Phages for Africa: The Potential Benefit and Challenges of Phage Therapy for the Livestock Sector in Sub-Saharan Africa

Novel Escherichia coli-Infecting Bacteriophages Isolated from Uganda That Target Human Clinical Isolates

Background

The antimicrobial resistance catastrophe is a growing global health threat and predicted to be worse in developing countries. Phages for Global Health (PGH) is training scientists in these regions to isolate relevant therapeutic phages for pathogenic bacteria within their locality, and thus contributing to making phage technology universally available.

Materials and Methods

During the inaugural PGH workshop in East Africa, samples from Ugandan municipal sewage facilities were collected and two novel Escherichia coli lytic phages were isolated and characterized.

Results

The phages, UP19 (capsid diameter ∼100 nm, contractile tail ∼120/20 nm) and UP30 (capsid diameter ∼70 nm, noncontractile tail of ∼170/20 nm), lysed ∼82% and ∼36% of the 11 clinical isolates examined, respectively. The genomes of UP19 (171.402 kb, 282 CDS) and UP30 (49.834 kb, 75 CDS) closely match the genera Dhakavirus and Tunavirus, respectively.

Conclusion

The phages isolated have therapeutic potential for further development against E. coli infections.

Bacteriophage Therapy to Control Bovine Mastitis: A Review

Bovine mastitis is a polymicrobial disease characterised by inflammation of the udders of dairy and beef cattle. The infection has huge implications to health and welfare of animals, impacting milk and beef production and costing up to EUR 32 billion annually to the dairy industry, globally. Bacterial communities associated with the disease include representative species from Staphylococcus, Streptococcus, Enterococcus, Actinomyces, Aerococcus, Escherichia, Klebsiella and Proteus. Conventional treatment relies on antibiotics, but antimicrobial resistance, declining antibiotic innovations and biofilm production negatively impact therapeutic efficacy. Bacteriophages (phages) are viruses which effectively target and lyse bacteria with extreme specificity and can be a valuable supplement or replacement to antibiotics for bovine mastitis. In this review, we provide an overview of the etiology of bovine mastitis, the advantages of phage therapy over chemical antibiotics for the strains and research work conducted in the area in various model systems to support phage deployment in the dairy industry. We emphasise work on phage isolation procedures from samples obtained from mastitic and non-mastitic sources, characterisation and efficacy testing of single and multiple phages as standalone treatments or adjuncts to probiotics in various in vitro, ex vivo and in vivo bovine mastitis infection models. Furthermore, we highlight the areas where improvements can be made with focus on phage cocktail optimisation, formulation, and genetic engineering to improve delivery, stability, efficacy, and safety in cattle. Phage therapy is becoming more attractive in clinical medicine and agriculture and thus, could mitigate the impending catastrophe of antimicrobial resistance in the dairy sector.

Phages for the treatment of Mycobacterium species

Highly drug-resistant strains are not uncommon among the Mycobacterium genus, with patients requiring lengthy antibiotic treatment regimens with multiple drugs and harmful side effects. This alarming increase in antibiotic resistance globally has renewed the interest in mycobacteriophage therapy for both Mycobacterium tuberculosis complex and non-tuberculosis mycobacteria. With the increasing number of genetically well-characterized mycobacteriophages and robust engineering tools to convert temperate phages to obligate lytic phages, the phage cache against extensive drug-resistant mycobacteria is constantly expanding. Synergistic effects between phages and TB drugs are also a promising avenue to research, with mycobacteriophages having several additional advantages compared to traditional antibiotics due to their different modes of action. These advantages include less side effects, a narrow host spectrum, biofilm penetration, self-replication at the site of infection and the potential to be manufactured on a large scale. In addition, mycobacteriophage enzymes, not yet in clinical use, warrant further studies with their additional benefits for rupturing host bacteria thereby limiting resistance development as well as showing promise in vitro to act synergistically with TB drugs. Before mycobacteriophage therapy can be envisioned as part of routine care, several obstacles must be overcome to translate in vitro work into clinical practice. Strategies to target intracellular bacteria and selecting phage cocktails to limit cross-resistance remain important avenues to explore. However, insight into pathophysiological host-phage interactions on a molecular level and innovative solutions to transcend mycobacteriophage therapy impediments, offer sufficient encouragement to explore phage therapy. Recently, the first successful clinical studies were performed using a mycobacteriophage-constructed cocktail to treat non-tuberculosis mycobacteria, providing substantial insight into lessons learned and potential pitfalls to avoid in order to ensure favorable outcomes. However, due to mycobacterium strain variation, mycobacteriophage therapy remains personalized, only being utilized in compassionate care cases until there is further regulatory approval. Therefore, identifying the determinants that influence clinical outcomes that can expand the repertoire of mycobacteriophages for therapeutic benefit, remains key for their future application.

