk factor for HAP. Although additional clinical confirmation is needed, our data provide valuable evidence for use in prevention of HAP which is the most common cause of death from nosocomial infection.

Ventilator-associated events prevention, learning lessons from the past: A systematic review

BACKGROUND

Preventing Ventilator-associated events (VAE) is a major challenge. Strictly monitoring for ventilator-associated pneumonia (VAP) is not sufficient to ensure positive outcomes. Therefore, the surveillance definition was updated and a change to the broader VAE was advocated.

OBJECTIVE

This paper summarizes the scientific efforts assessing VAP preventive bundles and the recent transition in surveillance methods.

METHODS

We conducted a systematic review to identify lessons from past clinical studies assessing VAP prevention bundles. We then performed a thorough literature review on the recent VAE surveillance algorithm, highlighting its advantages and limitations.

CONCLUSION

VAP prevention bundles have historically proven their efficacy and the introduction of the new VAE definition aimed at refining and objectivizing surveillance methods. Randomized controlled trials remain vital to determine the effect of VAE prevention on patient outcomes. We recommend expanding beyond limited VAP prevention strategies towards VAE prevention bundles.

Vaccines for Pseudomonas aeruginosa: a long and winding road

Despite the recognition of Pseudomonas aeruginosa as an opportunistic pathogen, no vaccine against this bacteria has come to market. This review describes the current state-of-the-art in vaccinology for this bacterium. This includes a discussion of those at risk for infection, the types of vaccines and the approaches for empirical and targeted antigen selection under development, as well as a perspective on where the field should go. In addition, the challenges in developing a vaccine for those individuals at risk are discussed.

In-patient rehabilitation outcomes following lower extremity fracture in patients with pneumonia

BACKGROUND

Pneumonia is a common comorbidity among hospitalized older adults and may impede functional restoration and increase medical cost. Medicare reimbursement rates for patients receiving in-patient medical rehabilitation services are higher for individuals who have comorbid pneumonia. We examined the impact of comorbid pneumonia on outcomes for patients with lower extremity fracture receiving in-patient medical rehabilitation services.

METHODS

Secondary data analysis of medical records obtained from 919 in-patient rehabilitation facilities in the United States. The sample included 153,241 subjects who received in-patient rehabilitation services following lower extremity fracture in 2005-2007. We used multivariable linear regression to evaluate the independent effects of pneumonia on stay and discharge functional status (Functional Independence Measure instrument), and logistic regression models to explore discharge to home versus not home.

RESULTS

Pneumonia was a comorbidity for 4,265 (2.8%) of the subjects with lower extremity fracture. The multivariable models indicated that subjects with no payment-eligible comorbidity experienced shorter stay (regression coefficient -0.44, 95% CI -0.60 to -0.28 d), higher discharge functional status ratings (regression coefficient 1.84, 95% CI 1.42-2.25 points), and higher odds of home discharge (odds ratio 1.19, 95% CI 1.09-1.29), compared to subjects with pneumonia.

CONCLUSIONS

Our findings suggest that comorbid pneumonia is associated with poorer rehabilitation outcomes (stay, discharge functional status, and discharge setting) among subjects receiving in-patient rehabilitation services for lower extremity fracture.

Meropenem Monotherapy for the Treatment of Hospital- Acquired Pneumonia: Results of a Multicenter Trial

The efficacy and tolerability of meropenem as empirical treatment in patients with hospital-acquired pneumonia was determined in a prospective, open-label, non-randomized trial. Patients from 28 centers in the USA received meropenem 1 g every 8 h intravenously. Of 255 patients enrolled, 111 were evaluable for efficacy, including 60 patients with ventilator-associated pneumonia. At end of treatment 74% of patients had a satisfactory clinical response and 64% had this response at follow-up, which could last up to 28 days after treatment. In patients with ventilator-associated pneumonia, a satisfactory clinical response was observed in 68% at the end of treatment and 63% at follow-up. The overall satisfactory response rate for individual pretreatment pathogens ranged from 65% to 100%. This study demonstrates that meropenem monotherapy is effective and well tolerated for patients with hospital-acquired pneumonia, including a subgroup of patients with ventilator-associated pneumonia.

