Neural crest-derived mesenchymal progenitor cells enhance cranial allograft integration

Replacement of lost cranial bone (partly mesodermal and partly neural crest‐derived) is challenging and includes the use of nonviable allografts. To revitalize allografts, bone marrow‐derived mesenchymal stromal cells (mesoderm‐derived BM‐MSCs) have been used with limited success. We hypothesize that coating of allografts with induced neural crest cell‐mesenchymal progenitor cells (iNCC‐MPCs) improves implant‐to‐bone integration in mouse cranial defects. Human induced pluripotent stem cells were reprogramed from dermal fibroblasts, differentiated to iNCCs and then to iNCC‐MPCs. BM‐MSCs were used as reference. Cells were labeled with luciferase (Luc2) and characterized for MSC consensus markers expression, differentiation, and risk of cellular transformation. A calvarial defect was created in non‐obese diabetic/severe combined immunodeficiency (NOD/SCID) mice and allografts were implanted, with or without cell coating. Bioluminescence imaging (BLI), microcomputed tomography (μCT), histology, immunofluorescence, and biomechanical tests were performed. Characterization of iNCC‐MPC‐Luc2 vs BM‐MSC‐Luc2 showed no difference in MSC markers expression and differentiation in vitro. In vivo, BLI indicated survival of both cell types for at least 8 weeks. At week 8, μCT analysis showed enhanced structural parameters in the iNCC‐MPC‐Luc2 group and increased bone volume in the BM‐MSC‐Luc2 group compared to controls. Histology demonstrated improved integration of iNCC‐MPC‐Luc2 allografts compared to BM‐MSC‐Luc2 group and controls. Human osteocalcin and collagen type 1 were detected at the allograft‐host interphase in cell‐seeded groups. The iNCC‐MPC‐Luc2 group also demonstrated improved biomechanical properties compared to BM‐MSC‐Luc2 implants and cell‐free controls. Our results show an improved integration of iNCC‐MPC‐Luc2‐coated allografts compared to BM‐MSC‐Luc2 and controls, suggesting the use of iNCC‐MPCs as potential cell source for cranial bone repair.

Assessing the Resident Progenitor Cell Population and the Vascularity of the Adult Human Meniscus

PURPOSE

To identify, characterize, and compare the resident progenitor cell populations within the red-red, red-white, and white-white (WW) zones of freshly harvested human cadaver menisci and to characterize the vascularity of human menisci using immunofluorescence and 3-dimensional (3D) imaging.

METHODS

Fresh adult human menisci were harvested from healthy donors. Menisci were enzymatically digested, mononuclear cells isolated, and characterized using flow cytometry with antibodies against mesenchymal stem cell surface markers (CD105, CD90, CD44, and CD29). Cells were expanded in culture, characterized, and compared with bone marrow-derived mesenchymal stem cells. Trilineage differentiation potential of cultured cells was determined. Vasculature of menisci was mapped in 3D using a modified uDisco clearing and immunofluorescence against vascular markers CD31, lectin, and alpha smooth muscle actin.

RESULTS

There were no significant differences in the clonogenicity of isolated cells between the 3 zones. Flow cytometry showed presence of CD44⁺CD105⁺CD29⁺CD90⁺ cells in all 3 zones with high prevalence in the WW zone. Progenitors from all zones were found to be potent to differentiate to mesenchymal lineages. Larger vessels in the red-red zone of meniscus were observed spanning toward red-white, sprouting to smaller arterioles and venules. CD31⁺ cells were identified in all zones using the 3D imaging and co-localization of additional markers of vasculature (lectin and alpha smooth muscle actin) was observed.

CONCLUSIONS

The presence of resident mesenchymal progenitors was evident in all 3 meniscal zones of healthy adult donors without injury. In addition, our results demonstrate the presence of vascularization in the WW zone.

CLINICAL RELEVANCE

The existence of progenitors and presence of microvasculature in the WW zone of the meniscus suggests the potential for repair and biologic augmentation strategies in that zone of the meniscus in young healthy adults. Further research is necessary to fully define the functionality of the meniscal blood supply and its implications for repair.

