Nasal Colonization Research Articles

2315. Impact of MSSA Surveillance and Decolonization on Invasive Infection in the Neonatal ICU

Abstract Background Invasive methicillin-susceptible Staphylococcus aureus (MSSA) infections are an important cause of morbidity and mortality in neonatal intensive care unit (NICU) infants. MSSA colonization (asymptomatic carriage in the nose, skin, or gut) is a risk factor for subsequent invasive infection (e.g., pneumonia, bone infections, bloodstream infections, etc). Active surveillance programs coupled with decolonization measures for MSSA-colonized infants have been associated with decreased invasive MSSA infection rates in the NICU setting. Methods In June 2020, an active surveillance program was implemented to detect MSSA nasal colonization for infants admitted to the St. Louis Children’s Hospital NICU, a 140-bed quaternary NICU. MSSA-colonized infants were decolonized with a 7 day course of intranasal mupirocin twice daily plus topical chlorhexidine baths on days 1, 4, and 7 (for infants greater than 30 weeks postmenstrual age). MSSA bloodstream infection (BSI) rates were followed quarterly pre- (September 2018-May 2020) and post- (June 2020-March 2022) implementation of MSSA surveillance and decolonization. Mean MSSA BSI rates pre- and post-implementation were compared via paired T-test. The number of infants treated with mupirocin was calculated pre- and post-implementation. Results After implementing MSSA surveillance and decolonization there was no significant change in the mean MSSA BSI rate (Figure): 0.22 per 1000 patient-days pre-implementation, 0.16 per 1000 patient-days post-implementation (p=0.37). Since initiating MSSA decolonization in June 2020, the number of NICU infants exposed to mupirocin increased nearly fourfold: mean 10 infants treated per month pre-implementation, mean 38 infants treated per month post-implementation. Conclusion Implementing an MSSA surveillance and decolonization program in the NICU was not associated with a sustained decrease in invasive MSSA infections. However, mupirocin use in the NICU nearly quadrupled following implementation. Additional investigation is warranted to identify potential contributing factors for unchanged invasive MSSA infection rates despite active surveillance and decolonization (e.g., emerging mupirocin resistance). Disclosures All Authors: No reported disclosures.

204. Genomic comparison of blood and colonizing nasal isolates in patients hospitalized with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia

Abstract Background Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of health-care associated infections, particularly bloodstream infections (BSI). Concomitant colonization of the anterior nares has been shown to have implications on persistence, recurrence, and transmission events. We performed genomic comparisons between paired nasal and blood MRSA isolates obtained from the same patient to elucidate the genetic differences that may contribute to within-host invasion and virulence. Methods Patients hospitalized with MRSA bloodstream infection were swabbed in the bilateral nares. Paired blood and nasal isolates underwent DNA extraction and spa typing. Nasal and blood isolates from the same patients with matching spa types were sequenced by Illumina and PacBio respectively. For genomic analysis, PathoSPOT and Snippy were used to compare genomes of nasal and blood isolate pairs to evaluate single nucleotide polymorphisms, insertions and deletions. Results Of 121 patients with MRSA BSI, 87 patients (72%) had concomitant colonization of the anterior nares with MRSA. Spa type of t002 predominated in both blood and nasal isolates. From the 76 pairs that underwent genomic analysis, several mutated genes were identified across all pairwise comparisons, 8 of which recurred in more than one patient pair. These included genes involved in conferring antibiotic resistance, increased mutability, immune evasion, and adaptive metabolism. Conclusion In patients with MRSA BSI and concomitant MRSA nasal colonization, mutations identified by genomic analysis in blood-nasal pairs are implicated in contributing to invasion and within-host adaptability. Disclosures All Authors: No reported disclosures.

Interventions for the eradication of meticillin-resistant Staphylococcus aureus (MRSA) in people with cystic fibrosis.

Interventions for the eradication of meticillin-resistant Staphylococcus aureus (MRSA) in people with cystic fibrosis.

The Potential Threat of Vertical Transmission in Methicillin-Resistant Staphylococcus Aureus Infection: A Systematic Review 2022.

