clinically significant mrsa and mssa isolates , identified during january 2006march 2008 , within 3 select communities ( sites a 
site b also included 1 adjoining community , and sites a and b also included additional first nations reserves serviced by the community .
a total of 1,280 isolates , obtained from skin and soft tissue infections ( sstis ) , urinary tract infections , upper respiratory tract infections , and lower respiratory tract infections , were identified as s. aureus . a high proportion of these isolates , 692 ( 54.1% ) of 1,280 , were mrsa . over the 2-year study period , rates of mrsa and mssa infections in the 3 communities ranged from 146482/10,000 and 112329/10,000 population , respectively .
trends of seasonality were apparent for mrsa infections , with the highest rates being observed in the third and fourth quarters of the year ( figure 1 ) .
overall , the highest quarterly rates of mrsa and mssa infections were observed at site c , with 738/10,000 and 610/10,000 population , respectively .
crude rates of community - acquired methicillin - resistant staphylococcus aureus ( a ) and methicillin - susceptible s. aureus ( b ) infections per 10,000 population in 3 select communities ( sites a , b , and c ) of northern saskatchewan , canada . the highest proportion of mrsa ( 30.4% ) and mssa ( 32.1% ) infections were identified in children < 10 years of age ( figure 2 ) .
compared to mssa infections , mrsa infections were statistically more likely to be causing infections in persons < 30 years of age ( odds ratio [ or ] 1.46 , 95% confidence interval [ ci ] 1.141.86 , p = 0.002 ) and less likely to be causing infections in patients > 60 years of age ( or 0.33 , 95% ci 0.200.567 ) , p<0.001 ) ( figure 2 ) . no significant difference was found in gender between those who acquired mrsa ( 46.7% male ) and mssa ( 53.3% female , 49.4% male ) infections .
age distribution of methicillin - resistant staphylococcus aureus ( mrsa ) and methicillin - susceptible s. aureus ( mssa ) infections in 3 select communities of northern saskatchewan , canada .
most mrsa ( 98.6% ) and mssa ( 91% ) isolates were obtained from sstis .
further analysis of sstis , comparing where on the body the infections were seen , showed significantly more mrsa infections in the axillae ( or 3.04 , 95% ci 1.396.89 , p = 0.004 ) , buttocks ( or 2.1 , 95% ci 1.273.49 , p = 0.003 ) , and trunk ( or 2.25 , 95% ci 1.543.31 , p = < 0.001 ) than mssa infections .
mrsa infections were significantly less likely to be found in feet ( or 0.29 , 95% ci 0.180.45 , p<0.001 ) , hands ( or 0.45 , 95% ci 0.30.68 , p<0.001 ) , and face or head ( or 0.66 , 95% ci 0.480.90 , p = 0.009 ) . of the additional infection sites included in this study ,
mssa infections were statistically more likely to be identified in lower respiratory tract infections ( or 5.6 , 95% ci 1.524.62 , p<0.05 ) and urinary tract infections ( or 6.76 , 95% ci 2.8716.71 , p<0.001 ) .
a subset of 665 isolates were further characterized by antimicrobial drug susceptibility testing ( table 1 ) . in comparison to mssa ,
mrsa were significantly more likely to be susceptible to clindamycin , erythromycin , fusidic acid , and gentamicin , but were more likely to be resistant to mupirocin ( table 1 ) . in regards to the clindamycin - resistant isolates , 3 ( 18.8% ) of the 16 mrsa isolates and 73 ( 93.6% ) of the 78 mssa isolates
all 328 of the mrsa isolates , but only 54 ( 70.1% ) of the 77 mssa isolates , displayed high level resistance ( > 128 g / ml ) .
mrsa , methicilllin - resistant staphylococcus aureus ; mssa , methicillin - susceptible s. aureus ; r , resistant ; or , odds ratio ; ci , confidence interval ; mic50 , 50% minimum inhibitory concentration ; mic90 , 90% inhibitory concentration ; sxt , sulfamethoxazole / trimethoprim ; ns , not significant . pulsed - field gel electrophoresis ( pfge ) showed that most mrsa isolates ( 372/379 , 98.2% ) were usa400 .
