Identification and characterization of multidrug-resistant ESBL-producing Salmonella enterica serovars Kentucky and Typhimurium isolated in Tunisia CTX-M-61/TEM-34, a novel cefotaxime-hydrolysing ß-lactamase of Salmonella.

AIMS: Molecular characterization of extended-spectrum ß-lactamases (ESBLs) among Salmonella Kentucky and Typhimurium isolates: partial sequence analysis of the types of ß-lactamases found in these isolates, clonality, resistance and supposed emergence of ESBL-producing strains. METHODS AND RESULTS: A retrospective study surveyed the ESBLs occurring in a total of 1404 Salmonella Kentucky and Typhimurium isolates collected over a 5-year period in Tunisia. Antimicrobial susceptibility tests, ESBL phenotype determination (double-disc synergy) were performed. Polymerase chain reaction assays were used for the detection of ß-lactamase genes (blaTEM , blaSHV , blaOXA-1 and blaCTX-M ), class 1 and class 2 integrases (intI1 and intI2) and the 3' conserved segment (3'-CS) of class 1 integron (qacEΔ1+sul1). Sequencing of amplicons of ß-lactamase genes was performed. Percentage of 9.8 of the isolates (S. Kentucky = 117, S. Typhimurium = 20) were either resistant to penicillin and had decreased susceptibility to cefotaxime or had a positive double-disc synergy test result. Polymerase chain reaction detected that these isolates harboured one or more ß-lactamase genes (blaTEM , blaSHV , blaOXA-1 or blaCTX-M ). TEM-1, TEM-34, CTX-M15, CTX-M9 and CTX-M61 type ESBLs were identified through sequencing. The novel Salmonella cefotaxime-hydrolysing ß-lactamase, CTX-M61/TEM-34, detected in this study showed the emergence of new CTX-M-type ESBLs in Tunisia. There were found 33 different multidrug resistance (MDR) patterns. CONCLUSION: These findings highlighted the proliferation of ESBLs and MDR in Salmonella Kentucky and Typhimurium isolates from numerous regions and sources in Tunisia, indicating an emerging public health concern. SIGNIFICANCE AND IMPACT OF THE STUDY: For the first time CTX-M-61/TEM-34, a novel cefotaxime-hydrolysing ß-lactamase of Salmonella had been detected.

SARS-CoV-2-Associated Guillain-Barre Syndrome is Common but Under- recognised and Under- reported.

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PIK3CA mutations in breast cancer: A Tunisian series.

BACKGROUND: The aim of this study was to analyze PIK3CA mutations in exons 9 and 20 in breast cancers (BCs) and their association with clinicopathological characteristics. METHODS: Mutational analysis of PIK3CA exon 9 and 20 was performed by Sanger sequencing in 54 primary BCs of Tunisian women. The associations of PIK3CA mutations with clinicopathological characteristics were analyzed. RESULTS: Fifteen exon 9 and exon 20 PIK3CA variants were identified in 33/54 cases (61%). PIK3CA mutations including pathogenic (class 5/Tier I) or likely pathogenic (class 4/Tier II) occurred in 24/54 cases (44%): 17/24 cases (71%) in exon 9, 5/24 cases (21%) in exon 20 and 2/24 cases (8%) in both exons. Of these 24 cases, 18 (75%) carried at least one of the three hot spot mutations: E545K (in 8 cases), H1047R (in 4 cases), E542K (in 3 cases), E545K/E542K (in one case), E545K/H1047R (in one case) and P539R/H1047R (in one case). Pathogenic PIK3CA mutations were associated with negative lymph node status (p = 0.027). Age distribution, histological SBR tumor grading, estrogen and progesterone receptors, human epidermal growth factor receptor 2, and molecular classification were not correlated with PIK3CA mutations (p > 0.05). CONCLUSION: The frequency of somatic PIK3CA mutations in BCs of Tunisian women is slightly higher than that of BCs of Caucasian women and more observed in exon 9 than in exon 20. PIK3CA mutated status is associated with negative lymph node status. These data need to be confirmed in larger series.

Fatigue and Exercise Intolerance as Initial Manifestations of a Nonsyndromic Mitochondrial Disorder Due to the Variant m.3243A>G.

