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

Large outbreak of typhoid fever on a river cruise ship used as accommodation for asylum seekers, the Netherlands, 2022

On 6 April 2022, the Public Health Service of Kennemerland, the Netherlands, was notified about an outbreak of fever and abdominal complaints on a retired river cruise ship, used as shelter for asylum seekers. The diagnosis typhoid fever was confirmed on 7 April. An extensive outbreak investigation was performed. Within 47 days, 72 typhoid fever cases were identified among asylum seekers (n = 52) and staff (n = 20), of which 25 were hospitalised. All recovered after treatment. Consumption of food and tap water on the ship was associated with developing typhoid fever. The freshwater and wastewater tanks shared a common wall with severe corrosion and perforations, enabling wastewater to leak into the freshwater tank at high filling levels. Salmonella Typhi was cultured from the wastewater tank, matching the patient isolates. In the freshwater tank, Salmonella species DNA was detected by PCR, suggesting the presence of the bacterium and supporting the conclusion of contaminated freshwater as the probable source of the outbreak. Outbreaks of uncommon infections may occur if persons from endemic countries are accommodated in crowded conditions. Especially when accommodating migrants on ships, strict supervision on water quality and technical installations are indispensable to guarantee the health and safety of the residents.

Complications and mortality of non-typhoidal salmonella invasive disease: a global systematic review and meta-analysis

BACKGROUND

Non-typhoidal salmonella can cause serious, life-threatening invasive infections involving the bloodstream and other normally sterile sites. We aimed to systematically review the prevalence of complications and case-fatality ratio (CFR) of non-typhoidal salmonella invasive disease to provide contemporary global estimates and inform the development of vaccine and non-vaccine interventions.

METHODS

We did a global systematic review and meta-analysis of studies investigating the complications and mortality associated with non-typhoidal salmonella invasive disease. We searched Embase, MEDLINE, Web of Science, and PubMed for peer-reviewed, primary research articles published from database inception up to June 4, 2021, with no restrictions on language, country, date, or participant demographics. Only studies reporting the proportion of complications or deaths associated with non-typhoidal salmonella invasive disease, confirmed by culture of samples taken from a normally sterile site (eg, blood or bone marrow) were included. We excluded case reports, case series, policy reports, commentaries, editorials, and conference abstracts. Data on the prevalence of complications and CFR were abstracted. The primary outcomes were to estimate the prevalence of complications and CFR of non-typhoidal salmonella invasive disease. We calculated an overall pooled CFR estimate and pooled CFR stratified by UN region, subregion, age group, and by serovar when available with a random-effects meta-analysis. A risk-of-bias assessment was done, and heterogeneity was assessed with Cochran's Q Test, I2, and τ2. This study was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, and is registered with PROSPERO, CRD42020202293.

FINDINGS

The systematic review returned a total of 8770 records. After duplicates were removed, 5837 titles and abstracts were screened, yielding 84 studies from 35 countries after exclusions. Of these included studies, 77 (91·7%) were hospital-based and 66 (78·6%) were located in Africa or Asia. Among 55 studies reporting non-typhoidal salmonella disease-associated complications, a total of 45 different complications were reported and 1824 complication events were identified among 6974 study participants. The most prevalent complication was septicaemia, occurring in 171 (57·2%) of 299 participants, followed by anaemia in 580 (47·3%) of 1225 participants. From 81 studies reporting the CFR of non-typhoidal salmonella invasive disease, the overall pooled CFR estimate was 14·7% (95% CI 12·2-17·3). When stratified by UN region, the pooled CFR was 17·1% (13·6-21·0) in Africa, 14·0% (9·4-19·4) in Asia, 9·9% (6·4-14·0) in Europe, and 9·6% (0·0-25·1) in the Americas. Of all 84 studies, 66 (78·6%) had an overall high risk of bias, 18 (21·4%) had a moderate risk, and none had a low risk. Substantial heterogeneity (I2>80%) was observed in most (15 [65·2%] of 23) CFR estimates.

INTERPRETATION

Complications were frequent among individuals with non-typhoidal salmonella invasive disease and approximately 15% of patients died. Clinicians, especially in African countries, should be aware of non-typhoidal salmonella invasive disease as a cause of severe febrile illness. Prompt diagnoses and management decisions, including empiric antimicrobial therapy, would improve patient outcomes. Additionally, investments in improving clinical microbiology facilities to identify non-typhoidal salmonella and research efforts towards vaccine development and non-vaccine prevention measures would prevent non-typhoidal salmonella invasive disease-associated illness and death.

FUNDING

EU Horizon 2020 research and innovation programme.

Contribution of Governance and Socioeconomic Factors to the P. aeruginosa MDR in Europe

This work aims to explain the behavior of the multi-drug resistance (MDR) percentage of Pseudomonas aeruginosa in Europe, through multivariate statistical analysis and machine learning validation, using data from the European Antimicrobial Resistance Surveillance System, the World Health Organization, and the World Bank. We ran a multidimensional data panel regression analysis and used machine learning techniques to validate a pooling panel data case. The results of our analysis showed that the most important variables explaining the MDR phenomena across European countries are governance variables, such as corruption control and the rule of law. The models proposed in this study showed the complexity of the antibiotic drugs resistance problem. The efforts controlling MDR P. aeruginosa, as a well-known Healthcare-Associated Infection (HCAI), should be focused on solving national governance problems that impact resource distribution, in addition to individual guidelines, such as promoting the appropriate use of antibiotics.

Complete Genome Sequences of African Salmonella enterica Serovar Enteritidis Clinical Isolates Associated with Bloodstream Infection

We report the complete genome sequencing and annotation of four Salmonella enterica serovar Enteritidis isolates, two that are representative of the Central/Eastern African clade (CP255 and D7795) and two of the Global Epidemic clade (A1636 and P125109).

Complications and mortality of typhoid fever: A global systematic review and meta-analysis

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Complications and death are considerable among hospitalized patients with typhoid fever.

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Case fatality ratio of typhoid fever was higher in Africa compared to Asia.

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Among studies in Africa, 20% of patients with typhoid intestinal perforation died.

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Delays in care were correlated with increased typhoid case fatality ratio in Asia.

Objectives

Updated estimates of the prevalence of complications and case fatality ratio (CFR) among typhoid fever patients are needed to understand disease burden.

Methods

Articles published in PubMed and Web of Science from 1 January 1980 through 29 January 2020 were systematically reviewed for hospital or community-based non-surgical studies that used cultures of normally sterile sites, and hospital surgical studies of typhoid intestinal perforation (TIP) with intra- or post-operative findings suggestive of typhoid. Prevalence of 21 pre-selected recognized complications of typhoid fever, crude and median (interquartile range) CFR, and pooled CFR estimates using a random effects meta-analysis were calculated.

Results

Of 113 study sites, 106 (93.8%) were located in Asia and Africa, and 84 (74.3%) were non-surgical. Among non-surgical studies, 70 (83.3%) were hospital-based. Of 10,355 confirmed typhoid patients, 2,719 (26.3%) had complications. The pooled CFR estimate among non-surgical patients was 0.9% for the Asia region and 5.4% for the Africa region. Delay in care was significantly correlated with increased CFR in Asia (r = 0.84; p<0.01). Among surgical studies, the median CFR of TIP was 15.5% (6.7–24.1%) per study.

Conclusions

Our findings identify considerable typhoid-associated illness and death that could be averted with prevention measures, including typhoid conjugate vaccine introduction.

Current status of resistance to antibiotics in the Democratic Republic of the Congo: A review

A review of literature was conducted to assess the prevalence and mechanisms of antibiotic resistance to date, mainly to β-lactam antibiotics, cephalosporins, carbapenems, colistin, and tigecycline in the Democratic Republic of the Congo (DRC). English and French publications were listed and analysed using PubMed/Medline, Google Scholar, and African Journals database between 1 January 1990 and 31 December 2019. For the 30 published articles found: (1) bacterial resistance to antibiotics concerned both Gram-negative and Gram-positive bacteria; (2) multidrug resistance prevalence was the same in half of Streptococcus pneumoniae isolates; (3) a worrying prevalence of methicillin-resistant Staphylococcus aureus (MRSA) was noted, which is associated with co-resistance to several other antibiotics; and (4) resistance to third-generation cephalosporins was very high in Enterobacteriaceae, mainly because of bla_CTX-M-1 group and bla_SHV genes. Data on carbapenem and colistin resistance were not available in DRC until recently. Further work is required to set up a surveillance system for antibiotic resistance in DRC.

