Braided silk sutures coated with photoreduced silver nanoparticles for eradicating Staphylococcus aureus and Streptococcus mutans infections

BACKGROUND

Infections resulting from surgical procedures and wound closures continue to pose significant challenges in healthcare settings. To address this issue, the investigators have developed antibacterial non-resorbable braided silk sutures using in situ deposited silver nanoparticles (AgNPs) and investigated their efficacy in eradicating Staphylococcus aureus and Streptococcus mutans infections.

METHODS

The braided silk sutures were modified through a simple and efficient in situ photoreduction method, resulting in the uniform distribution of AgNPs along the suture surface. The synthesized AgNPs were characterized using scanning electron microscopy (SEM), dynamic light scattering analysis (DLS) and Fourier Transform Infrared Spectroscopy analysis (FTIR) confirming their successful integration onto the silk sutures. The antibacterial activity of the nanoparticle coated sutures were compared and evaluated with non-coated braided silk sutures through in vitro assays against both S. aureus and S. mutans.

RESULTS

The surface and cross-sectional analysis of the treated sutures revealed a uniform and homogeneous distribution of silver particles achieved through the photoreduction of silver solution. This observation confirms the successful coating of silver nanoparticles (AgNPs) on the sutures. The antimicrobial studies conducted, demonstrated significant reductions in bacterial colonies when exposed to the silver nanoparticle-coated sutures. Notably, the width of the inhibition zone surrounding the coated sutures remained consistently wide and stable for duration up to 7 days. This sustained and robust inhibitory effect against gram-positive bacteria, specifically S. aureus and S. mutans, serves as strong evidence of the antibacterial efficacy of the coated sutures.

CONCLUSION

The coating of silk sutures with AgNPs provided a significant and effective antibacterial capacity to the surgical sutures, with this activity being sustained for a period of 7 days. This suggests that AgNPs-in situ photoreduction deposited sutures have the potential to effectively manage S. aureus and S. mutans infections.

Comparison of bacterial colonization on absorbable non-coated suture with Triclosan- or Chlorhexidine-coated sutures: a randomized controlled study

OBJECTIVE

The oral cavity is a colossal reservoir for the bacteria. The healing of tissues is compromised after flap surgery, particularly in the presence of sutures, as they can act as repositories for bacteria, ultimately leading to surgical site infections. Hence, antibacterial-coated sutures have been considered as an alternative to reduce the risk of these infections and further improve the wound healing of the tissues after flap surgery. Since minimal information is available on the effect of antibacterial-coated sutures on periodontal tissues, this study aims to clinically and microbiologically assess the antibacterial efficacy of Triclosan (TCS) and Chlorhexidine-coated sutures (CCS) on periodontal tissues compared to non-coated sutures (NCS).

PATIENTS AND METHODS

A total of 75 subjects with moderate to severe periodontitis were included in the study and randomly allocated to one of the three groups, (TCS, CCS, and NCS groups) equally. Suture removal was performed on postoperative day 8, and parameters such as wound healing and post-operative pain were evaluated. The retrieved suture samples were subjected to microbiological analysis and the bacteria were identified quantitatively and qualitatively.

RESULTS

Intragroup analysis of the wound healing index and post-operative pain for all the groups showed a significant improvement (p<0.01), from day 8 to day 30. Intergroup analysis of the wound healing index revealed significant wound healing (p<0.05) on day 15 and day 30. For post-operative pain, intergroup analyses showed significantly low pain scores (p<0.01) for the TCS group. Microbiologic analysis of aerobic colony counts in both anterior and posterior regions revealed significantly (p<0.01) least colony counts in TCS and highest colony counts in NCS groups, respectively. Although anaerobic colony counts were not statistically significant, relatively fewer colony counts were identified in the TCS group. Whereas, relatively higher anaerobic colony counts were seen in the CCS group in the anterior region and in the NCS group in the posterior region. Qualitative assessment revealed higher amounts of Streptococcus and Staphylococcus species in all the three groups (TCS, CCS, and NCS groups).

CONCLUSIONS

Antibacterial-coated sutures, particularly Triclosan-coated sutures, are effective in reducing bacterial accumulation compared to non-coated sutures. Therefore, these sutures can be effectively utilized in periodontal flap surgery.

INFECTIOUS ENDOPHTHALMITIS AFTER SCLERAL FIXATION OF AN INTRAOCULAR LENS

PURPOSE

To determine the mechanism of infection, clinical features, and risk factors of endophthalmitis after scleral fixation of an intraocular lens.

METHODS

We included 15 patients with infectious endophthalmitis after scleral fixation of an intraocular lens between April 2004 and December 2017, as well as four patients found through a literature search. Thus, a total of 19 patients were analyzed.

RESULTS

Among 19 eyes, infectious endophthalmitis developed at a mean of 23 months (range: 1 day-10 years) after scleral fixation surgery. Nine eyes (47.4%) had early-onset endophthalmitis (≤6 weeks), and 10 eyes (52.6%) had delayed-onset endophthalmitis (>6 weeks). Eleven eyes (57.9%) had presumed microbial influx due to suture exposure. Those with delayed-onset endophthalmitis showed a higher rate of suture-related infection (80.0% vs. 33.3%) and culture of gram-negative bacteria (70.0% vs. 12.5%) than did those with early-onset endophthalmitis.

CONCLUSIONS

Infectious endophthalmitis can develop late after scleral fixation of an intraocular lens, usually related to the exposed sutures, and the visual prognosis is poor. Eyes that have sutured scleral fixation should be monitored regularly, and preventive measures should be performed if an exposed suture is found.

Biomimicking Antibacterial Opto-Electro Sensing Sutures Made of Regenerated Silk Proteins

Surgical sutures play an important role across a wide range of medical treatments and a wide variety exist, differing in strength, size, composition, and performance. Recently, increasing interest has been paid to bioactive and electronic sutures made of synthetic polymers, owing to their ability to reduce inflammation as well as medically and/or electronically facilitate wound healing. However, integrating sensing capabilities into bioactive sutures without adversely affecting their mechanical strength, biocompatibility, and/or bioactivity remains challenging. In this work, a set of biomimicking, antibacterial, and sensing sutures based on the regenerated silk fibroin is designed and fabricated. These sensing sutures, inspired by the "core-shell" multilayered structure of natural spider-silk fibers, are hierarchically structured and heterogeneously functionalized to allow for the integration of multiple, clinically favorable functions into one suture device. These functions included: reducing inflammation and bacterial infection in wound sites, measuring tension of both the tissue and suture, and aiding tissue healing via multi-modal controlled drug and growth factor release. Critically, these functions are coupled with real-time optical and electronic monitoring capabilities. This approach provides greater insight into multifunctional sutures with inherent sensing capabilities and offers enormous potential in both therapeutic and diagnostic applications.

