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].