Phylogenetic analyses suggest multiple changes of substrate specificity within the Glycosyl hydrolase 20 family

<p>Abstract</p> <p>Background</p> <p>Beta-N-acetylhexosaminidases belonging to the glycosyl hydrolase 20 (GH20) family are involved in the removal of terminal β-glycosidacally linked N-acetylhexosamine residues. These enzymes, widely distributed in microorganisms, animals and plants, are involved in many important physiological and pathological processes, such as cell structural integrity, energy storage, pathogen defence, viral penetration, cellular signalling, fertilization, development of carcinomas, inflammatory events and lysosomal storage diseases. Nevertheless, only limited analyses of phylogenetic relationships between GH20 genes have been performed until now.</p> <p>Results</p> <p>Careful phylogenetic analyses of 233 inferred protein sequences from eukaryotes and prokaryotes reveal a complex history for the GH20 family. In bacteria, multiple gene duplications and lineage specific gene loss (and/or horizontal gene transfer) are required to explain the observed taxonomic distribution. The last common ancestor of extant eukaryotes is likely to have possessed at least one GH20 family member. At least one gene duplication before the divergence of animals, plants and fungi as well as other lineage specific duplication events have given rise to multiple paralogous subfamilies in eukaryotes. Phylogenetic analyses also suggest that a second, divergent subfamily of GH20 family genes present in animals derive from an independent prokaryotic source. Our data suggest multiple convergent changes of functional roles of GH20 family members in eukaryotes.</p> <p>Conclusion</p> <p>This study represents the first detailed evolutionary analysis of the glycosyl hydrolase GH20 family. Mapping of data concerning physiological function of GH20 family members onto the phylogenetic tree reveals that apparently convergent and highly lineage specific changes in substrate specificity have occurred in multiple GH20 subfamilies.</p

A rare case of enteric and systemic Yersinia enterocolitica infection in a chronic, not iron-overloaded dialysis patient

We present herein a case of bacterial gastroenteritis due to Yersinia enterocolitica, occurred in a young woman undergoing haemodialysis with a previous history positive for prolonged (20 years) immunosuppressive therapy for glomerulonephritis before and for kidney transplant later. The patient's outcome was favourable after a third-generation cephalosporin treatment without complications. The possible pathophysiological association between patient clinical condition and Yersinia bacteraemia is discussed, along with the review of literature

Bacillus pumilus severe wound infection in a healthy ten years old child: a rare case report

Bacillus pumilus is commonly isolated from a wide variety of soils, plants and environmental surfaces, but rarely from human specimens. In this report, we describe a case of infection caused by B. pumilus in a healthy 10-years-old child. The microorganism was recovered from a severe wound of the left knee after three days from trauma. Pathogen identification was carried out by mass spectrometry. The patient's outcome was positive following an ampicillin/sulbactam treatment without complications

Fusarium solani infection after antimicrobial treatment of a severe bacterial peritonitis: a case report and review of the literature

Fungal peritonitis is a rare but serious complication of peritoneal dialysis. This infection has been reported to be mostly caused by Candida species, and less frequently by a variety of other yeasts and moulds, such as Aspergillus, Penicillium, and  Fusarium spp. are commonly isolated from soil, plants and environmental surfaces, and rarely from non-immunosuppressed subjects. In this report, author describe a case of infection caused by Fusarium solani in a 59-year-old man undergoing continuous ambulatory peritoneal dialysis. The fungus was recovered from cultures of peritoneal dialysate and the pathogen identification was carried out by mass spectrometry. The patient's outcome was favorable without complications after liposomal amphotericin B treatment along with peritoneal dialysis catheter removal

A rare case of enteric and systemic Yersinia enterocolitica infection in a chronic, not iron-overloaded dialysis patient

