Pediatric surgical site and soft tissue infections

OBJECTIVE

The purpose of this review is to provide background and a concise set of definitions for pediatric surgical site and wound infections.

DESIGN

The information discussed in this report is derived from a literature review and discussion at an international consensus conference on pediatric sepsis.

MEASUREMENTS AND MAIN RESULTS

There is a paucity of literature on pediatric surgical site and wound infection definitions. Excluding burn wounds, surgical site and wound infections rarely lead to overwhelming sepsis. Nevertheless, surgical site or wound infections including pressure ulcers can lead to significant morbidity in the pediatric critical care setting.

CONCLUSIONS

Although surgical site and wound infections rarely lead to intensive care unit admissions, definitions are still valuable for stratifying potential candidates for sepsis trials.

Influence of ceftriaxone treatment on FDG uptake--an in vivo [18F]-fluorodeoxyglucose imaging study in soft tissue infections in rats

Our aim was to determine the influence of antibiotic treatment using ceftriaxone on [18F]-fluorodeoxyglucose (FDG) uptake in experimental soft tissue infections. PET scans were performed in two groups (treated n=4; non-treated n=4) at days 3, 5, and 6 after inoculation of the infection. Additional autoradiography was performed in four animals at day 7 and in three animals at day 11. The difference of FDG uptake on day 5 (after three days of antibiotic treatment) between both groups proved to be significant (df=6; T=2.52; p=0.045). FDG uptake determined at the other days did not reveal significant difference between the two groups. It seems to be possible that the effect of antibiotic treatment on FDG uptake is less evident than reported for therapy monitoring of cancer treatment. The change of FDG uptake over time in treated and untreated infections is complex and further in vivo experiments have to be initiated to investigate the potential value of clinical FDG PET in therapy monitoring of infection.

Predictors of mortality and limb loss in necrotizing soft tissue infections

HYPOTHESIS

Necrotizing soft tissue infections are associated with a high mortality rate. We hypothesize that specific predictors of limb loss and mortality in patients with necrotizing soft tissue infection can be identified on hospital admission.

DESIGN

A retrospective cohort study.

SETTING

A tertiary care center.

PATIENTS

Patients with a diagnosis of necrotizing soft tissue infection during a 5-year period (1996-2001) were included. Patients were identified with International Classification of Diseases, Ninth Revision hospital discharge diagnosis codes, and diagnosis was confirmed by medical record review.

INTERVENTIONS

Standard current treatment including early and scheduled repeated debridement, broad-spectrum antibiotics, and physiologic and nutritional support was given to all patients.

MAIN OUTCOME MEASURES

Limb loss and mortality.

RESULTS

One hundred sixty-six patients were identified and included in the study. The overall mortality rate was 16.9%, and limb loss occurred in 26% of patients with extremity involvement. Independent predictors of mortality included white blood cell count greater than 30 000 x 10(3)/microL, creatinine level greater than 2 mg/dL (176.8 micromol/L), and heart disease at hospital admission. Independent predictors of limb loss included heart disease and shock (systolic blood pressure <90 mm Hg) at hospital admission. Clostridial infection was an independent predictor for both limb loss (odds ratio, 3.9 [95% confidence interval, 1.1-12.8]) and mortality (odds ratio, 4.1 [95% confidence interval, 1.3-12.3]) and was highly associated with intravenous drug use and a high rate of leukocytosis on hospital admission. The latter was found to be a good variable in estimating the probability of death.

CONCLUSIONS

Clostridial infection is consistently associated with poor outcome. This together with the independent predictors mentioned earlier should aid in identifying patients on hospital admission who may benefit from more aggressive and novel therapeutic approaches.

Imaging of Macrophages in Soft-Tissue Infection in Rats: Relationship between Ultrasmall Superparamagnetic Iron Oxide Dose and MR Signal Characteristics

PURPOSE

To describe dose-dependent signal intensity (SI) characteristics of experimentally induced soft-tissue abscesses on 1.5-T T1- and T2*-weighted magnetic resonance (MR) images obtained 24 hours after administration of ultrasmall superparamagnetic iron oxide (USPIO) and to describe the relationship between SI and amount of USPIO uptake and macrophage iron content.

