Molecular typing and long-term comparison of clostridium difficile strains by pulsed-field gel electrophoresis and PCR-ribotyping.

Thirty-two related and 68 unrelated isolates of Clostridium difficile, isolated in different Italian hospitals since 1987, were analysed by PFGE and PCR-ribotyping to investigate their genetic relatedness. The isolates were classified into 28 groups by PFGE and 20 ribotypes by PCR-ribotyping. A single clone of C. difficile was recognised as the cause of three geographically and chronologically distant outbreaks. The correlation between PFGE and PCR-ribotyping results was good, with agreement for 77 (84%) of the 92 isolates typed by both methods. However, among sporadic isolates the discriminatory power of PFGE was more evident. Eight isolates that were untypable by PFGE could be analysed by PCR-ribotyping. The dendrograms generated showed that the genetic relatedness of the C. difficile isolates obtained by both techniques was comparable. The majority of the isolates in recent years appeared to be genetically unrelated to isolates from past infections. However, two clonal groups identified in all time periods had a common origin and this seems to indicate that they share some advantageous biological characteristics. The constant monitoring of C. difficile epidemiology will allow acquisition of further important data on this nosocomial pathogen.

Immunogenicity issues in the quality control of the new acellular pertussis vaccines.

Over the last few years our laboratory has been assessing the consistency of production of different batches of acellular pertussis vaccines to be marketed in Italy. Central to this is immunogenicity assay of the lots under control compared with those of a reference vaccine with documented clinical efficacy.However, the current assays based on the assessment of antibody (Ab) response in the mouse are unrelated to mechanisms of protection in children. The absence of a clear correlation between Ab responses and protection has also been documented in recent clinical trials. On this basis, we are currently considering the possibility of adding to the established criteria of immunogenicity in mice based on Ab responses, information from studies on cell-mediated immune responses to the vaccine constituents.

Oligonucleotide probes for detection of cephalosporinases among Bacteroides strains.

Two oligonucleotide probes selected from the sequences of cepA and cfxA genes, respectively, were used to detect beta-lactamase production among strains of the Bacteroides fragilis group. By using these probes, colony hybridization was shown to be a specific and rapid method for identifying the more prevalent beta-lactamase, CepA, and the rarer CfxA enzyme among B. fragilis strains.

A 5-year immunization field trial against hepatitis B using a Chinese hamster ovary cell recombinant vaccine in French Polynesian newborns: results at 3 years.

A hepatitis immunization field trial, using a Chinese hamster ovary (CHO) cell recombinant vaccine, was implemented for newborns in the Austral archipelago of French Polynesia in 1988. Three different schedules were used: (1) four vaccine doses at months (M) M0, M1, M2 and M12; (2) three vaccine doses at M0, M1 and M6; and (3) three vaccine doses at M0, M1 and M12. The programme evaluation was performed yearly at fixed dates, i.e. October-November 1989, 1990 and 1991. After the third year, of the 582 children who received one or more doses of vaccine, four were HBsAg carriers. After one or two doses, 88 and 98%, respectively, had seroconverted for at least one of the two measured antibodies, anti-HBs or anti pre-S2. After three doses, seroconversion rates and geometric mean anti-HBs titres were, respectively, 94% and 187 mIU ml-1 using schedule M0, M1, M2; 95% and 507 mIU ml-1 using schedule M0, M1, M6 and 96% and 476 mIU ml-1 using schedule M0, M1, M12. After four doses (M0, M1, M2, M12) the corresponding results were 99% and 1518 mIU ml-1. One of the 16 vaccinated neonates born to HBsAg/HBeAg-positive mothers was an HBsAg carrier, implying a protective rate for the prevention of perinatal transmission of 93%. Overall, these results indicate that, in field conditions, indiscriminate vaccination of newborns with a CHO-recombinant vaccine without hepatitis B immunoglobulin (HiBG) resulted in high immunogenicity. Final evaluation in 1993-1994 will permit confirmation of the effectiveness of the two three-dose vaccine schedules.

Ivermectin plus diethylcarbamazine: an additive effect on early microfilarial clearance.

