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1.  Pseudomonas aeruginosa Cystic Fibrosis isolates of similar RAPD genotype exhibit diversity in biofilm forming ability in vitro 
BMC Microbiology  2010;10:38.
Pseudomonas aeruginosa is considered to grow in a biofilm in cystic fibrosis (CF) chronic lung infections. Bacterial cell motility is one of the main factors that have been connected with P. aeruginosa adherence to both biotic and abiotic surfaces. In this investigation, we employed molecular and microscopic methods to determine the presence or absence of motility in P. aeruginosa CF isolates, and statistically correlated this with their biofilm forming ability in vitro.
Our investigations revealed a wide diversity in the production, architecture and control of biofilm formation. Of 96 isolates, 49% possessed swimming motility, 27% twitching and 52% swarming motility, while 47% were non-motile. Microtitre plate assays for biofilm formation showed a range of biofilm formation ability from biofilm deficient phenotypes to those that formed very thick biofilms. A comparison of the motility and adherence properties of individual strains demonstrated that the presence of swimming and twitching motility positively affected biofilm biomass. Crucially, however, motility was not an absolute requirement for biofilm formation, as 30 non-motile isolates actually formed thick biofilms, and three motile isolates that had both flagella and type IV pili attached only weakly. In addition, CLSM analysis showed that biofilm-forming strains of P. aeruginosa were in fact capable of entrapping non-biofilm forming strains, such that these 'non-biofilm forming' cells could be observed as part of the mature biofilm architecture.
Clinical isolates that do not produce biofilms in the laboratory must have the ability to survive in the patient lung. We propose that a synergy exists between isolates in vivo, which allows "non biofilm-forming" isolates to be incorporated into the biofilm. Therefore, there is the potential for strains that are apparently non-biofilm forming in vitro to participate in biofilm-mediated pathogenesis in the CF lung.
PMCID: PMC2841157  PMID: 20141637
2.  Identification and characterization of intervening sequences within 23S rRNA genes from more than 200 Campylobacter isolates from seven species including atypical campylobacters 
BMC Microbiology  2009;9:256.
Identification and characterization of intervening sequences (IVSs) within 23S rRNA genes from Campylobacter organisms including atypical campylobacters were carried out using two PCR primer pairs, designed to generate helix 25 and 45 regions.
Only C. sputorum biovar sputorum LMG7975 and fecalis LMG8531, LMG8534 and LMG6728 of a total of 204 Campylobacter isolates (n = 56 C. jejuni; n = 11 C. coli; n = 33 C. fetus; n = 43 C. upsaliensis; n = 30 C. hyointestinalis; n = 4 C. sputorum biovar sputorum; n = 5 C. sputorum biovar fecalis; n = 5 C. sputorum biovar paraureolyticus; n = 10 C. concisus; n = 7 C. curvus) were shown to carry IVSs in helix 25 region. C. sputorum biovar fecalis LMG8531 and LMG8534, interestingly, carried two different kinds of the 23S rRNA genes with and without the IVS, respectively. Consequently, in a total of 265 isolates of 269, including 65 C. lari isolates examined previously, the absence of IVSs was identified in the helix 25 region. In the helix 45 region, all the C. hyointestinalis, C. sputorum and C. concisus isolates were shown not to carry any IVSs. However, the 30 of 56 C. jejuni isolates (54%), 5 of 11 C. coli (45%), 25 of 33 C. fetus (76%), 30 of 43 C. upsaliensis (70%) and 6 of 7 C. curvus (90%) were shown to carry IVSs. In C. jejuni and C. upsaliensis isolates, two different kinds of the 23S rRNA genes were also identified to occur with and without IVSs in the helix 45 region, respectively.
Secondary structure models were also constructed with all the IVSs identified in the present study. In the purified RNA fractions from the isolates which carried the 16S or 23S rRNA genes with the IVSs, no 16S or 23S rRNA was evident, respectively.
PMCID: PMC2801512  PMID: 20003340
3.  Structural analysis of the full-length gene encoding a fibronectin-binding-like protein (CadF) and its adjacent genetic loci within Campylobacter lari 
BMC Microbiology  2009;9:192.