Ventilator-associated pneumonia: a review

Ventilator-associated pneumonia (VAP) is the most common infection seen in intensive care units (ICUs); it accounts for one-fourth of the infections occurring in critically ill patients and is the reason for half of antibiotic prescriptions in mechanically ventilated patients. In addition to being a financial burden on ICUs, it continues to contribute significantly to the morbidity and mortality of ICU patients, with an estimated attributable mortality rate of 8% to 15%. While the pathophysiology of VAP remains relatively unchanged, diagnostic techniques and preventive measures are constantly evolving. The focus of this article is on recent trends in VAP epidemiology, modifiable risk factors, diagnostic techniques, challenges in management, and current data on the prevention of VAP. Important messages that the reader should take away include: 1) There is no gold standard for the diagnosis of VAP; whenever VAP is suspected, if feasible, a quantitative culture should be obtained by invasive or noninvasive methods (whichever is more readily available before initiation of antibiotics); 2) Suspicion based on clinical features should prompt the initiation of a broad spectrum of antibiotics depending on suspected pathogens; 3) Close attention should be paid to de-escalation of antibiotics once microbiological results become available or as the patient starts responding clinically; the ideal duration of treatment should be 8 days instead of the conventional 10 to 14 days, except in situations where Pseudomonas may be suspected or the patient's comorbidities dictate otherwise; and 4) Prevention remains the key to reducing the burden of VAP. We promote the proven preventive measures of using noninvasive ventilation when possible, semirecumbent patient positioning, continuous aspiration of subglottic secretions, and oral chlorhexidine washes along with stress ulcer prophylaxis only after careful assessment of the risks versus benefits.

Long term sequelae from childhood pneumonia; systematic review and meta-analysis

Background

The risks of long term sequelae from childhood pneumonia have not been systematically assessed. The aims of this study were to: (i) estimate the risks of respiratory sequelae after pneumonia in children under five years; (ii) estimate the distribution of the different types of respiratory sequelae; and (iii) compare sequelae risk by hospitalisation status and pathogen.

Methods

We systematically reviewed published papers from 1970 to 2011. Standard global burden of disease categories (restrictive lung disease, obstructive lung disease, bronchiectasis) were labelled as major sequelae. ‘Minor’ sequelae (chronic bronchitis, asthma, other abnormal pulmonary function, other respiratory disease), and multiple impairments were also included. Thirteen papers were selected for inclusion. Synthesis was by random effects meta-analysis and meta-regression.

Results

Risk of at least one major sequelae was 5.5% (95% confidence interval [95% CI] 2.8–8.3%) in non hospitalised children and 13.6% [6.2–21.1%]) in hospitalised children. Adenovirus pneumonia was associated with the highest sequelae risk (54.8% [39.2–70.5%]) but children hospitalised with no pathogen isolated also had high risk (17.6% [10.9–24.3%]). The most common type of major sequela was restrictive lung disease (5.4% [2.5–10.2%]) . Potential confounders such as loss to follow up and median age at infection were not associated with sequelae risk in the final models.

Conclusions

All children with pneumonia diagnosed by a health professional should be considered at risk of long term sequelae. Evaluation of childhood pneumonia interventions should include potential impact on long term respiratory sequelae.

Alcohol-based hand rub and ventilator-associated pneumonia after elective neurosurgery: An interventional study

Background:

Interventional studies on the effect of alcohol-based hand rub on ventilator-associated pneumonia (VAP) among neurosurgical patients are scarce.

Aim:

To observe the effect of alcohol-based hand rub on tracheobronchial colonization and VAP after elective neurosurgical procedures.

Materials and Methods:

An interventional study using a “before–after” design in a tertiary care center in Kerala. Two 9-month study periods were compared; between these periods, an infection control protocol incorporating an alcohol-based hand rub was implemented for a period of 3 months and continued thereafter. Consecutive patients who required mechanical ventilation after neurosurgery between January and September 2006 and 2007, respectively, were included. Outcome measures included VAP rate, tracheobronchial colonization rate, profile of microorganisms and patient survival.

Results:

A total of 352 patients were on mechanical ventilator for a varying period of 1–125 days. The patients in the control and intervention groups were similar with regard to sex, age and type of neurosurgery. Tracheobronchial colonization was seen in 86 (48.6%) of 177 in the control group and 73 (41.7%) of 175 among the intervention group (P = 0.195). The VAP rates in the control and intervention groups were 14.03 and 6.48 per 1000 ventilator days (P = 0.08). The predominant organisms causing VAP and tracheobronchial colonization were Klebsiella and Pseudomonas aeruginosa, respectively, in both groups. Patient survival rates were 87.6% (control) and 92% (intervention).

Conclusion:

Clinical results indicated a better outcome, showing a reduction in tracheobronchial colonization rate and VAP rate, although this was not statistically significant.

Appropriateness is critical

Inappropriate empirical antibiotic therapy for severe infections in the intensive care unit is a modifiable prognostic factor that has a great effect on patient outcome and health care resources. Inappropriate treatment is usually associated with microorganisms resistant to the common antibiotics, which must be empirically targeted when risk factors are present. Previous antibiotic exposure, prolonged length of hospital stay, admission category, local susceptibilities, colonization pressure, and the presence of invasive devices increase the likelihood of infection by resistant pathogens. Consideration of issues beyond in vitro susceptibility, such as antibiotic physicochemistry, tissue penetration, and pharmacokinetic/pharmacodynamic-driven dosing, is mandatory for the optimization of antibiotic use.

