Salmonella and Shigella gastroenteritis at a public teaching hospital in Nairobi, Kenya

Antimicrobial susceptibility pattern, and associated factors of Salmonella and Shigella infections among under five children in Arba Minch, South Ethiopia

Background

Diarrheal diseases continue to be the major cause of morbidity and mortality among children under 5 years. Salmonella and Shigella specious are the major enteric pathogen causing diarrhea among children worldwide. Examination of stool sample is the most sensitive method to diagnose diarrheal disease in children. This study aimed to determining the prevalence, antimicrobial susceptibility pattern and associated factor of Salmonella and Shigella infection among under five children.

Methods

A cross sectional study was conducted on under 5 years children attending Arba Minch town. Pre-tested and structured questionnaire was used for collecting data about socio-demographic characteristics and associated factors. Stool sample was used to isolate and identified the pathogen. Antimicrobial susceptibility test was performed for isolated Salmonella and Shigella specious. A logistic regression analysis was used to see the association between different variables and outcome variable. Odds ratio with 95% CI was computed to determine the presence and strength of the association.

Results

A total of 167 under five children were included in the study. About 57% of participants were males with the mean age of 32 months. The overall prevalence of Salmonella and Shigella species infection was 17.45% with 12.6% Salmonella species. The isolates were resistant to common antibiotics such as Amoxicillin, Erythromycin, Chloramphenicol, Clindamycin, Norfloxacin, Ciprofloxacin, Cotrimoxazole, and Gentamycin. Urban resident [AOR = 7.11; 95% CI (2.3, 22.2)], month income < 1000 Ethiopian birr [AOR = 6.5; 95% CI (2.0, 21.4)], absence of waste disposal system [AOR = 3.3; 95% CI (1.2, 9.3)], poor hand washing habit [AOR = 6.0; 95% CI (2.0, 18.2)], untrimmed finger nail [AOR = 3.7; 95% CI (1.4, 10.6)], and use of napkin [AOR = 3.2; 95% CI (1.1, 9.3)] had significant association with Salmonella and Shigella infection.

Conclusion

Salmonella and Shigella species infections were higher as compared the national prevalence. This study also revealed that the enteric infection were significantly associated with finger nail status, residence, hand washing practice, month income of parents, usage of napkin after toilet, and absence of waste disposal system. Therefore, working on identified associated factors and regular drug susceptibility test is mandatory to reduce the problem.

Diarrhoeagenic Escherichia coli as a predominant cause of paediatric nosocomial diarrhoea in India

Intestinal nosocomial infections remain a major concern in paediatric wards leading to increased morbidity and mortality. This study determined the aetiological and epidemiological profile of nosocomial diarrhoea (ND) among children admitted to a hospital in India. During the period of January 2008 to June 2009, we consecutively enrolled 100 children between the age of 2 months and 14 years who developed ND as defined by the Centers for Disease Control and Prevention. A control group of patients matched for age and severity score but with no diarrhoea at admission or during their hospital stay (n=50) were also enrolled. Stool samples were cultured for various pathogens using standard protocols. Clostridium difficile toxins and rotavirus antigen were detected using commercial ELISAs. Detection of diarrhoeagenic Escherichia coli was carried out by multiplex PCR assay. All patient details were noted. In this study, males predominated (77%), and 56% children were <1 year of age and 96% were <5 years. The mean duration of diarrhoea and hospitalization in the case group was 3.2 days and 27.5 days, respectively. Malignancy and nasogastric tube usage were significant underlying factors for the development of ND. Diarrhoeagenic E. coli was the commonest agent (47%: enterotoxigenic E. coli, enteroaggregative E. coli and enteropathogenic E. coli were isolated in 22, 18 and 7% of patients, respectively). C. difficile toxin was seen in 9% of cases, whilst rotavirus was found in 8% of cases. Although rotavirus and C. difficile are major causative agents of hospital-acquired diarrhoea in the developed world, in this setting diarrhoeagenic E. coli was responsible for the majority of cases of hospital-acquired diarrhoea. ND was most common in children aged <5 years.

Invasive non-Typhi Salmonella disease in Africa

Invasive non-Typhi Salmonella is endemic to sub-Saharan Africa, where it is a leading cause of bloodstream infection. Some host risk factors have been established, but little is known about environmental reservoirs and predominant modes of transmission, so prevention strategies are underdeveloped. Although foodborne transmission from animals to humans predominates in high-income countries, it has been postulated that transmission between humans, both within and outside health care facilities, may be important in sub-Saharan Africa. Antimicrobial resistance to ampicillin, trimethoprim-sulfamethoxazole, and chloramphenicol is common among non-Typhi Salmonella strains; therefore, wider use of alternative agents may be warranted for empirical therapy. Development of vaccines targeting the leading invasive non-Typhi Salmonella serotypes Typhimurium and Enteritidis is warranted. The clinical presentation of non-Typhi Salmonella bacteremia is nonspecific and, in the absence of blood culture, may be confused with other febrile illnesses, such as malaria. Much work remains to be done to understand and control invasive non-Typhi Salmonella disease in sub-Saharan Africa.