In vitro and in vivo study of novel antimicrobial gellan-polylysine polyion complex fibers as suture materials

GELLAN GUM: and gellan-derived materials have never been used for suture materials due to their lack of strength and toughness. In this study, gellan and ε-polylysine formed a polyion complex in water solution, and the complex was transformed into fibers via wet-spinning. The fibers were bundled, twisted, and elongated, and the resultant twisted and elongated yarn (GPF) had a diameter of 97.53-103.76 μm and tensile strength of 4 N. The swelling ratio of GPF was 165.55%-183.23% in weight in normal saline, and the linear density was 2.84-3.31 g/km. GPF was tested using agar diffusion tests and it was found that the fibers had good antibacterial activity against Escherichia coli and Staphylococcus epidermidis. In weight loss experiments, GPF was found to be undegradable in normal saline and slightly degradable (residual weight ratio was 83.2 ± 1.2%) in simulated body fluid with trypsin within 7 days. Moreover, GPF showed no cytotoxicity toward BV-2 cells in cytotoxity tests with CCK8 and no hemolysis in hemolytic tests with fresh C57 mice blood. Finally, GPF was assessed using mouse dorsal cross-cutting model, and none of the mice that were tested with GPF showed infection or rejection reaction. Therefore, GPF is a promising suture material, and this study provides a new development direction for the application of gellan materials with improved mechanical properties.

Investigation of the in vitro antimicrobial activity of triclosan-coated suture material on bacteria commonly isolated from wounds in dogs

OBJECTIVE

To investigate in vitro effects of triclosan coating of suture materials on the growth of clinically relevant bacteria isolated from wounds in dogs.

SAMPLE

6 types of suture material and 10 isolates each of methicillin-susceptible Staphylococcus pseudintermedius, methicillin-resistant S pseudintermedius, Escherichia coli, and AmpC β-lactamase and extended-spectrum β-lactamase-producing E coli from clinical wound infections.

PROCEDURES

Isolates were cultured on Mueller-Hinton agar with 3 types of triclosan-coated suture, uncoated counterparts of the same suture types, and positive and negative controls. Zones of inhibition (ZOIs) were measured after overnight incubation. Sustained antimicrobial activity assays were performed with susceptible isolates. The ZOI measurements and durations of sustained antimicrobial activity were compared among suture types and isolates by statistical methods. Suture surface characteristics and bacterial adherence were evaluated qualitatively with scanning electron microscopy.

RESULTS

ZOIs were generated only by triclosan-coated materials; triclosan-coated suture had sustained antimicrobial activity (inhibition) for 3 to 29 days against all tested pathogens. The ZOIs around triclosan-coated suture were significantly greater for S pseudintermedius isolates than for E coli isolates. Bacterial adherence to uncoated polyglactin-910 was greatest, followed by triclosan-coated polyglactin-910, and then uncoated monofilament sutures, with least adherence to coated monofilament sutures.

CONCLUSIONS AND CLINICAL RELEVANCE

Surface characteristics of suture materials may be as important or more important than triclosan coating for microbial inhibition; however, triclosan coating appeared to affect bacterial adherence for multifilament sutures. Triclosan-coated, particularly monofilament, sutures inhibited pathogens commonly isolated from wounds of dogs, including multidrug-resistant bacteria. Further studies are required to assess clinical efficacy of triclosan-coated suture materials in vivo.

Forgotten pathogen: tetanus after gastrointestinal surgery

A previously healthy 79-year-old woman underwent an urgent laparotomy and resection of a strangulated loop of small bowel. On the second postoperative day, she developed symptoms suspicious for postoperative tetanus. A transfer to the intensive care unit was necessary for aggressive supportive therapy. The patient required 5 months of intensive physiotherapy and rehabilitation and was successfully discharged home. New cases of tetanus have become rare in developed countries. This potentially lethal disease affects both non-immunised and inadequately immunised patients. The occurrence of tetanus after gastrointestinal surgery is extremely rare. Prevention is key and can be achieved with correct immunoprophylaxis. Older patients are often inadequately immunised. Should tetanus immunoprophylaxis routinely be checked for elderly patients undergoing gastrointestinal surgery? Or can we limit the immunisation to severe cases of ischaemic bowel injury with necrosis and/or soiling of the abdominal cavity?

Antimicrobial characteristics and biocompatibility of the surgical sutures coated with biosynthesized silver nanoparticles

Surgical sutures play important role during the wound healing of the surgical sites which are known to be sensitive to microbial infections. Silver nanoparticles (AgNPs) have been recently used as promising agents against multiple-drug resistant microorganisms. This study was designed to coat the sutures with silver nanoparticles obtained via a green synthesis approach. Microbial-mediated biological synthesis of AgNPs were carried out ecofriendly using Streptomyces sp. AU2 cell-free extract and deposited on silk sutures through an in situ process. Sutures coated with biosyntehsized AgNP (bio-AgNP coated sutures) were characterized using Scanning Electron Microscopy (SEM) and elemantal analysis were carried out using Energy Dispersive X-ray Spectroscopy (EDS). The silver amount released by the bio-AgNP coated sutures was calculated by Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS) throughout a degradation process. Antimicrobial potential of the bio-AgNP coated sutures was determined against common pathogenic microorganisms Candida albicans, Escherichia coli and Staphylococcus aureus. To determine the biocompatibility/cytotoxicty of the bio-AgNP coated sutures, the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium) assay was used through an indirect test method; that the elutions obtained by the extraction of the sutures at 1, 4, 8 and 10. days and were placed in contact with 3T3 fibroblast cell culture. To best of our knowledge, this is the first report about coating of the nonabsorbable silk sutures with silver nanoparticles biosynthesized using a microbial extract.

Bacterial colonisation of suture material after routine neurosurgical procedures: relevance for wound infection

BACKGROUND

Wound healing impairment is a serious problem in surgical disciplines which may be associated with chronic morbidity, increased cost and patient discomfort. Here we aimed to investigate the relevance of bacterial colonisation on suture material using polymerase chain reaction (PCR) to detect and taxonomically classify bacterial DNA in patients with and without wound healing problems after routine neurosurgical procedures.

METHODS

Repeat surgery was performed in 25 patients with wound healing impairment and in 38 patients with well-healed wounds. To determine the presence of bacteria, a 16S rDNA-based PCR detection method was applied. Fragments of 500 bp were amplified using universal primers which target hypervariable regions within the bacterial 16S rRNA gene. Amplicons were separated from each other by single-strand conformation polymorphism (SSCP) analysis, and finally classified using Sanger sequencing.

RESULTS

PCR/SSCP detected DNA of various bacteria species on suture material in 10/38 patients with well-healed wounds and in 12/25 patients with wound healing impairment including Staphylococcus aureus, Staphylococcus epidermidis, Propionibacterium acnes and Escherichia coli. Microbiological cultures showed bacterial growth in almost all patients with wound healing impairment and positive results in PCR/SSCP (10/12), while this was the case in only one patient with a well-healed wound (1/10).

