The most common ulcers of the lower extremities are of venous etiology, ie about 80% of all leg wounds belong to venous ulcers [1]. Healing venous ulcers is a real challenge for doctors, especially chronic wounds that affect the quality of life of patients. Treatment of venous ulcers is often complicated, especially if there are other factors that make treatment difficult for patients. The existence of a positive microbiological finding from a venous ulcer is considered normal, and according to some authors should not be considered when it comes to delayed healing of ulcers [2]. However, some authors point out that the treatment of symptomatic infection affects the process of closing the ulcer and reducing its duration [3]. Ulcers can be colonized by different bacterial species at the same time. The most common Gram-positive bacterium that can be found in the ulcer is Staphylococcus aureus, while the Gram-negative bacteria are Pseudomonas aeruginosa and Escherichia coli. Positive swabs of Proteus mirabilis, Klebsiella pneumonia, Morganella morganii, Klebsiella oxytoca, Coagulase-negative Staphylococcus are also common [4]. Most of the bacteria isolated from venous ulcers are considered to be resistant to antibiotics due to their overuse during treatment and when there is no indication. The use of systemic antibiotics is recommended only in wounds with symptomatic infection.

Half of patients with isolated S. aureus from hospitalized dermatological patients with venous ulcers have been shown to be resistant to methicillin (MRSA) and more than one-third of P. aeruginosa isolates are resistant to ciprofloxacin. MRSA is much more common in patients who have previously received a broad-spectrum antibiotic without a swab and an antibiogram. The use of antibiotics in venous ulcers without proper indication shows increased resistance to bacteria that later multiply in the wound and complicates it, which is why today some of the most resistant bacteria can be isolated from lower extremity ulcers from these patients [5].

The study included 105 patients with venous ulcer of the lower extremities, 39 of whom were found to have a symptomatic presence of secondary bacterial colonization. In some of them, the presence of the pathogen was confirmed with a microbiological swab, while in patients who had previously received antibiotic therapy, the presence of clinical signs of infection such as pain, edema, purulent discharge, unpleasant odor, and laboratory tests were performed and show increased C-reactive protein, increased erythrocyte sedimentation rate, and increased white blood cells. In some of the patients, an ultrasound was performed which showed the presence of reactive lymph nodes. All patients were followed for 12 weeks. All underwent the same treatment, with the exception of patients with confirmed infection where an antibiogram or broad-spectrum antibiotic was included. We monitored the duration of the ulcer in patients without signs of infection and in patients with confirmed venous ulcer infection

For p <0.0001, a statistically significant difference was confirmed in the incidence of secondary bacterial infection between patients with delayed and normal healing of ulcers. Significantly more frequent finding of secondary bacterial colonization was registered in patients with delayed healing, i.e. in patients who did not close 12 weeks from the start of treatment; 36 (60%) patients in the delayed recovery group and only 3 (6.7%) patients in the normal recovery group had a secondary bacterial infection (Table 1).

Table 1: Ulcus duration in patients with and without infection.

Figure 1: Ulcus duration in patients with and without infection.

In 13 (36.1%) patients with delayed ulcer closure, a positive wound swab was found. The table shows the structure of the isolated causes of secondary bacterial infection (Table 2).

Table 2: Microbiological swab.

Infection as determined by clinical picture and laboratory findings was reported in 23 (38.3%) patients in whom the ulcer closed for 12 weeks or longer, and in only 2 (4.4%) patients in whom the ulcer closed in less than 12 weeks. The more frequent finding of clinically and laboratory-diagnosed secondary bacterial infection in patients with delayed venous ulcer healing was also confirmed statistically, with a significance of p = 0.000055 (Table 3).

Table 3: Normal and delayed ulcer healing - distribution according to clinically and laboratory-confirmed infection.

X2 (Pearson Chi-square)   ***p<0.0001

Figure 2: Normal and delayed ulcer healing - distribution according to clinically and laboratory-confirmed infection.

In our study, secondary bacterial colonization was proven in 39 patients or 37.14% of the subjects, and several specifics E.coli, MRSA, Klebsiela, P.aeruginosa, S.aureus, S.coagulaza, P.mirabilis were confirmed. The presence of these strains was accompanied by a characteristic clinical picture, and their existence proved to be an important prognostic factor for the therapeutic response to venous ulcer. Of the group of patients with delayed ulcer healing, 60% have proven secondary bacterial colonization. The most common pathogen among our subjects was S. aureus. The end result of the healing of these wounds was the formation of a hyperpigmented scar.  However, delayed ulcer healing is considered to be present if there is an increase in bacterial colonization and cellulitis, which is an individual characteristic.

Taking a microbiological swab and giving an antibiotic after an antibiogram in patients with symptomatic venous ulcer infection has been shown to be most important. Antibiotics should not be prescribed to all patients with venous ulcers because we increase the potential for the emergence of resistant pathogens in the wound, and thus delay healing. Signs of pre-existing venous ulcer infection further complicate treatment and outcome. Infected wounds increase the duration of the ulcer, and thus reduce the quality of life of these patients. Microbial colonization may impair the healing of the ulcer.

1. Probst, S, Weller CD, Bobbink P, saini C, Pugliese M, Skinner MB, et al. Prevalence and incidence of venous leg ulcers a protocol for a systematic review: Syst Rev. 2021; 148.
2. Dogra S, Sarangal R. Summary of recommendations for leg ulcers: Indian Dermatol Online J. 2014; 5: 400-407.
3. Ren SY, Liu YS, Zhu GJ, Liu M, Shi HS, Ren XD, et al. Strategies and challenges in the treatment of chronic venous leg ulcers. World J Clin Cases. 2020; 8: 5070-5085.
4. Cwajda-Bialasik J, Moscicka P, Jawien A, Szewczyk MT. Microbiological Status of Venous Leg Ulcers and Its Predictors: A Single Center Cross Sectional Study. Int. J. Environ. Res Public Health. 2021; 18: 12965.
5. Howell-Jones RS, Wilson M J, Hill KE, Howard AJ, Price PE, Thomas DW. A review of the microbiology, antibiotic usage and resistance in chronic skin wounds: Journal of Antimicrobial Chemotherapy. 2005; 55: 143-149