Der Patient mit Ornithintranscarbamylasemangel

Efficacy and safety of i.v. sodium benzoate in urea cycle disorders: a multicentre retrospective study

Background

The efficacy and safety of intra-venous (i.v.) sodium benzoate for treating acute episodes of hyperammonemia in urea cycle enzyme disorders (UCD) is well known. However, published data do not provide a clear picture of the benefits and risks of this drug. We report a retrospective multicentre study on the use of i.v. sodium benzoate in patients treated for UCD between 2000 and 2010 in the 6 French reference centres for metabolic diseases.

Results

Sixty-one patients with UCDs - 22 ornithine transcarbamylase (20 confirmed, 2 suspected), 18 arginino-succinate synthetase, 15 carbamoyl phosphate synthetase, 3 arginosuccinate lyase, 1 arginase deficiency, 1 N-acetylglutamate synthetase, 1 HHH syndrome - required i.v. sodium benzoate over the course of 95 acute episodes (NH3 > 100 μmol/L or high-risk situations, i.e., gastroenteritis, surgery). Forty out of 61 patients experienced only one episode of decompensation (neonatal coma, 68.6 %). The most frequent cause of late decompensation was infection (55.5 %). A loading dose of i.v. sodium benzoate (median 250 mg/kg over 2 h) was administered for 41/95 acute episodes. The median maintenance dose was 246.1 mg/kg/day, administered via peripheral venous infusion in all cases except one via a central line. The total median duration of i.v. sodium benzoate treatment per episode was 2 days (0–13 days). The median durations of hospitalization in intensive care and metabolic units were 4 days (0–17 days) and 10 days (0–70 days), respectively. Eight patients died during the neonatal coma (n = 6) or surgery (n = 2). The median plasma ammonium level before treatment was 245.5 μmol/L (20.0–2274.0 μmol/L); it decreased to 40.0 μmol/L in patients who were alive (13.0–181.0 μmol/L) at the end of treatment with i.v. sodium benzoate. A decrease in ammonium level to ≤ 100 μmol/L was obtained in 92.8 % of episodes (64/69 of the episodes recorded for the 53 surviving patients). Five patients required another treatment for hyperammonemia (sodium phenylacetate + sodium benzoate, haemofiltration). Eighteen side effects were reported related to the i.v. infusion (local diffusion, oedema).

Conclusion

This 10-year retrospective study shows that i.v. sodium benzoate associated with an emergency regimen is an effective and safe treatment for acute episodes of UCD.

Clostridium difficile in the Pediatric Population of Monroe County, New York

BACKGROUND

Clostridium difficile infection (CDI) incidence in hospitalized children has increased over the past decade and disease has been reported in the community. Therefore, population surveillance that includes nonhospitalized cases is important to accurately estimate the burden of CDI in children. We describe the epidemiology of CDI in the pediatric population of Monroe County, New York.

METHODS

Active, laboratory, and population-based surveillance for CDI has been ongoing in Monroe County through the Emerging Infections Program of the Centers for Disease Control and Prevention since 2010. Infants less than 12 months of age are excluded.

RESULTS

In 2010, the incidence of CDI in the pediatric population was 33.8 per 100 000 population, which increased to 45.8 in 2011and remained stable in 2012. Seventy-one percent of the CDI cases were community-associated, 60% had an underlying medical condition, and 71% received antibiotics before their illness. The North American pulsed-field gel electrophoresis type 1 (NAP1) epidemic strain was identified in 27% of cultured stool specimens.

CONCLUSIONS

Clostridium difficile infection has emerged as a disease affecting children in both the community and hospital settings, with a higher proportion of community illness in our population. The majority of children with CDI had chronic underlying conditions and prior antibiotic exposure. To prevent CDI in this population, the judicious use of antibiotics, especially in the outpatient setting, may be the best strategy. Further population-based studies are warranted to determine preventable risk factors for CDI in the pediatric population.

Clostridium difficile Infection in travelers--a neglected pathogen?

BACKGROUND

Until recently, Clostridium difficile infection (CDI) has been mostly diagnosed in hospitalized elderly patients treated with antibacterial agents. The epidemiology of C difficile is changing as the ribotype 027 strain is spreading worldwide, and more infections are diagnosed in patients residing in the community. Although only few data about the epidemiology of CDI in developing countries are available, a number of reports seem to indicate that the incidence of CDI may be high in some such countries. Transmission of CDI may be more common in hospitals that lack the resources for efficient infection control programs. Theoretically, travelers to low-income countries may be exposed to C difficile both in the community and within hospitals.

METHODS

Data for this article were identified by searches of PubMed and MEDLINE, and references from relevant articles using the search terms "clostridium" and "travel." Abstracts were included when related to previously published work.

