Comparative evaluation of aggressiveness traits in staphylococcal strains from severe infections versus nasopharyngeal carriage

Kaempferol: Antimicrobial Properties, Sources, Clinical, and Traditional Applications

Flavonoids are a category of plant-derived compounds which exhibit a large number of health-related effects. One of the most well-known and studied flavonoids is kaempferol, which can be found in a wide variety of herbs and plant families. Apart from their anticarcinogenic and anti-inflammatory effects, kaempferol and its associated compounds also exhibit antibacterial, antifungal, and antiprotozoal activities. The development of drugs and treatment schemes based on these compounds is becoming increasingly important in the face of emerging resistance of numerous pathogens as well as complex molecular interactions between various drug therapies. In addition, many of the kaempferol-containing plants are used in traditional systems all over the world for centuries to treat numerous conditions. Due to its variety of sources and associated compounds, some molecular mechanisms of kaempferol antimicrobial activity are well known while others are still under analysis. This paper thoroughly documents the vegetal and food sources of kaempferol as well as the most recent and significant studies regarding its antimicrobial applications.

Retrospective study of the efficacy of vascularized tissue transfer for treating antibiotic-resistant bacteria-infected wound: Comparison with clean and antibiotic-sensitive bacteria-infected wound

If wounds are infected with bacteria resistant to an empirical antibiotic regimen, effective wound treatment will be delayed. This can delay wound healing and lengthen hospital stays, increasing the costs to patients. Long-term antibiotic use can also result in minor and major complications, such as diarrhea, antibiotic resistance, or life-threatening leukopenia. Multidrug-resistant (MDR) bacteria make wound treatment even more difficult. Traditionally, surgeons thought that adequate infection control should be established before soft tissue coverage. However, wounds infected by MDR do not heal well with this traditional method and there are no optimal treatment guidelines for MDR bacteria-contaminated wounds.We reviewed 203 patients who underwent vascularized flap surgery from 2012 to 2019 to cover wounds. Class IV and I wounds were compared according to the Centers for Disease Control and Prevention classification. Class IV was further classified as antibiotic-resistant (ARB) and antibiotic-sensitive (ASB) bacteria. Wound size, mode, location, pathogens, healing time, and basic demographics were evaluated. Data were compared using Cramer's V and one-way ANOVA or independent t tests.The average healing time was longer in the ARB (19.7 [range 7-44] days) and ASB (17.9 [range 2-36] days) groups than in the Clean group (16.5 [range 7-28] days). Healing time differed in the 3 groups (P = .036). It was longer in the class IV group than in the class I group (P = .01). However, it was not statistically different between the ARB and ASB groups (P = .164).In our study the difference in healing time was small when vascularized tissue transfer was done in ARB-infected wound compared with ASB-infected and clean wound. It is necessary to perform surgery using vascularized tissue for the infected wound of antibiotic-resistant bacteria.

Bacteriological Profile and Antimicrobial Susceptibility Patterns of Bloodstream Infection at Kigali University Teaching Hospital

BACKGROUND

Worldwide, bacterial bloodstream infections (BSIs) constitute an important cause of morbidity and mortality in clinical settings. Due to the limited laboratory facilities in sub-Saharan Africa, poor diagnosis of BSIs results in poor clinical outcomes and leads to a risk of antimicrobial resistance. The present work was carried out to describe the microbiological features of BSIs using the data collected from Centre Hospitalier Universitaire de Kigali (CHUK).

METHODS

A retrospective study was carried out at CHUK. The blood culture results of 2,910 cases - from adults, children and infants - were reviewed in the Microbiology service from October 2017 to October 2018. The following variables were considered: age, gender, admitting department, blood culture results, and antimicrobials sensitivity test results. Data were entered and analyzed using Microsoft Excel 2013.

RESULTS

Twelve percent (341/2,910) of blood culture results reviewed were positive with 108 (31.7%) Gram positive bacteria and 233 (68.3%) Gram negative bacteria. The most prevalent pathogens were Klebsiella pneumoniae 108 (31.7%) and Staphylococcus aureus 100 (29.3%). This study revealed a high resistance to commonly prescribed antibiotics such as penicillin, trimethoprim sulfamethoxazole, and Ampicillin with 91.8, 83.3, and 81.8% of resistance, respectively. However, bacteria were sensitive to imipenem and vancomycin with 98.1 and 94.3% of sensitivity, respectively. The pediatrics and neonatology departments showed a high number of positive culture with 97/341 (28.4%), and 93/341 (27%) respectively. The overall prevalence of multidrug resistance was 77.1%.

CONCLUSION

The prevalence of bacterial pathogens in BSIs was found to be high. The antibiotic resistance to the commonly used antibiotics was high. Appropriate treatment of BSIs should be based on the current knowledge of bacterial resistance pattern. This study will help in formulating management of diagnostic guidelines and antibiotic policy.

Staphylococcus aureus Nasal Colonization in Spanish Children. The COSACO Nationwide Surveillance Study

Objective

To assess the prevalence and risk factors for S. aureus and methicillin-resistant S. aureus (MRSA) nasal colonization in Spanish children.