Non-typhoidal Salmonella intestinal carriage in a Schistosoma mansoni endemic community in a rural area of the Democratic Republic of Congo

BACKGROUND

Clinical observations and animal studies have suggested that Salmonella intestinal carriage is promoted by concurrent Schistosoma infection. The present study assessed association of Salmonella intestinal carriage and Schistosoma mansoni infection among individuals in a Schistosoma endemic area in sub-Saharan Africa.

METHODS

From November 2015 to March 2016, a cross-sectional community-wide study was conducted in Kifua II, a rural village in Kongo Central Province, Democratic Republic of Congo. Stool samples were collected and analyzed for Salmonella intestinal carriage (culture) and Schistosoma mansoni infection (Kato Katz microscopy with determination of egg load). Salmonella Typhimurium and Enteritidis isolates were assessed for genetic similarity with blood culture isolates obtained during the same period in a neighboring hospital using multi-locus variable-numbers tandem repeat analysis (MLVA).

RESULTS

A total of 1,108 participants were included (median age 15 years (IQR: 7-36), male-to-female ratio of 1:1.1). The overall prevalence of Schistosoma mansoni infection and non-typhoidal Salmonella carriage was 51.2% (95% CI: 48.2-54.1) and 3.4% (95% CI: 2.5-4.7) respectively, with 2.2% (95% CI: 1.5-3.2) of participants coinfected. The proportion of Salmonella carriage tended to be higher among Schistosoma mansoni infected participants compared to non-infected participants but this difference did not reach statistical significance (4.2% versus 2.6%, p = 0.132). However, the proportion of Salmonella carriage among participants with a heavy Schistosoma mansoni infection was significantly higher compared to those with a light and moderate infection (8.7% versus 3.2%, p = 0.012) and compared to Schistosoma mansoni negatives (8.7% versus 2.6%, p = 0.002). The 38 Salmonella isolates comprised five and four Enteritidis and Typhimurium serotypes respectively, the majority of them had MLVA types identical or similar to those observed among blood culture isolates.

CONCLUSION

Salmonella intestinal carriage was associated with a heavy intensity of Schistosoma mansoni infection. Further studies are needed to address causation.

A Systematic Review of the Incidence, Risk Factors and Case Fatality Rates of Invasive Nontyphoidal Salmonella (iNTS) Disease in Africa (1966 to 2014)

This study systematically reviews the literature on the occurrence, incidence and case fatality rate (CFR) of invasive nontyphoidal Salmonella (iNTS) disease in Africa from 1966 to 2014. Data on the burden of iNTS disease in Africa are sparse and generally have not been aggregated, making it difficult to describe the epidemiology that is needed to inform the development and implementation of effective prevention and control policies. This study involved a comprehensive search of PubMed and Embase databases. It documents the geographical spread of iNTS disease over time in Africa, and describes its reported incidence, risk factors and CFR. We found that Nontyphoidal Salmonella (NTS) have been reported as a cause of bacteraemia in 33 out of 54 African countries, spanning the five geographical regions of Africa, and especially in sub-Saharan Africa since 1966. Our review indicates that NTS have been responsible for up to 39% of community acquired blood stream infections in sub-Saharan Africa with an average CFR of 19%. Salmonella Typhimurium and Enteritidis are the major serovars implicated and together have been responsible for 91%% of the cases of iNTS disease, (where serotype was determined), reported in Africa. The study confirms that iNTS disease is more prevalent amongst Human Immunodeficiency Virus (HIV)-infected individuals, infants, and young children with malaria, anaemia and malnutrition. In conclusion, iNTS disease is a substantial cause of community-acquired bacteraemia in Africa. Given the high morbidity and mortality of iNTS disease in Africa, it is important to develop effective prevention and control strategies including vaccination.

Surveillance of invasive infection in children and adults admitted to QECH, Blantyre, 1996-2002

This is a report of blood CSF isolates from the adults medical and paediatric of wards QECH, Blantyre, cultured and identified at the Welcome Trust Research Laboratories during 1996-2002. The commonest causes of adults and children bacteraemia were non-typhoidal Salmonella (35% of all blood isolates for adults and children) and Streptococcus pneumoniae (14% and 13% respectively). Cryptococcus neoformans was the commonest isolates from CSF of adults with meningitis(67%) but was very rare in children. S.pneumoniae was the commonest cause of bacterial meningitis in children and adults (38% and 28% of all CSF isolates respectively). Haemophilus influenzae type b was also a common cause of meningitis in children (27%). Data of in vitro antibiotic sensitivity are also reported. A major concern is the recent marked rise of chloramphenicol resistance among Salmonella enteritidis and Salmonella typhimurium to over 80% resistance.

Epidemiology and Genomics of Invasive Nontyphoidal Salmonella Infections in Kenya

BACKGROUND

In Kenya, invasive nontyphoidal Salmonella (iNTS) disease causes severe bacteremic illness among adults with human immunodeficiency virus (HIV) and especially among children <5 years of age coinfected with HIV or malaria, or who are compromised by sickle cell disease or severe malnutrition. The incidence of iNTS disease in children ranges from 166 to 568 cases per 100,000 persons per year.

METHODS

We review the epidemiology of iNTS disease and genomics of strains causing invasive illness in Kenya. We analyzed a total of 192 NTS isolates (114 Typhimurium, 78 Enteritidis) from blood and stools from pediatric admissions in 2005-2013. Testing for antimicrobial susceptibility to commonly used drugs and whole-genome sequencing were performed to assess prevalence and genetic relatedness of multidrug-resistant iNTS strains, respectively.

RESULTS

A majority (88/114 [77%]) of Salmonella Typhimurium and 30% (24/79) of Salmonella Enteritidis isolates tested were found to be multidrug resistant, whereas a dominant Salmonella Typhimurium pathotype, ST313, was primarily associated with invasive disease and febrile illness. Analysis of the ST313 isolates has identified genome degradation, compared with the ST19 genotype that typically causes diarrhea in humans, especially in industrialized countries, adapting a more host-restricted lifestyle typical of Salmonella Typhi infections.

CONCLUSIONS

From 2012, we have observed an emergence of ceftriaxone-resistant strains also showing reduced susceptibility to fluoroquinolones. As most cases present with nonspecific febrile illness with no laboratory-confirmed etiology, empiric treatment of iNTS disease is a major challenge in Kenya. Multidrug resistance, including to ceftriaxone, will pose further difficulty in management of iNTS disease in endemic areas.

Epidemiology, Clinical Presentation, Laboratory Diagnosis, Antimicrobial Resistance, and Antimicrobial Management of Invasive Salmonella Infections

Salmonella enterica infections are common causes of bloodstream infection in low-resource areas, where they may be difficult to distinguish from other febrile illnesses and may be associated with a high case fatality ratio. Microbiologic culture of blood or bone marrow remains the mainstay of laboratory diagnosis. Antimicrobial resistance has emerged in Salmonella enterica, initially to the traditional first-line drugs chloramphenicol, ampicillin, and trimethoprim-sulfamethoxazole. Decreased fluoroquinolone susceptibility and then fluoroquinolone resistance have developed in association with chromosomal mutations in the quinolone resistance-determining region of genes encoding DNA gyrase and topoisomerase IV and also by plasmid-mediated resistance mechanisms. Resistance to extended-spectrum cephalosporins has occurred more often in nontyphoidal than in typhoidal Salmonella strains. Azithromycin is effective for the management of uncomplicated typhoid fever and may serve as an alternative oral drug in areas where fluoroquinolone resistance is common. In 2013, CLSI lowered the ciprofloxacin susceptibility breakpoints to account for accumulating clinical, microbiologic, and pharmacokinetic-pharmacodynamic data suggesting that revision was needed for contemporary invasive Salmonella infections. Newly established CLSI guidelines for azithromycin and Salmonella enterica serovar Typhi were published in CLSI document M100 in 2015.

Invasive Salmonella infections in areas of high and low malaria transmission intensity in Tanzania

BACKGROUND

 The epidemiology of Salmonella Typhi and invasive nontyphoidal Salmonella (NTS) differs, and prevalence of these pathogens among children in sub-Saharan Africa may vary in relation to malaria transmission intensity.

METHODS

 We compared the prevalence of bacteremia among febrile pediatric inpatients aged 2 months to 13 years recruited at sites of high and low malaria endemicity in Tanzania. Enrollment at Teule Hospital, the high malaria transmission site, was from June 2006 through May 2007, and at Kilimanjaro Christian Medical Centre (KCMC), the low malaria transmission site, from September 2007 through August 2008. Automated blood culture, malaria microscopy with Giemsa-stained blood films, and human immunodeficiency virus testing were performed.