This systematic review paper aimed to assess and analyze the prevalence of maternal colonization of Staphylococcus aureus (S. aureus) also known as methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) in the peripartum period and its significance on vertical transmission to the neonate and if it is a potential threat to the health of newborns. For this, multiple databases, such as PubMed, MEDLINE, ScienceDirect, and the database of Elsevier, were used to scout for relevant articles, and results were reported adhering to the principles set by Preferred Items for Systematic reviews and Meta-Analysis (PRISMA) guidelines 2020. A specific medical subject headings (MeSH) criterion was designed to search for relevant publications on PubMed. A total of 26 articles were finally selected after a meticulous screening process, including detailed inclusion and exclusion criteria, manual reading of titles and abstracts, and availability of accessible full-text articles. A few articles were also selected after going through the citations section of the initially selected papers. Quality appraisal was done on the selected publications. Maternal colonization of S. aureus is determined to be highly prevalentwith the hypothesis that nasal colonization had higher rates than recto-vaginal sites. Increasing maternal age, history of vaginitis, and multiparity were the most common risk factors for MRSA and MSSA colonization. Premature babies were at the highest risk of MRSA colonization. Breast milk is also a risk factor for neonatal MRSA transmission. Through this systematic review, we concluded that although the rate of vertical transmission of MRSA is lower than that of MSSA, we felt that it held significance as neonates with the bug have poor outcomes due to skin and soft tissue infections and there is spread of MRSA to other neonates in the wardsand spread to siblings in cases of triplets and quadruplets and even death due to potential MRSA sepsis. Women in Africa and China had high prevalence rates of MRSA and S. aureus which can probably be attributed to a lack of access to adequate healthcare facilities. We recommend screening with regular recto-vaginal swabs and nasal swabs especially in regions with a high burden of MRSA to be performed at regular intervals after confirmation of pregnancy, as prevention and screening are effective to avoid serious complications.

Prevalence and Antibiotic-Resistant Profiles of Staphylococci Nasal Colonization in Nursing Home Residents

Prevalence and Antibiotic-Resistant Profiles of Staphylococci Nasal Colonization in Nursing Home Residents

Effects of preoperative Staphylococcus aureus screening and targeted decolonization bundle protocols in cardiac surgery: a nine-year review of a regional cardiovascular center in China.

Nosocomial infection (NI) prolongs hospital stay and heightens mortality among patients who underwent cardiac surgery. We constructed a retrospective study to explore the prevalence of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (SA/MRSA) nasal colonization, as well as the effects of SA/MRSA decolonization bundle measures on SA/MRSA-related infection among Chinese cardiac patients. After reviewing the medical records, we divided cardiovascular surgery patients treated at our central campus into two groups: the baseline group (treated between January 2012 and December 2013) and the intervention group (treated between May 2014 and December 2020). Intervention measures consisted of preoperative nasal screening and targeted decolonization bundle therapy. The medical records of patients at our southern campus (treated between January 2017 and December 2020) were collected as an additional control group, since we did not implement SA intervention measures at this location. The incidences of SA/MRSA-related NI were then compared between the groups. There were 794 patients in the baseline group and 2,826 in the intervention group. A total of 131 (4.6%) patients had SA nasal colonization, and among them, 33 patients (1.2%) were MRSA colonized. SA/MRSA was cleared in approximately 95% of the carriers. The total level of SA-related infection was significantly lower in the intervention group compared to the baseline group [0.354% vs. 1.133%, respectively; P=0.021; risk ratio (RR): 0.312; 95% confidence interval (CI): 0.127-0.766]. The incidence of MRSA-related infection followed the same trend (0.212% vs. 0.756%, respectively; P=0.030; RR: 0.281; 95% CI: 0.091-0.860). When compared to the southern campus, SA intervention measures at the central campus resulted in a significant reduction in total SA-related infection (1.132% vs. 0.284%, respectively; P=0.035; RR: 0.251; 95% CI: 0.077-0.820). The prevalence of SA/MRSA colonization is relatively low among Chinese patients who received cardiovascular surgery. Targeted decolonization bundle therapy was associated with cleared colonization and reduced incidence of SA/MRSA-related infection.

