F.K. Gould

Outcomes of lung transplantation for cystic fibrosis in a large UK cohort

Background: Lung transplantation is an important option to treat patients with advanced cystic fibrosis (CF) lung disease. The outcomes of a large UK cohort of CF lung transplantation recipients is reported. Methods: Retrospective review of case notes and transplantation databases. Results: 176 patients with CF underwent lung transplantation at our centre. The majority (168) had bilateral sequential lung transplantation. Median age at transplantation was 26 years. Diabetes was common pretransplantation (40%). Polymicrobial infection was common in individual recipients. A diverse range of pathogens were encountered, including the Burkholderia cepacia complex (BCC). The bronchial anastomotic complication rate was 2%. Pulmonary function (forced expiratory volume in 1 s % predicted) improved from a pretransplantation median of 0.8 l (21% predicted) to 2.95 l (78% predicted) at 1 year following transplantation. We noted an acute rejection rate of 41% within the first month. Our survival values were 82% survival at 1 year, 70% at 3 years, 62% at 5 years and 51% at 10 years. Patients with BCC infection had poorer outcomes and represented the majority of those who had a septic death. Data are presented on those free from these infections. Bronchiolitis obliterans syndrome (BOS) and sepsis were common causes of death. Freedom from BOS was 74% at 5 years and 38% at 10 years. Biochemical evidence of renal dysfunction was common although renal replacement was infrequently required (<5%). Conclusion: Lung transplantation is an important therapeutic option in patients with CF even in those with more complex microbiology. Good functional outcomes are noted although transplantation associated morbidities accrue with time.

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.

Fluorogenic substrates for the detection of microbial nitroreductases

Aims: To synthesize and evaluate fluorogenic substrates for the detection of microbial nitroreductases. These substrates, all based on 7‐nitrocoumarin, may be reduced to form fluorescent aminocoumarins.

Evaluation of novel fluorogenic substrates for the detection of glycosidases in Escherichia coli and enterococci

Aims:  Enzyme substrates based on 4‐methylumbelliferone are widely used for the detection of Escherichia coli and enterococci in water, by detection of β‐glucuronidase and β‐glucosidase activity respectively. This study aimed to synthesize and evaluate novel umbelliferone‐based substrates with improved sensitivity for these two enzymes.

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.

Prosthetic joint infections: single versus combination therapy

Prosthetic joint replacement is increasingly used to alleviate pain and increase mobility. Bone and joint infections remain a therapeutic dilemma for healthcare providers in all fields. Antimicrobial agents combined with appropriate surgical techniques play a vital role in eradicating infections associated with prosthetic joints. The question still remains whether monotherapy or combination therapy is effective in this situation because there is a paucity of well-defined comparative studies. We reviewed in vitro and in vivo studies evaluating the effectiveness of various antimicrobial agents either as single agents or in combination.

Note : Cyclohexenoesculetin‐β‐D‐glucoside: a new substrate for the detection of bacterial β‐D‐glucosidase

A new substrate for the detection of bacterial β‐D‐glucosidase was evaluated as an alternative to aesculin. This substrate, 3,4‐cyclohexenoesculetin‐7‐β‐D‐glucoside, was compared with aesculin for the detection of β‐D‐glucosidase in 150 enterococci, 40 streptococci, 12 Listeria sp. and 250 strains of Enterobacteriaceae. In the Gram‐positive strains tested, aesculin hydrolysis correlated with hydrolysis of 3,4‐cyclohexenoesculetin‐7‐β‐D‐glucoside. In the Gram‐negative strains the new substrate was hydrolysed by all aesculin‐positive strains and also by four strains (10%) of Escherichia coli which gave a negative aesculin reaction. 3,4‐Cyclohexenoesculetin‐7‐β‐D‐glucoside was shown to be a reliable alternative to aesculin and was shown to have significant advantages over aesculin when incorporated into solid media. This was due to the non‐diffusible end product produced by hydrolysis of 3,4‐cyclohexenoesculetin‐7‐β‐D‐glucoside in the presence of iron.

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.

Evaluation of a new chromogenic agar medium for isolation and identification of Group B streptococci

Aims:  To evaluate a new chromogenic agar as a screening medium for the isolation of Group B streptococci from high vaginal swabs from pregnant women.

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.