MATERIALS AND METHODS

Local institutional review committee on animal care approved the experiments, which were performed according to the guidelines of the National Institutes of Health and the committee on animal research at our institution. Unilateral calf muscle abscesses were induced in 21 rats with an injection of a Staphylococcus aureus suspension. The rats were divided into three groups of seven animals each: low USPIO dose (50 micromol of iron per kilogram of body weight), high USPIO dose (150 micromol Fe/kg), and control (saline solution). All rats were imaged before and 24 hours after USPIO administration at 1.5 T (transverse T1-weighted spin-echo, T2*-weighted fast gradient-echo, and short inversion time inversion-recovery sequences). Images were analyzed quantitatively and qualitatively with regard to SI and signal pattern. Temporal variation of calculated contrast-to-noise ratios was analyzed with the Wilcoxon signed rank test. MR findings were correlated with histopathologic findings, including those of electron microscopy.

RESULTS

Twenty-four hours after USPIO administration in the high-dose group, susceptibility effects were present in abscess periphery on postcontrast T2*-weighted images (P=.04), and SI enhancement was noted on postcontrast T1-weighted images within both abscess wall and abscess center (P=.04 for both). In the low-dose group, SI enhancement was noted in entire abscess on T1-weighted postcontrast images (P=.03). Neither significant SI loss (P=.09) nor susceptibility effects were detected in periphery or center of any abscess on postcontrast T2*-weighted images. There was no obvious difference in total amount of macrophages among the groups, but there was a clear difference with regard to individual iron content of iron-positive macrophages between the USPIO dose groups.

CONCLUSION

At 1.5 T, SI characteristics of abscesses on T1- and T2*-weighted images obtained 24 hours after USPIO injection strongly depend on administered dose of the contrast agent. At low doses, T1 effects were stronger than T2* effects.

Phaeohyphomycotic soft tissue infections caused by the coelomycetous fungus Microsphaeropsis arundinis

Microsphaeropsis arundinis is an anamorphic fungal plant inhabitant belonging to the form class Coelomycetes. We describe two cases of M. arundinis soft tissue infections in immunosuppressed patients. This organism has not previously been described as causing disease in humans. It was identified on the basis of its typical ostiolate pycnidial conidiomata, ampulliform conidiogenous cells, and small, smooth-walled, brown, cylindrical conidia.

MRI for Diagnosis and Monitoring of Patients with Eosinophilic Fasciitis

OBJECTIVE

The objective of this study was to describe MRI findings in patients with eosinophilic fasciitis (EF) and to correlate clinical and laboratory findings with the MRI findings.

MATERIALS AND METHODS

Six patients with histologically proven EF underwent MRI at the time of diagnosis and after therapy (15 MRI examinations). Unenhanced T1-weighted, T2-weighted, and STIR sequences were performed using a 1.5-T MRI system. In addition, all patients were imaged with contrast-enhanced T1-weighted sequences. MRI findings, clinical findings, and laboratory parameters were retrospectively reviewed.

RESULTS

At the time the six patients presented, all eight MRI examinations revealed symmetric thickening and hyperintensity of the superficial muscle fasciae of the thigh, calves, or arms on unenhanced T1-weighted, T2-weighted, or STIR sequences, with strong enhancement after administration of IV contrast agent. In seven of the eight MRI examinations, similar signal changes were also present in the deep muscle fasciae. After treatment, the fascial abnormalities found on MRI disappeared on six of eight MRI examinations performed in five patients-a rate that correlated well with the clinical findings. In one patient with EF involvement of the thigh, the MRI abnormalities showed partial remission, which also correlated well with the clinical findings.

