Oxacillin resistant Staphylococcus aureus among HIV infected and non-infected Kenyan patients.

BACKGROUND: Infections due to methicillin resistant S. aureus (MRSA) present global challenges to clinicians since therapeutic options are limited and suboptimal dosing contributes to heightened mortality and increased length of hospital stay particularly among the HIV infected patients. OBJECTIVES: To assess the prevalence and relative risk of MRSA infections in HIV infected patients. DESIGN: Cross sectional analytical study. SETTING: Kenya Medical Research Institute, Opportunistic Infection Laboratories in Nairobi. SUBJECTS: Four hundred and thirty six male and female patients aged one to 65 years, of whom 220 were HIV-infected and 216 were non-infected. RESULTS: There was 436 male (57.1%) and female (42.9%) respondents. The prevalence of MRSA was 26.3% with majority infecting the HIV infected patients (P=0.046). Likewise, the overall Staphylococcal infections were more common in HIV patients (P <0.001). The common test for MRSA oxacillin disk diffusion had a sensitivity and specificity of 100% and 92%. CONCLUSION: HIV is a predisposing factor to Staphylococcal infection and there are indications that treatment with beta-lactam antibiotics may no longer be relied on as sole empiric therapy for several ill HIV patients whose infections may be of MRSA in origin. There is need for an informed choice in administration of appropriate antibiotics in order to minimise treatment failures due to the multidrug resistance and Vanvomycin intermediate S. aureus (VISA) strains. Molecular epidemiology of MRSA strains in understanding new and emerging trends is recommended.

Subclinical nephrotoxicity associated with occupational silica exposure among male Kenyan industrial workers.

OBJECTIVE: To determine early signs of renal injury due to occupational silica exposure. DESIGN: Cross-sectional analytical research. SETTINGS: Kenyatta National Hospital for the referent population and Clayworks ceramics, bricks and tiles factory for the assessment of occupational silica exposure. SUBJECTS: Thirty three non-smoking silica-exposed male industrial workers and 38 non-smoking male referents participated in this study. RESULTS: Silica-exposed males excreted significantly increased levels of U.TP, U.Malb, U.ALP, U.y-GT and U.LDH compared to referent males. Among the silica-exposed males, U.Si negatively correlated significantly with age, U.TP correlated significantly to each of U.ALP and U.LDH. However, no correlation was observed between work duration and U.Si. CONCLUSION: The present study shows that there is associated glomerular and proximal tubular damage among silica exposed workers which is not duration related and is seemingly subclinical and nonprogressive and urinary silica levels appears to be similar in all groups and are not affected by exposure and work duration: the reason for which is unclear.

Environmental and occupational exposure to lead.

OBJECTIVE: To determine the status of environmental and occupational lead exposure in selected areas in Nairobi, Kenya. DESIGN: Cross sectional study. SETTING: Kariobangi North, Babadogo, Waithaka and Pumwani for assessment of environmental exposure to lead (Pb) and Ziwani Jua Kali works for assessment of occupational lead exposure. Olkalou in Nyandarua District was the covariate study area. SUBJECTS: Three hundred and eight children and adults participated. RESULTS: Blood lead levels (BLLs) obtained for the entire sample (n = 308) ranged from 0.4 to 65 microg/dl of blood. One hundred and sixty nine (55%) of the total sample had levels equal to or below 4.9 microg/dl, while 62 (20%) of the sample had levels ranging from 5.0 to 9.9 microg/dl. Blood lead levels above 10 microg/dl were recorded in 77 (25%) of the total sample. Within Nairobi, 32 (15.3%) of the study subjects in areas meant for assessment of environmental lead exposure had levels above the WHO/CDC action levels of 10 microg/dl of blood. The mean BLL for the occupationally exposed (Ziwani Jua kali) was 22.6 +/- 13.4 microg/dl. Among the workers, 89% had BLLs above 10 microg/dl. In general, 15% of the entire sample (for both environmental and occupational groups) in Nairobi had BLLs above 15 microg/dl. The covariate group at Olkalou had a mean BLL of 1.3 +/- 0.9 microg/dl. CONCLUSION: The prevalence of environmental lead exposure to the general public is high in Nairobi compared to Olkalou where non exposure was reported. Occupational lead exposure has been identified to be at alarming levels and urgent intervention measures are recommended.

Microbiological quality and safety of Rastrineobola argentea retailed in Kisumu town markets, Kenya.

