Bacterial pneumonia in hospitalized patients with HIV infection: the Pulmonary Complications, ICU Support, and Prognostic Factors of Hospitalized Patients with HIV (PIP) Study

Genomic and metabolic versatility of Pseudomonas aeruginosa contributes to its inter-kingdom transmission and survival

Pseudomonas aeruginosa is one of the most versatile bacteria with renowned pathogenicity and extensive drug resistance. The diverse habitats of this bacterium include fresh, saline and drainage waters, soil, moist surfaces, taps, showerheads, pipelines, medical implants, nematodes, insects, plants, animals, birds and humans. The arsenal of virulence factors produced by P. aeruginosa includes pyocyanin, rhamnolipids, siderophores, lytic enzymes, toxins and polysaccharides. All these virulent elements coupled with intrinsic, adaptive and acquired antibiotic resistance facilitate persistent colonization and lethal infections in different hosts. To date, treating pulmonary diseases remains complicated due to the chronic secondary infections triggered by hospital-acquired P. aeruginosa. On the contrary, this bacterium can improve plant growth by suppressing phytopathogens and insects. Notably, P. aeruginosa is one of the very few bacteria capable of trans-kingdom transmission and infection. Transfer of P. aeruginosa strains from plant materials to hospital wards, animals to humans, and humans to their pets occurs relatively often. Recently, we have identified that plant-associated P. aeruginosa strains could be pathologically similar to clinical isolates. In this review, we have highlighted the genomic and metabolic factors that facilitate the dominance of P. aeruginosa across different biological kingdoms and the varying roles of this bacterium in plant and human health.

Pathogen spectrum of community acquired pneumonia in people living with HIV (PLWH) in the German CAPNETZ-Cohort

OBJECTIVES

The objective of this study was to identify the pathogen spectrum of community acquired pneumonia in people living with HIV (PLWH), and to compare it with a matched HIV negative group in order to reassess therapeutic strategies for PLWH.

METHODS

Seventy-three (n = 73) PLWH (median CD4 3-6 months before CAP: 515/µl; SD 309) with community acquired pneumonia (CAP) were matched with 218 HIV-negative CAP controls in a prospective study design. Pathogen identifications used blood culture, samples from the upper and lower respiratory tract (culture and multiplex PCR) and urinary pneumococcal and legionella antigen test.

RESULTS

Although the vaccination rate among PLWH with CAP was significantly higher (pneumococcal vaccination: 27.4 vs. 8.3%, p < 0.001; influenza vaccination: 34.2 vs. 17.4%, p = 0.009), pneumococci were found most frequently as pathogen among both PLWH (n = 19/21.3%) and controls (n = 34/17.2%; p = 0.410), followed by Haemophilus influenzae (PLWH, n = 12/13.5%, vs. controls, n = 25 / 12.6%; p = 0.850). Staphylococcus aureus was found equally in 20.2 and 19.2% in PLWH and controls, but infection or colonization could not be distinguished. Mortality during 6-month follow-up was significantly higher for PLWH (5/73, or 6.8%) versus controls (3/218, or 1.4%), however with lower case numbers than previously reported. Typical HIV-associated pathogens such as Pneumocystis jirovecii were found only exceptionally.

CONCLUSIONS

Our study underscores the persistent clinical burden of CAP for PLWH. From pathogen perspective, empirical antibiotic treatment for CAP in PLWH on antiretroviral therapy should cover pneumococci and Haemophilus influenzae and may be adopted from valid common recommendations.

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.

Comparative Analysis of Complicated Urinary Tract Infections Caused by Extensively Drug-Resistant Pseudomonas aeruginosa and Extended-Spectrum β-Lactamase-Producing Klebsiella pneumoniae

The objective was to compare clinical characteristics, outcomes, and economic differences in complicated urinary tract infections (cUTI) caused by extensively drug-resistant Pseudomonas aeruginosa (XDR P. aeruginosa) and extended-spectrum beta-lactamase-producing Klebsiella pneumoniae (ESBL-K. pneumoniae). A retrospective study was conducted at a tertiary care hospital. Patients with XDR P. aeruginosa and ESBL-K. pneumoniae cUTIs were compared. The primary outcome was clinical failure at day 7 and at the end of treatment (EOT). Secondary outcomes: 30- and 90-day mortality, microbiological eradication, and economic cost. Two-hundred and one episodes were included, of which 24.8% were bloodstream infections. Patients with XDR P. aeruginosa cUTI more frequently received inappropriate empirical therapy (p < 0.001). Nephrotoxicity due to antibiotics was only observed in the XDR P. aeruginosa group (26.7%). ESBL-K. pneumoniae cUTI was associated with worse eradication rates, higher recurrence, and higher infection-related readmission. In multivariate analysis, XDR P. aeruginosa was independently associated with clinical failure on day 7 of treatment (OR 4.34, 95% CI 1.71−11.04) but not at EOT, or with mortality. Regarding hospital resource consumption, no significant differences were observed between groups. XDR P. aeruginosa cUTI was associated with worse early clinical cures and more antibiotic side effects than ESBL-K. pneumoniae infections. However, no differences in mortality or in hospitalization costs were observed.

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

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

Molecular and structural facets of c-di-GMP signalling associated with biofilm formation in Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic human pathogen and is the primary cause of nosocomial infections. Biofilm formation by this organism results in chronic and hard to eradicate infections. The intracellular signalling molecule bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) is a secondary messenger in bacterial cells crucial for motile to sessile transition. The signalling pathway components encompass two classes of enzymes with antagonistic activities, the diguanylate cyclases (DGCs) and phosphodiesterases (PDEs) that regulate the cellular levels of c-di-GMP at distinct stages of biofilm initiation, maturation and dispersion. This review summarizes the structural analysis and functional studies of the DGCs and PDEs involved in biofilm regulation in P. aeruginosa. In addition, we also describe the effector proteins that sense the perturbations in c-di-GMP levels to elicit a functional output. Finally, we discuss possible mechanisms that allow the dynamic levels of c-di-GMP to regulate cognate cellular response. Uncovering the details of the regulation of the c-di-GMP signalling pathway is vital for understanding the behaviour of the pathogen and characterization of novel targets for anti-biofilm interventions.

H-NS-like proteins in Pseudomonas aeruginosa coordinately silence intragenic transcription

The H-NS-like proteins MvaT and MvaU act coordinately as global repressors in Pseudomonas aeruginosa by binding to AT-rich regions of the chromosome. Although cells can tolerate loss of either protein, identifying their combined regulatory effects has been challenging because the loss of both proteins is lethal due to induction of prophage Pf4 and subsequent superinfection of the cell. In other bacteria, H-NS promotes the cellular fitness by inhibiting intragenic transcription from AT-rich target regions, preventing them from sequestering RNA polymerase; however, it is not known whether MvaT and MvaU function similarly. Here, we utilize a parental strain that cannot be infected by Pf4 phage to define the collective MvaT and MvaU regulon and demonstrate that the combined loss of both MvaT and MvaU leads to increased intragenic transcription from loci directly controlled by these proteins. We further show that the loss of MvaT and MvaU leads to a striking redistribution of RNA polymerase containing σ⁷⁰ to genomic regions vacated by these proteins. Our findings suggest that the ability of H-NS-like proteins to repress intragenic transcription is a universal function of these proteins and point to a second mechanism by which MvaT and MvaU may contribute to the growth of P. aeruginosa.

