Medicine
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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty
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Item Detection, identification, and antimicrobial susceptibility of Campylobacter spp. and Salmonella spp. fromfree-ranging Nonhuman Primates in Sri Lanka(Wildlife Disease Association, 2019) Tegner, C.; Sunil-Chandra, N.P.; Wijesooriya, W.R.P.L.I.; Perera, B.V.; Hansson, I.; Fahlman, A.ABSTRACT: Infections with Campylobacter spp. and Salmonella spp. are the most frequently reported causes of human bacterial enteritis. Warm-blooded animals, including livestock, pets, and wildlife, can be carriers of the bacteria and may contaminate the environment and food products. The present study investigated the occurrence of Campylobacter spp. and Salmonella spp. in fecal pat samples from free-ranging toque macaques (Macaca sinica) and tufted gray langurs (Semnopithecus priam) collected in March-May 2015 in Sri Lanka. In 58 samples from toque macaques, Campylobacter jejuni was isolated in 10 (17%), Campylobacter coli in four (7%), and Salmonella enterica subsp. enterica serovar Virchow in two (3%). None of the bacteria were isolated in the 40 samples from tufted gray langurs. Pulse-field gel electrophoresis and multilocus sequence typing identified six profiles and four clonal complexes of C. jejuni. The isolated Campylobacter spp. showed varying susceptibility to antimicrobial substances. All Campylobacter spp. isolates were susceptible to chloramphenicol, erythromycin, florfenicol, gentamicin, and streptomycin. Four of the C. jejuni were resistant to at least one of the following: ampicillin, ciprofloxacin, nalidixic acid, and tetracycline, and one of the isolates was multidrug resistant. All four C. coli were resistant to ampicillin, whereas the two Salmonella Virchow strains were susceptible to all antibiotics tested. The presence of Campylobacter spp. and Salmonella spp. in toque macaques may have an impact on the conservation of endangered primates and public health in Sri Lanka. KEYWORDS: Campylobacter spp .; Antimicrobial resistance; PFGE; Salmonella spp; conservation; nonhuman primates.Item Mycoplasma pneumoniae DNA detection and specific antibody class response in patients from two tertiary care hospitals in tropical Sri Lanka(Microbiology Society, 2018) Wijesooriya, L.I.; Kok, T.; Perera, J.; Tilakarathne, Y.; Sunil-Chandra, N.P.PURPOSE: Respiratory tract infections are a major cause of global morbidity and mortality. Pneumonia is the ninth leading cause of mortality in Sri Lanka. Atypical pathogens cause about one-fifth of community-acquired pneumonia, while Mycoplasma pneumoniae accounts for about 50 %. This study aimed to determine the seroprevalence of M. pneumoniae respiratory tract infections in Sri Lanka while attempting to understand the relationships between the serology and PCR. METHODOLOGY: Paired sera from 418 adult patients (pneumonia, n=97; bronchitis, n=183; pharyngitis, n=138) and 87 healthy controls were studied. IgM, IgG and IgA antibodies were tested by M. pneumoniae enzyme-linked immunosorbent assay (ELISA). Positive IgM and or IgG seroconversion was considered to be seropositive. M. pneumoniae DNA were tested by PCR in age and gender-matched seropositives and seronegatives. RESULTS: M. pneumoniae IgG was in 14.4 % (14/97), 6.0 % (11/183) and 1.5 % (2/138) of pneumonia, bronchitis and pharyngitis patients, respectively, whilst IgM was in 6.2 % (6/97), 1.1 % (2/183) and 0 % (0/138), respectively. Amongst the pneumonia seropositives, 64.7 % (11/17) showed IgG alone, 17.5 % (3/17) showed IgM alone and 17.5 % (3/17) showed IgM and IgG. Amongst the bronchitis seropositives, 84.6 % (11/13) had IgG alone and 15.4 % (2/13) had IgM alone. In the pharyngitis seropositives, only IgG was detected 100 % (2/2). M. pneumoniae DNA was in 52.2 % (12/23) of seropositives and 15.4 % (4/26) of seronegatives. In pneumonia or bronchitis patients, specific DNA was in 77.8 % (7/10) and 50 % (6/12) of patients, respectively. M. pneumoniae DNA was not found in pharyngitis patients. Of the seropositive PCR-negative pneumonia patients, 66.7 % (2/3) showed IgG alone and 33.3 % (1/3)showed