CA-MRSA Accounts for 66% of MRSA Infections

Major Finding: U.S. hospital discharges for CA-MRSA over a 10-year period went up eightfold, from 0.4 per 1,000 to 3.3 per 1,000.

Data Source: An analysis of 824,307 S. aureus isolates obtained in 1998–2007 in The Surveillance Network database and National Hospitalization Discharge Survey data.

Disclosures: GlaxoSmithKline supported the study. Dr. Mera is an employee of GlaxoSmithKline.

VIENNA — Community-acquired MRSA as a proportion of all MRSA infections tripled in a recent 10-year period, according to a large national study.

This rise in community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has occurred across all age groups, in all types of S. aureus infections, all geographic regions of the country, and in both inpatient and outpatient settings, Dr. Robertino M. Mera reported.

At the hospital level, the incidence of CA-MRSA has increased faster than hospital-acquired MRSA (HA-MRSA). The rate of hospital discharges for HA-MRSA infections has gone from 3.2 per 1,000 discharges in 1998 to 4.8 per 1,000 in 2007, a modest albeit statistically significant increase. Meanwhile, the rate of discharges for CA-MRSA has shot up eightfold, from 0.4 per 1,000 to 3.3 per 1,000.

The biggest changes in CA-MRSA trends, however, have occurred in children and in skin and soft tissue infections. While CA-MRSA accounted for less than 5% of all S. aureus infections in children under age 15 years in 1998, the proportion jumped to 45% a decade later. By 2007, 82% of all MRSA infections in children under age 15 years had the CA-MRSA phenotype. “This is quite remarkably high,” observed Dr. Mera of GlaxoSmithKline, Durham, N.C.

Moreover, 86% of all MRSA isolates obtained from abscesses in 2007 were CA-MRSA, as were 75% of those from wounds. CA-MRSA has replaced hospital-acquired MRSA as the source of most skin and soft tissue hospital infections.

In contrast, by 2007 CA-MRSA accounted for 30% of all MRSA sputum samples and 44% of blood samples.

Dr. Mera presented an analysis of 824,307 S. aureus isolates obtained from across the country in 1998–2007. The analysis utilized The Surveillance Network (TSN) database and National Hospital Discharge Survey data.

In 1998, MRSA accounted for 33% of all S. aureus infections. This proportion climbed steadily during the following decade, reaching 54% in 2007. Meanwhile, the proportion of CA-MRSA jumped from 22% in 1998 to 66% of all MRSA infections in 2007.

In 1998 there were large age-group differences in the proportion of S. aureus infections due to MRSA. Among patients older than 65 the figure was 47%, while in children younger than 15 years it was just 13%. By 2007, however, MRSA accounted for fully 47% of all S. aureus infections in children and 57% in the elderly. Among patients aged 16–44 years, the proportion of S. aureus infections due to MRSA climbed from 23% to 55% during the decade.

The CA-MRSA phenotype is defined by co-resistance to ciprofloxacin/clindamycin/erythromycin and/or nonsusceptibility to gentamicin and cotrimoxazole, the physician explained.

In 1998, CA-MRSA accounted for a mere 7.3% of all S. aureus isolates. By 2007, this figure rose to 35.6%. CA-MRSA replaced HA-MRSA and methicillin-susceptible S. aureus, which accounted for 67% of all S. aureus infections in 1998 but only 46% a decade later.

By 2007, 82% of all MRSA infections in children under age 15 years had the CA-MRSA phenotype.

Source DR. MERA

Major Finding: U.S. hospital discharges for CA-MRSA over a 10-year period went up eightfold, from 0.4 per 1,000 to 3.3 per 1,000.

Data Source: An analysis of 824,307 S. aureus isolates obtained in 1998–2007 in The Surveillance Network database and National Hospitalization Discharge Survey data.

Disclosures: GlaxoSmithKline supported the study. Dr. Mera is an employee of GlaxoSmithKline.

VIENNA — Community-acquired MRSA as a proportion of all MRSA infections tripled in a recent 10-year period, according to a large national study.

This rise in community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has occurred across all age groups, in all types of S. aureus infections, all geographic regions of the country, and in both inpatient and outpatient settings, Dr. Robertino M. Mera reported.

At the hospital level, the incidence of CA-MRSA has increased faster than hospital-acquired MRSA (HA-MRSA). The rate of hospital discharges for HA-MRSA infections has gone from 3.2 per 1,000 discharges in 1998 to 4.8 per 1,000 in 2007, a modest albeit statistically significant increase. Meanwhile, the rate of discharges for CA-MRSA has shot up eightfold, from 0.4 per 1,000 to 3.3 per 1,000.

The biggest changes in CA-MRSA trends, however, have occurred in children and in skin and soft tissue infections. While CA-MRSA accounted for less than 5% of all S. aureus infections in children under age 15 years in 1998, the proportion jumped to 45% a decade later. By 2007, 82% of all MRSA infections in children under age 15 years had the CA-MRSA phenotype. “This is quite remarkably high,” observed Dr. Mera of GlaxoSmithKline, Durham, N.C.

