Immune aging and infectious diseases

ABSTRACT

The rise in global life expectancy has led to an increase in the older population, presenting significant challenges in managing infectious diseases. Aging affects the innate and adaptive immune systems, resulting in chronic low-grade inflammation (inflammaging) and immune function decline (immunosenescence). These changes would impair defense mechanisms, increase susceptibility to infections and reduce vaccine efficacy in older adults. Cellular senescence exacerbates these issues by releasing pro-inflammatory factors, further perpetuating chronic inflammation. Moreover, comorbidities, such as cardiovascular disease and diabetes, which are common in older adults, amplify immune dysfunction, while immunosuppressive medications further complicate responses to infections. This review explores the molecular and cellular mechanisms driving inflammaging and immunosenescence, focusing on genomic instability, telomere attrition, and mitochondrial dysfunction. Additionally, we discussed how aging-associated immune alterations influence responses to bacterial, viral, and parasitic infections and evaluated emerging antiaging strategies, aimed at mitigating these effects to improve health outcomes in the aging population.

Antibiotic susceptibility and phenotypic profile of Staphylococcus species isolated from different clinical samples from health facilities: A cross-sectional study

Background

Staphylococcus species are widely distributed in nature and found in various human body sites.

Objectives

To determine the antibiotic susceptibility pattern of Staphylococcus species isolated from different clinical samples.

Methods

This cross-sectional study was conducted on 400 clinical specimens from conveniently sampled patients seeking healthcare at two health facilities in sulaimani / Iraq. Bacterial isolation and identification were done using conventional techniques, after which the antibiotic susceptibility profile of Staphylococcus species commonly prescribed antibiotics used in treating infections at the facilities was done using the disc diffusion method. Finally, MecA, methicillin-resistant Staphylococcus aureus and macrolides-lincosamide and streptogramin genes with mupirocin-resistant, beta-lactamase and vancomycin-resistance phenotypes were identified.

Results

Staphylococcus aureus was the prevalent isolated species (n = 197, 49.3%), followed by Staphylococcus hemolyticus (n = 115, 28.8%), Staphylococcus epidermidis (n = 49, 12.3%), Staphylococcus hominis (n = 9.0, 2.3%), Staphylococcus sciuri (n = 8.0, 2.0%) and Staphylococcus lentus (n = 4.0, 1.0%). All isolated species resisted Penicillin G, Ampicillin, Cefotaxime and Cefoxitin. Most of the isolates, 89.5% (n = 358) had the beta-lactamase phenotype, 18.0% (n = 72) had the MecA gene, 2.8% (n = 11) the Mupirocin-resistant phenotype, and 2.0% (n = 8.0) the vancomycin-resistance phenotype. Additionally, 12 isolates had both methicillin-resistant Staphylococcus aureus (66.7%) and macrolides-lincosamide and streptogramin (65.2%) genes. The majority of the patients, 43% (n = 172) were >50 years old and 52.25% (n = 209) males. Also, most samples were from patients with urinary tract infection (n = 73), wound (n = 71), blood (n = 35), sputum (n = 29), pus (n = 28), seminal fluid (n = 27), cerebrospinal fluid (n = 1.0) and stool (n = 1.0). Most isolates that had the MSLb gene were highly significantly resistant to both Clindamycin (94.6%) and Erythromycin (84.7%) (p < 0.001).

Conclusions

Staphylococcus aureus was the predominant Staphylococcus species isolated from the clinical samples, most of which were resistant to most commonly prescribed antibiotics and had developed resistant genes and phenotypes.

Efficacy of seven and fourteen days of antibiotic treatment in uncomplicated Staphylococcus aureus bacteremia (SAB7): study protocol for a randomized controlled trial

Background

Staphylococcus aureus bacteremia (SAB) is frequently encountered in the hospital setting, and current guidelines recommend at least 14 days of antibiotic treatment for SAB in order to minimize risks of secondary deep infections and relapse. However, evidence to support these treatment recommendations remains scarce. Patients with uncomplicated SAB are known to have a low of risk of recurrence and death. Reducing treatment length in uncomplicated SAB would reduce the total consumption of antibiotics, duration of hospital admission, and potentially the risk of adverse events. With SAB7 we seek to determine if 7 days of antibiotic treatment in patients with uncomplicated SAB is non-inferior to 14 days of treatment.

Methods/design

The study is designed as a randomized, non-blinded, non-inferiority, multicenter interventional study. Primary measure of outcome will be 90-day survival without clinical or microbiological failure to treatment or relapse. Secondary outcomes include the prevalence of severe adverse effects, in particular secondary infection with Clostridium difficile, all-cause mortality, as well as public health related costs. Patients identified with uncomplicated SAB who have received 7 days of protocol-approved antibiotics will be eligible for inclusion and randomized 1:1 in two parallel arms to either (i) discontinue antibiotic treatment at day 7 or (ii) to continue antibiotic treatment for a total of 14 days. Main exclusion criteria include signs of complicated SAB, such as the presence of secondary deep infections, persistent bacteremia, and implantable devices. Patients are followed for 6 months with clinical examinations, consecutive blood tests, and registration of adverse events. A total of 284 patients are to be included at ten centers across Denmark. The primary endpoint will be tested with a statistical non-inferiority margin of 10 percentage points.

Discussion

SAB 7 will determine if 7 days of antibiotic treatment in patients with uncomplicated SAB is sufficient and safe. Results of the study will provide important knowledge on optimized SAB management and could potentially modify the current treatment recommendations.

Trial registration

ClinicalTrails.gov, H-17027414. Registered on May 2, 2018. The Danish Medicines Agency (EudraCT), 2017–003529-13. Registered on October 30, 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3357-9) contains supplementary material, which is available to authorized users.