Comparison of therapeutic antibiotic treatments on tissue-engineered human skin substitutes

For regenerative medicine to gain clinical acceptance, the effects of commonly used treatment regimens on bioengineered organs must be considered. The antibiotics mafenide acetate (mafenide) and neomycin plus polymyxin (neo/poly) are routinely used to irrigate postoperative skin grafts on contaminated wounds. The effects of these clinically used antibiotics were investigated using tissue-engineered human skin substitutes generated with primary human keratinocytes or the near-diploid human keratinocyte cell line, Near-diploid Immortal Keratinocytes. Following topical or dermal treatment, the skin substitutes were assayed for viability, tissue morphology, glycogen content, and the expression of active caspase 3. Mafenide, but not neo/poly, induced morphological and biochemical changes in tissue-engineered skin substitutes. Keratinocytes in all histological layers of mafenide-treated skin substitutes exhibited ballooning degeneration and glycogen depletion. Mafenide-treatment also triggered separation of basal keratinocytes from the underlying dermis. None of the antibiotic treatments induced apoptosis, as measured by active caspase 3 immunostaining. The results demonstrate that mafenide, but not neo/poly, is detrimental to the viability and structural integrity of tissue-engineered human skin substitutes. These findings highlight the need to identify treatment regimens that are compatible with and hence enable the therapeutic efficacy of first-generation bioengineered organs such as skin.

Skim milk enhances the preservation of thawed -80 degrees C bacterial stocks

The results from bacterial strain recovery efforts following hurricanes Katrina and Rita are reported. Over 90% of strains frozen in 10% skim milk were recovered whereas various recovery rates were observed for glycerol-stored stocks (56% and 94% of Escherichia coli, depending upon the laboratory). These observations led to a viability comparison of Streptococcus pyogenes, Campylobacter jejuni, Borrelia burgdorferi, Salmonella enterica subsp. Typhimurium, Pseudomonas aeruginosa and E. coli strains stored in glycerol or skim milk. In all bacteria examined, 10% skim milk resulted in significantly longer viability after thawing than 15% glycerol solutions currently used in most laboratories.

Phenotyping Clostridium septicum infection: a surgeon's infectious disease

BACKGROUND

Clostridium septicum infection is associated with malignancy. Whether disease phenotype is affected by malignant status is not known. Surgical treatment is used frequently but its impact on survival has not been examined in a cohort >30 patients.

METHODS

A PubMed search of English language journal articles yielded 320 cases. Full information (infection location, cancer type, operative intervention, and survival) was available for 224 cases + 7 at our institution not previously reported.

RESULTS

Seventy-two percent of patients had malignancy or malady of the gastrointestinal (GI) or hematologic (HEME) organ systems. HEME survival was inferior to GI survival (35% versus 55%, P = 0.03). Overall, patients who underwent operation had improved survival (57% versus 26%; P < 0.0001) and this association was maintained within GI and HEME cohorts (P = 0.002 and 0.005, respectively). More GI than HEME patients underwent operation (81% versus 51%, P < 0.001). GI patients were more likely than HEME patients to experience infection of skin and soft tissues (SSTI, P = 0.006). Diabetics were more likely to experience SSTI than nondiabetics (77% versus 45%, P < 0.001).

CONCLUSIONS

C. septicum infectious phenotype varies with host milieu. The SSTI phenotype is more common in GI and diabetic patients. This recognition may aid in directing the search for occult malignancy, which must be performed given the >70% incidence of concomitant cancer. This infection is more fatal in HEME versus GI patients, perhaps due in part to less HEME group operative intervention. Primary surgical therapy should be considered in GI or HEME patients as operative intervention benefits both groups.

