Multiple typing for the epidemiological study of the contamination of broilers with Salmonella from the hatchery to the slaughterhouse.

Eighteen Belgian broiler flocks were followed from the hatchery to the slaughterhouse by a multiple typing approach (sero-, geno-, and phage types) for the investigation of the transmission of Salmonella and its subtypes. For 12 of the 18 flocks, there was no correlation between the serotypes found preharvest and those isolated from the feces in the transport crates and on the carcasses in the slaughterhouse. Serotypes found in the crates were usually also found on the carcasses. In 5 of the 10 flocks with Salmonella-positive broilers, complex contamination patterns with the involvement of different serotypes, genotypes, or both were revealed. In two of these flocks (flocks 8 and 9), the Salmonella Enteritidis contamination of the broilers could be traced to the hatchery. In flock 9, evidence was found for the acquisition, during rearing, of a megaplasmid in the Salmonella Enteritidis strain. In the other three positive flocks (flocks 6, 7, and 10), the environment and movable material (e.g., footwear) played a determining role in the infection and shedding pattern of the broilers. For flocks 6 and 7, reared consecutively in the same broiler house, a persistent Salmonella Hadar geno/phage type predominated in the preharvest period, while another Salmonella Hadar geno/phage type was found in the house or the environment but never in the broilers. Only for the above-mentioned five flocks were the same strains that were found preharvest also recovered from the carcasses, although these strains were not predominant on the carcasses, with the exception of one flock (flock 10). In conclusion, it can be said that most of the time, Salmonella strains that contaminate Belgian broiler carcasses do not predominate in the preharvest environment.

Risk factors for HIV seropositivity in selected urban-based Rwandese adults.

In January 1987, HIV antibodies were detected by means of an immunoenzymatic assay, indirect immunofluorescence and Western blot in 52 out of 302 male urban-based professionals and in 28 out of 150 health workers in Kigali, Rwanda. Univariate analysis showed an association between HIV seropositivity and a history of sexually transmitted diseases (STD), blood transfusion, medical injections for treatment of STD, and medical injections for treatment of febrile illnesses. However, injection related to treatment of other conditions were not associated with HIV seropositivity. Among health workers, no association between HIV seropositivity and professional or accidental exposure to HIV-infected patients or to their body fluids was identified. Discriminant analysis showed that HIV seropositivity was associated only with a history of STD and with a history of blood transfusion. In central Africa, a history of STD and a history of blood transfusion should be considered as risk factors for HIV seropositivity. Medical or accidental injections do not seem to play a major role in the transmission of HIV among adults in central Africa.

HIV antibodies in a remote rural area in Rwanda, Central Africa: an analysis of potential risk factors for HIV seropositivity.

Detection of HIV antibodies by means of an immunoenzymatic assay, an indirect immunofluorescence technique and Western blot was attempted on 375 serum samples collected in the Murunda area, a remote rural area situated in Rwanda, central Africa. Two out of 147 (1.4%) adults from a strict rural area, five out of 59 (8.5%) adults from an adjacent market place, and 49 out of 169 (30%) STD clinic attenders from the same area were HIV seropositive. In the first two groups, HIV seropositivity was associated with a history of sexually transmitted disease (STD) in the previous 2 years (P less than 0.001) and with a history of travel to a Rwandese urban centre in the previous 5 years (P less than 0.05). This study suggests that HIV seroprevalence is low in rural central Africa compared with urban centres. Risk factors for HIV seropositivity are similar in rural and urban-based adults in Rwanda, i.e. heterosexual promiscuity and STDs. Many HIV seropositive rural subjects from this study are likely to have acquired HIV infection through sexual contacts in Rwandese cities.

