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Molecular characterization of Methicillin-resistant Staphylococcus aureus from intensive care unit in Aberdeen Royal Infirmary, Scotland
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Introduction Pneumocystis jirovecii is ubiquitous in the environment and an opportunistic pathogen which causes pneumonia in high risk patient groups e.g. immunocompromised patients, especially those with HIV, leukaemia and transplant patients. P. jirovecii pneumonia (PCP) has typically been diagnosed by a combination of immunofluorescence (IF) testing in the diagnostic laboratory and the clinical picture in the patient. However, IF despite having a good positive predictive value is an insensitive method. Increasingly molecular methods such as PCR are being used in the diagnosis of PCP. We describe the evaluation of a novel internally controlled real-time PCR, targeting the ß-tubulin gene for the diagnosis of PCP in induced sputum or broncheoalveolar lavage fluid. Also, in response to an outbreak of PCP cases in renal transplant patients at the Royal Liverpool University Hospital, genotypic sequencing (two gene fragments) of real-time PCR positive samples was undertaken. To determine the epidemiology, cases were compared with non-renal transplant controls. Both methods were adapted for testing of environmental (air and hard surface) sampling for P. jirovecii to investigate a common infection source.
Scientific findings The P. jirovecii real-time PCR has a detection limit of 350 gene copies/mL and 100% specificity. All IF positive samples and an additional fourteen samples that were IF negative were positive by real-time PCR. Of the renal transplant outbreak cases, samples were available from 18 and of these 17 were real-time PCR positive. Fourteen of 17 patients assessed shared the same genotype which was different from the non-renal controls. Environmental sampling detected P. jirovecii in the air and on surfaces and these strains comprised multiple genotypes including the one which predominated in the outbreak.
Discussion P. jirovecii real-time PCR improved the laboratory diagnosis of PCP compared with IF. Sequencing based genotyping showed that a common genotype predominated in the outbreak cases. In addition, environmental sampling detected P. jirovecii in clinical areas where patients had been. These findings influenced clinical management of patients through the extension of prophylaxis. The mode of transmission in the outbreak is still not clear. However, detection of P. jirovecii of the predominating genotype in the air cannot rule out the environment as a source.
Conclusions
Abstracts
MOLECULAR CHARACTERIZATION OF METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS FROM INTENSIVE CARE UNIT IN ABERDEEN ROYAL INFIRMARY, SCOTLANDCATEGORY: LESSON IN MICROBIOLOGY & INFECTION CONTROL Vartul Sangal 1, Kirsty Girvan 2, Sagar Jadhav 1, Leila Vali 1, Giles FS Edwards 2, Jun Yu 1, Ian M Gould 3 1
Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom 2 Scottish MRSA Reference Laboratory, Microbiology Department, Stobhill Hospital, Glasgow, United Kingdom 3 Department of Medical Microbiology, Aberdeen Royal Infirmary, Aberdeen, United Kingdom
Introduction Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of hospital-acquired infections which is often endemic on intensive care units (ICU) in the UK. Critically ill patients are at high risk of developing MRSA associated bacteraemia with a high mortality rate. MRSA strains are primarily transmitted through staff and the environment between the ICU patients. Up to 75% decrease in the rate of MRSA acquisition was reported after improved environmental hygiene in a UK ICU. Several typing methods have been used to study MRSA surveillance and epidemiology, e.g. multilocus sequence typing (MLST), pulse-field gel electrophoresis (PFGE) and spa-typing. MLST is based on the nucleotide sequences of the fragments of seven housekeeping genes and is best suited to study long term evolution. PFGE and spa-typing offer higher strain resolution and are preferred over MLST to study local epidemiology. In this study, we investigated the local epidemiology in the ICU of Aberdeen Royal Infirmary by characterizing 53 MRSA isolates collected from patients between 2003-2007, using MLST, PFGE, spa-typing and antibiotic susceptibility typing.
Scientific findings MLST identified 7 sequence types (STs), of which three were novel. However, majority of isolates fell into ST22 belonging to clonal complex (CC)-22 (43.3%), ST36 (CC30; 22.6%) and ST45 (CC45; 24.5%). spa-types t032, t018 and t344 were predominant within CC22, CC30 and CC45, respectively. Most isolates in CC22 and CC30 had closely related PFGE profiles known to be associated with EMRSA-15 and EMRSA16, respectively. Similarly, CC45 isolates were closely related according to PFGE profiles, which were not common elsewhere in Scotland. Three resistance profiles were prevalent within CC20 whereas most isolates in CC30 and CC45 (71-85%) exhibited one CC-specific antibiogram.
Discussion P. jirovecii real-time PCR is useful in the diagnosis of PCP and sequence based genotyping may help identify environmental sources in the outbreak situation.