Pseudomonas aeruginosa AlgR represses the Rhl quorum-sensing system in a biofilm-specific manner

AlgR controls numerous virulence factors in Pseudomonas aeruginosa, including alginate, hydrogen cyanide production, and type IV pilus-mediated twitching motility. In this study, the role of AlgR in biofilms was examined in continuous-flow and static biofilm assays. Strain PSL317 (DeltaalgR) produced one-third the biofilm biomass of wild-type strain PAO1. Complementation with algR, but not fimTU-pilVWXY1Y2E, restored PSL317 to the wild-type biofilm phenotype. Comparisons of the transcriptional profiles of biofilm-grown PAO1 and PSL317 revealed that a number of quorum-sensing genes were upregulated in the algR deletion strain. Measurement of rhlA::lacZ and rhlI::lacZ promoter fusions confirmed the transcriptional profiling data when PSL317 was grown as a biofilm, but not planktonically. Increased amounts of rhamnolipids and N-butyryl homoserine lactone were detected in the biofilm effluent but not the planktonic supernatants of the algR mutant. Additionally, AlgR specifically bound to the rhlA and rhlI promoters in mobility shift assays. Moreover, PAO1 containing a chromosomal mutated AlgR binding site in its rhlI promoter formed biofilms and produced increased amounts of rhamnolipids similarly to the algR deletion strain. These observations indicate that AlgR specifically represses the Rhl quorum-sensing system during biofilm growth and that such repression is necessary for normal biofilm development. These data also suggest that AlgR may control transcription in a contact-dependent or biofilm-specific manner.

Two-pronged survival strategy for the major cystic fibrosis pathogen, Pseudomonas aeruginosa, lacking the capacity to degrade nitric oxide during anaerobic respiration

Protection from NO gas, a toxic byproduct of anaerobic respiration in Pseudomonas aeruginosa, is mediated by nitric oxide (NO) reductase (NOR), the norCB gene product. Nevertheless, a norCB mutant that accumulated approximately 13.6 microM NO paradoxically survived anaerobic growth. Transcription of genes encoding nitrate and nitrite reductases, the enzymes responsible for NO production, was reduced >50- and 2.5-fold in the norCB mutant. This was due, in part, to a predicted compromise of the [4Fe-4S](2+) cluster in the anaerobic regulator ANR by physiological NO levels, resulting in an inability to bind to its cognate promoter DNA sequences. Remarkably, two O(2)-dependent dioxygenases, homogentisate-1,2-dioxygenase (HmgA) and 4-hydroxyphenylpyruvate dioxygenase (Hpd), were derepressed in the norCB mutant. Electron paramagnetic resonance studies showed that HmgA and Hpd bound NO avidly, and helped protect the norCB mutant in anaerobic biofilms. These data suggest that protection of a P. aeruginosa norCB mutant against anaerobic NO toxicity occurs by both control of NO supply and reassignment of metabolic enzymes to the task of NO sequestration.

National Burn Repository 2005: a ten-year review

In the early 1990s, the American Burn Association (ABA) started its first burn registry development initiatives. The impetus for the registry development software originated from several directions, including the following: (1) the recognition that national registries were widespread and of proven benefit; (2) growing demands from accrediting institutions, payers, and patient advocacy groups for objective and verifiable data regarding patient costs, treatments, and outcomes; and (3) the shift toward "evidence-based" medicine and the ongoing analysis of treatment effectiveness. The ABA has issued three calls for burn registry data for its National Burn Repository (NBR): 1994, 2002, and 2005. In 1994, 28 burn centers contributed data for more than 6,400 patients treated from 1991 to 1993. The ABA announced its second call for data in 2001 and distributed the published results of more than 54,000 acute burn admissions treated from 1974 to 2002 at the Association's 2002 Annual Meeting. The third ABA call for data was issued in the Fall of 2005. The results are detailed in this report, which provides a summary of more than a quarter million acute burn admissions from 1995 to 2005, representing 70 hospitals from 30 states plus the District of Columbia. Statistics are presented in chart and table format to illustrate such key factors as patient age, burn size group, types of injuries, mortality rates, and average hospital charges by etiology and length of hospital stay. The data presented herein should help stimulate quality improvement programs in burn care, as burn centers compare their performance with the national data and as research is expanded using the NBR. The NBR will be published annually and, with continued refinements to the registry software, should become of increasing importance to clinicians, payers, researchers, and the public.

Clinical experience with Alloderm: A one-staged composite dermal/epidermal replacement utilizing processed cadaver dermis and thin autografts

Alloderm has been advocated for the management of acute burns. However, few studies have demonstrated the feasibility of this technique.

METHODS

We reviewed the medical records of all patients treated in our burn center who received Alloderm since 1999.