The Rate of Nasal and Oral Colonization and Expression Levels of Hyphal Adhesin Als3p and mecA Genes in Methicillin-Resistant Staphylococcus aureus and Candida spp. Isolated From Patients With Lung Cancer

Background: Patients with cancer is considered highly susceptible group to both nosocomial and community-acquired infections. Objectives: In the present research, we aimed to determine the rate of nasal and oral colonization and expression level of Als3p and mecA genes among Candida spp. and methicillin-resistant Staphylococcus aureus (MRSA) in co-colonization and single colonization conditions. Materials and Methods: In total, 110 oral swab samples and 110 nasal swab samples were gathered from patients with lung cancer. The frequency of MRSA isolates (oxacillin-resistant Staphylococcus aureus) was determined using the disk diffusion method. In addition, the frequency and expression levels of Als3p and mecA genes among MRSA and Candida spp. isolates were determined and compared using PCR and qRT-PCR methods, respectively. Results: Candida spp. and S. aureus were found in 42.7% (n=47/110), and 9.1% (n=10/110) of oral samples, respectively, while Candida spp. and S. aureus were found in 5.5% (n=6/110) and 16.4% (n=18/110) of nasal samples, respectively. Additionally, 55.5% (n=10/18) of S. aureus isolates obtained from nasal samples were MRSA. Candida albicans (n=23/110; 20.9%) had the highest frequency among Candida species. In all MRSA and Candida spp. isolates, the Als3p and mecA gene expression increased two and three times in co-colonization condition compared to single colonization condition, respectively. Conclusion: The present study revealed that co-colonization has a synergistic effect on the expression level of mecA and Als3p genes. Our finding suggested that co-colonization can facilitate the invasion of S. aureus and leads to systemic and severe infections in co-colonized patients.

PREVALENCE OF METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS AND OTHER STAPHYLOCOCCAL NASAL CARRIAGES AMONG HEALTHCARE WORKERS, PHRAMONGKUTKLAO HOSPITAL

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a group of S. aureus strains containing the SCCmec gene causing beta-lactam antibiotic resistance. MRSA is common in healthcare settings and can cause serious problems.
 Objective: The study aimed to investigate the prevalence of MRSA nasal colonization among privates of the Medical Private Company, Phramongkutklao Hospital, including antibiotic susceptibility pattern of S. aureus isolates and risk factors of S. aureus nasal carriage.
 Methods: Nasal swabs were obtained from the anterior nares of 170 privates. Staphylococcal isolates were identified using a catalase test, tube coagulase test and matrix-assisted laser desorption/ ionization time of flight mass spectrometry (MALDI-TOF MS). MRSA detection was screened using cefoxitin disk diffusion and confirmed using the mecA gene detection and SCCmec typing. Antibiotic susceptibility patterns of S. aureus were examined using the disk diffusion method. A questionnaire was collected from the subjects to determine risk factors for S. aureus nasal carriage.
 Results: Of 170 subjects, 157 (92.35%) revealed staphylococcal positive, yielding 161 staphylococcal isolates. The prevalence of MRSA, methicillin-resistant Staphylococcus epidermidis (MRSE), and methicillin-susceptible Staphylococcus aureus (MSSA) nasal carriage was 0.59, 1.18 and 8.82%, respectively. The MRSA isolate carried mecA revealing SCCmec type II. The MSSA isolates indicated low resistance to tetracycline (13.3%), whereas the MRSA isolate resisted ciprofloxacin, clindamycin, erythromycin, gentamicin, oxacillin and tetracycline. Using multiple logistic regression analysis, a significant risk factor for S. aureus nasal carriage was utensil sharing (adjusted odds ratio=4.41; 95% CI=1.33-14.61).
 Conclusion: Healthcare-associated MRSA existed among privates of the Medical Private Company. An associated risk factor for acquiring S. aureus was utensil sharing which could be used to help improve prevention and control management among privates.

Antimicrobial Photodynamic Therapy in the Nasal Decolonization of Maintenance Hemodialysis Patients: A Pilot Randomized Trial

