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.     

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.     

Changes in Streptococcus pneumoniae serotypes causing invasive disease with non-universal vaccination coverage of the seven-valent conjugate vaccine

The pneumococcal seven-valent conjugate vaccine (PCV7) has been administered in Portugal since late 2001 through the private sector. To evaluate the impact of PCV7 use, the serotypes and antimicrobial susceptibility of pneumococci causing invasive disease in Portugal during 2003–2005 were determined and compared with available data for the period 1999–2002. Changes in serotype distribution compatible with the introduction of PCV7 were shown for children ≤5 years of age from 2003 onwards and for adults from 2004 onwards. PCV7 use with coverage of 43% of children with four doses in the 2004 birth cohort, although substantially below universal coverage, seems to have contributed to greatly reducing the proportion of invasive infections due to vaccine serotypes  4, 6B, 14 and 23F. Similarly, significant indirect effects on the serotype distribution of pneumococci causing infections in adults were noted, with reductions in the proportion of invasive infections caused by serotypes  4, 5 and 14. These changes were accompanied by an increase in the proportion of two non-vaccine serotypes: 19A isolates in all age groups and 7F isolates in adults. Whereas serotypes  6B, 14 and 19A were associated with multidrug resistance, isolates expressing serotypes  4 and 7F were fully susceptible for the most part. There were no changes in the proportion of resistant isolates within each serotype and, in spite of the changes in serotype prevalence, there was not an overall reduction in the proportion of infections caused by resistant pneumococci.     

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     

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.     

Effectiveness and limits of antimicrobial treatment on seminal leukocyte concentration and related reactive oxygen species production in patients with male accessory gland infection

To evaluate whether bacteriological cure, sperm outcome, spontaneous pregnancy rate and white blood cell (WBC)-related reactive oxygen species (ROS) production were related to the extent of the infection and to an intermittent and repetitive antimicrobial treatment, 122 patients with bacterial [>10(5) colony-forming units (CFU)/ml] male accessory gland infections (MAGI) were studied. According to ultrasound criteria, patients had prostatitis (PR, n = 52), prostatovesiculitis (PV, n = 32) or prostatovesiculoepididymitis (PVE, n = 38). Each group was further subdivided into two subsets: one subset (PR, n = 40; PV, n = 20; PVE, n = 25) was given ofloxacin or doxycycline for 14 consecutive days per month for 3 months; the other subset (PR, n = 12; PV, n = 12; PVE, n = 13) received no treatment. The female partners were also treated. All patients were evaluated before, during (1 and 3 months) and after (3 months) treatment. The bacteriological cure rate was the highest (92.5%) after the third antibiotic course in PR, followed by PV (70.4%), and the lowest in PVE (52.0%). At 3 months after therapy discontinuation, some sperm parameters, seminal WBC concentration and ROS generation (assessed in the 45% Percoll fraction) were ameliorated in PR and PV, whereas no improvement occurred in patients with PVE, except for the percentage of coiled tails. Antibiotic treatment in PR and PV patients led to positive effects on sperm output and spontaneous pregnancy rate (40%) by removing pro-oxidant noxae (microbial and/or WBC-related ROS production). The persistent infertility, dyspermia and sperm-derived ROS overproduction in PVE may relate to a significant percentage of antibiotic-independent re-infection and/or to low antioxidative epididymal properties, which persisted following antimicrobial treatment.     

Effects of Bovine Colostrum with or without Egg on In Vitro Bacterial-Induced Intestinal Damage with Relevance for SIBO and Infectious Diarrhea

Small intestinal bacterial overgrowth (SIBO) occurs commonly, is difficult to treat, and frequently recurs. Bovine colostrum (BC) and chicken eggs contain immunoglobulins and other components that possess antimicrobial, immunoregulatory, and growth factor activities; however, it is not known if they have the ability to reduce injury caused by the presence of bacteria associated with SIBO (Streptococcus, Escherichia coli, Staphylococcus, Bacteroides, Klebsiella, Enterococcus, and Proteus) and infectious diarrhea (enteropathogenic Escherichia coli, Salmonella). We examined the effects of BC, egg, or the combination, on bacterial growth and bacteria-induced changes in transepithelial electrical resistance (TEER) and bacterial translocation across confluent Caco-2 monolayers. BC, egg, or the combination did not affect bacterial growth. Adding bacteria to monolayers reduced TEER and (with minor variations among species) increased bacterial translocation, increased monolayer apoptosis (increased caspase-3 and Baxα, reduced Bcl2), increased intercellular adhesion molecule 1 (ICAM-1), and reduced cell adhesion molecules zonulin1 (ZO1) and claudin-1. BC, egg, or the combination reduced these effects (all p < 0.01) and caused additional increases in vascular endothelial growth factor (VEGF) and Heat Shock Protein 70 (Hsp70) expression. We conclude that BC ± egg strengthens mucosal integrity against a battery of bacteria relevant for SIBO and for infectious diarrhea. Oral BC ± egg may have clinical value for these conditions, especially SIBO where eradication of precipitating organisms may be difficult to achieve.