B. I. F. Batchelor

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.

Disseminated mycobacterium avium Infection Among Hiv-infected Patients in Kenya

Previous studies from Africa have been unable to identify disseminated Mycobacterium avium complex (MAC) infection in patients with advanced human immunodeficiency virus (HIV) infection. We performed mycobacterial blood cultures and CD4 counts on 48 symptomatic adults with advanced HIV infection admitted to the hospital in Nairobi, Kenya over 4 weeks in 1992. Fourteen patients had mycobacteremia; these patients had significantly lower CD4 counts than the patients with negative cultures (14/mm3 vs. 85/mm3; p < 0.01). Three patients (6%) were bacteremic with M. avium (mean CD4 count, 10/mm3) and 11 (23%) were bacteremic with Mycobacterium tuberculosis complex (MTB) (mean CD4 count, 15/mm3). Thus, M. avium bacteremia was detected significantly less frequently in the study population than MTB bacteremia (p = 0.04). The minimum rate for HIV-associated disseminated M. avium infection in patients admitted to the hospital in Nairobi was estimated to be approximately 1%. Patients with mycobacteremia died or were discharged home sick before the diagnosis was made. Disseminated M. avium does occur in adults with advanced HIV infection in sub-Saharan Africa, but is less common than disseminated MTB.

Biochemical mis-identification of Brucella melitensis and subsequent laboratory-acquired infections

Brucella species are mis-identified in the API 20NE system as Moraxella phenylpyruvica (profile number 1200004). Since some Brucella spp. grow readily in routine blood culture medium and may be isolated from patients without clinically obvious brucellosis, the risk of laboratory-acquired brucellosis exists. We describe two such cases.

Recent transmission of tuberculosis in a cohort of HIV-1-infected female sex workers in Nairobi, Kenya

Objectives: To describe the epidemiological and clinical characteristics of HIV‐related tuberculosis in a female cohort, and to investigate the relative importance of recently transmitted infection and reactivation in the pathogenesis of adult HIV‐related tuberculosis. Design: Members of an established cohort of female sex workers in Nairobi were enrolled in a prospective study. Women were followed up regularly and seen on demand when sick. Methods: Between October 1989 and September 1992 we followed 587 HIV‐infected and 132 HIV‐seronegative women. Standard protocols were used to investigate common presentations. Cases of tuberculosis were identified clinically or by culture. All available Mycobacterium tuberculosis strains underwent DNA fingerprint analysis. Results: Forty‐nine incident and four recurrent episodes of tuberculosis were seen in HIV‐infected women; no disease was seen in seronegative sex workers (P = 0.0003). The overall incidence rate of tuberculosis was 34.5 per 1000 person‐years amongst HIV‐infected participants. In purified protein derivative (PPD) skin test‐positive women the rate was 66.7 per 1000 person‐years versus 18.1 per 1000 person‐years in PPD‐negative women. Twenty incident cases (41%) were clinically compatible with primary disease. DNA fingerprint analysis of strains from 32 incident cases identified two clusters comprising two and nine patients; allowing for index cases, 10 patients (28%) may have had recently transmitted disease. Three out of 10 (30%) patients who were initially PPD skin test‐negative became PPD‐positive. Taken together, 26 incident cases (53%) may have been recently infected. DNA fingerprint analysis also identified two (50%) of the four recurrent tuberculosis episodes as reinfection. Conclusions: Substantial recent transmission of tuberculosis appears to be occurring in Nairobi amongst HIV‐infected sex workers. It may be incorrect to assume in other regions of high tuberculosis transmission that active HIV‐related tuberculosis usually represents reactivation of latent infection.

