Effect of basic amino acids on susceptibility to carbapenems in clinical Pseudomonas aeruginosa isolates

We evaluated effects of medium composition, including basic amino acid content and pH, on susceptibility to carbapenems such as imipenem, panipenem and meropenem, in clinical isolates of Pseudomonas aeruginosa. Susceptibility to carbapenems was reduced by basic amino acids in the medium, while susceptibilities to ceftazidime and aztreonam were not. Among carbapenems, susceptibility to panipenem was most sharply reduced by addition of basic amino acids to 1:16 Mueller-Hinton agar (MHA). In 174 of 175 clinical isolates, MICs for carbapenems were affected to different degrees by medium composition. One isolate, in which MICs for carbapenems did not differ between MHA and 1:16 MHA, showed reduced production of porin (OprD). Our results suggest that susceptibility to individual carbapenems, especially panipenem, is difficult to evaluate based on MICs for other carbapenems determined on MHA. For a better prediction of antibiotic efficacy, it may be important to evaluate the susceptibility for each carbapenem individually.     

Bacterial colonization of the uterine cervix and success rate in assisted reproduction: results of a prospective survey

BACKGROUND: Overgrowth of bacteria in the birth canal is associated with an increased risk of late miscarriage, preterm labour, post-partum endometritis and low birthweight. Conception rates in assisted reproduction treatments (ART) remain frustratingly low. We examined whether the nature of bacterial flora, found in the uterine cervical canal at embryo transfer, is associated with the rate of conception in ART. METHODS: We sampled for bacteriological culture the cervical canal of 204 patients who underwent embryo transfer. Of these, 139 (68%) were of fresh embryos, following recent vaginal oocyte retrieval and prophylactic antibiotic therapy, and 65 (32%) of frozen-thawed embryos, without any vaginal intervention in the preceding days. Bacteriological work-up included identification, colony count and antibiotic susceptibility profile. Conception was correlated with bacterial type and colony count. RESULTS: In 75 patients (36.8%) sterile cervical cultures or lactobacillus were recorded. Of these 75 patients, 23 (30.7%) conceived, whereas among the 129 in whom any pathogenic micro-organism was recovered only 21 (16.3%) conceived (P = 0.002). No difference in colonization was found between women who underwent frozen-thawed versus fresh embryo transfer (57 and 67% respectively). Any Gram-negative colonization was associated with no conception. All Gram-positive, and 90% of the Gram-negative bacteria, were sensitive to augmentin. CONCLUSIONS: Failure to conceive in ART is significantly associated with bacterial colonization of the uterine cervix.     

Activities of various β-lactams and β-lactam/β-lactamase inhibitor combinations against Acinetobacter baumannii and Acinetobacter DNA group 3 strains

Acinetobacter baumannii and Acinetobacter DNA group 3 are members of the so-called A. calcoaceticus-A. baumannii complex and are important nosocomial pathogens. Multiresistance in these organisms is increasingly frequent, and alternative treatment options are needed. The beta-lactamase inhibitors clavulanate, sulbactam and tazobactam have intrinsic activity against Acinetobacter strains. In the present study, broth microdilution was used to assess the in-vitro activities of currently available beta-lactam/beta-lactamase inhibitor combinations and sulbactam alone against 469 Acinetobacter isolates (A. baumannii, n=395; Acinetobacter DNA group 3, n=74) collected from various laboratories in Germany. Fixed concentrations and fixed ratios of beta-lactamase inhibitors were used. Sulbactam-containing combinations (susceptibility rates of 90.4-92.7% for A. baumannii and 97.3-100% for Acinetobacter DNA group 3) and sulbactam alone were superior to clavulanate- and tazobactam-containing combinations. The activity of sulbactam-containing combinations against members of the A. calcoaceticus-A. baumannii complex was conferred exclusively by the intrinsic activity of the beta-lactamase inhibitor and did not result from enhanced beta-lactam activity. Testing with the inhibitor added at a fixed ratio of inhibitor to beta-lactam appeared to give more reliable results than testing at a fixed concentration of the inhibitor. Resistance to carbapenems (0.3%) remains low in Germany.     

The molecular immunology of human susceptibility to fungal diseases: lessons from single gene defects of immunity

Introduction: Fungal diseases are a threat to human health. Therapies targeting the fungus continue to lead to disappointing results. Strategies targeting the host response represent unexplored opportunities for innovative treatments. To do so rationally requires the identification and neat delineation of critical mechanistic pathways that underpin human antifungal immunity. The study of humans with single-gene defects of the immune system, i.e. inborn errors of immunity (IEIs), provides a foundation for these paradigms.

Areas covered: A systematic literature search in PubMed, Scopus, and abstracts of international congresses was performed to review the history of genetic resistance/susceptibility to fungi and identify IEIs associated with fungal diseases. Immunologic mechanisms from relevant IEIs were integrated with current definitions and understandings of mycoses to establish a framework to map out critical immunobiological pathways of human antifungal immunity.