Objectives: Fatigue and exercise intolerance have been only rarely reported as initial- and sole-onset manifestations of a mitochondrial disorder (MID). We present a patient with nonsyndromic MID with fatigue and exercise intolerance as its initial manifestations of the disease. Case Report. A 39 yo female experienced fatigue since age 18 and exercise intolerance since age 21. Later on, she developed Hashimoto thyroiditis, recurrent diffuse headache, and double vision upon exercise. Clinical exam revealed short stature, bilateral ptosis, partially reduced tendon reflexes, and hypertrophic calves. Serum lactate was elevated, and the lactate stress test was abnormal. Workup for suspected MID revealed ragged-red fibers and NADH-deficient muscle fibers, and biochemical investigations revealed a mild complex-I defect. mtDNA sequencing revealed the variant m.3243A>G with a heteroplasmy rate of 70% in the muscle. Conclusions: This case shows that the initial manifestation of a MID can be fatigue and exercise intolerance. MIDs due to the m.3243A>G variant may have a slowly progressive course and only delayed multisystem involvement. The variant m.3243A>G may not only manifest as syndromic MID, particularly MELAS but also as nonsyndromic phenotype. MIDs should be considered as differentials of chronic fatigue even if no other phenotypic manifestation of a MID is present.

Ischemic and Metabolic Stroke Can Co-occur in m.3243A>G Carriers: A Case Report.

Stroke-like episodes (SLEs) and their morphological equivalent, stroke-like lesions (SLLs), also termed metabolic stroke, are the hallmark of MELAS. Despite increasing knowledge of the properties of SLEs/SLLs, they are often misinterpreted as ischemic stroke, particularly if both ischemic and metabolic stroke occur in the same patient. The patient is a 56 years-old male with MELAS due to the mtDNA variant m.3243A>G in MT-TL1 and three previous strokes at ages 43 years, 49 years, and 50 years being interpreted as ischemic, focal seizures, depression, right amblyopia, hypoacusis, hyperuricemia, hepatic steatosis, hyperlipidemia, pre-diabetes, and arterial hypertension. He was admitted due to successive worsening of a pre-existing gait disturbance and confusion. Clinical exam revealed dysarthria, word-finding difficulties, right-left confusion disorder, left visual neglect, ataxia, and pyramidal signs. Cerebral MRI showed T2- and DWI hyperintense lesions in a right occipitotemporal location not confined to a vascular territory and in the left posterior border zone. The right occipitotemporal lesion was initially interpreted as subacute ischemia, which is why acetyl-salicylic acid was replaced by clopidogrel. However, after revision of the MRI images, the right occipitotemporal lesion was re-classified as SLL. Arguments for an SLL (metabolic stroke) were the successive onset and the distribution of the lesion. The patient recovered partially from his initial deficits within eight weeks. In summary, SLLs can co-occur with ischemic stroke in the same MELAS patient. Further efforts are needed to clearly differentiate metabolic from ischemic stroke in MELAS patients.

Combining Gene Mutation with Expression of Candidate Genes to Improve Diagnosis of Escobar Syndrome.

Escobar syndrome is a rare, autosomal recessive disorder that affects the musculoskeletal system and the skin. Mutations in the CHRNG and TPM2 genes are associated with this pathology. In this study, we conducted a clinical and genetic investigation of five patients and also explored via in silico and gene expression analysis their phenotypic variability. In detail, we identified a patient with a novel composite heterozygous variant of the CHRNG gene and two recurrent mutations in both CHRNG and TPM2 in the rest of the patients. As for the clinical particularities, we reported a list of modifier genes in a patient suffering from myopathy. Moreover, we identified decreased expression of IGF-1, which could be related to the short stature of Escobar patients, and increased expression of POLG1 specific to patients with TPM2 mutation. Through this study, we identified the genetic spectrum of Escobar syndrome in the Tunisian population, which will allow setting up genetic counseling and prenatal diagnosis for families at risk. In addition, we highlighted relevant biomarkers that could differentiate between patients with different genetic defects.

Sinus venous thrombosis as a complication of COVID-19-associated hypercoagulability.