PIP: 375 serum samples collected from youth and adults in Murunda, a remote rural area in Rwanda, were analyzed for antibodies to human immunodeficiency virus (HIV). Study subjects were drawn from 3 selected populations: those from the village of Rulimba, a strictly rural area; adults from Gisiza, an adjacent rural market place that is connected by roads to 2 other cities; and patients from the same district who attended the Murunda health center for treatment of a sexually transmitted disease during the study period. The prevalence of HIV seropositivity was 2/147 (1.4%) in the strictly rural group, 5/59 (8.5%) in the market place area, and 49/169 (30%) among patients receiving treatment for sexually transmitted diseases. No significant differences existed between male and female subjects in terms of HIV seropositivity. HIV seropositivity was also associated with a history of venereal diseases in the market place sample. These results suggest that Rwanda's rural population (93%) is at lower risk of HIV infection that the urban population. Where HIV infection does exist in rural areas, it is transmitted mainly by heterosexual contact with persons from urban centers. The relatively high rate of HIV infection observed in adults living in a rural market place accessible from most of the Rwandan main cities, together with the association between HIV seropositivity and past residency or travel in urban centers, indicates that most of the rural-based seropositive adults identified in this study were infected elsewhere. These findings also contradict the popular assumption that HIV was present in an unrecognized form for many years in rural Central Africa.

Evaluation and simplification of the World Health Organization clinical case definition for paediatric AIDS.

The World Health Organization (WHO) clinical case definition for paediatric AIDS was tested during a 1-month period on 221 consecutive hospitalized children in Kigali, Rwanda. Relevant clinical features not included in the WHO case definition were also evaluated. Thirty-four out of the 221 children (15.4%) were HIV seropositive. Although the specificity of the WHO case definition was high (92%), the sensitivity and the positive predictive value (PPV) were low (41 and 48%, respectively). The following individual signs had a PPV at least equal to the complete WHO case definition: chronic diarrhoea (47%), respiratory distress secondary to lower respiratory tract infection (50%), oral candidiasis (53%), parotitis (67%), generalized lymphadenopathy (88%), and herpes zoster infection (100%). When logistic regression analysis was done on the nine variables included in the WHO case definition, confirmed maternal infection was the best predictive variable for HIV seropositivity in children (P less than 10(-5). We further excluded the serological status of the mother from the analysis and performed a stepwise logistic regression analysis on the 18 clinical signs and symptoms for which information had been collected. Those signs and symptoms contributing the most to the regression were: respiratory distress, chronic diarrhoea and generalized lymphadenopathy. Based on these findings, we propose a simplified clinical case definition for paediatric AIDS in Africa with better sensitivity, specificity and PPV than the WHO case definition. Further work is needed using this approach to develop case definitions useful for epidemiological surveillance and for case management.

PIP: The World Health Organization (WHO) clinical case definition for pediatric acquired immunodeficiency syndrome (AIDS) was evaluated over a 1-month period in 221 consecutive hospitalized children in Kigali, Rwanda. The median age of the children studied was 18 months (range, 1 month-14 years); 55% were boys. 34 (15%) of these 221 children were seropositive for the human immunodeficiency virus (HIV). Although the specificity of the WHO case definition was high (92%), its sensitivity was only 41% and the positive predictive value was 48%. The following individual signs had a positive predictive value at least equal to the complete WHO case definition: chronic diarrhea (47%), respiratory distress secondary to lower respiratory tract infection (50%), oral candidiasis (53%), parotitis (67%), generalized lymphadenopathy (88%), and herpes zoster infection (100%). Logistic regression analysis on the 9 variables included in the WHO case definition indicated that confirmed maternal HIV infection was the best predictive variable for HIV seropositivity in children. When maternal serological status (rarely available in Rwanda) was excluded from the analysis and a stepwise logistic regression analysis was performed on the 18 clinical signs and symptoms for which data had been collected, respiratory distress, chronic diarrhea, and generalized lymphadenopathy emerged as the signs contributing the most. On the basis of these findings, a simplified clinical case definition of pediatric AIDS is proposed for settings where resources are limited and HIV seroprevalence is high. According to this definition, pediatric AIDS should be suspected in a child presenting with 1 or both of the following clinical signs: respiratory distress secondary to lower respiratory tract infection and/or generalized lymphadenopathy. However, it is necessary to test this definition on a larger scale in Central Africa and in other parts of the world with different rates of HIV seroprevalence.