Pseudomonas aeruginosa: host defence in lung diseases

Lung infections caused by the opportunistic pathogen Pseudomonas aeruginosa can present as a spectrum of clinical entities from a rapidly fatal pneumonia in a neutropenic patient to a multi-decade bronchitis in patients with cystic fibrosis. P. aeruginosa is ubiquitous in our environment, and one of the most versatile pathogens studied, capable of infecting a number of diverse life forms and surviving harsh environmental factors. It is also able to quickly adapt to new environments, including the lung, where it orchestrates virulence factors to acquire necessary nutrients, and if necessary, turn them off to prevent immune recognition. Despite these capabilities, P. aeruginosa rarely infects healthy human lungs. This is secondary to a highly evolved host defence mechanism that efficiently removes inhaled or aspirated pseudomonads. Many arms of the respiratory host defence have been elucidated using P. aeruginosa as a model pathogen. Human infections with P. aeruginosa have demonstrated the importance of the mechanical barrier functions including mucus clearance, and the innate immune system, including the critical role of the neutrophilic response. As more models of persistent or biofilm P. aeruginosa infections are developed, the role of the adaptive immune response will likely become more evident. Understanding the pathogenesis of P. aeruginosa, and the respiratory host defence response to it has, and will continue to, lead to novel therapeutic strategies to help patients.

Pulmonary Infections – Pneumonia

The different appearances of pneumonia such as ill-defined nodules, ground-glass opacities, and consolidations can be easily detected and differentiated with MRI. Since very small nodules and calcifications are extremely challenging due to rather thick slices and loss of signal, MRI is highly recommended as a follow-up tool, to avoid repetitive investigations using ionizing radiation. With the sensitivity of T2-weighted sequences and the potential of contrast-enhanced T1-weighted sequences important differential diagnostic considerations can be provided. Additionally, developing complications, such as pericardial or pleural effusions, empyema or lung abscess, are easily recognized. Current and future studies are to demonstrate that MRI is well suited as a monitoring and follow-up tool during and after therapy and compares favorably with CT or other imaging methods regarding sensitivity and specificity.

Duration of antibiotic therapy for ventilator-associated pneumonia caused by non-fermentative gram-negative bacilli

BACKGROUND AND PURPOSE

Chastre et al. compared eight and 15 days of antibiotic therapy for ventilator-associated pneumonia (VAP), finding no difference in outcome with the exception of VAP caused by non-fermentative gram-negative bacilli (NFGNB), for which a higher recurrence rate was seen in the shorter-duration group (JAMA 2003;290:2588-2598). We recently examined our institutional experience with VAP caused by NFGNB to determine whether shorter courses of antibiotic therapy were associated with higher rates of recurrence.

METHODS

Data collected on all patients completing treatment for VAP in a surgical/trauma intensive care unit from December 1996 to October 2004 were analyzed retrospectively for the relations between the duration of antibiotic therapy and recurrence and in-hospital mortality rates.

RESULTS

Of the 452 episodes of VAP, 154 were associated with NFGNB. Twenty-seven patients were treated with 3-8 days (mean 6.4 +/- 0.3 days) of antibiotics, whereas 127 received nine or more days (mean 17.1 +/- 0.7 days) of therapy. The recurrence rate for infections treated with the shorter course was 22% vs. 34% for patients receiving nine or more days of antibiotics (p = 0.27). The mortality rates were 22% and 14%, respectively (p = 0.38). Similar trends were demonstrated for infections caused by other organisms.

CONCLUSIONS

We did not find a higher recurrence rate in patients with VAP caused by NFGNB who received shorter courses of antibiotic therapy. On the contrary, those patients receiving shorter courses trended toward lower rates of recurrence. Pending further prospective trials addressing the duration of antibiotic treatment for patients with VAP caused by NFGNB, shorter courses of treatment, perhaps based on improvement in clinical parameters, may be warranted.

Chromosomalgfplabelling ofPseudomonas aeruginosausing a mini-Tn7transposon: application for studies of bacteria–host interactions

Analysis of bacterial interactions with host cells using multiple techniques is essential for studies on microbial pathogenesis and for the development of new antimicrobial therapies. Pseudomonas aeruginosa is an important opportunistic pathogen that can cause severe, often life-threatening pulmonary infections in individuals with impaired host defense mechanisms. Using a mini-Tn7 transposon delivery system, we have chromosomally labelled the strain P. aeruginosa PAK with a green fluorescent protein gene (gfp) and tested PAKgfp as a research tool for studies of bacteria–host interactions. We were able to reliably and rapidly measure the interactions of PAKgfp with A549 human lung epithelial cells by using flow cytometry, a fluorometric microplate reader-based assay, and fluorescence microscopy. With these analytical tools, we have demonstrated the adhesion of PAKgfp to the extracellular matrix protein fibronectin and the involvement of fibronectin in PAKgfp–A549 cell interactions. PAKgfp can be successfully used to explore the effects of various pharmacological compounds on P. aeruginosa – host cell interactions in both in vitro and in vivo systems, with potentially important medical applications.