The effects of ivermectin, diethylcarbamazine (DEC), and the combination of both drugs on levels of microfilaremia (mf) were studied in 30 male Polynesian Wuchereria bancrofti carriers. Microfilarial densities were measured 30 min (H1/2), 1 hr (H1), and 2, 4, 8, 24, and 96 hr (H2, H4, H8, H24, and H96) after supervised single doses of ivermectin plus DEC (400 micrograms/kg plus 1 mg/kg, respectively, 400 micrograms/kg plus 3 mg/kg, respectively, and 400 micrograms/kg plus 6 mg/kg, respectively), DEC (6 mg/kg) alone, and ivermectin (400 micrograms/kg and 100 micrograms/kg, respectively) alone given to six groups of five patients each. The results showed that 1) DEC alone or combined with ivermectin induced a rapid clearance of mf after drug intake; at H1/2, the number of circulating microfilariae was reduced to 16%, 8%, 28%, and 31%, respectively, of pretreatment values in the groups receiving ivermectin plus DEC (400 micrograms/kg plus 1 mg/kg, 400 micrograms/kg plus 3 mg/kg, and 400 micrograms/kg plus 6 mg/kg) and DEC (6 mg/kg) alone; 2) ivermectin alone induced a rapid increase of mf densities during the first 2 hr, followed by a sharp decrease from H4 to H96; and 3) between H8 and H96, mf clearance was almost complete with the combination of ivermectin and DEC. A comparison among groups did not show any synergistic interaction between ivermectin and DEC on the clearance of microfilaria, with the effect of each drug being additive to each another.

Leprosy in French Polynesia. Epidemiological trends between 1946 and 1987.

The analysis of computerized data (OMSLEP system) on patients from French Polynesia followed since 1940 has shown a decrease in the mean annual detection rates for leprosy, all forms combined, from 24.73 per 100,000 inhabitants in 1946 to 8.1 per 100,000 in 1987 (y = -0.49 x + 45.83; p < 0.05). In fact, the decrease was significant (y = -1.18 x + 83.54; p < 0.05) during the first half of the study period (1946-66), but not during the second half (1967-87). Similarly, a significant decrease in all of the specific mean annual detection rates (according to the form of leprosy and to the sex and age of patients), in the proportion of multibacillary patients among the total of newly detected cases, and in the proportion of all patients with disabilities at the onset of leprosy was observed only during the first half of the study period (1946-66). Nevertheless, when comparing age-specific cumulative detection rates, calculated by 10-year age groups over the period 1946-66, to those of the period 1967-87, an ageing of the leprosy population was noted. Finally, the decrease of mean annual detection rates was greater in the smaller populations of remote islands than in the population of Tahiti, the main island, where 70% of the total population were living during the study period. This decline was shown to correspond to an effective improvement of the leprosy situation which could be attributed, among other factors (such as economic development and systematic BCG vaccination), to the implementation of a control programme for leprosy in 1950. The introduction in 1982 of multidrug therapy for all patients suffering active leprosy has raised the hope of a subsequent decline of leprosy in French Polynesia in the near future.

Compared efficacy of repeated annual and semi-annual doses of ivermectin and diethylcarbamazine for prevention of Wuchereria bancrofti filariasis in French Polynesia. Final evaluation.

In October 1989, 58 apparently healthy Polynesian Wuchereria bancrofti carriers, in whom microfilarial (mf) density was greater than or equal to 100 mf/ml, were randomly allocated to treatment groups receiving single doses of either ivermectin at 100 mcg/kg or diethylcarbamazine (DEC) at 3 and 6 mg/kg. Six months later, half of the carriers initially treated with ivermectin 100 mcg/kg or DEC 3 mg/kg were given a second similar dose while the rest were given a placebo. Six months later again, all of the carriers received a last treatment dose similar to the initial one. The results observed during the 12-month period which followed this last treatment have confirmed that (i) in terms of immediate clearance or complete negativation of microfilaremia, the efficacy of ivermectin is higher than that of DEC (at dosage of 3 or 6 mg/kg), (ii) DEC is more effective than ivermectin in sustaining the reduction of microfilaremia over a longer period of time and (iii) the efficacy of repeated single doses of either DEC 3 mg/kg or ivermectin 100 mcg/kg is much higher when given semi-annually than annually.(ABSTRACT TRUNCATED AT 250 WORDS)

Dengue 1 epidemic in French Polynesia, 1988-1989: surveillance and clinical, epidemiological, virological and serological findings in 1752 documented clinical cases.