Infections are an important cause of mortality among patients receiving maintenance hemodialysis. Staphylococcus aureus is a frequent etiological agent, and previous nasal colonization is a risk factor for infection. Repeated antimicrobial decolonization reduces infection in this population but can induce antibiotic resistance. We compared photodynamic therapy, a promising bactericidal treatment that does not induce resistance, to mupirocin treatment among nasal carriers of Saureus. Randomized controlled pilot study. 34 patients receiving maintenance hemodialysis who had nasal carriage of S aureus. Patients were randomly assigned to decolonization with a single application of photodynamic therapy (wavelength of 660nm, 400mW/cm2, 300 seconds, methylene blue 0.01%) or with a topical mupirocin regimen (twice a day for 5 days). Nasal swabs were collected at time 0 (when the carrier state was identified), directly after treatment completion, 1 month after treatment, and 3 months after treatment. Bacterial isolates were subjected to proteomic analysis to identify the species present, and antimicrobial susceptibility was characterized. All 17 participants randomized to photodynamic therapy and 13 of 17 (77%) randomized to mupirocin were adherent to treatment. Directly after treatment was completed, 12 participants receiving photodynamic therapy (71%) and 13 participants treated with mupirocin (77%) had cultures that were negative for S aureus (risk ratio, 0.92 [95% CI, 0.61-1.38]; P=0.9). Of the patients who had negative cultures directly after completion of photodynamic therapy, 67% were recolonized within 3 months. There were no adverse events in the photodynamic therapy group. Testing was restricted to assessing nasal colonization; infectious complications were not assessed. Photodynamic therapy is a feasible approach to treating nasal carriage of S aureus. Future larger studies should be conducted to determine whether photodynamic therapy is equivalent to the standard of care with mupirocin. Government grant (National Council for Scientific and Technological Development process 3146682020-9). Registered at ClinicalTrials.gov with study number NCT04047914.

Resultados de un programa de descolonización de Staphylococcus aureus en cirugía protésica primaria de cadera y rodilla

IntroductionDetection and decolonization of Staphylococcus aureus prior to surgery is postulated as an option to reduce the risk of infection in arthroplasties. The aim of this study was to evaluate the effectiveness of a screening program for S. aureus in total knee arthroplasty (TKA) and total hip arthroplasty (THA), the incidence of infection with respect to a historical cohort, and its economic viability. Material and methodsPre-post intervention study in patients undergoing primary knee and hip prostheses in 2021, a protocol was carried out to detect nasal colonization by S. aureus and eradication if appropriate, with intranasal mupirocin, post-treatment culture with results three weeks between post-treatment culture and surgery. Efficacy measures are evaluated, costs are analyzed and the incidence of infection is compared with respect to a historical series of patients operated on between January and December 2019, performing a descriptive and comparative statistical analysis. ResultsThe groups were statistically comparable. Culture was performed in 89%, with 19 (13%) positive patients. Treatment was confirmed in 18, control culture in 14, all decolonized; none suffered infection. One culture-negative patient suffered from Staphylococcus epidermidis infection. In historical cohort: 3 suffered deep infection by S. epidermidis, Enterobacter cloacae, S. aureus. The cost of the program is €1661.85. ConclusionThe screening program detected 89% of the patients. The prevalence of infection in the intervention group was lower than in the cohort, with S. epidermidis being the main microorganism, different from S. aureus described in the literature and in the cohort. We believe that this program is economically viable, as its costs are low and affordable.

The association between antibiotics and community-associated Staphylococcus aureus colonization in the United States population: Analysis of the National Health and Nutrition Examination Survey (NHANES).

Staphylococcus aureus nasal colonization is a seriously opportunistic infection. However, there is a lack of research of relationship between antibiotics and S aureus colonization in the general population. Through a cross-sectional investigation, this study intends to establish the parameters related to S aureus nasal colonization, specifically the function antibiotics play in colonization. The key information from 2001 to 2004 was abstracted from National Health and Nutrition Examination Survey (NHANES), including information on general demographics, health care status, antibiotic prescription, diabetes, alcohol consumption, and tobacco smoke exposure. The participants colonized with methicillin-susceptible S aureus (MSSA), or methicillin-resistant S aureus (MRSA) were defined as the case group, and the control group was subjects without positive S aureus colonization. Univariate and multivariate logistic regression models were used to identify the variables associated with MSSA and MRSA colonization. The records of 18,607 individuals were included, involving 13,205 cases without S aureus colonization, 5195 cases with MSSA, and 207 cases with MRSA. In the multivariate logistic regression analysis, the risk of MSSA colonization was significantly reduced with fluoroquinolone use (75% risk reduction, P = .02), sulfonamide use (98% risk reduction, P < .01), tetracycline use (81% risk reduction, P < .01) and antibiotic combination therapy (risk reduction 76%, P < .01). Female, race and total household size were strongly associated with MSSA carriage. On the other hand, regarding MRSA colonization, fluoroquinolone use, long-term care, and former smoker were positively associated with MRSA colonization, while high income was negatively associated with MRSA colonization. More proper use of broad-spectrum antibiotics contributes to reducing MSSA colonization. Former smokers should also practice better personal hygiene to limit the possibility of MRSA colonization.