RESULTS

Alloderm was used in 21 burn patients and 6 patients with traumatic skin loss. The average size of Alloderm used in the burn patients was 517+/-144 cm(2) (range 24-3000 cm(2)). The average Alloderm thickness used was 0.008 in. and autografts were harvested at an average of 0.007 in. Overall, Alloderm was used in a variety of locations including the face in 3 patients (2 burns, 1 traumatic skin loss) and hands in 7 patients (6 burns, 1 traumatic skin loss). Successful take was observed in 26/27 patients.

CONCLUSIONS

Alloderm can be used successfully in patients with acute burns requiring grafting.

Anaerobic killing of mucoid Pseudomonas aeruginosa by acidified nitrite derivatives under cystic fibrosis airway conditions

Mucoid, mucA mutant Pseudomonas aeruginosa cause chronic lung infections in cystic fibrosis (CF) patients and are refractory to phagocytosis and antibiotics. Here we show that mucoid bacteria perish during anaerobic exposure to 15 mM nitrite (NO2) at pH 6.5, which mimics CF airway mucus. Killing required a pH lower than 7, implicating formation of nitrous acid (HNO2) and NO, that adds NO equivalents to cellular molecules. Eighty-seven percent of CF isolates possessed mucA mutations and were killed by HNO2 (3-log reduction in 4 days). Furthermore, antibiotic-resistant strains determined were also equally sensitive to HNO2. More importantly, HNO2 killed mucoid bacteria (a) in anaerobic biofilms; (b) in vitro in ultrasupernatants of airway secretions derived from explanted CF patient lungs; and (c) in mouse lungs in vivo in a pH-dependent fashion, with no organisms remaining after daily exposure to HNO2 for 16 days. HNO2 at these levels of acidity and NO2 also had no adverse effects on cultured human airway epithelia in vitro. In summary, selective killing by HNO2 may provide novel insights into the important clinical goal of eradicating mucoid P. aeruginosa from the CF airways.

A549 lung epithelial cells grown as three-dimensional aggregates: alternative tissue culture model for Pseudomonas aeruginosa pathogenesis

A three-dimensional (3-D) lung aggregate model was developed from A549 human lung epithelial cells by using a rotating-wall vessel bioreactor to study the interactions between Pseudomonas aeruginosa and lung epithelial cells. The suitability of the 3-D aggregates as an infection model was examined by immunohistochemistry, adherence and invasion assays, scanning electron microscopy, and cytokine and mucoglycoprotein production. Immunohistochemical characterization of the 3-D A549 aggregates showed increased expression of epithelial cell-specific markers and decreased expression of cancer-specific markers compared to their monolayer counterparts. Immunohistochemistry of junctional markers on A549 3-D cells revealed that these cells formed tight junctions and polarity, in contrast to the cells grown as monolayers. Additionally, the 3-D aggregates stained positively for the production of mucoglycoprotein while the monolayers showed no indication of staining. Moreover, mucin-specific antibodies to MUC1 and MUC5A bound with greater affinity to 3-D aggregates than to the monolayers. P. aeruginosa attached to and penetrated A549 monolayers significantly more than the same cells grown as 3-D aggregates. Scanning electron microscopy of A549 cells grown as monolayers and 3-D aggregates infected with P. aeruginosa showed that monolayers detached from the surface of the culture plate postinfection, in contrast to the 3-D aggregates, which remained attached to the microcarrier beads. In response to infection, proinflammatory cytokine levels were elevated for the 3-D A549 aggregates compared to monolayer controls. These findings suggest that A549 lung cells grown as 3-D aggregates may represent a more physiologically relevant model to examine the interactions between P. aeruginosa and the lung epithelium during infection.