Twelve year observation of primary and secondary antibiotic-resistant Helicobacter pylori strains in children.

BACKGROUND: The effectiveness of Helicobacter pylori eradication regimens is influenced by antibiotic susceptibility of infecting strains. Data concerning antibiotic resistance in children are limited. We report the evolution of primary and secondary resistance in a series of Belgian children during the last 12 years. PATIENTS AND METHODS: From 1989 through 2000, H. pylori gastritis was diagnosed in 569 children, and antibiotic susceptibility tests were performed in 555. Eradication, using different schemes, failed in 128 of 457 treated children. After eradication failure antibiotic susceptibility determination was performed in 87 of 128. Comparison of antibiotic susceptibility of strains isolated from the gastric body and from the antrum was performed in 238 samples. RESULTS: Resistance to amoxicillin was not observed. The rate of primary resistance to nitroimidazole derivatives was 18.0% (101 of 555) and remained constant throughout this period, whereas primary resistance to macrolides increased from an average of 6.0% (range, 0 to 10%) before 1995 to 16.6% (range, 10 to 25%, P < 0.001) thereafter. Antibiotic consumption in Belgium, especially macrolides, did not show important fluctuations during the study period. Secondary resistance developed in 39 of 87 patients (46%). Strains isolated from different gastric locations show identical susceptibility testing in all but 5 of 238. CONCLUSIONS: Resistance of H. pylori to macrolides increased in our pediatric population which did not appear to correlate with macrolides prescription habits in our country. After eradication failure acquired secondary resistance was observed in one-half of the patients.

A competitive immunosorbent assay for the detection of heat-stable enterotoxin of Escherichia coli.

A competitive ELISA procedure for the detection of Escherichia coli heat stable enterotoxin (ST) with monoclonal antibody has been developed. This test is 10 times more sensitive than the suckling-mouse bioassay and it is specific, simple and cheap. A set of 882 strains of E. coli isolated from man were tested both by ST-ELISA and suckling-mouse bioassay, the latter serving as the reference method. Positive results in both tests were obtained with 152 strains. The remaining strains gave negative results in both tests, with the exception of two strains, known to be ST producers, that gave negative results in the suckling-mouse assay, but gave positive results by the ELISA method.

Differentiated Caco-2 cells as a model for enteric invasion by Campylobacter jejuni and C. coli.

A collection of 44 Campylobacter isolates (37 C. jejuni and seven C. coli) from children with colitis (21 strains) or watery diarrhoea (23 strains) was analysed for toxin production, association with HeLa cells, and invasion of differentiated Caco-2 cell cultures. There was no obvious association of clinical symptoms with species, biotype or enterotoxin production. All colitis strains and most of the isolates from watery diarrhoea were cytotoxic for Chinese hamster ovary cells. Measurements of bacterial association indices with HeLa cells varied with time, and were considered to be unreliable for discriminating between isolates from the two diagnostic groups. Statistically significant differences were observed between the two groups (all colitis strains and 65% of strains from non-inflammatory diarrhoea) with respect to invasion of both HeLa and Caco-2 cell monolayers. However, among the strains from non-inflammatory diarrhoea that did invade, numbers of internalised bacteria were similar to the range observed for colitis strains. Of the colitis strains, 86% were able to transcytose through polarised Caco-2 monolayers grown on filters, compared with 48% of isolates from non-inflammatory disease. We propose the use of Caco-2 cells as a model for studying invasion of intestinal epithelia by C. jejuni and C. coli.

Campylobacter, from obscurity to celebrity.

