Table 3.
Epidemiologic Factors Associated With Colonization With USA500 Methicillin-Resistant Staphylococcus aureus
| Epidemiologic Factora | Number (%) of Individuals Colonized With USA500 (n = 13)b | Number (%) of Individuals Colonized With USA300 or ST5 (n = 126) | Odds Ratio | 95% Confidence Interval | P Value |
|---|---|---|---|---|---|
| White (vs non-Hispanic white and black) | 4 (30.8%) | 10 (7.9%) | 5.2 | 1.3, 19.8 | .03 |
| Hispanic (vs non-Hispanic white and black) | 1 (7.7%) | 8 (6.3%) | 1.2 | .1, 10.7 | .6 |
| Black (vs white and non-Hispanic white) | 8 (61.5%) | 108 (85.7%) | 0.3 | .1, .9 | .04 |
| Methamphetamine use | 10 (76.9%) | 24 (19%) | 14.2 | 3.6, 55.5 | <.001 |
| Ecstasy or psychedelic use | 7 (53.8%) | 56 (44.4%) | 1.5 | .5, 4.6 | .57 |
| Illicit inhalant use | 2 (15.4%) | 9 (7.1%) | 2.4 | .5, 12.3 | .27 |
| Marijuana use | 12 (92.3%) | 111 (88.1%) | 1.6 | .2, 13.4 | 1 |
| Cocaine use | 7 (53.8%) | 70 (55.6%) | 1 | .3, 2.9 | 1 |
| Heroin use | 0 | 43 (34.1%) | … | … | .01 |
| Other narcotics (eg, codeine, oxycontin) | 2 (15.4%) | 28 (22.2%) | 0.6 | .1, 3 | .73 |
| Illicit benzodiazepine use | 3 (23.1%) | 32 (25.4%) | 0.9 | .2, 3.4 | 1 |
| Taking prescription drugs to get high | 1 (7.7%) | 16 (12.7%) | 0.6 | .1, 4.7 | 1 |
| Injection drug use in the past year | 5 (38.5%) | 17 (13.5%) | 4 | 1.2, 13.7 | .03 |
| Men who have sex with men | 12 (92.3%) | 33 (26.2%) | 33.8 | 4.2, 270 | <.001 |
| Living with human immunodeficiency virus | 13 (100%) | 77 (61.1%) | … | … | <.01 |
| Previous incarceration in jail | 11 (84.6%) | 120 (95.2%) | 0.3 | .05, 1.5 | .16 |
| Release from jail in the prior 3 months | 0 | 23 (18.3%) | … | … | .13 |
| Release from jail in the prior 6 months | 2 (15.4%) | 37 (29.4%) | 0.4 | .1, 2.1 | .35 |
| Previous incarceration in prison | 0 | 85 (67.5%) | … | … | <.001 |
| Homeless or unstable housing in the past year | 6 (46.2%) | 72 (57.1%) | 0.6 | .2, 2 | .56 |
| Current skin infection | 0 | 12 (9.5%) | … | … | .6 |
| Emergency room visit in the past year | 8 (61.5%) | 71 (56.3%) | 1.2 | .4, 4 | .78 |
| Skin or methicillin-resistant Staphylococcus aureus infection in the past year | 2 (15.4%) | 14 (11.1%) | 1.5 | .3, 7.2 | .65 |
| Hospitalized in the past year | 4 (30.8%) | 38 (30.2%) | 1 | .3, 3.5 | 1 |
Eleven individuals had methicillin-resistant Staphylococcus aureus strains that were not categorized as USA500, USA300, or ST5. Of the 126 non-USA500 isolates, 101 were USA300 and 25 were ST5. All 13 individuals colonized with USA500 strains were living with human immunodeficiency virus; therefore no odds ratio could be calculated. No individuals colonized with USA500 strains had the following epidemiologic factors: heroin use, release from jail in the prior 3 months, previous incarceration in prison, or current skin infection and therefore no odds ratio could be calculated.
aAll 13 individuals colonized with USA500 strains were living with human immunodeficiency virus; therefore no odds ratio could be calculated. No individuals colonized with USA500 strains had the following epidemiologic factors: heroin use, release from jail in the prior 3 months, previous incarceration in prison, or current skin infection.
bGiven our phylogenetic analysis, we wanted to further investigate predictors of USA500 and therefore conducted a 2 × 2 analysis of this category compared to the other 2 categories combined. Results of the 2 × 3 analyses are included in Supplementary Table 2.