Potential Associations between Hematogenous Complications and Bacterial Genotype inStaphylococcus aureusInfection

Abstract

Background. The impact of bacterial clonality on infections caused byStaphylococcus aureus is unclear. Methods. Three hundred seventy-nine S. aureus isolates (125 methicillin-resistant S. aureus [MRSA] and 254 methicillin-susceptible S. aureus [MSSA]) were genotyped by spa typing and multilocus sequence typing. For MRSA isolates, the staphylococcal chromosomal cassette mec (SCCmec) element was also typed. Three clinical categories were identified: nasal carriage only ( ), uncomplicated infection ( ), and bacteremia with hematogn p 118 n p 104 enous complications ( ). n p 157 Results. By use of eBURST, 18 clonal complexes (CCs) were found in 371 isolates. Eight CCs accounted for 89% of isolates and occurred in all clinical categories. CC5 () and CC30 ( ) exhibited a significant P p .0025 P p .0308 trend toward more frequent hematogenous complications. Isolates within spa types 2 and 16 showed the same significant trend and grouped within CC5 and CC30, respectively. SCCmec II isolates also showed the same significant trend compared with SCCmec IV; 96% were CC5 or CC30.Conclusions. Although most S. aureus genotypes exhibited the capacity to cause invasive disease, strains within CC5 and CC30 exhibited a significant trend toward increasing levels of hematogenous complications. Isolates within these CCs were also implicated by use of spa and SCCmec typing. The genetic determinants underlying these findings remain to be demonstrated.

Molecular differentiation of historic phage-type 80/81 and contemporary epidemic Staphylococcus aureus

“…4). For example, Fowler et al reported that EMRSA-16 and related isolates (ST36) were significantly associated with increased severity of infection (15). These findings seem at variance with our mouse infection data, but it is important to note that the infections caused by these CC30 strains occurred in the healthcare setting, and as such, infected individuals had underlying risk factors for infection (13,15).…”

“…For example, Fowler et al reported that EMRSA-16 and related isolates (ST36) were significantly associated with increased severity of infection (15). These findings seem at variance with our mouse infection data, but it is important to note that the infections caused by these CC30 strains occurred in the healthcare setting, and as such, infected individuals had underlying risk factors for infection (13,15). Further, S. aureus strains with defective Agr gene regulatory systems (such as the contemporary CC30 hospital isolates studied here) typically have increased levels of surface protein expression, such as protein A and EMRSA-16, and related CC30 MSSA clones are known to be prominent human nasal colonizers (13,15).…”

“…One of the most successful MRSA clones over the past 20 y is known as epidemic MRSA-16 (EMRSA-16), which was first reported in the United Kingdom in 1992 (13). EMRSA-16 spread to hospitals in Europe (13,14) and the United States (15)(16)(17), and there is also relatively high prevalence of hospital infections caused by methicillin-susceptible S. aureus (MSSA) strains related to EMRSA-16 by multilocus sequence type (MLST), which is used to determine whether strains belong to the same clonal complex (15,18). It is notable that phage-type 80/81 S. aureus and EMRSA-16 belong to the same clonal complex 30 (CC30) and may have a recent common ancestor (19).…”

Recent human-to-poultry host jump, adaptation, and pandemic spread of Staphylococcus aureus

“…The increase in prevalence of skeletal infections of poultry to become a major cause of lameness in the industry correlates with the emergence and wide dissemination of the ST5 poultry subtype. Of note, a previous study reported that the ST5 clonal complex is associated with increased frequency of hematogenous infections of humans, including osteomyelitis (26), consistent with the largely skeletal tropism of infections caused by the poultry ST5 clade. The reduction in the biodiversity of chickens in the broiler poultry industry such that a very small number of breeding lines are supplied for global consumption promotes the spread of opportunistic pathogens that are resident on those birds and could select for infectious diseases to which those animals are genetically predisposed.…”

Reemergence of antibiotic-resistant Staphylococcus aureus in the genomics era

“…In contrast, Fridkin and colleagues found that 77% of CA-MRSA infections were of skin and soft tissue (mainly abscesses and cellulitis), with only 6% causing invasive disease (16). In the United States, USA100, USA200, and USA500 constitute the most abundant isolates from health care-associated infections, whereas USA300 and USA400 account for the greatest number of CA-MRSA isolates (11,17,23,47,86). These differences in invasive disease and mortality for health care-associated MRSA versus CA-MRSA infections could suggest that health care-associated strains are more virulent than those causing community infections.…”