Expert opinion: Specific immune responses non-redundantly govern susceptibility to their corresponding mycoses. Defining these molecular pathways will guide the development of host-directed immunotherapies that precisely target distinct fungal diseases. These findings will pave the way for novel strategies in the treatment of these devastating infections.     

Two new mutations and three novel polymorphisms in the<Emphasis Type="Italic"> RB1</Emphasis> gene in Ecuadorian patients

RB1 is the gene responsible for retinoblastoma, the most common malignant intraocular tumor of infancy and early childhood. There are no reports about this gene in Ecuadorian populations, and only a few studies have been published in Latin America about this subject. There is a spectrum of more than 370 mutations described in the RB1 gene mutation database (http://www.d-lohmann.de/Rb/mutations.html), and alterations have been found in 25 of the 27 exons. During the exon-by-exon analysis of 31 tumor and blood samples from Ecuadorian patients, we found two new mutations and three novel polymorphisms. One of the polymorphisms is located in intron 26 where no alterations of the gene have been described previously. The polymorphisms were found in all of the patients tumor samples, but not in normal population, suggesting there might be a relationship between these polymorphisms and the development of retinoblastoma in the Ecuadorian population.The nucleotide sequence data reported are available in the GenBank database under the accession numbers: AY243567, AY260472, AY260473, AY273783     

Different contribution of HLA-DR and -DQ genes in susceptibility and resistance to Insulin-dependent diabetes mellitus (IDDM)

Abstract: Previous studies have indicated that certain alleles of HLA-DR and -DQ genes were strongly associated with susceptibility and resistance to insulin-dependent diabetes mellitus (IDDM), and the role of DQ molecule in IDDM has been suggested. To further clarify the association of DQ alleles with IDDM, we determined the nucleotide sequences of full-length cDNA from 13 DQA1 alleles and 14 DQB1 alleles. The sequencing analysis revealed sequence polymorphisms outside the hypervariable region of DQ genes. We then analyzed the DQA1 and DQB1 polymorphisms along with that of DRB genes in 86 B-lymphoblastoid cell lines (B-LCLs) from various ethnic groups and in healthy unrelated Japanese and Norwegian individuals. The allelic and haplotypic distributions in each population revealed the characteristic haplotypic formation in the HLA class II region. HLA genes in 139 Japanese and 100 Norwegian IDDM patients were analyzed. DQB1*0301 was negatively associated with IDDM in both ethnic groups, irrespective of associated DRB1 and DQA1 alleles. In DQB1*0302 positive populations, which represented a positive association with IDDM in both ethnic groups, DRB1*0401, *0404, *0802 haplotypes increased in the patients, whereas DRB1*0406 haplotype decreased. Considering about the hierarchy in DRB1 alleles with IDDM susceptibility (DRB1*0401>*0404>*0403 in Norwegian and DRB1*0802>*0403>*0406 in Japanese), the genetic predisposition to IDDM is suggested to be defined by the combination of DR-associated susceptibility and DQ-associated susceptibility and by the DQ-associated resistance which is a dominant genetic trait.     

Antimicrobial resistance of nasopharyngeal pneumococci from children from day-care centres and orphanages in Russia: results of a unique prospective multicentre study

This study assessed the antimicrobial resistance of nasopharyngeal pneumococci isolated from children aged < 5 years in day-care centres and orphanages throughout Russia during 2001-2002. Swabs were collected from 2484 children in 43 day-care centres and eight orphanages in 11 cities of European Russia, and from 1669 children in 37 day-care centres and three orphanages in eight cities of Asian Russia, with a total of 1144 and 912 Streptococcus pneumoniae isolates being recovered in European and Asian Russia, respectively. All macrolide-non-susceptible (MICs 0.5-128 mg/L) and fluoroquinolone-non-susceptible (ciprofloxacin MICs > or = 4 mg/L) isolates were tested for resistance mechanisms and clonal relatedness. Non-susceptibility rates, by CLSI criteria, were 19.3%, 0.9% and 0.4% for penicillin G, cefotaxime and amoxycillin-clavulanate, respectively. Resistance to macrolides and lincosamides was also relatively low, i.e., < 7% for clindamycin and 14- and 15-membered macrolides. The highest rates of non-susceptibility were for tetracycline and co-trimoxazole (52.0% and 64.5%, respectively). No clones resistant to ciprofloxacin (MICs > or = 8 mg/L) were found, but 1.7% of isolates were non-susceptible (MIC 4 mg/L). No resistance was found to levofloxacin, gemifloxacin, telithromycin or vancomycin. Pulsed-field gel electrophoresis analysis showed no relationship between ciprofloxacin- and macrolide-non-susceptible isolates in European and Asian Russia. Resistance among macrolide-resistant isolates resulted mostly from the presence of erm(B) and mef(A), and from changes in L4; additionally, L22 mutations were common in isolates from Asian Russia. Non-susceptibility to quinolones was associated with mutations in parC and parE among European isolates. Asian Russian isolates had mutations in parC and gyrA, and alterations in parE were more common. There were substantial differences in non-susceptibility and mechanisms of resistance between pneumococci from Asian and European Russia, with orphanages appearing to be 'hot-spots' of resistance.     