The transcriptional regulator AlgR controls cyanide production in Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic pathogen that causes chronic lung infections in cystic fibrosis (CF) patients. One characteristic of P. aeruginosa CF isolates is the overproduction of the exopolysaccharide alginate, controlled by AlgR. Transcriptional profiling analyses comparing mucoid P. aeruginosa strains to their isogenic algR deletion strains showed that the transcription of cyanide-synthesizing genes (hcnAB) was approximately 3-fold lower in the algR mutants. S1 nuclease protection assays corroborated these findings, indicating that AlgR activates hcnA transcription in mucoid P. aeruginosa. Quantification of hydrogen cyanide (HCN) production from laboratory isolates revealed that mucoid laboratory strains made sevenfold more HCN than their nonmucoid parental strains. In addition, comparison of laboratory and clinically derived nonmucoid strains revealed that HCN was fivefold higher in the nonmucoid CF isolates. Moreover, the average amount of cyanide produced by mucoid clinical isolates was 4.7 +/- 0.85 micromol of HCN/mg of protein versus 2.4 +/- 0.40 micromol of HCN/mg of protein for nonmucoid strains from a survey conducted with 41 P. aeruginosa CF isolates from 24 patients. Our data indicate that (i) mucoid P. aeruginosa regardless of their origin (laboratory or clinically derived) produce more cyanide than their nonmucoid counterparts, (ii) AlgR regulates HCN production in P. aeruginosa, and (iii) P. aeruginosa CF isolates are more hypercyanogenic than nonmucoid laboratory strains. Taken together, cyanide production may be a relevant virulence factor in CF lung disease, the production of which is regulated, in part, by AlgR.

Continuous local anesthetic infusion for pain management after outpatient inguinal herniorrhaphy

BACKGROUND

The purpose of the present study is to compare postoperative pain and functional outcomes in patients undergoing inguinal herniorrhaphy who receive a continuous wound infusion of bupivacaine to those who receive an infusion of saline.

METHODS

A prospective, randomized, blinded, placebo-controlled trial was conducted in adults undergoing outpatient inguinal herniorrhaphy. Patients received saline or bupivacaine through a disposable infusion pump for 60 hours postoperatively. Pain outcomes were assessed, as were functional outcomes (activity, return of bowel function) and side effects.

RESULTS

On postoperative day 1, patients who received bupivacaine had lower ratings for worst pain than patients who received saline, (5.0 +/- 2.3 vs 6.7 +/- 2.2, P=.002). On day 1, least pain ratings were also lower, and patients ambulated more frequently than those who received placebo. There were no differences between groups from postoperative days 2 to 5. There were no differences between groups in the amount of hydrocodone consumption.

CONCLUSIONS

Continuous infusion of local anesthetic after inguinal herniorrhaphy provides modest improvements in pain scores and functional outcomes when compared with placebo. However, these effects are limited to the first postoperative day only. The additional costs associated with this intervention may limit its widespread use in clinical practice.

Transcriptome analysis of Pseudomonas aeruginosa after interaction with human airway epithelial cells

The transcriptional profile of Pseudomonas aeruginosa after interactions with primary normal human airway epithelial cells was determined using Affymetrix GeneChip technology. Gene expression profiles indicated that various genes involved in phosphate acquisition and iron scavenging were differentially regulated.

Identification of AlgR-regulated genes in Pseudomonas aeruginosa by use of microarray analysis

The Pseudomonas aeruginosa transcriptional regulator AlgR controls a variety of different processes, including alginate production, type IV pilus function, and virulence, indicating that AlgR plays a pivotal role in the regulation of gene expression. In order to characterize the AlgR regulon, Pseudomonas Affymetrix GeneChips were used to generate the transcriptional profiles of (i) P. aeruginosa PAO1 versus its algR mutant in mid-logarithmic phase, (ii) P. aeruginosa PAO1 versus its algR mutant in stationary growth phase, and (iii) PAO1 versus PAO1 harboring an algR overexpression plasmid. Expression analysis revealed that, during mid-logarithmic growth, AlgR activated the expression of 58 genes while it repressed the expression of 37 others, while during stationary phase, it activated expression of 45 genes and repression of 14 genes. Confirmatory experiments were performed on two genes found to be AlgR repressed (hcnA and PA1557) and one AlgR-activated operon (fimU-pilVWXY1Y2). An S1 nuclease protection assay demonstrated that AlgR repressed both known hcnA promoters in PAO1. Additionally, direct measurement of hydrogen cyanide (HCN) production showed that P. aeruginosa PAO1 produced threefold-less HCN than did its algR deletion strain. AlgR also repressed transcription of two promoters of the uncharacterized open reading frame PA1557. Further, the twitching motility defect of an algR mutant was complemented by the fimTU-pilVWXY1Y2E operon, thus identifying the AlgR-controlled genes responsible for this defect in an algR mutant. This study identified four new roles for AlgR: (i) AlgR can repress gene transcription, (ii) AlgR activates the fimTU-pilVWXY1Y2E operon, (iii) AlgR regulates HCN production, and (iv) AlgR controls transcription of the putative cbb3-type cytochrome PA1557.

