1. PRESURE ULCER
Pressure ulcers cause pain, decrease quality of life, and lead to significant morbidity and prolonged hospital stays, in part due to complicating infection. Infected pressure ulcers are a common problem, occurring in 4 to 6 percent
Colonization  — Colonization of the pressure ulcer by microorganisms precedes the development of infection. The ulcer is first colonized with skin flora, which is rapidly replaced by bacteria from the local environment and the urogenital or gastrointestinal tracts, often from direct fecal contamination

2. High concentrations of bacteria in pressure ulcers inhibit normal wound healing and promote infection. In one study, delayed healing of pressure ulcers occurred when bacterial counts were >10(5) colony forming units (CFU) per gram of tissue
MICROBIOLOGY  — The microbiology of pressure ulcers is similar whether the ulcer is superficial or deep. Nearly all infected pressure ulcers reveal multiple organisms when cultures are obtained

3. The predominant organisms were Enterobacter (29 percent), staphylococci (28 percent) and Enterococcus faecalis (16 percent).
The major organisms were staphylococci (including methicillin-resistant Staphylococcus aureus [MRSA], methicillin-susceptible S. aureus, and coagulase-negative staphylococci), streptococci, Proteus mirabilis, and anaerobes
Common culture techniques include quantitative swab culture, needle aspiration, and tissue or bone biopsy.

4. Aerobes that are commonly recovered include staphylococci,enterococci, Proteus mirabilis, E. coli, and Pseudomonas spp.
Anaerobic; Peptostreptococcus, Bacteroides fragilis, and Clostridiumspp. are frequently isolated from the infections
Bacteremia in this situation is usually caused by P. mirabilis,S. aureus, or B. fragilis

5. for infection control practices, a swab culture may be useful in identifying patients colonized with MRSA or other resistant bacteria
physicians may have only the swab culture results to guide antibiotic selection in patients with signs of infection that are unable or unwilling to undergo a surgical procedure for tissue or bone biopsy.
blood culture or a culture of a deep-tissue biopsy specimen is more clinically significant than culture from a superficial swab specimen

6. needle aspiration from below the ulcer margin to those recovered by tissue biopsy (concordance between the aspirate and biopsy cultures with a sensitivity of 93 percent and a specificity of 99 percent.)
(local anesthesia should not be used because of potential antibacterial activity)
Culturing deep tissue specimens sampled from a surgically cleaned and debrided ulcer remains the gold standard for wound culture

7. DEEP INFECTION
  Deep infection includes ulcers complicated by cellulitis, osteomyelitis, bacteremia, and/or sepsis, and requires systemic antimicrobial therapy
Cellulitis  
Patients with sensory neuropathy often do not experience pain in the setting of cellulitis.
differentiate cellulitis from maceration of pressure ulcer wound edges is very difficult

8. Osteomyelitis
present as a poorly healing wound with or without systemic manifestations 
There were no clinical signs or symptoms that correlated with a final diagnosis of osteomyelitis, including the presence of fever, bone exposure, duration of the ulcer, purulent drainage, leukocytosis, or elevated erythrocyte sedimentation rate.

9. Complications of unrecognized osteomyelitis include flap reconstruction failure, sepsis, and bacteremia.
Bacteremia
with or without clinical signs of sepsis (eg, unexplained fever, tachycardia, hypotension, and/or deterioration in mental status
When pressure ulcers do cause bacteremia, they have been associated with high mortality rate 

10. Other complications:
septic arthritis, endocarditis, and meningitis

11. Psychosocial consequences are not often considered
Psychosocial consequences are not often considered. However, patients with pressure ulcers suffer pain and suffer a loss of control over their lives. Wound care disrupts normal activities of daily life and patients often feel stigmatized. This results in lifestyle changes leading to social isolation, depression and decrements in overall health-related quality of life.The extent and magnitude of psychosocial complications have not been well defined in the literature.

12. Pressure ulcers may also pose a risk to other hospitalized patients by serving as a reservoir for resistant organisms such as methicillin-resistant Staphylococcus aureus, vancomycin- resistant enterococci, and multiply-resistant gram negative bacilli

13. other complications  — Other complications due to pressure ulcers are rare.
Sinus tracts may develop that communicate with the deep viscera including the bowel or bladder.
Heterotrophic calcification occurs occasionally.
The chronic inflammatory state arising from the ulcer may result in systemic amyloidosis.
Squamous cell carcinoma occasionally develops in a pressure ulcer and should always be considered in patients with a nonhealing wound