Community-associated methicillin-resistant Staphylococcus aureus colonization burden in HIV-infected patients

Socioeconomic status and the risk for colonisation or infection with priority bacterial pathogens: a global evidence map

Low socioeconomic status likely exacerbates risks for bacterial infections; however, global evidence for this relationship has not been synthesised. We systematically reviewed the existing literature for studies detailing the socioeconomic status of participants and their risk for colonisation or community-acquired infection with priority bacterial pathogens that are increasingly becoming antibiotic resistant. 50 studies from 14 countries reported outcomes by the participants' educational attainment, access to health care, income level, residential crowding status, socioeconomic status deprivation score, community setting, or access to clean water, sanitation, and hygiene. Low educational attainment, lower than average income levels, inadequate access to health care, presence of residential crowding, and high socioeconomic status deprivation scores were generally associated with elevated risks of colonisation or infection. Limited research has been conducted on these outcomes in low-income and middle-income countries, and findings regarding the effects of community settings (eg, urban vs rural) on these outcomes have been conflicting. Only a proportion of studies focused on pathogen colonisation and infection yielded data stratified by the socioeconomic status of participants. Stratified data should be included in future research to enhance understanding of the complex relationship between socioeconomic status and health, particularly in low-income and middle-income countries.

Therapy of Aspiration: Out-of-Hospital and In-Hospital-Acquired

Therapeutic considerations for aspiration pneumonia prioritize the risk of multidrug-resistant organisms. This involves integrating microbiological insights with each patient's unique risk profile, including the location at the time of aspiration, and whether it occurred in or out of the hospital. Our understanding of the microbiology of aspiration pneumonia has also evolved, leading to a reassessment of anaerobic bacteria as the primary pathogens. Emerging research shows a predominance of aerobic pathogens, in both community and hospital-acquired cases. This shift challenges the routine use of broad-spectrum antibiotics targeting anaerobes, which can contribute to antibiotic resistance and complications such as Clostridium difficile infections-concerns that are especially relevant given the growing issue of antimicrobial resistance. Adopting a comprehensive, patient-specific approach that incorporates these insights can optimize antibiotic selection, improve treatment outcomes, and reduce the risk of resistance and adverse effects.

Infectious Diseases Among People Experiencing Homelessness: A Systematic Review of the Literature in the United States and Canada, 2003-2022

Homelessness increases the risk of acquiring an infectious disease. We conducted a systematic review of the literature to identify quantitative data related to infectious diseases and homelessness. We searched Google Scholar, PubMed, and SCOPUS for quantitative literature published from January 2003 through December 2022 in English from the United States and Canada. We excluded literature on vaccine-preventable diseases and HIV because these diseases were recently reviewed. Of the 250 articles that met inclusion criteria, more than half were on hepatitis C virus or Mycobacterium tuberculosis. Other articles were on COVID-19, respiratory syncytial virus, Staphylococcus aureus, group A Streptococcus, mpox (formerly monkeypox), 5 sexually transmitted infections, and gastrointestinal or vectorborne pathogens. Most studies showed higher prevalence, incidence, or measures of risk for infectious diseases among people experiencing homelessness as compared with people who are housed or the general population. Although having increased published data that quantify the infectious disease risks of homelessness is encouraging, many pathogens that are known to affect people globally who are not housed have not been evaluated in the United States or Canada. Future studies should focus on additional pathogens and factors leading to a disproportionately high incidence and prevalence of infectious diseases among people experiencing homelessness.

Linking S. aureus Immune Evasion Mechanisms to Staphylococcal Vaccine Failures

Vaccination arguably remains the only long-term strategy to limit the spread of S. aureus infections and its related antibiotic resistance. To date, however, all staphylococcal vaccines tested in clinical trials have failed. In this review, we propose that the failure of S. aureus vaccines is intricately linked to prior host exposure to S. aureus and the pathogen's capacity to evade adaptive immune defenses. We suggest that non-protective immune imprints created by previous exposure to S. aureus are preferentially recalled by SA vaccines, and IL-10 induced by S. aureus plays a unique role in shaping these non-protective anti-staphylococcal immune responses. We discuss how S. aureus modifies the host immune landscape, which thereby necessitates alternative approaches to develop successful staphylococcal vaccines.

Socioeconomic status and the risk for colonization or infection with priority bacterial pathogens: a global evidence map

Low socioeconomic status (SES) is thought to exacerbate risks for bacterial infections, but global evidence for this relationship has not been synthesized. We systematically reviewed the literature for studies describing participants' SES and their risk of colonization or community-acquired infection with priority bacterial pathogens. Fifty studies from 14 countries reported outcomes by participants' education, healthcare access, income, residential crowding, SES deprivation score, urbanicity, or sanitation access. Low educational attainment, lower than average income levels, lack of healthcare access, residential crowding, and high deprivation were generally associated with higher risks of colonization or infection. There is limited research on these outcomes in low- and middle-income countries (LMICs) and conflicting findings regarding the effects of urbanicity. Only a fraction of studies investigating pathogen colonization and infection reported data stratified by participants' SES. Future studies should report stratified data to improve understanding of the complex interplay between SES and health, especially in LMICs.

Aspiration Pneumonia

Aspiration pneumonia is a lower respiratory tract infection that results from inhalation of foreign material, often gastric and oropharyngeal contents. It is important to distinguish this from a similar entity, aspiration with chemical pneumonitis, as treatment approaches may differ. An evolving understanding of the human microbiome has shed light on the pathogenesis of aspiration pneumonia, suggesting that dysbiosis, repetitive injury, and inflammatory responses play a role in its development. Risk factors for aspiration events involve a complex interplay of anatomical and physiological dysfunctions in the nervous, gastrointestinal, and pulmonary systems. Current treatment strategies have shifted away from anaerobic organisms as leading pathogens. Prevention of aspiration pneumonia primarily involves addressing oropharyngeal dysphagia, a significant risk factor for aspiration pneumonia, particularly among elderly individuals and those with cognitive and neurodegenerative disorders.

Co-carriage of Staphylococcus aureus and Streptococcus pneumoniae among children younger than 2 years of age in a rural population in Pakistan

Objectives

Staphylococcus aureus and Streptococcus pneumoniae are common colonizers of the human nasopharynx. In this study, we describe S. aureus nasopharyngeal carriage and evaluate its association with S. pneumoniae carriage post-10-valent pneumococcal conjugate vaccine (PCV10) introduction in Pakistan.

Methods

A serial cross-sectional study was undertaken from 2014 to 2018, children <2 years were randomly selected, and nasopharyngeal swabs were collected using standard WHO guidelines. S. aureus and S. pneumoniae isolates were identified using standard methods and tested for antimicrobial susceptibility by the standard Kirby-Bauer disk-diffusion method as per Clinical & Laboratory Standards Institute (CLSI) recommendations. Regression analysis was used to determine predictors associated with S. aureus carriage.

Results

We enrolled 3140 children. S. aureus carriage prevalence was 5.6% (176/3140), and 50.1% (81/176) of the isolates were methicillin-resistant S. aureus (MRSA). S. aureus carriage was higher in the absence of pneumococcus compared to isolates in which pneumococcus was present (7.5% vs 5.0%). S. aureus carriage was negatively associated with pneumococcal carriage, being in 3rd and 4th year of enrollment, and vaccination with two and three PCV10 doses, in addition, fast breathing, ≥2 outpatients visits, and rainy season were positively associated. The following resistance rates were observed: 98.9% for penicillin, 74.4% for fusidic acid, and 23.3% for gentamicin, 10.2% for erythromycin, and 8.5% for cotrimoxazole. All isolates were susceptible to amikacin.

Conclusions

Overall S. aureus carriage prevalence was low, PCV10 vaccine was protective against the carriage. The proportion of MRSA carriage and antimicrobial resistance was high in this community warranting continuous monitoring for invasive infections.

Bacterial Genotype, Carrier Risk Factors, and an Antimicrobial Stewardship Approach Relevant To Methicillin-resistant Staphylococcus Aureus Prevalence in a Population of Macaques Housed in a Research Facility

Methicillin-resistant Staphylococcus aureus (MRSA) remains a significant problem for human and animal health and can negatively affect the health status of macaques and other nonhuman primates (NHP) in research colonies. However, few publications provide guidance on the prevalence, genotype, or risk factors for macaques with MRSA and even fewer on how to effectively respond to MRSA once identified in a population. After having a clinical case of MRSA in a rhesus macaque, we sought to determine the MRSA carrier prevalence, risk factors, and genotypes of MRSA in a population of research NHPs. Over a 6-wk period in 2015, we collected nasal swabs from 298 NHPs. MRSA was isolated from 28% (n = 83). We then reviewed each macaque's medical record for a variety of variables including animal housing room, sex, age, number of antibiotic courses, number of surgical interventions, and SIV status. Analysis of these data suggests that MRSA carriage is associated with the room location, age of the animal, SIV status, and the number of antibiotic courses. We used multilocus sequence typing and spa typing on a subset of MRSA and MSSA isolates to determine whether the MRSA present in NHPs was comparable with common human strains. Two MRSA sequence types were predominant: ST188 and a novel MRSA genotype, neither of which is a common human isolate in the United States. We subsequently implemented antimicrobial stewardship practices (significantly reducing antimicrobial use) and then resampled the colony in 2018 and found that MRSA carriage had fallen to 9% (26/285). These data suggest that, as in humans, macaques may have a high carrier status of MRSA despite low clinically apparent disease. Implementing strategic antimicrobial stewardship practices resulted in a marked reduction in MRSA carriage in the NHP colony, highlighting the importance of limiting antimicrobial use when possible.

