For example, Kaltoft et al. [48] demonstrated that a serum broth (beef infusion supplemented with horse serum and blood) improved the ability of traditional methods to detect multiple serotypes. Similarly, Carvalho et al. [49] found that an enrichment step in Todd Hewitt broth supplemented with yeast extract and rabbit serum increased Selleck Veliparib the proportion of specimens with pneumococcus identified, as well as increasing the detection of multiple serotypes by culture and molecular methods. However, there are some remaining

concerns with broth culture-amplification. The pneumococci may be overgrown by other species, and not all pneumococcal strains or serotypes grow at the same rate in vitro [50], [51] and [52]. Moreover, broth culture enrichment may reduce detection of co-colonization of other species [53], or may not be appropriate for all sample types. In addition, some media components (such as animal serum) may be difficult to access in developing countries. There is insufficient evidence to make a recommendation regarding inclusion of a broth culture-based enrichment

step for the detection of pneumococci. Quantification of pneumococcal load should not be determined using samples that have undergone see more broth enrichment. Whole-genome amplification methods may overcome limitations of low amounts of DNA. It would be useful to optimize broth culture-amplification (e.g. by including a selective agent), and to test the effects of broth-culture amplification on culture and molecular-based identification and serotyping methods. These recommendations establish the minimum set of criteria to determine the presence of pneumococci, much and the dominant pneumococcal serotype, in order to ascertain the prevalence of pneumococcal carriage and the serotypes present in the overall population under study. Given this objective, there are two main issues to consider: how many colonies to

pick, and how to select them. Detecting multiple serotype carriage is important for some epidemiologic questions, but serotyping a few colonies is an insensitive method to detect the true prevalence of multiple serotype carriage [54], [55] and [56]. For colony selection, the truly random approach (e.g. where the STGG medium is diluted and spread on agar plates to obtain single colonies, then all the colonies are numbered and selected using a list of random numbers) may be optimal statistically, but is considered impractical for routine use. Choosing colonies based on morphology is more efficient [54], but leads to a bias towards detecting those that are morphologically distinct such as serotype 3 or nontypeable (NT) pneumococci [57]. Select one colony from the selective plate. If more than one morphology is present, this colony should be from the predominant morphology.