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International Journal of Bioprinting 3D printing innovations against infection

Melamine is a unique chimeric cationic peptide with complications, especially in patients undergoing prolonged
significant potential for anti-microbial adhesion and catheterization. Globally, UTIs contribute to 30%–40%
biofilm formation, and disrupts microbial cell membrane of hospital-acquired infections, with approximately 80%
it interacts with, leading to microbial death. Its high of these cases attributed to indwelling urinary catheters,
efficiency and specificity make it a highly sought-after commonly referred to as catheter-associated urinary tract
antimicrobial tool. A study from Cometta et al. infections (CAUTI). 134
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showed that melamine was successfully immobilized Biofilm formation on the surface of indwelling
onto the surface of medical polycaprolactone scaffolds
by covalent and non-covalent methods. This modified urinary catheters is a primary factor contributing to the
scaffold maintained its antimicrobial properties for 3 onset of CAUTIs, a process driven by intricate biological
days, effectively reducing S. aureus colonization and and chemical mechanisms: (i) Upon catheter insertion
inhibiting biofilm formation in vitro. This strategy into the bladder, metabolites, proteins, and other
provides a biomaterial solution to prevent biofilm- inorganic substances present in the urine are prone
associated infections on implant surfaces, avoiding to deposition on the catheter’s surface, initiating the
over-reliance on systemic antibiotic therapy. AMPs are formation of a thin film, i.e., biofilm. This phenomenon
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naturally occurring small molecular proteins in the body creates an optimal environment for the attachment,
with both bactericidal and bacteriostatic properties. They growth, and multiplication of microorganisms,
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exhibit antimicrobial activity against a broad spectrum including bacteria and fungi. The deposits on the
of pathogens, including Gram-positive and Gram- catheter’s surface serve as a nutrient-rich substrate
negative bacteria, fungi, parasites, and enveloped viruses. essential for bacterial proliferation. (ii) While catheter
Moreover, AMPs are typically biocompatible and do surfaces are inherently resistant to adhesion, the
not elicit an excessive immune response or cause tissue biofilm formation process compromises this resistance,
damage. Therefore, they are well-suited for surface coating making it easier for bacteria to adhere to the catheter’s
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or modification of implants. In a study conducted surface and establish a biofilm. This biofilm acts
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by Zhang et al., Mel4, an antimicrobial peptide, was as a protective enclave, enabling bacteria to colonize
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encapsulated on titanium plates for treating infections and exhibit resilience against antibiotic treatment and
following femur fracture fixation. The researchers immune system responses. (iii) Catheter insertion
assessed the impact of in vivo femur fracture fixation on introduces a communication link between the otherwise
Mel4-treated infections by intravenously injecting rabbits relatively sterile intravesical environment of the bladder
with S. aureus or P. aeruginosa suspension. The results and the external surroundings. This facilitates the entry
demonstrated a significant inhibitory effect of Mel4- of bacteria from the urethra and the vicinity of the
coated titanium plates on S. aureus and P. aeruginosa, catheter, such as Escherichia coli, Enterococcus faecalis,
underlining a promising method for controlling and S. epidermidis, into the bladder. Once inside the
postoperative infections in open fractures. bladder, these microorganisms can ascend along both
the internal and external surfaces of the catheter,
4.2. Innovation of 3D-bioprinted catheter for instigating the development of UTIs. 137,138
infection prevention
A catheter is a crucial medical device employed in To address these challenges, standard treatment
urology and clinical care, primarily designed to assist protocols typically involve periodic catheter replacements,
patients in the process of urination. Typically, the catheter typically occurring every 1 to 3 months. This practice aims
is introduced into the patient’s bladder, guiding urine to mitigate biofilm formation and microbial accumulation
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through a tube into a collection container or urine bag. on the catheter surface. If patients develop CAUTIs, oral
This facilitates the monitoring of urine output, alleviates antibiotics may be prescribed for therapeutic intervention.
the discomfort associated with an overfilled bladder, and However, combating biofilms proves to be challenging due
provides a convenient means for urine sampling during to their high resistance to conventional antibiotics. At
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specific medical procedures. Despite the essential role of present, 3D-printed antimicrobial catheters have emerged
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catheters in medical practice, they pose a potential risk for as a promising adjunctive treatment. These catheters
urinary tract infections (UTIs). The insertion of a catheter are crafted using specialized materials that incorporate
involves traversing the bladder wall through the urethra, antimicrobial agents, such as silver ions or antibiotics.
a procedure that may introduce bacteria, consequently The incorporation of these agents facilitates the controlled
heightening the susceptibility to UTIs, which are prevalent release of antimicrobial substances during catheter
hospital-acquired infections, causing symptomatic use, thereby reducing biofilm formation and microbial
discomfort, pain, and, in severe cases, significant health adherence (Figure 5). 141

Volume 10 Issue 4 (2024) 134 doi: 10.36922/ijb.2338