Ph. Goullet

Epidemiological complexity of hospital aeromonas infections revealed by electrophoretic typing of esterases

An epidemiology analysis of a series of 12 Aeromonas hydrophila infections, including six of septicaemia, which occurred on several wards of one hospital during the summer of 1982 is presented. The hypothesis that the hospital water could be the source of these infections was supported by the isolation of 1-10 motile aeromonads per ml in most of the water samples collected from various points on the hospital water system. Electrophoretic esterase typing was used as an epidemiological screening method to determine the relationship between bacterial strains isolated from the patients and those from water samples. The epidemiology of A. hydrophila infection in the hospital was found to be complex. Amongst the 15 strains of A. hydrophila isolated from patients were 8 zymotypes, while amongst the 126 strains from the water samples there were 37. In some cases, several zymotypes were isolated simultaneously from the same tap water. On one ward, the same zymotype was found in 2 patients and in 2 water samples. The prophylactic measures taken in 1982-5 to avoid oral contamination of immuno-compromised patients with infected hospital water have significantly reduced the number of cases of septicaemia. This success has constituted additional retrospective evidence for the water-borne origin of these infections.

Seasonal prevalence of nosocomial Aeromonas hydrophila infection related to aeromonas in hospital water

A seasonal variation in nosocomial Aeromonas hydrophila infection was correlated with the number of aeromonas in the hospital water supply. The high summer prevalence of A. hydrophila infection coincided with periods when water counts from storage tanks were highest. The waterborne origin of these infections highlights the importance of maintaining clean water supplies, especially where storage tanks are used. Monitoring A. hydrophila in hospital water, particularly during the summer months, may prove helpful.

Esterase electrophoresis: a molecular tool for studying the epidemiology of Branhamella catarrhalis nosocomial infection

A new epidemiologic typing method based on electrophoresis of esterases had been developed for differentiating between clinical isolates of Branhamella catarrhalis. Twenty-two epidemiologically significant strains obtained from three Chest Units, a Paediatric Intensive Care Unit and a Paediatric Unit were compared with 54 randomly selected strains and 4 reference strains, including the species type strain, ATCC 25238. Thirty-four distinct zymotypes were characterized by polyacrylamide-agarose gel electrophoresis of the 80 strains. One infrequent zymotype was found in 2 neonates and another in 2 adults with nosocomial bronchopulmonary infections, suggesting the nosocomial spread of 2 outbreak strains of B. catarrhalis. A more frequent zymotype was isolated from 3 neonates with nosocomial bronchopulmonary infection and from 2 children with nosocomial rhinopharyngitis. The remaining 12 epidemiologically significant strains were of varied zymotypes. This work demonstrates that esterase electrophoresis is a suitable, readily reproducible, stable typing system applicable to the wide range of strains found in B. catarrhalis nosocomial infections.

Complexity of Pseudomonas aeruginosa infection in cystic fibrosis: combined results from esterase electrophoresis and rDNA restriction fragment length polymorphism analysis.

Esterase electrophoretic typing and restriction fragment length polymorphism of ribosomal DNA regions (ribotyping) were used to differentiate 102 Pseudomonas aeruginosa clinical isolates obtained from chronic lung infection in 23 patients with cystic fibrosis (CF) and two reference strains (including the type strain ATCC 10145). Twenty-five zymotypes were obtained with the former method and 16 ribotypes with the latter. Combination of the two typing systems led to the finding of 30 different types. Our data highlights the physiopathological complexity of P. aeruginosa infection in CF as, in six individual cases, several types were found among isolates from a given patient. On the other hand, two unique types were found in two and three patients respectively, raising the possibility of cross-infections.

Correlation between electrophoretic types B1 and B2 of carboxylesterase B and host-dependent factors in Escherichia coli septicaemia.

Electrophoretic types B1 and B2 of carboxylesterase B produced by strains of Escherichia coli isolated from 100 septicaemia cases were correlated with alpha-haemolysin and mannose resistant haemagglutinin (MRHA) production and with clinical data including eventual underlying diseases, origin of septicaemia and evolution. Electrophoretic type B2 was phenotypically linked with alpha-haemolysin and MRHA production. The proportion of type B2 isolates varied significantly with occurrence of an underlying illness (45% for patients without an underlying disease and 22% for compromised patients) and with the site of origin of the septicaemia (40% for those of urinary origin and 18% for infection of digestive origin). In the former infections, type B2 isolates were obtained in the majority from male patients while type B1 isolates predominated in women. The septicaemias associated with type B1 were characterized by a lower proportion of isolates producing alpha-haemolysin and MRHA and by a greater frequency of septic shock and death than those associated with type B2. These facts emphasize the importance of host-dependent factors in E. coli septicaemia.

