Biomedical subjects

M E Hamid

Publications and source records attributed to M E Hamid.

17 recordsLinked to original sources

PubMed2006

Unusual manifestation of a concurrent demodectic and sarcoptic mange in a Zebu-Friesian cross-bred heifer.

We describe a rare case of a concurrent demodectic and sarcoptic mange in a 2-year-old heifer in Khartoum, Sudan. The lesions were massive lumps of granulomatous tumour-like dermatitis with thick, nodular folds mainly covering the head, neck and shoulders. Histopathological examination of the lesions revealed the presence of both Demodex bovis and Sarcoptes scabiei. The animal died regardless of the anti-parasitic treatment it received.

Animals↗

PubMed2004

Nocardia farcinica--a significant cause of mastitis in goats in Sudan.

Fifteen of 100 mastitic milk samples from goats suffering from mastitis were tentatively identified as members of the genus Nocardia on the basis of selected phenotypic and chemotaxonomic characteristics. Six of the 155 strains were confirmed as Nocardia farcinica by 16S rDNA gene sequencing and subsequent aligning with relevant actinomycetes found in electronic databases and 2 by other identification criteria. N. farcinica is a serious cause of mastitis with a significant prevalence (15%) among the examined goats. Efforts are needed to optimise and simplify isolation and identification methods.

Animals↗

PubMed2002

Identification of acid fast bacteria from caseous lesions in cattle in Sudan.

One-hundred-and-twenty caseous lesions collected from slaughtered cattle at selected slaughterhouses in Sudan were processed for the detection of acid-fast bacteria (AFB). Sixty-four of the 120 samples showed AFB on microscopic examination after staining with the Ziehl-Neelsen method. Accordingly, it was estimated that 64 (53.3%) of the 120 caseous (purulent) lesions among the samples were due to AFB whereas 56 (46.7%) were due to other causes. Growth on Lowenstein-Jensen slants was obtained in 54 of the 120 samples. The isolated AFB were tentatively identified using microscopic and cultural characteristics. Confirmation of the phenotypic clusters was achieved by analysing the mycolic acids contents and PCR-amplification of the IS6110 insertion sequences. The above two methods have allowed the identification of Mycobacterium bovis and M. farcinogenes, the major AFB isolated from cattle in Sudan. The remaining AFB, which were negative for the above two tests, were further identified by sequencing the 16S rRNA gene. The above strategy thus allowed the identification of the isolated strains as follows: 25 (46%) M. bovis; 21 (39.9%) M. farcinogenes; 4 (7.4%) M. tuberculosis; 1 (1.9%) M. avium; 1 (1.9%) Nocardia sp., 2 (3.7%) unidentified AFB. The isolation of M. farcinogenes and M. tuberculosis, from pulmonary lymph nodes represented important findings.

Animals↗

PubMed2002

Molecular analysis of clinical isolates of Mycobacterium tuberculosis collected from patients with persistent disease in the Khartoum region of Sudan.

SETTING: Patients with positive smears for acid-fast bacilli were enrolled at tuberculosis (TB) clinics in the Khartoum region of Sudan. OBJECTIVE: To identify the presence of drug resistant genotypes in M. tuberculosis isolates which are difficult to treat. METHODS: Genus specific PCR-SSCP was performed to confirm the presence of M. tuberculosis in clinical isolates. Genotypic drug resistance testing was performed by mutation analysis and spoligotyping was used to monitor transmission and to identify epidemic strains. RESULTS: Fifty (48%) of the original 105 samples were classified as M. tuberculosis. Four (4%) of the samples were typed as mycobacteria other than TB, while the remaining (n =50) samples were refractory to further molecular analysis. The fifty amplifiable M. tuberculosis samples were used for subsequent mutation analysis and typing. Mutations were identified in the genes conferring resistance to INH (kat G, 12%), RIF (rpoB, 8%), SM (r psL and rrs, 30%) and EMB (embB, 4%). Two of the samples (4%) had mutations in genes associated to both INH and RIF and can be classified as MDR-TB. Thirty-three percent (13/39) of the persistant tuberculosis cases (5/18 treatment failure; 5/14 relapse; 3/7 defaulter) had mutations accounting for drug resistance. A total of 27 different spoligotypes were identified from 49/50 samples. Twenty-nine (59%) of the isolates were grouped into one of seven clusters, while 20 (41%) showed unique patterns. One patient was infected with M. bovis. CONCLUSION: This is the first molecular approach to characterize clinical isolates of M. tuberculosis from Sudan. The results show that drug resistance is indeed a serious problem and it may compliment the efforts of the National Tuberculosis Programme to improve strategies to control this disease.

