SmaI restriction site-based multiplex PCR for typing of hospital- and community-acquired Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is an important nosocomial pathogen, and morbidity and mortality rates associated with this pathogen have increased markedly in recent years. MRSA strains are generally resistant to several classes of antibiotics and are therefore difficult and costly to treat. A major issue is to identify the sources of MRSA infections and to monitor their epidemic spread. In this study, we report the development of a typing technique for S. aureus, based on single-nucleotide polymorphism (SNP) variations in and around SmaI-restriction sites (CCCGGG). An assessment of the SmaI restriction site-based multiplex PCR (SmaI-multiplex PCR) typing (SMT) with respect to pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) revealed a high level of concordance in the clustering of the test strains. The SmaI-multiplex PCR was found to be more discriminatory than MLST/staphylococcal cassette chromosome mec (SCCmec) typing but less discriminatory than PFGE. SMT can provide real-time information for the investigation of ongoing S. aureus hospital outbreaks. SMT meets the criteria of a practical typing method: it is simple, reproducible, and highly discriminatory and does not require expensive equipment or specialist expertise. Consequently, SmaI-multiplex PCR has the potential to be used in routine clinical microbiology laboratories.     

Investigating transmission of Mycobacterium bovis in the United Kingdom in 2005 to 2008

Due to an increase in bovine tuberculosis in cattle in the United Kingdom, we investigated the characteristics of Mycobacterium bovis infection in humans and assessed whether extensive transmission of M. bovis between humans has occurred. A cross-sectional study linking demographic, clinical, and DNA fingerprinting (using 15-locus mycobacterial interspersed repetitive-unit-variable-number tandem-repeat [MIRU-VNTR] typing) data on cases reported between 2005 and 2008 was undertaken. A total of 129 cases of M. bovis infection in humans were reported over the period, with a decrease in annual incidence from 0.065 to 0.047 cases per 100,000 persons. Most patients were born pre-1960, before widespread pasteurization was introduced (73%), were of white ethnicity (83%), and were born in the United Kingdom (76%). A total of 102 patients (79%) had MIRU-VNTR typing data. A total of 31 of 69 complete MIRU-VNTR profiles formed eight distinct clusters. The overall clustering proportion determined using the n - 1 method was 33%. The largest cluster, comprising 12 cases, was indistinguishable from a previously reported West Midlands outbreak strain cluster and included those cases. This cluster was heterogeneous, having characteristics supporting recent zoonotic and human-to-human transmission as well as reactivation of latent disease. Seven other, smaller clusters identified had demographics supporting recrudescence rather than recent infection. A total of 33 patients had incomplete MIRU-VNTR profiles, of which 11 may have yielded 2 to 6 further small clusters if typed to completion. The incidence of M. bovis in humans in the United Kingdom remains low, and the epidemiology is predominantly that of reactivated disease.     

Neuromodulation and female sexual function: does treatment for refractory voiding symptoms have an added benefit?

Introduction and hypothesis  Women undergoing InterStim implantation for overactive bladder (OAB) or painful bladder syndrome (PBS) were prospectively evaluated to determine if neuromodulation has any effect on female sexual function (FSF). Methods  Sexually active women in our InterStim database completed a female sexual function index (FSFI) preoperatively and at 6 months. Results  Of 105 women, 54 have 6-month follow-up data. Of these, 27 were sexually active preoperatively and at follow-up. The mean (standard deviation (SD)) FSFI improved from 18.7 (6.8) preoperatively to 21.0 (6.0) postoperatively; however, this was not statistically significant (p = 0.220). Subgroup analysis of patients with OAB revealed that mean (SD) FSFI preoperatively was 18.6 (8.0) and 22.4 (6.4) at 6 months (p = 0.257). In the PBS group, mean (SD) FSFI was 18.8 (6.3) preoperatively and 18.7 (5.8) at 6 months (p = 0.98). Conclusions  Neuromodulation does not significantly improve FSF in a heterogenous population. Additional studies are needed to confirm the findings in our study.     

Laparoscopic versus open right hepatectomy: a comparative study

Background

The safety of laparoscopic major liver resections is still uncertain. The aim of this study was to compare our results for laparoscopic right hepatectomy (LRH) with those for open right hepatectomy (ORH).

Methods

Patients undergoing LRH were compared with retrospectively selected patients from our ORH database. The 2 groups were well matched for sex, age, American Society of Anesthesiologists score, body mass index, liver disease, and tumor size. Surgical and postsurgical outcomes were compared.

Results

Seventy-two patients were analyzed: 22 in the LRH group and 50 in the ORH group. Operating time was similar. Blood loss was significantly less in laparoscopic resections (P = .038). Specific morbidity rates were not different, general morbidity was lower after laparoscopy (P = .04), and the severity of postsurgical complications was not different. Mean hospital stay was significantly shorter after laparoscopy (P = .009).

Comments

Laparoscopy improved surgical and postsurgical outcomes for ORH in selected patients. This is the first comparative study to demonstrate an advantage of laparoscopy for a major liver resection. Prospective randomized studies with a greater number of cases are needed to confirm the role of laparoscopy in major liver resections.     