Polymorphic metabolizing genes and susceptibility to atherosclerosis among cigarette smokers

Atherosclerosis (AR) is the leading cause of morbidity and mortality in the US and cigarette smoking is a major contributing factor to the disease. Like cigarette smoking in lung cancer, genetic susceptibility may be an important factor in determining who is more likely to develop AR. However, the current emphasis has been on susceptibility based on altered cardiovascular homeostasis. In this investigation, we studied 120 AR patients and 90 matched controls to elucidate the association between polymorphisms in some metabolizing genes (GSTM1, GSTT1, CYP2E1, mEH, PON1, and MPO) and susceptibility to AR. We found that the GSTT1 null allele and the fast allele of mEH(*) (exon 4) are associated with risk for AR. Furthermore, the combined genotypes GSTM1 null/ CYP2E1(*)5B, GSTM1 null/mEH YY, and GSTT1 null/mEH YY are significantly associated with susceptibility to AR (OR = 15.42, 95% CI = 1.33-77.93, P = 0.021; OR = 3.48, 95% CI = 1.63-8.04, P = 0.0008; OR = 3.4; 95% CI = 0.99-17.38, P = 0.05; respectively). We have also conducted cytogenetic analysis to elucidate if induction of chromosome aberrations (CAs) is a biomarker of AR susceptibility. We found that among cigarette smokers (AR patients and smoker controls), individuals having the GSTM1 null allele had a significantly higher frequency of CAs compared to those with the normal allele (P < 0.05). This association was not found among nonsmokers. In addition, individuals who had inherited the CYP2E1(*)5B allele exhibited a significantly higher CA frequency (8.0 +/- 0.82) compared to those with the CYP2E1 wild-type genotype (4.31 +/- 0.35). Since the analysis of genetic susceptibility factors is still in its infancy, our study may stimulate additional investigations to understand the roles of genetic susceptibility and cigarette smoking in AR.     

Molecular analysis of HLA-D region genes in seropositive rheumatoid arthritis

Analysis of HLA DRB1 and DQB1 Bam HI RFLPs revealed four DRB1 (4.8, 5.2, 6.0 and 7.0 kb) fragments and a 3.2 kb DQB1 fragment to be significantly increased in Caucasians with seropositive RA compared to healthy individuals. The 4.8, 5.2 and 7.0 kb DRB1 fragments were found in 86.5% of RA patients and in 56% of the controls (p = 10(-3), relative risk (RR) = 5.0), while the 6.0 kb fragment was found in 79% of RA patients compared to 32% of controls (p = 2 x 10(-5), RR = 8.0). The 3.2 kb DQB1 fragment was observed in 63.5% of RA patients versus 38.0% of controls (p = 10(-2), RR = 2.8). Analysis of these fragments relative to HLA phenotypes revealed that the 4.8, 5.2 and 7.0 kb DRB1 fragments were strongly correlated with DR4, -7, -9 and -w53 serotypes, the 6.0 kb RFLP with DR4 and the 3.2 kb DQB1 fragment with DR1 and DQw1. Using probes specific for the 5' or 3' regions of the DRB1 gene, the 5.2 and 6.0 kb DRB RFLPs were mapped to the 5' end and the 4.8 and 7.0 kb RFLPs to the 3' end of the DRB1 gene. A probe generated from the second exon of the DRB4 (DRw53) gene recognized only the 5.2 and the 6.0 kb RFLPs corroborating the 5' location of these RFLPs. Family studies further confirmed that these RFLP's segregated with HLA phenotypes.     

支气管肺发育不良基因表达调控异常研究进展

支气管肺发育不良(BPD)是早产儿最常见的慢性肺部疾病。BPD由多种因素引起,其本质是在遗传易感性的基础上,各种环境因素引起的肺损伤和发育中的未成熟肺修复之间的不平衡。研究显示BPD致病分子机理多涉及炎症细胞因子、非编码RNA和各种信号通路因子的异常表达调控。这些相关基因的异常表达,不仅影响了胚胎或早期胎儿肺的正常发育,并阻碍了新生肺损伤后肺的修复,或导致肺功能不全。单独或协同影响了BPD的发生发展。同时研究发现环境风险因素如高氧暴露、炎症导致基因表达异常也是BPD发生的原因之一,环境和基因共同作用推动了BPD的发生发展。