Meningococcal Disease in Northern Ireland - Past, Present & Future: MeningoNI Forum

Meningococcal disease has had devastating consequences in Northern Ireland since its first description locally in 1859. The incidence of this disease has significantly declined in recent years, however it is important to understand reasons for this changing epidemiology and to acknowledge the diagnostic and clinical management developments that have been made locally. This review aims to examine the changing face of this disease in Northern Ireland over the years, with particular reference to local disease prevention, epidemiology, diagnosis, clinical treatment and management, post-disease sequelae and the role of meningitis charities locally, in terms of patient support and research.

Muddy puddles - the microbiology of puddles located outside tertiary university teaching hospitals

In the British Isles, the frequency of rain results in the formation of puddles on footpaths and roads in/around hospitals. No data are available demonstrating the microbiological composition of such puddles and therefore a study was undertaken to examine the microbiology of puddles in the grounds of two tertiary university-teaching hospitals (18 sites) and compared with control puddles from non-hospital rural environments (eight sites), estimating (i) total viable count; (ii) identification of organisms in puddles; (iii) enumeration of Escherichia coli: (iv) detection of Extended Spectrum β-Lactamase producing organisms and (v) direct antimicrobial susceptibility testing. A mean count of 2·3 × 10³  CFU per ml and 1·0 × 10⁹  CFU per ml was obtained for hospital and non-hospital puddles respectively. Isolates (n = 77; 54 hospital and 23 non-hospital) were isolated comprising of 23 species among 17 genera (hospital sites), where the majority (10/16; 62·5%) of genera identified were Gram-negative approximately, a fifth (20·6%) were shared by hospital and non-hospital rural samples. Escherichia coli was detected in half of the hospital puddles and under-half (37·5%) of the rural puddles extended spectrum β-lactamase organisms were not detected in any samples examined. Rainwater puddles from the hospital and non-hospital environments contain a diverse range of bacteria, which are capable of causing infections.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study demonstrated the presence of a wide diversity of bacterial taxa associated with rainwater puddles around hospitals, many of which are capable of causing human disease. Of clinical significance is the presence of Pseudomonas aeruginosa isolated from a hospital puddle, particularly for patients with cystic fibrosis. The presence of potentially disease-causing bacteria in puddles in and around hospitals identifies a new potential environmental reservoir of bacteria. Furthermore work is now needed to define their potential of entering or exiting hospital wards by contaminated footwear.

Comparison of antibiotic susceptibility in viridans group streptococci in low and high antibiotic-prescribing General Practices

WHAT IS KNOWN AND OBJECTIVE

Antibiotic resistance has become a global public health issue. Most antibiotics are prescribed in the community, although there is less stewardship of such agents in the community compared to secondary and tertiary care. Few studies have attempted to examine the prescribing practices in General Practice and its impact on antibiotic resistance and, therefore, a study was performed in order to compare antibiotic susceptibilities of commensal viridans group streptococci (VGS) obtained from patient cohorts in General Practices (GP), who were high and low prescribers of oral antibiotics.

METHOD

Sixty-five patients (<1 month-81 years; 77% female: 23% male) were enrolled onto the study, and viridans group streptococci (n = 5/patient) were collected from each patient's nasal passages and oropharynx region and tested for antibiotic susceptibility against (i) tetracyclines (doxycycline); (ii) macrolides (erythromycin); (iii) β-lactams (penicillin G); and (iv) fluoroquinolones (ofloxacin & levofloxacin).

RESULTS AND DISCUSSION

There were no significant differences in MICs between high and low GP prescribers with doxycycline (P = 0·094), erythromycin (P = 0·122), ofloxacin (P = 0·193) and levofloxacin (P = 0·058). However, there was a significant difference between high and low GP practices with regard to penicillin G (P = 0·031). This finding is important as the β-lactams are the most commonly prescribed oral antibiotic in the community.

WHAT IS NEW AND CONCLUSION

This study demonstrates that high prescribing practices may lead to an altered (higher) level of resistance to these agents in the commensal VGS population, which may be important as reservoirs of antibiotic resistance determinants in subsequent horizontal gene transfer events, particularly with newly colonizing pathogens, including pneumococci. Primary care physicians should be aware that increased prescribing of antibiotics may led to increased level of penicillin resistance.

Reliability of self-reporting of antibiotic consumption in the community - Index of Reliability

WHAT IS KNOWN AND OBJECTIVE

To date, there is no evidence to indicate the reliability of how patients self-report their own antibiotic usage in the community. Such data are fundamental in supporting antimicrobial stewardship practices, and so there is a need to determine its accuracy and reliability.

