e100 Abstracts

A STUDY OF THE VARIATION IN GENETICDIVERSITY OF HAEMOPHILUS INFLUENZAESEROTYPE B (HIB) STRAINS IN THE UK BETWEEN1987 AND 2010 USING MULTILOCUS VARIABLE-NUMBER TANDEM REPEAT ANALYSIS (MLVA)CATEGORY: LESSON IN MICROBIOLOGY &INFECTION CONTROL

Sapna Manglani, David Litt, Shona Neal, Mary SlackHealth Protection Agency, London, United Kingdom

Introduction

In 1992 theUKaddedHaemophilus influenzae serotypeb (Hib)vaccine to the infant immunisation schedule (at 2, 3, 4months), resulting in a dramatic decline in the incidence of in-vasive Hib disease. From 1999 there was a resurgence of inva-siveHibdisease in fully vaccinatedchildren,olderchildrenandadults, which has been controlled by the introduction in 2006of a routine booster dose of Hib vaccine at 12 months of age.Wehavecharacterisedover700Hib strains, collectedbetween1987 and 2010 from UK cases of invasive disease, using multi-locus variable-number tandem repeat analysis (MLVA). Thisenabledus to studychanges in thedistributionof clonal groupsin the bacterial population, and of overall genetic diversityover time and between different patient groups.

Scientific findings

Our results revealed an increase in genetic diversityamongst strains isolated from children in the post-vaccineperiod (after 1992) compared to the pre-vaccine period.The reverse, however, was observed for strains isolatedfrom adults. Nineteen MLVA types were only found in thepost-vaccine population (compared to the pre-vaccine andnon-vaccinated populations). Strains isolated from cere-brospinal fluid (CSF) demonstrated higher genetic diversitythan those isolated from blood, and 9 MLVA types wereunique to strains isolated from CSF. Strains also demon-strated increasing genetic diversity in the following order ofclinical presentation: septic arthritis, cellulitis, bacterae-mia, pneumonia, epiglottitis and meningitis.

Discussion

These results suggest that the introduction of Hib vaccineaffected patient age-groups differently. Various MLVAclonal groups may possess diverse virulence determinantsand pathogenic potential such as the MLVA types whichwere unique to strains isolated from CSF and the strainswhich demonstrated varying genetic diversity depending onclinical presentation. Important virulence genes need to beanalyzed to investigate this further.

Conclusions

The introduction of the Hib vaccine affected adult andpatient groups differently and nineteen MLVA types were

found to be unique to the post-vaccine population. A highergenetic diversity was found for strains isolated from CSFthan those isolated from blood and genetic diversity ofstrains varied with clinical presentation. The various MLVAclonal groups may possess diverse virulence determinantsand pathogenic potential.

BIOFILM FORMATION BY PROPIONIBACTERIUMACNES ISOLATED FROM DENTALHANDPIECESCATEGORY: LESSON INMICROBIOLOGY & INFECTION CONTROL

Gordon Smith, Gordon Ramage, Andrew SmithUniversity of Glasgow, Glasgow, United Kingdom

Introduction

Dental handpieces are complex, invasive, surgical instru-ments used for oral surgery. Through routine use handpie-ces are exposed internally and externally to contaminantsfrom the operating environment, including blood, bacteriaand human tissue. The potential exists for internal con-taminants to be released from the handpiece upon use andtherefore a cross contamination potential exists if thehandpiece is not decontaminated between patients. Duringmicrobial sampling of handpieces, Propionibacterium acneswas isolated from a number of surgical handpieces whichare used for more complex and invasive procedures. P.acnes has been isolated from the oral cavity and has previ-ously been associated with endocarditis and the infectionof prosthetic hip joints caused by passage in the bloodstream. Central to the pathology of this microorganism isthe ability to form biofilms on non shedding surfaces. Thisstudy aimed to assess the cross contamination risk from P.acnes in dental handpieces by studying the ability of eachisolate at forming biofilms in an in vitro model and to assessthe efficacy of biocides used in the decontamination ofhandpieces at disrupting these biofilms.

Scientific findings

P. acnes biofilms (n¼39) were formed anaerobically us-ing a bespoke assay system developed by our group. Thelevels of biofilm formation were assessed using a metabolicand biomass assay. The effect of biocides on biofilm disrup-tion was also assessed using a modification of CLSI method-ology. All P. acnes clinical isolates formed biofilms underanaerobic conditions equivalent to an established control.Commercially available biocides were shown to disrupt bio-films at varying levels (40-80%) but metabolically activecells were still present after exposure.

