Broj1.anubih.ba

Methicillin-resistant Staphylococcus aureus (MRSA) in the
community – laboratory based study
Selma Uzunović-Kamberović1, Suad Sivić2 Objective To determine the occurrence and antibiotic resis-
Microbiology, 2 Department of social medicine, tance of community-acquired methicillin-resistant Staphylo- Cantonal Public Health Institution Zenica, coccus aureus (MRSA) isolates. Methods used In 2003-2005,
consecutive samples of nasal, throat, eye, ear and genitouri- nary tract s�abs, s�abs of �ound infections and soft and skin tissue infections and samples of sputum obtained from out- patients submitted to the Laboratory �ith clinical indications �ere analyzed for the presence of Staphylococcus aureus. The disc diffusion method using Mueller-Hinton agar (Oxoid, Besingstoke, UK) �as used to test against nine antimicrobi- als. Oxacillin-resistance �as confirmed by E-test (AB Biodisc, Solna, S�eden). Results A total of 1583 (11.3%) nonduplicate
S. aureus isolated from 13 937 samples. MRSA �as detected in 63 (4.1%) of S. aureus isolates. MRSA isolates more fre- quently from infected genitourinary tract and �ounds than other sites (p<0.0001). The patients in both age groups ≥65 and 0-6 years of age �ere more frequently infected �ith MRSA than patients of other age groups (p=0.02). Statisti- cal y significant differences in susceptibility rates bet�een MSSA and MRSA isolates �ere found for all antibiotic tested (p=0.0053 to p<0.000). MRSA isolates �ere more frequently multidrug resistant (MDR) than MSSA isolates (p=0.0009). SCCmec type IV or V phenotype �as detected in 30 (47.6%) of MRSA isolates. Conclusion Although lo� MRSA prevalence
�as noted, the presence of SCCmec type IV/V phenotypes in the community is of particular concern. Effective control of dissemination of MRSA throughout the community �ill likely require effective control and monitoring of nosocomial Key words: S. aureus, MRSA, MSSA, SCCmec, Resistance,
Introduction
defined CA-MRSA strains carry SCCmec type IV or V (14), �hereas the majority of Methicillin-resistant S. aureus (MRSA) has HA-MRSA strains carry SCCmec type I, II traditional y been considered a hospital- �ith established risk factors (recent hospi- from the noses and hands of food handlers talization or surgery, dialysis, residence in a prompted a retrospective revie� of Labora- long-term care facility, and presence of a per- tory outpatient records identifying patients manent ind�elling catheter or percutaneous from �hom S. aureus �as isolated from any medical device) at the time of culture) (1, 2). site in the period 2003-2005. The objective of this study �as to report the frequency of highly virulent organism in the community S. aureus isolation in outpatients from the of patients �ithout established risk factors govina, according to methicillin resistance, origin of isolates, age and gender of patients, methicillin resistant S. aureus (CA-MRSA) and to determine the antibiotic susceptibil- into hospitals has been reported, causing ity patterns. For comparison, S. aureus iso- lates obtained from food handlers and food products (routinely analysed in the Labora- talized patients, or patients upon admission tory during 2003-2004) �ere also included to hospital, �hich has probably resulted in an overestimation of the true prevalence of monly been based on the timing of isolation of MRSA in relation to the time of admission The Laboratory for Sanitary and Clinical to hospital, so that MRSA isolates �ere clas- Microbiology of the Cantonal Public Health sified as community-acquired if they �ere Institution in Zenica covers a population isolated �ithin the first 48-72 h of hospital- ization, or if they �ere isolated in a commu- (112,471 males and 218,758 females). In the 2003-2005 period, 13,937 consecutive sam- ples of nasal, throat, eye, ear and genitouri- vary �idely among studies, in part because nary tract s�abs, s�abs of �ound infections of the use of different definitions used to and soft and skin tissue infections (SSTIs) and sputum obtained from outpatients sub- MRSA, but also because of the different set- mitted to the Laboratory �ith clinical indi- tings in �hich studies have been performed. cation, �ere analyzed for the presence of S. Only a limited number of studies has been performed in outpatient settings and among Sterile cotton s�abs �ere used. S�abs �ere streaked onto sheep blood agar (5% columbia agar base) for detection of gram- positive bacteria, and incubated overnight niques �ith good resolving po�er provides a at 37°C. Morphological y distinct colonies reliable means of analysing isolates of MRSA �ere tested for the production of bound to determine their genetic relatedness (13, coagulase (Staphylase Test, Oxoid, Basing- 14). Recent studies have indicated that �ell- stoke, UK) and identified as S. aureus.
