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A M Kearns

Publications and source records attributed to A M Kearns.

At least 19 recordsLinked to original sources
PubMed2006

Community-associated meticillin-resistant Staphylococcus aureus: nosocomial transmission in a neonatal unit.

Community-associated meticillin-resistant Staphylococcus aureus (CA-MRSA) is an emerging pathogen, increasingly reported worldwide to cause infections in individuals without classical risk factors for acquiring healthcare-associated MRSA (HA-MRSA). This report describes the first documented transmission of CA-MRSA in a healthcare setting in the UK, involving four babies and a member of staff in a neonatal unit. Detailed microbiological characterization of the isolates revealed that they represented a single clone with the following characteristics: multi-locus sequence type (MLST) 1; staphylococcal cassette chromosome mec (SCCmec) type IVa; protein A (spa) type t127; agr group 3, and encoding enterotoxins A and H. The Panton-Valentine leukocidin genes were not detected. The CA-MRSA strain appeared to be circulating alongside several subtypes of epidemic MRSA-15, the most prevalent HA-MRSA in the UK. A combination of infection control measures contained the outbreak. This report highlights the changing epidemiology of MRSA in the UK, and emphasizes the need for healthcare personnel to be alert to the fact that CA-MRSA can occur not only in the community but also in the healthcare setting.

Community-Acquired Infections↗
PubMed2006

High interlaboratory reproducibility of DNA sequence-based typing of bacteria in a multicenter study.

Current DNA amplification-based typing methods for bacterial pathogens often lack interlaboratory reproducibility. In this international study, DNA sequence-based typing of the Staphylococcus aureus protein A gene (spa, 110 to 422 bp) showed 100% intra- and interlaboratory reproducibility without extensive harmonization of protocols for 30 blind-coded S. aureus DNA samples sent to 10 laboratories. Specialized software for automated sequence analysis ensured a common typing nomenclature.

Bacterial Typing Techniques↗
PubMed2005

Staphylococcus aureus isolates carrying Panton-Valentine leucocidin genes in England and Wales: frequency, characterization, and association with clinical disease.

Staphylococcus aureus isolates carrying the genes that encode for Panton-Valentine leucocidin (PVL), a highly potent toxin, have been responsible for recent outbreaks of severe invasive disease in previously healthy children and adults in the United States of America and Europe. To determine the frequency of PVL-positive isolates sent to the Staphylococcus Reference Unit (United Kingdom) for epidemiological purposes, we tested 515 isolates of S. aureus, and 8 (1.6%) were positive for the PVL locus. A further 470 isolates were selected to explore the association of PVL-positive S. aureus with clinical disease. Of these, 23 (4.9%) were PVL positive and most were associated with skin and soft tissue infections (especially abscesses). The PVL genes were also detected in isolates responsible for community-acquired pneumonia, burn infections, bacteremia, and scalded skin syndrome. Genotyping by pulsed-field gel electrophoresis and multilocus sequence typing revealed that the PVL-positive isolates were from diverse genetic backgrounds, although one prevalent clone of 12 geographically dispersed methicillin-resistant S. aureus (MRSA) isolates was identified (ST80). All 12 isolates were stapylococcal cassette chromosome mec type IVc, had an agr3 allele, and shared a common toxin gene profile (sea-see, seg-sej, eta, etb, and tst negative but etd positive). ST80 strains with similar genetic characteristics have been responsible for community-acquired infections in France and Switzerland. The remaining PVL-positive isolates were mostly methicillin-sensitive S. aureus and belonged to 12 different sequence types, including ST22 and ST30, which are closely related to the most prevalent MRSA clones in United Kingdom hospitals, EMRSA-15 and EMRSA-16, respectively.

Bacterial Toxins↗
PubMed2004

Survey, characterization and susceptibility to fusidic acid of Staphylococcus aureus in the Carmarthen area.

