PhD in Veterinary Sciences for Animal Health and Food Safety

Contacts

Supervisor

Marco Gandini

Curriculum vitae

Curriculum Vitae

Phd thesis

Title

Evaluation of the efficiency of the honey-based devices in preventing and treating surgical site infections and in promoting the healing of incisional hernias in rat models.

Scientific background

Surgical Site Infections (SSIs) are among the most common postoperative infections and one of the most reported nosocomial infections in surgical practice.¹ SSIs cause an increase of mortality and morbidity and enhance the risk of surgical revision along with hospitalization costs and prolonged wound management. Infection of laparotomic wounds is one of the most common postoperative complications both in human and in veterinary medicine with an increased risk of wound dehiscence and abdominal hernia after surgery.^2,3 Furthermore, SSIs are increasingly complicated by the presence of antimicrobial resistant bacteria and the antimicrobials used both for prophylaxis and for treatment of incisional infections are often not effective. It would be useful to implement prophylaxis measures that prevent bacterial growth but simultaneously do not increase the risk of antimicrobial resistance.⁴ Medical grade honey may represent a valid alternative to prevent and counteract SSIs. Complex composition of honey, which includes several substances with antimicrobial properties, makes it a particularly effective antimicrobial agent with several mechanisms of action against bacteria. This, together with the difficulty of developing resistance to honey, indicates that it could be an effective alternative against multi-resistant pathogens.^5,6 Furthermore, honey has anti inflammatory properties and promote tissue regeneration and healing, as already shown in previous studies.^7-9

Aims

The first aim of the project is to evaluate the effectiveness of Pectin-Honey Hydrogels (PHHs) in preventing the onset of SSIs in rats. Specifically, a multibacterial infection of laparotomic wound in rats utilizing the caecal content will be created and PHH will be applied on wound before skin closure on treated animals. Comparison between treated and untreated animals will be performed. Differences in term of wound healing, through macroscopic and histopathological evaluation, will be compared. A qualitative comparison of wound bacterial contamination at the end of the experiment will be also performed.
The second aim is to evaluate the effectiveness of PHH-coated polypropylene mesh in promoting the healing of abdominal hernias in contaminated environment. Abdominal wall defect will be performed and left unrepaired in order to create an incisional hernia. After hernia formation, the wound will be experimentally contaminated. Comparison between treated and untreated animals will be performed. The difference in healing process of the abdominal defect (through macroscopic and histopathological evaluation) and the difference in terms of bacterial contamination of the wounds will be compared.

Materials and methods

PHH, PHH-coated mesh ^7,10 and Caecal slurry (CS) ¹¹ will be prepared according to previously
described methods. Sprague-Dawley rats (n=120) will be assigned to 4 groups. In group 1 and 2, a ventral midline incision will be performed, the fascia will be closed, CS will be applied on the wound in both groups and a PHH will be applied before skin closure only in treated animals. In both groups, blood samples will be collected before surgery and at three postoperative times (24 and 72 h and at the time of euthanasia). Levels of IL-1β, IL-6, TNF-α and PGE2 will be measured with a commercial ELISA kit.10 At each experimental time, wound macroscopic observations will be also performed. At 15th postoperative day the rats will be euthanized. A macroscopic evaluation of wounds will be made, and a swab will be performed for bacterial culture. The linea alba will be histologically evaluated. In Group 3 and 4 abdominal hernias will be created and a mesh hernia repair will be performed after inoculation of CS on wounds. A PHH-coated mesh will be used for Group 3 (treated), while a non-coated mesh will be used in Group 4. In both groups, blood samples will be collected before surgery and at three postoperative times (after 24 and 72 h and at the time of euthanasia). Levels of IL-1β, IL-6, TNF-α and PGE2 will be measured with a commercial ELISA kit.10 At each experimental time, wound macroscopic observations will be also performed. At 15th postoperative day the rats will be euthanized. A swab will be performed for bacterial culture and the abdominal wall will be harvested for histological evaluation. All procedures will be approved by the Bioethical Committee of the University of Turin and by the Italian Ministry of Health. The number of cases developing SSI in each group will be compared with chi-square or Fischer’s exact test. Groups 1 and 2 will be compared for wound healing status and presence of signs of infection that will be graded depending on development of dehiscence, presence of discharge, linea alba adhesions with viscera. Quantitative scores of inflammation and tissue healing will be assigned at histological examination and compared with a Student t test or Mann-Whitney test.¹⁰ Groups 3 and 4 will be compared for hernia healing status that will be graded for linea alba closure, presence of discharge, linea alba adhesions with viscera. Quantitative scores of inflammation and tissue healing will be assigned at histological examination and compared with a Student t test or Mann-Whitney test.¹⁰ In all groups qualitative description of bacterial contamination will also be performed. Statistical significance will be set with p <0.05.