Infantile encephalopathy due to vitamin deficiency in industrial countries

Introduction

Severe avitaminosis causing life-threatening conditions in the infantile age group is extremely uncommon and has been reported in babies with malabsorption receiving prolonged inadequate vitamin supplements.

Case reports

We report two infants who presented with neurological deterioration. Immediate work-up and treatment for infectious and inborn metabolic disorders were initiated and the diagnosis, made with a few days delay, was prolonged avitaminosis of thiamine (B1) and cobalamin (B12). B1 deficiency was suspected when further neurological deterioration was observed during administration of intravenous fluids containing glucose in an infant with high lactate levels in the cerebrospinal fluid. High transketolase activity that normalized after thiamine treatment and the findings in the MRI and MRS of the brain confirmed the suspected diagnosis. B12 deficiency was suspected in an infant of a strict vegetarian mother who presented with neurological deterioration and severe megaloblastic anemia. The diagnosis was confirmed when low serum levels of B12 and methylmalonic aciduria were detected and treatment with B12 resulted in normalization of urinary methymalonic acid.

Conclusion

Avitaminosis, even in industrialized countries, should be considered in an atypical age group with no known risk factors. Early diagnosis and prompt treatment may accomplish a quick recovery with fewer sequelae.

     

Dissecting the effects of mtDNA variations on complex traits using mouse conplastic strains

Previous reports have demonstrated that the mtDNA of mouse common inbred strains (CIS) originated from a single female ancestor and that mtDNA mutations occurred during CIS establishment. This situation provides a unique opportunity to investigate the impact of individual mtDNA variations on complex traits in mammals. In this study, we compiled the complete mtDNA sequences of 52 mouse CIS. Phylogenetic analysis demonstrated that 50 of the 52 CIS descended from a single female Mus musculus domesticus mouse, and mtDNA mutations have accumulated in 26 of the CIS. We then generated conplastic strains on the C57BL/6J background for 12 mtDNA variants with one to three functional mtDNA mutations. We also generated conplastic strains for mtDNA variants of the four M. musculus subspecies, each of which contains hundreds of mtDNA variations. In total, a panel of conplastic strains was generated for 16 mtDNA variants. Phenotypic analysis of the conplastic strains demonstrated that mtDNA variations affect susceptibility to experimental autoimmune encephalomyelitis and anxiety-related behavior, which confirms that mtDNA variations affect complex traits. Thus, we have developed a unique genetic resource that will facilitate exploration of the biochemical and physiological roles of mitochondria in complex traits.The mammalian mitochondrial genome (mtDNA) is a closed, circular, double-stranded DNA with genes encoding mitochondrial oxidative phosphorylation (OXPHOS) enzyme complexes that are essential for ATP production (Anderson et al. 1981). In humans, mtDNA variations can be rare pathogenic mutations or deletions that cause maternally inherited mtDNA disorders or common mtDNA variants that lead to functional changes and thus predispose individuals for polygenic diseases (Wallace et al. 1988; Taylor and Turnbull 2005). However, unique genetic characteristics of mammalian mtDNA, for example, the lack of recombination and the transmission as one haplotype, hamper efforts to identify precisely the variations responsible for traits and effects and to define the biochemical and physiological consequences of individual variations. The same characteristics complicate the genetic manipulation of mtDNA. Although several transmitochondrial mice have been produced, a mouse with a single mtDNA mutation has not yet been generated (Pinkert and Trounce 2002).An unexpected observation provided a potential solution to the limitations of mtDNA. In 1982, Ferris et al. (1982) demonstrated that most mouse common inbred strains (CIS) had the same mtDNA RFLP pattern, which suggested that mouse CIS were descended from a single female. This conclusion was confirmed by sequencing the mtDNA of CIS (Johnson et al. 2001; Bayona-Bafaluy et al. 2003; Mathews et al. 2005; Goios et al. 2007), which also demonstrated that several mutations had accumulated during the establishment of the strains, with a higher ratio of nonsynonymous/synonymous mutations than in wild mice (Goios et al. 2007). Those mutations are of potential functional importance, as has been demonstrated in recent studies (Johnson et al. 2001; Mathews et al. 2005; Moreno-Loshuertos et al. 2006). These findings suggest that the systematic production of conplastic strains (mitochondrial substitution strains) with CIS mtDNA carrying one or more functional mutations would constitute a genetic resource to investigate the roles of individual mtDNA variations in complex traits.In the present study, we report the generation of a unique public resource of 16 conplastic strains that carry potential functional mtDNA mutations on a C57BL/6J genetic background. In humans, mtDNA variations are associated with many neurological diseases such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis (MS), and bipolar disorder (Shoffner et al. 1993; Kalman and Alder 1998; Kato et al. 2001; van der Walt et al. 2003). Recently, we reported that the mtDNA allele nt13708A increases susceptibility to MS (Yu et al. 2008). To test the usefulness of this genetic resource, we investigated the conplastic strains with regard to nervous system phenotypes, in particular experimental autoimmune encephalomyelitis (EAE), a mouse model of MS, and anxiety-like behavior as an aspect of bipolar disorder. We show that mtDNA variations affect both phenotypes, which suggests that conplastic strains are a useful genetic resource for investigating the role of mtDNA in complex traits.