Epidemiology of methicillin-resistant Staphylococcus aureus in a university medical center day care facility

Prevalence and molecular characterizations of Staphylococcus aureus nasal colonization among patients in pediatric intensive care units in Taiwan

Background

Nasal colonization of Staphylococcus aureus is a risk factor for the pathogen transmission and the development of infections. Limited information is available on the prevalence and molecular characteristics of S. aureus colonization in pediatric intensive care unit (ICU) patients.

Methods

A cross-sectional, island-wide study was conducted in 2011. Nasal swabs were collected from pediatric ICU patients at six tertiary hospitals in Taiwan.

Results

Of 114 patients enrolled in total, nasal colonization of S. arueus was detected in 30 (26.3%) of them, among whom 20 (17.5%) with methicillin-resistant S. arueus (MRSA). The ST59/SCCmec IV and V clones were most common and accounted for 45% of MRSA isolates, followed by ST239/SCCmec III (25%) and ST45/SCCmec IV (20%) clones. Three ST59 MRSA isolates carried the Panton-Valentine Leukocidin genes.

Conclusions

The results indicated a high prevalence of S. arueus and MRSA nasal colonization among pediatric ICU patients in Taiwan. Identification of epidemic clones warrants the implement of infection control measures to reduce colonization and prevent the dissemination of MRSA in hospitals.

Prevalence and Molecular Characterization of Staphylococcus aureus and Methicillin-resistant S. aureus on Children's Playgrounds

BACKGROUND

Staphylococcus aureus is a major public health concern due to the emergence of virulent and drug-resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA). Although numerous studies have been conducted to assess the environmental contamination of S. aureus in health care and household settings, little is known about the prevalence and epidemiology of S. aureus, including MRSA, on environmental surfaces of children's playgrounds. This study investigated the prevalence and molecular epidemiology of S. aureus and MRSA at playgrounds in northeast Ohio.

METHODS

A total of 280 environmental samples were collected from 10 playgrounds in northeast Ohio in July 2016. Sampling sites were selected based on playground size and availability of equipment located in both small and large cities and their suburbs. Samples were analyzed using established microbiology methods, and resulting S. aureus isolates were typed by spa typing. Polymerase chain reaction was used to detect the presence of the Panton-Valentine leukocidin and mec A genes. Antibiotic susceptibility was tested via the Vitek-2 System.

RESULTS

The overall prevalence of S. aureus and MRSA was 31.8% (89/280) and 3.9% (11/280), respectively. A total of 43 spa types were detected from 257 S. aureus isolates. Overall, t189 was the most common spa type, accounting for 15.6% (40/257) of the isolates. Sixteen isolates (6.2%) were t002 (ST5/USA100), a common hospital-associated strain, and 11 isolates (4.3%) were t008 (ST8/USA300), a common community-associated strain. Five livestock-associated strain (t571/ST398) were also identified. Twenty-nine (11.3%) isolates were resistant to oxacillin, and 66 (25.7%) were multi-drug resistant S. aureus.

CONCLUSIONS

The results of this study indicate that environmental surfaces of playgrounds in northeastern Ohio were contaminated with S. aureus and MRSA. These data reinforce the need for implementing effective prevention strategies to mitigate the risk imposed to children by environmental contamination of MRSA.

Molecular characteristics of Staphylococcus aureus isolated from employees, children, and environmental surfaces in Iowa child daycare facilities

BACKGROUND

Infectious agents have the potential to thrive in child daycare facilities. Asymptomatic Staphylococcus aureus carriage is a risk factor for developing infection and contributes to transmission.

METHODS

We collected swabs from 110 employees, 111 unexposed adults, 81 children, and 214 environmental surfaces at 11 Iowa daycare facilities. S aureus isolates were characterized using antibiotic resistance profiles and Staphylococcal protein A typing. Staphylococcal protein A types were grouped into cluster complexes using the Based Upon Repeat Pattern algorithm.

RESULTS

All isolates (from 38 employees, 37 unexposed adults, 16 children, and 19 surfaces) were characterized. Daycare employees were more likely to carry erythromycin-resistant S aureus than unexposed adults (odds ratio, 3.7; 95% confidence interval, 1.1-12.7; P = .033). Isolates were genetically heterogeneous, although isolates from employees appeared more clonal than those from unexposed adults. Strains associated with ST8 were identified in 5 daycare facilities and 3 unexposed adults.

CONCLUSIONS

S aureus isolates collected from employees, children, and surfaces of daycare facilities are genetically heterogeneous, but contain strains associated with community-associated methicillin-resistant S aureus. This suggests that daycare facilities can serve as reservoirs for community-associated methicillin-resistant S aureus and facilitate genetic exchange. Employees may be at increased risk of carrying antibiotic-resistant strains, indicating more research is necessary into this occupational group.

Update on Epidemiology and Treatment of MRSA Infections in Children

In 2000-10 the epidemiology of pediatric MRSA infections in the United States was transformed with an epidemic of CA-MRSA infections. We review the epidemiology of MRSA in the community and in the health care setting, including intensive care units, among infants and CF patients, and in households as well as the impact that the CA-MRSA epidemic has had on hospitalization with MRSA infections. Risk factors for carriage, transmission, and initial and recurrent infection with MRSA are discussed. New studies on the treatment of pediatric MRSA infections and on the efficacy of MRSA decolonization are reviewed.