HIV Impairs Alveolar Macrophage Function via MicroRNA-144-Induced Suppression of Nrf2

BACKGROUND

Despite anti-retroviral therapy, HIV-1 infection increases the risk of pneumonia and causes oxidative stress and defective alveolar macrophage (AM) immune function. We have previously determined that HIV-1 proteins inhibit antioxidant defenses and impair AM phagocytosis by suppressing nuclear factor (erythroid-derived 2)-like 2 (Nrf2). Given its known effects on Nrf2, we hypothesize miR-144 mediates the HIV-1 induced suppression of Nrf2.

METHODS

Primary AMs isolated from HIV-1 transgenic (HIV-1 Tg) rats and wild type littermates (WT) as well as human monocyte-derived macrophages (MDMs) infected ex vivo with HIV-1 were used. We modulated miR-144 expression using a miR-144 mimic or an inhibitor to assay its effects on Nrf2/ARE activity and AM functions in vitro and in vivo.

RESULTS

MiR-144 expression was increased in AMs from HIV-1 Tg rats and in HIV-1-infected human MDMs compared to cells from WT rats and non-infected human MDMs, respectively. Increasing miR-144 with a miR-144 mimic inhibited the expression of Nrf2 and its downstream effectors in WT rat macrophages and consequently impaired their bacterial phagocytic capacity and H₂O₂ scavenging ability. These effects on Nrf2 expression and AM function were reversed by antagonizing miR-144 ex vivo or in the airways of HIV-1 Tg rats in vivo, but this protection was abrogated by silencing Nrf2 expression.

CONCLUSIONS

Our results suggest that inhibiting miR-144 or interfering with its deleterious effects on Nrf2 attenuates HIV-1-mediated AM immune dysfunction and improves lung health in individuals with HIV.

Emergence of antibiotic resistance Pseudomonas aeruginosa in intensive care unit; a critical review

The emergence of antibiotic resistant bacteria in the healthcare is a serious concern. In the Healthcare premises precisely intensive care unit are major sources of microbial diversity. Recent findings have demonstrated not only microbial diversity but also drug resistant microbes largely habitat in ICU. Pseudomonas aeruginosa found as a part of normal intestinal flora and a significant pathogen responsible for wide range of ICU acquired infection in critically ill patients. Nosocomial infection associated with this organism including gastrointestinal infection, urinary tract infections and blood stream infection. Infection caused by this organism are difficult to treat because of the presence of its innate resistance to many antibiotics (β-lactam and penem group of antibiotics), and its ability to acquire further resistance mechanism to multiple class of antibiotics, including Beta-lactams, aminoglycosides and fluoroquinolones. In the molecular evolution microbes adopted several mechanism to maintain genomic plasticity. The tool microbe use for its survival is mainly biofilm formation, quorum sensing, and horizontal gene transfer and enzyme promiscuity. Such genomic plasticity provide an ideal habitat to grow and survive in hearse environment mainly antibiotics pressure. This review focus on infection caused by Pseudomonas aeruginosa, its mechanisms of resistance and available treatment options. The present study provides a systemic review on major source of Pseudomonas aeruginosa in ICU. Further, study also emphasizes virulence gene/s associated with Pseudomonas aeruginosa genome for extended drug resistance. Study gives detailed overview of antibiotic drug resistance mechanism.

Epidemiology and outcome of HIV-infected patients admitted to the ICU in the current highly active antiretroviral therapy era

PURPOSE

To describe the epidemiology of critical disease in HIV-infected patients during the current highly active antiretroviral therapy (HAART) era and to identify hospital mortality predictors.

METHODS

A longitudinal, retrospective observational study was made of HIV-infected adults admitted to the ICU in two Spanish hospitals between 1 January 2000 and 31 December 2014. Demographic and HIV-related variables were analyzed, together with comorbidities, severity scores, reasons for admission and need for organ support. The chi-squared test was used to compare categorical variables, while continuous variables were contrasted with the Student's t-test, Mann-Whitney U-test or Kruskal-Wallis test, assuming an alpha level=0.05. Multivariate logistic regression analysis was used to calculate odds ratios for assessing correlations to mortality during hospital stay. Joinpoint regression analysis was used to study mortality trends over time.

RESULTS

A total of 283 episodes were included for analyses. Hospital mortality was 32.9% (95%CI: 21.2-38.5). Only admission from a site other than the Emergency Care Department (OR 3.64, 95%CI: 1.30-10.20; p=0.01), moderate-severe liver disease (OR 5.65, 95%CI: 1.11-28.87; p=0.04) and the APACHE II score (OR 1.14, 95%CI: 1.04-1.26; p<0.01) and SOFA score at 72h (OR 1.19, 95%CI: 1.02-1.40; p=0.03) maintained a statistically significant relationship with hospital mortality.

CONCLUSIONS

Delayed ICU admission, comorbidities and the severity of critical illness determine the prognosis of HIV-infected patients admitted to the ICU. Based on these data, HIV-infected patients should receive the same level of care as non-HIV-infected patients, regardless of their immunological or nutritional condition.

Full blood count values as a predictor of poor outcome of pneumonia among HIV-infected patients

BACKGROUND

To evaluate the predictive value of analytical markers of full blood count that can be assessed in the emergency department for HIV infected patients, with community-acquired pneumonia (CAP).

METHODS

Prospective 3-year study including all HIV-infected patients that went to our emergency department with respiratory clinical infection, more than 24-h earlier they were diagnosed with CAP and required admission. We assessed the different values of the first blood count performed on the patient as follows; total white blood cells (WBC), neutrophils, lymphocytes (LYM), basophils, eosinophils (EOS), red blood cells (RBC), hemoglobin, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin concentration, mean corpuscular hemoglobin, red blood cell distribution width (RDW), platelets (PLT), mean platelet volume, and platelet distribution width (PDW). The primary outcome measure was 30-day mortality and the secondary, admission to an intensive care unit (ICU). The predictive power of the variables was determined by statistical calculation.

RESULTS

One hundred sixty HIV-infected patients with pneumonia were identified. The mean age was 42 (11) years, 99 (62%) were male, 79 (49%) had ART. The main route of HIV transmission was through parenteral administration of drugs. Streptococcus pneumonia was the most frequently identified etiologic agent of CAP The univariate analysis showed that the values of PLT (p < 0.009), EOS (p < 0.033), RDW (p < 0.033) and PDW (p < 0.09) were predictor of mortality, but after the logistic regression analysis, no variable was shown as an independent predictor of mortality. On the other hand, higher RDW (OR = 1.2, 95% CI 1.1-1.4, p = 0.013) and a lower number of LYM (OR 2.2, 95% CI 1.1-2.2; p = 0.035) were revealed as independent predictors of admission to ICU.

CONCLUSION

Red blood cell distribution and lymphocytes were the most useful predictors of disease severity identifying HIV infected patients with CAP who required ICU admission.

