Atypical bacterial pneumonia in the HIV-infected population

Inflammatory Patterns Associated with Legionella in HIV and Pneumonia Coinfections

Legionella infections have a propensity for occurring in HIV-infected individuals, with immunosuppressed individuals tending to present with more severe disease. However, understanding regarding the Legionella host response in immune compromised individuals is lacking. This study investigated the inflammatory profiles associated with Legionella infection in patients hospitalized with HIV and pneumonia in Medellín, Colombia from February 2007 to April 2014, and correlated these profiles with clinical outcomes. Sample aliquots from the Colombian cohort were shipped to Canada where Legionella infections and systemic cytokine profiles were determined using real-time PCR and bead-based technology, respectively. To determine the effect of Legionella coinfection on clinical outcome, a patient database was consulted, comparing laboratory results and outcomes between Legionella-positive and -negative individuals. Principal component analysis revealed higher plasma concentrations of eotaxin, IP-10 and MCP-1 (p = 0.0046) during Legionella infection. Individuals with this immune profile also had higher rates of intensive care unit admissions (adjusted relative risk 1.047 [95% confidence interval 1.027-1.066]). Results demonstrate that systemic markers of monocyte/macrophage activation and differentiation (eotaxin, MCP-1, and IP-10) are associated with Legionella infection and worse patient outcomes. Further investigations are warranted to determine how this cytokine profile may play a role in Legionella pneumonia pathogenesis or immunity.

THE VALUE OF SERUM SEROMUCOID IN THE DIFFERENTIAL DIAGNOSIS OF BACTERIAL PNEUMONIA AND TUBERCULOSIS IN HIV-POSITIVE PATIENTS

OBJECTIVE

The aim: To optimize the differential diagnosis of bacterial pneumonia and tuberculosis in HIV-positive patients based on the value of serum seromucoid.

PATIENTS AND METHODS

Materials and methods: The study included 77 HIV-positive patients with lung pathology. The 1st group consisted of 44 HIV-infected patients with BP; the 2nd group - of 33 patients with HIV/TB co-infection. Level of SSM, CD4+ T-lymphocytes, HIV-1 RNA viral load was determined. Сlinical, laboratory, microscopic, radiological, microbiological, and statistical methods were used in the research.

RESULTS

Results: In patients with HIV/TB co-infection CD4+ T-lymphocyte level was lower, and viral load was higher than in HIV-infected patients with BP. The level of SSM was statistically significantly elevated in patients of both groups compared with the control (p<0,001), but in patients with HIV/TB co-infection the values were statistically significantly higher (p<0,001). In patients with BP, the content of SSM≤15,95 TU occurred statistically significantly more often than in patients with TB (χ2= 65,5; p <0,001). No statistically significant relationship between SSM content and CD4+ T-lymphocyte levels was found.

CONCLUSION

Conclusions: The content of SSM in patients with HIV/TB co-infection is statistically significantly higher than in the group of HIV-infected patients with BP. Determination of SSM level can be used as a rapid method of differential diagnosis of BP and TB in HIV-positive patients that will allow to optimize the diagnostic algorithm at the early stage of hospitalization and to receive the necessary timely treatment for HIV-infected patients.

Changes in causes of pregnancy-related and maternal mortality in Zimbabwe 2007-08 to 2018-19: findings from two reproductive age mortality surveys

Background

Reducing maternal mortality is a priority of Sustainable Development Goal 3.1 which requires frequent epidemiological analysis of trends and patterns of the causes of maternal deaths. We conducted two reproductive age mortality surveys to analyse the epidemiology of maternal mortality in Zimbabwe and analysed the changes in the causes of deaths between 2007-08 and 2018-19.

Methods

We performed a before and after analysis of the causes of death among women of reproductive ages (WRAs) (12-49 years), and pregnant women from the two surveys implemented in 11 districts, selected using multi-stage cluster sampling from each province of Zimbabwe (n=10); an additional district selected from Harare. We calculated mortality incidence rates and incidence rate ratios per 10000 WRAs and pregnant women (with 95% confidence intervals), in international classification of disease groups, using negative binomial models, and compared them between the two surveys. We also calculated maternal mortality ratios, per 100 000 live births, for selected causes of pregnancy-related deaths.

