BackgroundDrug-resistant tuberculosis (TB) is a global public health problem. Adequate management requires baseline drug-resistance prevalence data. In West Africa, due to a poor laboratory infrastructure and inadequate capacity, such data are scarce. Therefore, the true extent of drug-resistant TB was hitherto undetermined. In 2008, a new research network, the West African Network of Excellence for Tuberculosis, AIDS and Malaria (WANETAM), was founded, comprising nine study sites from eight West African countries (Burkina Faso, The Gambia, Ghana, Guinea-Bissau, Mali, Nigeria, Senegal and Togo). The goal was to establish Good Clinical Laboratory Practice (GCLP) principles and build capacity in standardised smear microscopy and mycobacterial culture across partnering laboratories to generate the first comprehensive West African drug-resistance data.MethodsFollowing GCLP and laboratory training sessions, TB isolates were collected at sentinel referral sites between 2009–2013 and tested for first- and second-line drug resistance.ResultsFrom the analysis of 974 isolates, an unexpectedly high prevalence of multi-drug-resistant (MDR) strains was found in new (6 %) and retreatment patients (35 %) across all sentinel sites, with the highest prevalence amongst retreatment patients in Bamako, Mali (59 %) and the two Nigerian sites in Ibadan and Lagos (39 % and 66 %). In Lagos, MDR is already spreading actively amongst 32 % of new patients. Pre-extensively drug-resistant (pre-XDR) isolates are present in all sites, with Ghana showing the highest proportion (35 % of MDR). In Ghana and Togo, pre-XDR isolates are circulating amongst new patients.ConclusionsWest African drug-resistance prevalence poses a previously underestimated, yet serious public health threat, and our estimates obtained differ significantly from previous World Health Organisation (WHO) estimates. Therefore, our data are reshaping current concepts and are essential in informing WHO and public health strategists to implement urgently needed surveillance and control interventions in West Africa.

Extended spectrum β-lactamase (ESBL) and carbapenemase-producing Enterobacteriaceae (CPE) have been increasingly reported worldwide. The objective of this study is to determine the prevalence of these multidrug-resistant strains in a major university teaching hospital in Dakar, Senegal. A total of 1205 Enterobacteriaceae stains were tested for ESBL and carbapenemase production. Antibiotics susceptibility test was performed with disk diffusion method. ESBL was detected using a double-disk synergy method. Carbapenemase production was detected with ertapenem 10 µg disk charge. The overall prevalence of ESBL-and carbapenemase-producing Enterobacteriaceae was 26.2 (316/1205) and 5.1% (62/1205), respectively. Interestingly, 3.8% of these pathogens were both ESBL-carbapenemase producers. Among the Enterobacteriaceae ESBL positive, Escherichia coli (45.2%, 143/316), Klebsiella pneumoniae (26.3%, 83/316), Enterobacter cloacae (12.7%, 40/316), and Proteus vulgaris (9.2%, 29/316) were the most prevalent. These strains were mainly isolated from urine (56.6%) and pus (22.7%) specimen. The most prevalent CPEs were E. coli (45.2%, 28/62), K. pneumoniae (27.4%, 17/62), and E. cloacae (16.1%, 10/62), particularly isolated from urine (58%) and pus (19.3%). The majority of these MDR strains were isolated from patients hospitalized in urology (32.4%), surgery (27.7%), internal medicine (18.5%), and intensive care units (10%). ESBL-producing Enterobacteriaceae remain highly susceptible to fosfomycin (94.1%), amikacin (92.5%) and ertapenem (88.6%), while carbapenemase producers were fully susceptible to amikacin (100%), and to a lesser extent, fosfomycin (66.7%) and colistin (60%). This study revealed increasing prevalence of ESBL-and carbapenemase-producing Enterobacteriaceae with limited therapeutic options, suggesting a need for continuous multi-drug resistant (MDR) surveillance patterns particularly in hospital settings.

Background Bacterial virulence is a key factor determining the outcome of each bacterial infection and virulent bacteria are often associated to high-risk infections. Extraintestinal pathogenic Escherichia coli (ExPEC) is the most implicated bacterium in human bacterial infections and its virulence factors are classified into five categories: adhesins, toxins, iron capture systems, protectins and invasins. Furthermore, bacterial biofilms are the main cause of hospital-acquired infections like urinary catheter-associated infections, valve endocarditis, Otitis and cystic fibrosis.Results For the sixteen virulence genes sought by standard polymerase chain reaction (PCR), all the 78 ExPECs isolates carried at least four virulence genes. Following prevalences of virulence genes were reported: adhesins genes fimH (98.7%), mrkD (98.7%), papC (46.2%), afaC (9%), sfa / focDE (1.3%); iron acquisition systems genes entB (98.7%), fepA (98.7%), ybtS (93.6%), fyuA (91%), iucA (91%), iucB (91%), iutA (34.6), iroB (6.4%), iroN (6.4%) and toxins genes hlyA (10.3%), cnf (1 & 2) (10.3%). Seventy-five out of 78 isolates (96.2%) carried at least the combination of two adhesins genes and two iron capture systems genes whereas 8 out of 78 (10.3%) harbored the combination of (adhesins genes + iron acquisition systems genes + toxins genes). Among the 78 strains studied, one hospital-acquired strain isolated from urine harbored 15 virulence genes out of 16 sought. The evaluation of biofilm-formation capacity revealed that all (29/29) hospital-acquired isolates were biofilm producers with (6/29; 20.7%) strong biofilm producers, (15/29; 51.7%) moderate biofilm producers and (8/29; 27.6%) weak biofilm producers. Isolates carrying papC had greater biofilm formation capacity than those not carrying papC (p < 0.001).Conclusions Most of our strains had moderate biofilm-formation capacity and carried an average of 9 virulence genes out of 16 sought. These eight strains carrying a combination of genes (adhesins + iron acquisition systems genes + toxins genes) may be hypervirulent isolates. Additional studies may confirm this. The deepening of this kind of study on bacterial virulence and hospital bacterial biofilms could lead to the improvement of infections investigation, prevention and therapeutic protocols.

Enterobactericeae producing extended spectrum -lactamases (ESBL) are likely to express carbapenemases OXA-48 which have hydrolytic activity on carbapenems. The aim of this work was to evaluate prevalence of blaOXA-48 for Klebsiella pneumoniae isolates producing ESBL. This work was conducted at the French Reference Center for Antibiotic Resistance with strains from Senegalese Hospital. Standard antibiogram was performed in accordance to CA-SFM/EUCAST 2016 and presence of ESBL was confirmed by synergistic image. Polymerase chain reaction (PCR) was performed to detect systematically blaOXA-1, blaTEM-1, blaCTX-M-1, blaCTX-M-9 and blaOXA-48 gene in case of decrease sensitivity to carbapenem. PCR products were extracted, purified, sequenced and whole-genome sequence (WGS) were used for the analyses. Plasmids extraction was performed by Kado and Liu method. Five isolates harbored a decreased susceptibility to carbapenems. They were positive for blaOXA-48 gene and also expressed blaCTX-M-15. Analysis of the five plasmids by WGS identified a single IncL/M type plasmid of 63 kb and other genes for aminoglycosides and quinolones resistance. Carbapenemase-producing Enterobacteriaceae represent new threat to public health. Decrease in carbapenem susceptibility should be an alert for rapid detection of carbapenemases and to prevent their spread. Phenotypic or molecular methods should be available in many laboratories to take appropriate preventive and therapeutic measures.