Surveillance of giardiasis in Northwest England 1996-2006: impact of an enzyme immunoassay test.

The incidence of giardiasis in Central Lancashire increased following the introduction of a sensitive enzyme immunoassay diagnostic test in November 2002. We compared the epidemiological trends for 1996-2006 in Central Lancashire with a control area which used a standard wet preparation diagnostic method throughout. Poisson regression modelling was used to investigate trends in giardiasis before and after the introduction of the test. In the control area, incidence of giardiasis was four per 100,000 in 2005. In contrast, in Central Lancashire, the rates increased in temporal association with the introduction of the enzyme immunoassay test from 10.1 per 100,000 population in 2002 to 33.6 per 100,000 in 2006. The increase in giardiasis was unexplained by local factors including travel, outbreaks or sampling trends. The increase in giardiasis occurred in all age groups except for males aged 0-14 years and was most marked in males aged 25-44 years. The relative risk for trend post-test introduction in Central Lancashire was 1.11 (95% CI, 1.01-1.23). This suggests that the increase in giardiasis following the introduction of the sensitive enzyme immunoassay test was at least in part due to improved detection. There appears to be considerable under-diagnosis of giardiasis, particularly in adults. Additional research is required to evaluate the enzyme immunoassay test more widely. The test may assist in standardisation of diagnostic methods for giardiasis and enable more accurate estimation of disease burden and transmission routes.

Clinical definition for invasive Salmonella infection in African children.

BACKGROUND: Invasive salmonellosis is common among children in tropical Africa, typically presenting as a nonspecific febrile illness that is difficult to distinguish clinically from malaria. This study examines the performance of a clinical definition devised to aid its recognition among children ages 1 to 15 years presenting to a mission hospital in rural Zaire. METHODS: Invasive salmonellosis was defined by: (1) illness requiring admission to hospital in the opinion of an experience pediatrician; (2) history of fever for 5 or more days; (3) no focus of infection on clinical examination; and (4) negative or only scanty positive thick film for malarial parasites. Children fulfilling all these criteria were treated with ciprofloxacin after culture of blood and feces. The primary outcome measure was blood culture-confirmed salmonellosis. Secondary measures were final clinical diagnosis and serologic evidence of recent salmonellosis. RESULTS: Of 120 children fulfilling the definition, 55 (46%) were bacteremia; in 46 (38%) Salmonella species were isolated. In the majority of the nonbacteremic children no definite cause for the fever could be found. Salmonella serology supported invasive salmonellosis as the diagnosis in 62% of the nonbacteremic children. CONCLUSION: Salmonella serology suggested that invasive salmonellosis without detectable bacteremia was common. The addition of blood culture-proved and serologically diagnosed cases indicates that the definition has a specificity of at least 60%.

The serodiagnosis of infection with Salmonella typhi.

BACKGROUND/AIMS: The serodiagnosis of infection with Salmonella typhi, using the Widal agglutination assay, relies on patients' antibodies to the O = 9,12 lipopolysaccharide (LPS) antigens, H = d flagellar antigens, and the Vi capsular antigens. A Vi agglutination titre of > 1/40 has traditionally been regarded as indicative of recent infection with S typhi. In this study, 91 sera were used to assess the reliability of the Widal agglutination assay based on antibodies to the Vi antigens. METHODS: The Widal agglutination assay was carried out using protocols established by the Central Public Health Laboratory, Colindale. Antibodies to the Vi capsular antigen were detected using a standard preparation of S typhi, ViI Bhatnagar variant strain (S typhi, ViI). Sera used in the study comprised 73 from patients who were culture positive for S typhi, 10 from patients who were culture positive for other species of Salmonella not expressing a Vi antigen (namely, S javiana, S enteritidis, S typhimurium, S stanley, S saint paul, S bareilly, or S mbandaka), and eight from healthy blood donors. RESULTS: Agglutination titres of > or = 1/40 were detected to S typhi ViI in 69 of 73 sera from patients with typhoid, although 27 of these also agglutinated an unrelated control antigen. The Widal assay also detected significant amounts of agglutinating antibodies to S. typhi ViI in all eight control sera and seven sera from patients infected with S bareilly, S enteritidis, S javiana, S mbandaka, S saint paul, and S stanley. CONCLUSIONS: Agglutinating antibodies to the Vi antigen can be detected by the Widal assay, but even with the appropriate control antigens the results were unreliable. The serodiagnosis of infections with S typhi should be based on the detection of antibodies to both the O = 9,12 LPS antigen and the H = d flagellar antigen by immunoblotting, and should not use the Vi antigen-based Widal assay. Conclusions should be made in the light of patients' clinical details and any knowledge of previous immunisation for typhoid.

Serological response of patients infected with Salmonella typhi.