After its successful isolation from stools in the 1970s, Campylobacter jejuni has rapidly become the most commonly recognised cause of bacterial gastroenteritis in man. Reported cases of human campylobacteriosis represent only a small fraction of the actual number. In industrialised countries, the incidence of C. jejuni/Campylobacter coli infections peaks during infancy, and again in young adults aged 15-44 years. Acute self-limited gastrointestinal illness, characterised by diarrhoea, fever and abdominal cramps, is the most common presentation of C. jejuni/C. coli infection. The introduction of selective media has made the diagnosis of Campylobacter enteritis a simple procedure. In general, Campylobacter enteritis is a self-limiting disease which seldom requires antimicrobial therapy, although one in 1000 infections may lead to the Guillain-Barré syndrome. In industrialised countries, most infections are acquired through the handling and consumption of poultry meat. In developing countries, where the disease is confined to young children, inadequately treated water and contact with farm animals are the most important risk factors. Many infections are acquired during travel. Fluoroquinolone resistance has been reported in C. jejuni since the late 1980s in Europe and Asia, and since 1995 in the USA. The use of fluoroquinolones to treat animals used for food has accelerated this trend of resistance. In Australia, where fluoroquinolones have not been licensed for use in food production animals, C. jejuni remains susceptible to fluoroquinolones. The public health burden of Campylobacter spp. other than C. jejuni/C. coli remains unmeasured. Better diagnostic methods may reveal the true health burden of these organisms.

Evaluation of the ProSpecT Microplate Assay for detection of Campylobacter: a routine laboratory perspective.

OBJECTIVES: To evaluate the use of the new enzyme-linked immunosorbent assay, the ProSpecT Campylobacter Microplate Assay (Alexon-Trend, Minneapolis, MN, USA), which allows 2-h detection of both Campylobacter jejuni and Campylobacter coli antigen directly in stool specimens. METHODS: Over 4 months, all stool samples preserved in Cary-Blair medium, or fresh specimens, from non-hospitalized children and HIV-infected patients (adults and children), submitted to our laboratory were evaluated with the ProSpecT Campylobacter Microplate Assay. Results were compared with those obtained by routine culture methods using both a specific medium and a filtration method for the recovery of Campylobacter spp. RESULTS: Of the 1205 stool specimens cultured, 101 were found to be positive for either C. jejuni or C. coli, giving an overall recovery rate of 8.38%. Ninety samples were positive by both culture and ProSpecT Campylobacter Microplate Assay, and 11 were positive by culture only, giving a sensitivity of 89.1%. In addition, of 1104 samples negative by culture, 25 were initially positive by ProSpecT Campylobacter Microplate Assay. We found no cross-reaction with other bacterial enteropathogens isolated from stool specimens. These results thus confirm a high specificity (97.7%) for both C. jejuni and C. coli. The positive and negative predictive values found were 78.3% and 99%, respectively. There was no statistically significant difference in sensitivity and specificity if the stool was fresh or preserved with Cary-Blair medium. CONCLUSION: These data suggest that the ProSpecT Campylobacter Microplate Assay is a rapid and easy-to-use test for the detection of both C. jejuni and C. coli in stool specimens. It could be used for patients for whom early antibiotic therapy is needed or for epidemiologic studies.

Campylobacter: pathogenicity and significance in foods.

In the last 10 years Campylobacter jejuni has emerged as the most frequent cause of bacterial gastroenteritis in man. Acute enterocolitis, the most common presentation of C. jejuni infection, can affect persons of all ages. C. jejuni has been found in virtually every country where investigations have been carried out. The frequent finding of dysenteric stools suggests that mucosal damage due to an invasive process analogous to that seen in shigellosis is important in the pathogenesis. Campylobacteriosis in man is mainly a foodborne infection in which foods of animal origin, particularly poultry, play an important role. Epidemiological investigations have demonstrated a significant correlation between the handling and consumption of poultry meat and the occurrence of Campylobacter enteritis. Barbecues appear to present special hazards for infection, because they permit easy transfer of bacteria from raw meats to hands and other foods and from these to the mouth. Milk is sometimes found to be contaminated and consumption of raw milk has caused several outbreaks of campylobacteriosis. Campylobacter can remain viable in fresh cheese for only a short period of time. The organism is also found in shellfish, such as clams. Campylobacter is probably very vulnerable to factors such as high temperatures and dry environments, and also to the presence of oxygen in atmospheric concentrations. Therefore, it is assumed that the organism does not persist in products like pelleted feed, meals, egg powder and spices, which are often contaminated by Salmonella. A number of preventive measures on different levels, taken simultaneously, are needed to reduce the incidence of campylobacteriosis in man.

