Levofloxacin-ceftriaxone combination attenuates lung inflammation in a mouse model of bacteremic pneumonia caused by multidrug-resistant Streptococcus pneumoniae via inhibition of cytolytic activities of pneumolysin and autolysin

Factors Contributing to Chronic Kidney Disease following COVID-19 Diagnosis in Pre-Vaccinated Hospitalized Patients

In this study, we aim to evaluate the factors that may contribute to the development of chronic kidney disease following COVID-19 infection among hospitalized patients in two private hospitals in Jakarta, Indonesia. This is a retrospective cohort study between March 2020 and September 2021. Patient selection was conducted with a convenience sampling. All patients (n = 378) meeting the inclusion criteria during the study period were enrolled. Various sociodemographic, laboratory test, and diagnostic parameters were measured before the determination of their correlation with the outcome of COVID-19 infection. In this study, all pre-vaccinated patients with COVID-19 had no history of chronic kidney disease (CKD) prior to hospital admission. From this number, approximately 75.7% of the patients developed CKD following COVID-19 diagnosis. Overall, significant correlations were established between the clinical outcome and the CKD status (p = 0.001). Interestingly, there was a significant correlation between serum creatinine level, glomerular filtration rate (GFR), and CKD (p < 0.0001). Oxygen saturation (p = 0.03), admission to the intensive care unit (ICU) (p < 0.0001), and sepsis (p = 0.005) were factors that were significantly correlated with CKD status. Additionally, the type of antibiotic agent used was significantly correlated with CKD (p = 0.011). While 82.1% of patients with CKD survived, the survival rate worsened if the patients had complications from hyperuricemia (p = 0.010). The patients who received levofloxacin and ceftriaxone had the highest (100%) survival rate after approximately 50 days of treatment. The patients who received the antiviral agent combination isoprinosine + oseltamivir + ivermectin fared better (100%) as compared to those who received isoprinosine + favipiravir (8%). Factors, such as hyperuricemia and the antibiotic agent used, contributed to CKD following COVID-19 hospitalization. Interestingly, the patients who received levofloxacin + ceftriaxone and the patients without sepsis fared the best. Overall, patients who develop CKD following COVID-19 hospitalization have a low survival rate.

Pneumolysin as a target for new therapies against pneumococcal infections: A systematic review

BACKGROUND

This systematic review evaluates pneumolysin (PLY) as a target for new treatments against pneumococcal infections. Pneumolysin is one of the main virulence factors produced by all types of pneumococci. This toxin (53 kDa) is a highly conserved protein that binds to cholesterol in eukaryotic cells, forming pores that lead to cell destruction.

METHODS

The databases consulted were MEDLINE, Web of Science, and Scopus. Articles were independently screened by title, abstract, and full text by two researchers, and using consensus to resolve any disagreements that occurred. Articles in other languages different from English, patents, cases report, notes, chapter books and reviews were excluded. Searches were restricted to the years 2000 to 2021. Methodological quality was evaluated using OHAT framework.

RESULTS

Forty-one articles describing the effects of different molecules that inhibit PLY were reviewed. Briefly, the inhibitory molecules found were classified into three main groups: those exerting a direct effect by binding and/or blocking PLY, those acting indirectly by preventing its effects on host cells, and those whose mechanisms are unknown. Although many molecules are proposed as toxin blockers, only some of them, such as antibiotics, peptides, sterols, and statins, have the probability of being implemented as clinical treatment. In contrast, for other molecules, there are limited studies that demonstrate efficacy in animal models with sufficient reliability.

DISCUSSION

Most of the studies reviewed has a good level of confidence. However, one of the limitations of this systematic review is the lack of homogeneity of the studies, what prevented to carry out a statistical comparison of the results or meta-analysis.

CONCLUSION

A panel of molecules blocking PLY activity are associated with the improvement of the inflammatory process triggered by the pneumococcal infection. Some molecules have already been used in humans for other purposes, so they could be safe for use in patients with pneumococcal infections. These patients might benefit from a second line treatment during the initial stages of the infection preventing acute respiratory distress syndrome and invasive pneumococcal diseases. Additional research using the presented set of compounds might further improve the clinical management of these patients.