CONCLUSION

In EF, MRI reveals characteristic findings including thickening, signal abnormalities, and contrast enhancement of the superficial and, to a lesser extent, deep muscle fasciae. MRI is useful for establishing the diagnosis, guiding the choice of biopsy site, and assessing treatment response.

Imaging Findings in Musculoskeletal Complications of AIDS

Patients with human immunodeficiency virus (HIV) infection and acquired immunodeficiency syndrome (AIDS) are susceptible to a variety of complications that can affect the musculoskeletal system. These complications can be infectious, inflammatory, or neoplastic or can take some other form. Infection (cellulitis, necrotizing fasciitis, soft-tissue abscess, pyomyositis, osteomyelitis, septic arthritis) is the most common complication. Inflammatory processes include various arthritides as well as polymyositis. Non-Hodgkin lymphoma and Kaposi sarcoma are the two most common neoplasms in this patient population. Miscellaneous disorders include osteonecrosis, osteoporosis, rhabdomyolysis, anemia-related abnormal bone marrow, and hypertrophic osteoarthropathy. The underlying mechanisms leading to these diseases are complex and not fully understood but are thought to be multifactorial. Radiology may play an important role in early diagnosis and treatment planning in this population, in whom clinical and laboratory findings are commonly equivocal and nonspecific. Although biopsy is often necessary for the final diagnosis, it is important for the radiologist to be familiar with the different types of musculoskeletal disease in HIV-positive and AIDS patients so that an appropriate differential diagnosis can be established.

Diabetes alters the response to bacteria by enhancing fibroblast apoptosis

Diabetics suffer from both more frequent bacterial infections and greater consequences of infection. However, bacteria-induced tissue destruction and the subsequent response in diabetics have received relatively little attention. To investigate this issue, we inoculated the scalp of control or db/db diabetic mice, with the pathogen Porphyromonas gingivalis, which causes connective tissue destruction in humans. Both bacteria-induced cytokine expression and tissue loss were similar in diabetic and control mice. However, there was a significantly higher rate of fibroblast-specific apoptosis in the diabetic group, which was measured as cells that were double positive for the terminal deoxynucleotidyltransferase-mediated deoxy-UTP nick end labeling assay and expression of vimentin. The higher rate of fibroblast apoptosis could be explained in the diabetic group by enhanced levels of activated caspase-3. Apoptosis was evident during the peak healing period and coincided with reduced numbers of fibroblasts, diminished collagen I and III expression, and significantly reduced formation of new connective tissue matrix in diabetic mice. Thus, diabetes may impair the healing response to bacteria-induced connective tissue loss by increasing the number of caspase-3-activated fibroblasts, leading to greater apoptosis and reduced numbers of fibroblastic cells.

Soft-tissue abscess involving Actinomyces odontolyticus and two Prevotella species in an intravenous drug abuser

Skin and soft-tissue infections in intravenous users comprise a variety of microorganisms and anaerobic bacteria are frequently involved in these suppurative infections. A case of subcutaneous abscess into anterior femoral muscles involving Actinomyces odontolyticus and two Prevotella species (Prevotella buccae and Prevotella melaninogenica) in an intravenous drug abuser is presented. This combination of microorganisms has not previously been described in soft-tissue infections. The patient volunteering that he licked his hypodermic needle prior to cocaine injection supports that the implicating bacteria originated from the oral cavity. Eventually, the patient recovered and at a 6-month follow-up a gradual improvement of his subcutaneous infection was noticed.

Ultrasonography of musculoskeletal infections in children

Ultrasonography is an important modality for evaluation of musculoskeletal infections in children because it is rapid, nonionising and very sensitive for (infectious) fluid collections and joint effusions. Moreover, the images are not degraded by metallic or motion artefacts (as with CT and MRI) and finally, ultrasonography offers the possibility of fine-needle aspiration to confirm the infectious nature of a fluid collection without unnecessary contamination of adjacent anatomical compartments. Ultrasonography should be combined with radiography because both imaging techniques are complimentary. The purpose of this article is to emphasise the role of ultrasonography in the diagnosis of various diseases in childhood, including cellulitis, subcutaneous abscess, necrotizing fasciitis, pyomyositis, infectious bursitis and arthritis, osteomyelitis, foreign bodies and infectious lymphadenitis. Along with conventional radiography, ultrasonography is a very valuable modality for early diagnosis and follow-up of musculoskeletal infections in children.