Pulmonary disease in HIV-infected adults in the era of antiretroviral therapy

: HIV in the antiretroviral therapy era is characterized by multimorbidity and the frequent occurrence of HIV-associated non-AIDS chronic health conditions. Respiratory symptoms and chronic pulmonary diseases, including chronic obstructive pulmonary disease, asthma, and cardiopulmonary dysfunction, are among the conditions that may present in persons living with HIV. Tobacco smoking, which is disproportionately high among persons living HIV, strongly contributes to the risk of pulmonary disease. Additionally, features associated with and at times unique to HIV, including persistent inflammation, immune cell activation, oxidative stress, and dysbiosis, may also contribute. This review summarizes the available literature regarding epidemiology of and risk factors for respiratory symptoms and chronic pulmonary disease in the current era.

Characteristics of hospital admissions for pneumonia in HIV-positive individuals in Winnipeg, Manitoba: a cross-sectional retrospective analysis

Lung infection in human immunodeficiency virus (HIV)-positive individuals remains an important cause of morbidity and mortality, even in the current antiretroviral therapy era. Pneumonia is the most common cause of admission in HIV-positive individuals in our centre as reported in a previously published study. The objective of this retrospective observational study was to further characterize these admissions, with respect to index of disease severity at presentation, organisms identified, and investigations pursued including bronchoalveolar lavage (BAL). There were 123 unique patients accounting for a total of 209 admissions from 2005 to 2015. An organism was isolated in only 33% of all admissions (68/209). The most common organism was Pneumocystis jirovecii with a frequency of 29% of all admissions. Eighty-seven percent of presentations were mild, and 13% were moderate by CURB-65 criteria. A total of 39 BALs were performed, of which 27 yielded an organism (69%). Considering the burden of disease, low diagnostic yield of the current diagnostic strategy and increased morbidity and mortality caused by pneumonia in HIV-positive individuals, further methods are needed to more accurately target therapy. The preponderance of mild disease in this study suggests that better diagnostic tests may identify individuals that can be candidates for outpatient therapy.

Tracking the Dynamic Relationship between Cellular Systems and Extracellular Subproteomes in Pseudomonas aeruginosa Biofilms

The transition of the opportunistic pathogen Pseudomonas aeruginosa from free-living bacteria into surface-associated biofilm communities represents a viable target for the prevention and treatment of chronic infectious disease. We have established a proteomics platform that identified 2443 and 1142 high-confidence proteins in P. aeruginosa whole cells and outer-membrane vesicles (OMVs), respectively, at three time points during biofilm development (ProteomeXchange identifier PXD002605). The analysis of cellular systems, specifically the phenazine biosynthetic pathway, demonstrates that whole-cell protein abundance correlates to end product (i.e., pyocyanin) concentrations in biofilm but not in planktonic cultures. Furthermore, increased cellular protein abundance in this pathway results in quantifiable pyocyanin in early biofilm OMVs and OMVs from both growth modes isolated at later time points. Overall, our data indicate that the OMVs being released from the surface of the biofilm whole cells have unique proteomes in comparison to their planktonic counterparts. The relative abundance of OMV proteins from various subcellular sources showed considerable differences between the two growth modes over time, supporting the existence and preferential activation of multiple OMV biogenesis mechanisms under different conditions. The consistent detection of cytoplasmic proteins in all of the OMV subproteomes challenges the notion that OMVs are composed of outer membrane and periplasmic proteins alone. Direct comparisons of outer-membrane protein abundance levels between OMVs and whole cells shows ratios that vary greatly from 1:1 and supports previous studies that advocate the specific inclusion, or "packaging", of proteins into OMVs. The quantitative analysis of packaged protein groups suggests biogenesis mechanisms that involve untethered, rather than absent, peptidoglycan-binding proteins. Collectively, individual protein and biological system analyses of biofilm OMVs show that drug-binding cytoplasmic proteins and porins are potentially shuttled from the whole cell into the OMVs and may contribute to the antibiotic resistance of P. aeruginosa whole cells within biofilms.

CURB-65 and other markers of illness severity in community-acquired pneumonia among HIV-positive patients

As the relative burden of community-acquired bacterial pneumonia among HIV-positive patients increases, adequate prediction of case severity on presentation is crucial. We sought to determine what characteristics measurable on presentation are predictive of worse outcomes. We studied all admissions for community-acquired bacterial pneumonia over one year at a tertiary centre. Patient demographics, comorbidities, HIV-specific markers and CURB-65 scores on Emergency Department presentation were reviewed. Outcomes of interest included mortality, bacteraemia, intensive care unit admission and orotracheal intubation. A total of 396 patients were included: 49 HIV-positive and 347 HIV-negative. Mean CURB-65 score was 1.3 for HIV-positive and 2.2 for HIV-negative patients (p < 0.0001), its predictive value for mortality being maintained in both groups (p = 0.03 and p < 0.001, respectively). Adjusting for CURB-65 scores, HIV infection by itself was only associated with bacteraemia (adjusted odds ratio [AOR] 7.1, 95% CI [2.6-19.5]). Patients with < 200 CD4 cells/µL presented similar CURB-65 adjusted mortality (aOR 1.7, 95% CI [0.2-15.2]), but higher risk of intensive care unit admission (aOR 5.7, 95% CI [1.5-22.0]) and orotracheal intubation (aOR 9.1, 95% CI [2.2-37.1]), compared to HIV-negative patients. These two associations were not observed in the > 200 CD4 cells/µL subgroup (aOR 2.2, 95% CI [0.7-7.6] and aOR 0.8, 95% CI [0.1-6.5], respectively). Antiretroviral therapy and viral load suppression were not associated with different outcomes (p > 0.05). High CURB-65 scores and CD4 counts < 200 cells/µL were both associated with worse outcomes. Severity assessment scales and CD4 counts may both be helpful in predicting severity in HIV-positive patients presenting with community-acquired bacterial pneumonia.

Level of understanding of co-trimoxazole use among HIV infected, recurrent pulmonary tuberculosis suspects at a national referral tuberculosis clinic in Kampala, Uganda: a qualitative analysis

BACKGROUND

Co-trimoxazole use is the standard of care for preventing Pneumocystis jirovecii pneumonia in sub-Saharan Africa but implementation remains slow. Co-trimoxazole is self- administered with uncertain adherence. Knowledge of co-trimoxazole use among HIV infected persons is unknown.

OBJECTIVES

To assess knowledge, attitudes and practices of co-trimoxazole use among HIV infected adults evaluated for recurrent PTB in Kampala, Uganda.

METHODS

A qualitative study utilizing 5 focus group discussions among 30 HIV infected PTB suspects at the national referral tuberculosis treatment centre in Kampala.

RESULTS

Males and females had similar median ages. 80% were currently on co-trimoxazole and 50% of participants were on HAART. Majority of participants defined co-trimoxazole as an analgesic. Few noted co-trimoxazole was a drug to treat cough and chest pain. However, few responses revealed that co-trimoxazole prevents opportunistic diseases among PLHIV. Most of participants believed HAART and anti-TB drugs work as co-trimoxazole thus it should not be taken together with them. This belief may lead to increased risk of opportunistic infections, morbidity and mortality.

CONCLUSIONS

We revealed gaps in understanding of co-trimoxazole use among study participants. We therefore recommend that more facts about co-trimoxazle as prophylaxis against P. jirovecii, bacterial and diarrheal pathogens should be incorporated in VCT fact sheets.