COMMENT

Patients in the community (n = 476) were required to recollect their antibiotic usage in the past three months. Simultaneously, similar information was obtained by careful extraction from their respective medical notes, which was qualitatively compared with the patient's recollection. Overall, concordance was high (88·1%), but age (<20 and >80 years) and sex (female) were significant factors of reliability.

WHAT IS NEW AND CONCLUSION

This study suggests that basic self-reporting of antibiotic usage amongst patients is relatively reliable, with increasing accuracy with years until 80 years. Where such information is critical, the current study can help decide who to interview and whose notes to interrogate, in the quest to obtain reliable and accurate information.

Comparasion of five gene loci (rnpB, 16S rRNA, 16S-23S rRNA, sodA and dnaJ) to aid the molecular identification of viridans-group streptococci and pneumococci

Viridans-group streptococci (VGS) consist of several taxa which historically have been highly diverse. However, at times it may become necessary to have a reliable scheme for the identification of these organisms to the species level. The aim of this study is to compare the ability of five gene loci, namely rnpB, 16S rRNA, 16S-23S rRNA, sodA and dnaJ, to speciate such organisms through a sequence typing-based approach. Reference organisms consisting of six VGS species were compared based on sequence typing, followed by comparison of 31 wild-type respiratory isolates, and showed that employment of sequence typing using the rnpB gene locus was the most specific and reliable. Therefore, the use of rnpB sequencing for the identification of VGS to species level is a reliable and feasible option, based on a single gene target.

Molecular characterisation of the quinolone resistance-determining regions (QRDR) including gyrA, gyrB, parC and parE genes in Streptococcus pneumoniae

Streptococcus pneumoniae is the leading cause of community-acquired pneumonia (CAP). Currently, empirical treatment with quinolones is being used due to the emergence of beta-lactam and macrolide resistance in S. pneumonaie. Although the prevalence of quinolone-resistant S. pneumoniae remains low, increasing numbers of resistant isolates are being seen. Genetic mechanisms leading to fluoroquinolone resistance in pneumococci are complex. This study aims to use molecular methods to characterise all isolates through sequence analysis of their QRDR regions. Thirty-two S. pneumoniae isolates were obtained from nasal swabs from adult and paediatric patients attending local general practices in Northern Ireland. Phenotypic minimum inhibitory concentration (MIC) was determined for Clinical and Laboratory Standards Institute (CLSI) broth microdilution against ciprofloxacin, levofloxacin and norfloxacin. Simultaneously, the QRDR regions of gyrA, gyrB, parC and parE were analysed by sequence typing for all pneumococci obtained. Only one isolate (3.1%) showed reduced susceptibility to ciprofloxacin and levofloxacin. Two amino acid positions were discordant in the S. pneumoniae R6 strain and eight (25%) and 23 (71.9%) isolates contained the mutations Ile460Val in gyrA and Lys137Asn in parC (deposited in GenBank, accession numbers GQ999587-GQ999589), respectively. No mutations were found in either the gyrB or parE loci. In conclusion, the study demonstrated increased fluoroquinolone resistance which could not be accounted for simply through QRDR mutations, and, reciprocally, that mutations in the QRDR region do not necessarily result in overt phenotypic resistance.

Exposure to clinical X-ray radiation does not alter antibiotic susceptibility or genotype profile in gram-negative and gram-positive clinical pathogens

Inadvertent exposure of bacterial pathogens to X-ray radiation may be an environmental stress, where the bacterium may respond by increasing mutational events, thereby potentially resulting in increased antibiotic resistance and alteration to genotypic profile. In order to examine this, four clinical pathogens, including the Gram-negative organisms Escherichia coli O157:H7 NCTC12900 and Pseudomonas aeruginosa NCTC10662, as well as the Gram-positive organisms Staphylococcus aureus NCTC6571 and Enterococcus faecium were exposed to X-rays (35,495 cGy/cm2) over a seven-day period. Antibiotic susceptibility was assessed before, during and after exposure by examining susceptibility, as quantified by E-test with six antibiotics, as well as to a further 11 antibiotics by measurement of susceptibility zone sizes (mm). Additionally, the DNA profile of each organism was compared before, during and after exposure employing the enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC PCR). Results indicated that exposure of these organisms to this amount of X-ray radiation did not alter their antibiotic susceptibility, nor their genomic DNA profile. Overall, these data indicate that exposure of bacteria to X-ray radiation does not alter the test organisms' antibiotic susceptibility profiles, nor alter genomic DNA profiles of bacteria, which therefore does not compromise molecular epidemiological tracking of bacteria within healthcare environments in which patients have been exposed to X-ray radiation.