RESULTS

 At Teule, 3639 children were enrolled compared to 467 at KCMC. Smear-positive malaria was detected in 2195 of 3639 (60.3%) children at Teule and 11 of 460 (2.4%) at KCMC (P < .001). Bacteremia was present in 336 of 3639 (9.2%) children at Teule and 20 of 463 (4.3%) at KCMC (P < .001). NTS was isolated in 162 of 3639 (4.5%) children at Teule and 1 of 463 (0.2%) at KCMC (P < .001). Salmonella Typhi was isolated from 11 (0.3%) children at Teule and 6 (1.3%) at KCMC (P = .008). With NTS excluded, the prevalence of bacteremia at Teule was 5.0% and at KCMC 4.1% (P = .391).

CONCLUSIONS

 Where malaria transmission was intense, invasive NTS was common and Salmonella Typhi was uncommon, whereas the inverse was observed at a low malaria transmission site. The relationship between these pathogens, the environment, and the host is a compelling area for further research.

Genomic characterisation of invasive non-typhoidal Salmonella enterica Subspecies enterica Serovar Bovismorbificans isolates from Malawi

Background

Invasive Non-typhoidal Salmonella (iNTS) are an important cause of bacteraemia in children and HIV-infected adults in sub-Saharan Africa. Previous research has shown that iNTS strains exhibit a pattern of gene loss that resembles that of host adapted serovars such as Salmonella Typhi and Paratyphi A. Salmonella enterica serovar Bovismorbificans was a common serovar in Malawi between 1997 and 2004.

Methodology

We sequenced the genomes of 14 Malawian bacteraemia and four veterinary isolates from the UK, to identify genomic variations and signs of host adaptation in the Malawian strains.

Principal Findings

Whole genome phylogeny of invasive and veterinary S. Bovismorbificans isolates showed that the isolates are highly related, belonging to the most common international S. Bovismorbificans Sequence Type, ST142, in contrast to the findings for S. Typhimurium, where a distinct Sequence Type, ST313, is associated with invasive disease in sub-Saharan Africa. Although genome degradation through pseudogene formation was observed in ST142 isolates, there were no clear overlaps with the patterns of gene loss seen in iNTS ST313 isolates previously described from Malawi, and no clear distinction between S. Bovismorbificans isolates from Malawi and the UK.

The only defining differences between S. Bovismorbificans bacteraemia and veterinary isolates were prophage-related regions and the carriage of a S. Bovismorbificans virulence plasmid (pVIRBov).

Conclusions

iNTS S. Bovismorbificans isolates, unlike iNTS S. Typhiumrium isolates, are only distinguished from those circulating elsewhere by differences in the mobile genome. It is likely that these strains have entered a susceptible population and are able to take advantage of this niche. There are tentative signs of convergent evolution to a more human adapted iNTS variant. Considering its importance in causing disease in this region, S. Bovismorbificans may be at the beginning of this process, providing a reference against which to compare changes that may become fixed in future lineages in sub-Saharan Africa.

Bacteraemia and meningitis caused by non-typhoidal Salmonella (including serovars Typhimurium, Enteritidis and Bovismorbificans) are a serious health issue in sub-Saharan Africa, particularly in young children and HIV-infected adults. Previous work has indicated that a distinct S. Typhimurium sequence type, ST313, has evolved and spread in these countries, and may be more human-adapted than isolates found in the developed world. We therefore investigated the genomes of Salmonella enterica serovar Bovismorbificans bacteraemia isolates from Malawi and compared them to genomes of veterinary S. Bovismorbificans isolates from the UK using Next Generation Sequencing Technology and subsequent genomic comparisons to establish if there is a genetic basis for this increase in invasive disease observed among African NTS. Contrary to the previous findings for S. Typhimurium, where a distinct ST is found only in sub-Saharan Africa, we discovered that the S. Bovismorbificans isolates from Malawi belong to the most common ST of the serovar and the genome is highly conserved across all sequenced isolates. The major differences between UK veterinary and African human isolates were due to prophage regions inserted into the genomes of African isolates, coupled with a higher prevalence of a virulence plasmid compared to the UK isolates.

Prevalence and characterization of Salmonella enterica from the feces of cattle, poultry, swine and hedgehogs in Burkina Faso and their comparison to human Salmonella isolates

BACKGROUND

Production and wild animals are major sources of human salmonellosis and animals raised for food also play an important role in transmission of antimicrobial resistant Salmonella strains to humans. Furthermore, in sub-Saharan Africa non-typhoidal Salmonella serotypes are common bloodstream isolates in febrile patients. Yet, little is known about the environmental reservoirs and predominant modes of transmission of these pathogens. The purpose of this study was to discover potential sources and distribution vehicles of Salmonella by isolating strains from apparently healthy slaughtered food animals and wild hedgehogs and by determining the genetic relatedness between the strains and human isolates. For this purpose, 729 feces samples from apparently healthy slaughtered cattle (n = 304), poultry (n = 350), swine (n = 50) and hedgehogs (n = 25) were examined for the presence of Salmonella enterica in Burkina Faso. The isolates were characterized by serotyping, antimicrobial-susceptibility testing, phage typing, and pulsed-field gel electrophoresis (PFGE) with XbaI and BlnI restriction enzymes.

RESULTS

Of the 729 feces samples, 383 (53%) contained Salmonella, representing a total of 81 different serotypes. Salmonella was present in 52% of the cattle, 55% of the poultry, 16% of the swine and 96% of the hedgehog feces samples. Antimicrobial resistance was detected in 14% of the isolates. S. Typhimurium isolates from poultry and humans (obtained from a previous study) were multiresistant to the same antimicrobials (ampicillin, chloramphenicol, streptomycin, sulfonamides and trimethoprim), had the same phage type DT 56 and were closely related in PFGE. S. Muenster isolates from hedgehogs had similar PFGE patterns as the domestic animals.

CONCLUSIONS

Based on our results it seems that production and wild animals can share the same Salmonella serotypes and potentially transmit some of them to humans. As the humans and animals often live in close vicinity in Africa and the hygiene control of the meat retail chain is defective, high Salmonella carriage rates of the animals can pose a major public health risk in Burkina Faso. This underlines the necessity for a joint and coordinated surveillance and monitoring programs for salmonellosis in Africa.

Epidemic increase in Salmonella bloodstream infection in children, Bwamanda, the Democratic Republic of Congo

Salmonella enterica is the leading cause of bloodstream infection in children in sub-Saharan Africa, but few data are available from Central-Africa. We documented during the period November 2011 to May 2012 an epidemic increase in invasive Salmonella bloodstream infections in HGR Bwamanda, a referral hospital in Equateur Province, DR Congo. Salmonella spp. represented 90.4 % (103 out of 114) of clinically significant blood culture isolates and comprised Salmonella Typhimurium (54.4 %, 56 out of 103), Salmonella Enteritidis (28.2 %, 29 out of 103) and Salmonella Typhi (17.5 %, 18 out of 103), with Salmonella Enteritidis accounting for most of the increase. Most (82 out of 103, 79.6 %) isolates were obtained from children < 5 years old. Median ages of patients infected with Salmonella Typhimurium and Salmonella Enteritidis were 14 months (14 days to 64 years) and 19 months (3 months to 8 years) respectively. Clinical presentation was non-specific; the in-hospital case fatality rate was 11.1 %. More than two thirds (69.7 %, 53 out of 76) of children < 5 years for whom laboratory data were available had Plasmodium falciparum infection. Most (83/85, 97.6 %) non-typhoid Salmonella isolates as well as 6/18 (33.3 %) Salmonella Typhi isolates were multidrug resistant (i.e. resistant to the first-line oral antibiotics amoxicillin, trimethoprim-sulfamethoxazole and chloramphenicol), one (1.0 %) Salmonella Typhimurium had decreased ciprofloxacin susceptibility owing to a point mutation in the gyrA gene (Gly81Cys). Multilocus variable-number tandem-repeat (MLVA) analysis of the Salmonella Enteritidis isolates revealed closely related patterns comprising three major and four minor profiles, with differences limited to one out of five loci. These data show an epidemic increase in clonally related multidrug-resistant Salmonella bloodstream infection in children in DR Congo.

