Volume 12, Number 4—April 2006
Research
Contrasting Pediatric and Adult Methicillin-resistant Staphylococcus aureus Isolates
, Susan E. Crawford*, Susan Boyle-Vavra*, Mark A. Hostetler*, Daniel C. Kim*, and Robert S. Daum*
Table 3
Percentage of methicillin-resistant Staphylococcus aureus (MRSA) resistant to non–β-lactam antimicrobial drugs among pediatric and adult patients, stratified by hospital- and by community-associated designation
| In addition to methicillin,* % resistant to | Adult community-associated, % (n = 280) | Pediatric community-associated, % (n = 177) | p value† | Adult hospital-associated, % (n = 97) | Pediatric hospital-associated, % (n = 24) | p value‡ |
|---|---|---|---|---|---|---|
| No other antimicrobial drugs§ | 3.6 | 9.6 | 0.001 | 3.1 | 4.2 | 0.99 |
| Ciprofloxacin | 62.1 | 10.7 | <0.001 | 87.6 | 62.5 | 0.004 |
| Clindamycin | ||||||
| Resistant¶ | 51.8 | 7.3 | <0.001 | 74.2 | 75.0 | 0.94 |
| D-test positive# | 20.5 | 15.2 | 0.29 | 50 | 0 | 0.48 |
| Erythromycin | 93.2 | 87.0 | 0.03 | 93.8 | 95.8 | 0.99 |
| Gentamicin | 11.1 | 1.1 | <0.001 | 14.4 | 37.5 | 0.01 |
| Rifampin | 1.8 | 0 | 0.16 | 1.0 | 0 | 0.99 |
| Tetracycline** | 19.9 | 6.4 | <0.001 | 13.5 | 8.3 | 0.73 |
| TMP-SMX†† | 0 | 0 | NA | 0 | 0 | NA |
| Vancomycin | 0 | 0 | NA | 0 | 0 | NA |
| >3 non–β-lactam antimicrobial drugs | 52.3 | 6.4 | <0.001 | 76.0 | 66.7 | 0.35 |
*Methicillin resistance inferred from oxacillin resistance test.
†p value compares community-associated (CA) adult and pediatric isolates for resistance to each antimicrobial drug or test, χ2 or Fisher exact test. NA, not applicable.
‡p value compares hospital-associated (HA) MRSA adult and pediatric isolates for resistance to each antimicrobial drug or test, χ2 or Fisher exact test.
§Includes erythromycin, clindamycin, ciprofloxacin, gentamicin, rifampin, and tetracycline and does not include D-test–positive results.
¶Data in this row represent single-agent Vitek testing results for clindamycin.
#112 (97%) of the adult CA-MRSA isolates, 125 (89%) of the pediatric CA-MRSA isolates, 18 (95%) of the adult HA-MRSA isolates, and 2 (67%) of the pediatric HA-MRSA isolates that were erythromycin resistant and clindamycin susceptible by Vitek were evaluated by D-testing.
**Nine isolates not tested for susceptibility to tetracycline were omitted.
††TMP-SMX, trimethoprim-sulfamethoxazole. Only 100 adult CA-MRSA, 121 pediatric CA-MRSA, 15 adult HA-MRSA, and 2 pediatric HA-MRSA isolates that were clindamycin susceptible and erythromycin resistant were tested for TMP-SMX susceptibility.