Ventilator-associated pneumonia: diagnosis, treatment, and prevention

While critically ill patients experience a life-threatening illness, they commonly contract ventilator-associated pneumonia. This nosocomial infection increases morbidity and likely mortality as well as the cost of health care. This article reviews the literature with regard to diagnosis, treatment, and prevention. It provides conclusions that can be implemented in practice as well as an algorithm for the bedside clinician and also focuses on the controversies with regard to diagnostic tools and approaches, treatment plans, and prevention strategies.

Predictors of long-term mortality in patients with ventilator-associated pneumonia

PURPOSE

To determine the long-term outcome of ventilator-associated pneumonia (VAP) and identify factors associated with increased mortality.

METHODS

We retrospectively studied 671 patients with VAP admitted to an intensive care unit between 1994 and 2000. We determined long-term and out-of-hospital mortality for these patients.

RESULTS

The in-hospital mortality was 42.3%; 19.8% of patients had concomitant bacteremia, the mortality was 59.7% versus 38.0% for those without bacteremia (P <.001). The factors associated with increased hospital mortality by univariable analysis were: diagnosis on admission, the need of vasopressors during the stay in the intensive care unit, not undergoing a tracheostomy, the absence of fever, the presence of concomitant bacteremia, and renal failure or the need for dialysis. Patients transferred from an outside hospital and patients with normal serum bicarbonate, serum total bilirubin <2 mg/dL, and platelets >120x4> 10(3)/microL had a lower in-hospital mortality. All of these factors except bilirubin level, platelet count, transfer from outside hospital, and serum bicarbonate remained significant on multivariable analysis. The estimated mortality at 1, 3 and 5 years is 25.9% (95% confidence interval [CI], 20.2-30.1%), 33.6% (95% CI, 27.4-39.2%) and 44.7% (95% CI, 38.1-50.6%), respectively.

CONCLUSIONS

VAP is associated with a high rate of hospital and long-term mortality. The presence of bacteremia is associated with a high mortality. The 5-year estimated mortality of the survivors is less than 50%.

Prevalência e prognóstico dos pacientes com pneumonia associada à ventilação mecânica em um hospital universitário

OBJETIVO: Determinar prevalência de pneumonia associada à ventilação mecânica em unidade de terapia intensiva, fatores associados e evolução. MÉTODOS: Foram avaliados 278 pacientes sob ventilação mecânica por mais de 24 horas prospectivamente em hospital universitário. RESULTADOS: Desenvolveram a doença 38,1% dos pacientes, 35,7 casos/1.000 dias de ventilação mecânica: 45,3% por bacilos gram negativos, Pseudomonas aeruginosa (22%) o mais comum e 43,4% por germes multi-resistentes. O grupo com pneumonia associada à ventilação mecânica teve maiores tempos de ventilação mecânica, desmame, permanência no hospital e na unidade de terapia intensiva (p < 0,001); atelectasia, síndrome do desconforto respiratório agudo, pneumotórax, sinusite, traqueobronquite e infecção multirresistente foram mais comuns (p < 0,05). Letalidades na unidade de terapia intensiva e no hospital foram semelhantes. Fatores associados à doença (razão de chances; intervalo de confiança 95%): sinusite aguda (38,8; 3,4 - 441), ventilação mecânica >10 dias (7,7; 4,1 - 14,2), imunodepressão (4,3; 1,3 - 14,3), síndrome do desconforto respiratório agudo (3,5; 1,4 - 9,0), atelectasia (3,0; 1,2 - 7,3), parada cardiorrespiratória (0,18; 0,05 - 0,66) e hemorragia digestiva alta (0,07; 0,009 - 0,62]. Fatores associados ao óbito hospitalar: insuficiência renal crônica (26,1; 1,9 - 350,7), admissão prévia na unidade de terapia intensiva (15,6; 1,6 - 152,0), simplified acute physiologic score II > 50 pontos (11,9; 3,4 - 42,0) e idade > 55 anos (4,4; 1,6 - 12,3). CONCLUSÃO: A pneumonia associada à ventilação mecânica aumentou tempos de ventilação mecânica, permanência na unidade de terapia intensiva e no hospital, número de complicações, mas não a letalidade.

Clinical characteristics and treatment patterns among patients with ventilator-associated pneumonia

STUDY OBJECTIVES

To evaluate clinical characteristics and treatment patterns among patients with ventilator-associated pneumonia (VAP), including the implementation of and outcomes associated with deescalation therapy.