Bacteremia and resistant gram-negative pathogens among under-fives in Tanzania

BACKGROUND

Antibiotic resistance is one of the most serious public health concerns worldwide and is increasing at an alarming rate, making daily treatment decisions more challenging. This study is aimed at identifying local bacterial isolates and their antimicrobial susceptibility patterns to avoid irrational antibiotic use, especially in settings where unguided management occurs and febrile illnesses are predominant.

MATERIAL AND METHODS

A hospital-based prospective cross-sectional study was conducted from September 2011 to February 2012. Febrile children were serially recruited and demographic and clinical data were collected using a standardized data collection tool. A blood culture was performed and identification of the isolates was undertaken using in-house biochemical tests. Susceptibility to common antibiotics was investigated using the disc diffusion methods.

RESULTS

Of the 1081 children admitted during the study period, 317 (29.3%) met the inclusion criteria and were recruited, of whom 195 (61.5%) and 122 (38.5%) were male and female respectively. The median age was 18 months with an interquartile range of 9 to 36 months. Of the 317 children, 251 (79.2%) were below or equal to 36 months of age. The prevalence of bacteremia was 6.6%. A higher prevalence of bacteraemia was observed in children below 36 months than in those ≥ 36 months (7.5% vs. 3.0%, p = 0.001). Predictors of bacteraemia were an axillary temperature of >38.5 °C (OR =7, 95% CI = 2.2 - 14.8, p-value = 0.0001), a positive malaria slide (OR =5, 95% CI = 3.0 - 21.2, p-value = 0.0001) and a high neutrophils' count (OR =21 95% CI = 5.6 - 84, p-value = 0.0001). Escherichia coli and Klebsiella pneumoniae accounted for 7 (33.3%) and 6 (28.6%) of all the isolates respectively. Others gram-negatives bacteria were Citrobacter spp 2 (9.5%), Enterobacter spp 1 (4.25%), Pseudomonas spp 2 (9.5%), Proteus spp 1 (4.25%) and Salmonella spp 1 (4.25%). These isolates were highly resistant to ampicillin (95%), co-trimoxazole (90%), tetracycline (90%), gentamicin (80%), augmentin (80%), chloramphenicol (65%), ceftriaxone (35%), cefotaxime (35%) ciprofloxacin (30%), amikacin (30%), ceftazidime (25%) and norfloxacine (10%).

CONCLUSION

Multi-resistant gram-negative bacteria are the commonest cause of bacteremia in under-fives attending the Bugando Medical Centre, Mwanza, Tanzania. A high body temperature, a positive malaria slide and a high absolute neutrophils' count were all independent risk factors found to predict bacteremia. A higher mortality rate was observed in children with bacteraemia. Continuous epidemiological surveillance should be conducted so that a proper and effective antibiotics management can be instituted, especially in children with a high grade fever, a positive malaria slide and a high neutrophils' count.

Antimicrobial resistance in invasive non-typhoid Salmonella from the Democratic Republic of the Congo: emergence of decreased fluoroquinolone susceptibility and extended-spectrum beta lactamases

Background

Co-resistance against the first-line antibiotics ampicillin, chloramphenicol and trimethoprim/sulphamethoxazole or multidrug resistance (MDR) is common in non typhoid Salmonella (NTS). Use of alternative antibiotics, such as fluoroquinolones or third generation cephalosporins is threatened by increasing resistance, but remains poorly documented in Central-Africa.

Methodology/Principal findings

As part of a microbiological surveillance study in DR Congo, blood cultures were collected between 2007 and 2011. Isolated NTS were assessed for serotype and antimicrobial resistance including decreased ciprofloxacin susceptibility and extended-spectrum beta-lactamase (ESBL) production. In total, 233 NTS isolates (representing 23.6% of clinically significant organisms) were collected, mainly consisting of Salmonella Typhimurium (79%) and Salmonella Enteritidis (18%). The majority of NTS were isolated in the rainy season, and recovered from children ≤2 years old. MDR, decreased ciprofloxacin susceptibility, azithromycin and cefotaxime resistance were 80.7%, 4.3%, 3.0% and 2.1% respectively. ESBL production was noted in three (1.3%) isolates. Decreased ciprofloxacin susceptibility was associated with mutations in codon 87 of the gyrA gene, while ESBLs all belonged to the SHV-2a type.

Conclusions/Significance

Presence of almost full MDR among NTS isolates from blood cultures in Central Africa was confirmed. Resistance to fluoroquinolones, azithromycin and third generation cephalosporins is still low, but emerging. Increased microbiological surveillance in DR Congo is crucial for adapted antibiotic therapy and the development of treatment guidelines.

Invasive non typhoid Salmonella spp. (NTS) are an important cause of bloodstream infection in sub-Saharan Africa and associated with a high mortality. Levels of multidrug resistance have become alarmingly high. Treatment therefore increasingly relies on the oral fluoroquinolones such as ciprofloxacin, with third generation cephalosporins such as cefotaxime as alternatives for parenteral treatment. Azithromycin represents another alternative antimicrobial drug. Worldwide, increased use of these drugs is associated with spread of resistance as well, a phenomenon poorly documented in Central-Africa. In the present study, 233 NTS isolates were collected from blood cultures sampled between 2007 and 2011 in DR Congo, mainly from children ≤2 years of age. Most isolates were recovered during the rainy season. Widespread multidrug resistance was confirmed as well as decreased susceptibility to ciprofloxacin, resistance to azithromycin and resistance to third generation cephalosporins. Our findings demonstrate emergence of antibiotic resistance among NTS in DR Congo and underline the need for increased microbiological surveillance, being a prerequisite for rational antibiotic therapy and the development of standard treatment guidelines.

Susceptibility of bacterial etiological agents to commonly-used antimicrobial agents in children with sepsis at the Tamale Teaching Hospital

BACKGROUND

Bloodstream infections in neonates and infants are life-threatening emergencies. Identification of the common bacteria causing such infections and their susceptibility patterns will provide necessary information for timely intervention. This study is aimed at determining the susceptibilities of bacterial etiological agents to commonly-used antimicrobial agents for empirical treatment of suspected bacterial septicaemia in children.

METHODS

This is a hospital based retrospective analysis of blood cultures from infants to children up to 14 years of age with preliminary diagnosis of sepsis and admitted to the Neonatal Intensive Care Unit (NICU) and Paediatric Wards of the Teaching Hospital Tamale from July 2011 to January 2012.

RESULTS

Out of 331 blood specimens cultured, the prevalence of confirmed bacterial sepsis was 25.9% (86/331). Point prevalence for confirmed cases from NICU was 44.4% (28/63) and 21.6% (58/268) from the Paediatric ward. Gram positive cocci (GPC) were the predominant isolates with Coagulase positive (32.2%) and Coagulase-negative (28.7%) Staphylococci accounting for 60.9% of the total isolates. Gram negative rods (GNR) comprised 39.1% of all isolates with Klebsiella, E.coli and Salmonella being the most common organisms isolated. Klebsiella was the most frequent GNR from the NICU and Salmonella typhi was predominantly isolated from the paediatric ward. Acinetobacter showed 100.0% susceptibility to Ceftriaxone and Cefotaxime but was resistant (100.0%) to Ampicillin, Tetracycline and Cotrimoxazole. Escherichia coli and Klebsiella were 80.0% and 91.0% susceptible to Ceftriaxone and Cefotaxime respectively. Klebsiella species showed 8.3% susceptibility to Tetracycline but was resistant to Ampicillin and Cotrimoxazole. Escherichia coli showed 40.0% susceptibility to Ampicillin, Chloramphenicol and Cotrimoxazole; 20.0% susceptibility to Tetracycline and 80.0% susceptible to Gentamicin and Cefuroxime. Coagulase negative Staphylococci was susceptible to Gentamicin (72.0%) but Coagulase positive Staphylococci showed intermediate sensitivity to Gentamicin (42.9%).

CONCLUSION

Coagulase Negative, Coagulase Positive Staphylococci, Salmonella and Klebsiella were the aetiological agents of bloodstream infection among children at TTH. While gram-positive and gram-negative bacteria showed low susceptibility to Ampicillin, Tetracycline and Cotrimoxazole, the GNR were susceptible to Gentamicin and third-generation cephalosporins.

Invasive salmonellosis in urban Thai children: a ten-year review

BACKGROUND

Invasive, extraintestinal salmonellosis carries a significant burden of childhood morbidity especially among infants and young children in developing countries.

OBJECTIVES

To determine the clinical manifestations, outcomes, laboratory findings and antimicrobial susceptibility patterns in patients with invasive salmonellosis.

