Clinical isolates of Klebsiella pneumoniae producing NDM-1 carbapenemase from India ( n = 22), the United Kingdom ( n = 13), and Sweden ( n = 4) were subjected to multilocus sequence typing (MLST), automated repetitive sequence-based PCR (rep-PCR), serotyping, virulence gene screening, and plasmid replicon typing. The most frequently detected MLST sequence types (STs) were ST14 ( n = 13; all serotype K2), ST11, ST149, ST231, and ST147. The correlation between MLST and automated rep-PCR was excellent. IncA/C was the most frequently detected plasmid replicon type ( n = 14). ST14, ST11, and other successful clones may be important for the dissemination of bla _NDM-1 .

Antibiotics are the pivotal pillar of contemporary healthcare and have contributed towards its advancement over the decades. Antibiotic resistance emerged as a critical warning to public wellbeing because of unsuccessful management efforts. Resistance is a natural adaptive tool that offers selection pressure to bacteria, and hence cannot be stopped entirely but rather be slowed down. Antibiotic resistance mutations mostly diminish bacterial reproductive fitness in an environment without antibiotics; however, a fraction of resistant populations ‘accidentally’ emerge as the fittest and thrive in a specific environmental condition, thus favouring the origin of a successful resistant clone. Therefore, despite the time-to-time amendment of treatment regimens, antibiotic resistance has evolved relentlessly. According to the World Health Organization (WHO), we are rapidly approaching a ‘post-antibiotic’ era. The knowledge gap about antibiotic resistance and room for progress is evident and unified combating strategies to mitigate the inadvertent trends of resistance seem to be lacking. Hence, a comprehensive understanding of the genetic and evolutionary foundations of antibiotic resistance will be efficacious to implement policies to force-stop the emergence of resistant bacteria and treat already emerged ones. Prediction of possible evolutionary lineages of resistant bacteria could offer an unswerving impact in precision medicine. In this review, we will discuss the key molecular mechanisms of resistance development in clinical settings and their spontaneous evolution.

Significance: Populations of larger organisms should be more efficient in their resource use, but grow more slowly, than populations of smaller organisms. The relations between size, metabolism, and demography form the bedrock of metabolic theory, but most empirical tests have been correlative and indirect. Experimental lineages of Escherichia coli that evolved to make larger cells provide a unique opportunity to test how size, metabolism, and demography covary. Despite the larger cells having a relatively slower metabolism, they grow faster than smaller cells. They achieve this growth rate advantage by reducing the relative costs of producing their larger cells. That evolution can decouple the costs of production from size challenges a fundamental assumption about the connections between physiology and ecology.

VIM-producing Klebsiella pneumoniae (n = 21) isolated from ten Greek hospitals during 2003-2007 were characterized with multilocus sequence typing (MLST), semi-automated repetitive sequence-based PCR (rep-PCR) (Diversilab), plasmid replicon typing, serotyping and screening for multiple resistance determinants. The isolates were selected to represent different strain clusters (defined by >80% similarity) according to pulsed-field gel electrophoresis. MLST identified three major clonal complexes (CCs); CC147 (n = 8), CC18 (n = 5) and CC14 (n = 3). Plasmid replicon typing showed that IncA/C and/or IncFIIK replicons were detected among isolates in each of the major CCs. Good concordance was observed between semi-automated-rep PCR genotyping and MLST.