An epidemic of dengue 1 occurred in French Polynesia in December 1988 and June 1989. This paper records (i) the trend of the outbreak and its surveillance and (ii) the clinical, epidemiological and virological data obtained from 1752 documented cases. The epidemic reached its peak in February in Tahiti Island, 7 weeks after its recognition. Among 6034 suspect cases reported by sentinel physicians, 60.3% were < 20 years old. The illness was classical dengue. No fatality or case of dengue haemorrhagic fever/dengue with shock syndrome was reported. Of 4792 patients subjected to laboratory testing, 41% were confirmed as positive. The serological attack rate was c. 40%. The estimated number of dengue infections in the Windward Islands was about 20,000. Transmission was associated with Aedes aegypti. Study of documented cases showed a higher confirmation rate in both the civilian population < 15 years old (46.5%) and the susceptible French military population (47.6%) than in older civilians (31.1%, P < 0.05). Furthermore, primary dengue infections were predominant in both of the first 2 groups. The diagnosis was mostly confirmed (i) by virus isolation on day < 5 of illness and (ii) by detection of immunoglobulin (Ig) M on day > or = 5 of illness. The study showed that adequate surveillance of an epidemic requires both clinically and laboratory-based systems.

[Goiter in Tahiti]. / Le goître à Tahiti.

The authors report on a prospective study about goitre in French Polynesia carried out in 1989, dealing with epidemiology and disease characterization in 39 patients. 1. Epidemiology of goitre in Tahiti; In schools: 517 children (236 boys and 281 girls) aged from 10 to 15. Prevalence rate is 1.55 p.c. (8/517); Adults: 226 adults (112 males and 114 females) aged from 50 to 65. Prevalence rate is 4.42 p.c. (10/226). 2. Case study on 39 Polynesian patients (38 females and 1 male) living in Tahiti (mean age: 35.6 years old) showing euthyroidic goitre, detected from 1989 April 1st and October 31; Goitre did not present in Tahiti any particularity. It is a pathology mainly feminine, at low evolution and late local consequences; In 3/4 of the cases, goitre is visible and more it is voluminous more modules are present; There is no iodine deficiency, and the mean value of iodine excretion (536 mcg/24 h) is very high in comparison with what is described in the literature; Presence of a high thiocyanatemia (greater than 100 mmol/l) is found in 1/4 of the patients; There is no correlation between consumption of foods well-known as cyanogenical ones and the level of thiocyanatemia; There is a correlation between the rate of thiocyanatemia and tabagism.

Single versus repeated doses of ivermectin and diethylcarbamazine for the treatment of Wuchereria bancrofti var. pacifica microfilaremia. Results at 12 months of a double-blind study.

In October 1989, 58 apparently healthy Polynesian Wuchereria bancrofti carriers in whom microfilarial (mf) density was greater than or equal to 100 mf/ml were randomly allocated to treatment groups receiving single doses of either ivermectin at 100 mcg/kg or diethylcarbamazine (DEC) at 3 and 6 mg/kg. Six months later, half of the carriers initially treated with ivermectin 100 mcg/kg or DEC 3 mg/kg were given a second similar dose while the rest were given a placebo. By day 360 (6 months after retreatment), comparison of adjusted geometric mean mf counts per group indicated that (i) among the 3 treatments given once a year the DEC 6 mg/kg dose resulted in the highest efficacy, (ii) nevertheless, regarding either ivermectin 100 mcg/kg or DEC 3 mg/kg, 2 successive doses resulted in higher efficacy than one annual dose and (iii) though no significant difference could be evidenced between efficacy of ivermectin 100 mcg/kg and DEC 3 mg/kg given twice a year, DEC seemed to sustain the mf reduction for a longer period of time. During the 3 days following retreatment, adverse reactions (mild to moderate) were observed in 46% of carriers treated with microfilaricidal drugs and in 20% of those treated with placebo. These results suggest that single dose therapy with either DEC or ivermectin is safe and effective for prevention of lymphatic filariasis due to Wuchereria bancrofti in French Polynesia. The real impact on transmission by the vector, Aedes polynesiensis, of the complete negativation of microfilaremia observed during the previous part of the trial in carriers treated with ivermectin should be evaluated in a community-based trial including entomological study.(ABSTRACT TRUNCATED AT 250 WORDS)

One year evaluation of immunogenicity conferred by a Chinese hamster ovary cell recombinant hepatitis B vaccine in a French Polynesian newborn immunization programme.