METHODS

A retrospective chart review was conducted among children 0-18 years of age diagnosed with invasive salmonellosis receiving care at Queen Sirikit National Institute of Child Health, Bangkok, Thailand, from 2001 to 2010.

RESULTS

We analyzed the records of 229 patients with culture-proven invasive salmonellosis. Sixty-three percent of cases had no documented underlying disease. Fever, diarrhea and respiratory symptoms were reported in 92%, 40% and 29% of cases, respectively. The spectrum of disease included isolated bacteremia (90%), clinical pneumonia (24.8%), bacteremia with meningitis (7.8%), septic arthritis (1.3%) and empyema thoracis (0.4%). Forty-seven of 57 cases presenting with clinical pneumonia had abnormal infiltrations on chest radiograph (20.5% of all cases). Despite the invasive nature of the illness, 53.1% of patients had a normal white blood cell count. Antimicrobial resistance was found among ampicillin (68.3%), chloramphenical (15.2%), trimethoprim-sulfamethoxazole (33.9%), ceftriaxone (17.4%) and ciprofloxacin (3%). The case fatality rate was 4.8%, 91% of whom had an underlying disease. Multivariate analysis indicated that age, underlying liver disease and presence of pneumonia were significant predictors of fatality.

CONCLUSIONS

Fever, diarrhea and respiratory symptoms were among the most common presenting symptoms of invasive nontyphoidal salmonellosis. Older age, hepatobiliary disease and presence of pneumonia were associated with increased risk of fatality. Resistance to third-generation cephalosporins poses a major concern for its use as empiric antimicrobial therapy for this condition.

Invasive non-typhoidal salmonella disease: an emerging and neglected tropical disease in Africa

Invasive strains of non-typhoidal salmonellae have emerged as a prominent cause of bloodstream infection in African adults and children, with an associated case fatality of 20-25%. The clinical presentation of invasive non-typhoidal salmonella disease in Africa is diverse: fever, hepatosplenomegaly, and respiratory symptoms are common, and features of enterocolitis are often absent. The most important risk factors are HIV infection in adults, and malaria, HIV, and malnutrition in children. A distinct genotype of Salmonella enterica var Typhimurium, ST313, has emerged as a new pathogenic clade in sub-Saharan Africa, and might have adapted to cause invasive disease in human beings. Multidrug-resistant ST313 has caused epidemics in several African countries, and has driven the use of expensive antimicrobial drugs in the poorest health services in the world. Studies of systemic cellular and humoral immune responses in adults infected with HIV have revealed key host immune defects contributing to invasive non-typhoidal salmonella disease. This emerging pathogen might therefore have adapted to occupy an ecological and immunological niche provided by HIV, malaria, and malnutrition in Africa. A good understanding of the epidemiology of this neglected disease will open new avenues for development and implementation of vaccine and public health strategies to prevent infections and interrupt transmission.

Differing burden and epidemiology of non-Typhi Salmonella bacteremia in rural and urban Kenya, 2006-2009

BACKGROUND

The epidemiology of non-Typhi Salmonella (NTS) bacteremia in Africa will likely evolve as potential co-factors, such as HIV, malaria, and urbanization, also change.

METHODS

As part of population-based surveillance among 55,000 persons in malaria-endemic, rural and malaria-nonendemic, urban Kenya from 2006-2009, blood cultures were obtained from patients presenting to referral clinics with fever ≥38.0°C or severe acute respiratory infection. Incidence rates were adjusted based on persons with compatible illnesses, but whose blood was not cultured.

RESULTS

NTS accounted for 60/155 (39%) of blood culture isolates in the rural and 7/230 (3%) in the urban sites. The adjusted incidence in the rural site was 568/100,000 person-years, and the urban site was 51/100,000 person-years. In both sites, the incidence was highest in children <5 years old. The NTS-to-typhoid bacteremia ratio in the rural site was 4.6 and in the urban site was 0.05. S. Typhimurium represented >85% of blood NTS isolates in both sites, but only 21% (urban) and 64% (rural) of stool NTS isolates. Overall, 76% of S. Typhimurium blood isolates were multi-drug resistant, most of which had an identical profile in Pulse Field Gel Electrophoresis. In the rural site, the incidence of NTS bacteremia increased during the study period, concomitant with rising malaria prevalence (monthly correlation of malaria positive blood smears and NTS bacteremia cases, Spearman's correlation, p = 0.018 for children, p = 0.16 adults). In the rural site, 80% of adults with NTS bacteremia were HIV-infected. Six of 7 deaths within 90 days of NTS bacteremia had HIV/AIDS as the primary cause of death assigned on verbal autopsy.

CONCLUSIONS

NTS caused the majority of bacteremias in rural Kenya, but typhoid predominated in urban Kenya, which most likely reflects differences in malaria endemicity. Control measures for malaria, as well as HIV, will likely decrease the burden of NTS bacteremia in Africa.

Decreasing incidence of severe malaria and community-acquired bacteraemia among hospitalized children in Muheza, north-eastern Tanzania, 2006-2010

BACKGROUND

The annual incidence and temporal trend of severe malaria and community-acquired bacteraemia during a four-year period in Muheza, Tanzania was assessed.

METHODS

Data on severely ill febrile children aged 2 months to 14 years from three prospective studies conducted at Muheza District Hospital from 2006 to 2010 was pooled and analysed. On admission, each enrolled child had a thin and thick blood film and at least one rapid diagnostic test for falciparum malaria, as well as a blood culture. The annual incidence of bacteraemia and severe malaria among children coming from Muheza was calculated and their temporal trend was assessed.

RESULTS

Overall, 1, 898 severe falciparum malaria and 684 bacteraemia cases were included. Of these, 1, 356 (71%) and 482 (71%), respectively, were from the referral population of Muheza. The incidence of falciparum malaria and all-cause bacteraemia in Muheza decreased five-fold and three-fold, respectively, from the first to the fourth year of surveillance (p < 0.0001). During this period, the median ages of children from Muheza admitted with severe malaria increased from 1.7 to 2.5 years (p < 0.0001). The reduction in all-cause bacteraemia was mainly driven by the 11-fold decline in the incidence of non-typhoidal salmonellosis. The annual incidences of Haemophilus influenzae and pneumococcal invasive bacterial infections decreased as well but were much fewer in number.

CONCLUSIONS

These results add to the growing evidence of the decline in malaria associated with a decrease in non-typhoidal salmonellosis and possibly other bacteraemias. Malarial prevention and control strategies may provide a greater benefit than the mere reduction of malaria alone.

Burden of rotavirus and other enteropathogens among children with diarrhea in Burkina Faso

OBJECTIVE

There is limited information available regarding the etiology of gastrointestinal infections in Burkina Faso. The aim of this study was to investigate the prevalence and epidemiology of enteric pathogens causing gastroenteritis in young children, with a focus on rotavirus, and to investigate the levels of malnutrition and other clinical factors in association with the severity of diarrhea.

METHODS

A prospective study was undertaken from May 2009 to March 2010, covering the rainy and dry seasons, at the Saint Camille Medical Center in Ouagadougou, Burkina Faso. A total of 309 children less than 5 years of age with diarrhea were enrolled and examined for rotavirus, bacterial, and parasitic infections, as well as clinico-epidemiological aspects.

RESULTS

At least one enteropathogen was detected in 57.9% (n=179) of the children. Of these, 32.4% had rotavirus infections, 16.8% bacterial infections (enteropathogenic Escherichia coli 9.7%, Shigella spp 5.8%, and Salmonella spp 2.3%), and 18.8% parasitic infections (Giardia lamblia 11.3%, Trichomonas intestinalis 6.8%, Entamoeba histolytica/dispar 1.3%). During the cold dry period from December 2009 to February 2010, we observed a large increase in diarrhea cases, which was mainly attributed to rotavirus infections, as 63.8% of these diarrhea cases were positive for rotavirus. In contrast, no rotavirus infection was observed during the rainy season (June-September 2009), when the frequency of parasitic infections was high. Rotavirus and parasitic infections were age-related, with rotavirus being more prevalent in young children (<12 months) and parasites more common in older children (>12 months), while bacteria were equally prevalent among all age groups. Rotavirus infections exhibited more severe symptoms compared to bacteria and parasites, and were associated with fever, vomiting, and severe dehydration. Malnutrition, especially acute malnutrition (wasting), was significantly associated with more severe symptoms in rotavirus-induced diarrhea. The undernourished children also exhibited a prolonged duration of diarrheal episodes.