We present herein a case of bacterial gastroenteritis due to Yersinia enterocolitica, occurred in a young woman undergoing haemodialysis with a previous history positive for prolonged (20 years) immunosuppressive therapy for glomerulonephritis before and for kidney transplant later. The patient’s outcome was favourable after a third-generation cephalosporin treatment without complications. The possible pathophysiological association between patient clinical condition and Yersinia bacteraemia is discussed, along with the review of literature

Rapid acquisition and modulation of colistin-resistance by an extensively drug-resistant Acinetobacter baumannii: case report and review of current literature

Acinetobacter baumannii has emerged as a major cause of healthcare-associated infections. It commonly expresses clinical resistance to multiple antimicrobial agents, and hence, it is considered the paradigm of an extensively drug-resistant (XDR) bacterium. XDR A. baumannii is a rapidly emerging pathogen, especially in the intensive care unit (ICU), causing nosocomial infections including sepsis, ventilatorassociated pneumonia, meningitis, peritonitis, urinary tract infection, and central venous catheter-related infection. In the present report, we described an in vivo evolution of A. baumannii strain from a colistinsusceptibility to a colistin-resistance state. A 65-year-old male, who suffered a duodenal ulcer, two days after hospitalization and during the stay in ICU, contracted a pneumonia and peritoneal infection by a carbapenem-resistant A. baumannii strain. After a combination treatment with colistin, vancomycin plus imipenem, and within seven days, the pathogen rapidly evolved in seven days to a pandrug-resistant phenotype. As the antimicrobial treatment was stopped, the A. baumannii isolate changed another time its profile to colistin, becoming newly susceptible, showing a very high level of adaptability to external conditions. We also have reviewed here the current literature on this worryingly public health threat

Rapid acquisition and modulation of colistin-resistance by an extensively drug-resistant Acinetobacter baumannii: case report and review of current literature

Acinetobacter baumannii has emerged as a major cause of healthcare-associated infections. It commonly expresses clinical resistance to multiple antimicrobial agents, and hence, it is considered the paradigm of an extensively drug-resistant (XDR) bacterium. XDR A. baumannii is a rapidly emerging pathogen, especially in the intensive care unit (ICU), causing nosocomial infections including sepsis, ventilatorassociated pneumonia, meningitis, peritonitis, urinary tract infection, and central venous catheter-related infection. In the present report, we described an in vivo evolution of A. baumannii strain from a colistinsusceptibility to a colistin-resistance state. A 65-year-old male, who suffered a duodenal ulcer, two days after hospitalization and during the stay in ICU, contracted a pneumonia and peritoneal infection by a carbapenem-resistant A. baumannii strain. After a combination treatment with colistin, vancomycin plus imipenem, and within seven days, the pathogen rapidly evolved in seven days to a pandrug-resistant phenotype. As the antimicrobial treatment was stopped, the A. baumannii isolate changed another time its profile to colistin, becoming newly susceptible, showing a very high level of adaptability to external conditions. We also have reviewed here the current literature on this worryingly public health threat

Antimicrobial Resistance Patterns of <i>Enterobacter cloacae</i> and <i>Klebsiella aerogenes</i> Strains Isolated from Clinical Specimens: A Twenty-Year Surveillance Study

We retrospectively analyzed the antimicrobial data of Enterobacter spp. strains isolated from hospitalized subjects and outpatients over 20 years (2000–2019). A total of 2277 non-duplicate Enterobacter spp. isolates, 1037 from outpatients (45%) and 1240 from hospitalized subjects (55%), were retrieved. Most of samples are infections of the urinary tract. Considering Enterobacter aerogenes, now classified as Klebsiella aerogenes, and Enterobacter cloacae, representing more than 90% of all isolates, except for aminoglycosides and fluroquinolones, which showed significant antibiotic decreasing trends (p p > 0.05). Conversely, there was a significant increasing resistance trend for fosfomycin (p < 0.01), among both community and hospital-related subjects, most probably owing to uncontrolled and improper usage. Surveillance studies on antibiotic resistance at the local and regional level are required to detect new resistance mechanisms, reduce inappropriate antimicrobial consumption, and increase the focus on antimicrobial stewardship