CONCLUSIONS

Colonisation of suture material with bacteria occurs in a relevant portion of patients with and without wound healing impairment after routine neurosurgical procedures. Suture material may provide a nidus for bacteria and subsequent biofilm formation. Most likely, however, such colonisation of sutures is not a general primer for subsequent wound infection.

Multi-Drug Resistant Surgical Site Infection Due to Mycobacterium abscessus Complex

M. abscessus complex is notoriously resistant to most antimicrobial agents. The complex is differentiated into 3 subspecies: M. abscessus subsp. abscessus, M. abscessus subsp. massiliense, and M. abscessus subsp. bolletii. Skin and soft tissue infections due to this organism can be acquired by direct contact with contaminated material through traumatic injury, surgical wound and environmental exposure or by secondary involvement of skin/soft tissue during disseminated disease. We report a case of Mycobacterium abscessus infection recovered from a post-operative mid-line abdominal wound to illustrate the diagnostic and management difficulties encountered in such patients.

Cleaning with a wet sterile gauze significantly reduces contamination of sutures, instruments, and surgical gloves in an ex-vivo pelvic flexure enterotomy model in horses

The objective of this study was to investigate whether cleaning surgical materials used to close pelvic flexure enterotomies with a wet sterile gauze will reduce contamination and whether the use of a full thickness appositional suture pattern (F) or a partial thickness inverting (or Cushing) suture pattern (C) would make a difference in the level of contamination. Large colon specimens were assigned to group F or C and divided into subgroups N and G. In group G, a wet sterile gauze was passed over the suture material, another over the instruments, and another over the gloves. In group N, no treatment was applied. The bacterial concentration was measured by optical density (OD) at 24 h. The OD of subgroup CG was lower than that of subgroup CN (P = 0.019). The OD of subgroup FG was lower than that of subgroup FN (P = 0.02). The OD of subgroups CG, CN, FG, and FN was lower than that of the negative control (P < 0.003, P < 0.001, P < 0.001, and P < 0.00). The use of a sterile wet gauze significantly reduced contamination of suture materials. A partial thickness inverting suture pattern did not produce less contamination than a full thickness appositional suture pattern.

Adherence of methicillin-resistant Staphylococcus pseudintermedius to suture materials commonly used in small animal surgery

OBJECTIVE

To evaluate adherence of methicillin-resistant Staphylococcus pseudintermedius (MRSP) to 5 suture materials commonly used in small animal surgery.

SAMPLE

10 epidemiologically unrelated MRSP isolates (obtained from dogs with clinical infections) that had strong biofilm-forming ability and 5 types of suture.

PROCEDURES

The 5 types of suture evaluated were monofilament polyglecaprone 25, monofilament polydioxanone, triclosan-coated (TC)-monofilament polydioxanone, braided polyglactin 910, and barbed monofilament polydioxanone. Suture segments were incubated in standard suspensions of MRSP for 2 minutes. Segments were then placed in tryptone soy broth and incubated overnight. After incubation, segments were rinsed with PBS solution and sonicated to dislodge adherent bacteria. Resulting suspensions were used to create serial dilutions that were plated, incubated overnight, and counted the following day. Bacterial adherence to 1 segment of each suture type was assessed by use of scanning electron microscopy.

RESULTS

There was significantly less adherence of MSRP to TC-monofilament polydioxanone than to polyglecaprone 25, polyglactin 910, barbed monofilament polydioxanone, and monofilament polydioxanone. There was significantly less adherence of MSRP to polyglecaprone than to polyglactin 910.

CONCLUSIONS AND CLINICAL RELEVANCE

Barbed suture had a bacterial adherence profile comparable to that for monofilament suture. Adherence of MRSP was greatest for braided polyglactin 910. Use of TC-monofilament polydioxanone can be considered for patients that are at high risk of developing surgical site infections and for which a surgeon chooses a multifilament suture.

16S rRNA analysis provides evidence of biofilms on all components of three infected periprosthetic knees including permanent braided suture

Bacterial biofilms are the main etiological agent of periprosthetic joint infections (PJI); however, it is unclear if biofilms colonize one or multiple components. Because biofilms can colonize a variety of surfaces, we hypothesized that biofilms would be present on all components. 16S ribosomal RNA (rRNA) gene sequencing analysis was used to identify bacteria recovered from individual components and non-absorbable suture material recovered from three PJI total knee revision cases. Bray-Curtis non-metric multidimensional scaling analysis revealed no significant differences in similarity when factoring component, material type, or suture versus non-suture material, but did reveal significant differences in organism profile between patients (P < 0.001) and negative controls (P < 0.001). Confocal microscopy and a novel agar encasement culturing method also confirmed biofilm growth on a subset of components. While 16S sequencing suggested that the microbiology was more complex than revealed by culture contaminating, bacterial DNA generates a risk of false positives. This report highlights that biofilm bacteria may colonize all infected prosthetic components including braided suture material, and provides further evidence that clinical culture can fail to sufficiently identify the full pathogen profile in PJI cases.

Oral bacteria adherence to suture threads: an in vitro study

PURPOSE

This study investigated the adherence of oral microorganisms to different types of suture threads.

METHODS

Pieces of thread were distributed on 24-well plates, according to the following groups: (G1) nylon, (G2) silk, (G3) polyglactin 910, (G4) polyglactin 910 with triclosan. Blank control (G5) consisted of one thread from each group. Adherence to thread tests was performed to observe adhesion of total microorganisms from saliva or two isolates of Prevotella intermedia (ATCC49046) and Fusobacterium nucleatum (ATCC51190). Brain-heart infusion (BHI) medium with or without bacterial inoculum (1.8 × 10(7) CFU/mL) was added to each well of microplates. The microplates were incubated in an anaerobic chamber at 37 °C, for 5 days for biofilm formation.

RESULTS

There was no difference between the groups as regard to adhesion of F. nucleatum (p > 0.05). For P. intermedia, the threads in G1 and G4 showed a lower level of adhesion (p < 0.05), with no difference between them. Against total microorganisms, G1 presented a lower level of adherence (p < 0.05), followed by G4; and no difference was observed between G2 and G3.

CONCLUSIONS

Total microorganisms and P. intermedia have different affinities to the tested suture threads, whereas F. nucleatum presented a similar adherence level. Among the threads, nylon (G1), followed by polyglactin 910 with triclosan (G4) presented the lowest microbial adherence level.

Comparison of antibacterial-coated and non-coated suture material in intraoral surgery by isolation of adherent bacteria

OBJECTIVES

In general surgery the incidence of postoperative wound infections is reported to be lower using triclosan-coated sutures. In intraoral surgery, sutures are faced with different bacterial species and the question arises whether the antibacterial-coated suture material has the same positive effects.

MATERIALS AND METHODS

Triclosan-coated and uncoated suture materials were applied in 17 patients undergoing wisdom tooth extraction. Postoperatively, sutures were removed and adherent bacteria were isolated, colony-forming units (cfu) were counted, and species identified.

