Clinical Isolates of Staphylococcus aureus Show Variation in β-Lactamase Production and Are More Susceptible to Antibiotics Conjugated with β-Lactamase Inhibitors

β-Lactam antibiotics are a cornerstone in the treatment of bacterial infections on account of its high therapeutic index and selective toxicity—they act by inhibiting the biosynthesis of peptidoglycan, a key component in bacterial cell wall. Ninety (90) clinical specimens obtained from the microbiology unit Specialist Hospital Bauchi were screened for S. aureus, positive isolates were examined for β-Lactamase expression by using two Penicillin G concentrations (5000 IU/ml and 25,000 IU/ml) in acidometric agar technique with phenol red as indicator, and the susceptibility pattern of the isolates to β-Lactam antibiotics was also determined. S. aureus prevalence of 31% (28/90) was obtained, of which 96% (27/28) of strains were β-Lactamase positive in the standard test, while 63% (17/27) were able to hydrolyze penicillin G concentration of 25,000 IU/ml (5X the concentration in the standard test), and a strain was found to be β-Lactamase negative. The resistance to five β-Lactams, ampicillin, cephalexin, amoxicillin, cloxacillin and flucloxaillin, were 100%, 96%, 89%, 74% and 56% respectively. When ampicillin and amoxicillin were conjugated to β-Lactamase inhibitors sulbactam and clavulanic acid respectively the resistance to ampicillin decreased to 21% and to amoxicillin to 15%. The antibiotic susceptibility profile revealed β-Lactamase elaboration to be the major mechanism of resistance to the β-Lactams. β-Lactam utilization as therapeutic option would thus require the search for sensitive irreversible β-Lactamase inhibitors for the β-Lactamase enzymes or agents to block the release of β-Lactamase by strains.

Forecasting the number of species of asexually reproducing fungi(Ascomycota and Basidiomycota)

Asexually reproducing fungi play a significant role in essential processes in managed and wild ecosystems such as nutrients cycling and multitrophic interactions.A large number of such taxa are among the most notorious plant and animal pathogens.In addition,they have a key role in food production,biotechnology and medicine.Taxa without or rare sexual reproduction are distinguished based on their sporulating structures and conidiomata in traditional morphology-based taxonomy.The number,variation and diversity of asexually reproducing taxa are insufficiently known,even though fungi capable of asexual reproduction may provide an untapped,rich biological resource for future exploitation.Currently,ca.30,000 asexual species belonging to ca.3800 genera have been reported(including 1388 coelomycetous and 2265 hyphomycetous genera).Recent reports(2017–2020)reiterate that the number of asexually producing fungi is higher than the number of frequently sexually-reproducing fungi.With the advent of molecular tools and the abandonment of the dual nomenclature system for pleomorphic fungi,priority criteria were established and revisited in the latest outline of fungi and fungus-like taxa.However,species numbers and taxonomic boundaries of pleomorphic taxa and their synanamorphs or synasexual morphs have yet to be addressed.The number of species of speciose genera(e.g.Alternaria,Aspergillus,Cercospora,Fusarium,Phoma and Pseudocercospora),cryptic species,species of pleomorphic genera,less studied life modes(such as lichenicolous taxa,taxa from extreme environments)and species from biodiversity-rich areas still need evaluation to achieve more reliable estimates of their diversity.This paper discusses the current knowledge on the matter,with diversity estimates,and potential obstacles in several chapters on(1)speciose genera;(2)pleomorphic genera;(3)cryptic species;(4)well-studied but insufficiently resolved taxa,e.g.leaf inhabiting species,marine fungi,(5)less studied life modes,e.g.lichenicolous,rock-inhabiting fungi,insect-associated and yeast-forming taxa and(6)species from biodiversity-rich areas.