Prevalence and genetic lineages of Staphylococcus aureus nasal colonization and urinary tract infection among people living with HIV/AIDS in Nigeria: A systematic review

To provide an empirical insight on Staphylococcus aureus (S. aureus) nasal colonization and urinary tract infection (UTI) among people living with HIV/AIDS (PLWHA) in Nigeria, a quantitative synthesis and systematic review were executed. A comprehensive bibliometric search was conducted for published articles using the keywords 'nasal S. aureus carriage', 'Urinary S. aureus', 'nasal MRSA', 'staphylococci-HIV coinfection', 'urinary MRSA' and 'all states of Nigeria'. Eligible studies and the number of subjects (n) were analysed according to the PRISMA criteria. Out of the 79 examined studies, only 6 (n=1181) and 6 (n= 1350) on nasal and urine samples, respectively, were eligible. The pooled prevalence of nasal carriage and UTI of S. aureus were 29.6% and 6.8%, respectively. However, the pooled nasal MRSA carriage was 13.4%. The pooled prevalence of luk-F/S-PV-carrying S. aureus among nasal samples was 13.0%. Molecular typing from 3 studies showed MRSA-ST8-t064 and MSSA-ST15-t084 as the predominant genetic lineages. The S. aureus isolates from both sample types had the highest (>50%) resistance to penicillin, sulfamethoxazole-trimethoprim, erythromycin, and tetracycline. Multi-drug resistance was not significantly higher among S. aureus isolates from urine than nasal samples (60% versus 40.0% of eligible studies) (p= 0.5271). A moderate and high pooled prevalence of genetically diverse MRSA and luk-F/S-PV-carrying S. aureus were obtained from PLWHA, respectively. These findings emphasize the importance of routine screening for MRSA among PLWHA in Nigeria and other HIV endemic countries.

High prevalence of Panton-Valentine leukocidin positive, multidrug resistant, Methicillin-resistant Staphylococcus aureus strains circulating among clinical setups in Adamawa and Far North regions of Cameroon

Staphylococcus aureus (S. aureus) is one of the earliest pathogens involved in human infections, responsible for a large variety of pathologies. Methicillin was the first antibiotic used to treat infections due to S. aureus but infections due to Methicillin resistant Staphylococcus aureus (MRSA) originated from hospital settings. Later, severe infections due to MRSA without any contact with the hospital environment or health care workers arose. Prevalence of MRSA has shown an alarming increase worldover including Cameroon. This Cross-sectional study was designed to evaluate the occurrence of MRSA infections in five different, most frequented Hospitals in northern Cameroon. Socio demographic data was recorded through questionnaire and different clinical specimens were collected for bacterial isolation. Identification of S. aureus was confirmed via 16s rRNA amplification using S. aureus specific primers. Molecular characterisation was performed through mecA gene, Luk PV gene screening and SCCmec typing. A total of 380 S. aureus clinical isolates were obtained of which 202 (53.2%) were nonduplicate multidrug resistant isolates containing, 45.5% MRSA. Higher number of MRSA was isolated from pus (30.4%) followed by blood culture (18.5%), and urine (17.4%). Patients aged 15 to 30 years presented high prevalence of MRSA (30.4%). Majority isolates (97.8%) carried the mecA gene, PVL toxin screening indicated 53.3% isolates carried the lukPV gene. Based on PVL detection and clinical history, CA-MRSA represented 53.3% of isolates. SCCmec typing showed that the Type IV was most prevalent (29.3%), followed by type I (23.9%). Amongst MRSA isolates high resistance to penicillin (91.1%), cotrimoxazole (86.7%), tetracycline (72.2%), and ofloxacin (70.0%) was detected. Meanwhile, rifampicin, fusidic acid, lincomycin and minocycline presented high efficacy in bacterial control. This study revealed a high prevalence of MRSA among infections due to S. aureus in Northern Cameroon. All MRSA recorded were multidrug resistant and the prevalence of CA MRSA are subsequently increasing, among population.

Staphylococcus aureus-induced immunosuppression mediated by IL-10 and IL-27 facilitates nasal colonisation

Staphylococcus aureus persistently colonises the anterior nares of a significant proportion of the healthy population, however the local immune response elicited during S. aureus nasal colonisation remains ill-defined. Local activation of IL-17/IL-22 producing T cells are critical for controlling bacterial clearance from the nasal cavity. However, recurrent and long-term colonisation is commonplace indicating efficient clearance does not invariably occur. Here we identify a central role for the regulatory cytokine IL-10 in facilitating bacterial persistence during S. aureus nasal colonisation in a murine model. IL-10 is produced rapidly within the nasal cavity following S. aureus colonisation, primarily by myeloid cells. Colonised IL-10^-/- mice demonstrate enhanced IL-17+ and IL-22+ T cell responses and more rapidly clear bacteria from the nasal tissues as compared with wild-type mice. S. aureus also induces the regulatory cytokine IL-27 within the nasal tissue, which acts upstream of IL-10 promoting its production. IL-27 blockade reduces IL-10 production within the nasal cavity and improves bacterial clearance. TLR2 signalling was confirmed to be central to controlling the IL-10 response. Our findings conclude that during nasal colonisation S. aureus creates an immunosuppressive microenvironment through the local induction of IL-27 and IL-10, to dampen protective T cell responses and facilitate its persistence.

Nasal colonisation by the bacterium Staphylococcus aureus is a very common occurrence in the human population. However there is a lack of knowledge on the immune response that controls nasal colonisation. It is known that a local pro-inflammatory immune response is important for bacterial clearance, however sustained colonisation is commonplace suggesting efficient clearance may not be occurring. Here we demonstrate for the first time that S. aureus is manipulating the host immune response by promoting immunosuppression in the nasal cavity which enables bacterial survival. We found that the regulatory proteins IL-10 and IL-27 are central to this suppressive response and result in reduced protective T cell responses. We also demonstrate that S. aureus is inducing IL-27 production to enhance IL-10 production in order to prolong bacterial colonisation. Our findings show that the host-pathogen interaction during nasal colonisation is more complex than previously described and that S. aureus is capable of manipulating the regulatory immune response of the host for its’ own benefit.

Methicillin-resistant Staphylococcus aureus nasal colonization in people living with HIV and healthy people in Kathmandu, Nepal

AIM

This study aimed to compare methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization in people living with HIV (PLHIV) and healthy people from Kathmandu.

METHODS

MRSA isolated from 400 nasal swabs was screened using a cefoxitin disc and confirmed by the presence of the mecA gene.

RESULTS

MRSA nasal carriers among the PLHIV and control cohorts were 3.5% (7 out of 200) and 5.0% (10 out of 200), respectively. All the MRSA from PLHIV and most of MRSA from healthy controls were PVL positive. Longer duration of antiretroviral therapy significantly reduces the risk of MRSA nasal colonization in PLHIV.

CONCLUSION

There is no significant difference in MRSA nasal colonization in PLHIV and healthy controls in this study region.

Genomic Analysis of Community Transmission Networks for MRSA among Females Entering a Large Inner-City Jail

Background

It is unclear if there are differences in MRSA risk between sexes in high-risk populations.

Methods

Females incarcerated at the Cook County Jail were enrolled within 72 hours of intake. Surveillance cultures (nares, throat, groin) were collected to determine prevalence of MRSA colonization. A survey was administered to identify colonization predictors. Univariate and multivariate analyses were performed to identify predictors of colonization at intake. Genomic sequencing was performed on MRSA colonization and archived clinical isolates.

Results

250 women were enrolled (70% AA, 15% Hispanic) with 70% previously in jail. The prevalence of MRSA colonization at intake was 20%, with 42% of those colonized solely in the throat or groin. Univariate predictors of MRSA colonization at entrance were illicit drug use, unstable housing, engaging in anal sex, recent exchange of sex for drugs/money, and a higher number of recent sexual partners. With multivariate adjustment for race/ethnicity, use of needles for illicit drugs was a significant predictor of MRSA. Use of illicit drugs was also associated with inclusion in a genomic cluster.

Nares colonization was significantly associated with not being in a genomic cluster (18.8% vs 78.6%, p&lt;0.001), whereas exclusive extra-nasal colonization was associated (OR 15.89, p&lt;0.001).

Conclusion

We found that a high proportion (20%) of females entered jail colonized with MRSA, suggesting that previously reported sex disparities of a lower risk in women may not apply to high-risk populations. Our findings suggest high-risk activities or venues in the community for MRSA, with potential for directing sex-specific interventions.