Methods

Cross-sectional study of patients <14 years from primary care centers all over Spain. Clinical data and nasal aspirates were collected from March to July 2018.

Results

A total of 1876 patients were enrolled. Prevalence of S. aureus and MRSA colonization were 33% (95% CI 30.9–35.1) and 1.44% (95% CI 0.9–2), respectively. Thirty-three percent of the children (633/1876) presented chronic conditions, mainly atopic dermatitis, asthma and/or allergy (524/633). Factors associated with S. aureus colonization were age ≥5 years (OR 1.10, 95% CI 1.07–1.12), male sex (OR 1.43, 95% CI 1.17–1.76), urban setting (OR 1.46, 95% CI 1.08–1.97) and the presence of asthma, atopic dermatitis or allergies (OR 1.25; 95% CI: 1.093–1.43). Rural residence was the only factor associated with MRSA colonization (OR 3.62, 95% CI 1.57–8.36). MRSA was more frequently resistant than methicillin-susceptible S. aureus to ciprofloxacin [41.2% vs 2.6%; p<0.0001], clindamycin [26% vs 16.9%; p=0.39], and mupirocin [14.3% vs 6.7%; p=0.18]. None of the MRSA strains was resistant to tetracycline, fosfomycin, vancomycin or daptomycin.

Conclusions

The main risk factors for S. aureus colonization in Spanish children are being above five years of age, male gender, atopic dermatitis, asthma or allergy, and residence in urban areas. MRSA colonization is low, but higher than in other European countries and is associated with rural settings.

Methicillin-resistant Staphylococcus aureus colonization in patients undergoing primary total hip arthroplasty

Introduction. Nasal and skin colonization by methicillin-resistant Staphylococcus aureus (MRSA) are linked to a higher incidence of infection after total joint replacement. The prevalence of colonization is poorly defined in Latin American countries.Aim. The aim of the present study was to determine the prevalence of MRSA colonization in the nostrils and groin using real-time polymerase chain reaction (RT-PCR) in patients undergoing total hip arthroplasty (THA).Methodology. In this cross-sectional study, 146 patients undergoing THA between December 2015 and March 2017 in a tertiary-care university-affiliated hospital in Chile were screened for MRSA colonization before the procedure using RT-PCR independently in the nostrils and groin. Risk factors for colonization were documented.Results. Seven of the 146 (5 %) patients undergoing THA were carriers of MRSA in the nostrils and/or the groin. Recent antibiotic use was identified as a risk factor for colonization, OR=4.86 [95 % confidence interval (CI): 1.56-13.96]. Patients reporting at least one of the seven surveyed risk factors had an OR of 2.39 (95 % CI: 0.37-25.77) for colonization. MRSA colonization frequency was twofold higher in the groin as opposed to the nostrils (P=0.014).Conclusion. Five percent of the patients undergoing THA were identified as carriers of MRSA. Recent antibiotic use is a relevant risk factor for MRSA colonization in patients undergoing primary total hip arthroplasty.

Risk Factors And Clinical Outcomes Of Hospital-Acquired MRSA Infections In Chongqing, China

Background

Methicillin-resistant Staphylococcus aureus (MRSA) is a common pathogen of hospital infection with multi-drug resistant characteristics. Its spread and epidemic pose great challenges to nosocomial infection control. This study was aimed to identify risk factors for hospital-acquired MRSA (HA-MRSA) infections and investigate its clinical outcome, developing infection control strategies and improving patient outcomes.

Methods

A retrospective case-case-control study was conducted to compare patients in Southwest Hospital, Chongqing, People's Republic of China from January 2018 to December 2018 with control patients. In this study, 251 patients with MRSA nosocomial infection, 339 patients with methicillin-sensitive Staphylococcus aureus strains (MSSA) nosocomial infection, and 300 patients with non-Staphylococcus aureus infection were included.

Results

Multivariate analysis showed that presence of central venous catheters (odds ratio [OR], 1.932; 95% confidence interval [CI], 1.074–3.477; P=0.028), sputum suction (OR, 2.887; 95% CI, 1.591–5.240; p<0.001), and total hospital stays more than 30 days (OR, 3.067; 95% CI, 2.063–4.559; P<0.001) were independent risk factors for HA-MRSA. Renal insufficiency (OR, 2.744; 95% CI, 1.089–6.914; P=0.032) and receipt of immunosuppressors (OR, 3.140; 95% CI, 1.284–7.678; P=0.012) were independent predictors of poor prognosis of MRSA nosocomial infection. Moreover, empirical use of antibiotics (OR, 0.514; 95% CI, 0.282–0.935; P=0.029) was a protective factor for poor prognosis of MRSA nosocomial infection. In-hospital mortality in the MRSA group was not statistically significant compared with the other two groups; however, the rate of poor prognosis in the MRSA group was higher than that of the MSSA group (27.5% vs 17.1%, χ²=9.200, P=0.002) and the control group (27.5% vs 16.0%, χ²=19.190, P=0.001).

