Table 3.
Relative Risk of Mortality Among Patients With Nosocomial Pneumonia Due to Methicillin-Resistant Staphylococcus aureus (MRSA), by Isolate and Patient Characteristic
| Covariate | Patients Who Died/Patients Evaluated (%) |
RR (95% CI) | |
|---|---|---|---|
| Low Cytotoxic Activity (n = 273) | High Cytotoxic Activitya (n = 108) | ||
| Genotypic characteristic | |||
| agr group | |||
| I | 27/68 (39.7) | 13/83 (15.7) | 2.54 (1.42–4.52) |
| II | |||
| No (groups I, III) | 27/76 (35.5) | 13/83 (15.7) | 2.27 (1.27–4.07) |
| Yes | 58/196 (29.6) | 1/25 (4.0) | 7.40 (1.07–51.09) |
| III | 0/8 (0.0) | 0/0 (NA) | … |
| NT | 0/1 (0.0) | 0/0 (NA) | … |
| SCCmec type | |||
| I, II, III | 75/243 (30.9) | 1/20 (5.0) | 6.17 (.91–42.09) |
| IV | 10/30 (33.3) | 13/88 (14.8) | 2.26 (1.11–4.60) |
| Clonal complex | |||
| 5 | |||
| No | 27/76 (35.5) | 13/84 (15.5) | 2.30 (1.28–4.12) |
| Yes | 58/197 (29.4) | 1/24 (4.2) | 7.07 (1.02–48.72) |
| 8 | |||
| No | 77/256 (30.1) | 3/39 (7.7) | 3.91 (1.30–11.78) |
| Yes | 8/17 (47.1) | 11/69 (15.9) | 2.95 (1.41–6.19) |
| 22 | |||
| No | 85/272 (31.3) | 14/101 (13.9) | 2.25 (1.34–3.78) |
| Yes | 0/1 (0.0) | 0/7 (0.0) | … |
| 45 | 2/13 (15.4) | 0/0 (NA) | … |
| No | 83/260 (31.9) | 14/108 (13.0) | 2.46 (1.46–4.14) |
| Yes | 2/13 (15.4) | 0/0 (NA) | … |
| 8/239 | 17/34 (50.0) | 1/4 (25.0) | 2.00 (.35–11.29) |
| No | 68/239 (28.5) | 13/104 (12.5) | 2.28 (1.32–3.93) |
| Yes | 17/34 (50.0) | 1/4 (25.0) | 2.00 (.35–11.29) |
| Other | 0/11 (0.0) | 1/4 (25.0) | … |
| spa type 2 | |||
| 2 | 35/112 (31.3) | 0/11 (0.0) | … |
| Other | 50/161 (31.1) | 14/97 (14.4) | 2.15 (1.26–3.68) |
| pvl | |||
| No | 81/264 (30.7) | 7/69 (10.1) | 3.02 (1.46–6.25) |
| Yes | 4/9 (44.4) | 7/39 (17.9) | 2.48 (.92–6.68) |
| Phenotypic characteristic | |||
| agr functionalityb | |||
| 0 | 13/61 (21.3) | 0/0 (NA) | … |
| 1 | 26/68 (38.2) | 1/4 (25.0) | 1.53 (.27–8.58) |
| 2 | 46/144 (31.9) | 13/104 (12.5) | 2.56 (1.46–4.48) |
| 0, 1 | 39/129 (30.2) | 1/4 (25.0) | 1.21 (.22–6.74) |
| 1, 2 | 72/212 (34.0) | 14/108 (13.0) | 2.62 (1.55–4.42) |
| Vancomycin susceptibility | |||
| Heteroresistant | 16/56 (28.6) | 0/4 (0.0) | … |
| Susceptible | 69/217 (31.8) | 14/104 (13.5) | 2.36 (1.40–3.99) |
| Vancomycin MIC, μg/mL | |||
| By the Etest | |||
| ≤1 | |||
| Yes | 7/32 (21.9) | 0/12 (0.0) | … |
| No | 78/241 (32.4) | 14/96 (14.6) | 2.22 (1.32–3.72) |
| ≤1.5 | |||
| Yes | 63/174 (36.2) | 10/86 (11.6) | 3.11 (1.68–5.76) |
| No | 22/99 (22.2) | 4/22 (18.2) | 1.22 (.47–3.19) |
| By an automated method | |||
| 0.5 | 1/14 (7.1) | 0/15 (0.0) | … |
| 1 | 75/231 (32.5) | 12/87 (13.8) | 2.35 (1.35–4.11) |
| ≥2 | 9/27 (33.3) | 2/6 (33.3) | 1.00 (.29–3.49) |
| Linezolid MIC, by the Etest | |||
