Genetic heterogeneity and predominance of blaCTX-M -15 in cefotaxime-resistant Enterobacteriaceae isolates colonizing hospitalized children in Tunisia.

Extended-spectrum ß-lactamase (ESBL)-producing Enterobacteriaceae have emerged as important nosocomial pathogens. Community infections by these organisms have been also reported and were associated with previous intestinal colonization. We aimed to characterize cefotaxime-resistant Enterobacteriaceae (CTX-R-En) isolated from hospitalized children in a Tunisian paediatric ward. Seventy CTX-R-En isolates were collected from 227 rectal swabs from hospitalized children in a paediatric ward. Antimicrobial susceptibility testing was determined according to the EUCAST guidelines. Isolates were characterized by polymerase chain reaction (PCR, genes encoding: ESBLs, pAmpC, carbapenemases, plasmid-mediated quinolone resistance, virulence factors in Escherichia coli and Klebsiella pneumoniae isolates, occurrence of classes 1 and 2 integrons, phylogenetic groups of E. coli isolates, ERIC-PCR and PCR-based replicon typing) and conjugal transfer experiments. In total, 65 out of 227 (28·6%) hospitalized children were colonized with CTX-M-R-En, and 70 isolates were identified. Isolates were 59 ESBL-, 7 plasmidic-AmpC (pAmpC)-, 3 ESBL+pAmpC-, and one ESBL+carbapenemase producers. The following bla genes were identified: blaCTX-M-15 (n = 54), blaCTX-M-1 (n = 5), blaCTX-M-9 (n = 2), blaCTX-M-13 (n = 1) and blaCTX-M-14 (n = 1), blaCMY-2 (n = 5), blaCMY-4 (n = 4), blaACC-1 (n = 1) and blaOXA-48 (n = 1). Our results showed that hospitalized children were colonized with various CTX-R-En-producing several beta-lactamase enzymes.

Polymorphism of ftsI gene in Haemophilus influenzae and emergence of cefotaxime resistance in two Tunisian hospitals.

The decreased affinity to ß-lactams in Haemophilus influenzae is usually caused by specific alterations in penicillin-binding protein 3 due to varieties of substitutions in ftsI gene. This study aimed to characterize the polymorphism of ftsI gene in 19 H. influenzae strains, isolated between 2014 and 2016 (different resistance phenotypes to ß-lactams (n = 9) and susceptible strains (n = 10) used for comparative purposes). All strains were characterized for capsular type by PCR and agglutination tests and for ß-lactam resistance by amplification and sequencing of ftsI. Biotyping and clonality were performed by API-NH and pulsed-field gel electrophoresis, respectively. Four strains were ß-lactamase-negative ampicillin-resistant and five were ß-lactamase-positive clavulanic-acid-resistant. One strain from each group was resistant to cefotaxime. Our isolates belonged mainly to biotype IV and I and were non-typeable and genetically unrelated. According to mutation profiles of their ftsI, strains were classified as group I (n = 3), group II (n = 4), group-III-like (n = 1) and group III (n = 1). All group II strains were further classified as subgroup IIb, except for one strain, which harboured a new mutation (N422I). Ampicillin MICs of ß-lactamase-negative ampicillin-resistant strains were 6 to 12 times the MICs of susceptible strains. Only bla TEM-1 was detected in ß-lactamase-positive clavulanic-acid-resistant strains, and was responsible for high MICs for ampicillin (>256 mg/L), whatever the ftsI mutational resistance group. The emergence of cefotaxime-resistant isolates in our country is a matter of concern and requires strict surveillance and rationalization of antibiotic use to preserve these molecules.

[Risk factors for hospital mortality during pulmonary embolism]. / Facteurs de risque de mortalité hospitalière au cours de l'embolie pulmonaire en milieu de pneumologie.