Selma .Uzunović-Kamberović .et .al .: .MRSA .in .the .community ler-Hinton agar (Oxoid, Besingstoke, UK) �as used to test against nine antimicrobials A total of 1583 (11.3%) nonduplicate S. au- (Oxoid, UK). Clinical and Laboratory Stan- reus isolates from 13 937 consecutive outpa- dards Institute (CLSI) criteria �ere used tients presented to the Laboratory because of different clinical symptoms �ere collected for the interpretation of antibiotic sensitiv- during 2003-2005. MRSA �as detected in 63 ity testing results (15). Oxacillin-resistant (4.1%) of S. aureus isolates and in 0.6% of strains �ere further tested by the E-test submitted samples. S. aureus �as identified (AB Biodisc, Solna, S�eden). Isolates �ere in 322 out of 4439 (7.3%) nasal s�abs of food considered resistant to oxacillin if the MIC handlers, five of �hich �ere MRSA (1.6%). exceeded 4 mg/L. The isolates characterized MRSA �as isolated in 0.1% of submitted as intermediate by both disk diffusion and food handler samples. Thirty five S. au- E-test �ere considered susceptible. Staphy- reus strains �ere isolated from 6517 (0.5%) lococcus aureus ATCC 25923 control strains food samples, and t�o of them (5.7%) �ere �ere used. Isolates resistant to oxacillin and MRSA. All S. aureus isolated from ice cream susceptible to gentamicin, clindamycin, and samples obtained from local patisseries and trimethoprim-sulfamethoxasole �ere des- ignated as having a SCCmec type IV or V Table 1 sho�s the distribution of methi- cillin susceptible S. aureus (MSSA) and MRSA isolates according to the origin of and age of the patient (0-6, 7-14, 20-64, >64 years), date of isolation, specimen number, MRSA isolates �ere more frequently iso- source of isolates and susceptibility results lated from genitourinary tract and �ounds of Staphylococcus aureus isolates �ere re- corded, as �ell as the number of specimens The patients in age groups ≥65 and 0-6 years of age �ere more frequently infect- For comparison, S. aureus strains isolated ed �ith MRSA than patients of other age from 4439 successive nasal s�abs of food- groups (p=0.02) (Table 2). Female patients handlers and 6517 samples of food collected �ere significantly more often infected �ith the Laboratory during 2003-2004 �ere also not sho�n). The median age of patients in- included in this study. Microbiological anal- fected �ith MRSA and MSSA �as 30.09 and ysis of food products �as performed accord- ing to the standards and legal regulations of Statistical y significant differences in sus- the Republic/Federation of Bosnia and Her- ceptibility rates bet�een MSSA and MRSA zegovina. Routine antimicrobial susceptibil- clinical isolates �ere found for all antibiotic ity testing of S. aureus isolates from these tested (p=0.0053 to p<0.0001) (Table 3). No samples �as terminated at the end of 2004, resistance to vancomycin or ciprofloxacin and for that reason the data for 2005 �ere �as detected in MRSA isolates. MRSA iso- lates �ere more frequently multidrug resis- The significance of differences in resis- tant (MDR) than MSSA isolates (p=0.0009). tance rates �as determined by means of According to origin, MDR �as more often the χ2 test and Fisher exact test for indepen- detected in �ound infection isolates, 28.6%, dence. A statistical y significant difference than in isolates from GU tract and nose, �as defined as a p value of <0.05 and 95% 12.5% and 0.6%, respectively, but �ith no statistical y significant difference (data not Table .1 .Distribution .of .MRSA .and .MSSA .clinical .isolates .of .different .origin .in .the .2003-2005 .period .
