Therapeutic beds: the Trojan horses of the 1990s?
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Beds↗
Biomedical subjects
P R Sisson
Publications and source records attributed to P R Sisson.
Nosocomial infection due to enterococci attributed to a fluidized microsphere bed. The value of pyrolysis mass spectrometry.
The potential of fluidised microsphere beds as sources of nosocomial Enterococcal infection was investigated with the help of pyrolysis mass spectrometry. Isolates from clinical specimens collected from two patients who were nursed sequentially on a fluidized microsphere bed were compared with similar isolates cultured from the microspheres before and after decontamination. Pyrolysis mass spectrometry confirmed that nosocomial spread had indeed occurred and that the existing decontamination process was inadequate. Recommendations for improvements to this decontamination process appear to have prevented further cases.
Adult↗
Rapid identification of species within the Mycobacterium tuberculosis complex by artificial neural network analysis of pyrolysis mass spectra.
An artificial neural network (ANN) was trained to distinguish between Mycobacterium tuberculosis and M. bovis with averaged pyrolysis mass spectra from duplicate subcultures of four strains of each of these species, each pyrolysed in triplicate. Once trained, the ANN was interrogated with spectrum data from the original organisms (the "training set") and from 26 other mycobacterial isolates (the "challenge set") of the M. tuberculosis complex (MTBC). Eight strains of M. bovis and 13 of M. tuberculosis, whether sensitive or variously resistant to antituberculosis drugs, were identified in agreement with conventional identification. Four strains of "M. africanum" were identified as M. bovis. Of two atypical M. tuberculosis strains from South India, one was identified as M. tuberculosis and the other as M. bovis. Six strains of BCG proved heterogeneous; two gave equivocal identifications, three were identified as M. bovis and one was identified as M. tuberculosis.
Humans↗
Application of pyrolysis mass spectroscopy and SDS-PAGE in the study of the epidemiology of Pseudomonas cepacia in cystic fibrosis.
Representative isolates of Pseudomonas cepacia from 15 cystic fibrosis (CF) patients attending the Respiratory Unit of Alder Hey Childrens' Hospital were investigated by SDS-PAGE of whole-cell polypeptides and by pyrolysis mass spectroscopy (PMS). SDS-PAGE was less discriminatory than PMS. Eleven isolates were indistinguishable by PMS and considered to represent re-isolates of an endemic strain; four isolates were distinct from this group, and from one another. P. cepacia was first isolated on the unit in July 1989 from a patient who had attended a UK selection meeting for a Canadian CF camp. A ward and outpatient segregation policy was introduced, but colonisation of further patients occurred. In August 1991, the Adult CF Association recommended that all social activities involving colonised patients should cease. This, and an increased awareness amongst older CF patients of the risks of person-to-person transmission, was associated with a marked decline in new cases. Social activity and hospital admissions were compared for colonised patients during the year before colonisation with P. cepacia, and matched patients who did not acquire the endemic strain. This showed a significantly higher attendance at CF social events for colonised patients, but no significant association between colonisation and hospital admission. These results are strong indirect evidence that transmission of P. cepacia occurs through social contact outside the hospital environment.
Adolescent↗
Rapid characterisation of Candida albicans by pyrolysis mass spectrometry.
Clinical isolates (41) of Candida spp. from three possible outbreaks of nosocomially-acquired infection were compared by pyrolysis mass spectrometry (PMS) and by a combined morphotyping and resistotyping (M-R typing) method. Both systems characterised all the isolates and distinguished one isolate of C. tropicalis and another of C. glabrata from the 39 isolates of C. albicans. Results from both systems suggested that cross-infection with a single strain contributed to two of the outbreaks. In several instances, more than one strain of C. albicans was found amongst multiple isolates from the same patient. PMS is a simple, rapid and objective technique capable of characterising C. albicans isolates; discrimination was similar to M-R typing.
Candida albicans↗
Mycobacterium avium-intracellulare from patients with and without AIDS compared by pyrolysis mass spectrometry.
Isolates of Mycobacterium avium-intracellulare complex (MAI) from AIDS and non-AIDS patients were compared by pyrolysis mass spectrometry (PyMS). Those from AIDS patients were more closely related to each other than those from non-AIDS patients which were significantly more disparate.
Acquired Immunodeficiency Syndrome↗
Pyrolysis mass spectrometry of Listeria monocytogenes isolates from sheep.
Forty-eight isolates of Listeria monocytogenes from sheep and silage, involved in five small outbreaks of listeriosis, were compared by pyrolysis mass spectrometry (PyMS). The method clustered isolates from single animals, and showed that epidemiologically associated isolates were closely related to each other. PyMS is a simple technique capable of analysing large numbers of samples daily, and its application in veterinary studies should help to elucidate the epidemiology of listeriosis.