[Necrotizing soft tissue infections: role of the localization for the antibiotic management]

Necrotizing soft tissue infections (NSTI) are infrequent but life-threatening, and require prompt empirical antibiotic therapy. Current nosologic classifications have limited value because the criteria used are imprecise and their bacteriological specificity is uncertain. The aim of this study was to describe the bacterial flora and its antibiotic sensitivity in a cohort of patients with NSTI, and to derive guidelines for the choice of antimicrobial chemotherapy. This prospective study involved 120 patients. Aerobic and anaerobic bacteriological samples were taken from infected soft tissues. The species distribution and susceptibility of the isolates to various antibiotic (ATB) combinations were analyzed. The data were analyzed according to the type (cellulitis versus myonecrosis) and anatomical location of NSTI (abdomen and perineum; uterine cervix; limbs). The chi-square test was used to analyze qualitative variables, and Student's t test was used for quantitative variables. A total of 232 samples yielded bacterial isolates (122 aerobic, 110 anaerobic). The species distribution of anaerobes did not differ according to the nature of the involved tissue or the anatomic location. Gram-negative aerobes were more frequently isolated from abdominal, perineal and limb sites than from the cervix (p<0.05), while gram-positive aerobes showed the reverse distribution (p<0.05). Metronidazole was more effective than clindamycin on cervical isolates (95% vs 88%, p=0.0093). Among the broad-spectrum antibiotics tested, imipenem/cilastatin and piperacillin/tazobactam were equally effective against the different groups of bacteria (94% vs 88%, p=0.14), and were clearly more active than the other antibiotics (p<0.05), whatever the site of isolation, the bacterial species, and the type of NSTI. The five antibiotics tested showed similar efficacy against cervical isolates. These results suggest that the choice of antibiotic therapy for NSTI should depend on the anatomical site of involvement rather than the nature of the infection. For abdominal, perineal and limb NSTI, we recommend first-line treatment with a betalactam-inhibitor combination (piperacillin/tazobactam or ticarcillin/clavulanate) plus an agent active on gram-negative species (aminoglycoside or fluoroquinolone). For cervical NSTI, we recommend penicillin G/metronidazole, or amoxicillin/clavulanic acid.

[Wound-adapter in the treatment of purulent wounds]

The method of closure of soft tissues purulent wounds with wound-adapter of original construction has been developed and used in clinical practice. This method provides complete reposition and adaptation of wound margins without suture eruption. Good results (primary closure) were achieved in 85.8% cases in the study group, and in 49.7% cases in the control group, satisfactory results (secondary closure partly) - in 14.2 and 50.3% cases, respectively. Hospital stay was reduced from 27.6 +/- 1.5 to 22.4 +/- 0.7 bed-days (p < 0,05).

[Use of multi-dimensional statistic analysis for integral evaluation of treatment quality in patients with suppurative-inflammatory diseases of maxillofacial region]

Possibilities of modern methods of maths statistics for comparative evaluation of efficacy of different methods of treatment of patients with suppurative-inflammatory diseases of maxillo-facial region were analyzed and an integral index of treatment efficacy was suggested. Application of the integral index of treatment efficacy showed that intravenous injection of sodium hypochlorite and autohemotherapy with oxidized blood led to the closest apposition of cluster center of these patients to the cluster center of healthy persons. It testifies to greater efficacy of such treatment of the disease in comparison to the other methods.

