Eradication of methicillin-resistant Staphylococcus aureus in a chronic wound by a new polyhexanide hydrogel

Can dressings soaked with polyhexanide reduce bacterial loads in full-thickness skin grafting? A randomized controlled trial

BACKGROUND

Polyhexamethylene biguanide (PHMB)-based antiseptic solutions can reduce bacterial loads in different clinical settings and are believed to lower risk of infections.

OBJECTIVE

We sought to assess the efficacy of a PHMB-based solution in lowering bacterial loads of full-thickness skin grafting wounds and the risk of surgical site infections (SSIs).

METHODS

In this double-blinded clinical trial, 40 patients planned for facial full-thickness skin grafting were randomized 1:1 to receive tie-over dressings soaked with either PHMB-based solution or sterile water. Quantitative and qualitative bacterial analysis was performed on all wounds before surgery, at the end of surgery, and 7 days postoperatively. In addition, all patients were screened for nasal colonization of Staphylococcus aureus.

RESULTS

Analysis of wounds showed no statistically significant difference in bacterial reductions between the groups. The SSI rates were significantly higher in the intervention group (8/20) than in the control group (2/20) (P = .028). Higher postoperative bacterial loads were a common finding in SSIs (P = .011). This was more frequent when S aureus was present postoperatively (P = .034), intraoperatively (P = .03), and in patients with intranasal S aureus colonization (P = .007).

LIMITATIONS

Assessment of SSIs is largely subjective. In addition, this was a single-center study and the total number of participants was 40.

CONCLUSION

Soaking tie-over dressings with PHMB solution in full-thickness skin grafting had no effect on postoperative bacterial loads and increased the risk of SSI development. The presence of S aureus intranasally and in wounds preoperatively and postoperatively increased postoperative bacterial loads, which in turn resulted in significantly more SSIs.

In-vitro activity of polyhexanide alone and in combination with antibiotics against Staphylococcus aureus

BACKGROUND

The resistance of Staphylococcus aureus is increasing, not only to antibiotics but also to antiseptics.

AIM

To investigate the activity of the antiseptic polyhexanide and several antibiotics against clinical isolates of meticillin-susceptible and meticillin-resistant Staphylococcus aureus (MSSA and MRSA, respectively). Polyhexanide was tested alone and in combination with oxacillin, penicillin G, ampicillin, cefazolin, cefuroxime, imipenem, gentamicin, erythromycin, doxycycline, levoflocaxin, linezolid and vancomycin.

METHODS

Fifty MSSA and 50 MRSA strains, including one vancomycin-intermediate (VISA) strain, were tested. All strains were typed by pulsed-field gel electrophoresis (PFGE) to exclude testing of clonal isolates. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined using the serial broth microdilution technique according to DIN 58940. Combinations of polyhexanide and different antibiotics were investigated using the checkerboard technique.

FINDINGS

Polyhexanide MICs and MBCs in the range of 0.5-2mg/L were found for both MSSA and MRSA, and the VISA strain had MIC and MBC values of 2mg/L. All isolates were regarded as susceptible to polyhexanide, and no antagonism was observed between polyhexanide and the tested antibiotics. Synergism between polyhexanide and some bacteriostatic antibiotics (erythromycin, doxycycline and linezolid) was found for some strains.

CONCLUSIONS

Polyhexanide appears to be suitable for the topical treatment of S. aureus alone and in combination with antibiotics.

Activity of the antiseptic polyhexanide against meticillin-susceptible and meticillin-resistant Staphylococcus aureus

Staphylococcus aureus is one of the most important pathogens, with increasing emergence of meticillin-resistant S. aureus (MRSA) strains. This is associated not only with multiresistance to antibiotics but also with increasing resistance to topical antibiotics and antiseptics. As the antiseptic polyhexanide has only a low risk of emergence of resistant strains, the aim of the study was to obtain data on the sensitivity of S. aureus towards polyhexanide. The effect of polyhexanide was tested against 80 meticillin-susceptible S. aureus (MSSA) and 80 MRSA strains from sporadic cases as well as against 6 MRSA outbreak strains. The clonal diversity of the 166 strains was proven by pulsed-field gel electrophoresis (PFGE). Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined by the serial broth microdilution technique according to DIN 58940. Time-kill studies were performed for reference strains MSSA ATCC 29213 and MRSA ATCC 33591. MICs and MBCs in the range of 0.5-2mg/L were found. According to a created epidemiological cut-off (ECOFF) value of 4mg/L, all strains were regarded as susceptible to polyhexanide, including MRSA epidemic strains and MSSA and MRSA sporadic strains with various antibiotic susceptibility patterns. Addition of up to 4% albumin to the test medium did not change the MICs and MBCs. Time-kill studies showed reduction rates of 4log₁₀CFU/mL for 200mg/L and 5log₁₀CFU/mL for 400mg/L polyhexanide within 5-30min. It is concluded that polyhexanide is suitable for topical eradication of S. aureus.