RESULTS

Oral bacteria were found in high numbers (cfu>10(7)) on both Vicryl and the triclosan-coated Vicryl Plus. The total number of bacteria isolated from Vicryl Plus was 37% higher than for Vicryl, mainly due to increased numbers of anaerobes. The number of bacterial strains identified was higher for Vicryl ( n=203) than for Vicryl Plus (n=198), but the number of pathogens was higher on Vicryl Plus (n=100) than on Vicryl (n=97). Fewer Gram-positive strains were found on Vicryl Plus (n=95) than on Vicryl (n=107) and, conversely, more Gram-negative strains on Vicryl Plus (103vs.96).

CONCLUSIONS

In terms of the total number of oral bacteria, and especially oral pathogens, that adhered to suture material, no reduction was demonstrated for Vicryl Plus. The use of triclosan-coated suture material offers no advantage in intraoral surgery.

New bactericidal surgical suture coating

This paper demonstrates the effectiveness of a new antimicrobial suture coating. An amphiphilic polymer, poly[(aminoethyl methacrylate)-co-(butyl methacrylate)] (PAMBM), inspired by antimicrobial peptides, was bactericidal against S. aureus in time-kill experiments. PAMBM was then evaluated in a variety of polymer blends using the Japanese Industrial Standard (JIS) method and showed excellent antimicrobial activity at a low concentration (0.5 wt %). Using a similar antimicrobial coating formula to commercial Vicryl Plus sutures, disk samples of the coating material containing PAMBM effectively killed bacteria (98% reduction at 0.75 wt %). Triclosan, the active ingredient in Vicryl Plus coatings, did not kill the bacteria. Further Kirby-Bauer assays of these disk samples showed an increasing zone of inhibition with increasing concentration of PAMBM. Finally, the PAMBM-containing coating was applied to sutures, and the morphology of the coating surface was characterized by SEM, along with Vicryl and uncoated sutures. The PAMBM-containing sutures killed bacteria more effectively (3 log(10) reduction at 2.4 wt %) than Vicryl Plus sutures (0.5 log(10) reduction).

Sutures coated with antiseptic pomade to prevent bacterial colonization: a randomized clinical trial

OBJECTIVE

The aim of this study was to assess if an antiseptic pomade could reduce the bacterial colonization on multifilament sutures.

STUDY DESIGN

A randomized clinical trial was conducted with 40 volunteer patients of both sexes aged 18-70, randomly separated into experimental (n = 20) and control (n = 20) groups. The experimental group received pomade-coated sutures (iodoform + calendula) and the control group uncoated sutures. Two millimeters of the suture was harvested from each patient from the 1st to the 15th postoperative day. The bacteria that had adhered to them were cultured. The number of colony-forming units per milliliter (CFU/mL) was determined and the groups were compared using the Mann-Whitney statistical test (P < .05).

RESULTS

The experimental group showed a significant reduction in bacterial growth compared with the control group (P = .002).

CONCLUSIONS

In this experimental model, the antiseptic pomade was effective in reducing bacterial colonization on silk braided sutures.

Interplay of antibiotics and bacterial inoculum on suture-associated biofilms

BACKGROUND

Biofilms are often antibiotic resistant, and it is unclear if prophylactic antibiotics can effectively prevent biofilm formation. Experiments were designed to test the ability of high (bactericidal) concentrations of ampicillin (AMP), vancomycin (VAN), and oxacillin (OXA) to prevent formation of suture-associated biofilms initiated with low (10(4)) and high (10(7)) numbers of Staphylococcus aureus.

MATERIALS AND METHODS

S. aureus biofilms were cultivated overnight on silk suture incubated in biofilm growth medium supplemented with bactericidal concentrations of AMP, VAN, or OXA. Standard microbiological methods were used to quantify total numbers of viable suture-associated S. aureus. Crystal violet staining followed by spectroscopy was used to quantify biofilm biomass, which includes bacterial cells plus matrix components. To observe the effects of antibiotics on the microscopic appearance of biofilm formation, biofilms were cultivated on glass slides, then stained with fluorescent dyes, and observed by confocal microscopy.

RESULTS

In the presence of a relatively low inoculum (10(4)) of S. aureus cells, bactericidal concentrations of AMP, VAN, or OXA were effective in preventing development of suture-associated biofilms. However, similar concentrations of these antibiotics were typically ineffective in preventing biofilm development on sutures inoculated with 10(7)S. aureus, a concentration relevant to contaminated skin. Confocal microscopy confirmed that bactericidal concentrations of AMP, VAN, or OXA inhibited, but did not prevent, development of S. aureus biofilms.

CONCLUSION

Bactericidal concentrations of AMP, VAN, or OXA inhibited formation of suture-associated biofilms initiated with low numbers (10(4)), but not high numbers (10(7)), of S. aureus cells.

Incidence, occurrence rate, and characteristics of suture-related corneal infections after penetrating keratoplasty

PURPOSE

To report the incidence, occurrence rate, and characteristics of suture-related infections after penetrating keratoplasty (PK).

METHODS

Patients who underwent PK at our institution between January 1, 2002, and July 1, 2006, were cross-referenced with patients diagnosed with corneal infections between January 1, 2002, and July 1, 2007. All patient charts were reviewed retrospectively for occurrence of suture-related infections, duration of follow-up, and clinical characteristics.

RESULTS

Of the 487 PKs performed in 412 patients, 22 eyes of 22 patients developed postoperative corneal infections. Of these, 5 eyes were identified as having suture-related graft infections, yielding an occurrence rate of 1.0%. The average follow-up was 3.46 years per PK, yielding an incidence of 2.96 infections per 1000 PK-years. The mean interval from surgery to infection was 8 months (range: 3-23 months). All culprit sutures were in the interpalpebral zone. No patients were using topical antibiotics at the time of infection, and all patients were using topical corticosteroid drops. Cultured organisms included Staphylococcus aureus (3 cases), coagulase-negative Staphylcoccus (1 case), and S. viridans (1 case). In 2 patients with isolated corneal involvement, topical moxifloxacin was initiated, and the patients responded favorably. In 3 patients with corneal infection and an associated hypopyon or endophthalmitis, vitreous biopsy, intravitreal injections of antibiotics, and fortified topical antibiotics were used. One patient required a repeat PK as a result of the infection. Two eyes eventually became phthisical.

CONCLUSIONS

The rate of suture-related infections after PK may be lower than previously reported. In our patients, suture-related infections all occurred within the first 2 years after surgery, and some of them resulted in significant morbidity, underscoring the importance of patient identification of symptoms and early clinical recognition.

Bacterial adherence to suture materials

BACKGROUND

Wound infections may be problematic for physicians. Whether a practitioner is managing complex penetrating trauma or a skin biopsy, there may be a need for suture closure. Suture material is an operator dependent variable and while little objective data exist to guide the choice of suture, it may play a role in wound infection. This study evaluates bacterial adherence to commonly used suture materials with a bioluminescent in vitro model.