Electrospun, synthetic bone void filler promotes human MSC function and BMP-2 mediated spinal fusion

INTRODUCTION

Synthetic bone grafts are often used to achieve a well-consolidated fusion mass in spinal fusion procedures. These bone grafts function as scaffolds, and ideally support cell function and facilitate protein binding.

OBJECTIVE

The aim was to characterize an electrospun, synthetic bone void filler (Reb) for its bone morphogenetic protein (BMP)-2 release properties and support of human mesenchymal stem cell (hMSC) function in vitro, and its efficacy in promoting BMP-2-/bone marrow aspirate-(BMA)-mediated posterolateral spinal fusion (PLF) in vivo.

METHODS

BMP-2 release kinetics from Reb versus standard absorbable collagen sponge (ACS) was determined. hMSC adhesion and proliferation on Reb was tested using cell counting, fluorescence microscopy and MTS. Cell osteogenic differentiation was quantified via cellular alkaline phosphatase (ALP) activity. For in vivo analysis, 18 Lewis rats were treated during PLF surgery with the following groups: (I) Reb + BMA, (II) Reb + BMA + BMP-2 and (III) BMA. A safe, minimally effective dose of BMP-2 was used. Fusion consolidation was followed for 3 months using radiography and micro-CT. After sacrifice, fusion rate and biomechanical stiffness was determined using manual palpation, biomechanical tests and histology.

RESULTS

In vitro, BMP-2 release kinetics were similar between Reb versus ACS. MSC proliferation and differentiation were increased in the presence of Reb. At 3 months post-surgery, fusion rates were 29% (group I), 100% (group II), and 0% (group III). Biomechanical stiffness was higher in group II versus I. Micro-CT showed an increased bone volume and connectivity density in group II. Trabecular thickness was increased in group I versus II. H&E staining showed newly formed bone in group II only.

CONCLUSIONS

Reb possesses a high protein binding affinity and promotes hMSC function. Combination with BMA and minimal dose BMP-2 allowed for 100% bone fusion in vivo. This data suggests that a minimally effective dose of BMP-2 can be used when combined with Reb.

The effect of insulin dependent diabetes on bone metabolism and growth after spinal fusion

STUDY DESIGN

Experimental animal model.

OBJECTIVE

The purpose of this study was to evaluate the hypothesis that insulin dependent diabetes mellitus (IDDM) will inhibit the formation of a solid bony union after spinal fusion surgery via an alteration of the microenvironment at the fusion site in a rat model.

SUMMARY OF BACKGROUND DATA

Previous studies report diabetes mellitus (DM) and specifically IDDM as a risk factor for complications and poor surgical outcomes following spinal fusion.

METHODS

Twenty control and 22 diabetic rats were obtained at 5 weeks of age. At 20 weeks of age, all animals underwent posterolateral lumbar fusion surgery using a tailbone autograft with diabetic rats receiving an implantable time release insulin pellet. A subset of rats was sacrificed 1-week postsurgery for growth factor (PDGF, IGF-I, TGF-β, and VEGF) and proinflammatory cytokine ELISA analysis. All other rats were sacrificed 3-months postsurgery for fusion evaluation via manual palpation and micro CT. Glycated hemoglobin (HbA1c) was measured at surgery and sacrifice on all animals.

RESULTS

Compared with healthy rats undergoing spinal fusion, rats with IDDM demonstrated a significant reduction in manual palpation fusion rates (16.7% vs. 43%, p<.05). Average bone mineral density, bone volume, and bone volume fraction were also significantly reduced and negatively correlated to blood glucose levels. IL-1B, IL-5, IL-10, TNF-α, and KC/GRO were significantly elevated in fusion beds of IDDM rats.

CONCLUSIONS

This study demonstrates that rats with IDDM demonstrate a reduced rate and quality of spinal fusion with increased local levels of inflammatory cytokines. Targeted modalities are required to improve bone healing in this growing, high-risk population.

CLINICAL SIGNIFICANCE

This is the first translational animal model of IDDM to evaluate the rate and quality of spinal fusion while controlling for other surgical and patient-related risk factors. Our findings demonstrate the complex nature by which IDDM impairs bone healing and highlight the need for additional basic science research to further elucidate this mechanism in order to develop more effective therapeutic interventions.