OBJECTIVES: The objective of our work is to identify the risk factors for hospital mortality during pulmonary embolism in a pneumology department. MATERIAL AND METHOD: All patients admitted to the pneumology department of Habib-Bourguiba hospital between 2014 and 2019, with a final diagnosis of PE are analyzed. RESULTS: One hundred patients were included, 62% of whom were female, with an average age of 63±16 years. Pulmonary fibrosis was noted in eight patients. On admission, the mean Simplified Pulmonary Embolism Severity Index score was 1.46±1.05. The mean duration of hospitalization was 10.6±7 days. The hospital mortality rate was 12%. The independent risk factors for intra-hospital mortality were arterial hypotension (OR: 6.13; 95%CI: 2.88-14.35; p=0.001), cancer (OR: 2.66; 95%CI: 1.22-9.54; p=0.026), a VD/LV ratio at echocardiography>0.9 (OR: 1.84; 95%CI: 1.06-7.69; p=0.039) and severe hypoxemia (OR: 4.86; 95%CI: 2.19-11,34; p=0.006). CONCLUSION: Pulmonary embolism mortality remains high despite improvements in diagnostic and therapeutic management. It is important for our country to take these results into consideration for a better management of patients admitted for pulmonary embolism, and to improve survival.

A comparative study of antimicrobial resistance rates and phylogenetic groups of community-acquired versus hospital-acquired invasive Escherichia coli.

OBJECTIVES: Escherichia coli is the leading cause of various infections, both in community and nosocomial settings. Our objective was to determine the antibiotic resistance rates and the phylogenetic groups of invasive E. coli and to assess the relationship between these characteristics according to the community or nosocomial origin of the strains. MATERIALS AND METHODS: One hundred non-redundant E. coli strains, causing invasive infections, were collected and investigated between 2010 and 2012. The phylogenetic groups were determined by triplex PCR. The statistical analysis was performed with Pearson χ(2) test and P-values below 0.05 were considered as statistically significant. RESULTS: Sixty-three strains were community-acquired (CA) and 37 were hospital-acquired (HA). The resistance rates among CA and HA strains were respectively: cefotaxime (11.1/37.8%), ciprofloxacin (19/43.2%), amikacin (3.2/27.2%), and cotrimoxazole (42.8/64.8%). E. coli strains caused bacteremia (CA=34.9%; HA=83.7%), peritonitis (CA=58.7%; HA=13.5%), appendicitis (CA=3.2%; HA=2.7%), and cholecystitis (CA=3.2%; HA=0%). The distribution of phylogenetic groups among CA and HA strains was: A (25.4/18.9%), B1 (9.5/16.2%), B2 (23.8/37.8%), and D group (41.3/27%). High resistance rates to cefotaxime (P=0.02), ciprofloxacin (P=0.01), amikacin (P=0.001), and cotrimoxazole (P=0.05) were statistically significantly associated with a nosocomial origin. CONCLUSION: Our results prove the diversity of phylogroups among E. coli invasive strains whatever their origin, and a higher antibiotic resistance rate in nosocomial strains. An adequate use of antibiotics and applying strict hygiene measures would limit the transmission and selection of these bacteria in hospital as well as in community settings.

SU-E-J-30: Using Shifting Planned Dose Matrix to Evaluate Daily Dose Changes for IMRT Prostate Treatment.

PURPOSE: Summation of daily DVH from KV-cone beam CT (KV-CBCT) to obtain a composite dose volume histogram (DVH) is challenging. Directly translating the planned dose matrix according to measured daily prostate displacements provided a common reference frame for a composite DVH from daily DVHs. The purpose of this study is to evaluate the shifting planned dose matrix method compared to the dose recalculation method using daily KV-CBCT. METHODS: Six patients, who received concurrent IMRT treatment for prostate and pelvic lymph nodes with 124 daily CBCTs, were selected for this study. Contours for CBCT's were transferred from the planning CT after soft tissue registration for prostate and bony registration for pelvic lymph nodes. Using the same planning beam configurations, we re-calculated doses for these CBCTs after shifting to corrected treatment isocenters. The planned dose matrix translation was performed by an in-house program written in MATLAB and incorporated with Computational Environment for Radiotherapy Research (CERR) software. The corresponding daily DVH was obtained by shifting the planned dose matrix according to shifts of treatment iso-centers. To compare these two methods, selected endpoint doses for tumor targets and sensitive structures were extracted from DVHs. RESULTS: For prostate displacement less then 1.5 cm, the dose matrix shifting method resulted in 93% and 98% fractions within 5% differences from the recalculation method for D95 of prostate and pelvic lymph nodes, respectively. These numbers decreased to 58% and 71% when 2% dose difference criterion was used. CONCLUSIONS: Allowing 5% daily dose difference, shifting planned dose matrix provides effective means to evaluating daily dose changes for concurrent IMRT treatment for prostate and pelvic lymph nodes. The utility of this tool is to provide a common coordinate frame to obtain composite dose distributions.