Risk factors for methicillin-resistant Staphylococcus aureus colonization and infection in patients with human immunodeficiency virus infection: A systematic review and meta-analysis

OBJECTIVE

To investigate the potential factors affecting methicillin-resistant Staphylococcus aureus (MRSA) colonization and infection in patients with human immunodeficiency virus (HIV) infection.

METHODS

A systematic search of publications listed in electronic from inception up to August 2020 was conducted. A random-effects model was used to calculate odds ratio (OR) with 95% confidence interval (CI).

RESULTS

A total of 31 studies reporting 1410 MRSA events in 17 427 patients with HIV infection were included. Previous hospitalization (OR 1.80; 95% CI 1.37, 2.36), previous antibiotic therapy (OR 2.69; 95% CI 2.09, 3.45), CD4+ count (OR 1.79; 95% CI 1.41, 2.28), Centers for Disease Control and Prevention classification of stage C (OR 2.66; 95% CI 1.80, 3.93), skin lesions (OR 2.02; 95% CI 1.15, 3.55), intravenous device use (OR 2.61; 95% CI 1.59, 4.29) and an MRSA colonization history (OR 6.30; 95% CI 2.50, 15.90) were significantly associated with an increased risk of MRSA colonization and infection. Antiretroviral therapy (OR 0.71; 95% CI 0.50, 0.99) and current antibiotic use (OR 0.13; 95% CI 0.05, 0.32) were significantly associated with a reduced risk of MRSA colonization and infection.

CONCLUSION

MRSA colonization and infection in HIV-infected patients is associated with a number of risk factors.

An evaluation of risk factors for Staphylococcus aureus colonization in a pre-surgical population

Staphylococcus aureus (SA) colonization has significant implications in healthcare-associated infections. Here we describe a prospective study conducted in pre-surgical outpatients, done with the aim of identifying demographic and clinical risk factors for SA colonization. We found younger age to be a potential predictor of SA colonization.

Methicillin resistance Staphylococcus aureus nasal carriage and its associated factors among HIV patients attending art clinic at Dessie comprehensive specialized hospital, Dessie, North East Ethiopia

Globally the incidence of nosocomial infections and colonization due to methicillin resistant Staphylococcus aureus (MRSA) has become greater concern. The objective of the study was to determine the prevalence and associated factors of nasal carriage of MRSA with its antimicrobial susceptibility patter among HIV patients attending ART clinic. cross-sectional study was conducted from January 01 to May 30, 2020 at Dessie comprehensive specialized hospital, north east Ethiopia. A total of 206 HIV patients were recruited by applying systematic random sampling technique. Nasal specimen was collected from both anterior nares, and inoculated directly on mannitol salt agar, MacConkey, 5% blood agar. Screening of MRSA and methicillin susceptible Staphylococcus aureus (MSSA) strain was done by using cefoxitin antibiotic disc following modified Kirby-Bauer disc diffusion technique. Bivariable and multivariable logistic regression analyses were performed to assess the associated factors with S. aureus and MRSA. study participants were in the age range between 12 and 72 years and their mean (±SD) age was 41.52 (±11.2). The rate of S. aureus and MRSA colonization was 127/206 (61.7%) and 58/206 (28.2%), respectively. Having job close contact with human [AOR = 4.41; 95% CI = 1.5-13.02; p = 0.007], picking the nose [AOR = 4.38; 95% CI = 1.34-14.29; p = 0.014] and ART failure [AOR = 7.41; 95% CI = 2.08-26.41; p = 0.002] had statistically significant association with MRSA colonization. MRSA showed resistance for tetracycline (53.4%), erythromycin (84.5%), and trimethoprim-sulfamethoxazole (86.2%). Multi-Drug Resistance (MDR) was detected among 96.5% of MRSA and 20.3% of MSSA isolates. the rate of S. aureus and MRSA nasal colonization was high and it has associated with different factors. Understanding and managing MRSA among HIV patients is mandatory and stakeholders should find out the way how to decolonize the bacteria from nasal area.

Understanding Dermatologic Concerns Among Persons Experiencing Homelessness: A Scoping Review and Discussion for Improved Delivery of Care

There is a paucity of information surrounding dermatologic care for persons experiencing homelessness (PEH). This scoping review aims to map existing literature and provide a summary of the most common cutaneous manifestations among PEH, risk factors for dermatologic disease, describe any reported interventions, as well as identify research gaps for future studies. Search strategies developed for MEDLINE and hand searching yielded 486 articles. Out of the 486 articles screened, 93 articles met the inclusion criteria. The majority were cohort studies, cross-sectional studies, and case-control studies concentrated in North America and Europe. Excluding the pediatric population, the prevalence of dermatologic conditions ranged from 16.6% to 53.5%. Common skin conditions described in PEH were: acne, psoriasis, seborrheic dermatitis, atopic dermatitis, and lichen simplex chronicus. There were no studies comparing the extent or severity of these cutaneous diseases in PEH and the general population. PEH have a higher prevalence of skin infections and non-melanoma skin cancers. This scoping review has direct implications on public health interventions for PEH and highlights the need for evidence-based interventions to provide optimum and safe dermatologic healthcare for PEH. We propose several recommendations for improved care delivery, including addressing upstream factors and comorbidities impacting skin health, providing trauma informed care, reducing barriers to care, preventing and managing skin conditions, as well as including PEH in the planning and implementation of any proposed intervention.

Frequent Methicillin-Resistant Staphylococcus aureus Introductions Into an Inner-city Jail: Indications of Community Transmission Networks

BACKGROUND

Jails may facilitate spread of methicillin-resistant Staphylococcus aureus (MRSA) in urban areas. We examined MRSA colonization upon entrance to a large urban jail to determine if there are MRSA transmission networks preceding incarceration.

METHODS

Males incarcerated in Cook County Jail (Chicago) were enrolled, with enrichment for people living with human immunodeficiency virus (PLHIV), within 72 hours of intake. Surveillance cultures assessed prevalence of MRSA colonization. Whole-genome sequencing (WGS) identified preincarceration transmission networks.We examined methicillin-resistant Staphylococcus aureus (MRSA) isolates to determine if there are transmission networks that precede incarceration. A large proportion of individuals enter jail colonized with MRSA. Molecular epidemiology and colonization risk factors provide clues to community reservoirs for MRSA.

RESULTS

There were 718 individuals (800 incarcerations) enrolled; 58% were PLHIV. The prevalence of MRSA colonization at intake was 19%. In multivariate analysis, methamphetamine use, unstable housing, current/recent skin infection, and recent injection drug use were predictors of MRSA. Among PLHIV, recent injection drug use, current skin infection, and HIV care at outpatient clinic A that emphasizes comprehensive care to the lesbian, gay, bisexual, transgender community were predictors of MRSA. Fourteen (45%) of 31 detainees with care at clinic A had colonization. WGS revealed that this prevalence was not due to clonal spread in clinic but rather to an intermingling of distinct community transmission networks. In contrast, genomic analysis supported spread of USA500 strains within a network. Members of this USA500 network were more likely to be PLHIV (P < .01), men who have sex with men (P < .001), and methamphetamine users (P < .001).

CONCLUSIONS

A large proportion of individuals enter jail colonized with MRSA. Molecular epidemiology and colonization risk factors provide clues to identify colonized detainees entering jail and potential community reservoirs of MRSA.

Predominance of PVL-negative community-associated methicillin-resistant Staphylococcus aureus sequence type 8 in newly diagnosed HIV-infected adults, Tanzania

Difficult-to-treat infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are of concern in people living with HIV infection as they are more vulnerable to infection. We aimed to identify molecular characteristics of MRSA colonizing newly diagnosed HIV-infected adults in Tanzania. Individuals newly diagnosed with HIV infection were recruited in Dar es Salaam, Tanzania, from April 2017 to May 2018, as part of the randomized clinical trial CoTrimResist (ClinicalTrials.gov identifier: NCT03087890). Nasal/nasopharyngeal isolates of Staphylococcus aureus were susceptibility tested by disk diffusion method, and cefoxitin-resistant isolates were characterized by short-reads whole genome sequencing. Four percent (22/537) of patients carried MRSA in the nose/nasopharynx. MRSA isolates were frequently resistant towards gentamicin (95%), ciprofloxacin (91%), and erythromycin (82%) but less often towards trimethoprim-sulfamethoxazole (9%). Seventy-three percent had inducible clindamycin resistance. Erythromycin-resistant isolates harbored ermC (15/18) and LmrS (3/18) resistance genes. Ciprofloxacin resistance was mediated by mutations of the quinolone resistance-determining region (QRDR) sequence in the gyrA (S84L) and parC (S80Y) genes. All isolates belonged to the CC8 and ST8-SCCmecIV MRSA clone. Ninety-five percent of the MRSA isolates were spa-type t1476, and one exhibited spa-type t064. All isolates were negative for Panton-Valentine leucocidin (PVL) and arginine catabolic mobile element (ACME) type 1. All ST8-SCCmecIV-spa-t1476 MRSA clones from Tanzania were unrelated to the globally successful USA300 clone. Carriage of ST8 MRSA (non-USA300) was common among newly diagnosed HIV-infected adults in Tanzania. Frequent co-resistance to non-beta lactam antibiotics limits therapeutic options when infection occurs.

