High Prevalence of Biofilm-Forming MRSA in the Conjunctival Flora in Chronic Dacryocystitis

Objectives: To report the microbiological spectrum of conjunctival flora and prevalence of biofilm-forming Methicillin-resistant Staphylococcus aureus (MRSA) in conjunctival flora in chronic dacryocystitis.

Design: Prospective, case-control study.

Methods: We included patients with unilateral chronic dacryocystitis, and their unaffected eyes as control. Microbiological profile and antibiotic susceptibility of the isolates was determined by standard microbiological procedures. S. aureus isolates were further evaluated for Methicillin resistance by Oxacillin resistance screening agar method and mecA polymerase chain reaction (PCR) and for biofilm synthesis by Congo red agar method, Microtitre plate (MTP) assay, and ica A and ica D PCR.

Results: We found 95 patients with unilateral chronic dacryocystitis. Aerobic Gram-positive isolates (74.2%, n = 72) were more than Gram-negative (25.7%, n = 25) or anaerobic isolates (20.5%, n = 25). S. aureus was most common (46.4%, n = 45), followed by Pseudomonas aeruginosa (10.3%, n = 10). Gram-positive isolates showed highest sensitivity to Linezolid (100%) and higher generation fluoroquinolones. Gram-negative isolates showed good sensitivity (>90%) to all tested antibiotics. S. aureus isolates showed MRSA prevalence as 93.5% and 96.9% by Oxacillin resistance screening agar method and mecA PCR, respectively. Biofilm formation was found in 71.8% MRSA isolates by MTP assay and 58.1% MRSA isolates were resistant to ≥3 classes of antibiotics.

Conclusions: Gram-positive organisms, specifically S. aureus, are the major etiological agent in chronic dacryocystitis. There is high prevalence of MRSA in these isolates and concurrent biofilm formation.     

Epidemiological importance of younger age group during malaria epidemic in PHC Tamulpur, Assam

An investigation of a malaria epidemic was carried out in Tamulpur Primary Health Centre, district Nalbari, Assam during April 1995. The analysis revealed that children between 3 and 12 years of age who were treated and who recovered clinically from fever during the epidemic were instrumental in the progression of the epidemic by acting as Plasmodium falciparum gametocyte reservoirs. Special efforts are required for treatment of children below 12 years during an epidemic.     

Vaccination with a multi-epitopic recombinant allergen induces specific immune deviation via T-cell anergy.

Prophylactic vaccination has recently emerged as a major paradigm toward the prevention and therapy of allergies and asthma; however, the immunological basis of this approach remains to be elucidated. We examined the potential and mechanism of prophylaxis of allergic response in B6D2F1 mice with a multi-epitopic recombinant allergen, rKBG8.3 (MERA-8.3), which represents a major group of allergens of grass pollens, used herein as a model of MERA vaccine. Vaccination (subcutaneous) with soluble MERA-8.3, prior to immunization with the MERA-8.3 in alum, led to suppression of the IgE antibody response and a concomitant increase in IgG2a antibody response specific to the MERA-8.3 in a dose-dependent manner. Analysis of cytokine patterns in spleen and lymph node cells revealed a marked decrease of interleukin-2 (IL-2) and IL-4 production and to a lesser extent a decrease of interferon-gamma (IFN-gamma) synthesis, resulting in an increased ratio of IFN-gamma: IL-4 in vaccinated-immunized mice compared with untreated-immunized control mice. Furthermore, splenocytes of mice treated with the MERA-8.3 alone proliferated to MERA-8.3 in vitro with reduced capacity compared with the splenocytes of MERA-8.3-alum immunized mice, owing to a markedly reduced level of IL-2 production in the former. Collectively, these results suggest that vaccination with the MERA-8.3 induces T-cell anergy, which is pivotal to deviation of specific immunity from Th2- to Th1-like, and may serve as an important approach to prevention and therapy of allergic disorders.     

Superiority of DAT over ELISA as a diagnostic and seroepidemiological tool for the diagnosis of Indian Kala-azar