Antitubercular Agents↗

PubMed2002

Streptomyces sp., a cause of fistulous withers in donkeys.

Four of 10 donkeys, which showed lesions simulating fistulous withers, were examined clinically with the aim to cultivate and identify the causal agent. Aspiated purulent materials were subjected to bacteriological examination. The causal organisms were recovered in Tryptic Soya agar medium when incubated aerobically at 37 degrees C for up to 5 days. These organisms were found to be actinomycetes-like, Gam positive with stable branching filaments and to form heavy aerial hyphae on colony surface. The isolated organisms ere tentatively identified as Streptomyces sp. on the basis of morphological and cultural characteristics. The initial sequences analysis of the 16S rDNA gene conformed that one of the isolates (SD551) falls within the phylogenetic clade, which encompasses the genus Streptomyces. Studies are underway to further describe the disease and its causal agent. The report represents a good evidence to incriminate Streptomyces in the aetiology of the fistulous withers.

Animals↗

PubMed2001

Nocardia africana sp. nov., a new pathogen isolated from patients with pulmonary infections.

Eight actinomycete strains, isolated from 8 out of 400 sputum samples examined, taken from patients with pulmonary diseases at the Chest Unit of Khartoum Teaching Hospital in the Sudan, were provisionally assigned to the genus Nocardia according to morphological criteria. These isolates were studied further in order to establish their taxonomic status. They were found to have morphological and chemical properties typical of nocardiae and formed a monophyletic clade in the 16S ribosomal DNA tree together with Nocardia vaccinii. The strains showed a unique pattern of phenotypic properties that distinguished them from representatives of recognized Nocardia species, including Nocardia vaccinii. The strains were considered to merit species status and were designated Nocardia africana sp. nov. The findings of the present study are consistent with the view that pulmonary nocardiosis may occur in a substantial proportion of patients who exhibit chronic lung diseases in African countries. It is important, therefore, that clinicians in such countries consider this condition, especially when patients with respiratory infections fail to respond to antitubercular therapy.

Africa↗

PubMed1998

Serotaxonomic analysis of glycolipids from Mycobacterium chelonae-M. fortuitum complex and bovine farcy strains.

The antigenicity and cross-reactivity of glycolipids from strains of bovine farcy and the Mycobacterium chelonae-M. fortuitum complex were analyzed using the ELISA technique. Purified alkali-stable glycopeptidolipids (GPLs) with a characteristic dimethylrhamnosyl sugar unit extracted from M. abscessus, M. chelonae, M. peregrinum and M. senegalense, gave very strong reactions with sera against members of the same four species. Particularly strong cross-reactions were evident between M. peregrinum and M. senegalense. These GPLs reacted more weakly with antisera against the other mycobacteria tested, though clear reactions were noticed with M. farcinogenes and M. fortuitum and also with M. bovis BCG, M. phlei, and M. tuberculosis strains. Alkali-labile diacyl trehalose (DAT) and triacyl trehalose (TAT) from M. fortuitum reacted with homologous sera, and with that against M. tuberculosis. Traces of uncharacterized acyl trehaloses isolated from two strains of M. farcinogenes gave comparatively weak reactions. Mycobacteria labeled M. farcinogenes and M. senegalense produced glucosylated trehalose-based glycolipids (GTs) and the studies showed that the major type was antigenic. These glycolipids cross-reacted strongly with M. senegalense NCTC 4524 but not with the type strain of M. senegalense. On the basis of the chemical patterns and the antigenicity of the GPLs it is evident that M. peregrinum and M. senegalense are particularly closely related and these species show a very close affinity to M. abscessus-M. chelonae.