Profile of nasal and oropharyngeal colonization by Staphylococcus aureus in pharmacy students

É comum indivíduos saudáveis serem colonizados pelo Staphylococcus aureus, sendo o mesmo encontrado em diversas áreas do corpo, com maior frequência na cavidade nasal. Apesar de ser membro de microbiota, esse micro-organismo pode estar relacionado com uma variedade de doenças infecciosas. Em décadas anteriores as infecções por S. aureus eram tratadas com facilidade através do uso da penicilina e moléculas semissintéticas de β-lactâmicos, como a meticilina e seu análogo oxacilina. Entretanto, dentro de um curto período, à resistência à meticilina, foi detectada em cepas de S. aureus (MRSA – metthicillin-resistante Staphylococcus aureus), passando de um organismo presente predominantemente em hospitais para uma causa comum de infecções também dentro da comunidade. Considerando a importância das infecções nosocomiais e na comunidade, o presente trabalho teve como objetivo a avaliação do perfil de colonização nasal e oral pelo S. aureus, bem como a determinação da resistência à meticilina/oxacilina, entre os estudantes do curso de Farmácia. Também foi avaliado o perfil geral de contaminação dos aparelhos celulares (tipo smartphones), verificando a presença de S. aureus. Amostras da cavidade nasal, orofaringe e da superfície (tela frontal) do aparelho celular dos acadêmicos, foram coletadas utilizando-se swabs estéreis e semeadas em Agar Sal Manitol e Agar Mueller Hinton. A avaliação do perfil de sensibilidade das cepas de S. aureus isoladas dos estudantes foi realizada por técnica de difusão em agar. Dos 50 voluntários empregados na pesquisa, 29 (58%) apresentaram amostras positivas para o S. aureus na cavidade nasal e/ou oral. Sendo que, 14 voluntários (28%) possuíam o S. aureus somente na cavidade nasal, 5 (10%) somente na cavidade oral e 10 voluntários (20%) apresentaram a bactéria em ambos os locais (cavidade nasal e orofaringe). Dos portadores da bactéria, um voluntário (3,4%) apresentou cepa MRSA. Na contagem de micro-organismos mesófilos aeróbios totais (nos aparelhos celulares), 100% das amostras obtiveram crescimento, sendo que 80% apresentaram contagens menores ou iguais a 5 UFC/cm2 da superfície frontal do smartphone. Na pesquisa de bactérias específicas, 9 (18%) celulares revelaram a presença de S. aureus. Através dos resultados foi possível observar que a maioria dos estudantes apresentam S. aureus colonizando a cavidade nasal e/ou oral, entretanto, não sendo verificada uma alta porcentagem de cepas resistentes a oxacilina/meticilina. Todos os acadêmicos apresentaram aparelhos com algum nível de contaminação microbiológica, sendo detectado o S. aureus apenas nos aparelhos dos estudantes que eram portadores nasais e/ou orais dessa bactéria.

Bacterial Decolonization to Prevent Acute Radiation Dermatitis: A Randomized Controlled Trial

