Phenotypic and molecular genetic analysis of Pyruvate Kinase deficiency in a Tunisian family

Pyruvate Kinase (PK) deficiency is the most frequent red cell enzymatic defect responsible for hereditary non-spherocytic hemolytic anemia. The disease has been studied in several ethnic groups. However, it is yet an unknown pathology in Tunisia. We report here, the phenotypic and molecular investigation of PK deficiency in a Tunisian family. This study was carried out on two Tunisian brothers and members of their family. Hematological, biochemical analysis and erythrocyte PK activity were performed. The molecular characterization was carried out by gene sequencing technique. The first patient died few hours after birth by hydrops fetalis, the second one presented with neonatal jaundice and severe anemia necessitating urgent blood transfusion. This severe clinical picture is the result of a homozygous mutation of PKLR gene at exon 8 (c.1079G>A; p.Cys360Tyr). Certainly, this research allowed us to correlate the clinical phenotype severity with the identified mutation. Moreover, this will help in understanding the etiology of unknown anemia in our country

Antimicrobial drug resistance and genetic properties of Salmonella enterica serotype Enteritidis circulating in chicken farms in Tunisia

This study focused on 77 isolates of Salmonella enterica serotype Enteritidis collected during 2009 to 2013 from healthy and sick chickens and environmental farm samples in Tunisia. Resistance to 14 antimicrobials and the encoding genes were analyzed. 66, 26, 6.5, 3.9 and 1.3% were pan-susceptible or showed resistance to nalidixic acid (Asp87 to Tyr and Asp87 to Asn substitutions in GyrA), ampicillin (blaTEM-1-like and blaSHV), sulfonamides (sul1and sul3) and streptomycin (strB), respectively. A single isolate with intermediate susceptibility to ciprofloxacin was positive for qnrB, whereas qnrA, qnrS or aac(6′)-Ib-cr were not detected. The virulotype of the isolates was established by testing ten virulence genes. The orgA, ssaQ, mgtC, siiD, sopB genes, located on Salmonella pathogenicity islands, and spvC of the serotype-specific virulence plasmid, were common to all isolates. In contrast, the prophage-associated sopE-1, sodC1 and gipA genes and the fimbrial bcfC gene were variably represented. All isolates except one contained the virulence plasmid, which appeared either alone or together with one or more additional plasmids. One isolate carried a single plasmid of ca. 90 Kb which may be derived from the virulence plasmid (60 Kb). Overall, seven resistotypes, six virulotypes and six plasmid profiles were identified. XbaI-PFGE revealed four related pulsotypes (X1–X4), with 80% of the isolates sharing the X1 pattern. The latter isolates exhibited different resistance, virulence and plasmid profiles, suggesting that mobile genetic elements, particularly prophages and plasmids, are of central importance for the evolution and adaptation of S. Enteritidis circulating in chicken farms in Tunisia. Keywords: Poultry, Antimicrobial drug resistance, qnrB, Virulence genes, PFG

Contrasted resistance of stone-dwelling Geodermatophilaceae species to stresses known to give rise to reactive oxygen species

Stones in arid environments are inhabited by actinobacteria of the family Geodermatophilaceae like the genera Blastococcus and Modestobacter frequently isolated from altered calcarenites. Their habitat requires adaptation to light-induced and other stresses that generate reactive oxygen species. Here, we show that representative members of the species Blastococcus saxobsidens, Geodermatophilus obscurus, and Modestobacter multiseptatus are differentially adapted to stresses associated with arid environments. Whereas B. saxobsidens was found to be sensitive to gamma radiation (D10 = 900 Gy; 10% survival at 900 Gy), M. multiseptatus was moderately (D10 = 6000 Gy) and G. obscurus was highly tolerant (D10 = 9000 Gy). A difference in resistance to high-frequency (λ value = 254 nm) UV was shown by B. saxobsidens, M. multiseptatus, and G. obscurus, being sensitive, tolerant, and highly tolerant (D10 of 6, 900, and > 3500 kJ m-2, respectively). Tolerance to desiccation, mitomycin C and hydrogen peroxide correlated with the ionizing radiation and UV resistance profiles of the three species and were correlated with the pigments synthesized. Resistance to heavy metals/metalloids did not follow the same pattern, with resistance to Ag2+ and Pb2+ being similar for B. saxobsidens, M. multiseptatus, and G. obscurus, whereas resistance to AsO4 3-, Cr2+, or Cu2+ was greater for B. saxobsidens than for the other two species. The stress resistance profiles of M. multiseptatus and B. saxobsidens were reflected in different calcarenite colonization patterns. While M. multiseptatus was predominantly isolated from the first two millimeters of stone surface, B. saxobsidens was predominantly isolated from the deeper part of the stone where it is better protected from sun irradiation, suggesting that the response to light- and desiccation-induced oxidative stress is an important driver for niche colonization in the stone biotope. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved