Combination therapy with ampicillin and azithromycin in an experimental pneumococcal pneumonia is bactericidal and effective in down regulating inflammation in mice

Table 2 Bacterial burden in lungs and blood of mice infected with S. pneumoniae ^a and receiving either a single or a combined antibiotic treatment

Treatment	Collection of samples at different time (hours) after antibiotic administration	Total number of mice/number of bacteremic mice	CFU (Mean ± SD)
Treatment		Total number of mice/number of bacteremic mice	Lungs (per ml of tissue homogenate)	Blood (per ml)
Untreated	0	4/0	114 ± 10.26	29 ± 9.34
	1	4/0	186 ± 12.04	38 ± 8.33
	2	4/1	290 ± 8.48	134 ± 10.06
	3	5/2	356 ± 15.23	182 ± 13.65
	4	6/3	408 ± 7.36	242 ± 15.27
	5	6/4	468 ± 11.45	286 ± 10.14
	6	6/6	480 ± 5.76	307 ± 10.58
AMP alone	0	4/0	390 ± 17.43	16 ± 5.66
	1	5/0	338 ± 15.27	24 ± 5.06
	2	5/0	307 ± 10.58	42 ± 8.19
	3	5/2	286 ± 10.14	186 ± 4.58
	4	5/3	242 ± 15.27	196 ± 8.50
	5	6/3	182 ± 13.65	143 ± 9.53
	6	6/4	134 ± 10.06	111 ± 3.05
AZM alone	0	4/0	376 ± 7.05	56 ± 6.28
	1	4/0	342 ± 11.59	71 ± 11.25
	2	4/0	311 ± 14.36	83 ± 10.09
	3	4/2	262 ± 9.53	162 ± 11.59
	4	5/3	196 ± 4.58	134 ± 6.02
	5	6/2	143 ± 8.50	104 ± 7.58
	6	6/2	111 ± 3.05	95 ± 3.51
AMP + AZM combined	0	4/0	381 ± 3.51
	1	4/0	356 ± 9.60	89 ± 7.26
	2	4/1	324 ± 7.36	90 ± 12.03
	3	5/1	252 ± 4	175 ± 8.79
	4	6/1	173 ± 7.37	131 ± 6.82^*
	5	6/0	137 ± 6.02	79 ± 5.36^*
	6	6/0	99 ± 1.52	44 ± 10.15

^a5 × 10⁶ CFU/mouse; ^cSignificant difference (P < 0.05) compared with the results for untreated S. pneumoniae infected group. Mean bacterial counts in lungs and blood at 18 h post infection for mice infected with S. pneumonia (AMRI-SP-1) and after initiation of antibiotic therapy either alone or in combination. ^*Bacterial CFU counts in the AMP + AZM group are significantly lower than that of AMP or AZM alone groups at 4^th and 5^th hour post antibiotic treatment. Results for each group are given as mean ± standard deviation of five mice.

ISSN: 1476-9255