Discussion

Biofilms formed by P. acnes are an important reservoir ofinfection on dental handpieces. The ability to exist in this

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growth modlity provides protection from chemical disin-fection during the decontamination process. We haveshown that commercially available biocides are ineffectiveat both disruption of the biofilm and termination of viablecells. This has implications for the handpiece decontami-nation processes.

Conclusions

This study highlights the ubiquity of P. acnes within clinicalenvironments, and the ability of P. acnes to form biofilmsout with the host has implications for cross infection, par-ticularly given its association with chronic infections ofjoints and the bloodstream. Improved methods accountingfor P. acnes biofilms should be considered during the dentalhandpiece decontamination cycle.

TIMING OF ENTERAL FEEDING IN CEREBRALMALARIA IN RESOURCE-POOR SETTINGS: ARANDOMIZED TRIALCATEGORY: SCIENTIFIC FREEPAPER

Richard Maude 1,2, Md Gofranul Hoque 3, MdMahtab Uddin Hasan 3, MdAbu Sayeed 3, Shahena Akter 3, Rasheda Samad 3,Badrul Alam 3, Emran Bin Yunus 3, MdRidwanur Rahman 4, MdWaliur Rahman 3, Romal Chowdhury 3, Tapan Seal 3,Prakaykaew Charunwatthana 1, Christina Chang 1,Nicholas White 1,2, Md Abul Faiz 5, Nicholas Day 1,2,Arjen Dondorp 1,2, Md Amir Hossain 1

1Mahidol-Oxford Tropical Medicine Research Unit, Facultyof Tropical Medicine, Mahidol University, Bangkok,Thailand2Centre for Tropical Medicine, Nuffield Department ofClinical Medicine, John Radcliffe Hospital, University ofOxford, Oxford, United Kingdom3Chittagong Medical College Hospital, Chittagong,Bangladesh4Hossain Shahid Sohrawardy Medical College, Dhaka,Bangladesh5 Sir Salimullah Medical College, Dhaka, Bangladesh

Introduction

Early start of enteral feeding is an established treatmentstrategy in intubated patients in intensive care since itreduces invasive bacterial infections and length of hospitalstay. There is equipoise whether early enteral feeding isalso beneficial in non-intubated patients with cerebralmalaria in resource poor settings.

A randomized trial of early (day of admission) versus late(after 60 hours in adults or 36 hours in children) start ofenteral feeding was undertaken in patients with cerebralmalaria in Chittagong, Bangladesh.

Scientific findings

Thetrialwas terminatedafter inclusionof56patientsbecauseof a high incidence of aspiration pneumonia in the earlyfeeding group (9/27 (33%)), compared to the late feedinggroup (0/29 (0%)), p¼0.001). One patient in the late feedinggroup, and none in the early group, had hypoglycaemia duringadmission. There were no significant difference in overallmortality (9/27 (33%) vs 6/29 (21%), p¼0.370), but mortalitywas 5/9 (56%) in patients with aspiration pneumonia.

Discussion

This studyprovides strongevidence thatearly enteral feedingis detrimental in patients with cerebral malaria treated inresource poor settings where endotracheal intubation is notgenerally available. Early enteral feeding increases the risk ofaspiration pneumonia and conveys no clear benefits.

Conclusions

Early start of enteral feeding is detrimental in non-intubatedpatients with cerebral malaria in resource-poor settings.

EFFICACY OF THE BIOCIDE, STERI-7, AGAINSTCOMMON BACTERIAL PATHOGENS ASSOCIATEDWITH CYSTIC FIBROSIS (CF)CATEGORY: LESSON INMICROBIOLOGY & INFECTION CONTROL

John E Moore, JR RaoUniversity of Ulster, Coleraine, United Kingdom

Introduction

Cystic fibrosis (CF) is the most commonly inherited diseasein persons originating from a white and European back-ground and has a genetic carriage rate of 1 in 20 persons.The most common complication of CF is the recurrence ofchronic chest infections usually caused by bacterial path-ogens (e.g. Pseudomonas aeruginosa, Burkholderia cepaciacomplex and Stenotrophomonas maltophilia). It is thereforeimperative that stringent disinfection measures are takento prevent colonization of the lung with these and otherorganisms, both by the patient, as well as by the healthcare professional in conjunction with infection controlguidelines. Although combinational antibiotic therapy isthe cornerstone of the treatment of such infections, oncethe CF patienr has acquired them, high levels of resistancehave been described for Gram negativr CF organisms anddue diligence and utmost care is required to monitor andsanitize the healthcare environments

Scientific findings

Three formulations of Steri-7, (i) Steri-7 biocidal concen-trate, (ii) Steri-7 surface cleaner and (iii) Steri-7 hand