Current Clinical Landscape and Global Potential of Bacteriophage Therapy

In response to the global spread of antimicrobial resistance, there is an increased demand for novel and innovative antimicrobials. Bacteriophages have been known for their potential clinical utility in lysing bacteria for almost a century. Social pressures and the concomitant introduction of antibiotics in the mid-1900s hindered the widespread adoption of these naturally occurring bactericides. Recently, however, phage therapy has re-emerged as a promising strategy for combatting antimicrobial resistance. A unique mechanism of action and cost-effective production promotes phages as an ideal solution for addressing antibiotic-resistant bacterial infections, particularly in lower- and middle-income countries. As the number of phage-related research labs worldwide continues to grow, it will be increasingly important to encourage the expansion of well-developed clinical trials, the standardization of the production and storage of phage cocktails, and the advancement of international collaboration. In this review, we discuss the history, benefits, and limitations of bacteriophage research and its current role in the setting of addressing antimicrobial resistance with a specific focus on active clinical trials and case reports of phage therapy administration.

Alternatives to Antimicrobial Treatment in Bovine Mastitis Therapy: A Review

Despite preventive and therapeutic measures, mastitis continues to be the most prevalent health problem in dairy herds. Considering the risks associated with antibiotic therapy, such as compromised effectiveness due to the emergence of resistant bacteria, food safety issues, and environmental impact, an increasing number of scientific studies have referred to the new therapeutic procedures that could serve as alternatives to conventional therapy. Therefore, the aim of this review was to provide insight into the currently available literature data in the investigation of non-antibiotic alternative approaches. In general, a vast number of in vitro and in vivo available data offer the comprehension of novel, effective, and safe agents with the potential to reduce the current use of antibiotics and increase animal productivity and environmental protection. Constant progress in this field could overcome treatment difficulties associated with bovine mastitis and considerable global pressure being applied on reducing antimicrobial therapy in animals.

Gender-Responsive Design of Bacteriophage Products to Enhance Adoption by Chicken Keepers in Kenya

Women and men keeping chickens in Kenya aspire to have a source of income, feed their families healthy food, and grow their businesses. Managing animal diseases and minimizing input costs enable their success. This study uses qualitative methods to recommend design opportunities for a veterinary product under development in Kenya that contains bacteriophages (phages) that target pathogenic Salmonella strains responsible for fowl typhoid, salmonellosis, and pullorum in chickens and foodborne illness in people. Our findings revealed the interplay between gender and two production systems: free-range and semi-intensive. Chicken keepers in both systems could benefit from phages combined with the orally administered Newcastle disease vaccine, one of the most commonly used preventive veterinary interventions, or phages as a treatment for fowl typhoid. Oral administration is less labor intensive, with greater benefits for women who have less control over family labor and reported doing more care tasks themselves. Men in free-range systems usually pay for veterinary inputs. In semi-intensive production systems, a phage-based product used prophylactically could be an alternative to expensive, intramuscular fowl typhoid vaccines. Keeping layers was common for women in semi-intensive systems, as they are more economically impacted by reduced laying caused by bacterial diseases. Awareness of zoonoses was low, but men and women were concerned about the negative health effects of drug residues in meat and eggs. Therefore, highlighting the lack of a withdrawal period for a phage product may appeal to customers. Antibiotics are used to both treat and prevent diseases, and phage products will need to do both to compete in the Kenyan market. These findings guide the ongoing design of a phage-based product with the goal of introducing a new veterinary product that meets the diverse needs of chicken keepers in Africa and serves as an alternative or complement to antibiotics.