| 1 | 4/14 (28.6) | 2/9 (22.2) | 1.29 (.29–5.63) |
| 2 | 62/188 (33.0) | 9/80 (11.3) | 2.93 (1.53–5.61) |
| 4 | 19/70 (27.1) | 3/16 (18.8) | 1.45 (.49–4.30) |
| Demographic/clinical characteristic | |||
| Age, y | |||
| ≤65 | 26/128 (20.3) | 5/62 (8.1) | 2.52 (1.02–6.24) |
| >65 | 59/145 (40.7) | 9/46 (19.6) | 2.08 (1.12–3.86) |
| Sex | |||
| Female | 36/106 (34.0) | 4/32 (12.5) | 2.72 (1.05–7.06) |
| Male | 49/167 (29.3) | 10/76 (13.2) | 2.23 (1.20–4.16) |
| Race | |||
| Asian | 10/48 (20.8) | 1/11 (9.1) | 2.29 (.33–16.08) |
| Black | 9/26 (34.6) | 3/21 (14.3) | 2.42 (.75–7.83) |
| White | |||
| No | 22/89 (24.7) | 4/33 (12.1) | 2.04 (.76–5.48) |
| Yes | 63/184 (34.2) | 10/75 (13.3) | 2.57 (1.39–4.73) |
| Other | 3/15 (20.0) | 0/1 (0.0) | … |
| Region | |||
| Asia | 9/43 (20.9) | 1/8 (12.5) | 1.67 (.24–11.46) |
| Europe | 3/17 (17.6) | 2/19 (10.5) | 1.68 (.32–8.86) |
| Latin America | 16/31 (51.6) | 1/5 (20.0) | 2.58 (.43–15.39) |
| Other | 5/10 (50.0) | 1/7 (14.3) | 3.50 (.51–23.81) |
| United States | |||
| Yes | 52/172 (30.2) | 9/69 (13.0) | 2.32 (1.21–4.44) |
| No | 33/101 (32.7) | 5/39 (12.8) | 2.55 (1.07–6.05) |
| Treatment | |||
| Linezolid | 44/136 (32.4) | 8/53 (15.1) | 2.14 (1.08–4.24) |
| Vancomycin | 41/137 (29.9) | 6/55 (10.9) | 2.74 (1.24–6.09) |
| APACHE score | |||
| ≤20 | 42/186 (22.6) | 6/74 (8.1) | 2.78 (1.24–6.27) |
| >20 | 42/85 (49.4) | 8/31 (25.8) | 1.91 (1.02–3.61) |
| Missing | 1/2 (50.0) | 0/3 (0.0) | |
| ICU stay at baseline | |||
| No | 9/36 (25.0) | 1/13 (7.7) | 3.25 (.45–23.22) |
| Yes | 76/237 (32.1) | 13/95 (13.7) | 2.34 (1.37–4.01) |
| Vasopressor therapy at baseline | |||
| No | 64/228 (28.1) | 9/89 (10.1) | 2.78 (1.44–5.33) |
| Yes | 21/45 (46.7) | 5/19 (26.3) | 1.77 (.79–4.00) |
| Corticosteriod therapy at baseline | |||
| No | 61/210 (29.0) | 10/89 (11.2) | 2.59 (1.39–4.81) |
| Yes | 24/63 (38.1) | 4/19 (21.1) | 1.81 (.72–4.57) |
| Bacteremia | |||
| No | 68/237 (28.7) | 11/93 (11.8) | 2.43 (1.34–4.38) |
| Yes | 17/36 (47.2) | 3/15 (20.0) | 2.36 (.81–6.88) |
| Chest radiography finding | |||
| Bilateral | 64/190 (33.7) | 11/69 (15.9) | 2.11 (1.19–3.76) |
| Unilateral | 21/83 (25.3) | 3/38 (7.9) | 3.20 (1.02–10.09) |
| Missing | 0/0 (NA) | 0/1 (0.0) | |
| Pleural effusion | |||
| No | 48/140 (34.3) | 9/70 (12.9) | 2.67 (1.39–5.12) |
| Yes | 37/133 (27.8) | 5/38 (13.2) | 2.11 (.89–5.00) |
| Pneumonia, by type | |||
| Hospital associated | 17/78 (21.8%) | 2/21 (9.5%) | 2.29 (.57–9.13) |
| Healthcare associated | 17/51 (33.3%) | 1/10 (10.0%) | 3.33 (.50–22.27) |
| Ventilator associated | 51/144 (35.4%) | 11/77 (14.3%) | 2.48 (1.37–4.47) |
| Ventilation at baseline | |||
| No | 20/83 (24.1) | 1/25 (4.0) | 6.02 (.85–42.68) |
