Microbiol. Res., Volume 1, Issue 1 (October 2010) – 7 articles

Yersinia enterocolitica strain 8081, representing the high-pathogenic biotype 1B, harbours three flagellin genes arranged in tandem in the order fliC3, fliC, fliC2. The genes are organized monocistronic but coordinately expressed under the control of the flagellar sigma factor. No sequence data is available on flagellins of low-pathogenic Y. enterocolitica biotypes 2-5 and of biotype 1A strains, appearing non-pathogenic in the mouse infection model. We sequenced the flagellin genes of ten biotype 1A and biotype 4 isolates, respectively. While we could not identify any sequence polymorphism among flagellin genes of biotype 4 isolates, we found that biotype 1A strains harbour three variable flagellin genes. Moreover, three biotype 1A isolates exhibited a rearranged flagellin gene order and at least one rearranged flagellin gene was apparently acquired by horizontal gene transfer. The variability of flagellin genes seems to mirror evolution towards novel flagellin functions. By contrast, strictly conserved flagellins of biotype 4 isolates point at a strong selection pressure such as expected to be imposed by an important function in the context of infection. Full article

Diabetes mellitus has been associated with increased frequency of serious infections which are attributed to immune deficiencies. The aims of this study were to investigate the type, course and outcomes of community acquired infections, and especially bacteremia in diabetics hospitalized for infection. One hundred and thirty-four consecutive patients (67 diabetics and 67 non-diabetics) matched for age, who were admitted to a general District Hospital in Greece due to infection, were included in this case control study. Diabetics presented urinary infections (46.3% vs. 26.8%, p = 0.006), skin infections (9% vs. 0%, p = 0.007) and bacteremia (11.1% vs. 1.5%, p = 0.023) more often than controls. The most common microorganisms in diabetics were Escherichia coli, Klebsiella pneumoniae, Streptococcus species and fungi. Diabetics had a significantly prolonged hospital stay (6.7 ± 5.4 vs. 4.5 ± 2.4, p = 0.003) compared to controls. In-hospital mortality was similar in both groups (10.4% vs. 3%, p = 0.082) but diabetics had an increased risk from death due to bacteremia (Log-odds 4.2, SE = 1.1, p < 0.0001). Although the analyzed cohorts are small, we found that patients with diabetes mellitus have longer hospitalization related to infections and are at increased risk of bacteremia which may result in adverse outcome. Full article

A total of 93 isolates of halophilic and moderately halophilic bacteria were isolated from salted fishes, Scoliodon sp. and Thrissina thryssa obtained from retail fish outlets in Cochin, Kerala, India. The viable count of the bacteria in Scoliodon sp. and Thrissina thryssa ranged from 10³-10⁶ per g. The morphological, biochemical, and physiological investigations were done to characterize the isolates, which showed good growth in medium containing 3-10% (w/v) NaCl at 37 °C. In Scoliodon sp. the maximum of 87.5% isolates were Gram-positive cocci and in Thrissina thryssa 95.5% of the isolates were Gram-positive rods. The optimum conditions such as temperature, pH, and salts (NaCl) were determined. The utilization of organic compounds such as fructose, lactose, glucose, sucrose, arabinose, trehalose, maltose, salicin, mannose, cellobiose, rhamnose, dulcitol, xylose, raffinose, sorbitol, adonitol, inulin, galactose, inositol, mannitol, hydrogen sulfide, nitrate, citrate utilization, MR-VP, triple sugar iron, as well as the hydrolysis of organic compounds such as casein, gelatin, aesculin, starch, Tween 20, and Tween 80 were also investigated. Moreover, an alkalophilic bacterial strain Bacillus halodurans (B. halodurans) was isolated from Thrissina thryssa and confirmed by 16S rDNA analysis. These studies revealed that salted fishes offer an optimal environment for the viable, diverse, potentially and industrially important bacterial community. Full article