Animals↗

PubMed1998

Differentiation of phylogenetically related slowly growing mycobacteria based on 16S-23S rRNA gene internal transcribed spacer sequences.

Interspecific polymorphisms of the 16S rRNA gene (rDNA) are widely used for species identification of mycobacteria. 16S rDNA sequences, however, do not vary greatly within a species, and they are either indistinguishable in some species, for example, in Mycobacterium kansasii and M. gastri, or highly similar, for example, in M. malmoense and M. szulgai. We determined 16S-23S rDNA internal transcribed spacer (ITS) sequences of 60 strains in the genus Mycobacterium representing 13 species (M. avium, M. conspicuum, M. gastri, M. genavense, M. kansasii, M. malmoense, M. marinum, M. shimoidei, M. simiae, M. szulgai, M. triplex, M. ulcerans, and M. xenopi). An alignment of these sequences together with additional sequences available in the EMBL database (for M. intracellulare, M. phlei, M. smegmatis, and M. tuberculosis) was established according to primary- and secondary-structure similarities. Comparative sequence analysis applying different treeing methods grouped the strains into species-specific clusters with low sequence divergence between strains belonging to the same species (0 to 2%). The ITS-based tree topology only partially correlated to that based on 16S rDNA, but the main branching orders were preserved, notably, the division of fast-growing from slowly growing mycobacteria, separate branching for M. simiae, M. genavense, and M. triplex, and distinct branches for M. xenopi and M. shimoidei. Comparisons of M. gastri with M. kansasii and M. malmoense with M. szulgai revealed ITS sequence similarities of 93 and 88%, respectively. M. marinum and M. ulcerans possessed identical ITS sequences. Our results show that ITS sequencing represents a supplement to 16S rRNA gene sequences for the differentiation of closely related species. Slowly growing mycobacteria show a high sequence variation in the ITS; this variation has the potential to be used for the development of probes as a rapid approach to mycobacterial identification.

Base Sequence↗

PubMed1995

A new group (type 3) of Mycobacterium celatum isolated from AIDS patients in the London area.

We describe a new group (type 3) of the recently proposed species Mycobacterium celatum isolated from eight patients with AIDS in London, England. Sequences of genes coding for 16S rRNA (EMBL accession no. Z46664) showed a divergence of 17 bases from M. celatum type 2 reference isolates and a divergence of 7 bases from M. celatum type 1 reference isolates. A reference strain is available (NCTC 12882).

Acquired Immunodeficiency Syndrome↗

PubMed1995

Rapid growth and increased biomass yield of Mycobacterium farcinogenes and some related taxa in broth and agar media.

A broth medium containing yeast extract (4 g/l), glucose (15 g/l), magnesium sulphate (0.5 g/l), tri-sodium citrate (1.5 g/l), potassium sulphate (0.5 g/l), ammonium ferric citrate (trace) and buffered with potassium di-hydrogen phosphate (5 g/l) was formulated and found to support a luxuriant growth of Mycobacterium farcinogenes strains that was superior to the conventional media used before. Similar results were obtained with M. senegalense strains and with representatives of the genera Gordona, Mycobacterium, Nocardia, Rhodococcus and Tsukamurella. Out of 13 diverse agar-based media, M. farcinogenes was found to grow particularly well on Mueller Hinton's medium, followed, in order of decreasing growth rate, by modified Bennett's, DST, tryptic soya and glucose yeast extract agars.

Animals↗

PubMed1994

Characterization of the specific antigenicity of representatives of M. senegalense and related bacteria.