Formulation of phage cocktails and evaluation of their interaction with antibiotics in inhibiting carbapenemase-producing Klebsiella pneumoniae in vitro in Kenya

Background: The development of alternative control measures, such as phage therapy or adjunctive therapy, is urgently needed to manage the dissemination of carbapenemase-producing Klebsiella pneumoniae.Objective: This study aimed to evaluate the therapeutic potential of formulated phage cocktails and their interaction with select antibiotics in inhibiting the growth of carbapenemase-producing K. pneumoniae clinical isolate in vitro in Kenya.Methods: The study was conducted from February 2021 to October 2021 at the Institute of Primate Research, Nairobi, Kenya. Phage cocktails were formulated based on the morphology and biological properties of precipitated Klebsiella phages. The efficacy of individual bacteriophages and phage cocktails as well as their combination with antibiotics were determined for their inhibitory activity on carbapenemase-producing K. pneumoniae (KP20).Results: The precipitated bacteriophages were members of Myoviridae, Siphoviridae and Podoviridae. Regarding the evaluation of the phage cocktails, the absorbances at 600 nm of the bacterial culture treated with the two-phage cocktail (2φ MA) ranged from 0.173 to 0.246 at 16 h and 20 h whereas it peaked from 2.116 to 2.190 for the positive control. Moreover, the results of the adjunctive therapy showed that the optical density at 600 nm of the bacterial culture treated with 2φ MA was 0.186 at 24 h post-incubation time while it was 0.099 with the bacterial culture treated with imipenem in combination with 2φ MA.Conclusion: This study demonstrated that the two-phage cocktail in combination with imipenem was able to synergistically delay the increase in carbapenemase-producing K. pneumoniae growth in vitro.

Treating bacterial infections with bacteriophages in the 21st century

Bacteriophages (phages) were discovered in the early part of the 20th century, and their ability to eliminate bacterial infections as bacterial viruses gathered interest almost immediately. Bacteriophage therapy was halted in the Western world due to inconclusive results in early experiments and the concurrent discovery of antibiotics. The spread of antibiotic-resistant bacteria has elicited renewed interest in bacteriophages as a natural alternative to conventional antibiotic therapy. Interest in the application of bacteriophages has also expanded to include the environment, such as wastewater treatment, agriculture and aquaculture. Although the complete phage is important in bacteriophage therapy, the focus is shifting to purified phage enzymes. These enzymes are an attractive option for pharmaceutical companies with their patent potential. They can be bio-engineered for enhanced adjuvant properties, such as a broadened spectrum of activity or binding capability. Enzymes also eliminate the concern that the prophage might integrate resistance genes into the bacterial genome. From a clinical perspective, the first randomised clinical controlled phage therapy trial was conducted with more pioneering phase I/II clinical studies on the horizon. In this opinion paper, the authors outline bacteriophages as naturally occurring bactericidal entities, their therapeutic potential against antibiotic-resistant bacteria and compare them to antibiotics. Their potential multipurpose application in the medical field is also addressed, including the use of bacteriophages for vaccination, and utilisation of the antimicrobial enzymes that they produce.

Prospects of bacteriophage collections in disinfectant applications

Background and Aim:

The search and development of disinfectants is promising worldwide. However, there are currently no international regulations governing the testing and registration of germicidal agents. Moreover, the number of safety requirements for disinfectants for human, animal, and environmental health has increased. This research aimed to evaluate the prospects of using a collection of bacteriophages for disinfectant purposes.

Materials and Methods:

The objects of research were bacteriophages isolated from a total of 129 environmental samples obtained from seven sources in and around livestock buildings: (1) Feed residues from feeders and automatic drinkers; (2) washouts from floors, walls, and posts; (3) soil from underneath floors; (4) bedding; (5) sewage; (6) ponds; and (7) soil from paddocks. The corresponding strains were used as indicator test cultures for bacteriophages. The authors employed the following methods to work with bacteriophages: (a) Bacteriophage isolation methods, (b) the Appelman method (i.e., serial dilutions), (c) the Grazia method (i.e., agar layers), (d) phage titration on solid media, and (e) the bacterial phagotyping method.

Results:

The results of the analysis on the bacteria of the Enterobacteriaceae family isolated 11 bacteriophages; one bacteriophage is specific to Pseudomonas aeruginosa, and another one is specific to Brucella abortus. The results also indicate that all bacteriophage strains of the Enterobacteriaceae family demonstrate lysis at a pH of 7.0. In addition, this polyphage lyses all strains of sensitive bacterial cultures. The optimum temperature for the cultivation of bacteriophages is 35°C. While using electron microscopy to study the consortium of bacteriophages, clearly distinguishable virions of bacteriophages were found in the microscope field of view.

Conclusion:

The main parameters for the production of polyphages include the ratio of the bacteriophage and its corresponding bacteriophage-sensitive culture, the pH of the cultivation medium, and the cultivation time of the bacteriophage system as well as the sensitive bacterium. With regard to the aforementioned parameters, the results indicate that the average value for all bacteriophages is 1:2, and the average cultivation medium pH is 7.0 for all bacteriophages. The average cultivation time for all bacteriophages is 18-24 h.