Persistent subcutaneous Scedosporium apiospermum infection

We report the case of a 52-year-old male heart transplant recipient with a persistent localized subcutaneous infection by Scedosporium apiospermum. This form differs from the most common mycetoma by the absence of granules. The patient showed multiple nodules on the right hand that were surgically removed. Concomitantly, he received oral itraconazole, but the infection persisted for two years, and several surgical interventions were necessary to eradicate the infection. Our case demonstrates that a medical approach alone may be not sufficient to cure this fungal infection.

Honey in the management of infections

BACKGROUND

Honey, a natural product of bees of the genera Apis and Meliponinae, has been recognized for medicinal properties since antiquity. Honey has demonstrated antimicrobial properties. These effects are variably ascribed to the pH, hydrogen peroxide content, osmotic effect, and as yet unidentified compounds putatively described as inhibines.

MATERIALS AND METHODS

This review will explore the use of honey in necrotizing soft tissue infections, postsurgical wound infections, wounds other than postsurgical infections, Helicobacter pylori of the stomach and duodenum, and burns. Throughout, the in vitro evidence that exists and the explanations that can be offered for the purported benefits of honey will be reviewed. Most of the reports are either uncontrolled case series or in vitro observations. As such, detailed critique of statistical methods will not be undertaken.

CONCLUSION

The purpose of this paper is not to debunk honey therapy as a myth, but to stimulate thought among surgeons interested in surgical infection and perhaps serve as the nidus for future research. The use of honey should be considered when more conventional therapies have failed.

Post-surgical zygomycotic necrotizing subcutaneous infection caused by Absidia corymbifera

Necrotizing infections of the skin and subcutaneous tissue are usually bacterial in origin. Rarely, fungi of the class Zygomycetes, which cause deep mycoses, may be responsible for acute necrotizing infections of these areas. Several local and systemic predisposing factors have been associated with such acute necrotizing infections. Surgical debridement and amphotericin B remain the mainstay of treatment. In this report we describe a patient with post-surgical necrotizing subcutaneous infection caused by Absidia corymbifera, 2 weeks following appendectomy. Successful management with surgical debridement, topical amphotericin B and oral potassium iodide is reported.

Functional-morphologic MR imaging with ultrasmall superparamagnetic particles of iron oxide in acute and chronic soft-tissue infection: study in rats

PURPOSE

To investigate the use of magnetic resonance (MR) imaging enhanced with ultrasmall superparamagnetic particles of iron oxide (USPIO) to identify acute, early chronic, and late chronic abscess formation in an experimental model of soft-tissue abscess.

MATERIALS AND METHODS

Experimental soft-tissue infection in 15 rats was imaged with an MR imaging unit on days 1 and 2 (acute), days 5 and 6 (early chronic), and days 8 and 9 (late chronic) after inoculation of the infectious agent. All animals were imaged without contrast enhancement and immediately and 24 hours after USPIO administration. MR and histopathologic findings were compared. The changes in relative signal intensity (SI) and in the extent and pattern of contrast enhancement (macrophage distribution) between the animal groups were analyzed. Statistical testing was performed with Kruskal-Wallis analysis of variance and the chi2 test.

RESULTS

At 24 hours after USPIO administration, the relative SI of the abscess wall and the relative macrophage extent were 0.50 (0.33-0.73) and 1.03 (0.90-1.08), respectively, for acute infection; 0.11 (0.10-0.18) and 0.94 (0.93-1.01) for early chronic infection; and 0.53 (0.44-0.58) and 0.80 (0.77-0.83) for late chronic infection. The changes in enhancement pattern (P <.001), relative SI (P <.001), and relative macrophage extent (P <.05) with time were significant.

CONCLUSION

The macrophage distribution pattern increases the specificity of MR findings in chronic infection and allows differentiation between areas with active inflammation and areas of reparative granulation tissue.