<h3>Purpose/Objective(s)</h3> Radiation dermatitis (RD) secondary to radiation therapy (RT) to treat cancer reduces quality of life (QoL) and can lead to treatment interruption. The exact etiology of RD is unknown, and bacteria play a role in other inflammatory dermatoses. As our group recently showed nasal colonization with <i>Staphylococcus aureus</i> (SA) prior to RT was an independent predictor of grade ≥2 RD, we conducted a randomized controlled trial evaluating efficacy of bacterial decolonization (BD) to prevent RD and improve QoL. <h3>Materials/Methods</h3> This is a randomized phase II trial comparing BD to standard of care (SC) for adult patients with breast cancer or head and neck cancer to receive fractionated (≥ 15 fractions) RT. Patients were randomized 1:1 to the BD intervention of intranasal mupirocin ointment twice daily and chlorhexidine body wash once daily for 5 consecutive days before RT start and repeated for 5 days every other week during RT or the SC arm of emollient use as needed. The primary endpoint was development of grade ≥2 RD using Criteria for Adverse Events v4.03, and the planned sample size was 80 patients. Evaluation of a preliminary cohort showed wide variability of disease in grade 2 RD, so grade 2 RD was further differentiated for more refined statistical analysis: "moderate to brisk erythema" defined as grade 2 and "patchy moist desquamation" defined as grade 2 with moist desquamation (2-MD). The secondary endpoint was patient-reported QoL assessed via the SKINDEX-16 (SD-16) questionnaire before and after RT. Bacterial culture swabs of the nares and skin at RT beginning, middle, and end were obtained for both groups. <h3>Results</h3> 80 patients were randomized 1:1 to each arm (40 BD, 40 SC) June 2019-August 2021. 78 breast and 2 head and neck cancer patients were enrolled instead of the projected 40 of each cancer type. 76 patients were included for analysis (38 BD, 38 SC). Clinical and demographic characteristics were well balanced between arms. We demonstrated prevention of RD grades 2-MD or higher in the BD arm compared to the SC arm (0/38, 0% vs 9/38, 23.68%; P=0.002). Additionally, BD resulted in a significantly lower median RD grade compared to SC (1.19±0.7 vs 1.58±0.75, P=0.019). Finally, a linear regression model showed a significant association between BD and decreased RD grade (estimate=-0.431, 95% CI: -0.7516, -0.1054; p=0.010), even when adjusting for other RD risk factors. Most patients reported no difficulty with BD and only one patient discontinued due to itch. There was no difference in QoL outcomes between arms. <h3>Conclusion</h3> Our results support the use of a bacterial decolonization regimen for preventing moist desquamation in patients receiving RT for breast or head and neck cancer. Our study included mainly breast cancer patients; thus, BD efficacy needs to be tested in other solid tumors receiving RT. This is the first study demonstrating efficacy of bacterial decolonization to reduce RD for cancer patients. Given the safety and availability of this regimen, we suggest adding BD to RD prophylaxis protocols.

Nasal Microbiome and Its Interaction with the Host in Childhood Asthma.

Childhood asthma is a major chronic non-communicable disease in infants and children, often triggered by respiratory tract infections. The nasal cavity is a reservoir for a broad variety of commensal microbes and potential pathogens associated with respiratory illnesses including asthma. A healthy nasal microenvironment has protective effects against respiratory tract infections. The first microbial colonisation in the nasal region is initiated immediately after birth. Subsequently, colonisation by nasal microbiota during infancy plays important roles in rapidly establishing immune homeostasis and the development and maturation of the immune system. Dysbiosis of microbiota residing in the mucosal surfaces, such as the nasopharynx and guts, triggers immune modulation, severe infection, and exacerbation events. Nasal microbiome dysbiosis is related to the onset of symptomatic infections. Dynamic interactions between viral infections and the nasal microbiota in early life affect the later development of respiratory infections. In this review, we summarise the existing findings related to nasal microbiota colonisation, dynamic variations, and host–microbiome interactions in childhood health and respiratory illness with a particular examination of asthma. We also discuss our current understanding of biases produced by environmental factors and technical concerns, the importance of standardised research methods, and microbiome modification for the prevention or treatment of childhood asthma. This review lays the groundwork for paying attention to an essential but less emphasized topic and improves the understanding of the overall composition, dynamic changes, and influence of the nasal microbiome associated with childhood asthma.

Does a Positive Methicillin-Resistant Staphylococcus aureus (MRSA) Nasal Screen Predict the Risk for MRSA Skin and Soft Tissue Infection?

