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.

Antibacterial effects on acinetobacter species of commonly employed antineoplastic agents used in the treatment of haematological malignancies: an in vitro laboratory evaluation.

Although about 75-80% of neutropenic fevers are thought to be caused by infections, a causal organism can be confirmed microbiologically or suspected clinically in only 30-50%, and even fewer of these cases (16%) have a documented bacteraemia. The cause of neutropenic fever in the remaining cases remains elusive. The reasons for this failure may be due to the difficulty in recovering low numbers of organisms, fastidious organisms which fail to grow using conventional culture media, the presence of non-culturable organisms, or the presence of inhibitory substances in specimens. Previously, the authors showed the presence of Acinetobacter in peripheral blood of febrile neutropenic patients with a haematological malignancy, using 16S rDNA polymerase chain reaction (PCR) and sequencing techniques. However, conventional culture was unable to detect these organisms. Hence, it was felt necessary to examine the antibacterial properties of four antineoplastic agents used in the treatment of haematological malignancy, namely bleomycin, cisplatin, doxorubicin and vincristine. A total of 56 wild-type Acinetobacter including seven species (A. calcoaceticus [n=17], A. septicus [n=11], A. baumannii [n=10], A. johnsonii [n=7], A. lwoffii [n=8] A. haemolyticus [n=2] and A. radioresistens [n=1]) were examined for their susceptibility to the four antineoplastic agents at therapeutic concentration. No inhibition was observed, but inhibition was seen at higher concentrations of both bleomycin and doxorubicin. Time to detection of blood culture bottles containing separate antineoplastic agents (i.e., bleomycin and doxorubicin) was compared to that containing saline using a paired t-test. Samples containing doxorubicin at 1 pg/mL were shown to have a mean time to detection of 21.8 h (range: 15.6-31.4 h). Bottles containing saline had a mean time to detection of 22.9 h (range: 18.2-31.3 h). Statistical analysis showed no significant difference (P=0.3361) between time to detection for blood culture bottles containing doxorubicin at achievable plasma concentration and corresponding negative controls. With regard to bleomycin (300 miu/mL), the mean time to detection was 27.29 h (range: 20.2-38.4 h) in the test bottles, with mean time to detection in the saline negative controls of 22.56 h (range: 17.0-30.1 h). Paired t-test gave P=0.000451, hence a significant difference in time to detection for blood cultures containing therapeutic levels of bleomycin. Overall, the antineoplastic agents vincristine, cisplatin or doxorubicin did not have any inhibitory effects on the Acinetobacter organisms examined. At worst, therapeutic concentrations of bleomycin may delay automated detection of an Acinetobacter bacteraemia by a mean time of 5.9 h.

No evidence of transmission of bacteria between reptiles and a CF patient--a case report of a young adult CF patient and reptiles.

A microbiological study was undertaken to assess the risk of infection to a CF patient from a collection of pet reptiles, particularly atypical mycobacteria. This study helped to verify that the reptiles under the care of the CF patient did not harbour bacterial organisms that would normally be pathogenic to CF patients. However, the chronic carriage of Pseudomonas aeruginosa and other pathogens in the CF patient may constitute a greater risk of infection to the animals being handled. Therefore, we recommend stringent infection control precautions by CF patients and their pets, particularly adherence to hand washing and disinfection, when handling the animals, their litter or when working with their immediate environment, to potentially minimize the spread of bacterial and other pathogens from animal to human and vice versa. Detailed risk assessments therefore need to be undertaken by clinicians and veterinarians to detail working models that protect both animals and patients from pathogens originating from the other.

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.

Investigation of an outbreak of Salmonella enterica serovar Newport infection.

A large outbreak of Salmonella enterica serotype Newport infection occurred in Northern Ireland during September and October 2004. Typing of isolates from patients confirmed that this strain was indistinguishable from that in concurrent outbreaks in regions of England, in Scotland and in the Isle of Man. A total of 130 cases were distributed unequally across local government district areas in Northern Ireland. The epidemic curve suggested a continued exposure over about 4 weeks. A matched case-control study of 23 cases and 39 controls found a statistically significant association with a history of having eaten lettuce in a meal outside the home and being a case (odds ratio 23.7, 95% confidence interval 1.4-404.3). This exposure was reported by 57% of cases. Although over 300 food samples were tested, none yielded any Salmonella spp. Complexity and limited traceability in salad vegetable distribution hindered further investigation of the ultimate source of the outbreak.