Previous reports suggested that EMRSA-15 and EMRSA-16 strains are usually prevalent in hospital-settings in the UK.
Abstracts
e39
Of those 45% were ESBL’s, 51% AmpC’s, 2% ESBL’s and AmpC’s and 2% inducible AmpC’s. The age range was from 3 months - 100 years. 77% of the isolates were community versus 23% from in-patients. Four antibiotic susceptibilities were analysed for resistant patterns. The study found trimethoprim to have the highest resistance of 53% and gentamicin the lowest at 32%, with nitrofurantoin and ciprofloxacin 43% and 40% respectively. 9% were resistant to all four antibiotics.
In agreement with these studies, these two clones were also responsible for majority of infection in the ICU wards of the Aberdeen Royal Infirmary. We also report the prevalence of a third clone, CC45 which has not yet been reported in healthcare settings in Scotland. We also observed an association between CCs and antimicrobial susceptibility profiles. PFGE and spa-typing provided higher strain discrimination than MLST. However, PFGE profiles were closely related within a CC and most isolates belonged to a single CC-specific spa-type.
Conclusions These results suggest persistence of three major MRSA clones within the ICU of Aberdeen Royal Infirmary. This is the first study characterizing MRSA in a Scottish ICU and will facilitate future MRSA surveillance and epidemiological investigations in healthcare settings in Scotland.
EVALUATION OF THE PREVALENCE AND ANTIBIOTIC SUSCEPTIBILITIES OF ESBL, AMPC AND INDUCIBLE AMPC’S AMONG URINARY ISOLATESCATEGORY: SCIENTIFIC FREE PAPER
Discussion The prevalence of ESBL and AmpC producing organisms is likely to increase with the majority of isolates coming from community patients. The possible oral antibiotic choices to treat ESBLs and AmpC’s are fast running out with the resistance to nitrofurantoin and trimethoprim at a high rate. Symptomatic urosepsis infections are admitted for I.V Meropenem and more worryingly 9% of the isolates tested also required treatment with Meropenem. The increase in the gentamicin resistance is disturbing as it is the empiric choice to cover resistant Gram negatives in patients with no previous ESBL or AmpC isolates.
Rebecca Turner, Deborah Gnanarajah Royal Derby Hospitals, Derby, United Kingdom
Introduction Extended Spectrum Beta-Lactamases (ESBL) and AmpC Beta-Lactamase (AmpC) producing coliforms are increasing in number, especially among the urine isolates, reducing the possible oral options available for treatment. Currently all new isolates have a full Vitek2Ò identification and sensitivity to ascertain their resistance pattern and also a 5 disc diffusion method for identification of their resistance mechanism. Objectives: To calculate the prevalence of ESBL, AmpC and inducible AmpC producing organisms over a 3 month period. To analysis the sensitivity rates of trimethoprim, nitrofuratoin, gentamicin and ciprofloxacin among urine isolates over a 3 month period. Method: A retrospective analysis of all urine isolates was carried out at the Microbiology Department, Royal Derby Hospital from Dec 2009 - Feb 2010. ESBL, AmpC and Inducible AmpC’s were identified using the 5 disc diffusion method of cefpodoxime +/- clavulanic acid, and cefepime +/- clavulanic acid for ESBL and AmpC detection and cefoxitin for inducible AmpC detection. Samples from the same patient within this period were considered to be duplicates and excluded.
Scientific findings Total number of urines received was 29,780, of which 6074 were positive & of those 217 were found to isolate an ESBL, AmpC or Inducible AmpC.
Conclusions Increased age, catheters and previous isolation of a multiresistant organism are clinical risk factors for acquiring urinary infections, which is supported by the average age of the study and 9% having a previous isolate. Treatment options are becoming limited as the organisms become more resistant to antibiotics.