the remaining 7 mrsa isolates were identified as cmrsa10 ( usa300 , sequence type ( st ) 8) ( n = 5 ) , cmrsa2 ( usa100/800
, st5 ) ( n = 1 ) , and cmrsa8 ( emrsa15 , st22 ) ( n = 1 ) . as anticipated , pfge revealed much greater genetic diversity among the mssa strains circulating in these regions than in mrsa strains .
notably , however , most mssa pfge fingerprints ( 79.2% ) were related to highly successful canadian epidemic mrsa strains , a finding that was further confirmed by using spa typing ( 5 ) ( table 2 ) . *
mssa , methicilin - susceptible staphylococcus aureus ; mrsa , methicillin - resistant s. aureus ; pvl , panton - valentine leukocidin ; pfge , pulsed - field gel electrophoresis ; mlst , multilocus sequence typing ; st , sequence type . 
mrsa isolates were more likely to harbor the genes encoding panton - valentine leukocidin than were mssa isolates , 95.5% versus 5.2% , respectively .
the pfge and spa types of the 15 panton - valentine leukocidin  positive mssa isolates were associated with the ca - mrsa epidemic strain types usa400 , usa300 , and usa1000 ( table 2 ) .
rates of mssa and mrsa infections in these 3 northern saskatchewan communities ( 112482 cases/10,000 population ) far exceed mrsa rates reported in the neighboring provinces of manitoba ( 16/10,000 population ) ( 6 ) and alberta ( 10.7/10,000 population ) ( 7 ) , as well as benchmark hospital rates provided by the canadian nosocomial infection surveillance program ( 3.43 cases/10,000 patient days ) ( 1 ) .
the high rates of s. aureus infections in remote northern saskatchewan communities has been attributed to a combination of risk factors , including overcrowding and poor housing conditions , inadequate hygiene , preexisting skin conditions , and previous high usage of antimicrobial drugs ( 8) .
usa400 was by far the predominant strain type in all 3 communities , accounting for > 98% of the mrsa isolates .
usa400 was first reported in manitoba as an outbreak in the southern region in the late 1990s , but has since spread to the northern regions of the province from 2000 to 2004 ( 9 ) .
usa400 was thereafter seen in a central eastern saskatchewan community adjacent to the manitoba border ( 2 ) and has since disseminated as far north as nunavut ( 10 ) and southwestern alaska ( 11 ) . because mrsa and mssa sstis tended to be identified more frequently from different body sites , it is appealing to speculate that ca - mrsa strains , such as usa400 , might also colonize different body sites ( e.g. , axillae or intestines ) more efficiently than other strains of s. aureus .
this hypothesis coincides with a recent report in which nasal colonization was less likely in patients with ca - mrsa sstis than in those with hospital - acquired mrsa sstis ( 12 ) .
intestinal carriage of s. aureus has been implicated as a risk factor for infection ( 13 ) and could be a strong contributor to environmental dissemination and transmission ( 14 ) .
this possibility was recently further supported by the results of a study in which the rectal carriage , but not nasal carriage , of usa300 was strongly associated with sstis in children ( 15 ) .
further study is required to determine whether specific lineages of s. aureus are more proficient colonizers at non - nasal colonization sites , what host / bacteria genetic factors are involved , and whether this colonization plays a role in the high success of these ca - mrsa strain types . to address the high rates of s. aureus infections in northern saskatchewan , physician treatment algorithms and educational materials
these materials are all freely available ( www.narp.ca ) and are intended to promote proper antimicrobial drug usage and hygiene to diminish the spread of s. aureus disease .
 surveillance of staphylococcus aureus infections in 3 northern remote communities of saskatchewan was undertaken . 
 rates of methicillin - resistant infections were extremely high ( 146482/10,000 population ) , and most ( 98.2% ) were caused by usa400 strains . although usa400 prevalence has diminished in the united states , this strain is continuing to predominate throughout many northern communities in canada . 