OBJECTIVE: This retrospective study was designed to investigate the possible reasons for an apparent increase in fusidic acid resistance among Staphylococcus aureus. MATERIALS AND METHODS: The Datastore records of the Communicable Disease Surveillance Centre, Wales, UK were reviewed in conjunction with information concerning the prescribing of fusidic acid. RESULTS: During the 5 year study period (1997-2001), a rise in the incidence of fusidic acid resistance was noted, particularly among paediatric patients presenting with infected eczema and impetigo, which may be related to the observed increase in prescriptions of topical fusidic acid. Extended phenotypic and genotypic characterization of a limited number (n=31) of isolates from 2002 showed that fusidic acid-resistant strains of S. aureus were typically from patients with impetigo and isolates fell into a single clonal group. Conversely, isolates from other skin disease (eczema, dermatitis and abscesses) were usually susceptible to fusidic acid and proved a diverse group. CONCLUSION: This study provides valuable data on the prevalence of fusidic acid-resistant S. aureus, the genetic background of the strains, and their association with clinical disease in both the healthcare environment and community setting in the catchment area served by the Laboratory.

Adolescent↗
PubMed2004

Clinical features, aetiology and outcome of empyema in children in the north east of England.

BACKGROUND: The incidence of empyema in children in the UK is increasing. The reason for this is unclear. A prospective study was undertaken to investigate the clinical features, aetiology, and outcome of cases of empyema and parapneumonic effusion presenting to a tertiary paediatric respiratory centre between February 1997 and August 2001. METHOD: Routine bacterial culture of blood and pleural fluid was performed for 47 cases. Forty three pleural fluid specimens, culture negative for pneumococcus, were analysed for pneumococccal DNA by real time polymerase chain reaction (PCR). Penicillin susceptibility was determined for DNA positive specimens using complementary PCR assay. Capsular serotype specific antigen detection was by enzyme immunoassay (EIA) using monoclonal antibodies to serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F. Clinical data were obtained from patient notes, supplemented by a postal questionnaire. RESULTS: The median (range) age of the patients was 5.6 (0.6-16.9) years and 70% were male. The median (range) duration of illness before referral to hospital was 5 (0-25) days. Forty five (96%) had received antibiotics before referral; 32 (68%) required decortication and eight (21%) thoracocentesis. Median postoperative stay was 4 days (2-8). Thirty two (75%) pneumococcal culture negative specimens were pneumococcal DNA positive; 17 (53%) of these were serotype 1. All were penicillin sensitive. CONCLUSIONS: Pneumococcus is the major pathogen in childhood empyema and serotype 1 is the prevalent serotype. This has implications for vaccine development and immunisation strategy as the current 7-valent pneumococcal conjugate vaccine does not protect against serotype 1.

Adolescent↗
PubMed2003

Diagnosis of invasive pneumococcal infection by PCR amplification of Streptococcus pneumoniae genomic fragments in blood: a multi-centre comparative study.

The increasing interest in the prevention of pneumococcal disease by immunisation necessitates improved organism-specific surveillance. This is particularly the case with regard to the contribution of Streptococcus pneumoniae infection to community-acquired pneumonia where blood cultures are often negative and sputum culture results ambiguous. Examination by PCR of blood samples taken at hospital admission offers one possibility for such improvement. The sensitivity, specificity and convenience of three pneumolysin gene PCR assays were compared in a large study, using EDTA blood from 175 patients (95 with proven pneumococcal bacteraemia, 80 with bacteraemia due to other organisms). The assays used were a PCR-enzyme immunoassay, a hybridisation probe assay run on the Roche LightCycler and a hydrolysis probe (TaqMan) assay run on an ABI 7700. Overall samples from only 57% of patients with bacteraemic pneumococcal infection yielded a positive result in at least one assay. Individual sensitivities ranged from 45% (TaqMan/ABI) through 35% (PCR-EIA) to 21% (Hybridisation/LightCycler). Specificity (PCR negative in the 80 control patients) ranged from 97-100%. The TaqMan/ABI assay was run in two centres and concordance between results was 91.4%, discrepancies being associated with very weakly positive samples. Overall, the TaqMan/ABI was the most sensitive and convenient assay; however, this method does not appear to offer any significant improvement over conventional blood cultures and is unlikely to be sufficiently sensitive to confirm a pneumococcal aetiology for non-bacteraemic pneumococcal pneumonia. For the present, therefore, blood culture is the preferred option.

