International Pneumococcal Clones Match or Exceed the Fitness of Other Strains despite the Accumulation of Antibiotic Resistance

Abstract

A few international pneumococcal clones dominate the population of antibiotic-resistant pneumococci. Despite the scientific paradigm that a loss in fitness is the price for acquisition of resistance, these clones spread successfully. One hundred fifty-four isolates from adult patients with community-acquired pneumonia (CAP) were analyzed. Thirty percent showed a close relationship to international clones and had fitness equal to or exceeding that of other strains (P ‫؍‬ 0.015); these factors may result in the endurance of these strains despite a reduction of antibiotic usage.

Antimicrobial Resistance in the Food Chain: A Review

“…with resistance to rifampicin [17]. Whereas for other bacteria and resistance types, antimicrobial resistance in pneumococci is accompanied by unchanged or increased biological fitness when compared to sensitive pneumococci [18]. …”

Double-Serine Fluoroquinolone Resistance Mutations Advance Major International Clones and Lineages of Various Multi-Drug Resistant Bacteria

“…Prior to the advent of vaccination fluoroquinolone resistant S. pneumoniae strains used to often disseminate clonally and the isolates primarily carried double-serine mutations (Pletz et al, 2004 ; Adam et al, 2007 ; Hsieh et al, 2010 ; Rodríguez-Avial et al, 2011 ). Interestingly strains from these fluoroquinolone-resistant S. pneumoniae clones did not show any fitness cost and even have sometimes exceeded wild type strains in propagation assays (Rudolf et al, 2011 ).…”

Reversibility of antibiotic resistance

“…This was attributed to a clonal spread of successful PNSP serotypes ( 55,56 ). Two recent studies on S. pyogenes ( 57 ) and S. pneumoniae ( 58 ) further emphasize the importance of successful resistant clones as an important cause of both the rise and fall of resistance in bacteria not considered as normal flora. The Korean study on S. pyogenes showed that a nationwide decrease in erythromycin resistance was due to a decrease of a certain resistant emm -type rather than due to decreased erythromycin use ( 57 ).…”

“…In S. pneumoniae , successful multi-resistant clones have been shown to have increased fitness despite the accumulation of antibiotic resistance, challenging reduced antibiotic use to be effective in controlling these clones. A large proportion of these clones, however, belonged to serotypes covered in the 7-valent conjugate vaccine now being used, thus limiting their spread ( 58 ). In Enterobacteriaceae the impact of antibiotic restriction policies seems very limited.…”

“…However, new strategies might prove efficient to counteract resistance development in some species. Vaccination against important serotypes of S. pneumoniae has been proven effective in reducing antibiotic resistance in clinical infections ( 58,67 ).…”