In 1988, a hepatitis immunization programme, using a Chinese hamster ovary (CHO) cell recombinant vaccine, was implemented for newborn children in the Austral archipelago (French Polynesia). Three different schedules were used: (i) 4 vaccine doses at months (M) 0, M1, M2 and M12; (ii) 3 vaccine doses at M0, M1, M6; and (iii) 3 vaccine doses at M0, M1, M2. Results at the one year follow-up may be summarized as follows. Of 197 infants who received one or more doses of CHO-recombinant vaccine, (i) none was an HBsAg carrier; (ii) 89.5% had anti-HBs-antibody titres greater than 10 miu/ml; and (iii) 95.9% had seroconverted for at least one of the 2 antibodies studied (anti-HBs or anti-pre-S2). After 2 doses (M0, M1), anti-HBs seroconversion rate and geometric mean titre were, respectively, 82.6% and 98.47 miu/ml. After 3 doses, seroconversion rates and geometric mean titres were, respectively, 91.1% and 200.59 miu/ml using schedule M0, M1, M2, and 100% and 1253.4 miu/ml using the M0, M1, M6 schedule. None of the 7 vaccinated neonates born to HBsAg/HBeAg positive mothers was found to be an HBsAg carrier. These preliminary results indicate that, in field conditions, vaccination with a CHO-recombinant vaccine resulted in high immunogenicity.

Prevalence of hepatitis B virus infection in the Austral archipelago, French Polynesia: identification of transmission patterns for the formulation of immunization strategies.

A sero-epidemiological survey of hepatitis B virus (HBV) infection in a randomly selected sample of 957 persons from the population of the Austral Island group in French Polynesia was conducted as a first step before developing an immunization programme strategy. Prevalence rates of HBsAg ranged from 3.09% to 27% in the different islands of the group with a weighted mean of 10.48%, while the prevalence rate for at least one marker ranged from 46.91% to 81.03% with a weighted mean of 64.12%. In the 0-11 months and 1-4 years age groups, 2.08% and 10.57%, respectively, of the children were HBsAg carriers. These findings, when compared to the mean population carrier rate of 10.48%, suggest that HBV transmission occurred mostly after the first year of life. The highest prevalence rate for HBeAg positivity was in the 5-19 years age group (more than 40% of the HBsAg carriers were HBeAg positive), suggesting that contagiousness was greatest in childhood and adolescence. HBsAg was found in 11.45% of women of child-bearing age and HBeAg in 19.09% of women positive for HBsAg. It is concluded that immunization of newborns and infants, using vaccine alone, should be the most effective strategy for reducing HBV infection in the Austral Islands archipelago.

Clostridium difficile in preterm neonates.

Stool specimens from premature neonates over the first month of life were examined for the presence of toxigenic Clostridium difficile and to evaluate a possible correlation between colonization and bowel disorders or prior antibiotic administration. Results showed a high isolation rate (63%) of Clostridium difficile with similar incidence in infants treated or not with antibiotics and with or without bowel disorders. Differentiation among strains according to SDS-PAGE, antibiotic susceptibility patterns and toxin production were useful to reveal cross-contamination. Both toxin-producing and non toxigenic strains were found in the infants' intestines. However, toxigenic strains were only present in infants suffering from bowel disorders and thus treated with oral antibiotics, suggesting that these factors may favour colonization by toxigenic strains.

Comparison of the in vitro activities of teicoplanin and vancomycin against Clostridium difficile and their interactions with cholestyramine.

The in vitro activity of teicoplanin was compared with that of vancomycin against fecal isolates of Clostridium difficile. All strains were susceptible to both antibiotics, but teicoplanin was fourfold more active than vancomycin. Cholestyramine was found to bind teicoplanin almost completely, reducing its activity to nondetectable levels.