Antimicrobial targets localize to the extracellular vesicle-associated proteome of Pseudomonas aeruginosa grown in a biofilm

Microbial biofilms are particularly resistant to antimicrobial therapies. These surface-attached communities are protected against host defenses and pharmacotherapy by a self-produced matrix that surrounds and fortifies them. Recent proteomic evidence also suggests that some bacteria, including the opportunistic pathogen Pseudomonas aeruginosa, undergo modifications within a biofilm that make them uniquely resistant compared to their planktonic (free-living) counterparts. This study examines 50 proteins in the resistance subproteome of both surface-associated and free-living P. aeruginosa PAO1 over three time points. Proteins were grouped into categories based on their roles in antimicrobial: (i) binding, (ii) efflux, (iii) resistance, and (iv) susceptibility. In addition, the extracellular outer membrane vesicle-associated proteome is examined and compared between the two growth modes. We show that in whole cells between 12-24% of the proteins are present at significantly different abundance levels over time, with some proteins being unique to a specific growth mode; however, the total abundance levels in the four categories remain consistent. In contrast, marked differences are seen in the protein content of the outer membrane vesicles, which contain a greater number of drug-binding proteins in vesicles purified from late-stage biofilms. These results show how the method of analysis can impact the interpretation of proteomic data (i.e., individual proteins vs. systems), and highlight the advantage of using protein-based methods to identify potential antimicrobial resistance mechanisms in extracellular sample components. Furthermore, this information has the potential to inform the development of specific antipseudomonal therapies that quench possible drug-sequestering vesicle proteins. This strategy could serve as a novel approach for combating the high-level of antimicrobial resistance in P. aeruginosa biofilms.

Pseudomonas aeruginosa biofilms: mechanisms of immune evasion

The opportunistic gram-negative bacterium Pseudomonas aeruginosa is implicated in many chronic infections and is readily isolated from chronic wounds, medical devices, and the lungs of cystic fibrosis patients. P. aeruginosa is believed to persist in the host organism due to its capacity to form biofilms, which protect the aggregated, biopolymer-embedded bacteria from the detrimental actions of antibiotic treatments and host immunity. A key component in the protection against innate immunity is rhamnolipid, which is a quorum sensing (QS)-regulated virulence factor. QS is a cell-to-cell signaling mechanism used to coordinate expression of virulence and protection of aggregated biofilm cells. Rhamnolipids are known for their ability to cause hemolysis and have been shown to cause lysis of several cellular components of the human immune system, for example, macrophages and polymorphonuclear leukocytes (PMNs). In this chapter, the interplay between P. aeruginosa and the PMNs in chronic infections is discussed with focus on the role of rhamnolipids and extracellular DNA.

Aetiology of pulmonary symptoms in HIV-infected smear negative recurrent PTB suspects in Kampala, Uganda: a cross-sectional study

Introduction

Previously treated TB patients with pulmonary symptoms are often considered recurrent TB suspects in the resource-limited settings, where investigations are limited to microscopy and chest x-ray. Category II anti-TB drugs may be inappropriate and may expose patients to pill burden, drug toxicities and drug-drug interactions.

Objective

To determine the causes of pulmonary symptoms in HIV-infected smear negative recurrent pulmonary tuberculosis suspects at Mulago Hospital, Kampala.

Methods

Between March 2008 and December 2011, induced sputum samples of 178 consented HIV-infected smear negative recurrent TB suspects in Kampala were subjected to MGIT and LJ cultures for mycobacteria at TB Reference Laboratory, Kampala. Processed sputum samples were also tested by PCR to detect 18S rRNA gene of P.jirovecii and cultured for other bacteria.

Results

Bacteria, M. tuberculosis and Pneumocystis jirovecii were detected in 27%, 18% and 6.7% of patients respectively and 53.4% of the specimens had no microorganisms. S. pneumoniae, M. catarrhalis and H. influenzae were 100% susceptible to chloramphenicol and erythromycin but co-trimoxazole resistant.

Conclusion

At least 81.5% of participants had no microbiologically-confirmed TB. However our findings call for thorough investigation of HIV-infected smear negative recurrent TB suspects to guide cost effective treatment.

Clinical review: Respiratory failure in HIV-infected patients--a changing picture

Respiratory failure in HIV-infected patients is a relatively common presentation to ICU. The debate on ICU treatment of HIV-infected patients goes on despite an overall decline in mortality amongst these patients since the AIDS epidemic. Many intensive care physicians feel that ICU treatment of critically ill HIV patients is likely to be futile. This is mainly due to the unfavourable outcome of HIV patients with Pneumocystis jirovecii pneumonia who need mechanical ventilation. However, the changing spectrum of respiratory illness in HIV-infected patients and improved outcome from critical illness remain under-recognised. Also, the awareness of certain factors that can affect their outcome remains low. As there are important ethical and practical implications for intensive care clinicians while making decisions to provide ICU support to HIV-infected patients, a review of literature was undertaken. It is notable that the respiratory illnesses that are not directly related to underlying HIV disease are now commonly encountered in the highly active antiretroviral therapy (HAART) era. The overall incidence of P. jirovecii as a cause of respiratory failure has declined since the AIDS epidemic and sepsis including bacterial pneumonia has emerged as a frequent cause of hospital and ICU admission amongst HIV patients. The improved overall outcome of HIV patients needing ICU admission is related to advancement in general ICU care, including adoption of improved ventilation strategies. An awareness of respiratory illnesses in HIV-infected patients along with an appropriate diagnostic and treatment strategy may obviate the need for invasive ventilation and improve outcome further. HIV-infected patients presenting with respiratory failure will benefit from early admission to critical care for treatment and support. There is evidence to suggest that continuing or starting HAART in critically ill HIV patients is beneficial and hence should be considered after multidisciplinary discussion. As a very high percentage (up to 40%) of HIV patients are not known to be HIV infected at the time of ICU admission, the clinicians should keep a low threshold for requesting HIV testing for patients with recurrent pneumonia.

Evaluation of respiratory disease

The spectrum of HIV-associated pulmonary diseases is broad. Opportunistic infections, neoplasms, and noninfectious complications are all major considerations. Clinicians caring for persons infected with HIV must have a systematic approach. The approach begins with a thorough history and physical examination and often involves selected laboratory tests and a chest radiograph. Frequently, the clinical, laboratory, and chest radiographic presentation suggests a specific diagnosis or a few diagnoses, which then prompts specific diagnostic testing and treatment. This article presents an overview of the evaluation of respiratory disease in persons with HIV/AIDS.

Characteristics of Drug-Susceptible and Drug-Resistant Staphylococcus aureus Pneumonia in Patients with HIV

Objectives

To examine predictors and outcomes of Staphylococcus aureus Pneumonia (SAP) in people with HIV compared with Streptococcus pneumoniae Pneumonia (SPP), and to compare Methicillin-Resistant S. aureus (MRSA) with Methicillin-Sensitive S. aureus (MSSA) pneumonias in this population.

Methods

We conducted a retrospective case-control study of HIV-infected patients admitted to a single center with culture-proven S. aureus or S. pneumoniae pneumonia. We identified patients through a computerized database, conducted structured chart reviews, and performed bivariate and multivariate analyses using logistic regression.