Skin and Soft Tissue Infection in People Living With Human Immunodeficiency Virus in a Large, Urban, Public Healthcare System in Houston, Texas, 2009-2014

BACKGROUND

Skin and soft tissue infections (SSTIs) disproportionately impact patients with human immunodeficiency virus (HIV). Recent declines in the incidence of SSTIs have been noted in the non-HIV population. We sought to study the epidemiology and microbiology of SSTIs in a population of 8597 patients followed for HIV primary care in a large, urban county system from January 2009 to December 2014.

METHODS

SSTIs were identified from the electronic medical record by use of International Classification of Diseases-9 billing codes. Charts were reviewed to confirm each patient's diagnosis of acute SSTI and abstract culture and susceptibility data. We calculated the yearly SSTI incidences using Poisson regression with clustering by patient.

RESULTS

There were 2202 SSTIs identified. Of 503 (22.8%) cultured SSTIs, 332 (66.0%) recovered Staphylococcus aureus as a pathogen, of which 287/332 (86.4%) featured S. aureus as the sole isolated organism. Among the S. aureus isolates that exhibited antibiotic susceptibilities, 231/331 (69.8%) were methicillin resistant, and the proportion did not change by year. The observed incidence of SSTI was 78.0 per 1000 person-years (95% confidence interval 72.9-83.4) and declined from 96.0 infections per 1000 person-years in 2009 to 56.5 infections per 1000 person-years in 2014 (P < .001). Other significant predictors of SSTI incidences in both univariate as well as multivariate analyses included a low CD4 count, high viral load, and not being a Spanish-speaking Hispanic.

CONCLUSIONS

SSTIs remain a significant problem in the outpatients living with HIV, although rates of SSTIs appear to have declined by approximately 40% between 2009 and 2014.

Genomic Epidemiology of MRSA During Incarceration at a Large Inner-City Jail

BACKGROUND

Congregate settings, such as jails, may be a location where colonized detainees transmit MRSA. We examined MRSA acquisition during incarceration and characterized the genomic epidemiology of MRSA entering the jail and isolated during incarceration.

METHODS

Males incarcerated at the Cook County Jail were enrolled within 72 hours of intake and MRSA surveillance cultures collected. Detainees in jail at Day30 were re-cultured to determine MRSA acquisition. A survey was administered to identify acquisition predictors. Genomic sequencing of surveillance and clinical isolates was integrated with epidemiologic and jail location data to track MRSA transmission pathways.

RESULTS

800 males were enrolled; 19% MRSA colonized at intake. Of 184 who reached Day30 visit, 12 acquired MRSA. Heroin use before entering (OR 3.67,p=0.05) and sharing personal items during incarceration (OR=4.92,p=.01) were predictors of acquisition. Sequenced clinical USA300 isolates (n=112) were more genetically similar than diverse intake USA300 strains (p<0.001), suggesting jail transmission. Four acquired colonization isolates were within 20 SNVs of other isolates; 4 were within 20SNVs of an intake isolate, 2 for an acquisition isolate, and 1 for a clinical isolate. Individuals with genetically similar isolates were more likely to have had overlapping stays in the same buildings.

CONCLUSION

There was a high MRSA burden entering jail. Genomic analysis of acquisition and clinical isolates suggests potential spread of incoming strains and networks of spread during incarceration, with spread often occurring among detainees housed in similar locations. Sharing personal items during incarceration is associated with MRSA acquisition and could be a focus for intervention.

Mathematical Model of the Role of Asymptomatic Infection in Outbreaks of Some Emerging Pathogens

Preparation for outbreaks of emerging infectious diseases is often predicated on beliefs that we will be able to understand the epidemiological nature of an outbreak early into its inception. However, since many rare emerging diseases exhibit different epidemiological behaviors from outbreak to outbreak, early and accurate estimation of the epidemiological situation may not be straightforward in all cases. Previous studies have proposed considering the role of active asymptomatic infections co-emerging and co-circulating as part of the process of emergence of a novel pathogen. Thus far, consideration of the role of asymptomatic infections in emerging disease dynamics have usually avoided considering some important sets of influences. In this paper, we present and analyze a mathematical model to explore the hypothetical scenario that some (re)emerging diseases may actually be able to maintain stable, endemic circulation successfully in an entirely asymptomatic state. We argue that an understanding of this potential mechanism for diversity in observed epidemiological dynamics may be of considerable importance in understanding and preparing for outbreaks of novel and/or emerging diseases.

An Outbreak of USA300 Methicillin-Resistant Staphylococcus aureus Among People With HIV in Japan

BACKGROUND

USA300 produces Panton-Valentin leucocidin (PVL) and is known as a predominant community-associated methicillin-resistant Staphylococcus aureus (MRSA) strain in the United States, but it was extremely rare in Japan. We report here an outbreak of USA300 in people with HIV (PWH) in Tokyo, Japan.

METHODS

We analyzed the cases of PVL-MRSA infection between 2010 and 2020 and screened for nasal colonization of PVL-MRSA in PWH who visited an HIV/AIDS referral hospital from December 2019 to March 2020. Whole-genome sequencing-based single nucleotide polymorphism (SNP) analysis was performed on these isolates.

RESULTS

During the study period, a total of 21 PVL-MRSA infections in 14 patients were identified after 2014. The carriage prevalence was 4.3% (12/277) and PVL-MRSA carriers were more likely to have sexually transmitted infections (STIs) within a year compared with patients who had neither a history of PVL-MRSA infection nor colonization (33.3% [4/12] vs 10.1% [26/258]; P = .03). SNP analysis showed that all 26 isolates were ST8-SCCmecIVa-USA300. Twenty-four isolates were closely related (≤100 SNP differences) and had the nonsynonymous SNPs associated with carbohydrate metabolism and antimicrobial tolerance.

CONCLUSIONS

An outbreak of USA300 has been occurring among PWH in Tokyo and a history of STI was a risk of colonization.

Challenges and New Therapeutic Approaches in the Management of Chronic Wounds

Chronic non-healing wounds are estimated to cost the US healthcare $28-$31 billion per year. Diabetic ulcers, arterial and venous ulcers, and pressure ulcers are some of the most common types of chronic wounds. The burden of chronic wounds continues to rise due to the current epidemic of obesity and diabetes and the increase in elderly adults in the population who are more vulnerable to chronic wounds than younger individuals. This patient population is also highly vulnerable to debilitating infections caused by opportunistic and multi-drug resistant pathogens. Reduced microcirculation, decreased availability of cytokines and growth factors that promote wound closure and healing, and infections by multi-drug resistant and biofilm forming microbes are some of the critical factors that contribute to the development of chronic non-healing wounds. This review discusses novel approaches to understand chronic wound pathology and methods to improve chronic wound care, particularly when chronic wounds are infected by multi-drug resistant, biofilm forming microbes.

Observational study of skin and soft-tissue Staphylococcus aureus infection in patients infected with HIV-1 and epidemics of Panton-Valentine leucocidin-positive community-acquired MRSA infection in Osaka, Japan

BACKGROUND

In patients infected with human immunodeficiency virus (HIV)-1 at our hospital, we observed increases in skin and soft-tissue infections (SSTIs) by community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). Therefore, we analyzed factors related to CA-MRSA infection and performed a molecular epidemiological investigation.

METHODS

HIV-1-infected patients were diagnosed with SSTIs related to S. aureus between 2007 and 2017, and MRSA was classified into community and hospital-acquired types according to published criteria. Information was collected retrospectively from clinical records, and multivariate analysis by logistic regression was performed concerning factors related to CA-MRSA infection. We evaluated the staphylococcal cassette chromosome mec (SCCmec) type, multilocus sequence type, and the presence of genes encoding Panton-Valentine leucocidin (PVL) in 27 MRSA samples isolated during and after 2015.

RESULTS

We found 218 episodes of SSTIs in 169 patients, and among initial episodes of SSTIs, the MRSA ratio was higher from 2015 to 2017 relative to that from 2007 to 2014 (88% vs. 44%; p < 0.0001). Multivariate analysis showed that in men having sex with men [MSM; odds ratio (OR): 13] and exhibiting onset during and after 2015 (OR: 5.4), CD4⁺ cell count ≥200 cells/μL (OR: 5.6) and the presence of lesions in the lower abdomen or buttocks (OR: 9.5) were independent factors related to CA-MRSA infection. Additionally, PVL+/ST8/SCCmec type IV MRSA was the predominant pathogen (22 cases; 81%).

CONCLUSIONS

These data describe an increased prevalence of SSTIs due to PVL-positive ST8-MRSA-IV, not previously considered epidemic in Japan, in MSM infected with HIV-1 in Osaka, Japan.