Nosocomial outbreak of diarrhoea by enterotoxigenic Escherichia coli among preterm neonates in a tertiary care hospital in India: pitfalls in healthcare

An outbreak of watery diarrhoea accompanied by low-grade fever and weight loss in 16 preterm neonates (age range 2-20 days) admitted to a neonatal intensive care unit (NICU) over four days in August 2000 is reported. Escherichia coli having similar antibiograms were identified on routine bacterial stool cultures in 14 (87.5%) neonates and none of the other known enteropathogens were detected. An investigation was undertaken to trace the source of infection. Surveillance cultures of swabs from the utensils used to prepare milk feed, culture of the formula feed and all items handled by one particular cook yielded growth of E. coli as did culture of his hand swabs and faecal sample. The causative agent was identified as enterotoxigenic E. coli (ETEC) as toxin production could be demonstrated by reverse passive latex agglutination in all the strains of E. coli isolated both from the infected neonates and the source of infection. The outbreak was effectively controlled by appropriate therapy and institution of proper measures of hygiene after identification of the source of infection.

[Contribution of the laboratory to the epidemiologic study of bacterial infections]

The laboratory plays a significant role in the epidemiologic investigations by the comparative analysis of the bacterial strains involved in the outbreaks. Recently, the use of molecular analysis methods provided better performance than traditional phenotypic methods which are still used as preliminary tests because of their relatively low cost and technical simplicity. These analyses deal with either the whole chromosome of the bacterium, plasmids or particular genes. The classification of these methods runs up against the lack of consensus concerning their nomenclature. A clearer denomination based upon the technique responsible for revealing the polymorphisms of these various targets, makes it possible to divide these methods in two principal groups: methods of RFLP (based on the fragments resulting from digestion with restriction enzymes) and methods of AFLP (based on the products of amplification by PCR). The knowledge of the typability of the strains and the qualities of these various methods, particularly their discriminatory power, is essential to the accuracy of the laboratory analysis in the investigations of outbreaks.

Methods for the differentiation of microorganisms

Advances in analytical and diagnostic assays based on novel nucleic acid analyses techniques have revolutionized the application of molecular differentiation of microorganisms. Phenotypic typing schemes are now broadly supplemented by new genotyping methods which allow a more refined and detailed differentiation of closely related microorganisms, bacterial strains, isolates and pathogens on the DNA level. Bio-, sero- and phagetyping, antibiotic susceptibility tests, immunoblotting as well as multilocus enzyme- or polyacrylamide gel electrophoresis are now supported by the analysis of plasmid or chromosomal DNA restriction profiles, ribotyping, pulsed-field gel electrophoresis and polymerase- or ligase-chain reaction-based methods or direct sequencing technique to differentiate microorganisms. Some of these molecular techniques are also used in the field of virology to analyse and differentiate closely related sub- or genotypes. Few examples for the analysis and investigation of these usually small genomes will also be given.

Nosocomial transmission of Shigella dysenteriae type 1

An outbreak of dysentery due to Shigella dysenteriae type 1 occurred in a chronic care psychiatric institution in Durban, South Africa. Of the 10 patients who developed dysentery, 4 (40%) died. S. dysenteriae type 1 was isolated from stool samples from two of the four patients tested and ribotyping showed that these isolates were identical but differed from other community acquired strains. The isolates were resistant to ampicillin, chloramphenicol, tetracycline and co-trimoxazole. Infection control measures including isolation, cohort nursing and strict hand disinfection resulted in rapid control of the outbreak.

Role of molecular epidemiology in infection control

Molecular typing methods have enabled infection control personnel to investigate outbreaks and endemic nosocomial infections more quickly and thoroughly than they could have with basic epidemiologic and microbiologic methods. This article reviews molecular typing methods that have been used successfully in the practice of hospital epidemiology. Included is an explanation of the basic principles of these methods and a description of their strengths and weaknesses.

Subtyping of Shigella sonnei for tracing nosocomial transmission

Nosocomial transfer of Shigella spp. occurred between two patients sharing the patient room and toilet in a ward for internal medicine. Both patients had travelled abroad shortly before the onset of illness. Based on the epidemiology of Shigella sonnei strains imported into Finland, nosocomial infection was strongly suspected. The isolates of S. sonnei were subtyped using ribotyping, plasmid analysis and antibiotic resistance patterns. The greatest discrimination between the strains was achieved by ribotyping. The results of the typing scheme confirmed the nosocomial transmission of S. sonnei. The outbreak did not spread further within the ward. The importance of isolation of a patient with diarrhoea in a hospital setting is emphasized.