METHODS

In all, 11 strands of size 2-0 poliglecaprone suture (Monocryl; Ethicon, Inc, Somerville, New Jersey), polypropylene suture (Prolene; Ethicon, Inc), silk suture (Ethicon, Inc), polyglycolic acid suture (Vicryl; Ethicon, Inc), and antimicrobial polyglycolic acid suture treated with triclosan (VicrylPlus; Ethicon, Inc) were immersed in a broth of Staphylococcus aureus engineered to emit photons. After biofilm formation, the suture strands were irrigated and imaged with a photon-capturing camera system yielding a total photon count that correlates with residual bacteria.

RESULTS

The Vicryl suture had the highest counts and was statistically significant in bacterial adherence versus all other sutures. No other suture material was significantly different from any other.

CONCLUSIONS

This study gives data to guide the selection of suture materials. Absorbable braided suture should not be used in closure of contaminated wounds or wounds at risk for developing infection. The antibiotic impregnated absorbable braided suture was similar to the other suture types; however, it is at risk for reverting to the properties of its untreated counterpart over time. The bacterial adherence of suture materials should be taken into account by all practitioners when closing wounds or debriding infected wounds.

Chronic surgical site infection due to suture-associated polymicrobial biofilm

BACKGROUND

Surgical site infection (SSI) is a common surgical complication; culture-negative SSI presents a particular problem in management.

METHODS

Examination of explanted foreign bodies (sutures) using confocal laser scanning microscopy (CLSM) and fluorescent in situ hybridization (FISH) after surgical exploration of a chronic culture-negative SSI.

RESULTS

Confocal microscopy (CM) demonstrated bacilli and cocci attached to the surface of the explanted sutures in a mixed biofilm. Fluorescent in situ hybridization confirmed that Staphylococci were components of the mixed biofilm. Removal of the foreign bodies (sutures) resolved the chronic infection.

CONCLUSION

Chronic SSI can arise from underlying bacterial biofilms, which can invest implanted foreign bodies and associated soft tissue surfaces.

Tensile strength of absorbable suture materials: in vitro analysis of the effects of pH and bacteria

OBJECTIVE

To evaluate the tensile strength and suture degradation of 5 commonly used absorbable suture materials in different pH and bacteria inoculated media.

DESIGN

In vitro study of the tensile strength as well as the effect of pH and bacteria on suture degradation for 5 common absorbable suture materials.

SETTING

Surgical and Orthopaedics Research Laboratories in Prince of Wales Hospital, New South Wales (Tertiary Hospital/University of New South Wales, Australia).

PARTICIPANTS

Chromic catgut, Vicryl, Caprosyn, Bio-Syn, and Maxon were immersed in sterile urine (control), Escherichia coli (E coli) medium, Proteus mirabilis medium (basic medium with pH of 7.8), and acidic medium with pH 5.6. The tensile strength and suture stability were analyzed after immersion in these media after 1, 7, 14, and 28 days. Three runs of test were performed using the universal tensile strength analyzer Mini Bionix (MTS Systems, Eden Prairie, Minnesota), and statistical tests were performed on these results.

RESULTS

A decrease in suture tensile strength was noted in all 5 sutures with the Maxon suture showing the least deterioration followed by the Vicryl suture. A 1-way analysis of variance test revealed a statistically significant decrease in suture tensile strength over the days of testing, and a post hoc Tukey test confirmed a significant decrease up to day 7 (p < 0.01). The presence of E coli and higher urine pH lead to greater suture degradation, but these were not statistically significant. Linear regression model univariate analysis showed that time contributed to the most significant decrease in tensile strength followed by the types of suture materials tested. The types of media tested were not a significant predictor of tensile strength by itself.

CONCLUSIONS

The Maxon suture showed greater suture tensile strength when compared with other sutures. The presence of pH and bacteria caused variable rates of suture degradation, but the result was not significant.

Suture-related keratitis caused by Corynebacterium macginleyi

We report two cases of suture-related keratitis following penetrating keratoplasty. In both cases, Corynebacterium macginleyi was isolated from corneal specimens. Scanning electron microscopy revealed that corynebacteria could aggregate and form a biofilm. The MICs of sulbenicillin and fluoroquinolones were high for both isolates. Our findings show that C. macginleyi can cause keratitis with biofilm formation.

Study of the efficacy of coated Vicryl plus antibacterial suture in an animal model of orthopedic surgery

PURPOSE

To evaluate the efficacy in vitro and in vivo of a new antibacterial suture, polyglactin 910 suture with triclosan, compared with a traditional braided suture, polyglactin (Vicryl), in a validated animal model of orthopedic infection. Our primary goal was to compare the microbiologic effectiveness of the two sutures. The secondary goal was to evaluate histopathologic signs of an inflammatory response.

METHODS

We used 20 Sprague-Dawley rats. Samples of Staphylococcus epidermidis were diluted to a 0.5 McFarland concentration (100,000 colony-forming units/mL). A surgical steel suture was placed in the spinous process of the rats, and the deep zone of the incision was contaminated bilaterally. Wounds were closed with one of the sutures. After 16 days, the animals were sacrificed, and the surgical wounds were reopened, with cultures being performed of both the zone adjacent to the implant and the deep region of the wound. We also studied the histopathologic features of the tissue adjacent to the implant.

RESULTS

No clinical signs of infection were observed. The culture of the zone adjacent to the implant was positive in nine animals in the polyglactin group vs. three in the polyglactin 910 with triclosan group (p = 0.005). Culture of the deep zone of the wound was positive in ten animals in the polyglactin group vs. six in the polyglactin 910 with triclosan group (p = 0.03). We found predominant polymorphonuclear neutrophil populations in four samples in the polyglactin group vs. two in the polyglactin 910 with triclosan group.

CONCLUSIONS

Under simulated conditions of severe intraoperative contamination, the antibacterial suture reduced the number of positive cultures after surgery by 66.6%. Judging from the available clinical information, its use might contribute to reducing the number of infected implants by 25.8%. Human studies are needed to determine the clinical implications of these results.

Microbial Adherence on Various Intraoral Suture Materials in Patients Undergoing Dental Surgery

PURPOSE

Sutures used in oral surgery should avoid or limit bacterial adhesion and proliferation to those parts exposed to oral fluids. Hence, microbial colonization on various intraoral suture materials from patients undergoing dental surgery was compared.

PATIENTS AND METHODS

During dentoalveolar surgery, various suture materials were used in 60 patients, who were randomly divided into 5 groups of 12. In each group, silk was placed intraorally in association with a different type of suture (ie, Supramid, Synthofil, Ethibond Excel, Ti-cron, Monocryl) at the same site to compare microbial colonization intraindividually. Eight days postoperatively, the sutures were removed, and adhered micro-organisms were isolated, counted, and identified through enzymatic activities and fermentation of sugars.