Results

We compared 47 SAP episodes in 42 patients with 100 SPP episodes in 93 patients. Use of any antibiotics prior to admission (OR=3.5, p=0.02), a co-morbid illness (OR=4.2, p=0.04), and recent healthcare contact (OR=12.0, p<0.001) were significant independent predictors of SAP. Patients with SAP were more likely to require intensive care (OR=2.7, p=0.02) and mechanical ventilation (OR=3.1, p=0.02), but not to die. MRSA was more common (57% of cases) than MSSA, but outcomes were not significantly worse.

Conclusions

Patients with HIV and SAP have worse outcomes than those with SPP. Clinicians should consider empiric antibiotic coverage for MRSA in patients admitted with HIV and pneumonia, given the high prevalence of MRSA. Further studies are warranted to examine morbidity differences between HIV-associated MSSA and MRSA pneumonia.

Alcohol, HIV/AIDS, and Liver Disease

Globally, there are over 33 million persons living with HIV/AIDS resulting in 1.8 million deaths annually. While the rate of HIV transmission is slowing, it is estimated that 2.6 million new infections occur yearly [1]. In the United States, there are approximately 1.2 million living with HIV/AIDS, with 50,000 new HIV infections and 17,000 deaths from the disease annually [2]. For those who can obtain effective antiretroviral therapy (ART), HIV/AIDS has become a chronic disease with life expectancies over 30 years [3]. Research in the last 10 years has revealed the importance of alcohol in the HIV/AIDS epidemic. Alcohol use, in moderate or hazardous amounts, has been associated with increased acquisition of HIV infection, progression of HIV infection, deleterious effects on HIV treatment, and acceleration in the comorbidities of HIV infection [4–9]. Yet alcohol remains the “forgotten drug” of the HIV/AIDS epidemic [10].

[Bacterial pneumonia in HIV-infected patients (excluding mycobacterial infection)]

Respiratory infections are the most common complications in HIV patients, regardless of the degree of immunosuppression. Even though antiretroviral therapy has a protective effect on the risk of bacterial pneumonia, this still remains high (including those with CD(4)>500/mm(3)). The most frequently isolated bacteria are Streptococcus pneumoniae and Haemophilus influenzae. The clinical and radiological presentations of lower respiratory tract infections in HIV patients are quite variable. The clinical presentation is more severe and the radiological presentation is more atypical if the immunosuppression is severe. The first-line antibiotic therapy is an injectable third-generation cephalosporin (ceftriaxone or cefotaxime) or co-amoxiclav. Pneumococcal vaccination (as well as influenza vaccine) is recommended. Although rare, Nocardia spp. and Rhodococcus equi seem more common among AIDS patients.

Prevention of lung injury by Muc1 mucin in a mouse model of repetitive Pseudomonas aeruginosa infection

OBJECTIVE AND DESIGN

To determine whether repetitive airway Pseudomonas aeruginosa (Pa) infection results in lung inflammation and injury and, if so, whether these responses are affected by Muc1 mucin. Muc1 wild type (WT) and knockout (KO) mice were compared for body weights, lung inflammatory responses, and airspace enlargement using a chronic lung infection model system.

MATERIALS

Mice were treated intranasally with Pa (10(7) CFU) on days 0, 4, 7 and 10. On day 14, body weights, inflammatory cell numbers in bronchoalveolar lavage fluid (BALF), and airspace enlargement were measured. Differences in inflammatory responses between groups were statistically analyzed by the Student's t test and ANOVA.

RESULTS

Muc1 WT mice exhibited mild degrees of both inflammation and airspace enlargement following repetitive airway Pa infection. However, Muc1 KO mice exhibited significantly decreased body weights, greater macrophage numbers in the BALF, and increased airspace enlargement compared with Muc1 WT mice.

CONCLUSIONS

This is the first report demonstrating that Muc1 deficiency can lead to lung injury during chronic Pa infection in mice. These results suggest that MUC1 may play a crucial role in the resolution of inflammation during chronic respiratory infections and that MUC1 dysfunction likely contributes to the pathogenesis of chronic inflammatory respiratory disease.

Lung Disease in Older Patients with HIV

Successful treatment of HIV with combination antiretroviral therapy (ART) has resulted in an aging HIV-infected population. As HIV-infected patients are living longer, noninfectious pulmonary diseases are becoming increasingly prevalent with a proportional decline in the incidence of opportunistic infections (OIs). Pulmonary OIs such as Pneumocystis jirovecii pneumonia (PCP) and tuberculosis are still responsible for a significant proportion of pulmonary diseases in HIV-infected patients. However, bacterial pneumonia (BP) and noninfectious pulmonary diseases such as chronic obstructive pulmonary disease (COPD), lung cancer, pulmonary arterial hypertension (PAH), and interstitial lung disease (ILD) account for a growing number of pulmonary diseases in aging HIV-infected patients. The purpose of this chapter is to discuss the spectrum and management of pulmonary diseases in aging HIV-infected patients, although limited data exists to guide management of many noninfectious pulmonary diseases in HIV-infected patients. In the absence of such data, treatment of lung diseases in HIV-infected patients should generally follow guidelines for management established in HIV-uninfected patients.

HIV-1 transgene expression in rats induces differential expression of tumor necrosis factor alpha and zinc transporters in the liver and the lung

BACKGROUND

Highly effective antiviral treatment can suppress HIV-1 infection, but the chronic effects of HIV-1-related viral proteins, including gp120 and Tat, on organs such as the lungs can be damaging. HIV-1 transgenic rodent models are useful for studying the systemic effects of these proteins independently of viral infection. We have previously shown that HIV-1 transgene expression (and therefore, HIV-1-related protein expression) in rats decreases alveolar macrophage zinc levels and phagocytic capacity by unknown mechanisms. We hypothesized that HIV-1 transgene expression induces chronic inflammation and zinc sequestration within the liver and thereby decreases zinc bioavailability in the lung. We examined the expression of the pro-inflammatory cytokine, tumor necrosis factor alpha (TNFα), the zinc storage protein, metallothionein (MT1), and the zinc exporter, ZNT1 in the livers and the lungs of wild type and HIV-1 transgenic rats ± dietary zinc supplementation. In addition, we measured zinc levels, the zinc importing protein ZIP1, and the phagocytic capacity in the alveolar macrophages.

RESULTS

HIV-1 transgene expression increased the liver-specific expression of TNFα, suggesting a chronic inflammatory response within the liver in response to HIV-1-related protein expression. In parallel, HIV-1 transgene expression significantly increased MT1 and ZNT1 expression in the liver as compared to the lung, a pattern that is consistent with zinc sequestration in the liver as occurs during systemic inflammation. Further, HIV-1 transgene expression decreased intracellular zinc levels and increased expression of ZIP1 in the alveolar macrophages, a pattern consistent with zinc deficiency, and decreased their bacterial phagocytic capacity. Interestingly, dietary zinc supplementation in HIV-1 transgenic rats decreased gene expression of TNFα, MT1, and ZNT1 in the liver while simultaneously increasing their expression in the lung. In parallel, zinc supplementation increased alveolar macrophage intracellular zinc levels and bacterial phagocytic capacity in HIV-1 transgenic rats.

CONCLUSION

Taken together, these findings suggest that chronic HIV-1-related protein expression causes liver inflammation and zinc sequestration, which in turn limits zinc bioavailability in the lung and thereby impairs alveolar macrophage phagocytic function. Importantly, dietary zinc supplementation decreases liver inflammation and zinc sequestration and restores alveolar macrophage phagocytic function in HIV-1 transgenic rats, a result with potential clinical implications for improving lung health in HIV-1-infected individuals.

