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Biomedical subjects

J R Kerr

Publications and source records attributed to J R Kerr.

At least 37 records · Page 2Linked to original sources
PubMed2001

Current pharmacotherapy of pertussis.

Human infection with Bordetella pertussis and Bordetella parapertussis causes significant morbidity and mortality. While universal immunisation represents the mainstay of prevention, the purpose of this review is to summarise the current options for antimicrobial chemotherapy of pertussis. Several chemotherapeutic approaches have an important place in therapy and in infection control. Supportive treatment including nasopharyngeal suction, oxygen and parenteral fluids, is essential for infants < 1 year who are at greatest risk of complications and permanent sequelae. Steroids and beta2-agonists are also used in the management of severe neonatal pertussis. Several antibiotics have been shown to reduce the level of bacterial colonisation of the respiratory tract, however, erythromycin is accepted to be the treatment of choice. Erythromycin reduces severity and duration of disease, even if started during the paroxysmal phase. A 14 day course is recommended although side effects may limit compliance; a recent study indicates that a 7 day course may have similar efficacy in terms of eradication and prevention of relapse. Alternatives to erythromycin are clarithromycin, azithromycin and trimethoprim-sulfamethoxazole. Fluoroquinolones have good in vitro activity against both B. pertussis and B. parapertussis and may be useful in the treatment of adult patients with pertussis, although there are no supporting clinical data at present. Erythromycin prophylaxis is also recommended for close household contacts of patients with pertussis.

Animals↗
PubMed2000

Bordetella pertussis infection: pathogenesis, diagnosis, management, and the role of protective immunity.

Whooping cough is presently one of the ten most common causes of death from infectious disease worldwide. Despite a high vaccine uptake, resurgences of this disease have been observed in several countries. Virulence factors of Bordetella pertussis include agglutinogens, fimbriae, P.69/pertactin, pertussis toxin, filamentous haemagglutinin, adenylate cyclase, tracheal cytotoxin, dermonecrotic toxin, lipopolysaccharide, tracheal colonisation factor, serum resistance factor, and type III secretion. Virulence factor expression is regulated by the bvgAS locus, a two-component signal transduction system. The pathophysiologic sequence consists of attachment (fimbriae, P.69/pertactin, tracheal colonisation factor, pertussis toxin, filamentous haemagglutinin), evasion of host defence (adenylate cyclase, pertussis toxin, serum resistance factor), local effects (tracheal cytotoxin), and systemic effects (pertussis toxin). Bordetella pertussis is transmitted by respiratory droplets and causes disease only in humans. Various diagnostic methods are available, including culture, serological methods, and the polymerase chain reaction. Serotyping of isolates to detect agglutinogens 2 and 3 is useful because serotype 1,2 may be associated with higher mortality, and antibodies to these antigens (agglutinins) may be protective in both animals and humans. Immunisation using whole-cell vaccine is effective but is reactogenic. Acellular vaccines containing one to five components are being used increasingly in various countries. Protective immunity to pertussis correlates with high levels of antibody to each of pertactin, fimbriae, and pertussis toxin; however, doubt remains as to the relationship between agglutinogen 3 and fimbria 3, making results of trials investigating these virulence factors difficult to interpret.

Animals↗
PubMed2000

Antibodies to parvovirus B19 non-structural protein are associated with chronic but not acute arthritis following B19 infection.

OBJECTIVE: To determine the incidence and significance of antibodies to the parvovirus B19 non-structural (NS1) protein in B19-infected persons during acute infection and convalescence. METHODS: The B19 NS1 protein was expressed in SF9 cells using the baculovirus expression system and was used to prepare immunofluorescence slides. These were used in a fluorescent antibody test to determine anti-B19 NS1 IgG in a well-characterized cohort of 53 persons at the time of acute B19 infection and again after a follow-up period of 26-85 months. Results were examined for statistical significance by the use of Fisher's exact test. RESULTS: NS1 antibodies were detected in five of 32 persons with acute B19 infection (four with arthritis) and 10 of 53 persons with past B19 infection (six with chronic arthritis and two with chronic arthritis and chronic fatigue syndrome). Regarding the correlation of NS1 antibodies and arthritis, at the time of acute infection four of 24 persons with arthritis had NS1 antibodies detected compared with one of eight persons with any other symptoms (P: = 1). During convalescence, eight of 20 persons with chronic arthritis had NS1 antibodies compared with two of 33 with symptoms of any other category (all except one were asymptomatic) (P: = 0.007). All 10 patients with NS1 antibodies during convalescence had arthritis during acute infection, which persisted in eight persons until the time of follow-up. CONCLUSION: Antibodies to parvovirus B19 NS1 protein are associated with chronic but not with acute arthritis after B19 infection.