CONCLUSION

This study demonstrates rotavirus as the main etiological agent in pediatric diarrhea in Burkina Faso, and further shows the great severity of rotavirus-induced diarrhea in undernourished children in Burkina Faso.

Systemic bacteraemia in children presenting with clinical pneumonia and the impact of non-typhoid salmonella (NTS)

Background

The diagnosis and antimicrobial treatment of pneumonia in African children in the absence of diagnostic means such as x-ray facilities or microbiological laboratories relies primarily on clinical symptoms presented by the patients. In order to assess the spectrum of bacterial pathogens, blood cultures were performed in children fulfilling the clinical criteria of pneumonia.

Methods

In total, 1032 blood cultures were taken from children between 2 months and 5 years of age who were admitted to a rural hospital in Ghana between September 2007 and July 2009. Pneumonia was diagnosed clinically and according to WHO criteria classified as "non-severe pneumonia" and "severe pneumonia" ("severe pneumonia" includes the WHO categories "severe pneumonia" and "very severe pneumonia").

Results

The proportion of bacteriaemia with non-typhoid salmonella (NTS) was similar in children with pneumonia (16/173, 9.2%) compared to children hospitalized for other reasons (112/859, 13%). NTS were the predominant organisms isolated from children with clinical pneumonia and significantly more frequent than Streptococcus pneumoniae (8/173, 4.6%). Nine percent (9/101) of children presenting with severe pneumonia and 10% (7/72) of children with non-severe pneumonia were infected with NTS. Nineteen out of 123 NTS isolates (15%) were susceptible to aminopenicillins (amoxycillin/ampicillin), 23/127 (18%) to chlorampenicol, and 23/98 (23%) to co-trimoxazole. All NTS isolates were sensitive to ceftriaxone and ciprofloxacin.

Conclusion

In Sub-saharan Africa, sepsis with NTS should be considered in children with symptoms of pneumonia and aminopenicillins might often not be the adequate drugs for treatment.

Community-acquired bloodstream infections in Africa: a systematic review and meta-analysis

Data on the prevalence and causes of community-acquired bloodstream infections in Africa are scarce. We searched three databases for studies that prospectively studied patients admitted to hospital with at least a blood culture, and found 22 eligible studies describing 58 296 patients, of whom 2051 (13.5%) of 15 166 adults and 3527 (8.2%) of 43 130 children had bloodstream infections. 1643 (29.1%) non-malaria bloodstream infections were due to Salmonella enterica (58.4% of these non-typhoidal Salmonella), the most prevalent isolate overall and in adults, and 1031 (18.3% overall) were due to Streptococcus pneumoniae, the most common isolate in children. Other common isolates included Staphylococcus aureus (531 infections; 9.5%) and Escherichia coli (412; 7.3%). Mycobacterium tuberculosis complex accounted for 166 (30.7%) of 539 isolates in seven studies that used mycobacterial culture techniques. HIV infection was associated with any bloodstream infection, particularly with S enterica and M tuberculosis complex bacteraemia. Where recorded, patients with bloodstream infections had an in-hospital case fatality of 18.1%. Our results show that bloodstream infections are common and associated with high mortality. Improved clinical microbiology services and reassessment of empirical treatment guidelines that account for the epidemiology of bloodstream infections might contribute to better outcomes.

A decline in the incidence of invasive non-typhoidal Salmonella infection in The Gambia temporally associated with a decline in malaria infection

Background

Malaria is a risk factor for invasive non-typhoidal Salmonella (NTS) infection in children. In the last 10 years, indices of malaria infection in The Gambia have fallen substantially.

Methods

We compared temporal trends of childhood malaria and NTS infection in two Gambian locations. In Fajara, on the coast, the incidence of NTS infection at three time points between 1979 and 2005 was compared to the percentage of malaria positive outpatient thick blood films and the percentage of admissions associated with malaria over time. In Basse, in the eastern part of the country, the incidence of NTS infection at three time points between 1989 and 2008 was compared to the prevalence of malaria parasitaemia at four time points between 1992 and 2008.

Results

The estimated incidence of NTS infection in Fajara fell from 60 (1979–1984) to 10 (2003–05) cases per 100,000 person years. The proportion of outpatients in Fajara with suspected malaria who were parasitaemic fell from 33% (1999) to 6% (2007) while the proportion of admissions associated with malaria fell from 14.5% (1999) to 5% (2007). In Basse, the estimated incidence of NTS infection fell from 105 (1989–1991) to 29 (2008) cases per 100,000 person years while the prevalence of malaria parasitaemia fell from 45% (1992) to 10% (2008). The incidence of pneumococcal bacteraemia in Fajara and Basse did not fall over the study period.

Conclusions

These data support an association between malaria and NTS infection. Reductions in malaria infection may be associated with reduced rates of invasive childhood NTS infection.

Invasive salmonellosis among children admitted to a rural Tanzanian hospital and a comparison with previous studies

Background

The importance of invasive salmonellosis in African children is well recognized but there is inadequate information on these infections. We conducted a fever surveillance study in a Tanzanian rural hospital to estimate the case fraction of invasive salmonellosis among pediatric admissions, examine associations with common co-morbidities and describe its clinical features. We compared our main findings with those from previous studies among children in sub-Saharan Africa.

Methodology/Principal Findings

From 1 March 2008 to 28 Feb 2009, 1,502 children were enrolled into the study. We collected clinical information and blood for point of care tests, culture, and diagnosis of malaria and HIV. We analyzed the clinical features on admission and outcome by laboratory-confirmed diagnosis. Pathogenic bacteria were isolated from the blood of 156 (10%) children, of which 14 (9%) were S. typhi, 45 (29%) were NTS and 97 (62%) were other pathogenic bacteria. Invasive salmonellosis accounted for 59/156 (38%) bacteremic children. Children with typhoid fever were significantly older and presented with a longer duration of fever. NTS infections were significantly associated with prior antimalarial treatment, malarial complications and with a high risk for death.

Conclusions/Significance

Invasive salmonellosis, particularly NTS infection, is an important cause of febrile disease among hospitalized children in our rural Tanzanian setting. Previous studies showed considerable variation in the case fraction of S. typhi and NTS infections. Certain suggestive clinical features (such as older age and long duration of fever for typhoid whereas concomitant malaria, anemia, jaundice and hypoglycemia for NTS infection) may be used to distinguish invasive salmonellosis from other severe febrile illness.

Both hemolytic anemia and malaria parasite-specific factors increase susceptibility to Nontyphoidal Salmonella enterica serovar typhimurium infection in mice

Severe pediatric malaria is an important risk factor for developing disseminated infections with nontyphoidal Salmonella serotypes (NTS). While recent animal studies on this subject are lacking, early work suggests that an increased risk for developing systemic NTS infection during malaria is caused by hemolytic anemia, which leads to reduced macrophage microbicidal activity. Here we established a model for oral Salmonella enterica serotype Typhimurium challenge in mice infected with Plasmodium yoelii nigeriensis. Initial characterization of this model showed that 5 days after coinoculation, P. yoelii nigeriensis infection increased the recovery of S. Typhimurium from liver and spleen by approximately 1,000-fold. The increased bacterial burden could be only partially recapitulated by antibody-mediated hemolysis, which increased the recovery of S. Typhimurium from liver and spleen by 10-fold. These data suggested that both hemolysis and P. yoelii nigeriensis-specific factors contributed to the increased susceptibility to S. Typhimurium. The mechanism by which hemolysis impaired resistance to S. Typhimurium was further investigated. In vitro, S. Typhimurium was recovered 24 h after infection of hemophagocytic macrophages in 2-fold-higher numbers than after infection of mock-treated macrophages, making it unlikely that reduced macrophage microbicidal activity was solely responsible for hemolysis-induced immunosuppression during malaria. Infection with P. yoelii nigeriensis, but not antibody-mediated hemolysis, reduced serum levels of interleukin-12p70 (IL-12p70) in response to S. Typhimurium challenge. Collectively, studies establishing a mouse model for this coinfection suggest that multiple distinct malaria-induced immune defects contribute to increased susceptibility to S. Typhimurium.