Skin and soft tissue infections (SSTIs) are often caused by gram-positive bacteria that colonize the skin. Given the overuse of antibiotics, SSTIs are increasingly caused by resistant bacteria, including methicillin-resistant Staphylococcus aureus (MRSA). Guidance on the utility of MRSA nasal screening for MRSA SSTI is limited. To determine whether MRSA nasal screening predicts the risk of MRSA SSTIs. This was a single-center, retrospective cohort study of adult patients with an SSTI diagnosis that had MRSA nasal screening and wound cultures obtained within 48 hours of starting antibiotics. Sensitivity, specificity, positive and negative predictive value, and positive and negative likelihood ratios were calculated using VassarStats. Pretest and posttest probabilities were estimated with Microsoft Excel. A total of 884 patient encounters were reviewed between December 1, 2018, and October 31, 2021, and 300 patient encounters were included. The prevalence of MRSA SSTI was 18.3%. The MRSA nasal colonization had a sensitivity of 63.6%, specificity of 93.9%, positive predictive value of 70.0% (95% CI = 55.2%-81.7%), negative predictive value of 92.0% (95% CI = 87.7%-94.9%), positive likelihood ratio of 10.39 (95% CI = 6.12-17.65), negative likelihood ratio of 0.39 (95% CI = 0.27-0.55), positive posttest probability of 70.0%, and negative posttest probability of 8.0%. Given the high positive likelihood ratio, a positive MRSA nasal screen was associated with a large increase in the probability of MRSA SSTI at our institution, and a negative MRSA nasal screen was associated with a small but potentially significant decrease in the probability of MRSA SSTI.

Nasal colonization of methicillin-resistant Staphylococcus aureus in HIV-infected patients at the Cape Coast Teaching Hospital, Ghana

Methicillin-resistant Staphylococcus aureus (MRSA) continues to be associated with outbreaks in communities (CA-MRSA) and hospitals (HA-MRSA). MRSA isolates are known to be resistant to all beta-lactam antibiotics including methicillin. Moreover, HIV-infected individuals are highly at risk of CA-MRSA due to their weaker immune system. It is therefore important to keep surveillance of the prevalence. Our study aims at determining the prevalence of Staphylococcus aureus and MRSA among HIV-infected participants, the bacteria’s associations, and their antibiotic susceptibility patterns. A cross-sectional study was conducted and nasal swabs from 657 participants attending the HIV clinic at the Cape Coast Teaching Hospital were taken following guidelines. Confirmed S. aureus isolates were taken through antibiotic susceptibility tests per the Kirby–Bauer method, and isolates that were resistant to cefoxitin were considered to be MRSA. The carriage prevalence of S. aureus and MRSA was 44.7% and 8.2%, respectively, among the HIV-infected individuals. There was a significant association between hospitalization and MRSA colonization (p = 0.002), but not S. aureus colonization (p = 0.266). Significant association was also observed between age (p = 0.001), sex (p = 0.0001), and S. aureus colonization. Similarly, differences in age groups (p = 0.001), sex (p = 0.02), and MRSA colonization were statistically significant (p = 0.001). High percentage resistance was exhibited by the isolates to most of the antibiotics. However, this study did not record vancomycin resistance among the MRSA strains. The study showed high colonization of S. aureus and MRSA in HIV-infected patients, which was mostly associated with the age and sex of the individuals.

Corynebacterium accolens inhibits Staphylococcus aureus induced mucosal barrier disruption.

BackgroundCorynebacterium accolens (C. accolens) is a common nasal colonizer, whereas Staphylococcus aureus (S. aureus) is typically regarded a pathogenic organism in patients with chronic rhinosinusitis (CRS). This study aims to evaluate the interaction of the two bacteria in vitro.MethodsClinical isolates of C. accolens and S. aureus from sinonasal swabs, as well as primary human nasal epithelial cells (HNECs) cultured from cellular brushings of both healthy and CRS patients were used for this study. The cell-free culture supernatants of all isolates grown alone and in co-cultures were tested for their effects on transepithelial electrical resistance (TER), FITC-Dextran permeability, lactate dehydrogenase (LDH), and IL-6 and IL-8 secretion of HNECs. Confocal scanning laser microscopy and immunofluorescence were also used to visualize the apical junctional complexes. C. accolens cell-free culture supernatants were also tested for antimicrobial activity and growth on planktonic and biofilm S. aureus growth.ResultsThe cell-free culture supernatants of 3\\C. accolens strains (at 60% for S. aureus reference strain and 30% concentration for S. aureus clinical strains) inhibited the growth of both the planktonic S. aureus reference and clinical strains significantly. The C. accolens cell-free culture supernatants caused no change in the TER or FITC-Dextran permeability of the HNEC-ALI cultures, while the cell-free culture supernatants of S. aureus strains had a detrimental effect. Cell-free culture supernatants of C. accolens co-cultured with both the clinical and reference strains of S. aureus delayed the S. aureus-dependent mucosal barrier damage in a dose-dependent manner.ConclusionCorynebacterium accolens cell-free culture supernatants appear to inhibit the growth of the S. aureus planktonic bacteria, and may reduce the mucosal barrier damage caused by S. aureus.