Table .2 .Distribution .of .MRSA .and .MSSA .clinical .isolates .according .to .age .groups Table .3 .Antimicrobial .resistance .patterns .of .MSSA .and .MRSA .isolates .in .the .2003-2005 .of .different .origin Percentage .of .resistance .to .antimicrobial .agents* MSSA, .methicillin-sensitive .Staphylococcus aureus; .MRSA, .methicillin-resistant .Staphylococcus aureus; .S, .susceptible; .
R, .resistance .to .one .or .more .antimicrobials; .MDR .(multidrug .resistance), .resistance .to .three .or .more .antimicrobials .
*Antimicrobial .agents .tested: .vancomycin .(VAN), .gentamicin .(GEN), .kanamycin .(KAN), .erythromycin .(ERY), .tetracycline .
(TET), .ciprofloxacin .(CIP), .clindamycin .(CLI), .trimethoprim-sulfamethoxasole .(SXT), .chloramphenicol .(CHL) famethoxasole) �as detected in 30 (47.6%) �ere significantly more often isolated from SCCmec type IV or V phenotype (isolates GU tract, �ounds and nose than from eyes resistant to oxacillin and susceptible to genta- (p=0.0005), but they �ere not isolated from micin, clindamycin, and trimethoprim-sul- Selma .Uzunović-Kamberović .et .al .: .MRSA .in .the .community Discussion
The finding of 30 MRSA isolates sho�ing strated that the prevalence of resistance to good sensitivity to antibiotics other than ciprofloxacin and erythromycin �as as high beta-lactams and the lo� prevalence of as 80% and 90%, respectively (22, 23). Fluo- roquinolone resistance emerged very rapidly gests the presence of true CA-MRSA in our in HA-MRSA in the years after �idespread population (2-4, 16) Multidrug resistance utilization of these agents (23-25). No resis- characterizes nosocomial y acquired MRSA tance to fluoroquinolones �as noted in this strains isolated from patients �ith identified study in MRSA isolates of any origin inves- tigated, but interestingly, it �as detected in Nasal carriage of S. aureus is an impor- tant risk factor for infections by this organ- ism in both community and hospital settings (16). Health-care exposure is significantly the SCCmec type IV / V phenotype, �hich is associated �ith MRSA carriage (10, 18). In typical for CA-MRSA isolates (7). All MRSA our study MRSA �as detected in 0.6% of isolated from food handlers and food prod- clinical samples submitted to our Laborato- ucts (ice cream) �ere SCCmec type IV or ry, �hich is in agreement �ith colonization V phenotype. SCCmec type IV/V type has increased mobility and therefore greater out healthcare contacts in the USA (0.2%) potential for horizontal spread to diverse S. aureus genetic backgrounds, compared �ith other SCCmec types (13, 14). We did not infections have been increasing among adults and children (4, 20). The results of the pres- type IV or V phenotype, but according to ent study have also sho�n that MRSA more the high correlation bet�een the genotype often infected the oldest (≥65) and youngest and phenotype �e could assume that at least (0-6) age groups of patients than other age some of these MRSA strains are generated in groups. Therefore, microbiologic culture and antimicrobial susceptibility testing �ould be This is a retrospective study �ith a relatively small sample size and accordingly, a small S. aureus and MRSA in food handlers and number of MRSA �ere analysed. Addition- their appearance in food products �as lo� al y, molecular analysis �as not perfomed and in agreement �ith the prevalence of S. and a risk factors involved in acquisition of aureus and MRSA infections in our region. MRSA infections �re not investigated. Also, data on the prevalence of HA-MRSA in this be a vehicle of outbreaks affecting lo�-risk region are missing. But, since �e found that persons �ithin the community and the food 25.4% (16/63) MRSA isolates �ere ful y �as contaminated by an asymptomatic car- susceptible to all antibiotic tested and 30 rier (21). There �ere no S. aureus foodborne (47.6%) MRSA isolates had SCCmec IV/V generated in the communitya might be pres- munity, but �e found that MRSA �ere more The origin of CA-MRSA strains is still the often isolated from the GU tract and �ound subject of debate. Only studies based on ap-
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