Streptococcus pneumoniae and Its Virulence Factors H2O2 and Pneumolysin Are Potent Mediators of the Acute Chest Syndrome in Sickle Cell Disease

Sickle cell disease (SCD) is one of the most common autosomal recessive disorders in the world. Due to functional asplenia, a dysfunctional antibody response, antibiotic drug resistance and poor response to immunization, SCD patients have impaired immunity. A leading cause of hospitalization and death in SCD patients is the acute chest syndrome (ACS). This complication is especially manifested upon infection of SCD patients with Streptococcus pneumoniae (Spn)—a facultative anaerobic Gram-positive bacterium that causes lower respiratory tract infections. Spn has developed increased rates of antibiotics resistance and is particularly virulent in SCD patients. The primary defense against Spn is the generation of reactive oxygen species (ROS) during the oxidative burst of neutrophils and macrophages. Paradoxically, Spn itself produces high levels of the ROS hydrogen peroxide (H₂O₂) as a virulence strategy. Apart from H₂O₂, Spn also secretes another virulence factor, i.e., the pore-forming exotoxin pneumolysin (PLY), a potent mediator of lung injury in patients with pneumonia in general and particularly in those with SCD. PLY is released early on in infection either by autolysis or bacterial lysis following the treatment with antibiotics and has a broad range of biological activities. This review will discuss recent findings on the role of pneumococci in ACS pathogenesis and on strategies to counteract the devastating effects of its virulence factors on the lungs in SCD patients.

C-Reactive Protein-Based Strategy to Reduce Antibiotic Dosing for the Treatment of Pneumococcal Infection

C-reactive protein (CRP) is a component of innate immunity. The concentration of CRP in serum increases in microbial infections including Streptococcus pneumoniae infection. Employing a mouse model of pneumococcal infection, it has been shown that passively administered human wild-type CRP protects mice against infection, provided that CRP is injected into mice within two hours of administering pneumococci. Engineered CRP (E-CRP) molecules have been reported recently; unlike wild-type CRP, passively administered E-CRP protected mice against infection even when E-CRP was injected into mice after twelve hours of administering pneumococci. The current study was aimed at comparing the protective capacity of E-CRP with that of an antibiotic clarithromycin. We established a mouse model of pneumococcal infection in which both E-CRP and clarithromycin, when used alone, provided minimal but equal protection against infection. In this model, the combination of E-CRP and clarithromycin drastically reduced bacteremia and increased survival of mice when compared to the protective effects of either E-CRP or clarithromycin alone. E-CRP was more effective in reducing bacteremia in mice treated with clarithromycin than in untreated mice. Also, there was 90% reduction in antibiotic dosing by including E-CRP in the antibiotic-treatment for maximal protection of infected mice. These findings provide an example of cooperation between the innate immune system and molecules that prevent multiplication of bacteria, and that should be exploited to develop novel combination therapies for infections against multidrug-resistant pneumococci. The reduction in antibiotic dosing by including E-CRP in the combination therapy might also resolve the problem of developing antibiotic resistance.

Clinically relevant model of pneumococcal pneumonia, ARDS, and nonpulmonary organ dysfunction in mice

Pneumonia is responsible for more deaths in the United States than any other infectious disease. Severe pneumonia is a common cause of acute respiratory failure and acute respiratory distress syndrome (ARDS). Despite the introduction of effective antibiotics and intensive supportive care in the 20th century, death rates from community-acquired pneumonia among patients in the intensive care unit remain as high as 35%. Beyond antimicrobial treatment, no targeted molecular therapies have yet proven effective, highlighting the need for additional research. Despite some limitations, small animal models of pneumonia and the mechanistic insights they produce are likely to continue to play an important role in generating new therapeutic targets. Here we describe the development of an innovative mouse model of pneumococcal pneumonia developed for enhanced clinical relevance. We first reviewed the literature of small animal models of bacterial pneumonia that incorporated antibiotics. We then did a series of experiments in mice in which we systematically varied the pneumococcal inoculum and the timing of antibiotics while measuring systemic and lung-specific end points, producing a range of models that mirrors the spectrum of pneumococcal lung disease in patients, from mild self-resolving infection to severe pneumonia refractory to antibiotics. A delay in antibiotic treatment resulted in ongoing inflammation and renal and hepatic dysfunction despite effective bacterial killing. The addition of fluid resuscitation to the model improved renal function but worsened the severity of lung injury based on direct measurements of pulmonary edema and lung compliance, analogous to patients with pneumonia and sepsis who develop ARDS following fluid administration.