Staphylococcus aureus Nasal Colonization among Children with Sickle Cell Disease at the Children's Hospital, Accra: Prevalence, Risk Factors, and Antibiotic Resistance

The aim of this study was to investigate S. aureus carriage among children with sickle cell disease (SCD), including the prevalence, risk factors, and antibiotic resistance. The study was cross-sectional, and involved 120 children with SCD recruited at the Princess Marie Louise Children’s Hospital (PML) in Accra and 100 apparently healthy children from environs of the hospital. Nasal swab samples were collected from the study participants and cultured for bacteria. Confirmation of S. aureus and methicillin-resistant Staphylococcus aureus (MRSA) isolates were done using the tube coagulase test and mecA polymerase chain reaction, respectively. All the S. aureus isolates were tested against standard antimicrobial agents using the Kirby-Bauer method. A structured questionnaire was used to obtain the socio-demographic and clinical data of the study participants. Binary logistic regression was used to identify determinants of S. aureus and MRSA carriage among the study participants. The nasal carriage prevalence of S. aureus was 33.3% (n = 40) and 10% (n = 10) among the participants of the SCD and control groups, respectively. As regards MRSA nasal carriage prevalence, the respective values were 3.33% (n = 4) and 0.00% (n = 0). SCD was significantly associated with S. aureus colonization (p < 0.0001, OR = 4.045), but not MRSA colonization (p = 0.128). In the SCD group, the significant predictors of S. aureus carriage were increasing age (p = 0.003; OR = 1.275) and living in self-contained apartments (p = 0.033; OR = 3.632), whereas male gender (p = 0.018; OR = 0.344) and the practice of self-medication (p = 0.039; OR = 0.233) were protective of S. aureus carriage. In the control group, a history of hospitalization in the past year was a risk factor for the carriage of S. aureus (p = 0.048; OR = 14.333). Among the participants of the SCD and control groups, respectively, the resistance prevalence recorded by S. aureus against the various antibiotics investigated were penicillin (100% each), cotrimoxazole (27.5% vs. 20%), tetracycline (25% vs. 50%), rifampicin (82.5% vs. 50%), erythromycin (30% vs. 20%), clindamycin (32.5% vs. 50%), gentamicin (7.5% vs. 20%), cefoxitin (27.5% vs. 20%), linezolid (30% vs. 40%), and fusidic acid (95% vs. 80%). The proportion of S. aureus isolates that were multidrug resistant (MDR) was 92.5% (37/40) in the SCD group and 100% (10/10) in the control group.

Methicillin-resistant Staphylococcus aureus nasal colonization among HIV-infected patients in Taiwan: prevalence, molecular characteristics and associated factors with nasal carriage

Background

To evaluate nasal carriage, antibiotic susceptibility and molecular characteristics of methicillin-resistant Staphylococcus aureus (MRSA), as well as the risk factors of MRSA colonization, in human immunodeficiency virus (HIV)-infected patients in northern Taiwan.

Methods

From September 2014 to November 2015, HIV-infected patients seeking outpatient care at four hospitals were eligible for this study. A nasal specimen was obtained from each subject for the detection of S. aureus and a questionnaire was completed by each subject. MRSA isolates once identified were characterized.

Results

Of 553 patients surveyed, methicillin-susceptible S. aureus (MSSA) was detected in 119 subjects (21.5%) and MRSA in 19 subjects (3.4%). Female gender, injection drug use, smoking, hepatitis C virus carrier, cancer and antibiotic use within 1 year were positively associated with MRSA colonization. By multivariate analysis, only cancer (adjust odds ratio (aOR) 7.78, [95% confidence interval (CI), 1.909–31.731]) and antibiotic use within 1 year (aOR 3.89, [95% CI, 1.219–12.433]) were significantly associated with MRSA colonization. Ten isolates were characterized as sequence type (ST) 59/staphylococcal chromosome cassette (SCC) IV or V_T, endemic community strains in Taiwan, four isolates as ST 8/SCCmec IV (USA 300) and one isolate as ST 239/SCCmec IIIA, a hospital strain. All the community-associated MRSA isolates were susceptible to trimethoprim-sulfamethoxazole (TMP-SMX).

Conclusions

Nasal MRSA carriage in HIV-infected patients seeking outpatient care was low (3.4%) in northern Taiwan. Most of the colonizing isolates were genetically endemic community strains and exhibited high susceptibility to TMP-SMX and fluoroquinolones. Cancer and antibiotic use within 1 year were associated with MRSA colonization.

Intersection of HIV and community-associated methicillin-resistant Staphylococcus aureus

The epidemiology of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has evolved over the past approximately 20 years, with certain populations appearing to have disproportionate risk. Of concern is the potential worsening of S. aureus infections in light of the continued opioid crisis. This review will discuss how CA-MRSA has significantly impacted HIV-infected individuals and address additional factors and populations that are associated with increased risk for MRSA. It will review therapeutic options and infection control strategies as well as highlight how whole genome sequencing can be used to extend traditional epidemiologic analysis and ultimately, inform infection prevention efforts. Continued work identifying those at the highest risk for MRSA, what the best infection prevention settings are in community settings and how to effectively implement and target these strategies is needed. Ultimately, infection control efforts will likely need to extend beyond healthcare settings to effectively and sustainably reduce MRSA infections.

Clonal clusters and virulence factors of methicillin-resistant Staphylococcus Aureus: Evidence for community-acquired methicillin-resistant Staphylococcus Aureus infiltration into hospital settings in Chennai, South India

Background and Objective

Staphylococcus aureus is one of the major pathogens of nosocomial infections as wells as community-acquired (CA) infections worldwide. So far, large-scale comprehensive molecular and epidemiological characterisation of S. aureus from very diverse settings has not been carried out in India. The objective of this study is to evaluate the molecular, epidemiological and virulence characteristics of S. aureus in both community and hospital settings in Chennai, southern India.

Methods

S. aureus isolates were obtained from four different groups (a) healthy individuals from closed community settings, (b) inpatients from hospitals, (c) outpatients from hospitals, representing isolates of hospital-community interface and (d) HIV-infected patients to define isolates associated with the immunocompromised. Antibiotic susceptibility testing, multiplex polymerase chain reactions for detection of virulence and resistance determinants, molecular typing including Staphylococcal cassette chromosome mec (SCCmec) and agr typing, were carried out. Sequencing-based typing was done using spa and multilocus sequence typing (MLST) methods. Clonal complexes (CC) of hospital and CA methicillin-resistant S. aureus (MRSA) were identified and compared for virulence and resistance.

Results and Conclusion

A total of 769 isolates of S. aureus isolates were studied. The prevalence of MRSA was found to be 7.17%, 81.67%, 58.33% and 22.85% for groups a, b, c and d, respectively. Of the four SCCmec types (I, III, IV and V) detected, SCCmec V was found to be predominant. Panton-Valentine leucocidin toxin genes were detected among MRSA isolates harbouring SCCmec IV and V. A total of 78 spa types were detected, t657 being the most prevalent. 13 MLST types belonging to 9 CC were detected. CC1 (ST-772, ST-1) and CC8 (ST238, ST368 and ST1208) were found to be predominant among MRSA. CA-MRSA isolates with SCCmec IV and V were isolated from all study groups including hospitalised patients and were found to be similar by molecular tools. This shows that CA MRSA has probably infiltrated into the hospital settings.

Quantifying the transmission dynamics of MRSA in the community and healthcare settings in a low-prevalence country

Methicillin-resistant Staphylococcus aureus (MRSA), traditionally associated with hospitals, is increasingly circulating in the community. This imposes, in turn, a potential burden on hospital infection control due to a more frequent hospitalization of colonized patients. We developed an individual-based model, reproducing community and healthcare settings, to understand the epidemiological drivers of MRSA and the connections between the society and the healthcare institutions. We show that in Norway, a low-prevalence country, the rise of infections is driven by an increasing inflow of cases from abroad rather than by an ongoing epidemic. We demonstrate the major role played by households in transmitting MRSA and show that the burden on hospitals from the growing community circulation is still limited thanks to aggressive infection-control protocols.

Methicillin-resistant Staphylococcus aureus (MRSA) is a primarily nosocomial pathogen that, in recent years, has increasingly spread to the general population. The rising prevalence of MRSA in the community implies more frequent introductions in healthcare settings that could jeopardize the effectiveness of infection-control procedures. To investigate the epidemiological dynamics of MRSA in a low-prevalence country, we developed an individual-based model (IBM) reproducing the population’s sociodemography, explicitly representing households, hospitals, and nursing homes. The model was calibrated to surveillance data from the Norwegian national registry (2008–2015) and to published household prevalence data. We estimated an effective reproductive number of 0.68 (95% CI 0.47–0.90), suggesting that the observed rise in MRSA infections is not due to an ongoing epidemic but driven by more frequent acquisitions abroad. As a result of MRSA importations, an almost twofold increase in the prevalence of carriage was estimated over the study period, in 2015 reaching a value of 0.37% (0.25–0.54%) in the community and 1.11% (0.79–1.59%) in hospitalized patients. Household transmission accounted for half of new MRSA acquisitions, indicating this setting as a potential target for preventive strategies. However, nosocomial acquisition was still the primary source of symptomatic disease, which reinforces the importance of hospital-based transmission control. Although our results indicate little reason for concern about MRSA transmission in low-prevalence settings in the immediate future, the increases in importation and global circulation highlight the need for coordinated initiatives to reduce the spread of antibiotic resistance worldwide.