OBJECTIVE: To investigate faecal contamination and safety of Rastrineobola argentea sold in retail markets in Kisumu town. DESIGN: This was a repeated cross sectional study and based on random sampling. SETTING: Kisumu city, targeting six markets; Oile, Jubilee, Kibuye, Kondele, Nyalenda and Manyatta. RESULTS: A total of 60 fish samples were analysed. All the fish were found to be contaminated with E. coli, and in addition 6.67% of the fish products tested positive for Salmonella. Shigella was absent in all samples analysed. 26.53% of E. coli isolates tested were resistant to two or more antimicrobial agents tested, with the highest level of resistance detected against cotrimoxazole at 38.76%. The E. coli multiple antibiotic resistance (MAR) index was 0.084 indicating that the contamination was not originating from a high-risk source. A plasmid of approximately 5.6 kb was commonly isolated from E. coli isolates that showed resistance to ampicillin. Plasmids isolated were not transferable by conjugation. CONCLUSION: The presence of Salmonella spp and occurrence of MDR E. coli were identified as some of the possible health risks that may be associated with R. argentea displayed for sale in Kisumu city markets. This possess a real health risk through consumption or directly through contact with the fish products.

Comparative tick counts on game, cattle and sheep on a working game ranch in Kenya.

The main objective of the study was to determine the possible influence of host species on the maintenance of ticks in the field by determining the relative contribution of game animals compared to domestic animals. The study was carried out on a game ranch 32 km south-east of Nairobi. Tick counts were carried out on 30 Zebu cattle (Bos indicus) aged 1 to 3 years and 20 red Maasai sheep (Ovis aries) aged 6 months to 1 year grazing with game animals in a common area for a period of 2 years and these counts were compared with those on eland and Thomson's gazelle. Half-body counts were carried out on the cattle and sheep once every week. To avoid excessive stress, the animals were dipped in amitraz whenever the half body counts exceeded 50 fully engorged female ticks of any species. Tick counts on two wild animal species (eland (Taurotragus oryx) and Thomson's gazelle (Gazella thomsonii)) were carried out during the weekly culling of the herbivores. The results revealed that there was no significant difference in the number ticks per square metre between the wild ungulates and the domestic animals.

Study on the sequential tsetse-transmitted Trypanosoma congolense, T. brucei brucei and T. vivax infections to African buffalo, eland, waterbuck, N'Dama and Boran cattle.

Susceptibility of African buffalo, eland, waterbuck, N'Dama and Boran cattle to sequential Glossina morsitans centralis-transmitted infections of Trypanosoma congolense, T. brucei brucei and T. vivax was compared, and their possible role as reservoirs of these parasites for G. moristans centralis, G. pallidipes, G. austeni, G. brevipalpis and G. longipennis determined. The buffalo, eland, waterbuck and N'Dama controlled T. congolense parasitaemias and were able to prevent anaemia. By contrast, one Boran became severely anaemic whilst the other controlled parasitaemia and anaemia. When the above five species of Bovidae were rechallenged with T. brucei brucei they showed persistent parasitaemias but did not develop anaemia. The buffalo died of other causes. When the remaining four bovids were rechallenged with T. vivax they became infected with mixed T. vivax/T. b. brucei parasites. Eland, waterbuck and N'Dama controlled parasitaemias and anaemia whereas the Boran became anaemic. Cyclical development of T. congolense occurred in G. moristans centralis when fed on the bovid hosts, with buffalo being infective for tsetse flies for a much longer period. There was no relationship between the levels of T. congolense parasitaemia in the bovid hosts and the resultant infection rates in tsetse flies. Glossina m. centralis was more susceptible than G. pallidipes to T. brucei brucei whilst G. austeni the least; G. brevipalpis and G. longipennis were refractory to the mature infection. Again there was no relationship between T. brucei brucei parasitaemia levels in the hosts and infection rates in the flies. Glossina m. centralis and G. pallidipes showed mixed T. brucei brucei/T. vivax infections whilst G. austeni, G. brevipalpis and G. longipennis became infected with T. vivax alone. Tsetse flies showed higher T. vivax infection rates when fed on the hosts with high parasitaemias than thosewith low parasitaemias. Thus trypanotolerant African buffalo, eland, waterbuck, N'Dama as well as some trypanosusceptible Boran cattle can serve as reservoirs of single or mixed trypanosome infections for tsetse flies. This study has also shown that the Ag-ELISA on the sera from the five bovid hosts had low sensitivity and species-specificity. Examinations of thin wet blood films and buffy coats with a phase-contrast microscope were not sensitive enough to detect the parasites on all occasions. Xenodiagnosis using mice for T. brucei brucei and T. congolense infections, and tsetse flies for all the three trypanosome species were most sensitive for the detection of trypanosome infections in the bovid hosts.

Characterization of Theileria parva which infects waterbuck (Kobus defassa).