Risk ofStaphylococcus aureuscarriage in childcare employees

Asymptomatic carriage ofStaphylococcus aureusis an important risk factor for developing infection, as well as a key contributor to transmission. Despite the fact that childcare workers are at known risk for infections, little research has focused on bacterial carriage in this occupational group. We conducted a cross-sectional study comparing the prevalence ofS. aureusin 110 childcare employees with the prevalence in 111 unexposed participants. Questionnaire data was collected for employees, unexposed adults, and children. Multivariate analysis allowed for adjustment for confounders. Data on work-related exposures are presented as well. The prevalence ofS. aureusin employees, unexposed adults, children, and on surfaces was 35·2%, 33·6%, 19·8%, and 9·8%, respectively. Washing children's hands upon their arrival at childcare facilities may decrease the risk ofS. aureuscarriage in employees (odds ratio 0·17, 95% confidence interval 0·095–0·32,P < 0·0001).

Household transmission of meticillin-resistant Staphylococcus aureus and other staphylococci

Although the role of pets in household transmission of meticillin-resistant Staphylococcus aureus (MRSA) has been examined previously, only minor attention has been given to the role of the abiotic household environment independent of, or in combination with, colonisation of pets and human beings to maintain transmission cycles of MRSA within the household. This report reviews published work about household transmission of S aureus and other staphylococci and describes contamination of household environmental surfaces and colonisation of pets and people. Household microbial communities might have a role in transfer of antimicrobial resistance genes and could be reservoirs for recolonisation of people, although additional research is needed regarding strategies for decontamination of household environments. Household-based interventions should be developed to control recurrent S aureus infections in the community, and coordination between medical and veterinary providers could be beneficial.

Staphylococcus aureus colonization among household contacts of patients with skin infections: risk factors, strain discordance, and complex ecology

BACKGROUND

The USA300 methicillin resistant Staphylococcus aureus (MRSA) genetic background has rapidly emerged as the predominant cause of community-associated S. aureus infections in the U.S. However, epidemiologic characteristics of S. aureus household transmission are poorly understood.

METHODS

We performed a cross-sectional study of adults and children with S. aureus skin infections and their household contacts in Los Angeles and Chicago. Subjects were surveyed for S. aureus colonization of the nares, oropharynx, and inguinal region and risk factors for S. aureus disease. All isolates underwent genetic typing.

RESULTS

We enrolled 1162 persons (350 index patients and 812 household members). The most common infection isolate characteristic was ST8/SCCmec IV, PVL+ MRSA (USA300) (53%). S. aureus colonized 40% (137/350) of index patients and 50% (405/812) of household contacts. A nares-only survey would have missed 48% of S. aureus and 51% of MRSA colonized persons. Sixty-five percent of households had >1 S. aureus genetic background identified and 26% of MRSA isolates in household contacts were discordant with the index patients' infecting MRSA strain type. Factors independently associated (P < .05) with the index strain type colonizing household contacts were recent skin infection, recent cephalexin use, and USA300 genetic background.

CONCLUSIONS

In our study population, USA300 MRSA appeared more transmissible among household members compared with other S. aureus genetic backgrounds. Strain distribution was complex; >1 S. aureus genetic background was present in many households. S. aureus decolonization strategies may need to address extra-nasal colonization and the consequences of eradicating S. aureus genetic backgrounds infrequently associated with infection.

Predicting antibiotic resistance to community-acquired pneumonia antibiotics in culture-positive patients with healthcare-associated pneumonia

OBJECTIVE

To develop and validate a model to predict resistance to community-acquired pneumonia antibiotics (CAP-resistance) among patients with healthcare-associated pneumonia (HCAP), and to compare the model's predictive performance to a model including only guideline-defined criteria for HCAP.

DESIGN

Retrospective cohort study.

SETTING

Six Veterans Affairs Medical Centers in the northwestern United States.

PATIENTS

Culture-positive inpatients with HCAP.

MEASUREMENTS

Patients were identified based upon guideline-defined criteria for HCAP. Relevant cultures obtained within 48 hours of admission were assessed to determine bacteriology and antibiotic susceptibility. Medical records for the year preceding admission were assessed to develop predictive models of CAP-resistance with logistic regression. The predictive performance of cohort-developed and guideline-defined models was compared.