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.

Pharmacist-Driven Methicillin-Resistant S. aureus Polymerase Chain Reaction Testing for Pneumonia.

Nasal colonization with methicillin-resistant Staphylococcus aureus (MRSA) can be detected using nasal swab polymerase chain reaction (PCR) assay and is associated with clinical MRSA infection. The MRSA nasal PCR has a rapid turnaround time and a negative predictive value for MRSA pneumonia of >98%; however, data are limited in critically ill patients. The purpose of this study is to determine the impact of a pharmacist-driven algorithm, utilizing MRSA PCR nasal screening on duration of anti-MRSA therapy in patients admitted to the intensive care unit (ICU) with suspected pneumonia. A single-center pre/post study was conducted in 4 ICUs at a large tertiary care community hospital. Adult patients admitted to the ICU initiated on vancomycin or linezolid for pneumonia managed using a pharmacist-driven MRSA PCR algorithm were included in the algorithm cohort. A historical cohort with standard management was matched 1:1 by age, type of pneumonia, and Acute Physiology and Chronic Health Evaluation II (APACHE II) score. The primary outcome was duration of anti-MRSA therapy. Secondary outcomes included MRSA rates, number of vancomycin levels, new onset of acute kidney injury (AKI), ICU length of stay (LOS), hospital LOS, and mortality. Of the 245 patients screened, 50 patients met inclusion criteria for the algorithm cohort and were matched to 50 patients in the historical cohort. The duration of anti-MRSA therapy was significantly lower compared with the historical cohort (47 vs 95 hours; P < 0.001). Secondary outcomes were similar between groups for MRSA rates, new onset of AKI, LOS, and mortality. There were less vancomycin levels ordered in the algorithm cohort (2 vs 3, P = 0.026). A pharmacist-driven MRSA PCR algorithm significantly reduced anti-MRSA duration of therapy in critically ill patients with pneumonia. Future studies should validate these results in critically ill populations and in settings where MRSA pneumonia is more prevalent.

Selection of Staphylococcus aureus in a murine nasopharyngeal colonization model.

Staphylococcus aureus nasal colonization is a risk factor for infection. A large proportion of the population are identified as potential S. aureus carriers yet we only partially understand the repertoire of genetic factors that promote long-term nasal colonization. Here we present a murine model of nasopharyngeal colonization that requires a low S. aureus inoculum and is amenable to experimental evolution approaches. We used this model to experimentally evolve S. aureus using successive passages in the nasopharynx to identify those genetic loci under selection. After 3 cycles of colonization, mutations were identified in mannitol, sorbitol, arginine, nitrite and lactate metabolism genes promoting key pathways in nasal colonization. Stress responses were identified as being under selective pressure, with mutations in DNA repair genes including dnaJ and recF and key stress response genes clpL, rpoB and ahpF. Peptidoglycan synthesis pathway genes also revealed mutations indicating potential selection for alteration of the cell surface. The murine model used here is versatile to question colonization, persistence and evolution studies.We studied the human pathogen Staphylococcus aureus in our search to determine factors that contribute to its ability to live in the human nose and throat. The anterior nares and nasopharynx are considered primary habitats but we do not understand how the pathogen adapts as it moves from one person to the next. We first determined sustained survival of the pathogen over multiple days in the nasopharynx that might act as a good model for human persistence due to the low numbers of bacteria needed for it to establish. By using successive rounds of colonization of the nasopharynx across different mice we revealed that multiple genetic changes in the S. aureus occurred. These changes were found in genes associated with the cell surface and metabolism and might indicate adaptation to the niche. One gene showed an accumulation of multiple mutations supporting a key contribution in adaptation but the role of the protein it encodes is not yet known. The contribution of these genes and genetic changes are unclear but indicate an area for future research to better understand how this common human pathogen is so successful at human colonization and survival.