Antibiotic resistance among bacterial pathogens in Central Africa: a review of the published literature between 1955 and 2008

A systematic review of the published literature on bacterial resistance in Central Africa between 1955 and 2008 was performed. Eighty-three publications from seven countries were retrieved, the majority presenting data on enteric and other gram-negative pathogens. Despite methodological limitations in many studies, alarming resistance rates are noted in nearly all pathogens. Of special concern are multidrug resistance in Shigella and Salmonella spp. and the emergence of meticillin-resistant Staphylococcus aureus, high-level penicillin-resistant Streptococcus pneumoniae and extended-spectrum beta-lactamases among gram-negative pathogens. These findings make clear that the Central African region shares the worldwide trend of increasing antimicrobial resistance and is in urgent need of sound surveillance based on competent and affordable microbiology to provide clear data on antimicrobial resistance. These data could enable redaction of local treatment guidelines and fuel national and regional policies to contain antimicrobial resistance.

Typhoid fever in children in Africa

Estimates for the year 2000 suggested that there were approximately 21.5 million infections and 200,000 deaths from typhoid fever globally each year, making the disease one of the most serious infectious disease threats to public health on a global scale. However, these estimates were based on little data, especially from Africa. Global prominence and high-profile outbreaks have created the perception in Kenya that typhoid is a common cause of febrile illness. The Widal test is used widely in diagnosis. We have reviewed recent literature, taking the perspective of a healthcare provider, to collate information on the prevalence of typhoid in children particularly, and to explore the role of clinical diagnosis and diagnosis based on a crude, but common, interpretation of the Widal test. Data suggest that typhoid in children in rural Africa is uncommon, perhaps 100 times or 250 times less common than invasive disease because of Haemophilus influenzae or Streptococcus pneumoniae, respectively. Frequent use of the Widal test may result in many hundreds of over-treatment episodes for every true case treated and may perpetuate the perception that typhoid is common. Countries such as Kenya need better bacterial disease surveillance systems allied to better information for healthcare providers to promote appropriate decision-making on prevention and treatment strategies.

Bacteraemia in patients admitted to an urban hospital in West Africa

Background

Few studies on bacteraemia in Africa have been published. We aimed to prospectively identify the causative organisms of bacteraemia in The Gambia and their relation to clinical diagnoses, outcome and antimicrobial susceptibility.

Methods

Between November 2003 and February 2005 we studied those admitted to the Medical Research Council hospital who were suspected of having bacteraemia. We documented clinical features, outcome, pathogens identified and their susceptibility patterns, and searched for factors associated with bacteraemia.

Results

871 patients were admitted and had a blood culture taken. The median age was 2 years (range 2 months to 80 years) and 36 of 119 tested were HIV positive; 54.5% were male. 297 (34%) had a positive result and 93 (10.7% overall) were considered a genuine pathogen. Those with bacteraemia were more likely to die in hospital (OR 2.79; 1.17–6.65, p = 0.017) and to have a high white cell count (WCC; OR 1.81;95% CI 1.09–3.02; p = 0.022). Three organisms accounted for 73% of bacteraemias: Streptococcus pneumoniae (45.2%), Staphylococcus aureus (18.3%) and Escherichia coli (9.7%) while non-typhoidal salmonellae (NTS) accounted for 8.6%. Antimicrobial susceptibility of S. pneumoniae was very high to penicillin (97.5%); high resistance was found to co-trimoxazole. S. aureus was generally highly susceptible to cloxacillin, gentamicin and chloramphenicol. E. coli and NTS were all susceptible to ciprofloxacin and mostly susceptible to gentamicin. Thirteen (33%) S. pneumoniae isolates were of serotypes contained in a 7-valent pneumococcal conjugate vaccine and 20 (51.3%) were of the same serogroup.

Conclusion

In The Gambia, those with bacteraemia are more likely than those without to die in hospital and to have a raised peripheral blood WCC. S. pneumoniae is the most common organism isolated. Introduction of a pneumococcal conjugate vaccine can be expected to lead to a reduction in disease incidence.

Invasive multidrug-resistant non-typhoidal Salmonella infections in Africa: zoonotic or anthroponotic transmission?

In Africa, multidrug-resistant non-typhoidal salmonellae (NTS) are one of the leading causes of morbidity and high mortality in children under 5 years of age, second in importance only to pneumococcal disease. The authors studied NTS isolates from paediatric admissions at two hospitals in Nairobi, Kenya, and followed the index cases to their homes, where rectal swabs and stools from parents and siblings, and from animals in close contact, were obtained. The majority of NTS obtained from cases were Salmonella enterica serotype Typhimurium (106 out of 193; 54.9%) and Salmonella enterica serotype Enteritidis (64; 33.2%), a significant proportion (34.2%) of which were multiply resistant to three or more antibiotics, including ampicillin, tetracycline, cotrimoxazole and chloramphenicol. Only 23.4% of NTS were fully susceptible to all 10 antibiotics tested. Of the 32 NTS obtained from contacts (nine adults and 23 children) at the homes of index cases, 21 (65.6%) isolates were similar by antibiotic-susceptibility profiles and plasmid content, and their XbaI- and SpeI-digested chromosomal DNA patterns were indistinguishable from those of the corresponding index cases. Only three out of 180 (1.7%) samples from environmental sources, including animals, soil, sewers and food, contained NTS matching those from corresponding index cases. The carriage of NTS in an asymptomatic population was represented by 6.9% of human contacts from 27 out of 127 homes sampled. This population of carriers may represent an important reservoir of NTS that would play a significant role in the epidemiology of community-acquired NTS bacteraemia in children.

Salmonella bacteremia in Kenyan children

BACKGROUND

Nontyphoidal Salmonella spp. are among the leading causes of childhood bacteremia in sub-Saharan Africa, yet there are few published clinical series, and the risk factors for acquiring infection are not fully understood.

METHODS

We examined data from 166 cases of nontyphoidal Salmonella bacteremia identified during a large prospective study of bacteremia among all children admitted to a district hospital in Kenya. We also investigated the importance of comorbidities, including current malaria parasitemia, recent malaria (detectable Plasmodium falciparum histidine rich protein 2 in the absence of parasitemia), sickle cell disease, malnutrition and human immunodeficiency virus (HIV) infection.

RESULTS

Nontyphoidal Salmonella bacteremia was associated with severe malnutrition (33% cases), HIV infection (18% cases), a history of illness >7 days, recent hospital admission, splenomegaly, anemia and recent (but not current) malaria but was not associated with diarrhea. Seventy-seven (46%) children with nontyphoidal Salmonella bacteremia fulfilled World Health Organization clinical criteria for a diagnosis of pneumonia. Independent risk factors for death were diarrhea, tachypnea, HIV infection, severe malnutrition, meningitis and young age.

CONCLUSIONS

Clinical diagnosis of invasive nontyphoidal Salmonella infection in African children is difficult without microbiology facilities because clinical features overlap with other conditions. The common risk factors for nontyphoidal Salmonella infection differ from developed countries, with high a prevalence of malnutrition, HIV, malaria and anemia. Children with nontyphoidal Salmonella infection who fulfill World Health Organization clinical criteria for severe pneumonia may receive ineffective therapy in the form of penicillin.

Problem pathogens: extra-intestinal complications of Salmonella enterica serotype Typhi infection

Typhoid fever, caused by Salmonella enterica seroptype Typhi (S typhi), has an estimated worldwide prevalence of 12-33 million cases. The pathogenesis of this disease depends on the ingested inoculum size of S typhi, the virulence of the strain, the host's immune response and previous exposure, and local protective factors. Numerous extra-intestinal complications can occur with S typhi infection, including the involvement of the central nervous system (3-35%), cardiovascular system (1-5%), pulmonary system (1-86%), bone and joints (< or =1%), hepatobiliary system (1-26%), genitourinary system (<1%), and others. Due to an increase in multidrug-resistant S typhi, fluoroquinolones and third-generation cephalosporins have been increasingly used for typhoid fever and its complications. We describe the epidemiology, clinical manifestations, pathogenesis, and treatment of extra-intestinal S typhi infections.

Overlapping epidemiologies of hepatitis A and typhoid fever: the needs of the traveler

Hepatitis A and typhoid fever are endemic infectious diseases in many parts of the world. They share a common, simple mode of transmission--the fecal--oral route-associated with poor hygiene. The low endemicity of both diseases in developed countries, and the rise in travel to exotic destinations for business and leisure, mean that increasing numbers of travelers are being exposed to infection. Effective, established vaccines are available against both diseases, and recently new formulations combining both vaccines in one injection have been licensed. We review the present epidemiologic situation for both diseases, to determine the necessity to routinely vaccinate travelers against both diseases.