Omega-3 Fatty Acid Supplementation Reduces Intervertebral Disc Degeneration

Background

Intervertebral disc (IVD) degeneration is a common cause of lower back pain, which carries substantial morbidity and economic cost. Omega-3 fatty acids (n-3 FA) are known to reduce inflammatory processes with a relatively benign side effect profile. This study aimed to investigate the effect of n-3 FA supplementation on IVD degeneration.

Material/Methods

Two non-contiguous lumbar discs of 12 Sprague Dawley rats were needle-punctured to induce disc degeneration. Post-surgery, rats were randomly assigned to either a daily n-3 FA diet (530 mg/kg/day of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in a 2: 1 ratio, administered in sucrose solution) or control diet (sucrose solution only), which was given for the duration of the study. After 1 month, blood serum arachidonic acid/eicosapentaenoic acid (AA/EPA) ratios were analyzed. After 2 months, micro-MRI (magnetic resonance imaging) analysis and histological staining of disc explants were performed to analyze the IVD.

Results

A reduction of blood AA/EPA ratios from 40 to 20 was demonstrated after 1 month of daily supplementation with n-3 FA. Micro-MRI analysis showed an injury-induced reduction of IVD hydration, which was attenuated in rats receiving n-3 FA. Histological evaluation demonstrated the destruction of nucleus pulposus tissue in response to needle puncture injury, which was less severe in the n-3 FA diet group.

Conclusions

The results of this study suggest that n-3 FA dietary supplementation reduces systemic inflammation by lowering AA/EPA ratios in blood serum and has potential protective effects on the progression of spinal disc degeneration, as demonstrated by reduced needle injury-induced dehydration of intervertebral discs and reduced histological signs of IVD degeneration.

Association of Obesity with Increased Mortality in the Critically Ill Patient

The impact of obesity on critical care outcomes has been an issue for debate in the literature. Variable data and conflicting results have been reported. The purpose of our study is to examine the impact of obesity on the outcome of patients admitted to a tertiary closed Intensive Care Unit (ICU) in Saudi Arabia.

Data was obtained from a prospectively collected database from September 2001 to May 2004. Patients younger than 18, those with burns, brain death and readmissions were excluded. The study population was stratified into six groups according to their Body Mass Index (BMI). Primary endpoints were ICU and hospital mortality, duration of mechanical ventilation and ICU length of stay.

A total of 1835 patients were included in the analysis. Baseline characteristics were similar among the six groups including severity of illness scores, reflected by Acute Physiology and Chronic Health Evaluation II (APACHE II) scores. The ICU mortality was not statistically different among the groups. Hospital mortality was lower in patients with BMI 35–39.9 kg/m2 and BMI >40 kg/m2 compared to those with BMI 18.5–24.9 kg/m2. Multivariate analysis showed that a BMI >40 kg/m2 was an independent predictor of lower hospital mortality (odds ratio 0.51, 95% confidence interval 0.28–0.92, P 0.025) after adjustment for other confounding factors.

In conclusion, mortality of obese critically ill patients was not higher than patients with normal weight. In fact, the hospital mortality was lower for patients with BMI >40 kg/m2 compared to the normal BMI group despite similar severity of illness. Obesity might have a protective effect, although further studies are needed to substantiate this finding.

Importance of Adding Neomycin to Metronidazole for Bowel Preparation1

A prospective randomized trial has investigated whether it is necessary to add oral neomycin to oral metronidazole as a means of preventing sepsis in elective colonic resection. Seventy-three patients completed the study; 41 received metronidazole and placebo neomycin and 32 received metronidazole and active neomycin. There was a significant reduction in the incidence of wound infection in patients receiving neomycin and metronidazole (22%) compared with metronidazole alone (51%, P < 0.02). There was also a significant reduction in anaerobic infections in the group receiving metronidazole and neomycin compared with metronidazole alone (P < 0.05). These results indicate that oral metronidazole alone is of no benefit for patients requiring elective colonic operations and that if oral metronidazole is advised it should always be given in combination with oral neomycin.

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016

[This corrects the article DOI: 10.1186/s13054-016-1208-6.].

Outcome of tracheotomized patients following reintubation

OBJECTIVE

To evaluate the outcome of tracheotomized patients after reintubation.

METHOD

Secondary analysis from a prospective, multicenter and observational study including 36 Intensive Care Units (ICUs) from 8 countries.