Community-acquired bacteremia among hospitalized children in rural central Africa.

OBJECTIVE: To describe the epidemiology of community-acquired bacteremia in children admitted to a rural hospital in central Africa and to identify useful diagnostic signs or symptoms. METHODS: On admission, a blood culture was obtained from all children admitted to Children's Hospital of Lwiro between 1989 and 1990. Clinical and biologic signs of infection and nutritional status were recorded. RESULTS: Among the 779 children included in the study, 15.9% were bacteremic on admission. The rate of bacteremia was the highest among children with jaundice (20/56; 35.7%) and fever (119/487; 24.4%). In contrast, children with severe malnutrition had a lower rate of bacteremia (13.2%) than weight growth retarded or well-nourished children (19.5%) (P = 0.046). Fever was the most useful diagnostic criteria (sensitivity and negative predictive value of 96.0% and 97.8%, respectively) even in severely malnourished children (sensitivity and negative predictive value of 96.4% and 99.1%, respectively). Enterobacteriacea, mostly Salmonella spp, caused 73% of the bacteremia. There was a high rate of resistance to ampicillin and chloramphenicol among the responsible organisms. Only 31 (47.7%) of 65 bacteremic children responded to the combination of ampicillin and gentamicin. The presence of bacteremia on admission did not significantly increase the risk of morality during hospitalization (19.4% compared with 13.5%; P = 0.088). Age less than 12 months and jaundice were independent risk factors for deaths in bacteremic children. CONCLUSIONS: Community-acquired bacteremia caused by multiresistant Enterobacteriacea is an important problem of hospitalized well-nourished and malnourished children in central Africa. Fever on admission is a sensitive diagnostic sign, even in malnourished children.

Contaminated enteral nutrition solutions as a cause of nosocomial bloodstream infection: a study using plasmid fingerprinting.

In July 1984, two patients fed enteral nutrition solutions contaminated with Enterobacter cloacae developed nosocomial bacteremia. Despite careful review of the preparation procedures as well as repeated microbiological surveys, 83 (27%) of the 309 formula bottles tested over a 1-yr period were contaminated and the source of contamination remained unknown. E. cloacae was the most frequent organism isolated (34%). The plasmid profiles of E. cloacae recovered from enteral nutrition solutions remained identical for several months. Blood culture isolates from 10 of the 40 patients who had developed E. cloacae nosocomial sepsis over a 7-yr period (1979-1985) had plasmid profiles linking them to contaminated enteral nutrition solutions. Epidemiological data from a case control study revealed that these 10 patients were indeed more likely to be exposed to enteral nutrition than the 30 others: 9/10 vs 10/30 (odds ratio 18, p = 0.002). Similarly, two of seven nosocomial Klebsiella pneumoniae bacteremias over a 6-month period in 1986 could be ascribed to administration of contaminated enteral liquid feeds prompting a general policy for using sterile commercially prepared solutions. Our results suggest that contaminated enteral nutrition solutions represent a significant cause of nosocomial sepsis.

Campylobacter Enteritis.

