Biology subjects

Salazar, K. C.

Publications and source records attributed to Salazar, K. C..

3 recordsLinked to original sources

bioRxiv2025

Cytokine and Immunoglobulin Dynamics in Phage Therapy: Insights from Clinical Cases

BackgroundBacteriophage therapy is increasingly used for antibiotic-refractory infections, yet its immunologic effects in humans remain poorly defined. We evaluated cytokine and immunoglobulin responses in nine compassionate-use cases of intravenous phage therapy, including solid organ transplant recipients and patients with device-associated or refractory bacterial infections. MethodsSerial serum samples were analyzed by multiplex Luminex immunology and isotyping assays, with results correlated to host immune status, infecting organism, and clinical outcome. ResultsCytokine patterns were heterogeneous and appeared to reflect the infecting pathogen more than phage exposure. Pseudomonas aeruginosa infections elicited broad pro-inflammatory cytokine increases (notably MCP-3 and TNF-{beta}), while Staphylococcus aureus infection was associated with overall cytokine reduction except for IL-6. Most immunocompetent patients exhibited an early IgM response within 1-2 weeks of phage initiation, whereas immunocompromised hosts demonstrated attenuated antibody levels. Neither cytokine nor humoral responses correlated with clinical outcome. In one case, serum neutralization developed against a specific phage but not against a subsequent, distinct phage cocktail targeting the same organism, suggesting variability in phage immunogenicity. ConclusionOverall, intravenous phage therapy frequently induces IgM responses, which are more pronounced in immunocompetent patients, while cytokine dynamics depend more on pathogen and immune status than on phage administration itself. These findings underscore the need for standardized immune profiling in clinical phage trials to delineate beneficial versus detrimental immune responses and to inform the design of phage formulations with optimized immunogenic profiles.

microbiology↗

bioRxiv2025

Pathogen-Phage Geomapping to Overcome Resistance

The rise of antibiotic resistance has renewed interest in bacteriophages as therapeutic alternatives. However, co-evolution of phage and bacteria will naturally give rise to phage-resistant pathogens, complicating phage therapy efforts. A critical bottleneck in the production of phage therapeutics is the discovery of virulent phages against resistant pathogens. Conventional methods for discovery are time-consuming, biased, and laborious, limiting the potential for identifying suitable phage candidates. To overcome these limitations, we combined small-volume environmental sampling with 16S rRNA sequencing to identify reservoirs where bacterial hosts co-exist with their phage predators. This strategy, which we term geographical phage mapping (ge{Phi}mapping), pinpoints ecological "hotspots" for targeted phage hunting. We further developed a portable phage hunting device ({Phi}HD) that generates highly enriched phage concentrates directly from these reservoirs. By integrating ge{Phi}mapping with high-throughput enrichment, we constructed the R{Phi} library, a diverse collection of novel phages. We captured and isolated 36 new phages targeting extremely-resistant organisms across various ESKAPE pathogens when conventional phage hunting and experimental evolution approaches failed.

microbiology↗

bioRxiv2020

Phage-Antibiotic Synergy Is Driven By A Unique Combination Of Antibacterial Mechanism Of Action And Stoichiometry

The continued rise in antibiotic resistance is precipitating a medical crisis. Bacteriophage (phage) has been hailed as one possible therapeutic option to augment the efficacy of antibiotics. However, only a handful of studies have addressed the synergistic relationship between phage and antibiotics. Here, we report a comprehensive analysis of phage-antibiotic interaction that evaluates synergism, additivism, and antagonism for all classes of antibiotics across clinically achievable stoichiometries. We combined an optically-based real-time microtiter plate readout with a matrix-like heatmap of treatment potencies to measure phage and antibiotic synergy (PAS), a process we term synography. Phage-antibiotic synography was performed against a pandemic drug-resistant clonal group of E. coli (ExPEC) with antibiotic levels blanketing the minimum inhibitor concentration (MIC) across seven orders of viral titers. Our results suggest that, under certain conditions, phages provide an adjuvating effect by lowering the MIC for drug-resistant strains. Furthermore, synergistic and antagonistic interactions are highly dependent on the mechanism of bacterial inhibition by the class of antibiotic paired to the phage, and when synergism is observed, it suppresses the emergence of resistant cells. Host conditions that simulate the infection environment, including serum and urine, suppress PAS in a bacterial growth-dependent manner. Lastly, phage burst size seems to be a significant driver of synergism. Collectively, this data suggests lytic phages can resuscitate an ineffective antibiotic for previously resistant bacteria, while also synergize with antibiotics in a class-dependent manner, processes that may be dampened by lower bacterial growth rates found in host environments. Significance StatementBacteriophage (phage) therapy is a promising approach to combat the rise of multi-drug resistant bacteria. Currently, the preferred clinical modality is to pair phage with an antibiotic, a practice thought to improve efficacy. However, antagonism between phage and antibiotics has been reported, the choice of phage and antibiotic is not often empirically determined, and the effect of the host factors on the effectiveness is unknown. Here, we interrogate phage-antibiotic interactions across antibiotics with different mechanisms of action. Our results suggest that phage can lower the working MIC for bacterial strains already resistant to the antibiotic, is dependent on the antibiotic class and stoichiometry of the pairing, and is dramatically influenced by the host microenvironment.

microbiology↗