Molecular characterisation of the quinolone resistance-determining region (QRDR) of the parC gene locus in viridans-group streptococci

Forty-eight isolates of viridans-group streptococci (VGS) from adults and children in the community are examined for their resistance to ciprofloxacin phenotypically by determination of the minimum inhibitory concentration (MIC). In addition, the parC gene locus is amplified and sequenced in all isolates and mutations noted. Overall, 44 VGS organisms were found to be susceptible to ciprofloxacin by the broth microdilution method, and the remaining four strains had intermediate susceptibility. Reduced MICs were observed with intermediate strains when reserpine was added to the broth, inhibiting any efflux activity. Overall, the effect of adding reserpine to the broth medium was to add one doubling dilution to the MIC in the case of Streptococcus mitis, S. oralis and S. salivarius, as well as to increase the MIC by two doubling dilutions in two of the three S. parasanguinis isolates. Amino acid sequence analysis of the quinolone resistance-determining region (QRDR) of the parC gene locus showed good correlation to the phenotypic resistance to ciprofloxacin, where no confirmed mutation conferring quinolone resistance was found. Eleven amino acid positions showed discordance with S. pneumoniae R6 and eight (S52, F55, S58, N91, E135, K137, F141 and S167) were common in the VGS species examined. In addition, minor substitutions were found at three positions (D51, T54 and V86). In conclusion, this study demonstrates the low occurrence of ciprofloxacin resistance in a population of VGS isolated from the community. In addition, several silent mutations were noted in VGS organisms without any increase in MIC against ciprofloxacin.

Prevalence of clustered regulatory interspaced short palindromic repeat (CRISPR)-like sequences in mitis-group streptococci

Clustered regulatory interspaced short palindromic repeats (CRISPRs) have been discovered in many bacteria and archaea. Many CRISPR-like sequences have been identified in an increasing number of studies on the function of CRISPRs. One CRISPR-like sequence of approximately 240 base pairs has been found to be highly conserved within 11 genome sequences of Streptococcus pneumoniae. A specific CRISPR-like polymerase chain reaction (PCR) assay was designed with the novel primers CRISPR 5F (forward primer) 5'-CTA ATY TCA TAA CCA TAR GAA TC-3' and CRISPR 3R (reverse primer) 5'-GAT AAR ATC CTY TAA WCT TCT AG-3' to detect the presence of this CRISPR-like sequence in pneumococci, as well as in viridans-group streptococci (VGS). This study investigates the prevalence of this CRISPR-like sequence in S. pneumoniae and 12 viridans-group streptococcal species and shows its existence to be shared by the majority of S. pneumoniae and, to a lesser extent, S. mitis. This CRISPR-like sequence was also found in S. australis and it is highly conserved among these strains, suggesting possible biological functional differences from true CRISPR because this CRISPR-like sequence has relatively few repeat numbers, and adjacent homology of CRISPR-associated (cas) genes was absent. The sharing of this CRISPR-like sequence between pneumococci, the mitis group and other VGS, as well as its high sequence homology, may suggest close evolutionary emergence of this sequence between these species.

Non-coding small (micro) RNAs of Pseudomonas aeruginosa isolated from clinical isolates from adult patients with cystic fibrosis

MicroRNAs are a class of small non-coding RNAs widely reported in eukaryotic multicellular organisms. In this study, a number of small non-coding micro (mi)RNA species in clinical isolates of prokaryote Pseudomonas aeruginosa were obtained from the sputum of adult patients with cystic fibrosis (CF) utilising a DynaExpress miRNA cloning kit, and five miRNAs of 16-47 nucleotides that were smaller than those encountered or described (80-100 nucleotides) previously in bacterial systems were described. This report presents data on these unknown cellular miRNAs cloned from P. aeruginosa isolates from CF patients. Adapting a computational miRNA prediction model that takes advantage of the highly conserved known miRNA hair pin stems regions, the results revealed that the fold structure of the microRNAs had a high homology to the recently reported human bacterial infection response (BiR)-related microRNA, mi-146, associated with the Toll-like receptor (TLR) family, which is the primary evolutionarily conserved sensors of pathogen-associated molecular patterns (PAMPs), and known to trigger host inflammatory and immune responses.