Imaging lung manifestations of HIV/AIDS

Advances in our understanding of human immunodeficiency virus (HIV) infection have led to improved care and incremental increases in survival. However, the pulmonary manifestations of HIV/acquired immunodeficiency syndrome (AIDS) remain a major cause of morbidity and mortality. Respiratory complaints are not infrequent in patients who are HIV positive. The great majority of lung complications of HIV/AIDS are of infectious etiology but neoplasm, interstitial pneumonias, Kaposi sarcoma and lymphomas add significantly to patient morbidity and mortality. Imaging plays a vital role in the diagnosis and management of lung of complications associated with HIV. Accurate diagnosis is based on an understanding of the pathogenesis of the processes involved and their imaging findings. Imaging also plays an important role in selection of the most appropriate site for tissue sampling, staging of disease and follow-ups. We present images of lung manifestations of HIV/AIDS, describing the salient features and the differential diagnosis.

The changing epidemiology of HIV-infected patients in the intensive care unit

With the introduction of highly active antiretroviral therapy (HAART), HIV has become a chronic disease. As HIV-infected patients are aging, they are at increased risk for comorbid diseases. These non-AIDS related diseases account for a growing proportion of intensive care unit (ICU) admissions in HIV-infected patients in recent studies. HIV-infected patients still present to the ICU with HIV-related conditions such as Pneumocystis jirovecii pneumonia (PCP), but these conditions are becoming less common. Respiratory failure remains the most common indication for ICU admission. Immune reconstitution inflammatory response syndrome and toxicities related to HAART may also result in ICU admission. While ICU survival has improved since the earliest era of the HIV epidemic, hospital mortality for HIV-infected patients admitted to the ICU remains around 30%. Risk factors for ICU mortality include poor functional status, weight loss, more than one year between HIV diagnosis and ICU admission, lower serum albumin, higher severity of illness, need for mechanical ventilation, and respiratory failure-particularly if due to PCP and accompanied by pneumothorax. The impact of HAART on ICU outcomes is unclear. HAART administration in the ICU can be challenging due to limited delivery routes, concern for viral resistance and medication toxicities. There are no data to determine the safety or efficacy of HAART initiation in the ICU. Future studies are needed to address the role of age, associated comorbidities and impact of HAART on outcomes of HIV-infected patients admitted to the ICU.

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.

Administration of nonviral gene vector encoding rat beta-defensin-2 ameliorates chronic Pseudomonas aeruginosa lung infection in rats

BACKGROUND

Beta-defensin-2 (BD-2) plays an important role in host defense against pathogenic microbe challenge by its direct antimicrobial activity and immunomodulatory functions. The present study aimed to determine whether genetic up-regulation of rat BD-2 (rBD-2) could ameliorate chronic Pseudomonas aeruginosa lung infection in rats.

METHODS

Plasmid-encoding rBD-2 was delivered to lungs in vivo using linear polyethylenimine at 48 h before challenging with seaweed alginate beads containing P. aeruginosa. Macroscopic and histopathological changes of the lungs, bacterial loads, inflammatory infiltration, and the levels of cytokines/chemokines [interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha, kertinocyte-derived chemokine (KC), macrophage inflammatory protein-2 (MIP-2)] were measured at 3 and 7 days post-infection (p.i.).

RESULTS

The overexpression of rBD-2 resulted in a significant increase in animal survival rate (at 3 days p.i.), a significant decrease in bacterial loads in the lungs (at 3 and 7 days p.i.), and significantly milder lung pathology. In addition, the overexpression of rBD-2 led to increased infiltration of polymorphonuclear neutrophils (PMN), and elevated protein expression of cytokines/chemokines (IL-1beta, TNF-alpha, KC and MIP-2) at the early stage of infection (at 3 days p.i.), at the same time as being dramatically decreased at the later stage of infection (at 7 days p.i.).

CONCLUSIONS

Genetic up-regulation of rBD-2 increased animal survival rate, and reduced bacterial loads in lungs after bacterial infection. The overexpression of rBD-2 also modulated the production of several cytokines/chemokines and increased PMN recruitment at the early stage of infection. Our findings indicate that the enhancement of BD-2 may be an efficacious intervention for chronic P. aeruginosa lung infection.

Predicting bacteremic pneumonia in HIV-1-infected patients consulting the ED

INTRODUCTION

HIV-1-infected patients have higher incidence of community-acquired pneumonia (CAP) and risk of complications. Bacteremia has been associated with a higher risk of complications in such patients. We investigated factors associated with bacteremia in HIV-1-infected patients with CAP presenting at the emergency department.

METHODS

We included HIV-1-infected patients with CAP for 3 years (March 2005-February 2008). Only patients in whom blood cultures were performed were finally included. Clinical data (age; sex; CD4(+) count; serum HIV viral load; previous or current intravenous drug use and antiretroviral treatment; systolic blood pressure; and cardiac and respiratory rates), analytical data (leukocyte count, arterial oxygen content, C-reactive protein value, and urgent Streptococcus pneumoniae and Legionella spp antigen urine detection), and APACHE-II (Acute Physiology and Chronic Health Evaluation) score were compiled. The need for intensive care unit admission, mechanical ventilation, mortality, and for patients finally discharged, duration of admission were retrospectively obtained from the clinical history. A multivariate analysis using logistic regression was performed to find independent predictors of bacteremia.

RESULTS

We diagnosed 129 HIV-1-infected patients with CAP. Blood cultures were performed in 118 cases (91%). Bacteremia was present in 28 (24%). Independent predictors of bacteremia were the detection of S pneumoniae antigen in urine (odds ratio, 9.0; 95% confidence interval, 1.9-42.0) and the absence of current antiretroviral treatment (odds ratio, 7.1; 95% confidence interval, 1.4-33.3). In-hospital mortality was higher in patients with bacteremia (15% vs 0%).

CONCLUSION

HIV-1-infected patients with CAP who are not on current antiretroviral therapy and have positive S pneumoniae antigenuria are at increased risk of having bacteremia. Bacteremic patients have a poor outcome.

Etiologies and outcome of acute respiratory failure in HIV-infected patients

Objective

To assess the etiologies and outcome of acute respiratory failure (ARF) in HIV-infected patients over the first decade of combination antiretroviral therapy (ART) use.

Methods

Retrospective study of all HIV-infected patients (n = 147) admitted to a single intensive care unit (ICU) for ARF between 1996 and 2006.

Results

ARF revealed the diagnosis of HIV infection in 43 (29.2%) patients. Causes of ARF were bacterial pneumonia (n = 74), Pneumocystis jirovecii pneumonia (PCP, n = 52), other opportunistic infections (n = 19), and noninfectious pulmonary disease (n = 33); the distribution of causes did not change over the 10-year study period. Two or more causes were identified in 33 patients. The 43 patients on ART more frequently had bacterial pneumonia and less frequently had opportunistic infections (P = 0.02). Noninvasive ventilation was needed in 49 patients and endotracheal intubation in 42. Hospital mortality was 19.7%. Factors independently associated with mortality were mechanical ventilation [odds ratio (OR) = 8.48, P < 0.0001], vasopressor use (OR, 4.48; P = 0.03), time from hospital admission to ICU admission (OR, 1.05 per day; P = 0.01), and number of causes (OR, 3.19; P = 0.02). HIV-related variables (CD4 count, viral load, and ART) were not associated with mortality.