The combined sequences encoding a partial and putative rpsI open reading frame (ORF), non-coding (NC) region, a putative ORF for the Campylobacter adhesin to fibronectin-like protein (cadF), a putative Cla_0387 ORF, NC region and a partial and putative Cla_0388 ORF, were identified in 16 Campylobacter lari isolates, using two novel degenerate primer pairs. Probable consensus sequence at the -35 and -10 regions were identified in all C. lari isolates, as a promoter.
Thus, cadF (-like) gene is highly conserved among C. lari organisms. Transcription of the cadF (-like) gene in C. lari cells in vivo was also confirmed and the transcription initiation site was determined. A peptidoglycan-associating alpha-helical motif in the C-terminal regions of some bacterial cell-surface proteins was completely conserved amongst the putative cadF (-like) ORFs from the C. lari isolates.
The putative cadF (-like) ORFs from all C. lari isolates were nine amino acid larger than those from C. jejuni, and showed amino acid residues 137 -140 of FALG (50% identity), instead of the FRLS residues of the maximal fibronectin-binding activity site demonstrated within C. jejuni CadF. A neighbor joining tree constructed based on cadF (-like) gene sequence information formed a major cluster consisting of C. lari isolates, separating from the other three thermophilic campylobacters.
PMCID: PMC2751783  PMID: 19737389
4.  An optimised recovery method for thermophilic Campylobacter from liver 
BMC Microbiology  2001;1:32.
The past three decades have witnessed the rise of Campylobacter enteritis in man from virtual obscurity to notoriety, with present isolation rates superseding those of other enteric pathogens such as Salmonella spp. and Shigella spp. in most developed countries. Although campylobacters are not completely new to applied bacteriology, they have evaded traditional isolation techniques used for the isolation of pure cultures, apart from single isolations that were free from competing organisms. Offals, in particular liver have been decribed as both a source of campylobacters, as well as a route of transmission of this organism to human. Therefore, the aim of this study was to develop an optimum method for the recovery of Campylobacter spp. from porcine liver.
Four isolation techniques (methods A-D) were compared in a small pilot study for their ability to successfully recover campylobacters from freshly eviscerated porcine liver. The optimum isolation method involved direct swabbing of the liver tissues followed by plating onto Preston Selective medium, which was superior to methods involving mechanical disruption to liver tissues, including direct plating and enrichment methods, with and without blood. Consequently, any isolation method that involves disruption of liver tissue e.g. homogenisation or stomaching, is not suitable for the detection of campylobacters from liver and hence it is recommended that employment of a direct swabbing technique without mechanical disruption of tissues in combination with selective plating to optimally recover campylobacters from freshly eviscerated liver.
Employment of a direct swabbing technique in combination with selective plating allow Campylobacter spp. to be optimally recovered from freshly eviscerated liver and therefore this technique is recommended when examining liver for the presence of this organism.
PMCID: PMC61043  PMID: 11741507
5.  Phenotyping of Campylobacter jejuni and Campylobacter coli by a quantitative antibiogram [MIC] typing scheme using Euclidean distances [QATED] 
BMC Microbiology  2001;1:13.
Enteropathogenic Campylobacter jejuni and C. coli are presently the most common cause of acute bacterial gastroenteritis in the developed world. An understanding of sources and means of transmission of Campylobacter is an essential factor in order to reduce the incidence of Campylobacter-related gastroenteritis in man. Consequently a reproducible, sensitive and well-standardised typing scheme is critical in the successful discrimination of strains and in the subsequent investigations of outbreaks. For this purpose, a phenotypic typing scheme based on quantitative antibiogram determination based on Euclidean distance (QATED), was developed.
Results and Conclusion
The results obtained with this typing scheme demonstrated that individual livers of colonized pigs could be infected with multiple strains of Campylobacter spp. and subspecies types. In conclusion, phenotyping of Campylobacter jejuni and C. coli by QATED is a simple, inexpensive and discriminatory sub-species characterisation scheme, which may be useful in primary diagnostic clinical laboratories, where no specialist Campylobacter phenotyping or molecular genotyping schemes exist. It is especially suitable for food-bome outbreak investigations in the community, where a rapid and local response is required to aid with public health epidemiological investigations.
PMCID: PMC45583  PMID: 11527505

Results 1-5 (5)