Effects of Sexual Network Connectivity and Antimicrobial Drug Use on Antimicrobial Resistance in Neisseria gonorrhoeae

Contemporary strategies to curtail the emergence of antimicrobial resistance in Neisseria gonorrhoeae include screening for and treating asymptomatic infections in high-prevalence populations in whom antimicrobial drug–resistant infections have typically emerged. We argue that antimicrobial resistance in these groups is driven by a combination of dense sexual network connectivity and antimicrobial drug exposure (for example, through screen-and-treat strategies for asymptomatic N. gonorrhoeae infection). Sexual network connectivity sustains a high-equilibrium prevalence of N. gonorrhoeae and increases likelihood of reinfection, whereas antimicrobial drug exposure results in selection pressure for reinfecting N. gonorrhoeae strains to acquire antimicrobial resistance genes from commensal pharyngeal or rectal flora. We propose study designs to test this hypothesis.

Colonization of HIV-Infected Children with Methicillin-Resistant Staphylococcus aureus

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) poses a public health threat owing to its extensive resistance to antibiotics, association with persistent outbreaks, and markedly increased healthcare costs. Moreover, HIV-infected individuals are at a greater risk for colonization with MRSA, and may act as reservoirs for subsequent transmission to other individuals. In Ghana, little is known about MRSA in relation to at-risk populations, such as HIV-infected children. The aim of this study was to investigate nasal carriage of S. aureus and MRSA among HIV-infected children in Accra, including the prevalence, risk factors and antibiotic resistance.

METHODOLOGY

The study was cross-sectional, and involved 107 children with HIV infection and an equal number of sex- and age group- matched apparently healthy controls recruited from the Princess Marie Louis Children's Hospital in Accra. Nasal swab specimens were collected from the study participants and cultured for bacteria. S. aureus isolates were confirmed by the coagulase test while MRSA was confirmed by PCR of the mecA gene. Antimicrobial susceptibility testing of S. aureus isolates was done by the Kirby Bauer method. A structured questionnaire was used to collect data on demographic, household and clinical features of the study participants. A logistic regression analysis was performed to identify determinants of S. aureus and MRSA carriage among participants of both study groups.

RESULTS

The carriage prevalence of S. aureus and MRSA were 44.9% (48) and 5.6% (6), respectively, among the HIV-infected individuals, and the corresponding values within the control group were 23.4% (25) and 0.9% (1). There was a significant association between HIV infection and S. aureus colonization (p < 0.001), but not MRSA colonization (p = 0.055). The main predictor of S. aureus colonization in both study groups was absence of colonization with coagulase negative staphylococcus (p < 0.001). Furthermore, the main predictor of MRSA colonization was regular hand washing with soap (p = 0.043); this was observed among HIV-infected individuals but not the control group. The proportion of S. aureus isolates that were multidrug resistant was 62.3% (33/53) in the HIV-infected group and 80% (20/25) in the control group (p = 0.192).

CONCLUSIONS

HIV infection is a risk factor for nasal colonization of S. aureus among children in Accra but may not be for MRSA. Both the HIV-infected and uninfected children are reservoirs of multidrug resistant S. aureus. Demographic, household and clinical features appear to have little or no relationship with S. aureus and MRSA colonization in the study children.

The global and regional prevalence, burden, and risk factors for methicillin-resistant Staphylococcus aureus colonization in HIV-infected people: A systematic review and meta-analysis

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is among the most important opportunistic pathogens in HIV+ patients, resulting in considerable morbidity and mortality.

METHODS

The MEDLINE, Scopus, Web of Science, and EMBASE databases were comprehensively searched for studies that investigated the prevalence of MRSA colonization in HIV+ patients. We used a random effects model to calculate pooled prevalence estimates with 95% confidence intervals (CI) and analyzed data based on World Health Organization regions.

RESULTS

Among 9,772 records identified, 69 were included in the meta-analysis, comprising 30,050 HIV+ patients from 21 countries. We estimated the pooled worldwide prevalence of MRSA in people living with HIV to be 7% (95% CI 5%-9%, 1,623/30,050), with the highest prevalence in Southeast Asia (16%, 95% CI 9%-24%) and the region of the Americas (10%; 95% CI 7%-13%) and lowest prevalence in the European region (1%; 95% CI 0%-1%). Globally, we estimated approximately 2,659,000 (95% CI 1,835,000-3,303,000) HIV+ patients with colonized MRSA. Potential risk factors for MRSA colonization in HIV+ patients included previous MRSA infection (OR, 7.5; 95% CI, 3.91-14.37), hospitalization in the past year (OR, 1.87; 95% CI 1.11-3.16), and use of antibiotics (OR, 2.52; 95% CI 1.39-4.58).

CONCLUSIONS

Our findings emphasize the importance of routine screening for MRSA among all HIV+ patients throughout the world, especially in regions that have a high burden of disease.

Increased Endovascular Staphylococcus aureus Inoculum Is the Link Between Elevated Serum Interleukin 10 Concentrations and Mortality in Patients With Bacteremia

Background

Cell wall peptidoglycan stimulates interleukin 10 (IL-10) production in Staphylococcus aureus bacteremia (SaB) animal models, but clinical data are not available. This study evaluates the impact of intravascular bacterial cell numbers (ie, the level of bacteremia), in patients at the time of clinical presentation on IL-10 production and its association with S. aureus bacteremia (SaB) mortality.

Methods

Blood and isolates were collected in 133 consecutive SaB patients. Serum IL-10 was quantified by an electrochemoluminescence assay. Bacterial inoculum was measured in patient sera with elevated (n = 8) or low (n = 8) IL-10 using a magnetic bacterial capture assay. Staphylococcus aureus from these 2 groups were introduced into whole blood ex vivo to determine IL-10 production with variable inocula.

Results

IL-10 serum concentration was higher in SaB patient mortality (n = 27) vs survival (n = 106) (median, 36.0 pg/mL vs 10.4 pg/mL, respectively, P < .001). Patients with elevated IL-10 more often had endovascular SaB sources. The inoculum level of SaB was higher in patients with elevated serum IL-10 vs patients with low IL-10 (35.5 vs 0.5 median CFU/mL; P = .044). Ex vivo studies showed that 108 CFU/mL yielded greater IL-10 than did 103 CFU/mL (4.4 ± 1.8 vs 1.0 ± 0.6 pg/mL; P < .01).

Conclusions

Elevated IL-10 serum concentrations at clinical presentation of SaB were highly associated with mortality. High intravascular peptidoglycan concentration, driven by a higher level of bacteremia, is a key mediator of IL-10 anti-inflammatory response that portends poor clinical outcome. Using IL-10 as an initial biomarker, clinicians may consider more aggressive antimicrobials for rapid bacterial load reduction in high-risk SaB patients.

Methodologic considerations of household-level methicillin-resistant Staphylococcus aureus decolonization among persons living with HIV

BACKGROUND

People living with HIV (PLWH) have a higher prevalence of methicillin-resistant Staphylococcus aureus (MRSA) colonization and likelihood of recurrent infection than the general population. Simultaneously treating MRSA-colonized household members may improve success with MRSA decolonization strategies. This article describes a pilot trial testing household-level MRSA decolonization and documents methodologic and pragmatic challenges of this approach.

METHODS

We conducted a randomized controlled trial of individual versus individual-plus-household MRSA decolonization to reduce recurrent MRSA. PLWH with a history of MRSA who are patients of an urban HIV clinic received a standard MRSA decolonization regimen. MRSA colonization at 6 months was the primary outcome.

RESULTS

One hundred sixty-six patients were referred for MRSA screening; 77 (46%) enrolled. Of those, 28 (36%) were colonized with MRSA and identified risk factors consistent with the published literature. Eighteen were randomized and 13 households completed the study.

CONCLUSIONS

This is the first study to report on a household-level MRSA decolonization among PLWH. Challenges included provider referral, HIV stigma, confidentiality concerns over enrolling households, and dynamic living situations. Although simultaneous household MRSA decolonization may reduce recolonization, recruitment and retention challenges specific to PLWH limit the ability to conduct household-level research. Efforts to minimize these barriers are needed to inform evidence-based practice.

Genomic and Epidemiological Evidence for Community Origins of Hospital-Onset Methicillin-Resistant Staphylococcus aureus Bloodstream Infections

Background

We examined whether disparities existed in hospital-onset (HO) Staphylococcus aureus bloodstream infections (BSIs) and used whole-genome sequencing (WGS) to identify factors associated with USA300 transmission networks.

Methods

We evaluated HO methicillin-susceptible S. aureus (MSSA) and HO methicillin-resistant S. aureus (MRSA) BSIs for 2009-2013 at 2 hospitals and used an adjusted incidence for modeling. WGS and phylogenetic analyses were performed on a sample of USA300 BSI isolates. Epidemiologic data were analyzed in the context of phylogenetic reconstructions.