DESIGN

Prospective, observational, cohort study.

SETTING

Twenty ICUs throughout the United States.

PATIENTS

A total of 398 ICU patients meeting predefined criteria for suspected VAP.

INTERVENTIONS

Prospective, handheld, computer-based data collection regarding routine VAP management according to local institutional practices, including clinical and microbiological characteristics, treatment patterns, and outcomes.

MEASUREMENTS AND RESULTS

The most frequent ICU admission diagnoses in patients with VAP were postoperative care (15.6%), neurologic conditions (13.3%), sepsis (13.1%), and cardiac complications (10.8%). The mean (+/- SD) duration of mechanical ventilation prior to VAP diagnosis was 7.3 +/- 6.9 days. Major pathogens were identified in 197 patients (49.5%) through either tracheal aspirate or BAL fluid and included primarily methicillin-resistant Staphylococcus aureus (14.8%), Pseudomonas aeruginosa (14.3%), and other Staphylococcus species (8.8%). More than 100 different antibiotic regimens were prescribed as initial VAP treatment, the majority of which included cefepime (30.4%) or a ureidopenicillin/monobactam combination (27.9%). The mean duration of therapy was 11.8 +/- 5.9 days. In the majority of cases (61.6%), therapy was neither escalated nor deescalated. Escalation of therapy occurred in 15.3% of cases, and deescalation occurred in 22.1%. The overall mortality rate was 25.1%, with a mean time to death of 16.2 days (range, 0 to 49 days). The mortality rate was significantly lower among patients in whom therapy was deescalated (17.0%), compared with those experiencing therapy escalation (42.6%) and those in whom therapy was neither escalated nor deescalated (23.7%; chi2= 13.25; p = 0.001).

CONCLUSIONS

Treatment patterns for VAP vary widely from institution to institution, and the overall mortality rate remains unacceptably high. The deescalation of therapy in VAP patients appears to be associated with a reduction in mortality, which is an association that warrants further clinical study.

Clinical and economic consequences of ventilator-associated pneumonia: a systematic review

BACKGROUND

Ventilator-associated pneumonia (VAP) is the most common nosocomial infection in critically ill patients. The clinical and economic consequences of VAP are unclear, with a broad range of values reported in the literature

OBJECTIVE

To perform a systematic review to determine the incidence of VAP and its attributable mortality rate, length of stay, and costs.

DATA SOURCE

Computerized PUBMED and MEDLINE search supplemented by manual searches for relevant articles, limited to articles published after 1990.

STUDY SELECTION

English-language observational studies and randomized trials that provided data on the incidence of VAP were included. Matched cohort studies were included for calculation of attributable mortality rate and length of stay.

DATA EXTRACTION

Data were extracted on patient population, diagnostic criteria for VAP, incidence, outcome, type of intensive care unit, and study design.

DATA SYNTHESIS

The cumulative incidence of VAP was calculated by combining the results of several studies using standard formulas for combining proportions, in which the weighted average and variance are calculated. Results from studies comparing intensive care unit and hospital mortality due to VAP, additional length of stay, and additional days of mechanical ventilation were pooled using a random effects model, with assessment of heterogeneity.

RESULTS

Our findings indicate a) between 10% and 20% of patients receiving >48 hrs of mechanical ventilation will develop VAP; b) critically ill patients who develop VAP appear to be twice as likely to die compared with similar patients without VAP (pooled odds ratio, 2.03; 95% confidence interval, 1.16-3.56); c) patients with VAP have significantly longer intensive care unit lengths of stay (mean = 6.10 days; 95% confidence interval, 5.32-6.87 days); and d) patients who develop VAP incur > or = USD $10,019 in additional hospital costs.

CONCLUSIONS

Ventilator-associated pneumonia occurs in a considerable proportion of patients undergoing mechanical ventilation and is associated with substantial morbidity, a two-fold mortality rate, and excess cost. Given these findings, strategies that effectively prevent VAP are urgently needed.

Neumonía nosocomial en el enfermo no intubado

Hospital-acquired pneumonia is one of the main causes of nosocomial infection. Although its incidence is higher in intubated patients, around half of all cases occur outside the intensive care unit (ICU). However, few studies have been performed in this setting and consequently most data come from hospitalized series that include patients undergoing mechanical ventilation. The epidemiological differences between intubated patients and non-ICU patients suggest that the etiology and therapeutic approach differ between these two groups. The present article reviews the epidemiology, diagnosis, treatment and prevention of nosocomial pneumonia in general wards.