Virulence determinants, phylogenetic groups and fluoroquinolone resistance in Escherichia coli isolated from cystitis and pyelonephritis.

AIM OF THE STUDY: The aim of this study is to assess the relation between virulence genotype, phylogenetic group and susceptibility to fluoroquinolones and the urinary tract infection type including pyelonephritis and cystitis due to Escherichia coli. MATERIALS AND METHODS: Between 2006 and 2007, 129 non-duplicate E. coli isolates from pyelonephritis (n=56) and cystitis (n=73) were prospectively collected. The antibiotic susceptibility was done by disk diffusion method. The phylogenetic groups, A, B1, B2 and D and 18 virulence genes were determined by multiplex PCR. Statistical analysis was done with the Pearson χ2 test, Mann-Whitney U-test, Kruskal-Wallis test and stepwise multivariable logistic regression analysis, P values below 0.05 were considered statistically significant. RESULTS: For the pyelonephritis group, sex ratio was 0.3, the median age for women was 30 years and for men it was 54 years. For the cystitis group, sex ratio was 0.4, the median age for women was 41.5 years and for men it was 67.8 years. Significant statistical correlations were found between pyelonephritis isolates and susceptibility to ciprofloxacin (P=4 10(-5)), papG allele II (P=2 10(-6)), hlyA (P=10(-03)), iroN (P=0.04), iha (P=0.03) and ompT (P=0.03) virulence genes, high virulence score (P=0.008) and B2 phylogenetic group (P=0.03). In multivariate logistic regression analysis, papG II as predictor of pyelonephritis, no correlation could be established for the cystitis group. CONCLUSION: Our findings argue for a direct link between pyelonephritis, virulence factors, susceptibility to fluroquinolones and B2 phylogenetic group among uropthogenic E. coli.

Thermo-recurrent nematic random laser.

This experimental work is aimed to investigate the thermal behavior of random laser action in dye doped nematic liquid crystals. The study evidenced an important temperature dependence of the random lasing characteristics in the nematic phase and in close proximity of the nematicisotropic (N-I) phase transition. A lowering of the laser emission intensity as the temperature increases is strictly related to the shift of the lasing threshold as function of the temperature even though the pump energy is kept fixed. The optical losses increasing owing to the thermal fluctuation enhanced scattering drive the input-output smoother behavior until the system stops to lase, because below threshold. The unexpected reoccurrence of random lasing at higher temperature, in proximity of N-I transition is found to be related to a different scattering mechanism, the micro-droplets nucleation and critical opalescence.

Random lasing and weak localization of light in dye-doped nematic liquid crystals.

The first observation of random laser action in a partially ordered, optically anisotropic nematic liquid crystal with long-range dielectric tensor fluctuations is reported. Above a given pump power the fluorescence curve collapses and the typical narrowing and explosion effect leads to discrete sharp peaks. The unexpected surviving of interference effects in recurrent multiple scattering provide the required optical feedback for lasing in nematics. Coherent backscattering of light waves in orientationally ordered nematic liquid crystals manifests a weak localization of light which strongly supports diffusive laser action in presence of gain medium. Intensity fluctuations of the speckle-like emission pattern indicate the typical spatio-temporal randomness of diffusive laser emission. A comparison of the laser action is reported for systems with different order degree: fully disordered semiconductor powders, self-ordered cholesterics and partially ordered nematic liquid crystals.