Increasing prevalence of multidrug-resistant non-typhoidal salmonellae, Kenya, 1994–2003

Over the last decade there has been a steady increase in the proportion of multidrug resistance among non-typhoidal salmonellae (NTS) isolated from adult patients with bacteraemia in Kenya. The prevalence of NTS multiply resistant to all commonly available drugs including ampicillin, streptomycin, co-trimoxazole, chloramphenicol and tetracycline rose from 31% in 1994 to 42% at present, with concomitantly higher MICs of each drug. Resistance is encoded on large self-transferable 100-110 kb plasmids. Pulsed field gel electrophoresis of XbaI and SpeI digested chromosomal DNA revealed three main digest patterns for Salmonella enterica serotype Typhimurium and two main patterns for Salmonella enterica serotype Enteritidis. Although the genotypes of NTS remained fairly stable over the last decade, the large increase in MICs of all commonly used drugs and increased MICs of ciprofloxacin, poses a major challenge for treatment of invasive NTS infection.

Salmonella bacteraemia in Turkish children: 37 cases seen in a university hospital between 1993 and 2002

The aim of the study was to evaluate the clinical pattern of Salmonella bacteraemia in Turkish children. From 1993 to 2002, all children with a blood culture positive for Salmonella were retrospectively evaluated in the Division of Paediatric Infectious Diseases in Ankara University School of Medicine. All Salmonella isolates were serotyped and investigated for antimicrobial susceptibility. During the 10-year study period, 40 patients with Salmonella bacteraemia were identified. Of 37 eligible children, eight had enteric fever and 29 had non-typhoidal salmonellosis. Salmonella typhimurium was the most common serotype in the group with non-typhoidal salmonellosis. No significant differences were found between the enteric fever and non-typhoidal salmonellosis groups with regard to clinical features, laboratory findings and outcome, except in mean platelet counts and mean serum alanine aminotransferase (ALT) levels. In vitro resistance rates of Salmonella strains were low. Outcome was excellent in all but one child with hydrocephalus and gross neurological sequelae owing to meningitis. Salmonella bacteraemia is relatively uncommon in Turkish children. Differentiating between enteric fever and non-typhoidal Salmonella bacteraemia on clinical grounds is difficult.

Antibiotic resistance in bacteria - an emerging public health problem

The discovery and eventual introduction of anti-microbial agents to clinical medicine was one of the greatest medical triumphs of the twentieth century that revolutionized the treatment of bacterial diseases. However, the gradual emergence of populations of antibiotic-resistant bacteria resulting from use, misuse and outright abuse of antibiotics has today become a major public health problem of global proportions. This review paper examines the origins and molecular epidemiology of resistance genes, global picture of antibacterial resistance, factors that favour its spread, strategies for its control, problems of control and the consequences of failure to contain antibiotic resistance in bacteria.

Epidemiology of bacterial resistance in gastro-intestinal pathogens in a tropical area

During 1999-2000 a total of 4131 faecal specimens were collected and analysed at the medical centre St. Camille at Ouagadougou. Eight hundred and twenty-six (8.0%) grew significant bacteria. Escherichia coli (35%), Salmonella spp. (15%) and Shigella spp. (10%) were most frequently isolated. A large number of E. coli strains were resistant to aminopenicillins (>90%) and cotrimoxazole (80%); for Yersinia spp the resistance was 80 and 25%, respectively. Norfloxacin was the most active antibiotic but was rarely used. The study showed that it is necessary to create antibiotic-resistance surveillance centres in developing countries so that therapy may be appropriate and the spread of antibiotic resistance to other developed countries via increased emigration may be reduced.

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.

Systemic nontyphoidal Salmonella infection in normal infants in Thailand

BACKGROUND

The relative paucity of information about systemic nontyphoidal Salmonella (NTS) infection in infants without an underlying disease prompted this study.

METHODS

Infants without an underlying disease, who had positive cultures for NTS from their normally sterile sites during 1978 through 1998, were included. Their medical records were reviewed.

RESULTS

The study included 75 eligible infants; 68 (91%) had positive blood cultures. The spectrum of disease included transient bacteremia (5), bacteremia without localized infection (37), bone and joint infection (5) and meningitis (28); 53 and 88% of infants were < or =3 and < or =6 months old, respectively. All infants with localized infection were < or =7 months old, and infants with meningitis were 3.35+/-1.87 (mean +/- SD) months old. In bacteremic infants risks for localized infection and meningitis were 30 and 24%, respectively. Abnormal neurologic findings were the only predictor for meningitis. Relapse of meningitis occurred in two infants despite treatment with cefotaxime for 4 and 6 weeks. Severe neurologic deficit occurred in 21% of infants with meningitis. Of 11 infants with meningitis who received early treatment at this tertiary care center, 1 died but none had severe neurologic deficits; whereas of 17 referred cases, 2 died and 6 had severe neurologic abnormalities. No death occurred in infants without meningitis.

CONCLUSION

Systemic NTS infection in normal infants has a variable disease spectrum. Infants 0 to 6 months of age are at high risk for localized infection, especially meningitis.

Bacteraemia and mortality among adult medical admissions in Malawi--predominance of non-typhi salmonellae and Streptococcus pneumoniae

OBJECTIVES

The high seroprevalence of HIV in Malawi might be expected to alter the pattern of pathogens isolated from bacteraemic patients. We aimed to describe the frequency and seasonal pattern of bacterial isolates from blood, their antibiotic susceptibility, and patient outcome, in order to provide data on which to base empirical antibiotic therapy and further studies of pathogenesis.

METHODS

Over a 12-month period, blood cultures were taken from all febrile adult medical admissions to Queen Elizabeth Central Hospital, Blantyre.

RESULTS

A total of 2789 out of 9298 adult general medical admissions had blood culture performed, of whom 449 (16.1%) grew significant pathogens. Non-typhi salmonellae (NTS) (37%) and Streptococcus pneumoniae (30%) were the two commonest isolates. Mortality was 18% among general medical admissions and 38% among bacteraemic patients. Mortality for individual pathogens was: NTS 33%; S. pneumoniae 36%; Escherichia coli 54%; Klebsiella spp. 58%; Neisseria meningitidis 44%; Salmonella typhi 17%. Despite an overwhelming association between the major pathogens and HIV infection (95% of S. pneumoniae cases and 92% of NTS cases were seropositive for HIV), a seasonal pattern was preserved. Streptococcus pneumoniae was more frequently isolated in the cold dry months, while STM isolates increased following a rise in temperature. A case of bacteraemia with Vibrio cholerae (serotype 01) was detected during a cholera outbreak in the rainy season. Although S. pneumoniae isolates were relatively susceptible to penicillin (88%) and chloramphenicol (74%), S. typhimurium isolates were fully susceptible only to chloramphenicol.

CONCLUSIONS

This large study confirms the dominance of NTS and S. pneumoniae in bacteraemia in an area affected by HIV-1 and allows comparison of mortality by individual pathogens. It demonstrates a preserved seasonal pattern of bacteraemia for these major pathogens, despite an overwhelming association with HIV infection.

Communicable disease surveillance with limited resources: the scope to link human and veterinary programmes

Zoonoses are an important cause of human disease in much of Africa, but limitations in current diagnosis and surveillance strategies restrict the effectiveness of control and prevention programmes. Outbreaks of disease, ranging from Ebola virus infection to Rift Valley Fever, that have occurred recently in Africa have demonstrated the need for improved disease surveillance and monitoring. Strategies are suggested for co-ordinating human and animal disease surveillance programmes, at the district and regional level, to make more effective use of limited resources.

Extra-intestinal non-typhoidal Salmonella infections in children

Extra-intestinal non-typhoidal Salmonella (NTS) infections are uncommon in developed countries but common in developing ones. The risk factors, clinical features and outcome of children admitted to the Department of Paediatrics, University of Malaya Medical Center, Kuala Lumpur from 1978 to 1998 with extra-intestinal NTS infections were reviewed. All positive cultures of NTS, blood, cerebrospinal fluid, urine, synovial, pericardial and other body secretions (except stools), were included. Of the 98 cases reviewed, 56 were boys and 42 girls. The mean age was 2.1 years (range: newborn to 14 years). Twenty-seven children were severely immunocompromised and 21 had underlying chronic medical disorders. Bacteraemia was the most commonly detected type of infection and meningitis the commonest focal infection. The overall mortality rate was 15%. An immunocompromised state or underlying chronic medical disorder was associated with increased mortality. The three serotypes most commonly isolated were S. enteritidis, S. paratyphi B and S. typhimurium. Most isolates were sensitive to antibiotics commonly used in salmonellosis.