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Biomedical subjects

C Gilks

Publications and source records attributed to C Gilks.

At least 37 records · Page 2Linked to original sources
PubMed1995

Characterization of Streptococcus pneumoniae from human immunodeficiency virus--seropositive patients with acute and recurrent pneumonia.

Thirty-two isolates of clinically significant Streptococcus pneumoniae from 11 human immunodeficiency virus (HIV)-seropositive patients with single or multiple episodes of pneumonia were characterized by antibiotic susceptibility testing, serotyping, ribotyping, and repetitive extragenic palindromic polymerase chain reaction (REP-PCR). The isolates comprised 10 serotypes, 12 ribotyping patterns, and 12 REP-PCR patterns. There was close but not absolute correlation between techniques. By combining these characterization methods, 14 strains were identified. Five strains were found in > 1 patient, suggesting their frequent occurrence in this population. Two isolates of different serotype from 1 patient were highly related by ribotyping and REP-PCR, suggesting possible in vivo serotype change. Acute infection was associated with single strains or coinfection by distinct strains. Recurrent pneumonia was identified as relapse with the same strain or reinfection with new strains. The molecular characterization of pneumonococci from HIV-seropositive persons refines our understanding of pneumonococcal infection in these patients.

Acute Disease↗
PubMed1994

Antimicrobial susceptibility and presence of extrachromosomal deoxyribonucleic acid in Salmonella and Shigella isolates from patients with AIDS.

The development of multi-drug resistance by enteric bacteria is an increasing problem in the developing countries. There is need to monitor antimicrobial susceptibility of these organisms in order to ensure appropriate treatment and control of infections. Antimicrobial susceptibility patterns, plasmid DNA content and restriction enzyme digests of plasmid deoxyribonucleic acid (DNA) were used to study 175 Salmonella and Shigella species isolated from predominantly HIV-seropositive adult patients in Nairobi, Kenya. All the isolates were sensitive to ciprofloxacin. A significantly higher proportion of Shigella species were resistant to chloramphenicol, cotrimoxazole, streptomycin and tetracycline compared to Salmonella species (p-value < 0.001). Multi-resistant Salmonella typhimurium isolates had 60, 40 and 5 MDa plasmids, the 5 MDa plasmid was absent in gentamicin sensitive isolates. In addition to 2-10 MDa range of plasmids, multi-resistant Shigella species had a heavy 100-105 MDa plasmid. Restriction enzyme digests were similar for the 60 and 40 MDa plasmid DNA bands from Salmonella typhimurium isolates but did not show any consistency among Shigella spp. Plasmid-encoded multi-drug resistance plays a major role in the spread of resistance among enteric bacteria. It is vital to use drugs rationally in order to control the emergence and spread of multi-drug resistance.

AIDS-Related Opportunistic Infections↗
PubMed1993

Increased recurrence of tuberculosis in HIV-1-infected patients in Kenya.

There is evidence that in human immunodeficiency virus 1 (HIV-1) infected patients with tuberculosis the rate of recurrence of tuberculosis is increased in those patients treated with a standard thiacetazone-containing regimen. To assess the impact of HIV-1 on tuberculosis in Kenya, patients with tuberculosis were studied prospectively. After treatment with either a standard thiacetazone plus isoniazid regimen or a short-course thiacetazone-containing regimen, overall recurrence rate of tuberculosis was 34 times greater in 58 HIV-1-positive patients than in 138 HIV-1-negative patients (adjusted rate ratio 33.8, 95% CI 4.3-264). Recurrence in the HIV-1-positive group was strongly associated with a cutaneous hypersensitivity reaction due to thiacetazone during initial treatment (rate ratio 13.2, 95% CI 3.1-56.2). In all patients with a cutaneous hypersensitivity reaction ethambutol was substituted for thiacetazone. No significant association was found between recurrence among HIV-1-positive patients and initial resistance, initial treatment regimen, a diagnosis of AIDS (WHO definition), or poor compliance. DNA fingerprinting suggested that both relapse and new infection may have produced recurrence of tuberculosis. In patients who had a cutaneous hypersensitivity reaction, increased recurrence rate may have been related to interruption of treatment, subsequent poor compliance, or more advanced immunosuppression. Alternatively, a change to the combination of ethambutol and isoniazid in the continuation phase for 11 months only may not be adequate.

AIDS-Related Opportunistic Infections↗
PubMed1993

Molecular epidemiology of penicillin-resistant pneumococci isolated in Nairobi, Kenya.