PATIENTS

A total of 180 patients under mechanical ventilation for more than 48 hours, extubated and reintubated within 48 hours.

INTERVENTIONS

None.

OUTCOMES

ICU mortality, length of ICU stay, organ failure.

RESULTS

Fifty-two patients (29%) underwent tracheotomy after reintubation. The median time from reintubation to tracheotomy was 2.5 days (interquartile range (IQR) 1-8 days). The length of ICU stay was significantly longer in the tracheotomy group compared with the group without tracheotomy (median time 25 days, IQR 17-43 versus 16.5 days (IQR 11-25); p<0.001). ICU mortality in the tracheotomy group was not significantly different (31% versus 27%; p 0.57).

CONCLUSIONS

In our cohort of reintubated patients, tracheotomy is a common procedure in the ICU. Patients with tracheotomy had an outcome similar to those without tracheotomy.

Critical care medicine in Saudi Arabia

Critical care medicine remains underdeveloped in many parts of the world. In Saudi Arabia, there have been major developments in the past 2-3 decades. The purpose of this review is to give an account of the current status of critical care practice (including services provided during the haj season) and training in Saudi Arabia using examples of primary, secondary and tertiary care hospitals. The future needs of the profession are also addressed.

Effect of surfactant on pharyngeal mechanics in sleeping humans: implications for sleep apnoea

Instillation of surfactant into the pharyngeal lumen reduces the pressure required to reopen an occluded airway, and decreases the apnoea/hypopnoea index (AHI). The authors hypothesised that surfactant also reduces the sleep-related increase in pharyngeal resistance. To test this hypothesis two single blind, crossover, placebo-controlled studies were performed. In protocol A seven male, asymptomatic snoring subjects were studied during sleep. Inspiratory pharyngeal resistance was calculated from plots of airflow versus supraglottic pressure (seven breaths) before and after surfactant or saline instillation. In protocol B, in a different group of seven male subjects with sleep apnoea (AHI 15.2 (12) events x h(-1)) the effect of surfactant or saline on sleep disordered breathing was measured, for 1 h immediately before and after surfactant or saline instillation. Surfactant decreased pharyngeal resistance calculated at peak pressure (group mean (SD): pre versus post 83.7 (76.4) versus 49.4 (71.1) cmH2O x L(-1) x s(-1)) and significantly reduced the respiratory disturbance index (RDI pre versus post 79.7 (58.7) versus 59.6 (56.9) events x h(-1)). Saline did not decrease resistance (pre versus post 58.6 (31.1) versus 72.5 (73.4) cmH2O x L(-1) x s(-1)) or RDI (pre versus post 75.3 (42.4) versus 79.9 (46.1) events x h(-1)). Surfactant reduced the collapsibility of the pharynx and led to a modest reduction in respiratory disturbance index. The authors speculate that surfactant may delay occlusion by reducing the liquid "bridging" within the folded pharyngeal lining.

Daytime blood pressure elevation after nocturnal hypoxia

The purpose of this study was to investigate whether nocturnal hypoxia causes daytime blood pressure (BP) elevation. We hypothesized that overnight exposure to hypoxia leads the next morning to elevation in BP that outlasts the hypoxia stimulus. We studied the effect on BP of two consecutive night exposures to hypobaric hypoxia in 10 healthy normotensive subjects. During the hypoxia nights, subjects slept for 8 h in a hypobaric chamber at a simulated altitude of 4,000 m (barometric pressure = 462 mmHg). Arterial O(2) saturation and electrocardiogram were monitored throughout the night. For 30 min before the nocturnal simulated ascent and for 4 h after return to baseline altitude the next morning, BP was measured every 5 min while the subject was awake. The same measurements were made before and after 2 normoxic nights of sleep in the hypobaric chamber at ambient barometric pressure (745 mmHg). Principal components analysis was applied to evaluate patterns of BP response after the second night of hypoxia and normoxia. A distinct pattern of diastolic BP (DBP) elevation was observed after the hypoxia night in 9 of the 10 subjects but in none after the normoxia night. This pattern showed a mean increase of 4 mmHg in DBP compared with the presleep-awake baseline in the first 60 min and a return to baseline by 90 min. We conclude that nocturnal hypoxia leads to a carryover elevation of daytime DBP.