RESULTS

In all 60 patients, silk sutures exhibited the smallest affinity toward the adhesion of bacteria compared with considerable proliferation with nonresorbable multifilament sutures (Supramid, Synthofil, Ethibond Excel, Ti-cron). On the contrary, the microbial load was significantly lower when absorbable monofilament Monocryl was used. A greater quantity of bacteria was found on nonresorbable sutures than on absorbable ones, and nearly 2 times more facultative anaerobic bacteria were isolated in total.

CONCLUSIONS

Our results show that bacteria adhere with different affinity to various types of suture materials. Absorbable silk and Monocryl exhibited the smallest number of adherent bacteria. Colonization by pathogens on sutures leads to the recommendation that sutures should be removed as early as possible after surgery is performed, to eliminate or to limit the reservoir for oral pathogens. This recommendation is dependent on whether the suture is absorbable.

In-vitro evaluation of the adhesion to polypropylene sutures of non-pigmented, rapidly growing mycobacteria

The ability of non-pigmented, rapidly growing mycobacteria (NPRGM) to attach to polypropylene sutures was evaluated using an in-vitro assay. Thirty clinical isolates and five culture collection strains of NPRGM, together with Staphylococcus epidermidis ATCC 35983, were tested. Mycobacterium fortuitum and Mycobacterium chelonae showed the highest attachment ability, which differed significantly from the results obtained with Mycobacterium peregrinum. According to these results, NPRGM are able to attach to polypropylene sutures, and the species implicated most frequently in human infection showed increased levels of attachment in comparison with the other mycobacteria studied.

In Vitro Antibacterial Efficacy of MONOCRYL Plus Antibacterial Suture (Poliglecaprone 25 with Triclosan)

BACKGROUND

This study evaluated the in vitro efficacy of poliglecaprone 25 suture with triclosan against gram-positive and gram-negative bacteria.

METHODS

Poliglecaprone 25 sutures with and without triclosan were tested for in vitro efficacy against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis, methicillin-resistant Staphylococcus epidermidis (MRSE), Klebsiella pneumoniae, and Escherichia coli by a zone of inhibition assay. The suture also was tested against Escherichia coli in a colonization assay in a dynamic model simulating in vivo conditions. An in vitro triclosan diffusion assay and a sustained efficacy assay were performed by concurrent high-performance liquid chromatography and zone of inhibition assay. To assess stability, antibacterial efficacy testing was performed on samples held more than five months at elevated temperature.

RESULTS

Poliglecaprone 25 suture with triclosan demonstrated significant in vitro efficacy against a range of bacteria. The suture sustained in vitro efficacy for 11 days, corresponding to the in vitro triclosan diffusion profile.

CONCLUSION

Triclosan reduced in vitro colonization of poliglecaprone 25 suture by several strains of bacteria compared with untreated control sutures.

In Vivo Antibacterial Efficacy of MONOCRYL Plus Antibacterial Suture (Poliglecaprone 25 with Triclosan)

BACKGROUND

This study evaluated the ability of poliglecaprone 25 suture with triclosan to inhibit bacterial colonization by Escherichia coli and Staphylococcus aureus in mouse and guinea pig models.

METHODS

Test and control sutures (3-4 cm) were implanted subcutaneously in the dorsal-lateral regions (control on the left side, test on the right side, approximately 3-5 cm apart) in 10 female Hartley guinea pigs (300-400 g) and 10 Swiss Webster mice (20-35 g) via a 20-gauge catheter. The test material was poliglecaprone 25 suture with triclosan (2-0, undyed), and the control material was poliglecaprone 25 suture (2-0, undyed). In the guinea pig model, each implantation site was challenged directly with 4x10(5) colony-forming units (cfu) of S. aureus, whereas in the mouse model, each implantation site was challenged directly with 1.3x10(7) cfu of E. coli through an indwelling catheter. At 48 h post-implantation, the control and test sutures were explanted, and bacterial enumeration was performed.

RESULTS

There was a significant difference (p < 0.05) in the number of bacteria recovered in the study groups 48 h post-implantation. Poliglecaprone 25 suture with triclosan produced a 3.4-log reduction in S. aureus and a 2-log reduction in E. coli compared with standard poliglecaprone 25 suture without triclosan under the same challenge conditions. The difference between the study groups in the number of bacteria recovered was significant (p < 0.05).

CONCLUSION

Poliglecaprone 25 suture with triclosan inhibited bacterial colonization of the suture compared with untreated suture after direct in vivo challenge with S. aureus and E. coli in animal models.

Study of the efficacy of Coated VICRYL Plus® Antibacterial suture (coated Polyglactin 910 suture with Triclosan) in two animal models of general surgery

OBJECTIVES

To evaluate the efficacy in vitro and in vivo of a new antibacterial suture (PGAB) compared with a traditional braided suture (PG). Our primary goals were to study microbiological effectiveness and impact on wound healing of PGAB vs PG. Secondary goal was to analyze influence on inflammatory response.

METHODS

In vitro study: clinical samples of Staphylococcus epidermidis, Staphylococcus aureus, S. hominis, Staphylococcus haemolyticus, Staphylococcus auricularis, Enterococcus faecalis, Corynebacterium spp. and Escherichia coli were studied. We also implanted a flat mesh in 10 minipigs, four incisions each (two PG and two PGAB) two contaminated with S. epidermidis and two not contaminated. Finally, we performed four colic anastomosis in each of 10 minipigs, two contaminated with E. coli and two not contaminated (two PG and two PGAB). We studied the inflammatory and wound healing processes in both models.

RESULTS

We observed a bactericidal efficacy of PGAB against grampositive, and bacteriostatic effect against E. coli. Mesh study: recovered CFU were lower in the group PGAB vs PG. In the group PGAB, inflammatory mediators' concentrations were lower. In the group PGAB, concentrations of wound healing mediators were normal. Colic anastomosis: recovered CFU were lower in the group PGAB vs the group PG. In the group PGAB we observed a reduction of inflammatory mediators. In the group PGAB we observed normalized concentrations of wound healing mediators.

CONCLUSIONS

This study demonstrates microbiological efficacy of PGAB, that normalizes wound healing process, and an anti-inflammatory effect.

Capillary activity of surgical sutures and suture-dependent bacterial transport: a qualitative study

OBJECTIVE

To evaluate the multitude of new synthetic absorbable sutures (both monofilament and multifilament) in comparison with older materials with regard to capillarity and bacterial transport.

METHODS

Sutures of United States Pharmacopoeia (USP) 4-0 thickness were arranged in a three-chamber system under sterile conditions. Either a colorant (liquid transport evaluation) or bacteria (bacterial transport evaluation) were added to the contamination chamber, and movement of colorant or bacteria was evaluated for as long as 30 days.