Optimisation of storage conditions for maintaining culturability of penicillin-susceptible and penicillin-resistant isolates of Streptococcus pneumoniae in transport medium

Methods employed by the World Health Organization (WHO) are used during this study to determine the optimum storage conditions for maintaining the culturability of Streptococcus pneumoniae in skimmed milk, tryptone, glucose and glycerin (STGG) transport medium. A comparison of S. pneumoniae strains sensitive and resistant to penicillin showed no significant difference in their survival ability in STGG medium. Furthermore, it is confirmed that storage at -70 degrees C remains most effective for maintaining viability by culture of S. pneumoniae. Storage at -20 degrees C would only be acceptable in the short-term, while storage at +4 degrees C is not recommended. Of note, this study has shown STGG medium at room temperature to be an efficient growth medium for pneumococci in the short-term. This work will help to establish robust sampling protocols when performing community studies to ensure culturability of comparison between community and laboratory pneumococci survival.

Molecular characterisation of the recA locus in clinical isolates of verocytotoxigenic E. coli O157:H7

Molecular epidemiology of verocytoxigenic Escherichia coli O157:H7 is important to help elucidate reservoirs and modes of transmission, particularly between animals and humans. As the recA gene locus is now beginning to gain application in bacterial genotyping schemes, and as it has not been examined previously in E. coli O157 isolates, this study aims to examine potential polymorphic variation as a possible epidemiological marker for the subspecies characterisation of clinically significant verocytotoxigenic E. coli O157:H7. A novel polymerase chain reaction (PCR) assay was designed to target a 638 bp region of the recA gene in E. coli O157 isolates. The PCR amplification of genomic DNA from extracted organisms was able to generate an amplicon of the expected size (approximately 638 bp) for all E. coli O157:H7 examined (n=80), as well as for other non-O157 E. coli and other members of the Enterobacteriaeceae including Citrobacter, Hafnia, Shigella, Enterobacter and Providencia. Subsequent restriction fragment length polymorphism (RFLP) and single-stranded conformational polymorphism (SSCP) analyses of these recA amplicons were able to differentiate E. coli O157 from the organisms examined, but were unable to distinguish between 79 isolates of wild-type E. coli O157, suggesting a highly conserved recA gene structure within the local population of organisms examined.

Molecular epidemiology of Pseudomonas aeruginosa in adult patients with cystic fibrosis in Northern Ireland

Isolates (n = 51) of Pseudomonas aeruginosa obtained from the sputa of 29 adult patients attending the Regional Cystic Fibrosis Centre in Northern Ireland were compared using an enterobacterial repetitive intergenic consensus sequence (ERIC2) primer in a random amplification of polymorphic DNA (RAPD) polymerase chain reaction (PCR) method. Resulting banding patterns showed a high degree of genetic heterogeneity among all isolates from the patients examined, suggesting a non-clonal relationship between isolates from these patients, when employing this genotyping technique.

Prevalence of gastrointestinal bacterial pathogens in a population of zoo animals

Faecal prevalence of gastrointestinal bacterial pathogens, including Campylobacter, Escherichia coli O157:H7, Salmonella, Shigella, Yersinia, as well as Arcobacter, were examined in 317 faecal specimens from 44 animal species in Belfast Zoological Gardens, during July-September 2006. Thermophilic campylobacters including Campylobacter jejuni, Campylobacter coli and Campylobacter lari, were the most frequently isolated pathogens, where members of this genus were isolated from 11 animal species (11 of 44; 25%). Yersinia spp. were isolated from seven animal species (seven of 44; 15.9%) and included, Yersinia enterocolitica (five of seven isolates; 71.4%) and one isolate each of Yersinia frederiksenii and Yersinia kristensenii. Only one isolate of Salmonella was obtained throughout the entire study, which was an isolate of Salmonella dublin (O 1,9,12: H g, p), originating from tiger faeces after enrichment. None of the animal species found in public contact areas of the zoo were positive for any gastrointestinal bacterial pathogens. Also, water from the lake in the centre of the grounds, was examined for the same bacterial pathogens and was found to contain C. jejuni. This study is the first report on the isolation of a number of important bacterial pathogens from a variety of novel host species, C. jejuni from the red kangaroo (Macropus rufus), C. lari from a maned wolf (Chrysocyon brachyurus), Y. kristensenii from a vicugna (Vicugna vicugna) and Y. enterocolitica from a maned wolf and red panda (Ailurus fulgens). In conclusion, this study demonstrated that the faeces of animals in public contact areas of the zoo were not positive for the bacterial gastrointestinal pathogens examined. This is reassuring for the public health of visitors, particularly children, who enjoy this educational and recreational resource.