Results

On multivariate analysis, male sex, African-American race, and non-Hispanic white race/ethnicity were significantly associated with HO-MRSA BSIs whereas Hispanic ethnicity was negatively associated (rate ratio, 0.41; P = .002). Intermixing of community-onset and HO-USA300 strains on the phylogenetic tree indicates that these strains derive from a common pool. African-American race was the only factor associated with genomic clustering of isolates.

Conclusions

In a multicenter assessment of HO-S. aureus BSIs, African-American race was significantly associated with HO-MRSA but not MSSA BSIs. There appears to be a nexus of USA300 community and hospital transmission networks, with a community factor being the primary driver. Our data suggest that HO-USA300 BSIs likely are due to colonizing strains acquired in the community before hospitalization. Therefore, prevention efforts may need to extend to the community for maximal benefit.

Epidemiology and clinical relevance of Staphylococcus aureus intestinal carriage: a systematic review and meta-analysis

INTRODUCTION

Recent data highlight the importance of screening more than one site for improving the detection of S. aureus colonization. Intestinal carriage is frequently under-investigated and its clinical impact ought to be defined a better way. Areas covered: This review and meta-analysis provide an updated overview of prevalence, characteristics and clinical significance of S. aureus intestinal carriage in different populations, both for methicillin-susceptible and -resistant S. aureus strains. Expert commentary: Intestinal S. aureus carriage is documented with higher prevalence in children and in patients with S. aureus skin and soft tissue infections. This site of colonization was shown to be associated with a high risk of dissemination in the environment and with S. aureus infection. Intestinal carriage is frequently retrieved in nasal carriers, reflecting probably an association with a high bacterial load. Exclusive intestinal carriage present in one third of intestinal carriers can be associated with infection. Comparative genotyping analysis of different strains from nasal and extra-nasal sites of carriage, including the intestinal ones, in the same individuals, would allow a better comprehension of the pathophysiology of S. aureus endogenous infection. It could also permit to improve the prevention of these infections by decolonization of sites implicated in infection genesis.

Prevalence of and risk factors for methicillin-resistant Staphylococcus aureus colonization among human immunodeficient virus-infected outpatients in Taiwan: oral Candida colonization as a comparator

Human immuodeficency virus (HIV)-infected patients receiving highly active antiretroviral therapy (HAART) and community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) have increased in recent years in Taiwan. This study was undertaken to determine the prevalence of and risk factors for nasal and oral S. aureus and MRSA colonization among contemporary HIV-infected populations. Clinical variables for S. aureus and MRSA colonization among HIV-infected outpatients from three hospitals were analyzed and compared with those for oral Candida colonization. Genetic characteristics of MRSA isolates were analyzed. A total of 714 patients were screened for nasal S. aureus colonization, and a subset of 457 patients were also screened for oral S. aureus colonization. Of all patients, 79.4% were receiving HAART, and their mean CD4 count was 472 cells/mm³. The colonization rates in the oral cavity, nasal cavity, and at either site were 18.8%, 31.7%, and 36.8%, respectively, for S. aureus, and 3.1%, 4.4%, and 5.5%, respectively, for MRSA. These rates were all much lower than the previously reported rate of oral Candida colonization (52.4%). By multivariate analysis, a suppressed viral load (<200 copies/mL) protected against oral S. aureus, MRSA, and Candida colonization, and recent use of antibacterial agents protected against oral and nasal S. aureus colonization. Recent incarceration increased the risk of nasal MRSA colonization, while recent hospitalization, tuberculosis, older age, and intravenous drug use increased the risk of oral Candida colonization. Candida spp. did not augment S. aureus or MRSA colonization in the oral cavity. Most of the 41 MRSA isolates recovered belonged to the SCCmec IV/pvl-negative (51.2%) and V_T/pvl-positive (26.8%) ST59 local prevalent CA-MRSA clones. Distinct carriage rates demonstrated here suggested that mucosal immunity against colonization might differ in terms of microbes and sites. A decreased risk in oral carriage of MRSA and Candida might be a benefit of HAART.

Whole Genome Sequencing-Implications for Infection Prevention and Outbreak Investigations

PURPOSE OF REVIEW

Whole genome sequencing (WGS) is a laboratory method that has emerged as a promising tool for epidemiologic investigations.

RECENT FINDINGS

Genomic epidemiology approaches have been utilized in outbreak settings, community settings, within acute care hospitals, and across healthcare facilities to better understand transmission and spread of potential pathogens. These studies have highlighted how essential robust epidemiologic data is in these analyses as well as how results can be translated into clinical practice and infection control and prevention. Existing studies have highlighted both the promise and challenges of using WGS as an epidemiologic tool in a community and healthcare setting and across a region. Costs for performing and interpreting WGS analyses are decreasing, and availability of and experience with WGS analyses in healthcare epidemiology are increasing. With these favorable trends, this laboratory method soon could emerge as the gold standard for epidemiologic evaluations.

Staphylococcus epidermidis Protection Against Staphylococcus aureus Colonization in People Living With Human Immunodeficiency Virus in an Inner-City Outpatient Population: A Cross-Sectional Study

Background.

People living with human immunodeficiency virus (PLWH) have been disproportionally affected by methicillin-resistant Staphylococcus aureus (MRSA) colonization and infection, in particular by clones USA300 and USA500. However, the contribution of epidemiological, bacterial, and immunological risk factors to the excess of S aureus in PLWH remain incompletely understood.

Methods.

In this cross-sectional study, we determined the prevalence and molecular epidemiology of S aureus colonization in 93 PLWH attending an urban human immunodeficiency virus (HIV) clinic. Participants completed a structured interview assessing demographic information and risk factors for MRSA. Swabs were obtained from the nose, throat, and groin and cultured for S aureus and Staphylococcus epidermidis.

Results.

Most participants had well controlled HIV infection (89, 96% CD4 >200). Thirty-six (39%) individuals were colonized with S aureus at 1 or more body sites, including 6 (6%) with MRSA. Regular gym use was a risk factor for S aureus but not MRSA carriage. In contrast, S epidermidis was present in almost all individuals (n = 84, 90%), predominantly in the nares (n = 66, 71%). Using generalized estimating equation models, we observed that the odds of S aureus colonization were significantly and drastically reduced when S epidermidis was detected (P = .0001). After controlling for site, gender, and age, we identified that the odds of S aureus colonization were 80% less if S epidermidis was present (adjusted odds ratio, 0.20; 95% confidence interval, .09–.45; P < .0001).

Conclusions.

Taken together, we observed a lower prevalence of S aureus and MRSA colonization than has been previously reported in PLWH. In this cohort, colonization with S epidermidis was protective against S aureus colonization.

The complex relationship between CD4 count, HIV viral load, trimethoprim-sulfamethoxazole prophylaxis, and skin-and-soft-tissue infection risk in patients with HIV: insights from a causal diagram and simulation study

Skin and soft tissue infection (SSTIs) due to Staphylococcus aureus, particularly community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA), are common in human immunodeficiency virus (HIV)-infected populations in the United States. Studies have differed as to the importance of epidemiological and immunological factors in this relationship, and have employed conflicting strategies for variable selection in multivariate analyses. Developments in causal inference methods in epidemiology have emerged in the last decade to clarify relationships between variables and identify appropriate variables to include in and exclude from multivariate analysis. In this paper, we develop a causal diagram to clarify the pathways linking CA-MRSA and HIV. We focus on the role played by trimethoprim-sulfamethoxazole (TMP-SMX) prophylaxis, prescribed to many severely immunocompromised HIV patients and potentially protective against SSTIs, which both mediates and moderates the relationship between immunological parameters and SSTI risk. We demonstrate, using simulated data, that statistical models may yield biased results if they do not account for how HIV viral load may also be a marker of adherence to TMP-SMX prophylaxis. We conclude with a proposed causal model that includes both the epidemiological as well as immunological factors that may explain the increased risk of initial and recurrent SSTI risk in HIV-infected populations.

Living Conditions as a Driving Factor in Persistent Methicillin-resistant Staphylococcus aureus Colonization Among HIV-infected Youth

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) colonization has been linked to HIV-related sexual and social behaviors. MRSA risk factors may be different for HIV-infected children, adolescents and young adults. We investigated the association of MRSA colonization, persistent colonization and genotypes with potential risk factors among HIV-infected youth.

METHODS

For this case-control study, patients 24 years of age or younger attending 2 HIV reference centers were recruited from February to August 2012 and followed for 1 year. Nasal swabs were collected at enrollment and every 3 months. MRSA clones were characterized by staphylococcal chromosomal cassette mec typing, spa typing and multilocus sequence typing. We compared MRSA colonization and persistent colonization with patient demographic and clinical characteristics.

RESULTS

Among 117 participants, MRSA colonization frequency (calculated for each collection based on the number of positive cultures per patient) was 12.8% at the first collection. The average MRSA colonization frequency was 10.4%. Our results showed 11.1% were persistent carriers (subjects with more than 1 positive culture in at least 3). Crowding was the only factor associated with MRSA colonization (P = 0.018). Persistent carriers had significantly higher (4.2 times) odds of living in a crowded household (95% confidence interval-1.1-16.2). We observed high genetic diversity among MRSA isolates, with t002/ST5 and t318/ST30 being the most frequent.

