[Phenotypic and genotypic characteristics of non fermenting atypical strains recovered from cystic fibrosis patients]

Healthcare-associated infections: bacteriological characterization of the hospital surfaces in the University Hospital of Abomey-Calavi/so-ava in South Benin (West Africa)

Background

Healthcare-associated infections have become a public health problem, creating a new burden on medical care in hospitals. The emergence of multidrug-resistant bacteria poses a difficult task for physicians, who have limited therapeutic options. The dissemination of pathogens depends on “reservoirs”, the different transmission pathways of the infectious agents and the factors favouring them. Contaminated environmental surfaces are an important potential reservoir for the transmission of many healthcare-associated pathogens. Pathogens can survive or persist in the environment for months and be a source of infection transmission when appropriate hygiene and disinfection procedures are inefficient. The aim of this study was to identify bacterial species from hospital surfaces in order to effectively prevent healthcare-associated infections.

Methods

Samples were taken from surfaces at the University Hospital of Abomey-Calavi/So-Ava in South Benin (West Africa). To achieve the objective of this study, 160 swab samples of hospital surfaces were taken as recommended by the International Organization for Standardization (ISO 14698-1). These samples were analysed in the bacteriology section of the National Laboratory for Biomedical Analysis. All statistical analyses were performed using SPSS Statistics 21 software. A Chi Square Test was used to test the association between the Results of culture samples and different care units.

Results

Of the 160 surface samples, 65% were positive for bacteria. The frequency of isolation was predominant in Paediatrics (87.5%). The positive samples were 64.2% Gram-positive bacteria and 35.8% of Gram-negative bacteria. Staphylococcus aureus predominated (27.3%), followed by Bacillus spp. (23.3%).

The proportion of other microorganisms was negligible. S. aureus and Staphylococcus spp. were present in all care units. There was a statistically significant association between the Results of culture samples and different care units (χ2 = 12.732; p = 0.048).

Conclusion

The bacteria found on the surfaces of the University Hospital of Abomey-Calavi/So-Ava’s care environment suggest a risk of healthcare-associated infections. Adequate hospital hygiene measures are required. Patient safety in this environment must become a training priority for all caregivers.

Proposal of a quantitative PCR-based protocol for an optimal Pseudomonas aeruginosa detection in patients with cystic fibrosis

Background

The lung of patients with cystic fibrosis (CF) is particularly sensitive to Pseudomonas aeruginosa. This bacterium plays an important role in the poor outcome of CF patients. During the disease progress, first acquisition of P. aeruginosa is the key-step in the management of CF patients. Quantitative PCR (qPCR) offers an opportunity to detect earlier the first acquisition of P. aeruginosa by CF patients. Given the lack of a validated protocol, our goal was to find an optimal molecular protocol for detection of P. aeruginosa in CF patients.

Methods

We compared two formerly described qPCR formats in early detection of P. aeruginosa in CF sputum samples: a qPCR targeting oprL gene, and a multiplex PCR targeting gyrB and ecfX genes.

Results

Tested in vitro on a large panel of P. aeruginosa isolates and others gram-negative bacilli, oprL qPCR exhibited a better sensitivity (threshold of 10 CFU/mL versus 730 CFU/mL), whereas the gyrB/ecfX qPCR exhibited a better specificity (90% versus 73%). These results were validated ex vivo on 46 CF sputum samples positive for P. aeruginosa in culture. Ex vivo assays revealed that qPCR detected 100 times more bacterial cells than culture-based method did.

Conclusion

Based on these results, we proposed a reference molecular protocol combining the two qPCRs, which offers a sensitivity of 100% with a threshold of 10 CFU/mL and a specificity of 100%. This combined qPCR-based protocol can be adapted and used for other future prospective studies.

Detection and accurate identification of new or emerging bacteria in cystic fibrosis patients

Respiratory infections remain a major threat to cystic fibrosis (CF) patients. The detection and correct identification of the bacteria implicated in these infections is critical for the therapeutic management of patients. The traditional methods of culture and phenotypic identification of bacteria lack both sensitivity and specificity because many bacteria can be missed and/or misidentified. Molecular analyses have recently emerged as useful means to resolve these problems, including molecular methods for accurate identification or detection of bacteria and molecular methods for evaluation of microbial diversity. These recent molecular technologies have increased the list of new and/or emerging pathogens and epidemic strains associated with CF patients. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of intact cells has also emerged recently as a powerful and rapid method for the routine identification of bacteria in clinical microbiology laboratories and will certainly represent the method of choice also for the routine identification of bacteria in the context of CF. Finally, recent data derived from molecular culture-independent analyses indicate the presence of a previously underestimated, complex microbial community in sputa from CF patients. Interestingly, full genome sequencing of some bacteria frequently recovered from CF patients has highlighted the fact that the lungs of CF patients are hotspots for lateral gene transfer and the adaptation of these ecosystems to a specific chronic condition.