Progressive retropalatal narrowing preceding obstructive apnea

Pharyngeal occlusion during obstructive apnea is thought to be an inspiratory-related event; however, occlusion also occurs in the absence of negative intrathoracic pressure. We hypothesized that inspiratory-related pharyngeal occlusion would be preceded by significant expiratory narrowing. Eight sleeping patients with obstructive apnea were studied. Pharyngeal caliber, airflow, and esophageal pressure (Pes) were simultaneously monitored during three to four consecutive breaths preceding occlusion (between 3 and 22 events were studied per subject). Relative changes in retropalatal airway cross-sectional area (CSA) were determined from fiberoptic images (five frames per second) normalized to the maximum CSA. During inspiration, CSA was significantly reduced only during the breath immediately preceding the apnea (Group mean CSA +/- SEM: 51 +/- 8% at the start of inspiration compared with 37 +/- 8% at midinspiration). During expiration, for all breaths there was an initial significant increase in CSA compared with the nadir CSA during the preceding inspiration (CSA: breath-3, 57 +/- 10% to 79 +/- 3%; breath-2, 59 +/- 8% to 76 +/- 4%; breath-1, 37 +/- 8% to 64 +/- 8%), followed by a significant narrowing at end-expiration compared with the peak CSA during that expiration (CSA: breath-3, 79 +/- 3% to 62 +/- 6%; breath-2, 76 +/- 4% to 50 +/- 10%; breath-1, 64 +/- 8% to 36 +/- 10%). Occlusion occurred at a pressure significantly less than that generated during the previous unoccluded breath (Pes: breath-1, -10.8 +/- 2.9 cm H2O; occlusion, -8.2 +/- 1.9 cm H2O). These results show that expiratory narrowing produced a significant reduction of CSA at end-expiration prior to obstructive apnea.

Adrenal insufficiency, recurrent bacteremia, and disseminated abscesses caused by Nocardia asteroides in a patient with acquired immunodeficiency syndrome

Nocardia asteroides is an opportunistic pathogen of increasing incidence in human immunodeficiency virus (HIV)-infected persons. The lungs are the most common site of infection, followed by the brain; involvement of other extrapulmonary sites is less common. We describe a patient with acquired immunodeficiency syndrome who presented with a number of unique manifestations of nocardial infection: the first reported case of bilateral adrenal abscesses with adrenal insufficiency, the first case of a renal abscess due to N. asteroides alone, and the first case of recurrent, symptomatic bacteremia. A review of the literature on nocardial infections in HIV-positive individuals is presented.

Influence of oral mannitol bowel preparation on colonic microflora and the risk of explosion during endoscopic diathermy

Oral mannitol has been widely accepted as the bowel preparation of choice for colonoscopy and elective colorectal operation because it is well tolerated by patients. Recent concern has been expressed regarding the risk of explosion and sepsis using oral mannitol because it may provide a nutrient for certain gas-producing bacteria in the colon. Samples of colonic contents aspirated at operation were compared in patients prepared by oral mannitol, by whole bowel irrigation, mannitol preceded by 48 h of oral antibiotics (neomycin with metronidazole) and in patients who did not undergo any preparation. Significantly higher counts of gas-producing Escherichia coli were recovered from patients prepared with mannitol alone compared with whole bowel irrigation or mannitol preceded by oral antimicrobials. These data are consistent with the hypothesis that fermentation of mannitol by Escherichia coli is responsible for the production of potentially explosive gas mixtures after oral mannitol preparation and may also explain the increased incidence of sepsis when oral mannitol is used for bowel preparation.

Faecal toxin and severity of antibiotic-associated pseudomembranous colitis

The relationship between faecal toxin titre, histological evidence of pseudomembrane in the rectum, and severity of antibiotic-associated colitis has been analysed from data on 62 patients whose faeces contained Clostridium difficile toxin. There was a significant correlation between a toxin titre of 6400 or more and the presence of pseudomembrane (p less than 005). There was no correlation between toxin titre, duration of diarrhoea, total white cell count, temperature, serum albumin or serum orosomucoid concentrations. There was, however, a significant correlation between the presence of rectal pseudomembrane and duration of diarrhoea (p less than 0.005). Exposure to clindamycin or lincomycin was also associated with a significantly higher toxin titre than that seen in patients who were given other antibiotics. The duration of diarrhoea of diarrhoea was not longer and rectal pseudomembrane did not occur more often in the patients who had received clindamycin or lincomycin.