A total of 26% of the pneumococci isolated from an outpatient clinic in Nairobi, Kenya, during 1991 to 1992 had intermediate levels of penicillin resistance. Gene fingerprinting and DNA sequencing were used to distinguish the penicillin-binding protein (PBP) 1A, 2B, and 2X genes in 23 resistant isolates. Isolates were grouped into those that had identical forms of each of the three PBP genes (fingerprint groups) and those that had identical rRNA gene restriction patterns (ribotypes). Both methods divided the isolates into 11 groups. In a few cases, horizontal gene transfer appeared to have distributed an identical altered PBP gene into different pneumococcal lineages. Eight isolates were indistinguishable by ribotyping or multilocus enzyme electrophoresis and contained identical PBP 1A genes. Although these isolates were therefore members of the same clone, they were divided into two fingerprint groups which contained different PBP 2X and 2B genes. Presumably, members of this clone have acquired different altered PBP 2X and 2B genes on two separate occasions. One of these fingerprint groups contained isolates of serotype 14, whereas the other contained isolates of both serotypes 14 and 7. The identification of isolates in the latter group that are identical by all criteria, except serotype, implies the occurrence of a change in serotype. The predominant serotypes of the penicillin-resistant pneumococci from Nairobi were serotypes 14 and 19. In both cases, isolates of the same serotype which required the same MIC of penicillin were not members of a single clone, indicating that identity of serotype and MIC are not sufficient criteria for defining clones of resistant pneumococci even when the bacteria are isolated from a single clinic.

Amino Acid Sequence↗
PubMed1992

Geographic diversity of human immunodeficiency virus type 1: serologic reactivity to env epitopes and relationship to neutralization.

The antibody recognition of the major neutralization epitopes of human immunodeficiency virus type 1 (HIV-1) in 829 HIV-1-seropositive subjects from North America (106), Europe (241), Africa (342), and Asia (100) was investigated. Peptides derived from diverse published V3 loop sequences were used as antigen, and serum reactivity was detected by sensitive ELISAs. Antibody binding to peptides derived from the V3 loop sequence of HIV-1 isolates varies considerably depending on the geographic origin of the antibody and is associated with neutralization titer against homologous isolates. Serotype reactivity to peptides may be a simple and rapid approach to investigation of HIV-1 env diversity worldwide and may assist the choice of immunogen for development of future AIDS vaccines.

Africa↗
PubMed1991

Cutaneous hypersensitivity reactions due to thiacetazone in HIV-1 seropositive patients treated for tuberculosis.

The effects of the human immunodeficiency virus (HIV) on tuberculosis management was investigated in 227 patients initially treated with a regimen containing streptomycin, isoniazid, and thiacetazone (STH). 93 of these 227 were HIV-seropositive. 60 patients, of whom 18 were HIV-seropositive, received a regimen consisting of streptomycin, isoniazid, rifampicin, and pyrazinamide (SHRZ) in the initial phase, and thiacetazone and isoniazid (TH) in the continuation phase. Cutaneous hypersensitivity reactions occurred in 22 of 111 (20%) HIV-seropositive patients, and in 2 of 176 (1%) HIV-seronegative patients (RR = 18, 95% CI 4.4-76, p less than 10(-7]. During the first 8 weeks of treatment 18 reactions occurred among the 93 HIV-seropositive patients on STH, whereas no reaction occurred in 17 HIV-seropositive patients during the initial phase of SHRZ/TH (p = 0.04). None of the 18 HIV-seropositive patients with cutaneous reactions who were subsequently challenged with isoniazid reacted, nor did any of the 10 tested with streptomycin, but 6 of the 7 challenged with thiacetazone reacted. 3 patients (all HIV-positive and with toxic epidermal necrolysis) died as a result of the cutaneous reaction. These results have major implications for tuberculosis control programmes in Africa.

Adult↗
PubMed1991

Comparative humoral responses to HIV-1 p24gag and gp120env in subjects from East Africa and the UK.