Expected results
It is expected that the use of PHHs will counteract the induced infections in rats undergoing laparotomy. Rats of Group 1 should have an optimal healing of the wounds at the time of euthanasia. Signs of infection (dehiscence, presence of discharge, linea alba adhesions with viscera, signs of inflammation) are expected to be reduced in Group 1 than in Group 2. Bacterial contamination also should be lower in treated animals than control group. It is expected that the application of PHH-coated mesh is useful to ensure an optimal healing of abdominal hernias counteracting bacterial growth during tissue regeneration process. It is expected that hernia healing will be complete and there will be less signs of infection in treated than untreated group. If proven effective, the use of PHH would contribute to reduce the use of antimicrobial drugs in the perioperative period, which therefore also leads to a reduction in the risk of antibiotic resistance. Furthermore, this project (along with previous studies on this subject) will serve as a preclinical test for the employment of PHH both in human and veterinary medicine. Applications of PHH in these fields will be mainly directed in counteracting naturally occurring SSI in soft tissue surgery but also in orthopaedic surgery. 

References:

1. Behera HS, Chayani N, Bal M, et al. Identification of population of bacteria from culture
   negative surgical site infection patients using molecular tool. BMC Surg. 2021;21(1):28.
2. Walming S, Angenete E, Block M, Bock D, Gessler B, Haglind E. Retrospective review of risk factors for surgical wound dehiscence and incisional hernia. BMC Surg. 2017;17(1):19.
3. Mair TS, Smith LJ. Survival and complication rates in 300 horses undergoing surgical
   treatment of colic. Part 3: Long-term complications and survival. Equine Vet J. 2005;37(4):310-314.
4. Ghasemian Lemraski E, Jahangirian H, Dashti M, et al. Antimicrobial Double-Layer Wound Dressing Based on Chitosan/Polyvinyl Alcohol/Copper: In vitro and in vivo Assessment. Int J Nanomedicine. 2021; 16:223-235.
5. Combarros-Fuertes P, Fresno JM, Estevinho MM, Sousa-Pimenta M, Tornadijo ME, Estevinho LM. Honey: Another Alternative in the Fight against Antibiotic-Resistant Bacteria?. Antibiotics (Basel). 2020;9(11):774.
6. Tramuta C, Nebbia P, Robino P, et al. Antibacterial activities of Manuka and Honeydew honey-based membranes against bacteria that cause wound infections in animals. Antibakterielle Aktivität von Membranen aus Manuka- und Honigtauhonig gegen Wundkeime bei Tieren. Schweiz Arch Tierheilkd. 2017;159(2):117-121.
7. Giusto G, Vercelli C, Comino F, Caramello V, Tursi M, Gandini M. A new, easy-to-make pectin-honey hydrogel enhances wound healing in rats. BMC Complement Altern Med. 2017;17(1):266.
8. Smaropoulos, E., & Cremers, N. (2019). The pro-healing effects of medical grade honey
   supported by a pediatric case series. Complementary therapies in medicine, 45, 14–18.
   https://doi.org/10.1016/j.ctim.2019.05.014
9. McLoone, P., Tabys, D., & Fyfe, L. (2020). Honey Combination Therapies for Skin and Wound Infections: A Systematic Review of the Literature. Clinical, cosmetic and investigational dermatology, 13, 875–888. https://doi.org/10.2147/CCID.S282143
10. Vercelli C, Re G, Iussich S, et al. In Vivo Evaluation of a Pectin-Honey Hydrogel Coating on Polypropylene Mesh in a Rat Model of Acute Hernia. Gels. 2021;7(3):132. Published 2021 Aug 31. doi:10.3390/gels7030132
11. Gupta V, Tyagi A. A rat model of polymicrobial infection in full-thickness excision wounds. J Tissue Viability. 2021;30(4):537-543.