Health-Care–Associated Infections and Prevention

Health-care-associated infections (HAIs) are an important cause of perioperative morbidity and mortality. Currently, one out of every 10 surgical patients develops an HAI. Causes of HAIs vary, but include the transient immunodeficiency associated with surgery,immobility, and the presence of indwelling devices. With rates of antimicrobial resistance increasing, prevention remains the best solution. The investigators review the most frequently encountered health-care-associated infections with an emphasis on preventative strategies. The article addresses issues related to the diagnosis,treatment, and prevention of health-care-related pneumonia,health-care-associated urinary tract infections, and intravascular-catheter-related infections. The article also discusses the utility of hand hygiene policies.

Circulating immune parameters predicting the progression from hospital-acquired pneumonia to septic shock in surgical patients

Introduction

Hospital-acquired pneumonia after surgery is one of the major causes of septic shock. The excessive inflammatory response appears to be responsible for the increased susceptibility to infections and subsequent sepsis. The primary aim of this study was to investigate immune parameters at the onset of pneumonia, before the development of subsequent septic shock. The secondary aim was to investigate the usefulness of these immune parameters in predicting progression from hospital-acquired pneumonia to septic shock.

Methods

This propective clinical study included 76 patients with the diagnosis of hospital-acquired pneumonia. Approval was obtained from the local institutional ethics committee and relatives of the patients gave informed consent. Of the 76 patients, 29 subsequently developed septic shock. All patients were included within 4 h of establishing the diagnosis of hospital-acquired pneumonia (first collection of blood samples and the analysis of immune mediators). In addition, we defined early (within 12 h of onset of septic shock) and late (within 72 to 96 h of onset) stages of septic shock for the collection of blood samples and the analysis of immune mediators. The immune parameters tumor necrosis factor-α, IL-1β, IL-6, IL-8 and IL-10 as well as the endothelial leucocyte adhesion molecule were analyzed.

Results

In the pneumonia group with subsequent septic shock, levels of IL-1β, IL-6, IL-8 and IL-10 were significantly increased before the onset of septic shock compared to patients without subsequent septic shock. This progression was best predicted by IL-1β, IL-6, IL-8 and IL-10 (area under the curve ≥ 0.8).

Conclusion

At the onset of hospital-acquired pneumonia, a significant relevant systemic cytokine mediated response had already been initiated. It might, therefore, be possible to identify patients at risk for septic shock with these predictive markers during early pneumonia. In addition, immune modulating therapy might be considered as adjuvant therapy.

Antimicrobial treatment of lower respiratory tract infections in the hospital setting

Respiratory tract infections (RTIs) that may require hospitalization include acute exacerbations of chronic bronchitis (AECB), community-acquired pneumonia (CAP), and hospital-acquired pneumonia (HAP), which includes ventilator-associated pneumonia (VAP). Healthcare-associated pneumonia (HCAP) is treated similar to HAP and may be considered with HAP. For CAP requiring hospitalization, the current guidelines for the treatments of RTIs generally recommend either a beta-lactam and macrolide combination or a fluoroquinolone. The respiratory fluoroquinolones (levofloxacin, gatifloxacin, moxifloxacin, and gemifloxacin) are excellent antibiotics due to high levels of susceptibility among gram-negative, gram-positive, and atypical pathogens. The fluoroquinolones are active against > 98% of Streptococcus pneumoniae, including penicillin-resistant strains. Fluoroquinolones are also recommended for AECB requiring hospitalization. Evidence from clinical trials suggests that levofloxacin monotherapy is as efficacious as combination ceftriaxone-erythromycin therapy in the treatment of patients hospitalized with CAP. For early-onset HAP, VAP, and HCAP without the risk of multidrug resistance, ceftriaxone, ampicillin-sulbactam, ertapenem, or one of the fluoroquinolones is recommended. High-dose, short-course therapy regimens may offer improved treatment due to higher drug concentrations, more rapid killing, increased adherence, and the potential to reduce development of resistance. Recent studies have shown that short-course therapy with levofloxacin, azithromycin, or telithromycin in patients with CAP was effective, safe, and tolerable and may control the rate of resistance.

Prevention of pneumonia in the hospital setting

Although the optimal approach to reducing ventilator-associated pneumonia (VAP) is unclear, recent studies indicate that mandatory education of health care workers caring for mechanically ventilated patients can decrease overall VAP rates. Among the available interventions, shortening the duration of mechanical ventilation and providing measures to prevent the aspiration of contaminated secretions are most important. Given the evidence supporting greater morbidity, hospital mortality, and medical care costs among patients who have VAP, the prevention of this nosocomial infection should be an important priority in the hospital setting.

Multicenter study of hospital-acquired pneumonia in non-ICU patients

STUDY OBJECTIVE

To know the incidence, epidemiology, etiology, and outcome of hospital-acquired pneumonia (HAP) in non-ICUs adult patients.