RESULTS

None of the monofilament sutures transported colorant or bacteria. Colorant transport was found on the pseudomonofilament and multifilament sutures between the first and the fifth day. Escherichia coli were transported on the majority of the multifilament sutures, although no transport was found on silk or polyester sutures. Bacterial transport was most often evident in tests using the motile Proteus mirabilis.

CONCLUSIONS

All multifilament and pseudomonofilament suture designs allowed transport of colorants and bacteria to some degree. The movement of fluids and bacteria did not depend on the absorptive capacity of the sutures, coating, or the presence of an open suture end.

Actinomyces associated with persistent vaginal granulation tissue

BACKGROUND: We report a case of symptomatic actinomycosis associated with vaginal suture erosion and granulation tissue refractory to conservative management, in an outpatient setting. CASE: Three months after total vaginal hysterectomy and uterosacral ligament vaginal vault suspension, a woman complained of painless, intermittent vaginal discharge and spotting. Despite cauterization of granulation tissue, vaginal spotting persisted for another month. On re-examination, braided polyester suture that was found underlying the granulation tissue was removed. Recurrent symptoms, together with a biopsy revealing actinomycetes, prompted a trial of oral penicillin VK. With persistent symptoms and discomfort during attempts in the outpatient clinic, the woman eventually required suture removal in the operating room. Her symptoms subsequently resolved without recurrence, and no further antibiotic treatment was required. CONCLUSIONS: Actinomyces may be associated with persistent granulation tissue and vault suspension suture material. In rare circumstances, when tissue debridement and suture removal in the clinic is unsatisfactory, surgical intervention in the operating room may be necessary. Ten days of antibiotic therapy alone did not eradicate the granulation tissue, and symptoms resolved only after complete removal of the underlying permanent suture.

Tissue reactions to sutures in the presence and absence of anti-infective therapy

BACKGROUND

In the oral cavity, sutures are placed within tissues of high vascularity in a moist environment with infectious potential. The objective of this study was to evaluate tissue reactions at silk and expanded polytetrafluoroethylene (ePTFE) sutures in the presence and absence of anti-infective therapy (AT).

METHODS

Thirty-six sutures were placed within the mandibular keratinized gingiva in six Beagle dogs. Each animal received one braided silk (4-0) and one ePTFE (CV-5) suture in contra-lateral jaw quadrants at 14, 7, and 3 days prior to biopsy. Three animals received daily AT including topical 2% chlorhexidine solution and a systemic broad-spectrum antibiotic. Biopsy specimens allowed histometric analysis of tissue reactions along the central part of the suture loop including the area of perisutural epithelium, ratio inflammatory cells (ICs)/epithelial cells and IC/fibroblasts, and presence/absence of bacterial plaque in the suture track.

RESULTS

A perisutural epithelial sheath was forming within 3 days. The cross-sectional area of the epithelium increased with time for both suture materials (p=0.003) but was particularly pronounced for the silk sutures in the absence of AT. Clusters of IC were present in the perisutural connective tissue and epithelium. Over time, a more prominent increase in IC/fibroblasts was evident for the silk sutures in the absence of AT. The pooled material revealed a significantly higher IC/fibroblast ratio for silk compared with ePTFE sutures (p=0.017). Bacterial plaque influx was detected in 6/9 silk and 0/9 ePTFE suture channels in the presence, and 6/6 and 3/6 suture channels, respectively, in the absence of AT.

CONCLUSIONS

AT may reduce biofilm formation and inflammation along the suture track. Braided silk, however, elicits more severe tissue reactions than ePTFE regardless of infection control.

A scanning electron microscope study of plaque accumulation on silk and PVDF suture materials in oral mucosa

AIM

To examine plaque accumulation on silk and polyvinylidene fluoride (PVDF) sutures at different time intervals.

METHODOLOGY

Twenty-one male albino rabbits received sutures under general and local anaesthesia. After 3, 5 and 7 days sutures were removed and processed for scanning electron microscope (SEM) observation. The Friedman and the Wilcoxon tests were used to compare contamination on PVDF and silk suture materials at different time intervals.

RESULTS

At all time intervals, the whole surface of silk sutures was covered with a thick layer of bacterial plaque and debris. Microorganisms and blood cells on the surface and between the filaments of the silk suture material were observed. Light debris appeared around the knot area of PVDF sutures after 3 days. At 5 and 7 days, contamination could be seen in scattered areas along the suture material. The average contaminated area was smaller on PVDF suture materials, which were removed at 5 than at 7 days after insertion. At 3 days, PVDF sutures showed significantly less contamination than at 5 and 7 days (P = 0.002). There were statistically significant differences between silk and PVDF sutures at 3, 5 and 7 days.

CONCLUSION

SEM observation showed that PVDF sutures were contaminated less than silk sutures at 3, 5 and 7 days.

Evaluation of biofilm formation on nylon sutures removed from clinically noninfected eyes after cataract surgery

PURPOSE

To determine the presence of bacterial biofilm on nylon sutures removed from clinically noninfected eyes after cataract surgery.

SETTING

The Eye Institute, Tan Tock Seng Hospital, Singapore, Singapore.

METHODS

Sutures were removed from 10 eyes after cataract surgery at different time periods. Immediately after removal, the sutures were fixed and dehydrated. All sutures were viewed by scanning electron microscopy, and 6 were also viewed by transmission electron microscopy (TEM).

RESULTS

There was no evidence of bacterial biofilm formation on the nylon sutures. Significant cellular debris was seen, mainly at the knots. Clusters of coccoid-shaped structures were visible; however, examination by TEM showed they were not bacteria.

CONCLUSION

There was no evidence of biofilm formation on sutures removed after cataract surgery from clinically noninfected eyes.

Experimental Efficacy Study of Coated VICRYL plus Antibacterial Suture in Guinea Pigs Challenged with Staphylococcus aureus

BACKGROUND

This study evaluated the ability of coated polyglactin 910 suture with triclosan (Coated VICRYL Plus Antibacterial) suture to inhibit the colonization of bacteria on the suture after direct in vivo inoculation challenge with Staphylococcus aureus utilizing a guinea pig model.

METHODS

One control suture (4-5 cm) and one test suture (4-5 cm) were implanted subcutaneously in the dorsal-lateral regions (control on the left side, test on the right side, approximately 5 cm apart) in 16 female Hartley guinea pigs (300-400 g) via a 20-gauge catheter. Each implantation site was challenged directly with 2.1 x 10(4) colony forming units (cfu) of Staphylococcus aureus through the indwelling catheter. The test material was coated polyglactin 910 suture with triclosan (2-0, dyed), and the control material was coated polyglactin 910 suture (2-0, undyed). At 48 h, suture articles were explanted and a bacterial enumeration assay was performed.

RESULTS

There was a significant difference (p < 0.05) in the number of bacteria recovered between the study groups at 48 h post-implantation. The mean recovery for test sutures was 559 cfu, and the mean recovery for control sutures was 16,831 cfu. Coated polyglactin 910 suture with triclosan provided a 30.5-fold (96.7%) reduction in the number of recovered bacteria compared to standard coated polyglactin 910 suture.