Conclusion

Bacterial pneumonia and PCP remain the leading causes of ARF in HIV-infected patients in the ART era. Hospital survival has improved, and depends on the extent of organ dysfunction rather than on HIV-related characteristics.

[Characteristics of supposedly bacterial community acute pneumonia among HIV-positive patients: prospective preliminary study]

INTRODUCTION

Community-acquired pneumonia (CAP) is the second leading cause of hospitalization in the respirology department in Abidjan after tuberculosis. Frequently associated with HIV infection, it has a high mortality rate of about 20% to 30%. The aim of this study is to identify the specificities and severity factors associated with bacterial CAP (BCAP) outcome in HIV-positive patients.

METHODS

The authors conducted a prospective and comparative preliminary study on two groups of patients: 29 HIV-positive patients with BCAP and 21 HIV-negative patients with BCAP. All of the patients were hospitalized for BCAP with symptoms of severity according to the usual score of severity.

RESULTS

The sociodemographic, clinical and paraclinical characteristics were similar in both groups. Failures and deaths were more frequent in the group with HIV infection. In particular, HIV infected patients with a body mass index under 18.5 and a rate of T CD4 lymphocytes lower than 200/mm(3) presented the least favourable evolution.

CONCLUSIONS

A more extensive study should help define the appropriate severity criteria for BCAP associated with HIV infection.

Risk factors and outcome of community-acquired pneumonia due to Gram-negative bacilli

BACKGROUND AND OBJECTIVE

Several sets of guidelines have advocated initial antibiotic treatment for community-acquired pneumonia due to Gram-negative bacilli in patients with specific risk factors. However, evidence to support this recommendation is scarce. We sought to identify risk factors for community-acquired pneumonia due to Gram-negative bacilli, including Pseudomonas aeruginosa, and to assess outcomes.

METHODS

An observational analysis was carried out on prospectively collected data for immunocompetent adults hospitalized for community-acquired pneumonia in two acute-care hospitals. Cases of pneumonia due to Gram-negative bacilli were compared with those of non-Gram-negative bacilli causes.

RESULTS

Sixty-one (2%) of 3272 episodes of community-acquired pneumonia were due to Gram-negative bacilli. COPD (odds ratio (OR) 2.4, 95% confidence interval (CI): 1.2-5.1), current use of corticosteroids (OR 2.8, 95% CI: 1.2-6.3), prior antibiotic therapy (OR 2.6, 95% CI: 1.4-4.8), tachypnoea >or=30 cycles/min (OR 2.1, 95% CI: 1.1-4.2) and septic shock at presentation (OR 6.1, 95% CI: 2.5-14.6) were independently associated with Gram-negative bacilli pneumonia. Initial antibiotic therapy in patients with pneumonia due to Gram-negative bacilli was often inappropriate. These patients were also more likely to require admission to the intensive care unit, had longer hospital stays, and higher early (<48 h) (21% vs 2%; P < 0.001) and overall mortality (36% vs 7%; P < 0.001).

CONCLUSIONS

These results suggest that community-acquired pneumonia due to Gram-negative bacilli is uncommon, but is associated with a poor outcome. The risk factors identified in this study should be considered when selecting initial antibiotic therapy for patients with community-acquired pneumonia.

Benefit of antiretroviral therapy on survival of human immunodeficiency virus-infected patients admitted to an intensive care unit

OBJECTIVE

To evaluate the impact of antiretroviral therapy (ART) and the prognostic factors for in-intensive care unit (ICU) and 6-month mortality in human immunodeficiency virus (HIV)-infected patients.

DESIGN

A retrospective cohort study was conducted in patients admitted to the ICU from 1996 through 2006. The follow-up period extended for 6 months after ICU admission.

SETTING

The ICU of a tertiary-care teaching hospital at the Universidade de São Paulo, Brazil.

PARTICIPANTS

A total of 278 HIV-infected patients admitted to the ICU were selected. We excluded ICU readmissions (37), ICU admissions who stayed less than 24 hours (44), and patients with unavailable medical charts (36).

OUTCOME MEASURE

In-ICU and 6-month mortality.

MAIN RESULTS

Multivariate logistic regression analysis and Cox proportional hazards models demonstrated that the variables associated with in-ICU and 6-month mortality were sepsis as the cause of admission (odds ratio [OR] = 3.16 [95% confidence interval [CI] 1.65-6.06]); hazards ratio [HR] = 1.37 [95% CI 1.01-1.88]), an Acute Physiology and Chronic Health Evaluation II score >19 [OR = 2.81 (95% CI 1.57-5.04); HR = 2.18 (95% CI 1.62-2.94)], mechanical ventilation during the first 24 hours [OR = 3.92 (95% CI 2.20-6.96); HR = 2.25 (95% CI 1.65-3.07)], and year of ICU admission [OR = 0.90 (95% CI 0.81-0.99); HR = 0.92 [95% CI 0.87-0.97)]. CD4 T-cell count <50 cells/mm(3) was only associated with ICU mortality [OR = 2.10 (95% CI 1.17-3.76)]. The use of ART in the ICU was negatively predictive of 6-month mortality in the Cox model [HR = 0.50 (95% CI 0.35-0.71)], especially if this therapy was introduced during the first 4 days of admission to the ICU [HR = 0.58 (95% CI 0.41-0.83)]. Regarding HIV-infected patients admitted to ICU without using ART, those who have started this treatment during ICU stay presented a better prognosis when time and potential confounding factors were adjusted for [HR 0.55 (95% CI 0.31-0.98)].

CONCLUSIONS

The ICU outcome of HIV-infected patients seems to be dependent not only on acute illness severity, but also on the administration of antiretroviral treatment.

Trends in hospitalizations for AIDS-associated Pneumocystis jirovecii Pneumonia in the United States (1986 to 2005)

BACKGROUND

Although hospitalizations for AIDS-associated Pneumocystis jirovecii pneumonia (PCP) in the United States have decreased since the introduction of chemoprophylaxis and potent combination antiretroviral therapy (ART), PCP remains an important cause of illness and death among AIDS patients.

METHODS

We analyzed trends in AIDS-associated PCP hospital discharges using the National Hospital Discharge Surveys between 1986 and 2005.

RESULTS

An estimated 539 million patients were discharged from hospitals between 1986 and 2005, of whom an estimated 312,411 had AIDS-associated PCP. The proportion of patients discharged from the hospital with AIDS-associated PCP decreased from 31% before the introduction of chemoprophylaxis (1986 to 1989) to 17% with chemoprophylaxis (1990 to 1995) and subsequently to 9% after the introduction of ART in 1996 (p < 0.001). Mortality from AIDS-associated PCP decreased from 21 to 16% and subsequently to 7% between these three time periods (p < 0.001). Among those who received mechanical ventilation, mortality decreased from 79% in the prechemoprophylaxis era to 31% in the ART era (p < 0.001) alongside an increase (from 5 to 11%) in the use of mechanical ventilation. We also observed a shift in the population at-risk for PCP over time: a greater proportion of black people, women, and people from Southern states were affected (all p < 0.001).

