Abstract
Abstract
Background:
Necrotizing fasciitis (NF) is usually caused by group A streptococcus, staphylococcus aureus, or Clostridium perfringens, although it is rare by gram negative bacteria. The management plan is similar irrespective of the organism causing it and always requires early detection of causative bacterial sensitivity, surgical debridement, and appropriate medication, which can minimize the chances of morbidity and mortality.
Methods:
A 39-year-old morbidly obese female presented with a necrotic wound in the right side of the panniculus that coursed for 7 mo. Debrided tissue cultures indicated presence of Pseudomonas aeruginosa with maximum number of isolates (n=54), followed by other gram negative organisms. Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score of 11 was recorded. On bacterial sensitivity, imipenem and piperacillin-tazobactam was infused after a massive surgical debridement.
Results:
Post-operatively, vitals were monitored closely and the wound dressing vacuum-assisted closure (VAC)® was routinely changed to assure an aseptic surgical site. A score of 4 was achieved on LRINEC in 27 d.
Conclusion:
Soft tissue infections and necrotizing fasciitis are not the main features of Pseudomonas aeruginosa and other isolates from the specimen. It was a perculiar presentation of the bacteria.
A 39-year-old diabetic female with multiple medical co-morbidities presented a right lower abdominal panniculus with necrotic wound. The first symptoms appeared 7 mo prior with erythema on the site with some edema, followed by a large black eschar. The eschar was eroding gradually through the soft tissue. The wound was an oval- shaped lesion with irregular non-healing margins and of partial thickness. The wound was 10 cm in vertical length and 20 cm in horizontal width with a depth of 2 cm. Some small capillary vasculature and clumping of fatty tissue was also observed in the wound. It was a stage III partial thickness wound (full thickness tissue loss). Subcutaneous fat may be visible but bone, tendon, or muscle are not exposed and non-odorous scant sero-puruluent exudate was observed at the wound site (Fig. 1). No tunneling, undermining, or sinus tracts were observed. The wound bed was firmly adherent soft yellow necrotic slough with some epithelialization at the irregular borders. Edematous tissue with erythema and pain on superficial palpation on the borders were also observed.
The pre-operative image showing ulcerated wound on abdominal panniculus of dimensions approximately 10 cm×20 cm. The lesion depth is of 2 cm with a necrotic fat floor. The erythema extends to right lateral side and involving the anterior right thigh and right groin crease. Petechial hemorrhages are observed as well. Wound contracture on the margins of the lesion is prominent. Foley's catheter is placed.
Broad spectrum antibiotics covering anaerobes were administered intravenously. Laboratory Risk Indicator for Necrotizing Fasciitis score was 11 recorded prior to surgery. Debrided tissue cultures showed Pseudomonas aeruginosa, Acinetobacter baumannii, and traces of Stenotrophomonas maltophilia were identified.
Pseudomonas aeruginosa had the greatest number of bacterial isolates (n=54) from the debrided tissue. Sensitivity of the isolated microbes was done on the antibiotic panel, which showed imipenem and piperacillin-tazobactam as the best choices to treat P. aeruginosa and A. baumannii. No antibiotic percentage was satisfactory enough to be prescribed for covering S. maltophilia, although amikacin had the greatest percentage of sensitivity for it.
Total debridement of the tissue along with margins was done and negative pressure wound therapy was suggested that works by wound vacuum-assisted closure (VAC). This therapy works by delivering negative pressure (a vacuum) on the wound site through a patented dressing, which draws wound edges together, removes infectious materials, and actively promotes granulation. Close monitoring of vitals was done along with renewing the dressing of wound VAC every fifth day.
The LRINEC score dropped to 4 in a course of 27 d, promising to decrease the chances of mortality. The patient was stabilized and shifted to conservative therapy including fluid resuscitation, renewing wound dressing, and physical rehabilitation.
Discussion
Necrotizing fasciitis is a medical emergency that requires extensive fluid replacement and surgical debridement with intravenous broad spectrum antibiotics and immunoglobulins, depending on the severity of the disease. A surgical approach becomes necessary in most cases and should be done in the early phase of the disease. A simple way to differentiate NF from other soft tissue diseases and cellulitis is by LRINEC score. A score equal to or above 6 is considered as NF. Laboratory Risk Indicator for Necrotizing Fasciitis scoring consists of a total of six markers: C-reactive protein, white blood cells, hemoglobin, sodium, serum glucose, and creatinine. The score is established according to the levels of these markers and is an easy, quick, and externally validated method [see Table 1].
LRINEC Scoring System for Necrotizing Fasciitis Uses Six Markers; Each Marker Is Scored According to Its Level
Diseases and drugs that suppress the immunity are the contributory factors for this condition. If not treated adequately this condition can lead to extension into the adjacent tissues from the focal origin site and prove to be fatal. Group A streptococcus, C. perfringes, and S. aureus are the most common organisms causing NF. The disease is classified as Type I (monomicrobial) or Type II (polymicrobial). The latter is more common.
A study determined that a LRINEC score ≥6 had a sensitivity of approximately 90% and a specificity of approximately 95%, PPV 92%, and NPV 95%. A LRINEC score of ≥6 could be used potentially as a tool to rule in necrotizing fasciitis, but a score <6 should not be used to rule out the diagnosis [1].
A study done in Turkey in 2012 reviewed the cases of NF that resulted in significant conclusions. The majority of NF cases had already co-morbid conditions such as obesity, diabetes mellitus, corticosteroid use, and smoking. The perineum and inguinal region were the most commonly involved sites. This study also showed that polymicrobial etiology is more common as mentioned before. Escherichia coli and P. aeruginosa were the only organisms reported from gram negative bacteria family, though major isolates were gram positive. It was important to note surgically that more than half of the cases required a fasciocutaneous flap plus split-thickness grafting. A mortality rate of 13.2% was noted from this review [2].
Another review of NF in extremities was done in Taiwan, which showed gram negative vibrio spp. was more common. Overall, this review suggested monomicrobial-type NF was more prevalent. The majority of cases were of the lower extremity, and most of the cases in this review received fasciotomy as the immediate surgical intervention. Klebsiella pneumoniae was associated with the greatest mortality [3].
Three cases of lower limb NF in leukemia patients were reported in Taiwan in 2011. Presenting complaints were fever along with pain in the lower extremity without any history of trauma, open wound, or other obvious sources of infection. All of the patients were on chemotherapy and had indwelling catheters, which were considered a possible source of infection. Each of the patients had severe neutropenia. Empiric antibiotics including carbapenems and cephalosporins were given. Before any surgical intervention could take place, the patients either went into shock or died. Aeromonas sobria, a water borne gram-negative rod, was found to be the causative agent in all of these cases. The bacterial isolates from tissue specimens showed quinolone sensitivity. Progression of the disease was rapid with 100% mortality occurring within few days [4].
There are a few considerations for physicians and surgeons prior to making decisions for treatment of NF patients. The first and foremost is the appropriate excision of the site with replenishing of fluids; second, culture sensitivity of the bacteria that can assist in focused antibiotic therapy; and last, involvement of a multi-dimensional approach demanding the involvement of experts of infectious diseases and an intensive care unit team, whenever necessary. Focused and timely management can reduce morbidity and mortality of NF patients.
Footnotes
Author Disclosure Statement
No competing financial interests exist.