IS FRAXÒ A VALID SCREENING TOOL FOR FRAGILITY FRACTURE RISK ASSESSMENT IN HIVPOSITIVE INDIVIDUALS?CATEGORY: SCIENTIFIC FREE PAPER Ben Stone 1, Eugene McCloskey 2, Christine Bowman 3, David Dockrell
4
1
Department of Infection and Tropical Medicine, Sheffield Teaching Hospitals, Sheffield, United Kingdom 2 Academic Unit of Bone Metabolism, The University of Sheffield, Sheffield, United Kingdom 3 Department of Genitourinary Medicine, Sheffield Teaching Hospitals, Sheffield, United Kingdom 4 Department of Infection and Immunity, The University of Sheffield, United Kingdom
Introduction The prevalence of reduced bone mineral density (BMD) and probably also fracture incidence are increased in HIVpositive individuals compared to HIV-negative controls. There are many potential explanations for this - an
Introduction Pneumocystis jirovecii is ubiquitous in the environment and an opportunistic pathogen which causes pneumonia in high risk patient groups e.g. immunocompromised patients, especially those with HIV, leukaemia and transplant patients. P. jirovecii pneumonia (PCP) has typically been diagnosed by a combination of immunofluorescence (IF) testing in the diagnostic laboratory and the clinical picture in the patient. However, IF despite having a good positive predictive value is an insensitive method. Increasingly molecular methods such as PCR are being used in the diagnosis of PCP. We describe the evaluation of a novel internally controlled real-time PCR, targeting the ß-tubulin gene for the diagnosis of PCP in induced sputum or broncheoalveolar lavage fluid. Also, in response to an outbreak of PCP cases in renal transplant patients at the Royal Liverpool University Hospital, genotypic sequencing (two gene fragments) of real-time PCR positive samples was undertaken. To determine the epidemiology, cases were compared with non-renal transplant controls. Both methods were adapted for testing of environmental (air and hard surface) sampling for P. jirovecii to investigate a common infection source.
Scientific findings The P. jirovecii real-time PCR has a detection limit of 350 gene copies/mL and 100% specificity. All IF positive samples and an additional fourteen samples that were IF negative were positive by real-time PCR. Of the renal transplant outbreak cases, samples were available from 18 and of these 17 were real-time PCR positive. Fourteen of 17 patients assessed shared the same genotype which was different from the non-renal controls. Environmental sampling detected P. jirovecii in the air and on surfaces and these strains comprised multiple genotypes including the one which predominated in the outbreak.
Discussion P. jirovecii real-time PCR improved the laboratory diagnosis of PCP compared with IF. Sequencing based genotyping showed that a common genotype predominated in the outbreak cases. In addition, environmental sampling detected P. jirovecii in clinical areas where patients had been. These findings influenced clinical management of patients through the extension of prophylaxis. The mode of transmission in the outbreak is still not clear. However, detection of P. jirovecii of the predominating genotype in the air cannot rule out the environment as a source.
Conclusions
Abstracts
MOLECULAR CHARACTERIZATION OF METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS FROM INTENSIVE CARE UNIT IN ABERDEEN ROYAL INFIRMARY, SCOTLANDCATEGORY: LESSON IN MICROBIOLOGY & INFECTION CONTROL Vartul Sangal 1, Kirsty Girvan 2, Sagar Jadhav 1, Leila Vali 1, Giles FS Edwards 2, Jun Yu 1, Ian M Gould 3 1
Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom 2 Scottish MRSA Reference Laboratory, Microbiology Department, Stobhill Hospital, Glasgow, United Kingdom 3 Department of Medical Microbiology, Aberdeen Royal Infirmary, Aberdeen, United Kingdom
Introduction Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of hospital-acquired infections which is often endemic on intensive care units (ICU) in the UK. Critically ill patients are at high risk of developing MRSA associated bacteraemia with a high mortality rate. MRSA strains are primarily transmitted through staff and the environment between the ICU patients. Up to 75% decrease in the rate of MRSA acquisition was reported after improved environmental hygiene in a UK ICU. Several typing methods have been used to study MRSA surveillance and epidemiology, e.g. multilocus sequence typing (MLST), pulse-field gel electrophoresis (PFGE) and spa-typing. MLST is based on the nucleotide sequences of the fragments of seven housekeeping genes and is best suited to study long term evolution. PFGE and spa-typing offer higher strain resolution and are preferred over MLST to study local epidemiology. In this study, we investigated the local epidemiology in the ICU of Aberdeen Royal Infirmary by characterizing 53 MRSA isolates collected from patients between 2003-2007, using MLST, PFGE, spa-typing and antibiotic susceptibility typing.
Scientific findings MLST identified 7 sequence types (STs), of which three were novel. However, majority of isolates fell into ST22 belonging to clonal complex (CC)-22 (43.3%), ST36 (CC30; 22.6%) and ST45 (CC45; 24.5%). spa-types t032, t018 and t344 were predominant within CC22, CC30 and CC45, respectively. Most isolates in CC22 and CC30 had closely related PFGE profiles known to be associated with EMRSA-15 and EMRSA16, respectively. Similarly, CC45 isolates were closely related according to PFGE profiles, which were not common elsewhere in Scotland. Three resistance profiles were prevalent within CC20 whereas most isolates in CC30 and CC45 (71-85%) exhibited one CC-specific antibiogram.
Discussion P. jirovecii real-time PCR is useful in the diagnosis of PCP and sequence based genotyping may help identify environmental sources in the outbreak situation.