IgM alone. In bronchitis patients, 83.3 % (5/6) showed IgG alone and 16.7 % (1/6) showed IgM alone. Of the seronegative PCR-positive patients, 16.7 % (2/12) had pneumonia and 18.2 % (2/11) had bronchitis. CONCLUSION: The serological evidence for M. pneumoniae infection in Sri Lanka comprised the following prevalences: 17.5 % (17/97), 7.1 % (13/183) and 1.4 % (2/138) in adults with pneumonia, bronchitis or pharyngitis, respectively. M. pneumoniae DNA was in 52.2 % (12/23) of seropositives and 15.4 % (4/26) of seronegatives. IgG was predominant in PCR positives and negatives.Item Future trends in veterinary public health and emerging viral diseases(Annual Scientific Sessions of the Sri Lanka Veterinary Association., 2012) Sunil-Chandra, N.P.Veterinary Public Health (VPH) is currently defined as "the slim of all contribusions to the physical, melltal and social well-being of humans through an understanding and application of veterinalry science" (WHO 1999). This definition is more consistent with the values. goals and targets of the WHO vision 'Health for all in the 21 st century". Human health is strongly linked to animal health and production. This link between human and animal populations, and with the surrounding environment. is particularly close in developing regions where animals provide transportation. draught power, fuel and clothing as well as proteins (meat, eggs and milk). In both developing and industrialized countries. however, this can lead to a serious risk to public health with severe economic consequences. A number of communicable diseases known as zoonoses are transmitted from animals to humans. Veterinary medicine has a long and distinguished history of contributing to the maintenance and promotion of public health. Approximately 90 percent of the worldwide burden of all causes of death and disability occur in developing regions of the world but only 10 percent of all health care funds are spent in these regions (WIIO & World Bank). Six communicable disease categories that include pneumonia and infiuenza. AIDS. diarrhoeal disease. tuberculosis. malaria and mcasles are responsible for 90 percent of the estimated 13.3 million deaths in children and young aduits worldwide due to major infectious and parasitic diseases. Zoonotic agents contribute in several of these categories. Livestock disease control programmes in developing countries and countries in transition are often established, even though not very critically, on their economic importance. As a result zoonotic control programmes may not be seriously considered, especially if they do not apparently impact animal heahh and produclion. Obviously, there is a need to be¬ter define the economic impact of zoonoses and other veterinary public health problems with ‘burden of disease' analyses, as used by the World Health Organisation (WHO) and the World Bank.Item Application of Elisa in the diagnosis of rotavirus infections in buffalo calves(An International Journal Of Buffalo Science., 1994) Sunil-Chandra, N.P.; Mahalingam, S.The conditions for diagnosis of group A rotavirus infection in buffalo calves by enzyme linked immunosorbent assay (ELISA) were optimised in terms of type of microtitre plates, all reagents and the cut off points for positivity. Irradiated polystyrene plates were the plates of choice. The optimal dilution for the clinical samples (faecal extracts), capture and detector antibodies and the enzyme conjugate were I : 10, I : 5,000, I : 10,000 and I : 300, respectively. Further, we found that the cut off point for positivity by the screening ELISA was an optical density (OD) of ≥ 0.170 at 450 nm wave length, and for confirmation when blocking activity was ≥ 30%. 'The positivity of a faecal sample was graded as strongly positive if the PIN value was ≥2.7 by screening ELISA and ≥ 50% blocking activity in the confirmatory blocking ELISA. Samples having PIN value < 2.7 but ≥ 2. I and < 50% but ≥ 30% blocking activity were regarded as weakly positive. in addition, pre and post colostral buffalo sel'd as negative and positive control sera respectively, were selected and used for detection of antirotavlral antibodies by the blocking ELISA. 