Animals↗
Application of pyrolysis mass spectrometry to the investigation of outbreaks of food poisoning and non-gastrointestinal infection associated with Bacillus species and Clostridium perfringens.
Eighteen isolates of Bacillus species and 15 of Clostridium perfringens, all of which had been associated with outbreaks of either food poisoning or non-gastrointestinal infection (NGI), were examined for relatedness by pyrolysis mass spectrometry (PyMS). The PyMS-analysis correctly clustered all the groups of epidemiologically related isolates of both genera, and distinguished all the single, epidemiologically unrelated isolates of the same species. PyMS is a simple, rapid and inexpensive technique which can provide useful and accurate inter-strain comparisons within both the Bacillus and Clostridium genera in complete accord with conventional serological typing results.
Bacillaceae Infections↗
Nosocomial infection with Clostridium difficile investigated by pyrolysis mass spectrometry.
Fifty-eight isolates of Clostridium difficile from two distinct outbreaks were examined for inter-strain similarity by pyrolysis mass spectrometry (PMS). The first outbreak began on a geriatric acute unit and spread to a long stay geriatric facility. PMS analysis showed that most isolates from both sites were indistinguishable. Isolates obtained in the preceding year from the long stay facility were found to be closely similar to these outbreak isolates. In the second, smaller outbreak on a female medical ward in another general hospital, PMS again showed that a single strain was probably responsible. Representative isolates from these two different outbreaks were shown to be distinct. The ability to compare rapidly large numbers of isolates of C. difficile makes PMS attractive for initial screening in suspected outbreaks, providing important information for outbreak management and allowing conventional typing methods to be concentrated on relevant isolates.
Aged↗
Rapid differentiation of Mycobacterium xenopi from mycobacteria of the Mycobacterium avium-intracellulare complex by pyrolysis mass spectrometry.
Thirty four cultures of slow growing, Tween-80 negative mycobacteria were analysed by pyrolysis mass spectrometry. The results showed that pyrolysis mass spectrometry could positively distinguish strains of Mycobacterium xenopi from those of the Mycobacterium avium-intracellulare (MAI) complex. Pyrolysis mass spectrometry may be a useful technique for the rapid characterisation of non-tuberculous mycobacteria in such clinical settings as their isolation from immunocompromised patients-for example, those with AIDS.
Hot Temperature↗
Differentiation between mycobacteria of the Mycobacterium tuberculosis complex by pyrolysis mass spectrometry.
32 isolates belonging to the Mycobacterium tuberculosis complex were examined by pyrolysis mass spectrometry (PyMS). This technique demonstrated that recent clinical isolates of M. africanum were indistinguishable from those of M. bovis and together formed a homogeneous group distinct from M. tuberculosis. Isolates of BCG were heterogeneous and more closely related to laboratory-adapted strains of M. tuberculosis than to recent isolates of either M. tuberculosis or M. bovis. PyMS is a simple and inexpensive technique which gives interesting information on the relationships between members of the M. tuberculosis complex and can make the clinically important distinction between strains of M. bovis and M. tuberculosis accurately and much more rapidly than conventional techniques.
Mass Spectrometry↗
Strain differentiation of nosocomial isolates of Pseudomonas aeruginosa by pyrolysis mass spectrometry.
Pyrolysis mass spectrometry (PyMS) was used for rapid interstrain comparison of Pseudomonas aeruginosa isolates from a small outbreak of sternal wound infections in a cardiothoracic surgical ward. The PyMS results were compared with those obtained by conventional O-serotyping. All the isolates were phage non-typable. Evidence obtained from PyMS of identity/non-identity between isolates correlated completely with that obtained by O-typing and correctly identified those isolates comprising the epidemic strain, in one instance in advance of O-serotyping. The speed and versatility of PyMS make it an attractive technique for the initial screening of isolates from nosocomial outbreaks of infection with P. aeruginosa and other organisms.
Bacterial Typing Techniques↗
Inter-strain comparison by pyrolysis mass spectrometry in the investigation of Staphylococcus aureus nosocomial infection.
Pyrolysis mass spectrometry (PyMS) was used to examine isolates of Staphylococcus aureus from an outbreak of wound infections on a cardiothoracic surgical unit, some of which were thought to have been related to a point-source in the operating theatre. The PyMS results were compared with the results of phage typing. Both methods suggested that a single strain of S. aureus, of phage pattern 29/52/52A/79/80/81, was responsible for some of the wound infections, but PyMS also identified two patients with phage non-typable isolates. Phage typing indicated four staff members as possible carriers of the epidemic strain, but PyMS indicated only two. Epidemiological enquiry confirmed that one of the two members of staff identified by both methods was likely to have been the source of the theatre-based infection. PyMS is a rapid and relatively inexpensive technique for the investigation of nosocomial S. aureus infection and was more discriminatory than phage typing in this instance.