Previous reports suggested that EMRSA-15 and EMRSA-16 strains are usually prevalent in hospital-settings in the UK.
Abstracts
e39
Of those 45% were ESBL’s, 51% AmpC’s, 2% ESBL’s and AmpC’s and 2% inducible AmpC’s. The age range was from 3 months - 100 years. 77% of the isolates were community versus 23% from in-patients. Four antibiotic susceptibilities were analysed for resistant patterns. The study found trimethoprim to have the highest resistance of 53% and gentamicin the lowest at 32%, with nitrofurantoin and ciprofloxacin 43% and 40% respectively. 9% were resistant to all four antibiotics.
In agreement with these studies, these two clones were also responsible for majority of infection in the ICU wards of the Aberdeen Royal Infirmary. We also report the prevalence of a third clone, CC45 which has not yet been reported in healthcare settings in Scotland. We also observed an association between CCs and antimicrobial susceptibility profiles. PFGE and spa-typing provided higher strain discrimination than MLST. However, PFGE profiles were closely related within a CC and most isolates belonged to a single CC-specific spa-type.
Conclusions These results suggest persistence of three major MRSA clones within the ICU of Aberdeen Royal Infirmary. This is the first study characterizing MRSA in a Scottish ICU and will facilitate future MRSA surveillance and epidemiological investigations in healthcare settings in Scotland.
EVALUATION OF THE PREVALENCE AND ANTIBIOTIC SUSCEPTIBILITIES OF ESBL, AMPC AND INDUCIBLE AMPC’S AMONG URINARY ISOLATESCATEGORY: SCIENTIFIC FREE PAPER
Discussion The prevalence of ESBL and AmpC producing organisms is likely to increase with the majority of isolates coming from community patients. The possible oral antibiotic choices to treat ESBLs and AmpC’s are fast running out with the resistance to nitrofurantoin and trimethoprim at a high rate. Symptomatic urosepsis infections are admitted for I.V Meropenem and more worryingly 9% of the isolates tested also required treatment with Meropenem. The increase in the gentamicin resistance is disturbing as it is the empiric choice to cover resistant Gram negatives in patients with no previous ESBL or AmpC isolates.
Rebecca Turner, Deborah Gnanarajah Royal Derby Hospitals, Derby, United Kingdom
Introduction Extended Spectrum Beta-Lactamases (ESBL) and AmpC Beta-Lactamase (AmpC) producing coliforms are increasing in number, especially among the urine isolates, reducing the possible oral options available for treatment. Currently all new isolates have a full Vitek2Ò identification and sensitivity to ascertain their resistance pattern and also a 5 disc diffusion method for identification of their resistance mechanism. Objectives: To calculate the prevalence of ESBL, AmpC and inducible AmpC producing organisms over a 3 month period. To analysis the sensitivity rates of trimethoprim, nitrofuratoin, gentamicin and ciprofloxacin among urine isolates over a 3 month period. Method: A retrospective analysis of all urine isolates was carried out at the Microbiology Department, Royal Derby Hospital from Dec 2009 - Feb 2010. ESBL, AmpC and Inducible AmpC’s were identified using the 5 disc diffusion method of cefpodoxime +/- clavulanic acid, and cefepime +/- clavulanic acid for ESBL and AmpC detection and cefoxitin for inducible AmpC detection. Samples from the same patient within this period were considered to be duplicates and excluded.
Scientific findings Total number of urines received was 29,780, of which 6074 were positive & of those 217 were found to isolate an ESBL, AmpC or Inducible AmpC.
Conclusions Increased age, catheters and previous isolation of a multiresistant organism are clinical risk factors for acquiring urinary infections, which is supported by the average age of the study and 9% having a previous isolate. Treatment options are becoming limited as the organisms become more resistant to antibiotics.
IS FRAXÒ A VALID SCREENING TOOL FOR FRAGILITY FRACTURE RISK ASSESSMENT IN HIVPOSITIVE INDIVIDUALS?CATEGORY: SCIENTIFIC FREE PAPER Ben Stone 1, Eugene McCloskey 2, Christine Bowman 3, David Dockrell
4
1
Department of Infection and Tropical Medicine, Sheffield Teaching Hospitals, Sheffield, United Kingdom 2 Academic Unit of Bone Metabolism, The University of Sheffield, Sheffield, United Kingdom 3 Department of Genitourinary Medicine, Sheffield Teaching Hospitals, Sheffield, United Kingdom 4 Department of Infection and Immunity, The University of Sheffield, United Kingdom
Introduction The prevalence of reduced bone mineral density (BMD) and probably also fracture incidence are increased in HIVpositive individuals compared to HIV-negative controls. There are many potential explanations for this - an