Acute Disease↗
PubMed2000

An association between sudden infant death syndrome (SIDS) and Helicobacter pylori infection.

BACKGROUND: Helicobacter pylori has recently been detected in the stomach and trachea of cases of sudden infant death syndrome (SIDS) and proposed as a cause of SIDS. AIMS: To establish the incidence of H pylori in the stomach, trachea, and lung of cases of SIDS and controls. METHODS: Stomach, trachea, and lung tissues from 32 cases of SIDS and eight control cases were examined retrospectively. Diagnosis of SIDS was based on established criteria. Controls were defined by death within 1 year of age and an identifiable cause of death. Tissues were examined histologically for the presence of bacteria. Extracted DNA from these tissues was tested for H pylori ureC and cagA sequences by nested polymerase chain reaction and amplicons detected by enzyme linked immunosorbent assay (ELISA). The cut off for each ELISA for each of the tissue types was taken as the mean optical density plus two times the standard deviation of a range of negative controls. RESULTS: Ages of SIDS cases ranged from 2 to 28 weeks. Ages of controls ranged from 3 to 44 weeks. For the ureC gene, 25 SIDS cases were positive in one or more tissues compared with one of the controls. For the cagA gene, 25 SIDS cases were positive in one or more tissues compared with one of the controls. CONCLUSIONS: There is a highly significant association between H pylori ureC and cagA genes in the stomach, trachea, and lung of cases of SIDS when compared with controls.

DNA, Bacterial↗
PubMed1999

The Bpel locus encodes type III secretion machinery in Bordetella pertussis.

Type III secretory genes(Bscl, J, K, L, N and O) have recently been identified in Bordetella bronchiseptica and shown to be under the control of the BvgAS locus. We examined a 35 616 byte DNA sequence amplified from Bordetella pertussis Tohama I for homology with known type III secretory genes in Yersinia spp. and Pseudomonas sppand a total of 20 homologous open reading frames were detected. Putative type III secretion proteins in B. pertussis were designated according to their homology with type III secretion proteins in B. bronchiseptica, Yersinia and Pseudomonas. These ORFs were arranged in two putative operons, which together we have designated as the BpeI locus. The first spans nucleotides 23385-7888 and encodes the putative proteins LcrH1, BopD, BopB, LcfH2, BscI, BscJ, BscK, BscL, BscN, BscO, BscQ, BscR, BscS, BscT, BscU, and BscC, in this order. The second spans nucleotides 23580-29863 and encodes the putative proteins LcrE, LcrD, BscD and BscF, in this order. The homology of these proteins to type III secretory proteins was B. bronchiseptica (73-99%), Yersinia spp. (17-65%), Pseudomonas spp. (18-64%). The B. pertussis proteins were similar to their homologues in B. bronchiseptica, Yersinia and Pseudomonas in terms of length, molecular weight and isoelectric point. Coiled-coil domains were detected in putative translocation proteins, BopB and BopD. BopB and BopD were similar to each other, to the RTX toxin family and to cyaA, cyaB, cyaD and cyaE. The percentage G+C content of the sequence analysed was 66.16%, which is similar to the published percentage G+C (67-70%) for the B. pertussis chromosome.

Amino Acid Sequence↗
PubMed1999

Implications of endotracheal tube biofilm for ventilator-associated pneumonia.

