Cary blair transport medium

1020 subjects (850 diarrhea cases and 170 healthy controls) were recruited into this study. Each stool specimen was collected with sterile sampling cups using sterile cotton swabs, and then was transferred to the laboratory of Yunnan Provincial Center for Disease Control and Prevention in Cary Blair Transport Medium (Oxoid Ltd, Basingstoke, UK) within 12 h. A structured questionnaire was used to elucidate the following information from each diarrhea case and healthy control after the stool samples were collected: clinical manifestations associated with diarrhea (e.g. vomiting, fever, and/or dehydration), demographic data (age, sex, and residence), and types of stool samples (watery, mucousy, or bloody, or other form).

Chicken faecal samples were directly collected in specific specimen collection tubes following all safety precautions and aseptic techniques. For long distance transport, faeces samples were dipped into the Cary Blair transport medium (Oxoid, UK) before being transported to the laboratory. For bacterial isolation, approximately one gram of chicken-faeces was mixed in 400 μL of phosphate-buffered saline (PBS), and one loopful of diluted sample was streaked on MacConkey agar (Oxoid, UK) for growth of Gram-negative enteric bacilli. For the detection of Salmonella and Shigella, the diluted chick-droppings were enriched in Rappaport Vassiliadis soya broth (RVS Broth, Oxoid, UK) overnight and streaked separately on Salmonella-Shigella (SS) agar (Oxoid, UK) medium. After overnight incubation at 37 °C, distinct single colonies were picked and cultured again on tryptone soya agar (Lyophilchem, Italy) to prepare a pure-culture repository, which was stored at -80ºC. The purified bacterial colonies were identified by conventional biochemical procedures followed by a rapid biochemical-test kit (API 20E, BioMérieux, Durham, NC). Bacterial identification was validated further by 16S rDNA analyses.

A total of 347 household pooled fecal samples were collected from households: humans (n = 99), cattle (n = 135), sheep (n = 30), goats (n = 14), and poultry (n = 69). Pooled human stool samples were collected only from individuals who were most closely associated with the management of the livestock. Water samples (n = 172) were collected from the 99 households: surface water (n = 9), municipal pipe water (n = 84), ground water (n = 16), and stored water (n = 63).
A sterile cotton swab moistened with nutrient broth was used to transfer ~7–10 g of the pooled fecal samples into a 15 ml screw-capped falcon tube containing Cary-Blair Transport Medium (Oxoid). Fecal samples from individual animals were collected either directly from rectum or floor of the livestock housing immediately after an animal defecated. Samples were transported to the Microbiology Laboratory of Akililu Lemma Institute of Pathobiology (ALIPB), Addis Ababa University (AAU), and processed within 4–6 h of collection.

A total of 956 samples were collected from 286 households in the Karatu district wards. Of these, 286 were from chickens, 284 from humans, and 285 from soil (Table 1). Sterile cotton swabs were used to collect cloaca swabs from randomly picked scavenging chickens and human nasal swabs in households. Soil samples were randomly collected from five points in the household yards and mixed to compose one pooled soil sample [26 (link)]. Thereafter, cloaca and human nasal swabs were stored in sterile containers at −4°C and transported using Cary Blair transport medium and trypticase soy broth medium (Oxoid, Basingstoke, UK), respectively, to the Tanzania Veterinary Laboratory Agency (TVLA)–Arusha laboratory for processing within four hours after collection.

Chicken meat and cloaca swabs were collected aseptically using sterile cotton swabs and placed into a sterile tube containing 5 mL of Cary Blair transport medium (Oxoid, Basingstoke, UK). The collected samples were transported in a cool box at 2 to 8 °C containing a thermometer and were processed within 2 h of collection in the Microbiology Teaching Laboratory of the Muhimbili University and Allied Sciences (MUHAS).

Freshly passed stool and rectal swab was collected, placed immediately in Cary Blair transport medium (Oxoid Ltd, Basingstoke, UK) and transported to the laboratory within six hours of collection. For identification of Shigella and Salmonella species, specimens were placed in Selenite F enrichment broth (Oxoid) and incubated at 37°C for 24 hours, then subcultured onto deoxycholate agar (DCA) and xylose lysine deoxycholate agar (XLD) (Oxoid) agar at 37°C for 18-24 hours. The growth of Salmonella and Shigella species was detected by their characteristic appearance on XLD agar (Shigella: red colonies, Salmonella red with a black centre) and DCA (Shigella: pale colonies, Salmonella black centre pale colonies). The suspected colonies were further tested through a series of biochemical tests to identify Shigella and Salmonella species [21 ].