SETTING

Twelve Spanish teaching hospitals.

INTERVENTIONS

From April 1999 to November 2000, non-ICU HAP was prospectively studied by active, bimonthly 1-week surveillance. Epidemiologic data, etiology, and evolution of pneumonia were recorded. Blood and sputum cultures and Legionella pneumophila and Streptococcus pneumoniae urinary antigen tests were performed.

RESULTS

We included 186 patients, with complete data available in 165 patients (70.3% male gender; mean age, 63.7 +/- 16.9 years [ +/- SD]) The mean incidence of HAP was 3 +/- 1.4 cases/1,000 hospital admissions. Most patients (64.2%) were in medical wards, had severe underlying diseases (66.6%), and had a hospital stay > 5 days (76.4%). Blood cultures were performed in 139 patients (84.2%), sputum cultures were performed in 89 patients (53.9%), and urinary antigen detection was performed in 123 patients (74.5%). An etiologic diagnosis was obtained in 60 cases (36.4%), and 31 were definitive. The most frequent etiologies were S pneumoniae (16 cases, 14 definitive), L pneumophila (7 cases, 7 definitive), Aspergillus sp (7 cases, 3 definitive), Pseudomonas aeruginosa (7 cases, 2 definitive), and several Enterobacteriaceae (8 cases, 4 definitive). Clinical complications occurred in 52.1% of the cases, and mortality was 26% (13.9% attributed to pneumonia).

CONCLUSIONS

Non-ICU HAP is an important cause of hospital morbidity, observed most frequently in medical wards and elderly patients with severe underlying diseases. In this setting, S pneumoniae and Legionella sp should be considered in addition to other nosocomial pathogens; urinary antigen detection is useful in determining the prevalence of these microorganisms.

Gamma interferon does not enhance clearance of Pseudomonas aeruginosa but does amplify a proinflammatory response in a murine model of postseptic immunosuppression

Patients that have suffered a major injury may sustain a period of immunocompromise and altered Th1/Th2 cytokine balance that can predispose them to opportunistic infections. Pseudomonas aeruginosa is frequently a causative organism for nosocomial infections in critically ill patients and is associated with high mortality. We previously mimicked this clinical scenario by challenging mice with P. aeruginosa 5 days after a cecal ligation and puncture (CLP) procedure. Mice that were subjected to CLP had reduced ability to clear bacteria, significantly lower gamma interferon (IFN-gamma) concentrations in plasma, and significantly elevated levels of interleukin 10 (IL-10) in plasma in response to the Pseudomonas challenge compared to uninjured control mice. We investigated the significance of the alteration in IFN-gamma by administering recombinant IFN-gamma to post-CLP mice at the time of Pseudomonas challenge and by challenging IFN-gamma knockout (IFN-gamma KO) mice with Pseudomonas. Administration of IFN-gamma to post-CLP mice attenuated IL-10 secretion and enhanced IL-12 secretion but did not improve bacterial clearance or survival after Pseudomonas challenge. Furthermore, IFN-gamma KO mice had significantly higher plasma IL-10 concentrations but did not exhibit impaired bacterial clearance or increased mortality following Pseudomonas challenge. These data indicate that systemic administration of IFN-gamma effectively reverses alterations in immune function that are commonly associated with immunosuppression in critically injured mice but does not improve bacterial clearance or survival following Pseudomonas challenge. Further, endogenous IFN-gamma does not appear to contribute significantly to early clearance of Pseudomonas bacteremia, nor does it affect the mortality rate after a lethal Pseudomonas challenge.

Antibiotic agents in the elderly

Diagnosis and treatment of infections in the elderly is challenging and complicated because of age-related physiologic changes and lack of classical clinical symptoms. Elderly patients are more vulnerable to infections because of their underlying diseases. This article reviews the pharmacologic issues in treating the elderly with antibiotics, the most frequently encountered infections in this patient population, and the suggested antibiotic regimens. The discussion also includes the special challenges of treating these most frequently encountered infections in the elderly who reside in long-term care facilities.

Prevention of hospital-associated pneumonia and ventilator-associated pneumonia

OBJECTIVE

To synthesize the available clinical data for the prevention of hospital-associated pneumonia (HAP) and ventilator-associated pneumonia (VAP) into a practical guideline for clinicians.

DATA SOURCE

A Medline database and references from identified articles were used to perform a literature search relating to the prevention of HAP/VAP.

