Stability of blood potassium: effects of duration, temperature and transport during 10 hours storage of human whole blood in serum and plasma.

To comply with the pre-analytical requirements of ISO EN 15189, we investigated the stability of potassium, a very critical and sensitive analyte. We took into count effects of duration, temperature and transport after 10 hours storage of human whole blood in serum and plasma. Blood of 12 healthy subjects was analyzed after 4, 6, 8 and 10 hours of storage. Three study groups were designed: samples stored in laboratory at room temperature, transported by car during 4 hours at a temperature of 21±1̊C, with or without previous thermal shock (20 min at 4±1 ÌŠC) before transportation. Variations in concentration were expressed as mean bias from baseline using the analytical change limit (ACL) and the reference change value (RCV). Using RCV, we considered that potassium was biologically stable during 10 hours whatever our study groups. Considering ACL, potassium in serum was not stable after the thermal shock. We conclude that whole blood in lithium-heparin tubes may be used for routine potassium analysis even if long car transportation and previous thermal shock is involved. It confirms that potassium analysis can be still performed in locations distant from a medical laboratory.

Analysis of topoisomerase mutations in fluoroquinolone-resistant and -susceptible Campylobacter jejuni strains isolated in Senegal.

In this study, topoisomerase mutations in ciprofloxacin-resistant and -susceptible Campylobacter jejuni were analysed by DNA sequencing. In certain ciprofloxacin-resistant C. jejuni, the mechanism of resistance was complex. The Thr86-Ala substitution in the GyrA protein appears to play a role in increasing the minimum inhibitory concentration of nalidixic acid only. In addition, isolates with this amino acid change and those resistant to quinolones but lacking a mutation in the GyrA quinolone resistance-determining region could be derived from two different clones. Based on gyrA and gyrB polymorphisms, C. jejuni isolates from the Dakar region of Senegal appeared to be less diverse than those from other countries. Moreover, C. jejuni isolates in Senegal appeared to differ from European isolates by lack of a silent mutation at codon 120 of the gyrA gene.

In vitro susceptibility of quinolone-resistant Enterobacteriaceae uropathogens to fosfomycin trometamol, in Dakar, Senegal.

We conducted a study in order to confirm the eligibility of fosfomycin trometamol as an alternative treatment to quinolones for urinary tract infections. Among 102 quinolone-resistant Enterobacteriaceae strains, resistance rates to first line-prescribed antibiotics were above 77%. The resistance rate to fosfomycin was 2%.

Risk factors for antibiotic-resistant Escherichia coli isolated from community-acquired urinary tract infections in Dakar, Senegal.

OBJECTIVES: To assess overall resistance rates and risk factors for resistance to ampicillin, co-amoxiclav, nalidixic acid, fluoroquinolones and trimethoprim/sulfamethoxazole in Escherichia coli strains isolated from outpatients with acute urinary tract infection in Dakar (Senegal). PATIENTS AND METHODS: From June 2001 to June 2003, a prospective study was performed among Senegalese outpatients consulting at the Institut Pasteur of Dakar for urine analysis. Evaluated risk factors were: age, gender, prior hospitalization, antibiotic exposure, urinary tract infection and urinary catheter. RESULTS: A total of 398 non-duplicate, consecutive, biologically significant E. coli were isolated. The levels of antibiotic resistance in Dakar appeared dramatic and worrisome with resistance rates ranging from 18.6% for fluoroquinolones to 73.6% for ampicillin. With the exception of the presence of urinary catheter, the risk factors identified were consistent with data previously reported in developed countries. CONCLUSIONS: We hope our results will assist medical authorities in the development of appropriate control strategies.

Performance evaluation of automated depolarization analysis for detecting clinically unsuspected malaria in endemic countries.

This prospective study evaluated the efficiency of automated depolarization analysis for recognition of unsuspected malaria by haemozoin detection during routine full blood count (FBC) screening of 676 randomly selected out-patients in a malaria hypoendemic area of Senegal. An additional 123 patients with clinically suspected malaria were studied for comparison. Of the 799 samples, 648 (81.1%) were categorized as malaria-negative, 83 (10.4%) as malaria-positive, and 68 as treated (early convalescence) or subclinical malaria (indirect evidence of infection). At a discrimination level of one or more atypical pigment-containing monocytes (PCM), negative and positive agreement was found to be 95.6% and 91.6% respectively for all malaria-negative and parasite-positive samples combined. Increasing the discriminator to two or more PCM events improved the overall agreement to 97.5%. Multivariate analysis showed that the only significant risk factor for the presence of PCM (odds ratio>200) was malaria infection. In the randomly selected group of 676 patients, 41 unsuspected cases of malaria infection were detected using the panel of reference diagnostic tests, and 37 (90.2%) of these had atypical PCM. The detection of clinically unrecognized malaria infection as part of a routine FBC procedure is a potentially useful extended application for laboratories in countries with endemic malaria.

Increasing prevalence of antimicrobial resistance among Enterobacteriaceae uropathogens in Dakar, Senegal: a multicenter study.

To assess antibiotic susceptibility among Enterobacteriaceae isolated in urine from outpatients in Dakar, Senegal, a prospective multicenter study involving 3 laboratories had been conducted between June and October 2001. During this period, 300 strains were isolated and susceptibility testing was performed against antibiotics commonly used in treatment of community-acquired urinary tract infections (UTI). E. coli and K. pneumoniae represented 89% of isolates. The overall resistance rates of ampicillin, amoxicillin-clavulanic acid, nalidixic acid, fluoroquinolones and cotrimoxazole were respectively 77.3%, 34.7%, 14.7%, 13.3%, and 55%. In the light of these results, a re-evaluation of first line therapies and prudent use of fluoroquinolones is advised. At the same time a continued surveillance of antimicrobial resistance should be developed in Senegal in order to control the emergence of multidrug resistant strains and to establish a national therapeutic guideline for treatment of UTI.

Fluoroquinolone susceptibility of Campylobacter strains, Senegal.

To assess fluoroquinolone susceptibility of Campylobacter strains in Senegal, skin samples were collected from 250 chicken carcasses from January 2001 to October 2002. Among 205 isolated Campylobacter strains, 59% and 41% were identified as Campylobacter jejuni and C. coli, respectively; the overall ciprofloxacin-resistance rate was 34%.

Chromobacterium violaceum: a case of diarrhea in Senegal.

A 5-year-old infant with diarrhea had heavy growth of Chromobacterium violaceum cultured from stool. This organism is restricted geographically between latitudes 35 degrees N and 35 degrees S. It can cause sepsis and various focal infections but is not a well-known cause of diarrhea.