Identification of infectious Pseudomonas aeruginosa strains in an occupational saturation diving environment

OBJECTIVES

Occupational saturation divers have various skin disorders, of which skin infections are the most serious and frequent. Pseudomonas aeruginosa is the microbe most often isolated from skin infections in divers. The purpose of the present work was (a) to report the occurrence of P aeruginosa in skin infections in operational saturation diving in the North Sea from 1987 to 1995; (b) to report the environmental occurrence of P aeruginosa in saturation diving systems, and finally (c) to identify possible relations between infection related to strains of P aeruginosa and environmental isolates of the microbe.

RESULTS

During the period 1987-95, P aeruginosa was isolated from 257 skin infections in operational saturation divers. Most of the isolates related to infection by P aeruginosa show a unique growth inhibition pattern towards the normal skin flora, and the serotype pattern of P aeruginosa from skin infections is limited compared with similar infections in non-divers. In a mini-epidemiological study on board one diving vessel during one operational diving period, five significantly different DNA fragment profiles were found among the 12 isolates related to infection by P aeruginosa obtained from the saturation system. In two cases the infectious genotypes were detected in the fresh water for the saturation chambers weeks before the arrival of the infected diver.

CONCLUSIONS

The most commonly used epidemiological marker for P aeruginosa world wide, also used in earlier studies, is serotyping, but with pulsed field gel electrophoresis (PFGE) miniepidemiology it was shown to be insufficient for epidemiological purposes in saturation environments. PFGE analyses were shown to be superior both to antibacterial factor and to serotyping in epidemiological analyses of P aeruginosa infections in saturation diving.

Diver's hand: a skin disorder common in occupational saturation diving

Saturation divers regularly inspect North Sea installations, working at depth for periods of 12-16 days. Diver's hand is a particular problem in saturation diving, and there is no effective protection or treatment available. This paper presents the occurrence of diver's hand and describes the disease in clinical and epidemiological terms. Three studies of diver's hand have been carried out, in 1990, 1994, and 1995. Most long term saturation divers have had diver's hand at some time in their professional career. Diver's hand seems able to occur without any previous skin symptoms, and divers without diver's hand can have several other skin symptoms during a saturation period. It is likely that diver's hand is a specific phenomenon associated with saturation diving.

Survival of infectious Pseudomonas aeruginosa genotypes in occupational saturation diving environment and the significance of these genotypes for recurrent skin infections

BACKGROUND

Occupational saturation divers suffer from various skin disorders, of which skin infections are the most serious and frequent. Pseudomonas aeruginosa is the microbe most often isolated.

METHODS

P. aeruginosa isolates from 292 skin infections in operational saturation divers and about 800 isolates from occupational saturation diving systems have been collected during the period 1986 to 1998. Genotyping of the isolates has been performed by using restriction enzyme fragmentation and pulsed field gel electrophoresis.

RESULTS

Four hundred and seventy-two P. aeruginosa isolates have been analyzed, of which 181 originate from skin infections in divers. Ninety-seven significantly different P. aeruginosa genotypes have been defined. Some of these genotypes are solely found from skin infections, some solely from the saturation environment and about 25% were found both from infections and from the saturation environment. Eight frequent infectious genotypes have been identified, and these are shown to be present over several years, both in infections and in the saturation environment.

CONCLUSIONS

The study suggests that skin infections in occupational saturation divers are commonly caused by environmental strains.

The impact of environmental Pseudomonas aeruginosa genotypes on skin infections in occupational saturation diving systems

Skin infection caused by Pseudomonas aeruginosa is the most frequent health problem associated with occupational saturation diving on the Norwegian continental shelf. In the course of 14-y surveillance of infection and environmental control in occupational offshore saturation diving systems, a collection of approximately 1000 P. aeruginosa isolates has been amassed. Retrospective genomic analyses using restriction enzyme fragmentation and pulsed-field gel electrophoresis have identified 24 of 76 environmental P. aeruginosa genotypes as being of significance for single infections, outbreaks of infections and recurrent skin infections in occupational diving systems. In addition, these genomic analyses have made it possible to separate outbreaks of infection into outbreaks with 1 single genotype and clusters of infections where different genotypes are involved. We conclude that the established, assumed diver-to-diver contagion vector ought to be replaced by a environmental contagion vector as the most likely vector within these specific occupational environments. Furthermore, consecutive presence of the frequent environmental/infectious genotypes demands specific improvement of infection prevention and control in these systems.

Development and evaluation of a new PCR assay for detection of Pseudomonas aeruginosa D genotype

This report describes a new PCR-based assay for the detection of Pseudomonas aeruginosa genotype D in occupational saturation diving systems in the North Sea. This genotype has persisted in these systems for 11 years (1993-2003) and represents 18% of isolates from infections analysed during this period. The new PCR assay was based on sequences obtained after randomly amplified polymorphic DNA (RAPD)-PCR analysis of a group of isolates related to diving that had been identified previously by pulsed-field gel electrophoresis (PFGE). The primer set for the D genotype targets a gene that codes for a hypothetical class 4 protein in the P. aeruginosa PAO1 genome. A primer set able to detect P. aeruginosa at the species level was also designed, based on the 23S-5S rDNA spacer region. The two assays produced 382-bp and 192-bp amplicons, respectively. The PCR assay was evaluated by analysing 100 P. aeruginosa isolates related to diving, representing 28 PFGE genotypes, and 38 clinical and community P. aeruginosa isolates and strains from other species. The assay identified all of the genotype D isolates tested. Two additional diving-relevant genotypes (TP2 and TP27) were also identified, as well as three isolates of non-diving origin. It was concluded that the new PCR assay is a useful tool for early detection and prevention of infections with the D genotype.

Concentration of circulating autoantibodies against HSP 60 is lowered through diving when compared to non-diving rats

OBJECTIVE

Skin and ear infections, primarily caused by Pseudomonas aeruginosa (P. aeruginosa), are recurrent problems for saturation divers, whereas infections caused by P. aeruginosa are seldom observed in healthy people outside saturation chambers. Cystic fibrosis (CF) patients suffer from pulmonary infections by P. aeruginosa, and it has been demonstrated that CF patients have high levels of autoantibodies against Heat shock protein 60 (HSP60) compared to controls, probably due to cross-reacting antibodies induced by P. aeruginosa. The present study investigated whether rats immunised with P. aeruginosa produced autoantibodies against their own HSP60 and whether diving influenced the level of circulating anti-HSP60 antibodies.

METHODS

A total of 24 rats were randomly assigned to one of three groups ('immunised', 'dived' and 'immunised and dived'). The rats in group 1 and 3 were immunised with the bacteria P. aeruginosa, every other week. Groups 2 and 3 were exposed to simulated air dives to 400 kPa (4 ata) with 45 min bottom time, every week for 7 weeks. Immediately after surfacing, the rats were anaesthetised and blood was collected from the saphenous vein. The amount of anti-HSP60 rat antibodies in the serum was analysed by enzyme linked immunosorbent assay.

RESULTS

The immunised rats (group 1) showed a significant increase in the level of autoantibodies against HSP60, whereas no autoantibodies were detected in the dived rats (group 2). The rats both immunised and dived (group 3) show no significant increase in circulating autoantibodies against HSP60. A possible explanation may be that HSP60 is expressed during diving and that cross-reacting antibodies are bound.