CONCLUSIONS

This study demonstrates that coated polyglactin 910 suture with triclosan inhibits bacterial colonization of suture after direct in vivo challenge with S. aureus in a guinea pig model.

Effect of the Wicking Behavior of Multifilament Sutures

The purpose of this study was to compare the wicking propensity of multifilament sutures. Dexon II, Vicryl, and black silk suture (BSS) were dipped in saline or soaked for 48 h, then suspended on a microscope slide. Fluorescein isothiocyanate-dextran (FITC-D) was placed at the suture mid points, and its movement was observed using fluorescence microscopy. The experiment was repeated, replacing the FITC-D with mixture of S. salivarius and saline, incubating the suture specimens in culture medium, and evaluating microbial growth. Dipped sutures showed FITC-D movement in the Dexon II group only. All 48-h soaked sutures demonstrated FITC-D movement with significant (p < 0.005) differences in mean times: BSS 179 +/- 42 s; Vicryl 120 +/- 26 s; and Dexon II 32 +/- 2 s. Dexon II suture demonstrated wicking of S. salivarius, whereas Vicryl and BSS did not (p < 0.05). These results suggest that BSS and Vicryl sutures do not wick as readily as Dexon II does.

Species-dependent premature degradation of absorbable suture materials caused by infection – Impact on the choice of thread in vascular surgery

Background: In case of infection after vascular reconstruction, preference is often given to absorbable suture material with the aim of preventing persistence of infection. We have investigated the functional deficit of absorbable sutures on incubation with various different bacteria. Material and methods: Four suture materials – Dexon bicolor®, Vicryl®, Maxon® and PDS II® – were placed in contact with reference bacterial cultures (Staphylococcus aureus, Pseudomonas aeroginosa, E. coli, coagulase-negative staphylococci and Proteus mirabilis). The bacteria were incubated for 7 days at 37°C, together with the suture material. A logarithmic phase (Group A) and a static phase (Group B) were simulated. The linear tensile strength (LTS) of the suture material was measured (Instron Tensiometer). Results: In the case of Staphylococcus aureus, a significant decrease in LTS was established for Dexon bicolor® (group A: 31%, group B: 22%), and Vicryl® (53% and 43%), but not for the monofilament threads. With regard to the other bacteria, a considerably more dramatic effect was observed: in both groups the braided sutures had completely disintegrated after 7 days. The monofilament sutures also revealed a significant loss of function (Maxon®: 88%, PDS II® 66%). Conclusions: The absorbable sutures revealed a premature, species-dependent loss of function due to the presence of the bacteria. On the basis of our results, the use of absorbable threads for vessel sutures in case of infection cannot be recommended, with the exception of monofilament material in a monocultural Staphylococcus aureus infection.

Quantification of incidental needle and suture contamination during strabismus surgery

PURPOSE

To quantify the level of bacterial contamination of needles and sutures immediately after use in strabismus surgery.

METHODS

Strabismus surgery was performed on 56 eyes from 31 pediatric strabismus surgical cases. Preoperative site preparation included instillation of 5% povidone-iodine in the conjunctival fornices in all cases. A total of 124 needles and 127 sutures were cultured immediately after final scleral passage.

RESULTS

Seventeen of the 31 cases (54.8%) produced at least one positive specimen. Nineteen per cent of the needles and 25.2% of the sutures were culture positive. The bulk of positive specimens (96.7% of needles, 91.3% of sutures) produced 3 or less colony forming units, corresponding to 7 or less total viable organisms per needle or sutures in accordance with the dilution scheme. Coagulase-negative staphylococci overwhelmingly predominated.

CONCLUSIONS

Needles and sutures used in strabismus surgery can become contaminated during surgery despite preoperative povidone-iodine preparation. The number of viable bacterial contaminants is usually below the level known to consistently produce experimental endophthalmitis. However, a few needles and sutures carried a high contaminant load, suggesting the possibility that contaminated needles and sutures could potentially cause postoperative intraocular infection.

[Effect of antiseptic treatment of alveolar surgical wounds on bacterial growth on cotton suture threads]

The objective of this study was to evaluate bacterial growth on cotton suture. The efficiency of cetylpyridinium chloride (50%), hydrogen peroxide (3%) and chlorhexidine (0.12%) in antisepsis was investigated. For that, 20 patients who were submitted to extraction of impacted lower third molars were studied. Five days after extraction, samples were obtained from the oral and alveolar sides of the sutures, before and after antisepsis of the wounds, and were submitted to bacteriological analysis. Bacterial growth was observed in all examined samples. The number of streptococci decreased after antisepsis and there were no statistically significant differences between the methods of antisepsis used.

Rate of loss of irradiated polyglactin 910 (Vicryl Rapide) from the mouth: a prospective study

We aimed to find out how long irradiated polyglactin 910 (Vicryl Rapide) remained in the oral tissues and to investigate the effect of chlorhexidine mouthwash on absorption time and bacterial growth on sutures. Twenty-one volunteers each had two Vicryl Rapide sutures placed intraorally under local anaesthesia. Ten of these subjects used chlorhexidine mouthwash twice daily. After 7 days, one suture was removed to be cultured for aerobic and anaerobic bacteria. The other was monitored for time from insertion to loss. The median survival value was 3 days (range 1-13). The median number of days to suture loss was less in the chlorhexidine group (3, range 1-11) than in the control group (4, range 1-13) but this was not significant. There were no significant differences in aerobic and anaerobic counts between the two groups. Vicryl Rapide may be useful for intraoral use.

Oral tissue reactions to suture materials

Tissue reactions to natural and synthetic braided and monofilament suture materials in gingiva and oral mucosa were studied. A total of 138 sutures made of four commonly used materials were placed in the edentulous ridges and vestibular mucosa of eight beagle dogs. Biopsy specimens including the suture loop and surrounding tissues were obtained after 3, 7, and 14 days and processed for histologic analysis. The inflammatory reaction was more rapid and intense than the reaction that has been reported after suture placement in skin. Bacterial invasion of the suture track was a common sequela regardless of the material used, but it was particularly prominent for silk. The formation of a perisutural epithelial sleeve was well under way at 3 days and in some instances included the entire suture track within 7 days. Connective tissue reactions consisted of several well-defined, concentric perisutural zones. At 14 days, these zones were partly replaced by granulation tissue surrounded by a fibrous capsule. The synthetic monofilament suture elicited a mild inflammatory tissue response. The results showed that sutures placed in gingiva and oral mucosa produce a prolonged tissue response that is most likely a result of the continual influx of microbial contamination along the suture channel, which may be a lesser problem when sutures are placed in other surgical compartments. The results indicate that chromic gut sutures are rapidly and unpredictably absorbed when used in an environment characterized by moisture and infectious potential.