'This study establishes that the ELISA technique can be profitably used (once required parameters are defined), in the diagnosis of rotavirus infection in buffalo calves.Item MURINE GAMMAHERPESVIRUS 68: A MODEL TO STUDY DISEASES OF MAN AND DOMESTIC ANIMALS(Immunobiology of viral infections, 1995) Sunil-Chandra, N.P.; J.P. Simas.; J.K, Fazakerley.; Efstathiou, S.; Nash, A.A.The gamma herpesviruses are widely disseminated in nature causing infection and disease in man. Domestic animals including cattle, deer, sheep, horses and rodents. Murine gammaherpesvirus-68 is a natural pathogen of wild rodents. In Balb/c mice, it establishes a productive infection of epithelial cells of the lung alveoli, and a latent infection of B-Iymphocytes. As with other gammaherpesviruses, chronic infection of mice is associated with Iymphoproliferative disease (LPD) which ranges from mild to high grade lymphomas. In vitro. virus establishes persistent infection in murine myeloma B-cells in which viral DNA exists both in circular form, indicative of a latent infection and linear form, indicative of productive infection. Acyclovir can inhibit virus replication in vivo and in vitro but does not prevent latent infection in mice or reduce circular forms of viral DNA in persistently infected murine myeloma cells. CD8+ T cells are the major effector cells during acute infection. In contrast to the T-cell response which arises promptly to counter infection in the lung and spleen, antibody production (IgM) is first detectable only at 15 to 20 days. MHV-68 infection of mice provides a powerful model to study pathogenesis of gammaherpesviruses, in particular establishment and maintenance of latent infection and virus interaction with the immune system.Item A Novel murine model for studying antiviral compounds against EBV.(International Medical Press, 1994) Sunil-Chandra, N.P.; Barnes, A.G.C.; Nash, A.A.Animal models have been of great importance in for the study of herpes virus parthenogenesis by providing systems with which to investigate basic virological and immunological aspects of acute and latent infection, and also to evaluate chemotherapeutic and vaccination regimens.The best examples are those models used to study acute, latent and recurrent herpes simplex virus (HSV) infection.Item Enteric pathogens of zoonotic concern in non-human primates in Sri Lanka(European Wildlife Disease Association (EWDA, 2016) Tegner, C.; Sunil-Chandra, N.P.; Ingrid, H.; Perera, V.; Wijesooriya, W.R.P.L.I.; Fahlman, A.Zoonotic disease is a two-way street where humans and other animals are interchanging pathogens. We investigated the occurrence of the potentially zoonotic Campylobacter spp., Salmonella spp. and group A rotaviruses in faecal samples from free-ranging toque macaques and tufted gray langurs in Sri Lanka. Samples were opportunistically collected from primate troops with close human contact at five sites. Standardized culturing was used to detect the bacteria and an ELISA-based dipstick test was used for detection of group A rotaviruses antigens. Genotyping was performed using pulse field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) and the isolates' sensitivity to selected antibiotics was tested with VetMIC TM (National Veterinary Institute, Uppsala, Sweden) panels Camp EU, CLIN GN and GN-mo (version 4). All 98 samples tested negative for rotavirus. The 40 samples from gray langurs were also all negative for Campylobacter spp. and Salmonella spp. Of the 58 samples collected from toque macaques, C. jejuni was isolated from ten, C. coli from four and Salmonella enterica enterica subsp. Virchow from two of the samples. The fact that neither of the bacteria were isolated from tufted gray langur samples could reflect a true difference between the primate species. However, this should be interpreted in the light of a relatively small sample size. Resistance to ampicillin, ciprofloxacin, nalidixic acid and tetracycline was identified in four C. jejuni isolates, of which three were multidrug resistant. In addition, all C. jejuni showed undetectable MIC-values to colistin, while all C. coli were sensitive to the substance. All C. coli were resistant to ampicillin. The S. Virchow isolates were sensitive to all antibiotics