Clinical presentation among HIV-infected and non-infected adults with community acquired pneumonia in Nairobi.

SETTING: Risk factors for mortality in hospitalized patients with community-acquired pneumonia (CAP) are well known. There are limited data on prognostic indicators among out-patients. OBJECTIVE: To compare the clinical presentation, outcome and prognostic factors for clinical improvement in human immunodeficiency virus (HIV) infected and non-HIV-infected out-patients with CAP. METHODOLOGY: Adults in Nairobi with CAP were treated with erythromycin as first-line therapy. Clinical symptoms were evaluated using a validated CAP-related symptom score (CSS). Clinical improvement was defined as reduction of baseline CSS by > or = 50%. RESULTS: Of 531 adults enrolled with CAP, 422 (79.5%) completed follow-up. Participants had a mean age (+/- SD) of 33.7 +/- 11.4 years, 274 (51.6%) were male and 193 (37%) were HIV-seropositive with a higher baseline CSS (27 vs. 25, P < 0.006). Overall, 196 of 422 (46%) had clinical improvement by 28 days. Factors independently associated with a longer time to clinical improvement included not being married (adjusted hazard ratio [aHR] 0.66, 95% CI 0.48-0.92) and higher baseline CSS (aHR 1.05, 95% CI 1.03-1.06). CONCLUSIONS: HIV-infected and non-infected patients with CAP responded similarly to out-patient treatment, but HIV-infected patients were more likely to present with severe symptoms. Baseline CSS and marital status were predictive of time to clinical improvement.

Antimicrobial susceptibility in community-acquired bacterial pneumonia in adults.

OBJECTIVES: To determine the antimicrobial susceptibility patterns of Streptococcus pneumoniae and Haemophilus influenzae, two bacterial pathogens commonly associated with community-acquired pneumonia. DESIGN: Cross-sectional study. SETTING: Bacterial isolates were obtained from adults suspected to have community-acquired pneumonia and who sought treatment at two city council clinics in Nairobi, Kenya. Susceptibility to antimicrobial agents was performed using a microdilution broth method, according to the criteria set by the National Committee for Clinical Laboratory Standards. RESULTS: A total of 277 S. pneumoniae and 58 H. influenzae were obtained from 536 adults examined in the period January 1998 to December 1999. Of the 277 S. pneumoniae, only 56.7% were susceptible to penicillin and 7.6% of strains were resistant to two or more antimicrobial agents. Of the 58 H. influenzae strains, 91.4% were sensitive to ampicillin, with 6.8% resistant to two or more antimicrobial agents. 8.6% were beta-lactamase producers and accounted for the entire ampicillin-resistant population. CONCLUSION: The prevalence of resistance to penicillin and other commonly used antibiotics among pneumococci is high and the large number of multi-resistant strains among H. influenzae is a cause for concern. The prudent use of antibiotics in treatment of pneumonia and other infections should be advocated to minimise spread of resistance.

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.

Genotypes of multidrug-resistant Salmonella enterica serotype typhimurium from two regions of Kenya.

A combination of phage typing and pulsed-field gel electrophoresis of Xbal-digested chromosomal DNA has been used to study the epidemiological relationships of multidrug-resistant Salmonella enterica serotype typhimurium from Nairobi (64 isolates) and Kilifi (40 isolates) collected over the period 1994-1997. Isolates from Nairobi belonged to 11 definitive phage types (DTs) encompassing eight different PFGE patterns. In contrast, isolates from Kilifi were mainly DT 56 (60%) and all fell into a single PFGE pattern. The remaining isolates did not conform to a recognisable phage type. We conclude that multidrug-resistant S. typhimurium infections from Nairobi were caused by multiple strains while those from Kilifi were likely to be from a microepidemic caused by a single clone.

Analysis of Salmonella enterica serotype Typhimurium by phage typing, antimicrobial susceptibility and pulsed-field gel electrophoresis.

Three typing methods commonly used for bacteria--phage typing, antimicrobial susceptibility and pulsed-field gel electrophoresis (PFGE)- were used to characterise 64 Salmonella enterica serotype Typhimurium isolates from individual adult patients from Nairobi, Kenya. The isolates encompassed 11 definitive phage types (DTs), which fell into eight PFGE clusters; 31.3% of isolates were either untypable or reacted nonspecifically with the phages used for typing and 26.6% were of DT 56. Plasmids of c. 100 kb were responsible for self-transferable multiresistance among the isolates. Analysis by PFGE and phage type demonstrated that multiresistant Typhimurium strains causing diarrhoea and invasive disease were multiclonal.

Genotype analysis of Escherichia coli strains isolated from children and chickens living in close contact.

Escherichia coli isolates from rectal swabs from 62 chickens and stools from 42 children living in close contact with chickens on the same farms in Kiambu district, Kenya, were compared for their genetic relatedness. Antibiotic susceptibility profiles broadly categorized isolates from the children and from the chickens into two separate clusters: the majority (144; 85.5%) of the E. coli isolates from children were multidrug resistant, while the majority (216; 87.1%) of the E. coli isolates from chickens were either fully susceptible or resistant only to tetracycline. Sixty- and 100- to 110-MDA plasmids were found to encode the transferable resistance to co-trimoxazole and tetracycline. HindIII restriction endonuclease digestion of the 60- and 100- to 110-MDA plasmids produced four distinct patterns for isolates from children and three distinct patterns for isolates from chickens. XbaI digestion of genomic DNA followed by pulsed-field gel electrophoresis (PFGE) analysis produced 14 distinct clusters. There were six distinct PFGE clusters among the isolates from children, while among the isolates from chickens there were seven distinct clusters. Only one PFGE cluster contained isolates from both children and chickens, with the isolates displaying an approximately 60% coefficient of similarity. This study showed that although several different genotypes of E. coli were isolated from children and chickens from the same farms, the E. coli strains from these two sources were distinct.

Plasmid diversity of multi-drug-resistant Escherichia coli isolated from children with diarrhoea in a poultry-farming area in Kenya.

Biotin-labelled DNA probes and restriction-endonuclease digestion (RED) with HindIII were used to study the diversity of resistance plasmids (R-plasmids) from 414 Escherichia coli isolates: 168 from children living in close contact with antibiotic-fed poultry and 246 from the chickens. Full sensitivity to all 10 antimicrobials tested was more common in the isolates from poultry than in those from the children (36.2% v. 9.5%; P < 0.001). Multi-drug resistance, to at least two of the antimicrobials, was relatively common in the isolates from the children (85.5% v. 26.00%; P < 0.001). Overall, 31% of the poultry isolates were resistant to tetracycline alone. Resistance to amoxycillin was due to production of TEM-1 (89%) and TEM-2 (11%). In > 71% of the isolates from children and 79% of those from poultry, resistance was encoded on a 100-110-kb transferable plasmid belonging to incompatibility group FII. However, RED patterns of R-plasmids from the two groups of isolates were highly diverse and not indicative of any close relatedness. This difference in patterns and in the levels of multi-drug resistance indicate that the isolates from the children and those from the poultry represent two distinct pools of resistance plasmids.