CONCLUSIONS

MRSA colonization among HIV-infected youth is more closely related to living in a low-income or slum community than to HIV-related clinical factors. High genetic MRSA isolate diversity in our population suggests frequent transmission.

HIV and colonization with Staphylococcus aureus in two maximum-security prisons in New York State

OBJECTIVE

To evaluate the association between HIV and Staphylococcus aureus colonization after confounding by incarceration is removed.

METHOD

A cross sectional stratified study of all HIV infected and a random sample of HIV-uninfected inmates from two maximum-security prisons in New York State. Structured interviews were conducted. Anterior nares and oropharyngeal samples were cultured and S. aureus isolates were characterized. Log-binomial regression was used to assess the association between HIV and S. aureus colonization of the anterior nares and/or oropharynx and exclusive oropharynx colonization. Differences in S. aureus strain diversity between HIV-infected and uninfected individuals were assessed using Simpson's Index of Diversity.

RESULTS

Among 117 HIV infected and 351 HIV uninfected individuals assessed, 47% were colonized with S. aureus and 6% were colonized with methicillin resistant S. aureus. The prevalence of S. aureus colonization did not differ by HIV status (PR = 0.99, 95% CI = 0.76-1.24). HIV infected inmates were less likely to be exclusively colonized in the oropharynx (PR = 0.55, 95% CI = 0.30-0.99). Spa types t571 and t064 were both more prevalent among HIV infected individuals, however, strain diversity was similar in HIV infected and uninfected inmates.

CONCLUSIONS

HIV infection was not associated with S. aureus colonization in these maximum-security prison populations, but was associated with decreased likelihood of oropharyngeal colonization. Factors that influence colonization site require further evaluation.

A cross sectional study of animal and human colonization with Methicillin-Resistant Staphylococcus aureus (MRSA) in an Aboriginal community

Background

Methicillin-resistant Staphylococcus aureus (MRSA) infections are common among humans in Aboriginal communities in Canada, for unknown reasons.

Methods

Cross sectional study of humans and dogs in an Aboriginal community of approximately 1200 persons. Our objectives were to measure community-based prevalence of nasal MRSA colonization among humans, use multivariable logistic regression to analyze risk factors for MRSA colonization, and perform molecular typing of Staphylococci isolated to investigate interspecies transmission.

Results

461 humans were approached for consent and 442 provided complete data. 109/442 (24.7 %, 95 % C.I. = 20.7–28.7 %) of humans were colonized with MRSA. 169/442 (38.2 %) of humans had received antibiotics in the last 12 months. Only number of rooms in the house (OR 0.86, p = 0.023) and recreational dog use (OR 7.7, p = 0.002) were significant risk factors for MRSA colonization. 95/109 (87.1 %) of MRSA strains from humans were of the same spa type (CMRSA10/USA300). 8/157 (5.1 %, 95 % C.I. = 1.7–8.5 %) of dogs were colonized with methicillin-susceptible S. aureus, and no dogs were colonized with MRSA.

Conclusions

Human MRSA colonization in this community is very common, and a single clone is predominant, suggesting local transmission. Antibiotic use is also very common. Crowding may partially explain high colonization, but most considered risk factors including animal exposure were not predictive. Very few dogs carried human Staphylococcal strains.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-016-3220-9) contains supplementary material, which is available to authorized users.

Strategies to Prevent Methicillin-ResistantStaphylococcus aureusTransmission and Infection in Acute Care Hospitals: 2014 Update

Previously published guidelines are available that provide comprehensive recommendations for detecting and preventing healthcare-associated infections (HAIs). The intent of this document is to highlight practical recommendations in a concise format designed to assist acute care hospitals in implementing and prioritizing their methicillin-resistantStaphylococcus aureus(MRSA) prevention efforts. This document updates “Strategies to Prevent Transmission of Methicillin-ResistantStaphylococcus aureusin Acute Care Hospitals,” published in 2008. This expert guidance document is sponsored by the Society for Healthcare Epidemiology of America (SHEA) and is the product of a collaborative effort led by SHEA, the Infectious Diseases Society of America (IDSA), the American Hospital Association (AHA), the Association for Professionals in Infection Control and Epidemiology (APIC), and The Joint Commission, with major contributions from representatives of a number of organizations and societies with content expertise. The list of endorsing and supporting organizations is presented in the introduction to the 2014 updates.

Genomic Epidemiology of USA300 Methicillin-Resistant Staphylococcus aureus in an Urban Community

BACKGROUND

In a community, it is unknown what factors account for transmission of methicillin-resistant Staphylococcus aureus (MRSA). We integrated whole genome sequencing (WGS) and epidemiologic data to identify factors associated with MRSA transmission networks in an urban community.

METHODS

WGS was performed on colonizing USA300 MRSA isolates from 74 individuals within 72 hours of admission to a public hospital in Chicago, IL. Single nucleotide variants (SNVs) were used to reconstruct the phylogeny of sequenced isolates, and epidemiologic data was overlaid to identify factors associated with transmission networks.

RESULTS

The maximum within-patient SNV difference for an individual with multisite colonization was 41 SNVs, with no systematic divergence among body sites. We observed a minimum of 7 SNVs and maximum of 153 SNVs between isolates from different individuals. We identified 4 pairs of individuals whose isolates were within 40 SNVs of each other. Putting our isolates in the context of previously sequenced USA300 isolates from other communities, we identified a 13-member group and two 4-member groups that represent samples from putative local transmission networks. Individuals in these groups were more likely to be African American, to be human immunodeficiency virus-infected, to reside in high detainee release areas, and to be current users of illicit drugs.

CONCLUSIONS

Using WGS, we observed potential transmission networks in an urban community and that certain epidemiologic factors were associated with inclusion in these networks. Future work with contact tracing and advanced molecular diagnostics may allow for identification of MRSA "epicenters" in the community where interventions can be targeted.

Housing Status, Medical Care, and Health Outcomes Among People Living With HIV/AIDS: A Systematic Review

BACKGROUND

Accumulating evidence suggests responses to HIV that combine individual-level interventions with those that address structural or contextual factors that influence risks and health outcomes of infection. Housing is such a factor. Housing occupies a strategic position as an intermediate structural factor, linking "upstream" economic, social, and cultural determinants to the more immediate physical and social environments in which everyday life is lived. The importance of housing status for HIV prevention and care has been recognized, but much of this attention has focused on homeless individuals as a special risk group. Analyses have less often addressed community housing availability and conditions as factors influencing population health or unstable, inadequate, or unaffordable housing as a situation or temporary state. A focus on individual-level characteristics associated with literal homelessness glosses over social, economic, and policy drivers operating largely outside any specific individual's control that affect housing and residential environments and the health resources or risk exposures such contexts provide.

OBJECTIVES

We examined the available empirical evidence on the association between housing status (broadly defined), medical care, and health outcomes among people with HIV and analyzed results to inform future research, program development, and policy implementation.

SEARCH METHODS

We searched 8 electronic health and social science databases from January 1, 1996, through March 31, 2014, using search terms related to housing, dwelling, and living arrangements and HIV and AIDS. We contacted experts for additional literature.

SELECTION CRITERIA

We selected articles if they were quantitative analyses published in English, French, or Spanish that included at least 1 measure of housing status as an independent variable and at least 1 health status, health care, treatment adherence, or risk behavior outcome among people with HIV in high-income countries. We defined housing status to include consideration of material or social dimensions of housing adequacy, stability, and security of tenure.

DATA COLLECTION AND ANALYSIS

Two independent reviewers performed data extraction and quality appraisal. We used the Cochrane Risk of Bias Tool for randomized controlled trials and a modified version of the Newcastle Ottawa Quality Appraisal Tool for nonintervention studies. In our quality appraisal, we focused on issues of quality for observational studies: appropriate methods for determining exposure and measuring outcomes and methods to control confounding.

RESULTS

Searches yielded 5528 references from which we included 152 studies, representing 139,757 HIV-positive participants. Most studies were conducted in the United States and Canada. Studies examined access and utilization of HIV medical care, adherence to antiretroviral medications, HIV clinical outcomes, other health outcomes, emergency department and inpatient utilization, and sex and drug risk behaviors. With rare exceptions, across studies in all domains, worse housing status was independently associated with worse outcomes, controlling for a range of individual patient and care system characteristics.

CONCLUSIONS

Lack of stable, secure, adequate housing is a significant barrier to consistent and appropriate HIV medical care, access and adherence to antiretroviral medications, sustained viral suppression, and risk of forward transmission. Studies that examined the history of homelessness or problematic housing years before outcome assessment were least likely to find negative outcomes, homelessness being a potentially modifiable contextual factor. Randomized controlled trials and observational studies indicate an independent effect of housing assistance on improved outcomes for formerly homeless or inadequately housed people with HIV. Housing challenges result from complex interactions between individual vulnerabilities and broader economic, political, and legal structural determinants of health. The broad structural processes sustaining social exclusion and inequality seem beyond the immediate reach of HIV interventions, but changing housing and residential environments is both possible and promising.