tested for. Six strains of C. jejuni were identified using PFGE and MLST clonal complexes were assigned to all isolates. Sequence types were assigned to seven out of ten C. jejuni. The detection of antibiotic resistant zoonotic bacteria in free-ranging toque macaques with close human contact may have implications for both non-human primate conservation and public health in Sri Lanka and beyondItem Interactions of murine gammaherpesvirus 68 with B and T cell lines(Academic Press, Elsevier, 1993) Sunil-Chandra, N.P.; Efstathiou, S.; Nash, A.A.Murine gammaherpesvirus is a natural pathogen of wild rodents. We have established that in vivo the virus persists in B lymphocytes in a latent form and therefore has similar biological properties to Epstein-Barr virus and related gamma-I-herpesviruses. In this report we have established a persistent infection in mouse myeloma (B) cells (NSO cell line), but not in mouse thymoma (T) cells (BW 5147 cell line). The virus persists indefinitely in myeloma cells, without any apparent cytopathic effect, but with the production of infectious virus. We demonstrate that ACV abolishes the productive infection, but large numbers of cells harbor the virus in a latent form, as determined by an infectious center assay. Analysis of the viral DNA has shown that during a persistent infection linear virus genomes predominated, with low levels of circular DNA also present. Treatment of cells with ACV results in a significant reduction of linear genomes, but has no effect on the level of circular DNA molecules. These data provide further evidence to support our earlier observations on B cells as the site of latency and provides an in vitro model with which to study the molecular basis of MHV-68 latency/persistence.Item Virological and pathological features of mice infected with murine gamma-herpesvirus 68(Society for General Microbiology; Microbiology Society, 1992) Sunil-Chandra, N.P.; Efstathiou, S.; Arno, J.; Nash, A.A.The primary infection of BALB/c mice with murine herpesvirus 68 (MHV-68) was investigated. When the virus was introduced intranasally, the lung was the main tissue infected, the virus being associated with alveolar epithelium and mononuclear cells. A productive infection lasted for 10 days, after which viral DNA could be detected by in situ hybridization up to 30 days after infection. At that time lymphoproliferative accumulations were also observed in the lung, with formation of germinal centres. Virus could also be recovered from the heart, kidney, adrenal gland and spleen during the primary infection. In addition, the spleen appeared to be the major site of virus persistence, with latently infected cells detected up to 90 days post-infection. During the primary infection, there was atrophy of the thymus and spleen of clinically sick animals. In contrast, lymphoproliferative responses, typified by splenomegaly, were frequently seen in asymptomatic animals. The pattern of infection observed in MHV-68-infected mice is similar to that seen in infectious mononucleosis of man following Epstein-Barr virus infection. The model described in this paper may prove to be useful in studying natural gamma-herpesvirus infections of man and domestic animals.Item Isolation and subgrouping of rotaviruses from buffalo calves in Sri Lanka(British Veterinary Association, Elsevier, 1996) Sunil-Chandra, N.P.; Mahalingam, S.Twenty-eight faecal specimens from Sri Lankan buffalo calves shown to be positive for rotavirus group A antigen were subgrouped by an enzyme-linked immunosorbent assay, by using monoclonal antibodies prepared against subgroup I and II antigens. The 13 of the 28 specimens which were classified as strongly positive belonged to subgroup I. Three of five faecal specimens inoculated on to roller cultures of MA104 cells yielded group A subgroup I rotavirus. As with other group A rotaviruses isolated from human beings and young animals, the buffalo isolates required pre-treatment with trypsin and to have trypsin incorporated in the maintenance medium, and the inoculated cell cultures had to be rolled; at least six serial passages were required before distinct rotavirus cytopathic effects were produced in the MA104 cells.