MRSA eradication in dermatologic outpatients - theory and practice

BACKGROUND

The dissemination of methicillin resistant staphylococcus aureus (MRSA) is an increasing challenge in medical care. Apart from hospital acquired MRSA, there has also been an increase in community acquired and livestock associated MRSA. While the risks of MRSA (e. g. wound infections) and consequences (e. g. rejection of patients) are well known, there are little data on the effectiveness of eradication procedures.

PATIENTS AND METHODS

32 patients with proven MRSA colonization were monitored during eradication for the following aspects: (1) localization of MRSA (swabs from hairline, anterior nares, throat, axillae, groins, perineum, and wounds, if present), (2) presence of eradication-impairing factors, (3) length of time needed for eradication, (4) cost of eradication, (5) molecular fingerprint and risk assessment (spa-types).

RESULTS

We describe the successful eradication of MRSA in all 32 patients. Most positive nasal swabs were obtained from the anterior nares and the throat and only rarely from the hairline or axillae. The greater the number of positive swabs, the more time was needed for eradication. In most patients (37.5%), eradication with topical antiseptics was successful. The average time for eradication was 12.97 (± 7.6) days. Twelve patients required systemic antibiotic therapy. Treatment costs associated with the use of systemic antibiotics were significantly higher. The most frequent spa types were t032 and t003.

CONCLUSIONS

We report successful MRSA eradication in outpatients. Systemic antibiotics are unnecessary in the majority of patients. A combined anti-MRSA strategy for inpatients and outpatients is recommended.

Influence of antiseptics on microcirculation after neuronal and receptor blockade

The topical application of the antiseptics octenidine and polyhexanide on wounds seems to improve microcirculation. These two antiseptics were tested in combination with neuronal inhibition and sympathethic receptor blockade to verify these findings, explore the influence of β blockers on these microcirculative effects, and find out the principle of operation. Investigations were carried out on a standardised cremaster muscle model in rats (n = 66). The tested antiseptics, octenidine and polyhexanide were investigated alone (n = 12) and in combination with bupivacaine (n = 12), metoprolol (n = 12), phentolamine (n = 12) and surgical denervation (n = 12). Physiological saline was used for control (n = 6). The arteriolar diameter and functional capillary density (FCD) were investigated via trans-illumination microscopy before, as well as 60 and 120 minutes after application. Polyhexanide caused a significant increase in arteriolar diameter (86·5 ± 3·8 µm versus 100·0 ± 3·6 µm) and, like octenidine (7·2 ± 0·7 n/0·22 mm(2) versus 11·6 ± 0·6 n/0·22 mm(2) ), in FCD (9·2 ± 0·5 versus 12·6 ± 0·9) as well. When the antiseptics are used in combination with bupivacaine, metoprolol, phentolamine or surgical sympathectomy, these effects were eliminated or inverted. Assessing the results of the different blockades in combination with polyhexanide, we surmise that the antiseptic polyhexanide acts on the microcirculation mainly by blocking α receptors. This study shows that polyhexanide and octenidine improve muscular perfusion. Interestingly, the benefit of polyhexanide and octenidine on muscular perfusion is eliminated when the antiseptics are combined with other vasoactive agents, especially β blockers.

Efficacy of intraoperative surgical irrigation with polihexanide and nitrofurazone in reducing bacterial load after nail removal surgery

BACKGROUND

A common challenge of nail avulsion surgery is the associated bacterial contamination and infection that can manifest. The toe has a difficult anatomy to antiseptically prepare and properly maintain throughout the surgical procedure, lending to this widespread problem.