Representative strains of M. senegalense and an unusual strain, labelled M. farcinogenes (M280) were examined by thin-layer chromatography for the presence of characteristic surface glycolipids. In the case of M. farcinogenes M280 and M. senegalense M264, the glycolipids were of the alkali-labile acyltrehalose lipooligosaccharide (LOS) class of antigens, whereas M. senegalense M263 was found to contain the alkali-stable glycopeptidolipids (GPL). Through a combination of 1H-NMR, methylation analysis, FAB/MS, and other analytical techniques, the structures of these glycolipids were deduced. The LOS glycolipids were found to be similar in structure to the characteristic glucosyltrehalose-based glycolipids isolated previously from clinical isolates of M. fortuitum, but distinct from the diacyltrehaloses characteristic of the type strain of M fortuitum. The glycopeptidolipids from M. senegalense M263 were closely similar to those characterized previously from M.

Animals↗

PubMed1994

Rapid characterisation and identification of mycobacteria using fluorogenic enzyme tests.

Sixty representatives of selected Mycobacterium and Nocardia species were examined for their ability to cleave 79 fluorogenic synthetic enzyme substrates based on the fluorophores 7-amino-4-methylcoumarin and 4-methylumbelliferone. The resultant data were analysed using the simple matching coefficient and clustering achieved using the unweighted pair group method with arithmetic averages algorithm. Clusters corresponding to the validly described species Mycobacterium bovis, M. chelonae, M. chitae, M. farcinogenes, M. fortuitum, M. peregrinum, M. senegalense, M. smegmatis, Nocardia asteroides, and N. farcinica were circumscribed at or above the 83% similarity level. Fluorogenic probes prepared from 7-amino-4-methylcoumarin and 4-methylumbelliferone provide a rapid means of detecting taxonomically useful enzymes in small amounts of whole mycobacteria and nocardiae.

Clinical Enzyme Tests↗

PubMed1993

Rapid identification of streptomycetes by artificial neural network analysis of pyrolysis mass spectra.

An artificial neural network was trained to distinguish between three putatively novel species of Streptomyces using normalised, scaled prolysis mass spectra from three representative strains of each of the taxa, each sampled in triplicate. Once trained, the artificial neural network was challenged with spectral data from the original organisms, the 'training set', from additional members of the putative novel taxa and from over a hundred strains representing six other actinomycete genera. All of the streptomycetes were correctly identified but many of the other actinomycetes were mis-identified. A modified network topology was developed to recognise the mass spectral patterns of the non-streptomycete strains. The resultant neural network correctly identified the streptomycetes, whereas all of the remaining actinomycetes were recognised as unknown organisms. The improved artificial neural network provides a rapid, reliable and cost-effective method of identifying members of the three target streptomycete taxa.

Actinomycetales↗

PubMed1993

Thin-layer chromatographic analysis of glycolipids and mycolic acids from Mycobacterium farcinogenes, Mycobacterium senegalense and related taxa.

Seventy-nine representative strains of Mycobacterium farcinogenes, Mycobacterium fortuitum, Mycobacterium peregrinum and Mycobacterium senegalense were analysed by thin-layer chromatography for diagnostic glycolipid and mycolic acid patterns. On the basis of glycolipid patterns the 16 M. senegalense strains were assigned to four groups (I, II, III and IV); one strain received as M. farcinogenes had glycolipids that corresponded to those given by the M. senegalense group III strain. Representatives of M. fortuitum produced alkalilabile glycolipids whereas the M. peregrinum strains produced alkali-stable glycopeptidolipids related to those of M. senegalense group I. Members of M. senegalense groups I, III and IV and the M. farcinogenes strains gave the characteristic pattern consisting of alpha- and epoxymycolates on thin-layer chromatographic analysis of the products of alkaline hydrolysis with 5% aqueous tetrabutylammonium hydroxide. Extraction of mycolates from the same strains using acid methanolysis revealed alpha-mycolates and characteristic more polar long-chain components originating from epoxymycolates. In contrast, the M. senegalense group II strains contained an additional more polar omega-1 methoxymycolate that was detected from both acid and alkaline hydrolysates; this spot was also seen in some M. fortuitum and M. peregrinum strains. Preliminary investigations, using a combination of thin-layer chromatography and immunostaining, showed that glycopeptidolipids from M. peregrinum and M. senegalense group I strains were antigenic, a cross-reaction between members of these taxa was shown. In contrast, no reaction was detected between glycopeptidolipids extracted from M. peregrinum and M. senegalense group I strains with antisera from either M. farcinogenes or M. fortuitum.