Epidemiology of Staphylococcus aureus in patients with cystic fibrosis

Seven hundred and thirty-four isolates of Staphylococcus aureus, recovered from the sputum of 238 cystic fibrosis patients in six French hospitals, were characterized by esterase electrophoretic typing, capsular polysaccharide serotyping and phage typing and tested against 14 antibiotics for sensitivity. Thirty-four esterase electrophoretic types were found with a genotypic diversity coefficient of 0.91. Five hundred and forty-eight (78.7%) isolates produced capsular polysaccharide and 350 (50.3%) were type 8. Four hundred and sixty isolates (66.6%) were phage typable and 202 (28.2%) were lysed by group III bacteriophages. No esterase electrophoretic type, capsular type or phage type was specific to cystic fibrosis. Isolates belonged to a wide range of types, similar to strains acquired outside hospitals. Eighty-five patients had three or more consecutive isolates over at least 6 months. The ability of S. aureus to persist for long periods of time has been demonstrated in 73% of them. Methicillin-resistance was encountered among 73 strains (9.8%) which were also multiresistant. Two hundred and eighty-nine (39.9%) strains were sensitive to all antibiotics tested except to penicillin. Pristinamycin and co-trimoxazole were the most effective antibiotics. These results could contribute to the elaboration of a rational approach to the prophylaxis and therapy of respiratory staphylococcal infections in cystic fibrosis patients.

Nosocomial Serratia marcescens individualized by five typing methods in a regional hospital

The relationships between 69 isolates obtained from 26 patients who were affected by two Serratia marcescens hospital outbreaks occurring in the urology and postnatal wards, were examined by five typing methods for epidemiological purposes. Serotyping, antibiotic resistance profile and electrophoretic analysis of enzymes identified three groups of isolates, while biotyping and bacteriocin typing identified only two. These surveys allowed us to demonstrate the existence of independent episodes of cross-infection among patients of each ward.

Purification and properties of carboxylesterase B of Escherichia coli

Carboxylesterase B produced by Escherichia coli was purified 1,350-fold with a recovery of 12% by successive gel filtrations, DEAE-trisacryl, phenyl-Sepharose chromatography and preparative electrophoresis. The purified enzyme was found to be homogeneous, as judged by a single precipitation line in Ouchterlony double diffusion in an experiment with homologous antiserum. The apparent molecular weight determined by gel filtration and the isoelectric point determined by electrofocusing were 57,000 and 4.6, respectively. Using acetate, propionate and butyrate esters of 1-naphtol, it was observed that elongation of the acyl carbon chain resulted in a progressive increase in velocity of ester hydrolysis. The apparent Km for 1-naphtyl acetate was found to be 0.25 mM. The enzyme was maximally active at pH 7.4 and was found to be unstable below pH 5. Hydrolytic activity was preserved after heat treatment for 30 min at 60 degrees C, but was abolished by heating for 10 min at 70 degrees C. The enzyme was strongly inhibited by low concentrations of di-isopropyl fluorophosphate. This suggested that a serine residue is required for catalytic activity. Esterase was unaffected by tosyl-L-lysin chloromethylketone, iodoacetamide, 4-hydroxy-mercuribenzoate and EDTA. Using antiserum against purified carboxylesterase B of E. coli, significant immunological cross-reactions were observed between this antigen and carboxylesterase B produced by Shigella flexneri, S. boydii and S. sonnei.

Correlation between electrophoretic types B1 and B2 of carboxylesterase B and sex of patients in Escherichia coli urinary tract infections.

One hundred and sixty-eight strains of Escherichia coli isolated from 84 men and 84 women who had urinary tract infections (134 cases) or bacteremia of urinary tract origin (34 cases) were assessed for their carboxylesterase B electrophoretic types B1 and B2, alpha-haemolysin production, the presence of mannose resistant haemagglutinin (MRHA) and antibiotic susceptibility. Electrophoretic type B2 was phenotypically linked with alpha-haemolysin and MRHA productions. The strains isolated from males were more frequently of type B2, haemolytic and both haemolytic and haemagglutinating than those isolated from females. The strains isolated during bacteremia were more frequently haemolytic and haemagglutinating than those obtained from urinary tract infections. Type B1 strains were more frequently resistant to antimicrobial agents than type B2 strains. The results reinforced the distinction, in terms of virulence and antibiotic sensitivity, between B1 and B2 strains and demonstrated the influence of the sex of patients on the host-parasite interaction during urinary tract infections.

Genetic heterogeneity in methicillin-resistant strains of Staphylococcus aureus revealed by esterase electrophoretic polymorphism

136 methicillin-resistant strains of Staphylococcus aureus recovered from hospitalized patients in 18 countries were characterized by electrophoretic mobilities of three types of esterases. These were defined by their ranges of activity toward five synthetic substrates and their resistance to di-isopropyl fluorophosphate. Fourteen zymotypes were distinguished. Two, designated as 6 and 14, were found in 53 and 50 strains, respectively. Genetic diversity coefficients were lower for strains from France and from other European countries (H = 0.47 and 0.53, respectively) than for strains from North America (H = 0.79). On the basis of electrophoretic polymorphism of esterases, our work provides evidence that methicillin-resistance is expressed in genetically different strains. Variations in esterase electrophoretic pattern within methicillin-resistant strains of S. aureus can make a significant contribution to the study of their epidemiology.