Tweet
Published Date: 2013-11-25 22:02:31
Subject: PRO> Antibiotic resistance - USA (03): vancomycin, comment
Archive Number: 20131125.2073470
ANTIBIOTIC RESISTANCE - USA (03): VANCOMYCIN, COMMENT
************************************************** ***
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Fri 22 Nov 2013
From: Veronika Oravcova <oravcova.veronica@gmail.com> [edited]
[Re: ProMED-mail Antibiotic resistance - USA (02): vancomycin, comment 20131118.2061191]
----------------------------------------------------------------------
[I would like to respond to the comment made by Prof. Martin Hugh-Jones, regarding the topic "Antibiotic resistance - USA: vancomycin, crow"]
Thank you for your very important comment. You are right that the prevalence of VRE [vancomycin resistant enterococci] in crow feces in our study is not very high and we can be really glad about it. But it is important to note the differences between localities. In California we didn't find any VRE (from almost 200 samples), but in Massachusetts 13 crows (from 200) were colonized by VRE, and some of them with more than one isolate; so we obtained 19 different vanA-carrying enterococci from this sampling site. I believe that this is not just coincidence and normal genetic wobbling.
Is 3 per cent antibiotic resistance in any large collection from wildlife normal? From my experience in VRE research it is not. We sampled many sources (more than 2000 samples from wildlife in Europe) in which we didn't find any vanA-carrying VRE. Also, in a study in Canada (still unpublished) we found only one _E. faecium_ carrying vanA (from almost 450 samples of crow feces), so the prevalence was just 0.2 per cent. Similarly, Lanthier et al (2010, 2011) conducted 2 studies in North America, where they tested 1460 and 1558 enterococci strains (from wastewater, river, domesticated animals and wildlife) and none of them carried the vanA gene. Dr Zurek has not detected a single strain of vancomycin resistant _E. faecalis_ or _E. faecium_ from the food animal environment (swine, cattle, and bison) and associated insects in the USA over the past 10 years. And he analyzed hundreds of samples from different states (such as, Ahmad et al, 2011; Amachawadi et al, 2010; Anderson et al, 2008; Larson et al, 2008). So I think the vanA gene does not occur normally in wildlife. I agree with the fact that resistance to vancomycin can occur normally in some strains of _Enterococcus_ (_E. casseliflavus_, _E. gallinarum_, _E. flavescens_), but this is encoded by the vanC gene, carried on the chromosome and causing just low level resistance.
Further, it is not only about the vancomycin resistance in these strains, but also the multiresistance of the isolates to several other important antibiotics used for treatment of serious human infections. The isolates also carried very important virulence factors and belonged to clinically important sequence types previously found in pathogenic isolates from humans (Freitas et al, 2013; Klare et al, 2005; Lopez et al, 2012). That means that isolates like these are often responsible for serious nosocomial infections, and are found in hospitals. These observations, taken together, strongly suggest that the VRE we detected in crows comes from a human source.
Subject: PRO> Antibiotic resistance - USA (03): vancomycin, comment
Archive Number: 20131125.2073470
ANTIBIOTIC RESISTANCE - USA (03): VANCOMYCIN, COMMENT
************************************************** ***
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Fri 22 Nov 2013
From: Veronika Oravcova <oravcova.veronica@gmail.com> [edited]
[Re: ProMED-mail Antibiotic resistance - USA (02): vancomycin, comment 20131118.2061191]
----------------------------------------------------------------------
[I would like to respond to the comment made by Prof. Martin Hugh-Jones, regarding the topic "Antibiotic resistance - USA: vancomycin, crow"]
Thank you for your very important comment. You are right that the prevalence of VRE [vancomycin resistant enterococci] in crow feces in our study is not very high and we can be really glad about it. But it is important to note the differences between localities. In California we didn't find any VRE (from almost 200 samples), but in Massachusetts 13 crows (from 200) were colonized by VRE, and some of them with more than one isolate; so we obtained 19 different vanA-carrying enterococci from this sampling site. I believe that this is not just coincidence and normal genetic wobbling.
Is 3 per cent antibiotic resistance in any large collection from wildlife normal? From my experience in VRE research it is not. We sampled many sources (more than 2000 samples from wildlife in Europe) in which we didn't find any vanA-carrying VRE. Also, in a study in Canada (still unpublished) we found only one _E. faecium_ carrying vanA (from almost 450 samples of crow feces), so the prevalence was just 0.2 per cent. Similarly, Lanthier et al (2010, 2011) conducted 2 studies in North America, where they tested 1460 and 1558 enterococci strains (from wastewater, river, domesticated animals and wildlife) and none of them carried the vanA gene. Dr Zurek has not detected a single strain of vancomycin resistant _E. faecalis_ or _E. faecium_ from the food animal environment (swine, cattle, and bison) and associated insects in the USA over the past 10 years. And he analyzed hundreds of samples from different states (such as, Ahmad et al, 2011; Amachawadi et al, 2010; Anderson et al, 2008; Larson et al, 2008). So I think the vanA gene does not occur normally in wildlife. I agree with the fact that resistance to vancomycin can occur normally in some strains of _Enterococcus_ (_E. casseliflavus_, _E. gallinarum_, _E. flavescens_), but this is encoded by the vanC gene, carried on the chromosome and causing just low level resistance.
Further, it is not only about the vancomycin resistance in these strains, but also the multiresistance of the isolates to several other important antibiotics used for treatment of serious human infections. The isolates also carried very important virulence factors and belonged to clinically important sequence types previously found in pathogenic isolates from humans (Freitas et al, 2013; Klare et al, 2005; Lopez et al, 2012). That means that isolates like these are often responsible for serious nosocomial infections, and are found in hospitals. These observations, taken together, strongly suggest that the VRE we detected in crows comes from a human source.
Comment