Nasopharyngeal Carriage of Staphylococcus-Aureus and Carriage of Tetracycline-Resistant Strains Associated with Hiv-Seropositivity

The aim of this prospective study was to investigate the relationship between carriage of antibiotic-resistantStaphylococcus aureus and infection with the human immunodeficiency virus (HIV). A total of 554 pernasal swabs was taken during a six-month period from 554 adult patients attending three outpatient clinics and from inpatients from a hospital in Nairobi, Kenya. Overall, 121 swabs (22 %) yieldedStaphylococcus aureus, there being significantly higher carriage in HIV-positive patients (71/264, 27 %) than in HIV-negative patients (50/290, 17 %); p=0.008. Antimicrobial resistance rates were determined for 110 isolates and were high for penicillin (91 %) and tetracycline (72 %) and low for erythromycin (8 %), methicillin (3 %), gentamicin (5 %) and chloramphenicol (0 %). Genetic analysis showed plasmids in the range of 24–42 MDa to be associated with β-lactamase production and plasmids in the range of 3–5 MDa to be associated with resistance to tetracycline, erythromycin and trimethoprim. All nine erythromycin-resistant strains were from HIV-positive patients (p=0.02). There was a significant association of tetracycline resistance with HIV seropositivity (p=0.002). The association of HIV seropositivity withStaphylococcus aureus carriage and carriage of antibiotic-resistant strains against the background of the HIV epidemic are of relevance in individual patient care and raise concern for public health.

Bacteriuria in a cohort of predominantly HIV-1 seropositive female commercial sex workers in Nairobi, Kenya

Although significant bacteriuria and urinary tract infection are more common in immunocompetent women than men, studies linking HIV immunosuppression with an increased risk of developing urinary infection have so far only been carried out in men. We therefore examined the relationship between bacteriuria and HIV status and CD4+cell count in a relatively homogeneous cohort of female commercial sex workers (CSW) attending a community clinic in Nairobi. Two hundred and twenty-two women were enrolled, and grouped according to HIV status and CD4 count. Group 1 were HIV seronegative (n = 52); Group 2 were HIV seropositive with CD4 + counts above 500 x 10(6)/l (n = 51); Group 3 were HIV seropositive with CD4 + counts between 201 and 500 x 10(6)/l (n = 67); Group 4 were HIV seropositive with CD4+counts below 200 x 10(6)/l (n = 52). Clinical signs and symptoms were noted and mid-stream specimens of urine obtained for culture and sensitivity. Overall 23% (50/222) had significant bacteriuria. The rates in each group respectively were 25%, 29%, 19% and 23% and there was no significant association between bacteriuria and HIV status; or between bacteriuria and level of immuno-suppression as indicated by CD4 + count. Overall 19% (30/222) of women had symptoms (frequency; dysuria; loin pain; smelly urine) or signs (fever; loin tenderness) compatible with urinary tract infection. However there was no significant association between symptoms or signs of infection and bacteriuria or HIV status. A typical range of pathogens, predominantly Enterobacteriaceae, were isolated and there were high rates of resistance to commonly used antimicrobials as well as 10% resistance to ciprofloxacin. Although high rates of significant bacteriuria can occur in highly sexually-active women, this appears unrelated to HIV infection or the level of HIV-related immunosuppression and is generally asymptomatic or clinically indistinct.

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.

Microbiology of HIV associated bacteraemia and diarrhoea in adults from Nairobi, Kenya

We undertook a retrospective descriptive comparison of the spectrum of pathogens responsible for bacteraemia and diarrhoea in HIV antibody positive and negative patients over 4 years (1988-92), in Nairobi, Kenya. The study population was recruited from primary to tertiary centres of clinical care and consisted of 2858 adults (15 years or older). There were 415 significant blood culture isolates, 192 from 1785 HIV negative patients and 223 from 953 HIV positive patients. There were 233 significant faecal isolates, 22 from 115 HIV negative patients and 211 from 531 HIV positive patients. The most common pathogens detected in blood were Streptococcus pneumoniae and Salmonella typhimurium and in faeces Shigella flexneri, S. typhimurium and Cryptosporidium parvum. The agents causing illness in HIV positive patients in Nairobi are similar to those prevalent in the HIV negative community and the investigation of a febrile illness with or without diarrhoea in an HIV positive patient should reflect this.