RESULTS

CAP-resistant organisms were identified in 118 of 375 culture-positive patients. Of guideline-defined criteria, CAP-resistance was associated (odds ratio (OR) [95% confidence interval (CI)]) with: admission from nursing home (2.6 [1.6-4.4]); recent antibiotic exposure (1.7 [1.0-2.8]); and prior hospitalization (1.6 [1.0-2.6]). In the cohort-developed model, CAP-resistance was associated with: admission from nursing home or recent nursing home discharge (2.3 [1.4-3.8]); positive methicillin-resistant Staphylococcus aureus (MRSA) history within 90 days of admission (6.4 [2.6-17.8]) or 91-365 days (2.3 [0.9-5.9]); cephalosporin exposure (1.8 [1.1-2.9]); recent infusion therapy (1.9 [1.0-3.5]); diabetes (1.7 [1.0-2.8]); and intensive care unit (ICU) admission (1.6 [1.0-2.6]). Area under the receiver operating characteristic curve (aROC [95% CI]) for the cohort-developed model (0.71 [0.65-0.77]) was significantly higher than for the guideline-defined model (0.63 [0.57-0.69]) (P = 0.01).

CONCLUSIONS

Select guideline-defined criteria predicted CAP-resistance. A cohort-developed model based primarily on prior MRSA history, nursing home residence, and specific antibiotic exposures provided improved prediction of CAP-resistant organisms in HCAP.

Are gymnasium equipment surfaces a source of staphylococcal infections in the community?

To determine the staphylococcal colonization of gymnasium surfaces, we obtained cultures of 5 gym surfaces, before and after routine cleaning in 3 local gyms, 3 separate times. Of 240 cultures, none was positive for methicillin-resistant Staphylococcus aureus (MRSA) or methicillin-sensitive S aureus (MSSA). Gym surfaces do not appear to be reservoirs for staphylococci; therefore, surface-to-skin contact in gymnasiums does not likely play a significant role in community transmission of MRSA or MSSA.

Prevalence and risk factor analysis for methicillin-resistant Staphylococcus aureus nasal colonization in children attending child care centers

Children attending child care centers (CCCs) are at increased risk for infections, including those caused by methicillin-resistant Staphylococcus aureus (MRSA). Nasal colonization often precedes infection, and MRSA colonization has been associated with increased infection risk. Community-associated MRSA (CA-MRSA) has caused increased MRSA infections in the general population, including children. Little is known about the frequency of MRSA nasal colonization in young children, particularly in those attending CCCs where disease transmission is common. We sampled the nares of 1,163 children in 200 classrooms from 24 CCCs in North Carolina and Virginia to assess S. aureus colonization. MRSA strains were molecularly analyzed for staphylococcal cassette chromosome mec (SCCmec) type, Panton-Valentine leukocidin status, and multilocus sequence type. A case-control study was performed to identify risk factors for MRSA colonization. We found that 18.1% children were colonized with S. aureus and 1.3% with MRSA. Molecular analysis of the MRSA strains identified 47% as CA-MRSA and 53% as health care-associated MRSA (HA-MRSA). Although two centers had multiple children colonized with MRSA, genotyping indicated that no transmission had occurred within classrooms. The case-control study did not detect statistically significant risk factors for MRSA colonization. However, MRSA-colonized children were more likely to be nonwhite and to have increased exposure to antibiotics and skin infections in the home. Both CA-MRSA and HA-MRSA strains were found colonizing the nares of children attending CCCs. The low frequency of colonization observed highlights the need for a large multicenter study to determine risk factors for MRSA colonization and subsequent infection in this highly susceptible population.

Epidemiology of methicillin-susceptible Staphylococcus aureus in a university medical center day care facility

BACKGROUND

Few data are available on methicillin-susceptible Staphylococcus aureus (MSSA) colonization in day care. We performed a study in a child care center on a medical university campus to study the epidemiology of MSSA in this population.

METHODS

A cross-sectional study was done on 104 day care attendees and 32 adult employees of the child care center. Swab samples were taken from the nose, oropharynx, axilla, groin, and perirectal area of children, from the nose and oropharynx of employees, and from the environment. Parents and employees completed questionnaires. Swabs were placed in broth, then plated on agar and identified as MSSA by routine methods. Molecular typing was performed.

RESULTS

The prevalence of MSSA was 21.15% in children and 28.13% in employees. MSSA was found in 8.72% of environmental samples. Univariate analysis identified 3 risk factors and 5 protective factors for MSSA colonization. In multivariable analysis, only 2 variables remained significantly related to MSSA colonization, with older age remaining as a risk factor and receipt of beta-lactams approaching significance as being protective. Many of the isolates were indistinguishable by molecular typing.

CONCLUSIONS

The prevalence of MSSA colonization in children and care providers in a university medical center child care center is similar to that of the general population. Children colonized with MSSA tended to be older and to have received fewer courses of antibiotics than children who did not have MSSA. The relatedness of many of the isolates indicates that transmission of MSSA occurred at this child care center.

The environment as a factor in methicillin-resistant Staphylococcus aureus transmission

In recent years, methicillin-resistant Staphylococcus aureus (MRSA) has become a leading cause of infectious disease morbidity and mortality in the United States. The epidemiology of the organism has changed, with novel strains emerging in the community among individuals lacking any healthcare contact. Although direct human-to-human transmission via skin contact is one way for this organism to spread, transmission via environmental contamination of fomites or through air are other potential ways that the organism can be acquired. As such, an improved understanding of MRSA transmission is needed to implement maximally effective control and prevention interventions. We review the research documenting the role of the environment in MRSA spread.