Campylobacter jejuni (previously called "related vibrio") has recently become recognized as an important cause of acute diarrhoeal disease in many countries. As with other intestinal pathogens, the clinical picture of C. jejuni infection varies from symptomless excretion to severe disease. The incubation period averages two to five days. Fever, abdominal pain and bloody diarrhoea are the usual symptoms of campylobacter enteritis. Although it is normally a self-limiting disease, complications such as cholecystitis, peritonitis, septicaemia and meningitis occasionally arise. The small intestine is thought to be the main site of infection, but the colon is also regularly involved. The disease might be more accurately described as an enterocolitis. Campylobacters, like salmonellae and yersiniae, are thought to be pathogenic by virtue of their invasive ability. Chemotherapy is usually effective. Erythromycin is commonly used for patients ill enough to require specific treatment. Although the infection can be transmitted from person to person, it is mainly a zoonosis with many possible routes of infection. Poultry is a potential source of infection, dogs may also transmit the disease and there have been major outbreaks of campylobacter enteritis from the consumption of untreated or inadequately treated milk and water. Further epidemiological work is hampered by the lack of suitable typing techniques.

Activity of doxycycline against respiratory pathogens.

149 patients were admitted from the Brussels area to the multi-centre Pan European trial of doxycycline in respiratory tract infections. Of these, 40 satisfied the strict criteria for detailed bacteriological study with positive culture of a known pathogen before treatment and bacteriological follow-up after treatment. The pathogens were beta-haemolytic streptococcus, group A (29 cases), pneumococcus (6 cases) and Haemophilus influenzae (6 cases); in one case, the pneumococcus and H. influenzae were present together. The results of doxycycline therapy were excellent, this included both its in vivo and in vitro activity; only one strain of pneumococcus proved resistant.

[Antimicrobial treatment of diarrhea of infectious origin]. / Le traitement antimicrobien de la diarrhée d'origine infectieuse.

Since dehydration is the most frequent complication of acute diarrhoea, fluid and electrolyte repletion are the most important components of treatment. In mild diarrhoea and cases where the etiologic agent is unknown there is no need for antimicrobial chemotherapy. Indeed the benefit of an antibiotic has never been proven in these cases. Moreover side effects can occur: change in gut flora causing chronic diarrhoea, selection of drug-resistant strains, pseudomembranous colitis, toxicity of the drug. Antibiotics are often useless because a large number of diarrhoeal illnesses are caused by viruses or are of nonmicrobial origin (Rotaviruses may be responsible for up to 60% of winterdiarrhoea in children). When the diagnosis is in doubt between a primary bowel infection and a septicaemic illness antibiotic therapy is of course fully justified.

Serum sensitivity of strains isolated and antibodies against O antigen in gram-negative bacteraemia.

The sensitivity of blood culture isolates to the bactericidal activity of normal human serum (NHS) has been studied in 101 patients with gram-negative sepsis. These results were compared with clinical status and outcome, and to the presence of specific IgG or IgM antibodies to O antigens of bacteraemic strains in autologous serum. 23% of the strains were markedly resistant, 27% markedly sensitive and 50% intermediately sensitive to the bactericidal activity of NHS. Shock or death occurred more frequently in immunocompromised patients and those infected with serum-resistant strains. IgG antibody titres to O antigens were significantly lower in patients with serum-resistant organisms regardless of their immune status. Resistance to natural bactericidal antibodies and low immunogenicity of the infecting organism, plus immunodeficiency in the host, may account for apparent increased virulence of some gram-negative bacilli.

Susceptibility of related vibrios and Vibrio fetus to twelve antibiotics.

One hundred fourteen strains of related vibrio and seven strains of Vibrio fetus, all isolated from humans, were tested for susceptibility in vitro to 12 antibiotics. Mueller-Hinton agar containing 14 dilutions of the antibiotics was inoculated with undiluted overnight cultures. Gentamicin and erythromycin were the most active drugs against related vibrios and Vibrio fetus; lower activity was noted with chloramphenicol, streptomycin, and tetracycline; neomycin and kanamycin were even less active. The susceptibility to ampicillin was variable. More than 90% of the strains were resistant to cephalothin.