Sepsis following operation for inflammatory intestinal disease

The incidence and pathogenesis of sepsis following 107 elective operations in 87 patients with inflammatory bowel disease has been studied. Eighteen per cent developed wound sepsis and 13 per cent developed intra-abdominal abscess postoperatively. The prophylactic antimicrobial regimens used did not reduce the overall postoperative sepsis rates. The risk of developing postoperative sepsis was increased in patients with preoperative enterocutaneous or entero-enteric fistulas, pre-existing abscess and those with evidence of active disease (serum albumin less than 3.0 g/dl and serum seromucoids greater than 400 mg/gl). The incidence of postoperative sepsis was not affected by corticosteroid therapy at the time of surgery.

Modification of the physiological disturbances produced by whole gut irrigation by preliminary mannitol administration

In a prospective non-randomized study of 42 patients it was found that the oral administration of 50 g of mannitol 2 h before whole bowel irrigation (WBI) improved the success rate of the bowel preparation and reduced the time required for the WBI. Mannitol is an osmotic cathartic, and it reduced fluid absorption from a mean value of 2.7 l in patients who had WBI alone to a mean of 1.2 l in those who received mannitol beforehand. Sodium absorption was also significantly reduced.

Clinical and manometric evaluation of rectal prolapse and incontinence

The clinical presentation and manometric findings in 46 patients with rectal prolapse and/or incontinence are reported. Basal and maximal squeeze pressures in the anal canal of patients with prolapse alone did not differ from the pressures in age and sex-matched controls whereas anal pressures in both groups of patients with incontinence were significantly lower than in controls. Physiotherapy and faradism had no therapeutic value in rectal prolapse but gave improvement in 30 per cent of patients with incontinence. Rectopexy gave satisfactory results in all the patients with prolapse and improved incontinence in 70 per cent. Post-anal repair cured 87 per cent of patients with idiopathic anorectal incontinence or with persistent incontinence after rectopexy. No form of treatment was associated with any significant elevation of anal pressures.

Prospective trials of minor surgical procedures and high-fibre diet for haemorrhoids

Two hundred and sixteen consecutive patients seen for the first time with symptomatic haemorrhoids entered trials of conservative and minor surgical treatment. They were divided into two groups according to their pretreatment maximal anal pressure. Patients with pressures of 100 cm H2O (73.7 mm Hg) or more (108 patients) were treated by anal dilatation (37), sphincterotomy (34), or high-fibre diet (37). Four and 12 months later anal dilatation had produced significantly better results than sphincterotomy or diet. Furthermore, anal dilatation was the only treatment associated with a significant reduction in anal pressure at four and 12 months. Patients with pressures under 100 cm H2O (108 patients) were treated by rubber-band ligation (35), cryosurgery (36), or diet (37). Four and 12 months later significantly more patients were improved by rubber-band ligation than by cryosurgery or diet. These results suggest that haemorrhoids in patients with excessive activity of the internal anal sphincter are best treated by anal dilatation and that in all other patients rubber-band ligation is the treatment of choice.

Influence of neomycin and metronidazole on colonic microflora of volunteers

The influence on colonic microflora of neomycin and metronidazole alone, or in combination, was studied in volunteers taking a normal diet. Bacterial counts on daily faecal samples revealed that metronidazole had no influence on anaerobic faecal bacteria. Neomycin on the other hand, was effective against sensitive aerobes. However, the combination of neomycin and metronidazole profoundly reduced both aerobic and bacteria. Assay of faecal antibiotic concentrations showed that neomycin achieved high intraluminal levels while metronidazole was undetectable or present at low concentrations.