[Necrotizing soft tissue infections: nomenclature and classification]

Terminology used to refer to necrotizing infections is extensive because of the absence of clear definitions and the use of classification systems based on a variety of criteria, including etiologic, microbiologic, anatomic, and clinical aspects. This situation has led to some confusion. In the attempt to unify terminology, it might be more appropriate to use only the terms necrotizing fasciitis and myonecrosis, in which differentiation is mainly anatomical. Another option would be to use only the expression necrotizing soft tissue infections, a non-specific term, since these constitute a group of clinical processes having similar pathophysiologic characteristics and therapeutic principles.

[Primary giant hydatid cyst in the thigh]

Human hydatid cyst is a zoonotic infection that usually attacks visceral organs. Primary soft tissue involvement is very rare, causing a diagnostic challenge. Primary soft tissue hydatid cyst was encountered in an 83-year-old man, which presented as a giant lesion in the posterior aspect of the right thigh, extending from the gluteal region proximally to the popliteal region distally. A multiloculated cystic mass was completely resected and histopathological examination confirmed the preoperative diagnosis. No local or systemic complications occurred postoperatively. The patient recovered fully at the end of postoperative 12 months.

Necrotising infections of soft tissues--a clinical profile

OBJECTIVE

To study the clinical profile and outcome of patients with necrotising soft-tissue infections.

DESIGN

Prospective study.

SETTING

Teaching hospital, India.

SUBJECTS

75 patients (54 male and 21 female), mean age 40 years (range 8 months-85 years).

INTERVENTIONS

Patients were uniformly managed by initial resuscitation, debridement, topical wound care, systemic antibiotics, and enteral hyperalimentation.

MAIN OUTCOME MEASURES

Morbidity and mortality.

RESULTS

Aetiology of the infections included major and minor trauma, minor skin infections and postoperative infections. 22 patients were diabetic. The extremities were involved in 57 patients, the trunk in 26 and the perineum in 21. 68 presented with local tenderness (91%), 74 with oedema (99%), 54 with erythema (72%), 55 with ulceration (73%), and 54 with a purulent or serous discharge (72%). beta-haemolytic streptococci were isolated from only 10 patients. Staphylococcus aureus was the most common bacteria isolated (n = 30, 46%) followed by Bacteroides fragilis and anaerobic cocci (n = 22, 34% each). Cultures grew fungi in 9 patients. 20 patients died giving a mortality of 27%. Jaundice and serum albumin were the only factors to have a significant influence on mortality.

CONCLUSIONS

Necrotising soft tissue infections are potentially fatal. Early recognition and prompt aggressive debridement are the keys to successful management.

Necrotizing soft tissue infections of the head and neck: case reports and literature review

A small but nevertheless important part of a surgeon's experience comprises necrotizing soft tissue infections of the head and neck. The purpose of this report is to heighten awareness of necrotizing soft tissue infections in any patient with an infection of the head and neck. The article also outlines an appropriate management strategy for use in the treatment of patients with this potentially fatal condition. Prompt diagnosis and early radical surgical debridement are significant factors in avoiding a fatal outcome in these patients. This article reviews the literature on necrotizing soft tissue infections of the head and neck and presents cases from our recent experience.

A Case of Cervical Necrotizing Soft Tissue Infection

We treated a 62-year-old woman with a cervical necrotizing soft tissue infection of the Streptococcus milleri group. Numerous spot gas images were recognized from the right pharynx to the neck in CT at initial diagnosis, but we chose conservative treatment because abscess findings were not clear. The inflammation improved temporarily, but we operated through an outside incision because symptoms recurred and cervical skin became necrotic after one week. Inside, the fascia were necrotic and an abscess extended from the precordia to the left upper arm and the right axillary region. The cervical skin defect was restored in due course in about 2 months and cured without mediastinitis or sepsis developing. The S. milleri group was detected in pus. A cervical necrotizing soft tissue infection does not form an abscess mainly in one space as does a normal deep neck infection and invades fascia space rapidly and widely. We took this disease into consideration and had to intervene surgical rather soon. A review of this case and the literature indicates that the S. milleri group may have become an important pathogen in cervical necrotizing soft tissue infection.