CONCLUSIONS

While there have been significant reductions in hospitalizations and hospital mortality for AIDS-associated PCP over the last 20 years, these reductions have not been homogenous across demographic subpopulations and geographic regions and point to new at-risk populations. Furthermore, mortality in severe cases of PCP that require mechanical ventilation has improved substantially.

HIV-1-transgene expression in rats decreases alveolar macrophage zinc levels and phagocytosis

HIV-1 infection impairs alveolar macrophage immune function and renders patients susceptible to pneumonia by poorly understood mechanisms. Alveolar macrophage maturation and function depends on granulocyte-macrophage colony-stimulating factor (GM-CSF), which is produced and secreted by the alveolar epithelium. Macrophages respond to GM-CSF through the GM-CSF receptor (GM-CSFR), which has a binding subunit (GM-CSFRalpha) and a signaling subunit (GM-CSFRbeta). In this study, we measured GM-CSFR expression and alveolar macrophage function in a transgene HIV-1 rat model (NL4-3Delta gag/pol); this construct bears a pro-virus with gag and pol deleted, but other HIV-1-related proteins, such as gp120 and Tat, are expressed, and the rats develop an AIDS-like phenotype as they age. We first determined that HIV-1-transgenic expression selectively decreased alveolar macrophage expression of GM-CSFRbeta and impaired bacterial phagocytosis in vitro. Next, we examined the role of zinc (Zn) deficiency as a potential mechanism underlying these effects, and determined that HIV-1-transgenic rats have significantly lower levels of Zn in the alveolar space and macrophages. To test the direct effect of Zn deficiency on macrophage dysfunction, we treated rat alveolar macrophage cell line with a Zn chelator, N,N,N',N'-tetrakis-(2-pyridyl-methyl) ethylenediamine, and this decreased GM-CSFRbeta expression and phagocytosis. In parallel, treatment with Zn acetate in vitro for 48 hours restored intracellular Zn levels and phagocytic function in alveolar macrophages from HIV-1-transgenic rats. Taken together, these data suggest that pulmonary Zn deficiency could be one of the mechanisms by which chronic HIV-1 infection impairs alveolar macrophage immune function and renders these individuals susceptible to serious lung infections.

Bacterial induction of early response genes and activation of proapoptotic factors in pleural mesothelial cells

In bacterial empyema the pleural mesothelium is constantly exposed to microorganisms. Staphylococcus aureus (S. aureus) is one of the most frequent pathogens associated with empyema. In an earlier study we demonstrated that S. aureus induced barrier dysfunction in pleural mesothelial cell monolayers. In the present study we report that S. aureus activates the early response genes c-fos and c-jun and activator protein-1 (AP-1), and induces proapoptosis genes Bad and Bak in primary mouse pleural mesothelial cells (PMCs). Our data indicate that in PMCs S. aureus induces apoptosis in a time- and multiplicity of infection (MOI)-dependent manner. Staphylococcus aureus induced Bcl (2), Bcl-X (L), c-fos, c-jun, and AP-1 expression in PMCs during the initial phase of infection. In S. aureus-infected PMCs, Bad and Bak gene expression was increased and correlated with DNA fragmentation and cytochrome-c release. Bcl (2) and Bcl-X (L) gene expression was significantly lower in S. aureus-infected PMCs than in uninfected PMCs 12 h postinfection. We conclude that at the initial stage of infection S. aureus modulates expression of early response genes c-fos and c-jun, and in the late phase of infection S. aureus induces expression of proapoptotic genes Bak and Bad in PMCs. Silencing AP-1 significantly inhibited S. aureus-induced Bak and Bad expression in PMCs. The upregulation of early response genes during the early phase of infection may contribute to the activation of proapoptotic genes Bak and Bad and release of cytochrome-c, caspase-3 thereby resulting in apoptosis in PMCs.

Acute alcohol intoxication suppresses the pulmonary ELR-negative CXC chemokine response to lipopolysaccharide

Alcohol abuse impairs the pulmonary immune response to infection and increases the morbidity and mortality of bacterial pneumonia. Acute alcohol intoxication suppresses lung expression of CXC chemokines bearing the Glu-Leu-Arg motif (ELR+) following lipopolysaccharide (LPS) challenge, but its effect on the structurally related ELR- CXC chemokines, which attract T cells, is unknown. We therefore investigated the effect of acute alcohol intoxication on the pulmonary response to intratracheal (i.t.) LPS challenge for the ELR- CXC chemokines monokine induced by gamma (MIG or CXCL9), interferon-inducible protein 10 (IP-10 or CXCL10), and interferon-inducible T cell alpha chemoattractant (I-TAC or CXCL11). Male C57BL/6 or C3H/HeN mice were given an intraperitoneal injection of ethanol (3.0 g/kg) or phosphate buffered saline 30 min before i.t. LPS challenge. Chemokine mRNA transcripts were measured at 0, 2, 6, and 16 h. Acute alcohol intoxication inhibited the lung's expression of all three chemokine genes in response to LPS. Lung IFN-gamma mRNA was also inhibited by acute intoxication over the same time course. The in vitro effect of ethanol on chemokine secretion was further studied in the MH-S alveolar macrophage cell line. IP-10, MIG, and I-TAC in response to LPS were enhanced by exogenous interferon (IFN)-gamma, and these responses were blunted by exposure to ethanol. Alcohol exposure did not affect MH-S cell nuclear factor kappa beta p65 nuclear localization during challenge, despite dose-dependent inhibition of Erk 1/2 phosphorylation. In addition, phospho-signal transduction and activator of transcription 1 was not decreased in the presence of acute ethanol, thereby indicating that acute intoxication does not affect IFN-gamma signaling in MH-S cells. Recruitment of CD3+ T cells into the alveolar space 4 days after LPS challenge was moderately impaired by acute ethanol intoxication. These results implicate acute ethanol intoxication as a significant inhibitor of lymphocyte chemoattractant expression during pulmonary inflammation.

Bacteraemic pneumococcal pneumonia: Impact of HIV on clinical presentation and outcome

OBJECTIVES

The objectives of this study were to investigate the clinical and laboratory features, hospital course and outcome of patients with bacteraemic pneumococcal pneumonia, comparing HIV with non-HIV patients, as well as HIV patients from different parts of the world.

METHODS

This was a multicentre prospective observational study of consecutive adult cases with bacteraemic pneumococcal pneumonia in 10 countries on 6 continents.

RESULTS

A total of 768 cases were recruited, of which 200 were HIV-infected; 166 were from South Africa. Lower age, i.v. drug use, fewer co-morbid illnesses, and a higher frequency of respiratory symptoms were significantly more likely to occur in HIV patients. The 14-day mortality for the group as a whole was 14.5%, being 16% in the HIV patients and 13.9% in the non-HIV patients (not significant). When adjustments were made for age and severity of illness, HIV patients had significantly higher 14-day mortality with significant trend for increasing 14-day mortality in those with lower CD4 counts. Despite differences in various clinical and laboratory parameters in patients from different parts of the world, on multivariate analysis, when adjusting for regional differences, the HIV-infected patients were still noted to have poorer 14-day mortality.

CONCLUSIONS

This study, in contrast to previous investigations, indicates that there are significant differences in the clinical presentation and outcome of bacteraemic pneumococcal pneumonia when comparing HIV and non-HIV patients.