Аrginase/NO-synthase system сharacteristics in blood lymphocytes under effect of fluoroquinolones

Antibiotics of the fluoroquinolone series are highly effective synthetic drugs of a wide range of antimicrobial activity. They have a specific mechanism of action on bacterial cells to inhibit the DNA-gyrase enzyme of mostly gram-negative and the topoisomerase IV of gram-positive bacterial cells, which leads to a decrease in the activity of enzymes, disruption of DNA and RNA biosyntheses, and the impossibility of chromosome superspilarization, as a result of which its division is broken and the cell dies. Fluoroquinolones also have an immunomodulatory effect, which is very important in terms of the pathogenesis of many infectious and inflammatory diseases. We assume that fluoroquinolones also act on cells of the body of patients, in particular on such regulatory mechanisms as the arginase-NO-synthase system. In this regard, peripheral blood lymphocytes can be a convenient and adequate model for studying the mechanism of the effect of fluoroquinolones. It is shown that under the influence of various generations of fluoroquinolones, arginase activity increases, depending on the dose, in the following sequence: control → ciprofloxacin → levofloxacin → moxifloxacin. The highest activity is observed under the effects of moxifloxacin, belonging to generation IV. The increase in arginase activity in blood lymphocytes under the influence of fluoroquinolones occurs due to the growth of turnover number of the enzymes (Vmax increases), although the affinity of enzyme to the substrate decreases (KL-arg increases). At the same time, all fluoroquinolones reduce the activity of the constitutive isoforms of NO-synthase, depending on the dose. It has been established that a slight activity of iNOS of blood lymphocytes in practically healthy women was detected, almost on the verge of error. When studying the influence of fluoroquinolones on the activation of iNOS lymphocytes isolated from the blood of practically healthy women, we did not observe its activity, and the inhibitive effect could not be determined due to its low activity. Oxidative stress was used to induce iNOS activity in blood lymphocytes, with H2O2 lymphocytes preincubation. The preincubation of lymphocytes with 0.2 mM H2O2 leads to increase of iNOS activity by 31.30 times. By activation of iNOS with hydrogen peroxide, 10–5 M concentration of ciprofloxin leads to inhibition of enzyme activity by 1.22 times, levofloxacin by 1.45 and moxifloxacin by 2.34 times. The obtained kinetic parameters suggest that in the blood lymphocytes under the influence of fluoroquinolones, the synthesis of NO with the participation of cNOS is inhibited, and the hyperproduction of NO is inhibited by the activation of iNOS, which is characteristic for pathological conditions.

Mechanism of Macrolide-Induced Inhibition of Pneumolysin Release Involves Impairment of Autolysin Release in Macrolide-Resistant Streptococcus pneumoniae

Streptococcus pneumoniae is a leading cause of community-acquired pneumonia. Over the past 2 decades, macrolide resistance among S. pneumoniae organisms has been increasing steadily and has escalated at an alarming rate worldwide. However, the use of macrolides in the treatment of community-acquired pneumonia has been reported to be effective regardless of the antibiotic susceptibility of the causative pneumococci. Although previous studies suggested that sub-MICs of macrolides inhibit the production of the pneumococcal pore-forming toxin pneumolysin by macrolide-resistant S. pneumoniae (MRSP), the underlying mechanisms of the inhibitory effect have not been fully elucidated. Here, we show that the release of pneumococcal autolysin, which promotes cell lysis and the release of pneumolysin, was inhibited by treatment with azithromycin and erythromycin, whereas replenishing with recombinant autolysin restored the release of pneumolysin from MRSP. Additionally, macrolides significantly downregulated ply transcription followed by a slight decrease of the intracellular pneumolysin level. These findings suggest the mechanisms involved in the inhibition of pneumolysin in MRSP, which may provide an additional explanation for the benefits of macrolides on the outcome of treatment for pneumococcal diseases.

Ozone therapy ameliorates inflammation and endometrial injury in rats with pelvic inflammatory disease

As a common cause of infertility, pelvic inflammatory disease (PID) is characterized by chronic pain, ectopic pregnancy as well as inflammation and infection of the female upper genital tract. Ozone water, also known as O_3, has been previously reported to be a distinctly effective agent in treating inflammation. During the present study, we asserted the hypothesis that O₃ could be applied by pelvic inflammation and works to regulate the expression of inflammatory factors including interleukin-6 (IL-6), IL-2 and tumor necrosis factor-α (TNF-α). In an attempt to evaluate the effect of O₃ on PID, an acute PID rat model was subsequently established. O₃ at concentrations of 45 μg/mL and 60 μg/mL in addition to levofloxacin (LVLX) was injected respectively into the PID rats in a bid to alter the contents of inflammatory factors and immunologic markers. Hematoxylin-eosin (HE) staining was applied to analyze endometrial inflammation. Reductions to the contents of IL-6 and TNF-α were recorded, while that of IL-2, IgA, IgG, IgM, C3 and C4, and E rosette formation rate and transformation rate of T lymphocytes exhibited notably elevated levels after the PID rats had been injected with 45 μg/mL O₃, 60 μg/mL O₃ or LVLX. The pathological condition of the endometrium in rats with PID was alleviated among the PID rats after injected with the 45 μg/mL O₃, 60 μg/mL O₃ or LVLX. Taken together, the key findings of the current study present evidence demonstrating that the administration of O₃ to the pelvic cavity ameliorated the PID conditions among rat models via inhibition of the necrosis of the endometrial epithelial cells as well as alleviated the inflammatory reactions, highlighting a potential novel PID treatment target.

