Infections caused by anaerobic bacteria are common, and may be serious and life-threatening. Anaerobes predominant in the bacterial flora of normal human skin and mucous membranes, and are a common cause of bacterial infections of endogenous origin. Infections due to anaerobes can evolve all body systems and sites. The predominate ones include: abdominal, pelvic, respiratory, and skin and soft tissues infections. Because of their fastidious nature, they are difficult to isolate and are often overlooked. Failure to direct therapy against these organisms often leads to clinical failures. Their isolation requires appropriate methods of collection, transportation and cultivation of specimens. Treatment of anaerobic bacterial infection is complicated by the slow growth of these organisms, which makes diagnosis in the laboratory only possible after several days, by their often polymicrobial nature and by the growing resistance of anaerobic bacteria to antimicrobial agents.

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Tuesday, January 29, 2013

Infectious Diseases Society of America guideline for the diagnosis and treatment of diabetic foot infections.

Foot infections are a frequent and serious problem in individuals with diabetes. The Infectious Diseases Society of America recently published clinical practice guideline for the diagnosis and treatment of diabetic foot infections.  Diabetic foot infections (DFIs) usually starts as a wound, most often a neuropathic ulceration. While all wounds are colonized with microorganisms, the presence of infection is defined by ≥2 classic findings of inflammation or purulence.
Infections are then classified into:

·       Mild (superficial and limited in size and depth).
·       Moderate (deeper or more extensive).
·       Severe (accompanied by systemic signs or metabolic perturbations).

This classification system, along with a vascular assessment, helps determine which patients should be hospitalized, which may require special imaging procedures or surgical interventions, and which will require amputation.
Most DFIs are polymicrobial infections caused by aerobic gram-positive cocci (GPC), and especially staphylococci, the most common causative organisms. Aerobic gram-negative bacilli are frequently copathogens in infections that are chronic or follow antibiotic treatment, and obligate anaerobes may be copathogens in ischemic or necrotic wounds.
The Guidelines stat that wounds without evidence of soft tissue or bone infection do not require antibiotic therapy. For infected wounds, they suggest obtaining a post-debridement specimen (preferably of tissue) for aerobic and anaerobic culture. Empiric antibiotic therapy can be narrowly targeted at GPC in many acutely infected patients, but those at risk for infection with antibiotic-resistant organisms or with chronic, previously treated, or severe infections usually require broader spectrum regimens.
According to the Guidelines imaging is helpful in most DFIs; plain radiographs may be sufficient, but magnetic resonance imaging is far more sensitive and specific. Osteomyelitis occurs in many diabetic patients with a foot wound and can be difficult to diagnose (optimally defined by bone culture and histology) and treat (often requiring surgical debridement or resection, and/or prolonged antibiotic therapy).
It is recommended that in most DFIs some surgical intervention, ranging from minor (debridement) to major (resection, amputation) is performed. Wounds must also be properly dressed and off-loaded of pressure, and patients need regular follow-up. An ischemic foot may require revascularization, and some nonresponding patients may benefit from selected adjunctive measures. Employing multidisciplinary foot teams improves outcomes. The guidelines encouraged clinicians and healthcare organizations to monitor, and thereby improve, the outcomes and processes in caring for DFIs.

Diabetic foot ulcer