CONCLUSIONS

There is convincing evidence to suggest that specific interventions can be employed to prevent HAP/VAP. The evidence-based interventions focus on the prevention of aerodigestive tract colonization (avoidance of unnecessary antibiotics and stress ulcer prophylaxis, use of sucralfate for stress ulcer prophylaxis, chlorhexidine oral rinse, selective digestive decontamination, short-course parenteral prophylactic antibiotics in high-risk patients) and the prevention of aspiration of contaminated secretions (preferred oral intubation, appropriate intensive care unit staffing, avoidance of tracheal intubation with the use of mask ventilation, application of weaning protocols and optimal use of sedation to shorten the duration of mechanical ventilation, semirecumbent positioning, minimization of gastric distension, subglottic suctioning, avoidance of ventilator circuit changes/manipulation, routine drainage of ventilator circuit condensate). Clinicians caring for patients at risk for HAP/VAP should promote the development and application of local programs encompassing these interventions based on local resource availability, occurrence rates of HAP/VAP, and the prevalence of infection due to antibiotic-resistant bacteria (Pseudomonas aeruginosa, Acinetobacter species, and methicillin-resistant Staphylococcus aureus).

Antimicrobial resistance among non-fermentative Gram-negative bacilli isolated from the respiratory tracts of Italian inpatients: a 3-year surveillance study by the Italian Epidemiological Survey

The Italian Epidemiological Survey evaluated antibiotic susceptibility of non-fermentative Gram-negative bacilli isolated from inpatient respiratory-tract specimens collected throughout Italy during 1997-1999. The minimal inhibitory concentrations of 14 antibiotics for 1474 Pseudomonas aeruginosa strains, 307 Stenotrophomonas maltophilia strains and 114 Acinetobacter baumannii strains were determined in 57 clinical microbiology laboratories by means of a standardised micro-dilution method. The most active drugs against P. aeruginosa isolates were meropenem (81% susceptible) and amikacin (80% susceptible). Imipenem and meropenem proved to be the only agents active against A. baumannii isolates, although 13 and 16%, respectively, of strains were resistant to these drugs. Trimethoprim-sulphamethoxazole (TMP-SMZ) showed activity only against S. maltophilia isolates (83% susceptible). A total of 185 multidrug-resistant P. aeruginosa isolates (resistant to piperacillin, ceftazidime, gentamicin, and imipenem) were found. Resistance rates and trends showed consistent regional variations, including sharp increases from 1997 to 1999 in imipenem resistance among P. aeruginosa isolates from central and southern Italy.

New developments in antibacterial choice for lower respiratory tract infections in elderly patients

Elderly patients are at increased risk of developing lower respiratory tract infections compared with younger patients. In this population, pneumonia is a serious illness with high rates of hospitalisation and mortality, especially in patients requiring admission to intensive care units (ICUs). A wide range of pathogens may be involved depending on different settings of acquisition and patient's health status. Streptococcus pneumoniae is the most common bacterial isolate in community-acquired pneumonia, followed by Haemophilus influenzae, Moraxella catarrhalis and atypical pathogens such as Chlamydia pneumoniae, Legionella pneumophila and Mycoplasma pneumoniae. However, elderly patients with comorbid illness, who have been recently hospitalised or are residing in a nursing home, may develop severe pneumonia caused by multidrug resistant staphylococci or pneumococci, and enteric Gram-negative bacilli, including Pseudomonas aeruginosa. Moreover, anaerobes may be involved in aspiration pneumonia. Timely and appropriate empiric treatment is required in order to enhance the likelihood of a good clinical outcome, prevent the spread of antibacterial resistance and reduce the economic impact of pneumonia. International guidelines recommend that elderly outpatients and inpatients (not in ICU) should be treated for the most common bacterial pathogens and the possibility of atypical pathogens. The algorithm for therapy is to use either a selected beta-lactam combined with a macrolide (azithromycin or clarithromycin), or to use monotherapy with a new anti-pneumococcal quinolone, such as levofloxacin, gatifloxacin or moxifloxacin. Oral (amoxicillin, amoxicillin/clavulanic acid, cefuroxime axetil) and intravenous (sulbactam/ampicillin, ceftriaxone, cefotaxime) beta-lactams are agents of choice in outpatients and inpatients, respectively. For patients with severe pneumonia or aspiration pneumonia, the specific algorithm is to use either a macrolide or a quinolone in combination with other agents; the nature and the number of which depends on the presence of risk factors for specific pathogens. Despite these recommendations, clinical resolution of pneumonia in the elderly is often delayed with respect to younger patients, suggesting that optimisation of antibacterial therapy is needed. Recently, some new classes of antibacterials, such as ketolides, oxazolidinones and streptogramins, have been developed for the treatment of multidrug resistant Gram-positive infections. However, the efficacy and safety of these agents in the elderly is yet to be clarified. Treatment guidelines should be modified on the basis of local bacteriology and resistance patterns, while dosage and/or administration route of each antibacterial should be optimised on the basis of new insights on pharmacokinetic/pharmacodynamic parameters and drug interactions. These strategies should be able to reduce the occurrence of risk factors for a poor clinical outcome, hospitalisation and death.