Complex Regional Pain Syndrome as a Complication of a Chemical Burn to the Foot

Complex regional pain syndrome (CRPS) is an unusual complication after burns; however, it is important to recognize so that appropriate treatment can be administered. A 60-year-old man suffered an alkali burn to the right foot. Subsequently, the patient developed CRPS with severe pain and vasomotor changes. Multimodal treatment included the early use of ropivacaine and fentanyl via epidural catheter. Oral extended-release morphine, gabapentin, and amitriptyline also were administered. Once pain was controlled, early aggressive physical therapy was instituted, and attention was turned toward wound coverage. One year after discharge, the patient was ambulating well and has returned to work. His pain was managed with a single morning dose of gabapentin and a nonsteroidal anti-inflammatory agent. Current examination of the foot revealed mild forefoot swelling without residual erythema. Ambiguities exist in the mainstay of treatment for CRPS, but this multimodal method of controlling CRPS after burn injury allowed for control of the patient's pain, early mobilization, and eventual return to work.

Quantifying Pseudomonas aeruginosa adhesion to contact lenses

PURPOSE

Pseudomonal keratitis can occur in soft contact lens wearers following compromise of the corneal epithelium and exposure to pathogens. This study was initiated to determine if Pseudomonas aeruginosa has the ability to adhere preferentially to unused contact lenses made from different FDA group polymers.

METHODS

Pseudomonas aeruginosa (strain PA01) was grown to its early stationary phase and diluted into phosphate-buffered saline to a concentration of 12000 to 16000 cells/mL. Samples from each of the four FDA-designated polymer classes used for the manufacture of soft lenses were incubated in pseudomonal inoculant for 4 hours. The lenses were removed and the number of bacteria bound was quantified using electrical impedance particle counting.

RESULTS

A lens constructed from a group I polymer (nonionic polymer with <50% water) bound the fewest bacteria (7.2% of total cells +/- 1.0 SD) whereas a lens made from group II polymers (nonionic polymer with >50% water) showed the highest level of bacterial binding (42% of total cells +/- 4.5 SD). Lenses constructed from group III and IV polymers showed intermediate levels of bacterial binding (28.4% +/- 1.8 SD and 29.3% +/- 1.7 SD, respectively).

CONCLUSIONS

The polymer type used to construct the contact lens may influence subsequent bacterial adhesion events. Contact lenses made from nonionic polymers with high water content may carry higher risks of bacterial contamination.

The transcriptional regulator AlgR is essential for Pseudomonas aeruginosa pathogenesis

Chronic Pseudomonas aeruginosa lung infection is the major cause of morbidity and mortality in cystic fibrosis (CF) patients. One P. aeruginosa virulence factor unique to CF isolates is overproduction of alginate, phenotypically termed mucoidy. Mucoidy is the result of increased transcription from the algD gene and is activated by the transcriptional regulator AlgR. Mutations in algR result in a nonmucoid phenotype and loss of twitching motility. Additionally, AlgR controls transcription of algC, encoding a dual-function enzyme necessary for both lipopolysaccharide (LPS) and alginate production. Therefore, to determine the effect of algR on P. aeruginosa virulence, an algR mutant was examined for sensitivity to reactive oxygen intermediates, killing by phagocytes, systemic virulence, and the ability to maintain a murine lung infection. We found that P. aeruginosa PAO700 (algR::Gm(r)) was less lethal than PAO1, as tested in an acute septicemia infection mouse model, and was cleared more efficiently in a mouse pneumonia model. Additionally, the algR mutant (PAO700) was more sensitive to hypochlorite. However, PAO700 was more resistant to hydrogen peroxide and killed less readily in an acellular myeloperoxidase assay than PAO1. There was little difference in killing between PAO1 and PAO700 with macrophage-like J774 cells and human polymorhonuclear leukocytes. Two-dimensional gel analysis of P. aeruginosa algR mutant and wild-type protein extracts revealed 47 differentially regulated proteins, suggesting that AlgR plays both a positive role and a negative role in gene expression. Together, these results imply that AlgR is necessary for virulence and regulates genes in addition to the genes associated with alginate and LPS production and pilus function.

