Table 1.
S. aureus growth rates vs. health and treatment indicators
| Clinical parameter | Samples | Data range | Statistic† | P value | Significance |
| Age | 37 | 9–20 y of age | Spearman (−0.23) | 0.2 | — |
| Sex | 37 | female (8), male (29) | MWW (female > male) | 0.3 | — |
| Race | 37 | Hispanic (21), Non-Hispanic White (11), African-American (5) | Spearman (−0.23) | 0.2 | — |
| BMI | 33 | 14.1–21.3 kg/m2 | Spearman (0.18) | 0.3 | — |
| FEV1% | 37 | 20–118% predicted | Spearman (0.06) | 0.7 | — |
| Pulmonary exacerbation | 37 | no (20), yes (17) | MWW (no > yes) | 0.004 | ** |
| Hospital day | 15 | day 1–30 | Spearman (0.53) | 0.04 | * |
| P. aeruginosa present‡ | 32 | no (21), yes (11) | MWW (no > yes) | 0.1 | — |
| Staphylococcacea‡ | 32 | 40–71% | Spearman (−0.12) | 0.5 | — |
| Vancomycin§ | 37 | treatment at the time included this antibiotic: no (32), yes (5) | MWW (no > yes) | 0.002 | ** |
| Piperacillin/tazobactam§ | 37 | treatment at the time included this antibiotic: no (30), yes (7) | MWW (no > yes) | 0.003 | ** |
| Tobramycin§ | 36 | treatment at the time included this antibiotic: no (11), yes (25) | MWW (no > yes) | 0.05 | * |
| Inhaled aztreonam§ | 36 | treatment at the time included this antibiotic: no (27), yes (9) | MWW (no > yes) | 0.1 | — |
| Colistin§ | 36 | treatment at the time included this antibiotic: no (27), yes (9) | MWW (no > yes) | 0.1 | — |
| Moxifloxacin§ | 36 | treatment at the time included this antibiotic: no (31), yes (5) | MWW (no > yes) | 0.3 | — |
Summary of statistical relationships between S. aureus average population growth rate and different health and treatment indicators by Mann−Whitney−Wilcoxon (MWW) test (for binary parameters) or Spearman rank analysis. Spearman’s P < 0 indicates positive correlation (i.e., faster growth rate with increase of the clinical parameter), and P < 0 indicates a negative correlation. See Table S1 for all data, and see Figs. S7 and S8 for correlation plots. Only antibiotics with at least five samples in each category (yes/no) were analyzed. —P > 0.05, *P ≤ 0.05, **P ≤ 0.01.
Evaluated by MWW test for binary parameters (sex, pulmonary exacerbation, and P. aeruginosa presence; each was evaluated for both alternative hypotheses; the most statistically significant alternative is given) and by Spearman rank analysis for all other parameters.
The presence of P. aeruginosa was tested in routine clinical selective plating screens. The abundance of Staphylococcaceae was assessed by 16S rRNA gene sequencing.
Vancomycin is used against Gram-positive pathogens including MRSA; piperacillin/tazobactam is used against P. aeruginosa and some S. aureus (not effective against MRSA); tobramycin, aztreonam, and colistin are mostly used against P. aeruginosa; moxifloxacin is a broad-spectrum antibiotic mostly used against mycobacteria.