The aim of this study was to evaluate two methods for the diagnosis of Kala-azar. The sera of 160 individuals were evaluated by ELISA using soluble antigen and direct agglutination test (DAT) for Kala-azar. These were categorized as 100 cases of clinically and parasitologically confirmed Kala-azar and 60 controls. The controls included clinically suspected but parasitologically not confirmed Kala-azar patients (10), endemic normals (15), non-endemic normals (19), typhoid fever (10) and malaria (15). The positivity rate amongst the clinically and parasitologically confirmed Kala-azar patients by ELISA and DAT were 93% and 98% respectively. Out of 10 clinically suspected Kala-azar cases three showed positive reaction in ELISA and two in DAT. Of the endemic normals, one case was found positive by both the tests whereas ELISA was found positive in one additional case. DAT did not show any cross reactivity with malaria while ELISA was found positive in one case. Both endemic normals and typhoid fever cases showed no reaction by both tests. ELISA showed a sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 93%, 90%, 93% and 90% respectively while for DAT these values were 98%, 95%, 98 and 95% respectively. The diagnostic accuracy for ELISA and DAT was found to be 91.9% and 96.9%, respectively. The present study shows that DAT is a simple, sensitive, specific and cost effective test with high PPV and NPV along with approximately 97% diagnostic accuracy and is comparable to ELISA. It may be applied for the routine diagnosis as well as seroepidemiological study of Kala-azar.     

Effects of interferon-α on cytokine profile,T cell receptor repertoire and peptide reactivity of human allergen-specific T cells

A large panel of T cell clones (TCC) specific for the recombinant form of Poa pratensis allergen (rKBG7.2 or Poa p9) were established from the peripheral blood of a grass pollen-sensitive donor in the absence or presence of recombinant interferon-α (IFN-α) in bulk culture and their pattern of cytokine secretion, peptide reactivity and TCR Vβ repertoire was examined. The majority of allergen-specific TCC derived in absence of IFN-α produced high amounts of interleukin-4 (IL-4) and IL-5 but not IFN-γ (Th2 cells), while most of TCC derived in presence of IFN-α produced IFN-γ but not, or limited amounts of, IL-4 and IL-5 (Th1 or Th0 cells). Of 24 TCC established in the presence of IFN-α, 22 were able to recognize a single allergen peptide, p26, while none of the clones established in the absence of IFN-α showed a similar specificity. The majority of both clones expressed the Vβ2 element regardless of whether they were established in the presence of IFN-α, but the presence of IFN-α favored the expansion of Vβ2⁺, Vβ17⁺ and Vβ22⁺ Poa p9-specific T cells, whereas in the absence of IFN-α, other TCR Vβ-bearing T cells (Vβ5, Vβ6.7 and Vβ14) were expanded in addition to Vβ2⁺ T cells. None of Vβ2⁺ clones established in the absence of IFN-α reacted with p26, whereas all the Vβ2⁺ clones established in its presence responded to this peptide. IFN-α also shifted the TCR Vβ repertoire of both Poa p9- and Lolium perenne group 1 (Lol p1)-specific T cell lines generated from the same patient and from a different grass-sensitive individual. These data demonstrate that IFN-α modulates the development of allergen-specific T cells in vitro, and suggest that IFN-α may represent an useful tool for novel immunotherapeutic approaches in allergic disorders.     

Effect of Abiotic Factors on Degradation of Imidacloprid

The role of soil moisture, light and pH on imidacloprid dissipation was investigated. A high performance liquid chromatography (HPLC) based method was developed to quantify imidacloprid present in soil with a recovery of more than 82%. Rate of dissipation of imidacloprid from soil was faster in submerged condition compared to field capacity and air dried condition. Imidacloprid dissipated non-significantly between sterile and non-sterile soils, but at field capacity, the dissipation was faster in non-sterile soil compared to sterile soil after 60 days of incubation. Similarly, under submergence, the dissipation of imidacloprid was 66.2% and 79.8% of the initial in sterile and non-sterile soils, respectively. Imidacloprid was rather stable in acidic and neutral water but was prone to photo-degradation. Therefore, imidacloprid degradation will be faster under direct sunlight and at higher soil moisture.     

Analyses of brain tumor cell lines confirm a simple model of relationships among fluorescence in situ hybridization,DNA index,and comparative genomic hybridization

Several techniques are commonly used for genetic analysis of interphase nuclei. Flow cytometry assays the distribution of DNA content in populations of nuclei stained with a DNA-specific fluorochrome. Fluorescence in situ hybridization (FISH) quantifies the number of copies of a specific DNA sequence in single nuclei. Comparative genomic hybridization (CGH) assesses the relative copy number of DNA sequences throughout a test genome by comparing the signal intensities of test and reference DNA samples hybridized to a template of normal metaphase chromosomes. In principle, there are specific relationships among data obtained from these measurements, and combined measurements should provide a more comprehensive view of the sample that is analyzed. We applied these three techniques to nine brain tumor cell lines and find that a model of CGH that includes unsuppressed repeat sequences describes the data well. We estimate that up to 35% of the fluorescence intensity in well-blocked CGH preparations may not represent unique sequences. Taking these factors into account, our results are, in general, mutually consistent, and highlight issues critical for interpreting CGH preparations. Genes Chromosomes Cancer 20:311-319, 1997. © 1997 Wiley-Liss, Inc.