OBJECTIVE: To determine the relationship between, and antibiotic resistance of, endotracheal tube (ET) biofilm and pulmonary pathogens in ventilator-associated pneumonia (VAP). SETTING: General intensive care units in two university teaching hospitals. DESIGN: The microbiology of ET biofilm and tracheal samples from patients with and without VAP were compared. For individual patients, matching pairs of pathogens were confirmed as identical and characterised for antibiotic susceptibility. PATIENTS: 40 intensive care unit patients - 20 with VAP, 20 without VAP as control. The duration of intubation (median and range) was 6.5 days (3-17) and 5 days (2-10), respectively. MEASUREMENTS AND RESULTS: Samples of tracheal secretions were taken during ventilation for bacteriological culture. Following extubation, ETs were examined for the presence of biofilm. Isolates of high pathogenic potential included Staphylococcus aureus, enterococci, Enterobacteriaceae, pseudomonads and Candida spp. Where the same microorganism was found on tracheal and ET samples by phenotyping, these were confirmed as identical by genotyping and characterised for antibiotic susceptibility in both the free floating and biofilm forms. Seventy per cent of patients with VAP had identical pathogens isolated from both ET biofilm and tracheal secretions. No pairing of pathogens was observed in control patients (p < 0.005). Susceptibility data for these pairs show that the ET acts as a reservoir for infecting microorganisms which exhibit significantly greater antibiotic resistance than their tracheal counterparts. CONCLUSION: This investigation provides further evidence for the role of ET biofilm in VAP. The difficulty in eradicating an established microbial biofilm using antibiotics implies that increased attention must be directed towards modification of the ET to prevent or substantially reduce biofilm formation.

Adolescent↗
PubMed1999

Semiquantitative polymerase chain reaction enzyme immunoassay for the diagnosis of pertussis.

The two most commonly used targets for diagnosis of pertussis by the polymerase chain reaction have been the pertussis toxin promoter and the repeated insertion sequence IS481. A comparative assessment of these primers was performed on routinely collected nasopharyngeal swabs, stored at -20 C, using novel semiquantitative enzyme immunoassays. Both sets of primers behaved similarly with bacterial suspensions, and the 17 culture-positive nasopharyngeal swabs were also positive with the pertussis toxin promoter primers, with one exception, which had been subject to prolonged storage. Significantly more of the 69 culture-negative swabs were positive with the pertussis toxin promoter primers (n = 36) than with the IS481 primers (n = 18). To determine the effect of inhibitors, a comparative assessment of three primer pairs against human DNA (beta-globin and glyceraldehyde-3-phosphate dehydrogenase) was also performed.

Child↗
PubMed1999

Pseudomonas aeruginosa pyocyanin and 1-hydroxyphenazine inhibit fungal growth.

AIM: To examine strains of Pseudomonas aeruginosa for specific antifungal factors. METHODS: Two clinical strains of P aeruginosa with strong in vitro inhibition (by cross streak assay) of Candida albicans and Aspergillus fumigatus were examined. Both strains were isolated from sputum--one from a patient with cystic fibrosis and one from a patient with bronchiectasis. Bacterial extracts were fractionated by high performance liquid chromatography and examined by ultraviolet absorbance and mass spectroscopy. Antifungal activity against C albicans and A fumigatus was determined in a well plate assay. RESULTS: Pyocyanin was the major antifungal agent of P aeruginosa; 1-hydroxy-phenazine also possessed activity. Pyocyanin MICs for C albicans and A fumigatus were > 64 micrograms/ml. These phenazines were active against nine other yeast species pathogenic for man. Preliminary experiments also suggested possible inhibition of yeast mycelial transformation in C albicans by pyocyanin. CONCLUSIONS: There may be a role for pyocyanin and 1-hydroxyphenazine in the prevention of pulmonary candidiasis in patients colonised by P aeruginosa.

Aspergillus fumigatus↗
PubMed1999

Cell adhesion molecules in the pathogenesis of and host defence against microbial infection.

