Demonstration of a shift towards penicillin resistance in the Streptococcus uberis population

Abstract

Demonstration of a shift towards penicillin resistance in the Streptococcus uberis population Penicillin resistance has been particularly well studied in Streptococcus pneumoniae (Denapaite et al., 2007; Hoban et al., 2005). In this organism, resistance frequently occurs through modifications of the penicillin-binding proteins (PBPs) and/or the generation of mosaic PBPs, leading to a decreased affinity for the drug (Nagai et al., 2002). Among clinically relevant streptococci, S. pneumoniae primarily infects humans, while the environmental Streptococcus uberis principally colonizes cattle, in which it is responsible for about one third of cases of clinical and subclinical mastitis (Botrel et al., 2010; Bradley et al., 2007), a type of disease causing major economic loss in the dairy industry worldwide. Currently, penicillin remains one of the first-line antibiotics for the treatment of such pathologies but, in contrast to pneumococci and despite several decades of widespread use, no field case of true penicillin-resistant S. uberis [MIC .16 mg l 21 , according to the CA-SFM (Comité de l'Antibiogramme de la Société Française de Microbiologie)-Antibiogram Committee of the French Society for Microbiology] has been described yet. Furthermore, it is still commonly believed that S. uberis and other Streptococcus spp. implicated in animal intramammary infections are susceptible to this drug. However, isolates presenting decreased susceptibility (MIC of 0.25 to 0.5 mg l 21) are regularly reported to our laboratory, and a recent study demonstrated the capacity of S. uberis to develop penicillin resistance through a PBP-mediated mechanism similar to S. pneumoniae and the other streptococci studied so far (Haenni et al., 2010).

Short communication: Streptococcus species isolated from mastitis milk samples in Germany and their resistance to antimicrobial agents

“…Pirlimycin resistance among streptococci has been reported previously (Rossitto et al, 2002;Pol and Ruegg, 2007a;Schmitt-Van de Leemput and Zadoks, 2007;GERMAP, 2008;Haenni et al, 2010). In the present study, high levels of pirlimycin resistance (MIC ≥16 mg/L) were found (Table 1), whereby Strep.…”

“…Decreased susceptibility to penicillin has, however, been reported previously (Erskine et al, 2002;Guérin-Faublée et al, 2002;Rossitto et al, 2002). Haenni et al (2010) reported that a subpopulation of Strep. uberis field isolates shifted toward resistance against penicillin, despite the fact that all of these isolates were still considered sensitive to this antimicrobial.…”

“…Mastitis therapy is commonly initiated before susceptibility testing of the pathogen (Guterbock et al, 1993;Guérin-Faublée et al, 2002;Hendriksen et al, 2008). The most commonly used antimicrobial classes for the treatment of streptococcal mastitis are β-lactams and macrolides (Denamiel et al, 2005;Tenhagen et al, 2006;Haenni et al, 2010;Kalmus et al, 2011). Because the emergence of resistant pathogens is of growing concern in veterinary medicine, performing susceptibility tests during the bacteriological examination of mastitis milk samples is an important basis for the selection of the appropriate chemotherapeutic agents (Schwarz et al, 2003).…”

Effects of Dietary Vibroactivated Clinoptilolite Supplementation on the Intramammary Microbiological Findings in Dairy Cows

“…Unlike previous findings, resistance to penicillin was found in S. aureus and [15] CNS isolates (61.4% and 38.5%, respectively) [13], which was similar to our study (61.11% and 46.15%, respectively). The most effective antimicrobial substances for the treatment of streptococcal mastitis were β-lactams and macrolides [13,[21][22][23][24], as confirmed in our study. The rate of multiresistance to antibiotics was higher in Str.…”

“…Bacterial resistance to tetracycline was detected the most frequently [24][25][26][27]. Although β-Lactams are the best choice in the treatment of streptococcal mastitis [22][23][24][25][26][28][29][30], in our study, all isolates were fully susceptible to cefoperazone [29], penicillin, and ampicillin. The administration of clinoptilolite alone, and particularly in combination with selenium, increased the antibody titres against E. coli in the blood serum of heifers and calves [31].…”