DISCUSSION

Decubitus ulcers are prone to infection, and the growing agent varies according to the location, and may frequently be polymicrobial. The most commonly isolated bacteria are staphylococci, enterococci, Proteus mirabilis, Escherichia coli and P. aeruginosa; along with anaerobic bacteria, peptostreptococci, Bacteriodes fragilis and clostridium species. Bacteria on the surface of the skin may invade the underlying tissue and cause infection. Signs of sepsis and cellulitis, and osteomyelitis due to sepsis, may be seen [4, 8].
The diagnosis of decubitus ulcer infection is challenging. A good microbiological and clinical evaluation, in addition to imaging studies and deep tissue biopsy, are recommended [11]. A clinical examination is important for the determination of decubitus ulcers as occult foci of infection. Increased temperature, erythema, local tenderness, bad odor and purulent discharge are valuable signs during a clinical evaluation. Although tissue biopsy samples and aspiration fluid cultures have been recommended for the microbiological diagnosis of decubitus ulcer infection, they are not generally preferred due to the difficulty in clinical use and their invasive nature [4, 11]. The obtaining of bacterial swab cultures is a noninvasive procedure that provides preliminary knowledge on the bacterial density of the wound. Surface wound cultures show colonization rather than infection, although the colonizing bacteria may cause local infection if they continue to proliferate, delaying wound healing [12]. The rate of bacteremia due to the decubitus ulcers was found to be 13.9% in our study, but was reported to be higher in another study [3]. This difference may be attributable to the stages of the wounds in the studies, as the frequency of bacteremia may be higher in advanced stages. There was a large number of patients with stage 3 wounds in the present study.
Bacterial contamination on the surface of decubitus ulcers is common, and such contaminations, in turn, may lead to serious life threatening problems such as bacteremia and sepsis by diffusing into deep tissues, resulting in infection [4]. Bacteremia due to decubitus ulcers should be considered in patients presenting with fever and with no other focus of infection. The optimum approach to the diagnosis of wound site infection is tissue biopsy or aspiration [13]. Sterile swabs were used in this present study, given their non-invasive ease of use.
The most common colonizing microorganisms in decubitus ulcers are gram negative bacteria such as acinetobacter baumanni, pseudomonas aeruginosa and enterobacteriaceae, and staphylococcus aureus. The frequency of infection and/or colonization by microorganisms with multi-drug resistance is increasing gradually in decubitus ulcers. Aerobic cultures generally reveal methicillin resistant S. aureus or multi drug resistant gram negative bacilli, and may lead to local and systemic infection [12].
The sacrum was the most common location for decubitus ulcers in the present study, concurring with other studies in literature [8, 14, 15]. The reason for this may be the elevated head position of patients due to alleviate the risks associated with aspiration. The risk of infection has been reported to be high in stage 3–4 decubitus ulcers [4]. In line with previous studies, most decubitus ulcers were found to be stage 3 [4]. Due to the high risk of infection, the prevention of colonization in stage 3 and 4 decubitus ulcers may decrease the risk of infection and bacteremia.
Decubitus ulcer-associated bacteremia was identified in 16 of the 21 patients in the study by Jeffrey et al. [7], while decubitus ulcer-associated bacteremia was found in six out of the 27 patients with decubitus ulcers in the study by Peromet et al. [16]. The rate of bacteremia in decubitus ulcers was 53,6%. [3]
In our study, the incidence of polymicrobial bacteremia was found to be increased in accordance with the literature. [6-8].
No clinical or epidemiological sign is present for the prediction of the causative agent of bacteremia in chronic wounds, since the local infection of decubitus ulcers is polymicrobial, and the risk of colonization with new microorganisms is high. Microorganisms of the flora may grow in the cultures. [17] Accordingly, as a starting antibiotherapy, agents with antimicrobial effects against staphylococcus aureus, gram negative enteric bacilli and anaerobic microorganisms, including Bacteroides fragilis, taking into account also local resistance rates, should be considered [14]. Antibiotic treatment should be adjusted based on blood culture results. [8]
The most commonly isolated bacteria were gram negative enteric bacteria (klebsiella and e. coli), followed by staphylococcus aureus in second place, and pseudomonas and acinetobacter in third place. A vast majority of the patients were transferred from hospital beds and had previously been admitted to the intensive care unit. In addition to the bacteria that cause bacteremia, many factors such as the patient’s age, immune status, comorbid conditions, feeding, hospitalization period, frequency of interventional procedures etc. are effective. [18].