Carrier State↗
Rapid inter-strain comparison by pyrolysis mass spectrometry in nosocomial infection with Xanthomonas maltophilia.
Seventeen strains of Xanthomonas maltophilia and one strain of Pseudomonas cepacia were examined by pyrolysis mass spectrometry (PYMS). The Xanthomonas strains comprised 11 clinical and environmental isolates from a suspected outbreak of colonization and infection on a heart-lung transplant intensive care unit, two strains from patients elsewhere in the same hospital and four strains from a national reference collection. The single isolate of Pseudomonas cepacia was from a sink in the same affected intensive care unit. A series of discriminant analyses performed on the PYMS-derived data showed that, whereas six strains of Xanthomonas from the respiratory tract, blood and ventilatory equipment of one of the affected patients were indistinguishable, all the other isolates were distinct. The results of PYMS rapid inter-strain comparison were in accord with those of an epidemiological investigation which suggested that the episode was due to unauthorized reuse of disposable nebulizers and not to cross-infection between patients. Pyrolysis mass spectrometry with rapid data analysis is a potentially useful technique for the investigation of nosocomial infections due to organisms such as X. maltophilia.
Bacteriological Techniques↗
Rapid inter-strain comparison by pyrolysis mass spectrometry of coagulase-negative staphylococci from persistent CAPD peritonitis.
Pyrolysis mass spectrometry (PyMS) was used as a method of rapid inter-strain comparison of 19 isolates of coagulase-negative staphylococci from episodes of CAPD peritonitis. Thirteen isolates were from multiple, but distinct, episodes of peritonitis in 6 patients and the remaining 6 isolates were from 6 patients with single episodes. The results, expressed in terms of identity/non-identity of strains, were compared with those obtained using an established typing system comprising an extended antibiogram, determination of biotype and plasmid profile analysis. The PyMS results for inter-strain comparison were in agreement with the reference typing scheme results. PyMS can be used in this setting to rapidly obtain evidence that persistent infection is/is not likely to be due to the same organism, although it cannot be used for formal typing. The results by both methods showed that serial, apparently distinct, episodes of peritonitis over periods as long as 120 days may be due to the same strain of coagulase-negative staphylococcus. Clinically based distinctions between recurrence of infection (same strain) and re-infection (different strains) may not always be supported by the microbiological evidence.
Coagulase↗
Incrimination of an environmental source of a case of Legionnaires' disease by pyrolysis mass spectrometry.
Following a case of Legionnaires' disease Legionella pneumophila of the same serogroup was isolated from the hot water system of the hotel which had been epidemiologically implicated as the source of the infection. Pyrolysis mass spectrometry (PyMS) was used to compare 11 isolates from the hotel water sample with the patient's strain. Epidemiologically unrelated isolates, both clinical and environmental, of the same serogroup and monoclonal antibody type of L. pneumophila were included in the same analysis, together with relevant reference strains. The patient strain was shown to be indistinguishable from seven of the hotel water isolates, but clearly different from other unrelated clinical isolates, the reference strains and some of the other environmental isolates. PyMS is a rapid and cheap method for inter-strain comparison for L. pneumophila.
Aged↗
Jackdaws and magpies as vectors of milkborne human Campylobacter infection.
In 1990 we reported that milk bottles pecked by jackdaws and magpies were a probable source of human campylobacter infection. During April to June 1990 an extended study of campylobacter infections was carried out in the Gateshead area. Prior to the study a health education programme was undertaken in an attempt to reduce human infection. Fifty-nine cases of human infection were recorded and 52 were interviewed. Thirty were entered into a case control study which demonstrated a very strong association between consumption of pecked milk and human campylobacter infection (chi 2 = 12.6, P less than 0.0004). It was estimated that between 500 and 1000 jackdaws (Corvus monedula) were present in the area where milk bottles were pecked and 63 isolates of campylobacter were made from the bill and cloaca. Target bottles were put out in the early mornings and campylobacters were isolated from 12 of 123 pecked bottles. Typing of the campylobacters revealed a wide distribution of strains amongst birds, pecked milk and human infections. The health education programme had only limited success.
Adolescent↗
Microbiology, chemotherapy and mortality of brain abscess in Newcastle-upon-Tyne between 1979 and 1988.
71 patients admitted to Newcastle Regional Neurosurgical Centre between 1979 and 1988 with a diagnosis of brain abscess are reviewed. The overall mortality was 9.9%, with an operative mortality of 7%. The bacteriology of these abscesses is discussed in detail, together with the importance of effective standardized antimicrobial treatment regimens. The low mortality figures appeared to be in direct relationship to early recognition of this condition, prompt surgical intervention and effective chemotherapy.
Ampicillin↗