OBJECTIVE

We conducted a controlled, prospective randomized study to examine the antiseptic efficacy of 3 intraoperative irrigation methods during nail avulsion surgery.

METHODS

We compared intraoperative antiseptic irrigation using 0.9% saline solution (24 patients), 0.2% nitrofurazone (22 patients), and 0.1% polihexanide (25 patients). Swab samples were taken from each patient at 5 distinct stages throughout the surgical procedure, and bacterial culture analysis was performed (positive culture rate, total inocula count, reduction of bacterial load, and identification of specific micro-organisms).

RESULTS

All 3 intraoperative irrigation methods reduced the total bacterial load, but polihexanide was significantly more effective. Furthermore, no patient from the polihexanide group developed postoperative infection. The reduction in bacterial load was lost for all 3 methods after partial nail avulsion surgery, returning to similar values as the initial presurgical bacterial load. An intraoperative irrigation step after partial nail avulsion with saline, nitrofurazone, and polihexanide was effective in reducing the bacterial load by 95.2%, 96.6%, and 99.5%, respectively.

LIMITATIONS

Our patients underwent phenol-based nail avulsion, resulting in no bacterial load after complete nail removal because of the intrinsic antiseptic nature of the phenol.

CONCLUSIONS

Intraoperative irrigation with 0.1% polihexanide substantially reduced the bacterial load and subsequent infections, highlighting the importance of an irrigation step in nail avulsion surgery.

Wound cleansing, topical antiseptics and wound healing

Quality of care is a critical requirement for wound healing and 'good' care of wounds has been synonymous with topical prevention and management of microbial contamination. Topical antiseptics are antimicrobial agents that kill, inhibit or reduce the number of microorganisms and are thought to be essential for wounds infection control. However, they have long and commonly been used on wounds to prevent or treat infection, the merits of antiseptic fluid irrigation have received little scientific study. Unlike antibiotics that act selectively on a specific target, antiseptics have multiple targets and a broader spectrum of activity, which include bacteria, fungi, viruses, protozoa and even prions. Although certain skin and wound cleansers are designed as topical solutions with varying degrees of antimicrobial activity, concerns have been raised. Wound cleansers may affect normal human cells and may be antimitotic adversely affecting normal tissue repair. Repeated and excessive treatment of wounds with antiseptics without proper indications may have negative outcomes or promote a microenvironment similar to those found in chronic wounds. However, when applied at the proper times and concentrations, some classes of antiseptics may provide a tool for the clinician to drive the wound bed in desired directions. The present review summarises the various antiseptics in use and their negative impact on the wound healing mechanisms. It is clear that the role of antiseptics on wounds and their role in wound care management need to be reconsidered.

Comparison of octenidine dihydrochloride (Octenisept®), polihexanide (Prontosan®) and povidon iodine (Betadine®) for topical antibacterial effects in Pseudomonas aeruginosa-contaminated, full-skin thickness burn wounds in rats

Pseudomonas aeruginosa is one of the most frequently isolated organisms from infected burn wounds and a significant cause of nosocomial infection and septic mortality among burn patients. In this animal study, three antiseptic agents which were Octenidine dihydrochloride (Octenisept®, Schülke & Mayr, Norderstedt, Germany), polyhexanide (Prontosan®, B. Braun, Melsungen AG, Germany) and povidon iodine (Betadine, Purdue Pharma L.P, Stamford, USA) were compared to assess the antiseptic effect of their applications on experimental burn wounds in in rats contaiminated with P. aeruginosa. All treatment modalities were effective against P. aeruginosa because there were significant differences between treatment groups and control groups. The mean eschar concentrations were not different between polyhexanide and povidon iodine groups, but there were significant differences between the octenidine dihydrochloride group and the other treatment groups, indicating that the Octenidine dihydrochloride significantly eliminated P. aeruginosa more effectively in the tissues compared to the to other agents. All treatment modalities were sufficient to prevent the P. aeruginosa invasion into the muscle and to cause systemic infection. In conclusion, Octenidine dihydrochloride is the most effective antiseptic agent in the treatment of the P. aeruginosa-contaminated burn wounds; Octenidine dihydrochloride can be considered as a treatment choice because of its peculiar ability of limit the frequency of replacing wound dressings.