Adolescent↗
PubMed2001

Development and evaluation of a real-time quantitative PCR for the detection of human cytomegalovirus.

A novel real-time quantitative PCR (QPCR) assay is described for monitoring CMV DNA load in clinical specimens using the LightCycler. The assay is rapid (< 40 min), easy to carry out, robust, reliable and is capable of detecting from 10 to over 2 x 10(5) CMV DNA copies with a wide linear range. Amplification and detection occur simultaneously, avoiding the need for post-PCR analysis and thereby minimising the risk of carryover contamination. The assay proved to be accurate, specific and reproducible when evaluated in three different laboratories. In addition, LightCycler results were comparable with those of TaqMan, an independent real-time QPCR assay.

Cytomegalovirus↗
PubMed2001

Tuberculosis transmitted through transplantation.

Tuberculosis in solid organ transplant recipients is associated with relatively high morbidity and mortality and is often extra-pulmonary. Reactivation of dormant infection is the usual mode of acquisition with donor and nosocomial transmission occurring infrequently. We report two cases of probable donor transmitted extra-pulmonary infection where both isolates of Mycobacterium tuberculosis proved to be indistinguishable using hemi-nested inverse PCR of the IS 6110 region.

Adult↗
PubMed2000

Comparison of PCR detection of mecA with methicillin and oxacillin disc susceptibility testing in coagulase-negative staphylococci.

The provisional BSAC method for the detection of methicillin sensitivity in coagulase-negative staphylococci (CNS) requires incubation of isolates for 48 h and raises the problem of timely reporting of susceptibility data. The forthcoming withdrawal of methicillin raises another difficulty. We evaluated 42 clinically significant CNS blood culture isolates by PCR, methicillin and oxacillin disc testing and by using methicillin Etests. Our results suggest that, although oxacillin disc susceptibility testing is a reasonable first line step, optimal and timely detection of resistance or susceptibility may require a combination of phenotypic and genotypic methods.

Coagulase↗
PubMed2000

Epidemiology and molecular typing of an outbreak of tuberculosis in a hostel for homeless men.

AIM: To investigate a possible outbreak of tuberculosis in a hostel for homeless men using IS6110 profiling, a polymerase chain reaction (PCR) based fingerprinting technique. METHODS: Eight cases of tuberculosis were diagnosed in residents of the hostel over a period of 28 months. To provide epidemiological data, a heminested inverse PCR (HIP) assay targeting the insertion sequence IS6110 together with its upstream flanking region was used to fingerprint the eight isolates of M tuberculosis under investigation. RESULTS: The HIP technique gave IS6110 profiles which showed that while three isolates were clearly distinct, the remaining five strains were indistinguishable, suggesting the latter were representatives of a single outbreak strain. CONCLUSIONS: The HIP assay proved discriminatory and facilitated repeated testing for the direct comparison of strains as more patients presented over the protracted course of this outbreak.

Adult↗
PubMed1999

Rapid detection of methicillin-resistant staphylococci by multiplex PCR.

A multiplex PCR was developed to detect the coagulase gene (coa; pathognomic of Staphylococcus aureus) and the mecA gene (characteristically encoding for methicillin resistance in staphylococci) in a single, rapid test. Suitable primers for the gene targets and an internal, amplification control were incorporated into a multiplex PCR assay, which was then optimized on a capillary air thermal cycler to improve the turnaround time of the test to approximately 1.5 hours. The assay was evaluated with 111 fresh clinical isolates of staphylococci. The multiplex PCR correctly distinguished between isolates of S. aureus, which were sensitive to methicillin (MSSA) and those resistant to it (MRSA). It also correctly differentiated between similar isolates of coagulase negative staphylococci (MSSE and MRSE respectively). It was concluded that this multiplex PCR was a rapid and reliable method for the detection of methicillin-resistant staphylococci.

Coagulase↗