Research activities

Publications: 

1. Gandini M., Cerullo A., Franci P., Giusto G. Changes in perioperative antimicrobial and anti-inflammatory drugs regimens for colic surgery in horses. A single centre report. Vet. Sci. 2022 [Accepted].
2. Gandini M., Cerullo A., Giusto G. Scoping review: occurrence and definitions of postoperative complications in equine colic surgery. Equine Vet. J. 2022; [in press]. DOI: 10.1111/evj.13881
3. Giusto G., Cerullo A., Gandini M. Transillumination techniques for vessel identification during small colon resection in six horses [published online ahead of print, 2022 Aug 25]. J Equine Vet Sci. 2022;104113. doi:10.1016/j.jevs.2022.104113.
4. Gialletti R., Nannarone S., Gandini M., Cerullo A., Bertoletti A., Scilimati N., Giusto G. Comparison of Mesh and Barbed Suture for Laparoscopic Nephrosplenic Space Ablation in Horses. 2021. Animals 11, no. 4: 1096. https://doi.org/10.3390/ani11041096.
5. Giusto G., Cerullo A., Labate F.,  Gandini M. Incomplete Ileocecal Bypass for Ileal Pathology in Horses: 21 Cases (2012– 2019). 2021. Animals 11, no. 2: 403. https://doi.org/10.3390/ani11020403.
6. Giusto G., Cerullo A., Gandini M. Gastric and Large Colon Impactions Combined With Aggressive Enteral Fluid Therapy May Predispose to Large Colon Volvulus: 4 Cases.  J. Equine Vet. Sci. 2021. Vol. 102. https://doi.org/10.1016/j.jevs.2021.103617.
7. Giusto G., Cerullo A., Gandini M. Surgical colic caused by fibrous bands and adhesions in absence of previous abdominal surgery: 9 cases (2011- 2019). Equine vet edu. 2021.  https://doi.org/10.1111/eve.13487.

Oral presentations:

- 26° International SIVE congress, Bologna 28-29/01/22

1. Verifica dell’associazione tra il sovrappeso e il rischio di infezioni incisionali in seguito a chirurgia di colica nel cavallo

- Game of research, North edition, Turin 16/12/22

1. Valutazione dell’utilizzo di dispositivi a radiofrequenza (Caiman^®) per saldature intestinali nel cavallo: studio ex vivo

Posters: 

- International Equine Colic Research Symposium 2020, Online

1. Surgical colic caused by adhesions in absence of previous abdominal surgery: 9 cases
   (2012-2019)
2. Tick-borne diseases as a cause of postoperative fever after colic surgery in Northern
   Italy
3. Incomplete Ileocecal Bypass for Ileal Pathology in Horses: 21 Cases (2012-2019)

- 26° International SIVE congress, Bologna 28-29/01/22

1. Valutazione del rapporto tra lunghezza della sutura e lunghezza della ferita come fattore
   di rischio per l'infezione del sito chirurgico in seguito a laparotomia nei cavalli
2. Confronto clinico tra sutura continua di lembert e graffe metalliche per l'anastomosi
   termino-terminale digiuno-digiunale nei cavalli

Professional Training: 

1. Elementi base per l'approccio dei ricercatori all'utilizzo degli animali ai fini scientifici. Istituto zooprofilattico sperimentale della Lombardia e dell'Emilia Romagna - Portale formazione. Online Course
2. 5th International Colic Surgery Conference and Laboratory, 29/11/22 - 06/12/22 University of Florida, Professional and Workforce Development. Online Course

Publications

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