Animals↗

PubMed1993

A simple chemical test to distinguish mycobacteria from other mycolic-acid-containing actinomycetes.

Two hundred and fifty-two representatives of the general Corynebacterium, Gordona, Mycobacterium, Nocardia, Rhodococcus and Tsukamurella were degraded by alkaline hydrolysis and their mycolic acids extracted as methyl esters following phase-transfer-catalysed esterification. When the mycolic acid methyl esters were treated with a mixture of acetonitrile and toluene all mycobacterial mycolates formed copious white precipitates whereas all but 5 out of the 106 non-mycobacterial mycolates remained in solution. The precipitated methyl mycolates and the dried soluble mycolates were compared by pyrolysis gas chromatography and silica gel thin-layer chromatography. On pyrolysis, the precipitated methyl mycolates from mycobacteria yielded fatty acid methyl esters with 20 to 26 carbon atoms whereas those from the remaining taxa produced shorter-chain esters. Mycobacteria and Tsukamurella paurometabola gave multispot mycolic acid patterns on thin-layer chromatography of their methyl esters whereas those from the remaining strains gave single spots. Our results indicate that Rhodococcus chlorophenolicus strains contain mycolic acids atypical of mycobacteria. It can be concluded that the mycolic acid precipitation test provides a simple and reliable way of distinguishing mycobacteria from all other prokaryotes, notably from other mycolic-acid-containing taxa.

Actinomycetales↗

PubMed1991

Bovine farcy: a clinico-pathological study of the disease and its aetiological agent.

An extensive survey for bovine farcy covering 14,192 animals was conducted in the Sudan. The incidence of the disease was 31.9 per cent in Western Sudan which is regarded as an endemic area. Animals were examined clinically and at post-mortem. The lesions involved the prescapular, femoral, parotid, retropharyngeal, submaxillary, inguinal and mediastinal lymph nodes. Some animals had farcy lesions in the udder and some developed the pulmonary form of the disease. The disease is slow, but progressive in nature and was more prevalent among adult cattle than calves. Mycobacterium farcinogenes was found to be the cause of bovine farcy in the Sudan. The morphological and biochemical characteristics, and the mycolic acid content of the isolated strains were found to be identical to the reference strains of M. farcinogenes and were quite different from reference strains of Nocardia farcinica from which they were easily distinguished by the presence of alpha-mycolate, alpha'-mycolate and epoxymycolate in M. farcinogenes. Hydrolysis of mycolic acids with tetrabutylammonium hydroxide and the precipitation with toluene and acetonitrile gave good results comparable with acid methonalysis and alkaline hydrolysis. Precipitin lines were detected in the sera of some farcy-infected cattle. Histopathological examination of farcy lesions revealed a severe granulomatous reaction characterized by lymphocyte, macrophage, epithelioid and giant cell infiltration as well as marked fibrous proliferation. These changes were indicative of a progressive disease of the delayed tuberculin hypersensitivity type.

Animals↗

PubMed1991

First report of infectious necrotic hepatitis (black disease) among Nubian goats in Sudan.

In a flock of 425 female and male Nubian goats in the Khartoum Province, an outbreak of a disease causing sudden death of 18 apparently healthy goats occurred (11 females and 7 males, 3-6 years old). Adult Fasciola gigantica were found in the livers of all goats and in seven of them Cysticercus tenuicollis cysts. These organs showed necrotic and severe histopathological changes. Clostridium novyi type B was isolated from necrotic areas of all livers and found to be highly pathogenic and toxigenic to laboratory animals. The disease was diagnosed as infectious necrotic hepatitis (black disease). Faecal examination revealed the presence of F. gigantica eggs. Lymnaea natalensis snails were found to be prevalent in the water canals. As the Khartoum Province is regarded as an endemic area for black disease, routine vaccination is highly recommended for its control in goats and sheep.

Animals↗