Moreover, 86% of all MRSA isolates obtained from abscesses in 2007 were CA-MRSA, as were 75% of those from wounds. CA-MRSA has replaced hospital-acquired MRSA as the source of most skin and soft tissue hospital infections.

In contrast, by 2007 CA-MRSA accounted for 30% of all MRSA sputum samples and 44% of blood samples.

Dr. Mera presented an analysis of 824,307 S. aureus isolates obtained from across the country in 1998–2007. The analysis utilized The Surveillance Network (TSN) database and National Hospital Discharge Survey data.

In 1998, MRSA accounted for 33% of all S. aureus infections. This proportion climbed steadily during the following decade, reaching 54% in 2007. Meanwhile, the proportion of CA-MRSA jumped from 22% in 1998 to 66% of all MRSA infections in 2007.

In 1998 there were large age-group differences in the proportion of S. aureus infections due to MRSA. Among patients older than 65 the figure was 47%, while in children younger than 15 years it was just 13%. By 2007, however, MRSA accounted for fully 47% of all S. aureus infections in children and 57% in the elderly. Among patients aged 16–44 years, the proportion of S. aureus infections due to MRSA climbed from 23% to 55% during the decade.

The CA-MRSA phenotype is defined by co-resistance to ciprofloxacin/clindamycin/erythromycin and/or nonsusceptibility to gentamicin and cotrimoxazole, the physician explained.

In 1998, CA-MRSA accounted for a mere 7.3% of all S. aureus isolates. By 2007, this figure rose to 35.6%. CA-MRSA replaced HA-MRSA and methicillin-susceptible S. aureus, which accounted for 67% of all S. aureus infections in 1998 but only 46% a decade later.

By 2007, 82% of all MRSA infections in children under age 15 years had the CA-MRSA phenotype.

Source DR. MERA

Major Finding: U.S. hospital discharges for CA-MRSA over a 10-year period went up eightfold, from 0.4 per 1,000 to 3.3 per 1,000.

Data Source: An analysis of 824,307 S. aureus isolates obtained in 1998–2007 in The Surveillance Network database and National Hospitalization Discharge Survey data.

Disclosures: GlaxoSmithKline supported the study. Dr. Mera is an employee of GlaxoSmithKline.

VIENNA — Community-acquired MRSA as a proportion of all MRSA infections tripled in a recent 10-year period, according to a large national study.

This rise in community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has occurred across all age groups, in all types of S. aureus infections, all geographic regions of the country, and in both inpatient and outpatient settings, Dr. Robertino M. Mera reported.

At the hospital level, the incidence of CA-MRSA has increased faster than hospital-acquired MRSA (HA-MRSA). The rate of hospital discharges for HA-MRSA infections has gone from 3.2 per 1,000 discharges in 1998 to 4.8 per 1,000 in 2007, a modest albeit statistically significant increase. Meanwhile, the rate of discharges for CA-MRSA has shot up eightfold, from 0.4 per 1,000 to 3.3 per 1,000.

The biggest changes in CA-MRSA trends, however, have occurred in children and in skin and soft tissue infections. While CA-MRSA accounted for less than 5% of all S. aureus infections in children under age 15 years in 1998, the proportion jumped to 45% a decade later. By 2007, 82% of all MRSA infections in children under age 15 years had the CA-MRSA phenotype. “This is quite remarkably high,” observed Dr. Mera of GlaxoSmithKline, Durham, N.C.

Moreover, 86% of all MRSA isolates obtained from abscesses in 2007 were CA-MRSA, as were 75% of those from wounds. CA-MRSA has replaced hospital-acquired MRSA as the source of most skin and soft tissue hospital infections.

In contrast, by 2007 CA-MRSA accounted for 30% of all MRSA sputum samples and 44% of blood samples.

Dr. Mera presented an analysis of 824,307 S. aureus isolates obtained from across the country in 1998–2007. The analysis utilized The Surveillance Network (TSN) database and National Hospital Discharge Survey data.

In 1998, MRSA accounted for 33% of all S. aureus infections. This proportion climbed steadily during the following decade, reaching 54% in 2007. Meanwhile, the proportion of CA-MRSA jumped from 22% in 1998 to 66% of all MRSA infections in 2007.

In 1998 there were large age-group differences in the proportion of S. aureus infections due to MRSA. Among patients older than 65 the figure was 47%, while in children younger than 15 years it was just 13%. By 2007, however, MRSA accounted for fully 47% of all S. aureus infections in children and 57% in the elderly. Among patients aged 16–44 years, the proportion of S. aureus infections due to MRSA climbed from 23% to 55% during the decade.

The CA-MRSA phenotype is defined by co-resistance to ciprofloxacin/clindamycin/erythromycin and/or nonsusceptibility to gentamicin and cotrimoxazole, the physician explained.

In 1998, CA-MRSA accounted for a mere 7.3% of all S. aureus isolates. By 2007, this figure rose to 35.6%. CA-MRSA replaced HA-MRSA and methicillin-susceptible S. aureus, which accounted for 67% of all S. aureus infections in 1998 but only 46% a decade later.

By 2007, 82% of all MRSA infections in children under age 15 years had the CA-MRSA phenotype.

Source DR. MERA