Results

We identified 6188 deaths among WRAs and 325 PRDs in 2007-08, and 1856 and 137 respectively in 2018-19. Mortality in the WRAs decreased by 82% in diseases of the respiratory system and 81% in certain infectious or parasitic diseases' groups, which include HIV/AIDS and malaria. Pregnancy-related deaths decreased by 84% in the indirect causes group and by 61% in the direct causes group, and HIV/AIDS-related deaths decreased by 91% in pregnant women. Direct causes of death still had a three-fold MMR than indirect causes (151 vs. 51 deaths per 100 000) in 2018-19.

Conclusion

Zimbabwe experienced a decline in both direct and indirect causes of pregnancy-related deaths. Deaths from indirect causes declined mainly due to a reduction in HIV/AIDS-related and malaria mortality, while deaths from direct causes declined because of a reduction in obstetric haemorrhage and pregnancy-related infections. Ongoing interventions ought to improve the coverage and quality of maternal care in Zimbabwe, to further reduce deaths from direct causes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-13321-7.

Pulmonary Immune Dysregulation and Viral Persistence During HIV Infection

Despite the success of antiretroviral therapy (ART), people living with HIV continue to suffer from high burdens of respiratory infections, lung cancers and chronic lung disease at a higher rate than the general population. The lung mucosa, a previously neglected HIV reservoir site, is of particular importance in this phenomenon. Because ART does not eliminate the virus, residual levels of HIV that remain in deep tissues lead to chronic immune activation and pulmonary inflammatory pathologies. In turn, continuous pulmonary and systemic inflammation cause immune cell exhaustion and pulmonary immune dysregulation, creating a pro-inflammatory environment ideal for HIV reservoir persistence. Moreover, smoking, gut and lung dysbiosis and co-infections further fuel the vicious cycle of residual viral replication which, in turn, contributes to inflammation and immune cell proliferation, further maintaining the HIV reservoir. Herein, we discuss the recent evidence supporting the notion that the lungs serve as an HIV viral reservoir. We will explore how smoking, changes in the microbiome, and common co-infections seen in PLWH contribute to HIV persistence, pulmonary immune dysregulation, and high rates of infectious and non-infectious lung disease among these individuals.

Mycoplasma pneumoniae Infections and Primary Immune Deficiencies

Mycoplasma pneumoniae (M. pneumoniae) is one of the leading causes of community-acquired pneumonia in children and is also implicated in a variety of reactive extrapulmonary diseases. Recurrent and/or severe respiratory infections are one of the most frequent manifestations of several types of primary immunodeficiency. Here, we reviewed the medical literature to assess the potential relevance of M. pneumoniae in the infections observed in children affected with combined, humoral, and innate primary immune deficiencies. M. pneumoniae does not result to be epidemiologically prevalent as a cause of pneumonia in children affected by primary immunodeficiencies, but this infection can have a persistent or severe course in this category of patients. Indeed, the active search of M. pneumoniae could be useful and appropriate especially in children with humoral immune deficiencies. Indeed, most cases of M. pneumoniae infection in primary immunodeficiencies are described in patients affected by a/hypo-gammaglobulinemia.

Assessment of evidence for or against contributions of Chlamydia pneumoniae infections to Alzheimer's disease etiology

Alzheimer's disease, the most common form of dementia, was first formally described in 1907 yet its etiology has remained elusive. Recent proposals that Aβ peptide may be part of the brain immune response have revived longstanding contention about the possibility of causal relationships between brain pathogens and Alzheimer's disease. Research has focused on infectious pathogens that may colonize the brain such as herpes simplex type I. Some researchers have proposed the respiratory bacteria Chlamydia pneumoniae may also be implicated in Alzheimer's disease, however this remains controversial. This review aims to provide a balanced overview of the current evidence and its limitations and future approaches that may resolve controversies. We discuss the evidence from in vitro, animal and human studies proposed to implicate Chlamydia pneumoniae in Alzheimer's disease and other neurological conditions, the potential mechanisms by which the bacterium may contribute to pathogenesis and limitations of previous studies that may explain the inconsistencies in the literature.