RESULTS AND CONCLUSIONS

A total of 48 cases of travelers with CDI were located. CDI among travelers was more commonly acquired in low- and medium-income countries, although 20% of all reported cases occurred in travelers returning from high-income countries. All travelers with CDI for whom a detailed history was available acquired the infection in the community. CDI in travelers occurred in relatively young patients and was frequently associated with the empiric use of antibacterial agents, notably fluoroquinolones. A sizable minority of travelers with CDI had no exposure to antibacterial agents at all. The incidence of travel-related CDI is unknown, but may be higher than previously suspected. A prospective study among travelers with unexplained acute or chronic diarrhea is warranted.

Pathology consultation on detection of Clostridium difficile

Laboratory methods for detecting Clostridium difficile have undergone considerable evolution since the organism's etiologic association with antibiotic-associated diarrhea and colitis was established. Clearly, familiarity with the advantages and shortcomings of the various assays is essential for the laboratory director when choosing among these tests. For the consulting pathologist, furthermore, an understanding of the laboratory's role in securing a diagnosis of C difficile infection (CDI) is also required to identify requests for unnecessary testing that may be costly and potentially misleading. The purpose of this article is to highlight the major differences in laboratory test methods for CDI and to review a few commonly encountered provider ordering scenarios.

Comparison of two rapid assays for Clostridium difficile Common antigen and a C difficile toxin A/B assay with the cell culture neutralization assay

We compared 3 rapid assays for Clostridium difficile with a cell culture cytotoxicity neutralization assay (CCNA). Of 600 stool samples, 46 were positive for toxigenic C difficile. Both rapid common antigen assays were highly sensitive (91.3%-100%) and, therefore, were appropriate screening tests. The rapid toxin assay had poor sensitivity (61%) but excellent specificity (99.3%). Testing stools for glutamate dehydrogenase (step 1) and those positive with a rapid toxin assay (step 2) would correctly classify 81% of submitted specimens within 2 hours, including during periods of limited staffing (evenings, nights, and weekends). CCNA could then be used as a third step to test rapid toxin-negative samples, thereby providing a final result for the remaining 19% of samples by 48 to 72 hours. The use of rapid assays as outlined could enhance timely diagnosis of C difficile.

[Ornithine transcarbamylase deficiency in adolescence and adulthood: first manifestation with life-threatening decompensation]

BACKGROUND

Ornithine transcarbamylase (OTC) deficiency is the most frequent innate disorder of the urea cycle and is X-chromosome linked. The disease normally manifests itself shortly after birth and is fatal when untreated. Due to the different expression and X-chromosomal inheritance the manifestation of symptoms can appear later particularly in girls and young women. The first symptoms are non-specific signs of elevated cerebral pressure as a result of a hyperammonemia, which range from nausea and headache up to cerebral herniation with fatal outcome. Measurement of plasma ammonia levels is a simple yet important screening test for patients with unexpected stupor or delirium.

CASE REPORTS

The two case reports show the clinical range from acute decompensation with acute cerebral herniation followed by fatal outcome to recovery under emergency therapy without substantial neurological deficits.

THERAPY

Emergency treatment consists of symptomatic securing of vital parameters and an immediate reduction in the ammonia level using high calorie, protein-free nutrition to avoid catabolism together with administration of arginine, benzoate or phenyl butyrate. In cases of coma with severe cerebral edema and the threat of a herniation reaction or excessive ammonia levels, emergency hemodialysis must be immediately carried out.

CONCLUSIONS

In the clinical routine it is extremely important to consider a metabolic defect at an early phase and among others to determine the ammonia level so that the appropriate treatment can be instigated in time.

Heterogeneity of large clostridial toxins: importance of Clostridium difficile toxinotypes

Clostridium difficile toxinotypes are groups of strains defined by changes in the PaLoc region encoding two main virulence factors: toxins TcdA and TcdB. Currently, 24 variant toxinotypes (I-XXIV) are known, in addition to toxinotype 0 strains, which contain a PaLoc identical to the reference strain VPI 10463. Variant toxinotypes can also differ from toxinotype 0 strains in their toxin production pattern. The most-studied variant strains are TcdA-, TcdB+ (A-B+) strains and binary toxin CDT-producing strains. Variations in toxin genes are also conserved on the protein level and variant toxins can differ in size, antibody reactivity, pattern of intracellular targets (small GTPases) and consequently in their effects on the cell. Toxinotypes do not correlate with particular forms of disease or patient populations, but some toxinotypes (IIIb and VIII) are currently associated with disease of increased severity and outbreaks worldwide. Variant toxinotypes are very common in animal hosts and can represent from 40% to 100% of all isolates. Among human isolates, variant toxinotypes usually represent up to 10% of strains but their prevalence is increasing.