AIMS: To evaluate a rapid immunoblotting procedure for providing evidence of infection with Salmonella typhi using 73 sera from patients infected with S typhi. METHODS: A sodium dodecyl sulphatepolyacrylamide gel electrophoresis (SDS-PAGE)/immunoblotting procedure using lipopolysaccharide (LPS, O = 9,12) and flagellar (H = d) antigens was used. RESULTS: Seventy two of 73 sera contained antibodies to LPS, 40 sera also contained antibodies to H = d flagellar antigens. Analysis of acute and convalescent sera showed that only 62% of patients produced antibodies to flagellar antigens. CONCLUSIONS: The SDS-PAGE/immunoblotting procedure provided a rapid method for providing serological evidence of infection with S typhi.

A morphological study of bacterial colonisation of intravenous cannulae.

In an investigation of bacterial colonisation of intravascular cannulae, 16 peripheral venous cannulae of the Venflon variety and 24 chronic haemodialysis cannulae were studied after removal from patients. Studies of colonisation included semi-quantitative microbiological culture and scanning electronmicrographic (SEM) observations. The microbiological findings indicated colonisation of the intravascular portion of the catheter in 4 of 16 Venflon cannulae and 18 of 26 haemodialysis cannulae, largely with skin commensal organisms. The results of the SEM studies were in broad agreement with the microbiological observations. Surface defects on the cannulae were shown to be associated with microbial colonisation which occurred either as isolated colonies or in association with a cellular fibrinous matrix. These observations are illustrated and discussed.

Studies on the microbiological safety of the valved side-port of the 'Venflon' cannula.

A randomized prospective study was conducted to assess the effect of inserting a bacteria-retaining filter into the side-port of 'Venflon' cannulae. Observations were made on 109 cannulae with filters and 100 without. Although there was a trend towards a reduced rate of side-port colonization in the cannulae with filters this was not paralleled by any reduction in the incidence of local inflammation or colonization of the intravascular segment (IVS) of the cannula. Of the 37 cannulae with positive cultures from the skin at the cannula insertion site 22 yielded indistinguishable bacteria from the IVS, while only three of the 25 positive side-port cultures were similarly associated. It is concluded that in the majority of cases, organisms isolated from the IVS originate on the skin and that organisms introduced via the side-port rarely lead to IVS colonization.

Salmonella dublin infection of a prosthetic vascular graft successfully treated with ciprofloxacin.

The treatment of an infected vascular graft invariably requires an extra-anatomic bypass through a non-infected tissue plane, as simple drainage with antibiotics is rarely successful. We report a case in which an established infection of a prosthetic vascular graft with Salmonella dublin was successfully treated with simple drainage and a prolonged course of oral ciprofloxacin.

Metastatic pneumococcal endophthalmitis: report of two cases and review of literature.

Two patients with pneumococcal bacteraemia complicated by endophthalmitis are described. While this condition appears to have been relatively common in the preantibiotic era, a review of the literature since 1950 only identified six additional case reports. Analysis of these eight cases reveals two patterns: unilateral disease in six patients and bilateral disease with simultaneous onset in two patients. The potential pathogenic mechanisms--direct bacterial invasion or immunologically mediated processes--are discussed in relation to these clinical presentations. The critical importance of seeking ophthalmological advice early in the course of the disease is emphasised, as the risk of visual loss with systemic antimicrobials alone is very high, particularly if the infective process involves the vitreous humour.

The treatment of neonatal meningitis due to gram-negative bacilli with ciprofloxacin: evidence of satisfactory penetration into the cerebrospinal fluid.

We describe two cases of neonatal meningitis due to Gram-negative bacilli treated successfully with ciprofloxacin. Examination of serial samples of cerebrospinal fluid indicated the effect of meningeal inflammation on penetration of this drug into the CSF.

Salmonella bacteraemia among young children at a rural hospital in western Zaire.

An analysis of 206 cases of extra-intestinal Salmonella infection among children up to 60 months of age admitted to a rural hospital in western Zaire was undertaken. Most children presented with fever but without any focus of infection which was difficult to distinguish clinically from falciparum malaria. The majority (83%) of the infections were due to serotypes other than S. typhi. Infection with these serotypes was clinically indistinguishable from S. Typhi infection and was associated with a comparably high case fatality rate of 23%. Death was significantly associated with age under 6 months (relative risk 1.7), meningitis (RR 4.7), jaundice (RR 2.5), severe anaemia (RR 1.8), contracting disease in the late wet season when malnutrition peaks (RR 2.6) and infection with a chloramphenicol-resistant isolate (RR 3.2). The increasing prevalence of antibiotic resistance and HIV infection will complicate the management of this disease in the future.