Sinus venous thrombosis (SVT) is an increasingly recognised complication of not only SARS-CoV-2 infections, but also of SARS-CoV-2 vaccinations. SVT is attributed to hypercoagulability, a common complication of COVID-19, disregarding the severity of the infection. Hypercoagulability in COVID-19 is explained by direct activation of platelets, enhancing coagulation, by direct infection and indirect activation of endothelial cells by SARS-CoV-2, shifting endothelial cells from an anti-thrombotic to a pro-thrombotic state, by direct activation of complement pathways, promoting thrombin generation, or by immune thrombocytopenia, which also generates a thrombogenic state. Since SVT may occur even in anticoagulated COVID-19 patients and may have an unfavourable outcome, all efforts must be made to prevent this complication or to treat it accurately.

Post-SARS-CoV-2 vaccination venous sinus thrombosis: a literature review of 308 cases.

There is accumulating evidence that SARS-CoV-2 vaccinations can be complicated by venous sinus thrombosis (VST). This review aimed at summarising and discussing previous and recent advances regarding the diagnosis, pathogenesis, treatment, and outcome of post-SARS-CoV-2 vaccination VST. At least 308 patients with post-SARS-CoV-2 vaccination VST have been reported as per the end of July 2021. Ages among these 308 patients ranged between 22 and 81 years, 69 were male and 197 were female. Post-SARS-CoV-2 vaccination VST most commonly occurred with the ChAdOx1-S vaccine followed by the BNT126b2 vaccine. In the vast majority of cases, VST occurred after the first dose. Only in six patients did VST occur after the second dose. Latency between vaccination and onset of VST ranged between 0 and 24 days. Regarding treatment, most patients received heparin followed by oral anticoagulants. Seven patients received IVIGs and six patients received steroids because of concomitant vaccine-induced immune thrombotic thrombocytopenia. Complete recovery was reported in 5 patients. Partial recovery was reported in 9 patients. Eight patients were alive or discharged. Sixty-two patients died. The outcome was not specified in the remainder. In conclusion, SARS-CoV-2 vaccinations can be complicated by VST. There is female preponderance and the outcome is frequently poor.

Dilated Cardiomyopathy due to the Novel MT-CYB Missense Mutation m.14757T>C.

Mitochondrial DNA (mtDNA) mutations frequently manifest with multisystem disease, including cardiomyopathy (CM). Various studies described mutations in protein-encoding mtDNA genes, such as cytochrome-b, manifesting with CM. A detailed clinical, biochemical, and molecular genetic analysis was performed in a 40-year-old male with dilated CM (DCM) to detect the underlying mtDNA defect. Muscle biopsy showed complex-III deficiency, and sequencing of the cytochrome-b gene revealed the pathogenic variant m.14757T>C in MT-CYB, resulting in the replacement of the hydrophobic methionine by the polar threonine (M4T). By application of the PolyPhen algorithm the variant was predicted as pathogenic. The mutation was not found in 100 healthy controls and never reported as a neutral polymorphism despite extensive sequencing of the cytochrome-b gene in 2,704 normal healthy controls from different ethnic backgrounds. In conclusion, the novel variant m.14757T>C in MT-CYB is associated with DCM suggesting a pathophysiologic role of the variant in the development of DCM.

Identification and Characterization of a Novel Recurrent ERCC6 Variant in Patients with a Severe Form of Cockayne Syndrome B.

Cockayne syndrome (CS) is a rare disease caused by mutations in ERCC6/CSB or ERCC8/CSA. We report here the clinical, genetic, and functional analyses of three unrelated patients mutated in ERCC6/CSB with a severe phenotype. After clinical examination, two patients were investigated via next generation sequencing, targeting seventeen Nucleotide Excision Repair (NER) genes. All three patients harbored a novel, c.3156dup, homozygous mutation located in exon 18 of ERCC6/CSB that affects the C-terminal region of the protein. Sanger sequencing confirmed the mutation and the parental segregation in the three families, and Western blots showed a lack of the full-length protein. NER functional impairment was shown by reduced recovery of RNA synthesis with proficient unscheduled DNA synthesis after UV-C radiations in patient-derived fibroblasts. Despite sharing the same mutation, the clinical spectrum was heterogeneous among the three patients, and only two patients displayed clinical photosensitivity. This novel ERCC6 variant in Tunisian patients suggests a founder effect and has implications for setting-up prenatal diagnosis/genetic counselling in North Africa, where this disease is largely undiagnosed. This study reveals one of the rare cases of CS clinical heterogeneity despite the same mutation. Moreover, the occurrence of an identical homozygous mutation, which either results in clinical photosensitivity or does not, strongly suggests that this classic CS symptom relies on multiple factors.