Blood culture collection technique and pneumococcal surveillance in Malawi during the four year period 2003–2006: an observational study

Table 2 Geometric mean blood volume cultured in relation to isolate recovery for 760 blood cultures assessed during the two surveillance periods in 2003 and 2005

	N	Mean volume ml	95% CI	OR (95%CI)	OR^a (95%CI)
No growth	566	5.51	5.28–5.75
Contaminants	52	3.76	3.17–4.45
*S. pneumoniae*	31	6.71	5.69–7.93	1.18 (1.05–1.33)	1.29 (1.08–1.53)
Non typhi *Salmonella*	70	5.21	4.61–5.87	0.99 (0.90–1.07)	0.97 (0.86–1.09)
*Cryptococcus neoformans*	4	6.72	2.45–18.45	1.19 (0.86–1.65)	0.86 (0.61–1.20)
Other Gram negative	27	3.04	1.99–4.65
Other Gram positive	10	3.70	2.63–5.20

For clarity, Gram negative and Gram positive bacteria other than S. pneumoniae and the non-typhi Salmonella have been grouped together. Odds Ratios are presented unadjusted (OR) and adjusted (OR^a) for year of sampling and represent the chances of recovering an isolate with each extra ml of blood over the range of volumes taken in this study 1–13 mls.

ISSN: 1471-2334