| Yes | 65/190 (34.2) | 13/83 (15.7) | 2.18 (1.28–3.74) |
| Infecting pathogen(s) | |||
| MRSA + anaerobe | 0/2 (0.0) | 0/0 (NA) | … |
| MRSA + fungus | 5/10 (50.0) | 0/1 (0.0) | … |
| MRSA + gram negative | 20/66 (30.3) | 4/33 (12.1) | 2.50 (.93–6.72) |
| MRSA + gram positive | 6/21 (28.6) | 0/10 (0.0) | … |
| MRSA + gram positive + gram negative | 5/15 (33.3) | 1/5 (20.0) | 1.67 (.25–11.07) |
| MRSA only | 49/159 (30.8) | 9/59 (15.3) | 2.02 (1.06–3.85) |
| MRSA + other | 36/114 (31.6) | 5/49 (10.2) | 3.09 (1.29–7.41) |
| Anaerobic coverage at baseline | |||
| No | 35/125 (28.0) | 4/44 (9.1) | 3.08 (1.16–8.17) |
| Yes | 50/148 (33.8) | 10/64 (15.6) | 2.16 (1.17–3.99) |
| Gram-negative coverage at baseline | |||
| No | 1/4 (25.0) | 0/3 (0.0) | … |
| Yes | 84/269 (31.2) | 14/105 (13.3) | 2.34 (1.39–3.93) |
| Service | |||
| Medical | |||
| Yes | 55/162 (34.0) | 9/49 (18.4) | 1.85 (.99–3.46) |
| No | 30/111 (27.0) | 5/59 (8.5) | 3.19 (1.31–7.79) |
| Surgical | 20/68 (29.4) | 3/24 (12.5) | 2.35 (.77–7.22) |
| Trauma | 10/43 (23.3) | 2/35 (5.7) | 4.07 (.95–17.37) |
| Comorbidity | |||
| Cardiac | |||
| No | 23/98 (23.5) | 5/54 (9.3) | 2.53 (1.02–6.29) |
| Yes | 62/175 (35.4) | 9/54 (16.7) | 2.13 (1.13–3.99) |
| Diabetes | |||
| No | 41/152 (27.0) | 10/79 (12.7) | 2.13 (1.13–4.02) |
| Yes | 44/121 (36.4) | 4/29 (13.8) | 2.64 (1.03–6.75) |
| Neoplastic | |||
| No | 73/244 (29.9) | 10/96 (10.4) | 2.87 (1.55–5.32) |
| Yes | 12/29 (41.4) | 4/12 (33.3) | 1.24 (.50–3.08) |
| Renal/urinary | |||
| No | 37/149 (24.8) | 10/78 (12.8) | 1.94 (1.02–3.68) |
| Yes | 48/124 (38.7) | 4/30 (13.3) | 2.90 (1.14–7.42) |
| Pulmonary | |||
| No | 22/86 (25.6) | 5/34 (14.7) | 1.74 (.72–4.22) |
| Yes | 63/187 (33.7) | 9/74 (12.2) | 2.77 (1.45–5.28) |
| Hepatobiliary | |||
| No | 72/232 (31.0) | 9/95 (9.5) | 3.28 (1.71–6.28) |
| Yes | 13/41 (31.7) | 5/13 (38.5) | 0.82 (.36–1.87) |
| Gastrointestinal | |||
| No | 24/116 (20.7) | 5/47 (10.6) | 1.94 (.79–4.79) |
| Yes | 61/157 (38.9) | 9/61 (14.8) | 2.63 (1.40–4.97) |
| LTCF stay at baseline | |||
| No | 82/261 (31.4) | 13/104 (12.5) | 2.51 (1.47–4.31) |
| Yes | 3/12 (25.0) | 1/4 (25.0) | 1.00 (.14–7.10) |
Data associated with creatinine clearance and Clinical Pulmonary Infection Score are not shown.
Abbreviations: APACHE, Acute Physiology and Chronic Health Evaluation; CI, confidence interval; LTCF, long-term care facility; MIC, minimum inhibitory concentration; NA, not applicable; NT, not typable; RR, relative risk; SCCmec, staphylococcal cassette chromosome mec.
a Defined as a mean of ≥90% killing of PMN-HL60 cells within 2 hours.
b Semiquantitative scoring of δ-hemolysin on sheep blood agar: 0, nonhemoltyic; 1, weakly hemolytic; 2, strongly hemolytic.