Conservative management of ingested foreign bodies

We reviewed the clinical benefits of hospitalization, esophagogastroduodenoscopy, and surgical intervention for ingested foreign bodies in adults. Patients with esophageal foreign bodies were not included in the study group. A 10-year experience is reported. Each patient's physical examination findings at presentation, white blood cell count, length of hospital stay, number and types of foreign bodies ingested, endoscopic interventions, surgical interventions, and complications were reviewed. There were 75 separate hospitalizations, all occurring in 22 male prison inmates. A total of 256 foreign bodies were ingested. Patients incurred 281 hospitalization days (average 3.7 days per admission). One patient had signs of peritonitis. White blood cell count was less than 10 K/microL in 85%. Sixty-four endoscopies were performed with removal of 79 of 163 foreign bodies (48% success rate). Five patients required general anesthesia because of a lack of cooperation. Complications occurred in four of them, one requiring laparotomy. Eight additional laparotomies were performed. One was performed for an acute abdomen on admission and one for the development of an acute abdomen after conservative management. Two were performed to remove metal bezoars. Four additional laparotomies were performed because of surgeon preference. Among the 23 patients admitted and managed conservatively, 77 (97%) of 79 foreign bodies passed spontaneously. One patient required laparotomy. Of the 256 ingested foreign bodies, 79 were removed endoscopically, 71 were removed surgically, and 106 passed spontaneously. The size, shape, and number were not predictive of the ability to transit the gastrointestinal tract. Foreign body ingestion is problematic in prison inmates. With conservative management, most foreign bodies will pass spontaneously. Endoscopy has a high failure rate and is associated with significant complications. Surgical intervention should be reserved for those who have acute conditions in the abdomen or large bezoars.

Mechanisms of bacterial pathogenicity

Pathogenic bacteria utilise a number of mechanisms to cause disease in human hosts. Bacterial pathogens express a wide range of molecules that bind host cell targets to facilitate a variety of different host responses. The molecular strategies used by bacteria to interact with the host can be unique to specific pathogens or conserved across several different species. A key to fighting bacterial disease is the identification and characterisation of all these different strategies. The availability of complete genome sequences for several bacterial pathogens coupled with bioinformatics will lead to significant advances toward this goal.

Geriatric trauma: review and recommendations

Although the elderly make up about 12% of the US population, they account for nearly 33% of health care resources expended on trauma. A review of the literature in the area of geriatric trauma revealed a number of factors that influence the likelihood of injury in the elderly population. These include age-related changes in postural stability, balance, motor strength, and coordination that may predispose individuals to falls and other accidents. It is important to have a high index of suspicion for injury and a low threshold for invasive monitoring and transfer to an intensive care setting. Considerations in the care of elderly trauma patients include comorbid conditions, pre-injury medications, reduced physiologic reserve, and the physical changes of aging.

Dual regulation of mucoidy in Pseudomonas aeruginosa and sigma factor antagonism

The conversion to mucoid, exopolysaccharide alginate-overproducing phenotype in Pseudomonas aeruginosa during chronic respiratory infections in cystic fibrosis patients occurs via mutations that activate the alternative sigma factor AlgU (sigmaE). In this study, we demonstrate that conversion to mucoidy can be caused via a second, algU-independent pathway, in which alginate production and transcription of the critical algD promoter depend on another alternative sigma factor, RpoN (sigma54). The algD promoters dependent on sigma54 and sigmaE showed a complete overlap resulting in identical mRNA 5' ends. The two pathways were not independent, as sigma54 also repressed sigmaE-dependent transcription of algD both in vitro and in vivo. The negative regulatory effect of sigma54 on sigmaE-dependent algD expression was based on sigma54 binding to the algD promoter and its interference with sigmaE-dependent transcription. This phenomenon, referred to here as sigma factor antagonism, reflects the unique properties of sigma54, which lacks an intrinsic ability to form open transcription initiation complexes. We propose that this peculiar feature of sigma54 has evolved in part to allow its recruitment as a repressor of certain promoter subsets. The repression of algD by sigma54 also depends on environmental conditions, supporting the notion that sigma factor antagonism plays a physiological role in controlling alginate production in P. aeruginosa during adaptation to different ecological sites (e.g. biofilm development, stress and other growth conditions) and unique environments in the chronically infected host.