Conclusion

Our results have shown presence of central venous catheters, sputum suction, and total hospital stays more than 30 days were associated with nosocomial MRSA infection. Patients with renal insufficiency and immunosuppressive therapy were more likely to cause poor prognosis with MRSA infection, and the empirical use of antibiotics can effectively reduce the adverse clinical outcomes caused by MRSA infection. Based on above findings, strategies to control MRSA infection should emphasize more attention to these patients and appropriate empirical use of antibiotics.

Communication is the key: biofilms, quorum sensing, formation and prevention

Antibiotic resistance is a relevant topic nowadays, representing one of the main causes of infection-related mortality and morbidity at a global level. This phenomenon is worrisome and represents an area of interest for both clinical practice and fundamental research. One important mechanism whereby bacteria acquire resistance to antibiotics and evade the immune system is by forming biofilms. It is estimated that ~80% of the bacteria producing chronic infections can form biofilms. During the process of biofilm formation microorganisms have the ability to communicate with each other through quorum sensing. Quorum sensing regulates the metabolic activity of planktonic cells, and it can induce microbial biofilm formation and increased virulence. In this review we describe the biofilm formation process, quorum sensing, quorum quenching, several key infectious bacteria producing biofilm, methods of prevention and their challenges and limitations. Although progress has been made in the prevention and treatment of biofilm-driven infections, new strategies are required and have to be further developed.

Clinical S. aureus Isolates Vary in Their Virulence to Promote Adaptation to the Host

Staphylococcus aureus colonizes epithelial surfaces, but it can also cause severe infections. The aim of this work was to investigate whether bacterial virulence correlates with defined types of tissue infections. For this, we collected 10–12 clinical S. aureus strains each from nasal colonization, and from patients with endoprosthesis infection, hematogenous osteomyelitis, and sepsis. All strains were characterized by genotypic analysis, and by the expression of virulence factors. The host–pathogen interaction was studied through several functional assays in osteoblast cultures. Additionally, selected strains were tested in a murine sepsis/osteomyelitis model. We did not find characteristic bacterial features for the defined infection types; rather, a wide range in all strain collections regarding cytotoxicity and invasiveness was observed. Interestingly, all strains were able to persist and to form small colony variants (SCVs). However, the low-cytotoxicity strains survived in higher numbers, and were less efficiently cleared by the host than the highly cytotoxic strains. In summary, our results indicate that not only destructive, but also low-cytotoxicity strains are able to induce infections. The low-cytotoxicity strains can successfully survive, and are less efficiently cleared from the host than the highly cytotoxic strains, which represent a source for chronic infections. The understanding of this interplay/evolution between the host and the pathogen during infection, with specific attention towards low-cytotoxicity isolates, will help to optimize treatment strategies for invasive and therapy-refractory infection courses.

The significance of bacterial engulfment in Gram-stained sputum in patients with respiratory infections

In general, physicians believe that the presence of bacterial engulfment in white blood cells (WBCs) on Gram-stained sputum is a hallmark of lower respiratory infection. However, no studies have described the significance or diagnostic accuracy of engulfment in lower respiratory tract infections.We prospectively studied sputum samples by Gram staining (Favor method) for their quality and engulfment score in WBCs obtained from patients with respiratory symptoms at inpatient and outpatient settings at Kyorin University Hospital between December 2012 and April 2015.A total of 163 patients were enrolled. The patients were classified into an infection (n = 93) or non-infection (n = 70) group based on clinical or radiological findings prior to the evaluation of sputum samples. The proportion of engulfment-positive cases was equal in the infection and non-infection groups (49.5% vs 35.7%, P = 0.11). In the infection group, the engulfment score (%) for Streptococcus pneumoniae was significantly lower (median 3%, interquartile range [IQR]: 2% to 5%, P = 0.005) than that of the non-S. pneumoniae bacteria (H. influenzae, M. catarrhalis, and methicillin-susceptible Staphylococcus aureus (MSSA))(median 22.5%, IQR: 17% to 35.5%). The engulfment score of S. pneumoniae in the WBC was low in the infection group, and no cases were recognized in the non-infection group. Using a cut-off value of 3%, the diagnostic accuracy for infection was as follows: sensitivity: 50%, specificity: 65.7%, and area under the curve (AUC): 0.579 (95% CI 0.464 to 0.694). For the non-S. pneumoniae bacteria (H. influenzae, M. catarrhalis, and MSSA), the engulfment score was significantly higher in the infection group (median 22.5%, IQR 17 to 35.5%) than in the non-infection group (median 6.0%, IQR: 3 to 13%, P = 0.011), and the diagnostic accuracy for infection was as follows: sensitivity: 75%, specificity: 85.7%, and AUC: 0.902 (95% CI 0.75 to 1.00) when the threshold for the engulfment score was defined as 18%.This study provides the first evidence that the engulfment of bacteria in WBCs is not always indicative of infection and that the engulfment score can fluctuate according to the pathogen.