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is an emerging health problem with distinct epidemiology. CA-MRSA colonization and infection is associated with risk factors different from healthcare-associated methicillin-resistant S. aureus infection. CA-MRSA strains pre­sent different characteristics to healthcare associated strains in terms of microbiology as well. Moreover, infection as a result of CA-MRSA may be associated with severe infections, in particular necrotizing pneumonia. CA-MRSA strains may produce Panton-Valentine leukocidin, a protein that available data suggest to be associated with the severity of the infection. Although the incidence of CA-MRSA pneumonia is relatively low, it affects mostly young, immunocompetent individuals, and in this respect constitutes a serious and potentially lethal form of community-acquired pneumonia. Current treatment suggested by international consensus guidelines includes linezolid or vancomycin often combined with clindamycin and/or rifampicin. However, clinical studies are required to clarify further therapeutic issues on timing, dosing, and choice of optimum treatment, and whether new therapeutic strategies such as vaccination and immunoglobulins could be useful. In the present review we discuss the microbiology, epidemiology, pathogenesis, and clinical aspects of community-acquired pneumonia as a result of CA-MRSA in respect of management and prevention. Full article

Twenty-five pluritreated patients were examined. Fifty-six percent yielded Helicobacter pylori (H. Pilory); of these, 9 patients showed a concomitant colonization of the three gastric regions. The highest resistance rate was found for metronidazole (71.8%) followed by chlaritromycin (53.1%). Amoxycillin showed the best susceptibility (only 6% of resistance), tetracycline showed 12% of resistant strains and levofloxacin appeared to be a promising antibacterial agent (18% of resistance). The E-test method was shown to be more suitable than disk diffusion technique for resistance testing. Combined resistance to both chlaritromycin and metronidazole appeared in 50% of the strains. The isolates showing this dual resistance are known to be difficult to eradicate. Resistotypes were shown to be genotypically different even if the strains with the resistance to both chlaritromycin and metronidazole are more likely to belong to genotype cagA+ and vacA s1m1. Heteroresistance (different susceptibility of the isolated strains in a single stomach) resulted in 36% of patients with pangastritis. Indeed, the concomitant presence of H. pylori strains in the same subject, either susceptible or resistant or vice versa, may interfere with the eradication outcomes. In our study, antibiotic resistant H. pylori typically develops from pre-existing susceptible strains rather than from co-infection with a different and unrelated strain. In fact, each pair of isolates detected in our 4 patients with heteroresistance belonged to the same genotype (cagA+ s1m2 in patient 1 and cagA+ s1m1 in patients 2, 3 and 4). In conclusion, H. pylori antibiotic resistance does present several issues in pluritreated patients owing to the rapid emergence of multi-resistant strains. Full article

Diagnosis of invasive fungal diseases remains problematic, especially in undeveloped countries. We have developed an enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies to Histoplasma capsulatum using metaperiodate treated purified histoplasmin (ptHMIN). Our ELISA was validated comparing sera from patients with histoplasmosis, related mycoses, and healthy individuals. The overall test specificity was 96%, with sensitivities of 100% (8/8) in acute disease, 90% (9/10) in chronic disease, 89% (8/9) in disseminated infection in individuals without HIV infection, 86% (12/14) in disseminated disease in the setting of HIV infection and 100% (3/3) in mediastinal histoplasmosis. These parameters are superior to the use of untreated histoplasmin in diagnostic ELISAs. The high specificities, sensitivities, and simplicity of our ELISA support further development of a deglycosylated HMIN ELISA for clinical use and for monitoring the humoral immune response during therapy in patients with chronic and disseminated histoplasmosis. Full article

Chemically synthesized peptides are considered as potential reagents for various applications in biological sciences. They mimic naturally occurring peptides or segments of proteins and have emerged as diagnostic reagents and safe immunogens in animal science. Carefully selected peptides resembling authentic epitopes serve as synthetic antigens in diagnostic tests. Synthetic peptide-based vaccines can elicit antibodies against animal pathogens. The early use of synthetic peptides as a vaccine for foot-and-mouth disease stimulated interest in the development of peptide-based diagnostics and immunoprophylactics. The development of a peptide vaccine for canine parvovirus confirmed the usefulness of peptides as immunoprophylactics. Recently, the advent of the technology for the development of multiple antigenic peptides (MAPs) has provided a well-defined method for the production of highly immunogenic peptides and anti-peptide antibodies. Antibodies raised against major epitopes can be used in the detection of the native antigen (virus) in the enzyme-linked immunosorbent assay (ELISA) and other tests, vindicating the usefulness of peptides for safe, chemically defined, non-infectious diagnostics and immunoprophylactics. This article focuses on the methods for selecting and preparing peptides for the predicted epitopes, their characterization and use, and the application of MAPs. Full article