The prevention of occupationally-related infections in western rock lobster fishermen
Western Australian Fishing Industry Council Inc (WAFIC)
The incidence and severity of infection associated with WRL does not appear to have changed vastly since 1949, despite penicillin therapy and a heightened awareness of the infection by those in the industry. Infection may result in loss of working days. Severe cases may progess to more serious conditions such as septic arthritis and endocarditis, potentially life-threatening conditions. The inappropriate and unnecessary use of antibiotics is of great concern currently as antibiotic resistant bacteria emerge world-wide. The emphasis is now on preventing infection rather than treating it with antibiotics when it does occur. More advanced techniques for the recovery and detection of E. rhusiopathiae have been developed, including the use of selective media and a molecular method. Further study of these infections, utilising more appropriate techniques, is warranted to determine the exact role that E. rhusiopathiae has in this infection. Also, the role of other organisms causing apparent infection in fishermen of all types needs to be evaluated. This will allow preventive strategies to be developed which will, in turn, result in less infection and reduced exposure to antibiotics.
1. To determine the role that E.rhusiopathiae plays in "crayfish poisoning".
2. To determine the distribution of E.rhusiopathiae in the work environment
3. To develop interventions and strategies to reduce the incidence of "crayfish poisoning"
The Western Australian rock lobster industry is the most valuable single species fishing industry in Australia and earns $400 million annually. “Crayfish poisoning” is the common name for a painful wound infection affecting lobster fishermen and other industry workers in Western Australia. Despite improvements in working conditions and antibiotic therapies, evidence suggests that infection continues to be a source of morbidity for workers. Although rare, life threatening severe infections can result from these skin infections. Little is known about the aetiology of these infections; however, there are some similarities with another occupationally related human infection, erysipeloid, caused by Erysipelothrix rhusiopathiae. The aims of the project therefore were to elucidate the cause(s) of “crayfish poisoning”, with particular reference to E. rhusiopathiae, and to assess interventions for preventing or treating infection.
An epidemiological and microbiological investigation of “crayfish poisoning” was conducted. The potential pathogens isolated or detected from 47 suspected “crayfish poisoning” wound swabs were: Staphylococcus aureus, 22 (47%); Acinetobacter spp., 18 (38%); Streptococcus pyogenes, 11 (23%); Erysipelothrix spp., 9 (19%); Vibrio alginolyticus, 7 (15%); other Gram negative bacilli, 16 (34%). While S. aureus was the predominant organism found, Erysipelothrix was detected in 19 % of the samples. Strep. pyogenes was also frequently isolated, as was Acinetobacter spp. An objective of this project was to establish the role that Erysipelothrix plays in these skin infections. Clearly it does play a role but the natural history of this disease needs more work. Both S. aureus and Strep pyogenes are common skin pathogens. It is likely that their growth may obscure the growth of Erysipelothrix, hence our use of a molecular diagnosis. The other potential confounder, however, is time to presentation. Erysipelothrix is typically a sub-dermal infection and the skin is not broken. When the skin does beak the opportunity exists for other organisms like S. aureus and Strep pyogenes to infect the wound. The hypothesised progression of diseases therefore is Erysipelothrix infection first followed by the others. However, by the time the other organisms appear, Erysipelothrix may have disappeared. The Acinetobacter spp., Vibrio spp. and other Gram negative bacilli are likely to be environmental contaminants. This is not to say that S. aureus and Strep pyogenes are not important in the overall problem of skin infections in fishermen. They are both potentially serious pathogens.
From the epidemiological survey carried out the following information was obtained: 68% of cases were young deckhands; 52% of infections were on the fingers; 22% on the feet, 15% on the arms, and 15% on the hands; at the time of the injury 43 % were not wearing gloves; and 20 % of cases had a previous skin breach. The presenting signs were erythema (redness), cellulitis (skin breakdown), blisters, furuncles (boils) and paronychia (inflammation of the nail); and systemic symptoms presented in 33%, fever in 29% and lymphadenitis (inflammation of the lymph nodes) in 18%. Antibiotics were given in 94% of cases, mainly flucloxacillin, 56%.
To assess the distribution of Erysipelothrix spp. in the aquatic environment, a survey of 19 Australasian seafoods was conducted and methodologies for detection of Erysipelothrix spp. evaluated. Twenty-one Erysipelothrix spp. were isolated from 52 seafood parts. Primary isolation of Erysipelothrix spp. was most efficiently achieved with broth enrichment, followed by subculture onto a selective agar containing kanamycin, neomycin and vanocmycin, after 48 h incubation. Selective broth, with 48 h incubation, was the best culture method for detection of Erysipelothrix spp with polymerase chain reaction (PCR). PCR was 50 % more sensitive than culture. E. rhusiopathiae was isolated from a variety of different fish, cephalopods and crustaceans, including Western Rock Lobster (Panulirus cygnus). There was no significant correlation between the origin of the seafoods tested and the distribution of E. rhusiopathiae. An organism indistinguishable from E. tonsillarum was isolated for the first time from an Australian oyster and a silver bream. The fishermen’s work environment was heavily contaminated with Erysipelothrix spp. Overall, Erysipelothrix spp. was widely distributed, illustrating the potential for erysipeloid-like infections in fishermen. Additional isolates were also obtained from a survey of an abattoir.
The susceptibility of 60 E. rhusiopathiae strains from various sources to 13 antimicrobial agents was determined. Penicillins and cephalosporins remained active against E. rhusiopathiae and should continue to be recommended for treatment. Ciprofloxacin minimum inhibitory concentrations (MICs) were particularly low (MIC90 0.06 mg/l), offering an alternative agent for the penicillin allergic patient. E. rhusiopathiae is still resistant to vancomycin (MIC90 64 mg/l), highlighting the importance of early diagnosis of E. rhusiopathiae infection in cases of endocarditis. In addition, 31 E. rhusiopathiae isolates were tested against several commercially available home disinfectants. Most were effective in killing E. rhusiopathiae with minimum bactericidal concentrations of 0.001% for Pinocleen, and 0.03% for Domestos, Linely and the Wheelie Bin Phenyl Cleanser. These disinfectants could be used following mechanical cleaning of work environments, such as fishing boats and equipment, to reduce the risk of infection with E. rhusiopathiae.
Keywords: Western rock lobster, skin infections, Erysipelothrix rhusiopathiae.