Experimental infection of human erythrocytes from alcoholic patients with Bartonella quintana

Bartonella spp. are found in the erythrocytes of their specific natural hosts and B. quintana bacteremia is associated epidemiologically with lice, alcoholism, and homelessness. The aim of our study was to compare the growth and the number of bacteria per erythrocyte in vitro in laboratory-infected red blood cells from alcoholic patients versus normal blood donor erythrocytes. Enumeration of bacteria was performed either with plate counting or with a real-time PCR quantitative assay. Number of bacteria per cell was determined using immunofluorescence assay and laser confocal microscopy. Although the number of bacteria after 4 days of incubation was similar in the two groups of erythrocytes, we found that the distribution of bacteria per erythrocyte in the two groups was different. Erythrocytes from alcoholics contain significantly more bacteria per cell than erythrocytes from blood donors. Our results suggest that there is a link between alcoholism and infections of B. quintana that may be due to the macrocytosis of erythrocytes.