PIP: Between 1982 and 1986 in western Zaire, a pediatrician collected data on 206 children under 5 years old presenting at the Institute Medical Evangelique, a 400-bed mission hospital (60 pediatric beds), in Kimpese with persisting fever despite chloroquine therapy for falciparum malaria, a negative or scanty positive thick film for malaria, and no clear localizing signs of infections. The pediatrician suspected that these cases had an extraintestinal Salmonella infection and took blood, synovial fluid, and/or cerebrospinal fluid samples for diagnostic analyses. Salmonella serotypes other than Salmonella typhi (non-S. typhi) were responsible for most bacteremia cases (83%). The clinical features of non-S. typhi and S. typhi infections were basically the same. The case fatality rate for non-S. typhi and S. typhi an S. typhi infections were 22.7% and 29.4%, respectively. Infants under 6 months old had a significantly higher case fatality rate than older children (relative risk [RR] = 1.7; p .0005; e.g., 66% and 100% for infants under 3 months old). Meningitis was significantly associated with increased mortality, regardless of age (RR = 4.68). Jaundice was the only clinical sign significantly linked to increased mortality (RR = 2.35), especially among children who had S. typhi infection (80%). Mortality occurred significantly more often when children fell ill with Salmonella bacteremia in the late rainy season, coinciding with the peak of malnutrition, than in the dry season (RR = 2.62). Chloramphenicol-resistant non-S. typhi isolated were significantly associated with increased mortality (RR = 3.19). Hemoglobin levels below 6 g (i.e. severe anemia) has a strong link to increased mortality (RR = 1.77). Salmonella bacteremia will become more difficult to treat as antibiotic resistance and the prevalence of HIV infection increases in African countries.

A case of herpes zoster associated encephalitis with rapid response to acyclovir.

A case of herpes zoster encephalitis which responded very rapidly to acyclovir is presented. The differential serum: cerebrospinal fluid antibody response was followed and its value in making the diagnosis is discussed. The penetration of acyclovir into the cerebrospinal fluid was measured, and found to be in agreement with predicted values.

The management of splenic abscess.

We report three patients with splenic abscess whom we attempted to treat without recourse to open surgery. Medical treatment alone was successful in one case, and medical treatment combined with percutaneous drainage was successful in the second. Splenectomy was required in the third case after failure of medical treatment and complications of percutaneous drainage. The difficulties in diagnosing splenic abscess are reviewed and the indications for splenectomy or percutaneous drainage, as opposed to medical treatment are considered.

A prospective study of the mechanisms of infection associated with hemodialysis catheters.

Seventy-four subclavian hemodialysis catheters inserted into 53 patients were studied prospectively. Sixteen of 64 assessable catheterization periods were complicated by clinically documented catheter-related sepsis, and 13 had an associated bacteremia. One patient died from catheter-related sepsis, and in two others, sepsis contributed to death. Staphylococci accounted for 11 bacteremias. Semiquantitative culture of the catheters indicated that 28 were significantly colonized. Comparison of these isolates with skin cultures from the insertion site suggested that the origin of the colonizing organisms was the skin (10 cases), intralumenal contamination (16 cases), or both routes (2 cases). Comparison of cultures taken during catheter insertion with those at removal rarely suggested that organisms introduced at insertion caused subsequent colonization. This study has demonstrated that infectious complications from using subclavian hemodialysis catheters exceed reported rates for all other modes of vascular access used for hemodialysis, as well as other indications for central venous catheterization.

Meningococcal meningitis and carriage in western Zaire: a hypoendemic zone related to climate?

An analysis of bacteria recovered from cerebrospinal fluid over a 16-year period at a rural hospital in western Zaire showed that Neisseria meningitidis accounted for only five (2.2%) isolates. A survey of naso-pharyngeal colonisation with N. meningitidis in 378 healthy children was undertaken to distinguish whether this low frequency was due to lack of carriage or, by inference, lack of the co-factors necessary to permit invasive disease. N. meningitidis was recovered from only three (0.78%) of the children. All isolates were non-typable strains of low pathogenicity. A review of studies examining the aetiology of bacterial meningitis and the geographical location of epidemics of meningococcal meningitis in and around Zaire reveals a 'hypoendemic zone', the limits of which correlate well with the area in which mean absolute humidity remains above 10 g m-3 of air throughout the year. Continuous high absolute humidity appears to reduce the transmission of meningococci.

The complications of intravenous cannulae incorporating a valved injection side port.

In a series of 519 intravenous cannulae with valved injection side-ports the incidence of cannula-related local inflammation was 25.2% and bacteraemia 0.2%. Severe local inflammation was associated with a longer mean duration of cannulation, 59.4 v. 81.4 h (P = less than 0.05). There was no significant association between the presence of local inflammation and microbial colonization of either the intravascular segment of the cannula, the adjacent skin, or the side-port. The data suggest that colonization of the cannulae was usually secondary to prior skin colonization. Side-port colonization did not predispose to cannula colonization. Organisms colonizing the side-port were biologically different and were possibly derived from the skin of medical attendants. In the final 157 patients, randomized to receive either isopropyl alcohol or 0.5% chlorhexidine in 70% spirit skin preparation, there was no difference in the incidence of either local inflammation or microbial colonization.