Theileria-free waterbuck (Kobus defassa) born in captivity were successfully infected with Theileria parva sporozoites derived from ticks infected by feeding on African buffalo (Syncerus caffer). All waterbuck underwent mild infections with the development of sporadic schizont and piroplasm parasitosis when inoculated with sporozoite doses lethal to cattle. A carrier state of T. parva was demonstrated by feeding clean R. appendiculatus nymphs on two of these infected waterbuck. Tick batches from these waterbuck on 2 of 5 occasions transmitted lethal Theileria infections to cattle. In a separate experiment, waterbuck cells were infected and transformed in vitro by T. parva sporozoites derived from buffalo but not by cattle-derived T. parva (Muguga) sporozoites. Waterbuck cells infected in vitro with T. parva isolated from buffalo were inoculated into autologous waterbuck but no infections developed. Theileria parva isolates generated in this study from various sources were characterized using anti-T. parva schizont monoclonal antibodies (MAbs), and it was found that buffalo-derived and waterbuck-passaged isolates had different profiles. Species-specific synthetic oligonucleotide probes, restriction fragment length polymorphism (RFLP) analysis with cloned T. parva DNA probes, and DNA sequence analysis of the p67 sporozoite antigen gene confirmed that the waterbuck-passaged parasite was T. parva. The Tpr repetitive probe hybridization patterns from the waterbuck-passaged parasites were different from the other samples tested. The ribosomal genotype of the waterbuck-passaged T. parva was similar to that of cattle-derived T. parva Muguga. Analyses with both probes and MAbs suggested that a minor parasite population present within the T. parva 7014 buffalo-derived stock had been selected during waterbuck passage.(ABSTRACT TRUNCATED AT 250 WORDS)

Low doses of natural human interferon alpha inhibit the development of Babesia microti infection in BALB/c mice.

Studies were undertaken to determine whether treatments with low doses of natural human interferon alpha (HuIFN-alpha) administered by various routes could inhibit the development of the intra-erythrocytic protozoan Babesia microti in BALB/c mice. HuIFN-alpha treatment given intramuscularly significantly inhibited development of the parasitaemia of the parasite compared with infections in control mice.

A study of autoantibodies to phosphatidyl-serine in Babesia bovis and Babesia bigemina infections in cattle.

Sera from cattle infected with Babesia bovis were found to contain antibodies to phosphatidyl-serine (PS), a negatively charged phospholipid normally found on the internal membrane of erythrocytes. In contrast, no autoantibodies were detected following Babesia bigemina infection indicating that the autoimmunity is not genus specific. During infection with Babesia bovis, PS translocates to the external membrane and it is suggested that this may result in PS behaving as an autoantigen owing to a transitional change. These autoantibodies may also play some role in the pathology of infection, especially the disturbed coagulation system associated with acute Babesia bovis infection.

Isolation, initial characterization and serological studies of glycolipid antigens from Babesia bovis-infected erythrocytes.

Serological analysis of Babesia bovis-derived glycolipids by ELISA and the indirect fluorescent antibody technique demonstrated the existence of their antigenic and immunogenic activities not only in B. bovis but also in B. bigemina infections. This indicates that serological cross-reactivity of B. bovis and B. bigemina relates to glycolipids. The negative ELISA reaction obtained with Anaplasma marginale antisera suggested the specificity of the reaction to the genus Babesia. Fractionation of these glycolipids by Florisil Sep-Pak column chromatography with subsequent HPTLC immunostaining and Orcinol staining suggested the presence of carbohydrate antigenic determinants in B. bovis glycolipids.

Human interferon alpha fails to inhibit the development of Babesia bigemina and Anaplasma marginale infections in cattle.

Studies were undertaken to determine whether human interferon alpha (HuIFN-alpha) administered orally could inhibit the development of clinical disease caused by the intraerythrocytic protozoan Babesia bigemina and the intraerythrocytic rickettsia Anaplasma marginale in cattle. HuIFN-alpha did not inhibit intraerythrocytic multiplication of either of the two parasites, suggesting that there is no role for HuIFN-alpha administered orally in the control of these pathogens.

Serological and immunological studies with a hexane extract of Babesia bovis-infected erythrocytes.

Antigenic and immunogenic activities of a hexane extract from Babesia bovis-infected erythrocytes were investigated. Positive ELISA and IFAT reactions were obtained with bovine antisera to B. bovis and B. bigemina produced by natural infection and rabbit antisera to the hexane extract, respectively. In contrast, negative ELISA reactions were obtained with Anaplasma marginale antisera indicating that the antigen(s) is specific for the genus Babesia. The IFAT clearly demonstrated that the antigen was associated with the parasite and the infected erythrocyte and not present in uninfected erythrocytes. Furthermore, cross-reactions with Babesia bigemina antisera suggested that serological cross-reactivity in bovine Babesia species is at least due in part to lipid or lipid-associated antigens.

Bovine babesiosis: failure to induce interferon gamma production in response to Babesia bovis antigens in cattle.

The immune response to Babesia bovis infection or vaccination was evaluated by measuring antibody and interferon gamma (IFN-gamma) production to protective recombinant and crude native B. bovis antigens. Cells from vaccinated or infected cattle failed to produce detectable IFN-gamma when stimulated with B. bovis antigens in vitro. In contrast, antibody was induced by protective recombinant B. bovis antigens. These findings are consistent with the argument that immunity to B. bovis infection is correlated most strongly with humoral rather than cell-mediated immune responses.