Evaluation of the VITEK 2 AST N-054 test card for the detection of extended-spectrum beta-lactamase production in Escherichia coli with CTX-M phenotypes.

OBJECTIVES: A new VITEK 2 antibiotic susceptibility testing (AST) card, AST N-054, was introduced for aerobic gram-negative bacilli in 2007 and has been widely adopted for routine use in the UK. We evaluated its performance for detecting extended-spectrum beta-lactamase (ESBL) production in Escherichia coli. METHODS: ESBL-producing faecal isolates of E. coli (n = 137) from residents in nursing homes were tested using the AST N-054 card on VITEK 2 and with MASTDISCS ID ESBL detection disc diffusion tests (Mast Diagnostics, Bootle, UK). The susceptibility result recommended by the VITEK 2 software was also recorded. RESULTS: The AST N-054 card detected ESBL production in 93 of the 137 isolates tested [test sensitivity 67.9% (95% CI, 59.7-75.1)]. E. coli strain A, a widespread lineage in the UK with a low-level CTX-M enzyme production, accounted for most of the detection failures, with 35/73 strain A isolates incorrectly reported versus 9/64 non-strain A isolates (P < 0.0001). The MASTDISCS correctly detected ESBL in 135/137 isolates [test sensitivity 98.5% (95% CI, 94.5-99.9)]. Of the 44 isolates found to be negative for ESBL production by VITEK 2, the Advanced Expert System misreported 29 as susceptible to cefotaxime and all as susceptible to ceftazidime and aztreonam. CONCLUSIONS: These data suggest that the AST N-054 card for the VITEK 2 system is less reliable than other previously reported cards for the detection of CTX-M beta-lactamase-producing E. coli circulating in the UK, particularly strain A isolates.

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.

Food-poisoning and commercial air travel.

With the introduction of budget airlines and greater competitiveness amongst all airlines, air travel has now become an extremely popular form of travel, presenting its own unique set of risks from food poisoning. Foodborne illness associated with air travel is quite uncommon in the modern era. However, when it occurs, it may have serious implications for passengers and when crew are affected, has the potential to threaten safety. Quality, safe, in-flight catering relies on high standards of food preparation and storage; this applies at the airport kitchens (or at subcontractors' facilities), on the aircraft and in the transportation vehicles which carry the food from the ground source to the aircraft. This is especially challenging in certain countries. Several foodborne outbreaks have been recorded by the airline industry as a result of a number of different failures of these systems. These have provided an opportunity to learn from past mistakes and current practice has, therefore, reached such a standard so as to minimise risk of failures of this kind. This review examines: (i) the origin of food safety in modern commercial aviation; (ii) outbreaks which have occurred previously relating to aviation travel; (iii) the microbiological quality of food and water on board commercial aircraft; and (iv) how Hazard Analysis Critical Control Points may be employed to maintain food safety in aviation travel.

Development of a genus-specific PCR assay for the molecular detection, confirmation and identification of Fusobacterium spp.

A genus-specific polymerase chain reaction (PCR)-based assay is developed for the detection and identification of clinically relevant Fusobacterium species, including F. nucleatum and F. necrophorum. Two 16S ribosomal DNA (rDNA) primers, FUSO1 (forward primer: 5'-GAG AGA GCT TTG CGT CC-3' [17-mer]) and FUSO 2 (reverse primer: 5'-TGG GCG CTG AGG TTC GAC -3' [18-mer]) are designed to target conserved regions of the 16S rDNA gene for Fusobacterium spp. Subsequent proof-of-principle studies employing this assay detected Fusobacterium spp. in the faeces of eight (10%) out of 80 patients with suspected gastrointestinal infection. This assay may be used for the genus-specific detection of Fusobacterium spp. from clinical specimens and for subsequent species identification.

Cryptosporidium.

This review discusses characteristics of the genus Cryptosporidium and addresses the pathogenesis, reservoirs, public health significance and current applications for the detection and typing of this important pathogen. By increasing knowledge in key areas of Cryptosporidium research such as aetiology, epidemiology, transmission and host interactions, the numbers of cases of human cryptosporidiosis should be reduced.