We compared 1616 sera from HIV-1-infected subjects and matched HIV-negative local controls in Uganda, Kenya and the UK. Sera were screened for specific antibody to HIV-1 p24 Gag and gp120 Env proteins and for p24 antigenaemia. In contrast to the UK, the majority of African HIV-1-infected subjects maintained detectable anti-p24 antibodies. However, lower reactivity of anti-p24 was observed in African AIDS patients, compared with those with asymptomatic HIV-1 infection. This reduction in anti-p24 reactivity with more advanced clinical stage was less marked in African HIV-1 infection than in the UK. Correspondingly, p24 antigenaemia was more common in patients with AIDS from the UK than in African patients (65 versus 4%). Reductions in anti-gp120 reactivity were observed in African AIDS patients, compared with the asymptomatic group. However, median reactivity of anti-gp120 in UK patients remained unchanged in both asymptomatic and AIDS subjects. The differences in humoral response to p24 and gp120 between Africa and the UK are semi-quantitative rather than qualitative and could be explained by initial higher antibody response to HIV-1 in African subjects.

Cross-Sectional Studies↗
PubMedDate not supplied

Toxoplasma antibodies in HIV-positive patients from Nairobi.

Sera from 94 patients infected with human immunodeficiency virus (HIV) 1, together with 86 controls, attending the Kenyatta National Hospital, Nairobi were examined for antibodies to Toxoplasma gondii using enzyme immunoassay and latex and dye tests. 54% had Toxoplasma-specific immunoglobulin G (IgG) by dye test. 22% of the HIV-positive group had IgG levels in excess of 180 units/ml (approximating to a dye test titre of 1:1300) compared to 1% of the HIV-negative group. There was no correlation between high levels of IgG and clinical stage of HIV disease or features indicative of active toxoplasmosis. It is proposed that the elevated serum IgG is a reflection of early Toxoplasma reactivation, not necessarily associated with disease.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Serological responses to brucellosis in HIV-seropositive patients.

Serial sera from 2 patients infected with the human immunodeficiency virus (HIV) type 1 attending a clinic in Nairobi, Kenya, and with blood cultures yielding Brucella melitensis, were tested by enzyme-linked immunosorbent assay for their serological response (Brucella-specific immunoglobulin (Ig) M and IgG) to Brucella infection. Antibody responses were comparable to those of immunocompetent individuals, one patient showing serology typical of acute brucellosis, the other of chronic brucellosis. Sera from 100 other patients, 65 of whom were HIV-positive, attending the same clinic but whose routine microbiological cultures were negative for Brucella, were tested retrospectively for Brucella-specific antibody. Eight had Brucella-specific IgM and IgG, 6 had IgM only and 21 had IgG only, suggesting relatively high levels of exposure to Brucella in the study cohort. There was no association between Brucella antibody status and HIV status. Brucellosis is probably underdiagnosed in Kenya. Brucella serology may be helpful in the diagnosis of patients with non-specific symptoms in East Africa, regardless of HIV status.

Antibodies, Bacterial↗
PubMedDate not supplied

Use of clinical judgement to guide administration of blood transfusions in Malawi.

The aim of this study was to investigate whether clinicians in Malawi could use clinical judgement alone to administer blood transfusions in accordance with guidelines. Clinicians at a district hospital did not use the Lovibond Comparator haemoglobin results provided by their laboratory as they felt them to be unreliable, preferring instead to rely on their clinical judgement alone to guide transfusion practice. Their transfusion practice and the Lovibond haemoglobin results were monitored against the World Health Organization recommended haemiglobincyanide method for haemoglobin measurement without the clinicians having access to this result. The Lovibond Comparator method was shown to have a sensitivity of only 21% to detect trigger haemoglobin values for transfusion published in local guidelines. Without access to a useful haemoglobin result, clinicians gave 67% of transfusions in accordance with the haemoglobin trigger values in the guidelines. This study shows that clinical features alone can provide a reasonable guide about the need for transfusion, and that poor quality laboratory tests limit the effectiveness of transfusion guidelines.

Anemia↗
PubMedDate not supplied

Carriage of potentially pathogenic Escherichia coli in chickens.

DNA-DNA hybridization, cultured cell lines, and transmission electron microscopy were used to study pathogenicity traits of 64 Escherichia coli isolated from apparently healthy chickens from 18 small-scale farms in Thika District, Kenya. A total of 39 (60.9%) isolates hybridized with the eae gene probe for enteropathogenic E. coli (EPEC) whereas another 16 (25%) hybridized with the lt and st gene probes and were categorized as enterotoxigenic E. coli. Electron microscopic examination of the eae probe-positive E. coli cultures with the HT-2919A cell line confirmed that they were able to attach intimately and produced effacement typical of EPEC. In addition, negative stain electron microscopy showed that the EPEC strains produced pili that have previously been associated with increased virulence of E. coli infections in chickens. This study has also demonstrated that apparently healthy chickens may carry enteropathogenic E. coli strains.

Animals↗