A randomized controlled trial to compare anal dilatation with lateral subcutaneous sphincterotomy for anal fissure

A prospective randomized trial has compared manual dilatation of the anus (MDA)during general anesthesia with lateral subcutaneous spincterotomy (LSS) during local anesthesia for the management of anal fissure in 156 patients. The two groups were similar with respect to age, sex and symptoms. There was no difference in the duration of time off work or early complications of treatment but, four months after operation, 93 per cent claimed to have been improved by MDA compared with 78 per cent after LSS (P less than 0.05). Recurrent fissure was recorded in 13 patients after LSS (29 per cent) compared with four (10 per cent) after MDA (P less than 0.02). There was a significant reduction in anal pressure at four months (P less than 0.02) after MDA, (123 +/- 31 to 97 +/-33) and LSS (127 +/- 36 to 104 +/- 32), but the anal pressure remained unchanged by operation in all patients where pressures were measured with recurrent fissure. These data indicate that MDA gives better results than LSS for treatment of anal fissure and that successful treatment is associated with a reduction in anal pressure.

Comparison between systemic and oral antimicrobial prophylaxis in colorectal surgery

In a prospective randomised trial in which 93 patients undergoing elective colorectal operations were given a short prophylactic course of metronidazole and kanamycin orally or systemically, postoperative sepsis occurred in only 3 (6.5%) of those given antimicrobials systemically, compared with 17 (36%) of those given oral prophylaxis (P less than 0.01). 15 of the 17 infections in patients who received antimicrobials orally were due to kanamycin-resistant bacteria present in the colon at operation. Bacterial overgrowth of Staphylococcus aureus was recorded in 6 of the patients who received oral therapy. Antibiotic-associated pseudomembranous colitis occurred in 7 patients, 6 of whom had received prophylaxis orally. These results indicate that oral administration of prophylactic antimicrobials in colon surgery should be avoided because of the risks of bacterial resistance, superinfection, and antibiotic-associated pseudomembranous colitis. Systemic per-operative antimicrobial prophylaxis is safer and more effective.

Randomised controlled trial of vancomycin for pseudomembranous colitis and postoperative diarrhoea

The efficacy of vancomycin in pseudomembranous colitis was assessed in a prospective randomised controlled trial. Forty-four patients with postoperative diarrhoea were allocated to five days' treatment with either 125 mg vancomycin six-hourly or a placebo. Sixteen patients had high titres of the neutralised faecal toxin characteristic of pseudomembranous colitis; nine received vancomycin and seven placebo. At the end of treatment faecal toxins were present in one patient given vancomycin compared with five of the controls. Vancomycin caused the disappearance of Clostridum difficile from the stool in all except one patient, whereas toxicogenic strains of Cl difficile persisted in all but one of the controls. Histological evidence of psuedomembranous colitis had disappeared by the end of treatment in six out of seven patients given vancomycin compared with only one out of seven patients given vancomycin compared with only one out of five patients given placebo. In patients with faecal toxins bowel habit had returned to normal in seven of the vancomycin group compared with only one of the controls, but there was no significant difference in clinical response among patients without faecaal toxins. The results suggest that vancomycin eliminates toxin-producing Cl difficile from the colon and is associated with rapid clinical and histological improvement in patients with pseudomembranous colitis.

Diarrhoea and pseudomembranous colitis after gastrointestinal operations. A prospective study

241 patients who had gastrointestinal operations were studied prospectively. Postoperative diarrhoea occurred in 58 patients (24%) and was significantly more common after exposure to antibiotics. 9 patients (4%) had high titres of a neutralisable faecal toxin characteristic of pseudomembranous colitis. Toxigenic Clostridium difficile strains were isolated from the stools of all patients with neutralisable faecal toxin. If pseudomembranous colitis is defined as the presence of neutralisable faecal toxin, then the diagnosis is often missed by sigmoidoscopy and rectal biopsy.

Influence of inflammatory bowel disease on intestinal microflora

The microflora of the jejunum, ileum, and colon has been studied from operative samples in Crohn's disease (n = 30), ulcerative colitis (n = 15), and controls (n = 40). There was no significant difference in the flora of patients with ulcerative colitis compared with controls. In Crohn's disease there was a significant increase in E. coli (P less than 0.001) and B. fragilis (P less than 0.001) in the ileum and of E. coli (P less than 0.001) and lactobacilli (P less than 0.01) in the colon. The abnormal ileal flora in Crohn's disease was unrelated to serological evidence of disease activity (indices: ESR, serum albumin, serum seromucoids), diameter of the ileum, or excision of the ileocaecal valve. The abnormal colonic flora in Crohn's disease was not related to presence of macroscopic colitis.