Dauricine combined with clindamycin inhibits severe pneumonia co-infected by influenza virus H5N1 and Streptococcus pneumoniae in vitro and in vivo through NF-κB signaling pathway

Dauricine, isolated from Menispermum dauricum, has been widely used for treatment of various diseases, including cardiac ischemia and inflammation-related diseases. However, little is known regarding to the effect of dauricine on severe pneumonia. Therefore, the aim was to investigate the effect of dauricine on severe pneumonia and its mechanism during progress. Herein, H5N1 and Streptococcus pneumoniae (D39) were conducted to induce severe pneumonia in both BEAS-2B cells and mice. In vitro, dauricine reversed the protein and mRNA expressions of TNF-α, IL-6 and IL-1β, examined by ELISA and qRT-PCR assay, respectively. In addition, the nuclear translocation of NF-κB/p65 and the phosphorylation expressions of IκBα and IKKα/β, examined by western blotting, were dose-dependently dropped by dauricine. However, dauricine had no significant effect on MAPKs, including JNK, ERK and p38. In vivo, dauricine significantly decreased MPO activity, the lung wet/dry weight ratio, the protein and mRNA expression of TNF-α, IL-6 and IL-1β, the expressions of NF-κB/p65, and attenuated the lung histological alterations. Besides, compared to dauricine alone, combined with clindamycin had more remarkably effects on severe pneumonia in vitro. Overall, the results suggested that dauricine, a relatively drug that targets NF-κB, in combination with clindamycin, maybe a novel therapeutic strategy for severe pneumonia.

Effectiveness of combination therapy versus monotherapy with a third-generation cephalosporin in bacteraemic pneumococcal pneumonia: A propensity score analysis

OBJECTIVE

Combining a macrolide or a fluoroquinolone to beta-lactam regimens in the treatment of patients with moderate to severe community-acquired pneumonia is recommended by the international guidelines. However, the information in patients with bacteraemic pneumococcal pneumonia is limited.

METHODS

A propensity score technique was used to analyze prospectively collected data from all patients with bacteraemic pneumococcal pneumonia admitted from 2000 to 2015 in our institution, who had received empirical treatment with third-generation cephalosporin in monotherapy or plus macrolide or fluoroquinolone.

RESULTS

We included 69 patients in the monotherapy group and 314 in the combination group. After adjustment by PS for receiving monotherapy, 30-day mortality (OR 2.89; 95% CI 1.07-7.84) was significantly higher in monotherapy group. A higher 30-day mortality was observed in monotherapy group in both 1:1 and 1:2 matched samples although it was statistically significant only in 1:2 sample (OR: 3.50 (95% CI 1.03-11.96), P = 0.046).

CONCLUSIONS

Our study suggests that in bacteraemic pneumococcal pneumonia, empirical therapy with a third-generation cephalosporin plus a macrolide or a fluoroquinolone is associated with a lower mortality rate than beta-lactams in monotherapy. These results support the recommendation of combination therapy in patients requiring admission with moderate to severe disease.

Lethal Synergism between Influenza and Streptococcus pneumoniae

The devastating synergism of bacterial pneumonia with influenza viral infections left its mark on the world over the last century. Although the details of pathogenesis remain unclear, the synergism is related to a variety of factors including pulmonary epithelial barrier damage which exposes receptors that influence bacterial adherence and the triggering of an exaggerated innate immune response and cytokine storm, which further acts to worsen the injury. Several therapeutics and combination therapies of antibiotics, anti-inflammatories including corticosteroids and toll-like receptor modifiers, and anti-virals are being discussed. This mini review summarizes recent developments in unearthing the pathogenesis of the lethal synergism of pneumococcal co-infection following influenza, as well as addresses potential therapeutic options and combinations of therapies currently being evaluated.