Treating bacterial pneumonia in people living with HIV

Introduction: Bacterial pneumonia remains an important cause of morbidity and mortality in people living with HIV (PLWH) in the antiretroviral therapy (ART) era. In addition to being immunocompromised, as reflected by low CD4 cell counts and elevated HIV viral loads, PLWH often have other behaviors associated with an increased risk of pneumonia including smoking and injected drug use. As PLWH are aging, comorbid conditions such as chronic obstructive pulmonary disease (COPD), cancers, and cardiovascular, renal and liver diseases are emerging as additional risk factors for pneumonia. Pathogens are often similar to those in HIV-uninfected individuals; however, PLWH are at risk for unusual and/or multi-drug resistant organisms causing bacterial pneumonia based, in part, on their CD4 cell counts and other exposures. Areas covered: In this review, we focus on the recognition and management of bacterial community-acquired pneumonia (CAP) in PLWH. Along with antimicrobial treatment, we discuss prevention strategies such as vaccination and smoking cessation. Expert opinion: Early initiation of ART after HIV infection can decrease the risk of pneumonia. Improved efforts at vaccination, smoking cessation, and reduction of other substance use are urgently needed in PLWH to decrease the risk for bacterial pneumonia. As PLWH are aging, comorbidities are additional risk factors for bacterial CAP.

Treating HIV-Positive/Non-AIDS Patients for Community-Acquired Pneumonia with ART

PURPOSE OF REVIEW

This article reviews the most recent publications on community-acquired pneumonia (CAP) in the HIV-infected population on antiretroviral therapy (ART), focusing on epidemiology, prognostic factors, etiology, and antimicrobial therapy. The data discussed here were mainly obtained from a non-systematic review using Medline and references from relevant articles.

RECENT FINDINGS

CAP remains a major cause of morbidity and mortality among HIV-infected patients and incurs high health costs despite the introduction of ART. HIV-infected patients are generally known to be more susceptible to bacterial pneumonia. Streptococcus pneumoniae is the most frequently reported pathogen in HIV-infected patients on ART, who present a higher rate of bacteremia than non-HIV-infected patients. Several studies have also examined microbial etiology and prognostic factors of CAP in HIV-infected patients on ART. Despite the high rate of bacterial pneumonia in these patients, mortality rates are not higher than in patients without HIV infection.

Community-acquired bacterial pneumonia in adult HIV-infected patients

INTRODUCTION

Despite active antiretroviral therapy (ART), community-acquired pneumonia (CAP) remains a major cause of morbidity and mortality among human immunodeficiency virus (HIV)-infected patients and incurs high health costs. Areas covered: This article reviews the most recent publications on bacterial CAP in the HIV-infected population, focusing on epidemiology, prognostic factors, microbial etiology, therapy, and prevention. The data discussed here were mainly obtained from a non-systematic review using Medline, and references from relevant articles. Expert commentary: HIV-infected patients are more susceptible to bacterial CAP. Although ART improves their immune response and has reduced CAP incidence, these patients continue to present increased risk of pneumonia in part because they show altered immunity and because immune activation persists. The risk of CAP in HIV-infected patients and the probability of polymicrobial or atypical infections are inversely associated with the CD4 cell count. Mortality in HIV-infected patients with CAP ranges from 6% to 15% but in well-controlled HIV-infected patients on ART the mortality is low and similar to that seen in HIV-negative individuals. Vaccination and smoking cessation are the two most important preventive strategies for bacterial CAP in well-controlled HIV-infected patients on ART.

Oral Chlamydia vaccination induces transmucosal protection in the airway

Although Chlamydia has been frequently detected in the gastrointestinal tracts of both humans and animals, it is not associated with any gastrointestinal pathology. We have recently shown that gastrointestinal Chlamydiamuridarum is not only non-pathogenic but also induces protective immunity in the genital tract. We now report that the transmucosal immunity induced by a single oral immunization with C.muridarum protected the mouse airway from a subsequent challenge infection. The oral immunization significantly reduced chlamydial burden in the airway as early as day 3 after intranasal challenge. As a result, the airway chlamydial spreading to extra-airway tissues was completely prevented on day 3 and significantly reduced on day 9. The immunized mice were protected from any significant systemic toxicity caused by the intranasal challenge since there was no significant bodyweight drop in the immunized mice. This robust protection correlated well with Chlamydia-specific antibodies that recognize chlamydial organism surface antigens and T cell responses that are dominated with a Th1 phenotype. The immunized mice developed high ratios of IgG2b/c over IgG1 levels and IFNγ-producing over IL-5- or IL-13-producing lymphocytes. Thus, we have demonstrated that oral vaccination with C. muridarum can induce Th1-dominant transmucosal immunity in the airway. Together with previous studies, we propose that non-pathogenic colonization of Chlamydia in the gastrointestinal tract be explored as an oral delivery system for inducing protection against infections and pathologies in extra-gastrointestinal tissues.