Eukaryotic cell adhesion molecules (CAMs) are used by various cells and extracellular molecules in host defence against infection. They are involved in many processes including recognition by circulating phagocytes of a site of inflammation, transmigration through the endothelial barrier, diapedesis through basement membrane and extracellular matrix, and release of effector mechanisms at the infected site. CAMs involved in leucocyte-endothelial cell interaction include the selectins, integrins, and members of the immunoglobulin superfamily. However, CAMs are also used by various microorganisms (protozoa, fungi, bacteria, and viruses) during their pathogenesis. For example, bacteria that utilise CAMs include Mycobacterium tuberculosis, Listeria monocytogenes, Yersinia spp, enteropathogenic Escherichia coli, Shigella spp, Neisseria spp, Bordetella spp, and Borrelia burgdorferi. In addition, CAMs are involved in the pathogenetic effects of the RTX toxins of Pasteurella haemolytica, Actinobacillus actinomycetemcomitans, and the superantigen exotoxins of Staphylococcus aureus and Streptococcus pyogenes. A recurrent and topical theme of potential importance within the bacterial group is the intimate relation between CAMs, bacterial protein receptors, and type III secretion systems. For example, the IpaBCD protein complex is secreted by the type III system of Shigella flexneri and interacts with alpha 5 beta 1 integrin on the eukaryotic cell surface, followed by Rho mediated internalisation; this illustrates the relevance of cellular microbiology. CAMs might prove to be novel therapeutic targets. Comparative genomics has provided the knowledge of shared virulence determinants among diverse bacterial genera, and will continue to deepen our understanding of microbial pathogenesis, particularly in the context of the interaction of prokaryotic and eukaryotic molecules.

Cell Adhesion Molecules↗
PubMed1999

Parvovirus B19 is associated with benign testes as well as testicular germ cell tumours.

AIMS: Parvovirus B19 has been demonstrated in testes of patients with germ cell tumours but not in controls, raising the possibility that the virus has an aetiological role in these tumours. The aims of this study were to investigate the association of the virus with germ cell tumours and to localise the virus histologically. METHODS: DNA was extracted from paraffin wax embedded sections of testes from 10 seminomas, eight teratomas, two mixed seminoma/teratomas, and 10 testes showing benign histology. Polymerase chain reaction (PCR) amplification of three regions within the NS and VP1/2 genes was carried out in duplicate on all samples. One PCR positive case (seminoma/teratoma) was examined by microdissection of histologically defined tissue components followed by PCR amplification of parvoviral sequences. Samples from PCR positive patients were immunostained using a B19 specific monoclonal antibody. RESULTS: Seven cases were PCR positive, these comprised two of 10 seminomas, one of two mixed tumours, none of eight teratomas, and four of 10 benign controls. PCR analysis of the material microdissected from the seminoma/teratoma showed the presence of the virus in regions of seminoma, teratoma, intratubular germ cell neoplasia, normal tubules, and connective tissue. All patient samples studied immunohistochemically were negative. CONCLUSIONS: This confirms the presence of parvovirus B19 in a proportion of germ cell tumours; however, in one patient, the virus was widespread in the tissue components and not confined to tumour cells. In addition, the virus was present in control benign testes. These data suggest that B19 might not be of aetiological importance in germ cell tumours of testis.

Adult↗
PubMed1997

Parvovirus B19 infection in AIDS patients.

Bone marrow of 61 HIV-1-infected patients and 23 control patients was examined to determine the incidence of B19 infection and its clinical impact in HIV-1-infected persons. Of the 61 HIV-infected patients studied, ages ranged from 22-47 years with a mean of 33.2 years. There was a man:woman ratio of 3.8:1. With regard to staging of HIV disease at the time of bone marrow sampling, 52 patients were CDC group 4, 5 patients were CDC group 3, and 4 patients were CDC group 2. Control patients, were not known to be HIV-1-infected, and had one of the following conditions: lymphoma, leukaemia, thrombocytopenia, thrombocytosis, anaemia, multiple myeloma, raised serum IgM. Thirteen of 61 HIV-infected patients and 0 of 23 control patients were positive for B19 DNA in bone marrow (two-tailed P value = 0.016). Within the HIV-infected group, the average haemoglobin among persons testing B19 DNA positive (n = 13) was 11.1 g/dl, compared with 11.5 g/dl among persons testing B19 DNA negative (n = 48). In conclusion, B19 persistence may be common and frequently subclinical in AIDS patients.

Adult↗