Formal swallowing evaluation and therapy after traumatic brain injury improves dysphagia outcomes

BACKGROUND

The incidence of swallowing dysfunction after brain injury is unknown. The efficacy of dysphagia therapy is also unknown. We reviewed our experience to define the incidence of swallowing dysfunction and efficacy of therapeutic intervention.

METHODS

Patients with brain injury sustained between January of 1996 and December of 1997 were reviewed. All were screened with trials of oral intake. Abnormal findings were confirmed with a videofluoroscopic swallow study. Standard therapies included diet, posture, and behavior modifications.

RESULTS

A total of 47 patients were evaluated. Bedside evaluations were normal in 14 patients, 2 patients had overt aspiration and underwent gastrostomy, and 31 patients were referred for a videofluoroscopic swallow study (66%). The videofluoroscopic swallow study was abnormal in 22 of 31 patients (71%). Of these, 4 additional patients required gastrostomy, 13 patients had laryngeal penetration or minor aspiration responsive to dysphagia therapy and were fed. Five other patients had silent aspiration and were fed by means of nasogastric tube; these five patients responded to dysphagia therapy and were able to resume oral intake.

CONCLUSION

Dysphagia is common after severe head injury. With formal swallowing service intervention, aspiration is avoided. Therapeutic interventions can be used to restore oral intake.

Toxic epidermal necrolysis: an analysis of referral patterns and steroid usage

Toxic epidermal necrolysis (TEN) is an exfoliative disorder associated with epidermal slough and systemic toxicity. As of 1986, the literature has advocated early burn center transfer and has rejected the use of steroids. We questioned whether therapy for TEN has changed to reflect these concepts. All cases of TEN referred to our tertiary burn center since 1988 were reviewed. The history was evaluated for steroid usage and timing of burn center transfer. Drug exposures, septic complications, and deaths were noted. Statistics are expressed as mean +/- SD. Fourteen cases of TEN were identified. Transfer was delayed more than 2 days in 10 (72%) instances. Mean delay was 4.4 +/- 2.7 days. Half received steroids. There were three deaths (21%). Pneumonia developed in five patients (36%), urinary tract infections developed in three (21%) patients, seven (50%) patients required intubation, and three (21%) required hemodialysis. No differences in mortality rates or infectious complications were noted in patients who received steroids or who were transferred late. Septic complications occur frequently in TEN. Delay in transfer and initiation of steroids at referring institutions are common. Early burn center referral and avoidance of steroids needs to be reiterated at the level of the referring physician.

Pseudomonas aeruginosa in cystic fibrosis: role of mucC in the regulation of alginate production and stress sensitivity

Alginate production in Pseudomonas aeruginosa and the associated mucoid phenotype of isolates from cystic fibrosis patients are under the control of the algU mucABCD cluster. This group of genes encodes AlgU, the P. aeruginosa equivalent of the extreme heat shock sigma factor sigma E in Gram-negative bacteria, the AlgU-cognate anti-sigma factor MucA, the periplasmic protein MucB and a serine protease homologue, MucD. While mucA, mucB or mucD act as negative regulators of AlgU, the function of mucC is not known. In this study the role of mucC in P. aeruginosa physiology and alginate production has been addressed. Insertional inactivation of mucC in the wild-type P. aeruginosa strain PAO1 did not cause any overt effects on alginate synthesis. However, it affected growth of P. aeruginosa under conditions of combined elevated temperature and increased ionic strength or osmolarity. Inactivation of mucC in mucA or mucB mutant backgrounds resulted in a mucoid phenotype when the cells were grown under combined stress conditions of elevated temperature and osmolarity. Each of the stress factors tested separately did not cause comparable effects. The combined stress factors were not sufficient to cause phenotypically appreciable enhancement of alginate production in mucA or mucB mutants unless mucC was also inactivated. These findings support a negative regulatory role of mucC in alginate production by P. aeruginosa, indicate additive effects of muc genes in the regulation of mucoidy in this organism and suggest that multiple stress signals and recognition systems participate in the regulation of algU-dependent functions.