Marina Macedo-Viñas

(1) Background: Infections are a main cause of morbidity and mortality among burn patients. The spectrum of microorganisms depends on the epidemiological context and treatment practices. We aimed to describe the evolution of microbial flora colonizing burn wounds among patients hospitalized during 15 or more days at the National Burn Center in 2015. (2) Methods: Demographic data, length of stay, total body surface area burn, and status at discharge were collected from electronic records and culture results from the laboratory database. (3) Results: Among 98 included patients, 87 were colonized. The mean length of stay was 39 days overall and 16 days in the ICU. Acinetobacter spp., Enterococcus spp., and Staphylococcus aureus predominated. Fifty-six patients harbored multidrug-resistant bacteria and had a significantly greater TBSA. The mean time to colonization was 6 days overall and 14 days for multidrug-resistant bacteria; it was significantly longer for methicillin-resistant S. aureus than for methicillin-susceptible S. aureus. (4) Conclusions: This is the first report describing the dynamics of microbial colonization of burn wounds in Uruguay. Similarities were found with reports elsewhere, but early colonization with yeasts and the absence of Streptococcus pyogenes were unique. Each burn center needs to monitor its microbial ecology to tailor their antimicrobial strategies effectively.

Background: Pseudomonas aeruginosa is the main pathogen responsible for lung destruction in cystic fibrosis, becoming difficult to eradicate in chronic infection. Aims: To describe antibiotic resistance among strains of P.aeruginosa isolated from sputa of patients with cystic fibrosis. To investigate in vivo and in vitro expression of genes related to antibiotic resistance and anaerobic growth. Methods: Sputa (in vivo) and strains (in vitro) from 26 patients were obtained during 17 months. Genotypes were compared by random polymorphic DNA amplification. Expression of nirS (anaerobic respiration) and mexY (MexXY efflux pump) were measured by quantitative real time polymerase chain reaction. Expression levels of nirS in aerobiosis and anaerobiosis were compared to estimate oxygenation status within lungs. Mutations in the regulator gene mexZ were investigated in sputa expressing mexY and were correlated with strains’ antibiotic resistance. Results: Nine patients and 56 sputa were finally analysed. Seven patients carried a single genotype. Gene mexY was detected in all the sputa; expression levels were higher in sputa with mexZ mutations. Multi-resistance was frequent. Resistance profiles not always correlated with mexY expression levels or mexZ mutations. Comparison of in vivo and in vitro nirS expression indicated mainly aerobic and microaerophilic environments within sputa. Discussion: Mutations in e mexZ are frequent in strains of P.aeruginosa colonising patients with cystic fibrosis. Presence of these mutations correlates with increased expression of mexY in vivo and in vitro, but no with in vivo antibiotic resistance. Results of nirS expression suggest that the lungs represent heterogeneous environments regarding oxygenation status. This complexity explains that mechanisms of growth and antibiotic resistance within the lungs of these patients are still largely unknown. Conclusions: After many years of research few studies, including the present, revealed different aspects of in vivo growth of P. aeruginosa. We determined a cut-off to discriminate between sputa containing mexZ wild type and mutated alleles and showed that comparison of in vivo and in vitro nirS expression allows to predict oxygenation status. So far, none of the studies can explain all the factors influencing the behaviour of P.aeruginosa colonising cystic fibrosis patients making it difficult to design new therapeutic strategies.

We aimed to estimate for the first time the burden of fungal infections in Uruguay. Data on population characteristics and underlying conditions were extracted from the National Statistics Institute, the World Bank, national registries, and published articles. When no data existed, risk populations were used to estimate frequencies extrapolating from the literature. Population structure (inhabitants): total 3,444,006; 73% adults; 35% women younger than 50 years. Size of populations at risk (total cases per year): HIV infected 12,000; acute myeloid leukemia 126; hematopoietic stem cell transplantation 30; solid organ transplants 134; COPD 272,006; asthma in adults 223,431; cystic fibrosis in adults 48; tuberculosis 613; lung cancer 1400. Annual incidence estimations per 100,000: invasive aspergillosis, 22.4; candidemia, 16.4; Candida peritonitis, 3.7; Pneumocystis jirovecii pneumonia, 1.62; cryptococcosis, 0.75; severe asthma with fungal sensitization, 217; allergic bronchopulmonary aspergillosis, 165; recurrent Candida vaginitis, 6323; oral candidiasis, 74.5; and esophageal candidiasis, 25.7. Although some under and overestimations could have been made, we expect that at least 127,525 people suffer from serious fungal infections each year. Sporothrichosis, histoplasmosis, paracoccidioidomycosis, and dermatophytosis are known to be frequent but no data are available to make accurate estimations. Given the magnitude of the burden of fungal infections in Uruguay, efforts should be made to improve surveillance, strengthen laboratory diagnosis, and warrant access to first line antifungals.

Gardnerella vaginalis is infrequently reported as a cause of extragenital infections. Although the pathogenesis of G. vaginalis is not completely understood, available clinical data suggest that it is an opportunistic pathogen that can cause invasive infections. We report a case of pyelonephritis imputed to G. vaginalis, with renal abscess and bacteremia in a diabetic nonpregnant woman with polycystic kidney disease. Gardnerella vaginalis was isolated from blood, the abscess, and urine obtained by direct placement of a pigtail into the kidney. Identification was made with molecular methods. We present a review of the literature concerning G. vaginalis extragenital infections, with special focus on abscesses and bacteremias. We searched PubMed for articles in English, French, German, and Spanish languages. Only 15 cases of abscesses from diverse body sites have been reported. We found 28 articles describing a total of 117 cases of bacteremia. Most of them occurred in women in the peripartum periods and in newborns. Cases in men have been described with lower frequency. The importance of this agent might be underestimated because microbiological diagnosis is difficult. Most cases in adults were nonfatal and without sequelae. There is no consensus on the antibiotic regimen and duration of treatment for these infections. New microbiological diagnosis tools may lead to prompt identification of this microorganism and help to elucidate its participation in localized and systemic infections.

Objectives The therapeutic arsenal for MRSA infections is limited. The aim of this study was to assess the non-inferiority of a combination of trimethoprim/sulfamethoxazole plus rifampicin versus linezolid alone for the treatment of MRSA infection. Methods We conducted a randomized, open-label, single-centre, non-inferiority trial comparing trimethoprim/sulfamethoxazole (160 mg/800 mg three times daily) plus rifampicin (600 mg once a day) versus linezolid (600 mg twice a day) alone in adult patients with various types of MRSA infection. Patients were allocated 1: 1 to either regimen. The primary outcome was clinical cure at 6 weeks after the end of treatment (non-inferiority margin 20%) assessed by both ITT and PP analyses. Secondary outcomes included the microbiologically documented persistence of MRSA in clinical cultures, mortality and adverse events. The study protocol has been registered with ClinicalTrials.gov (NCT00711854). Results Overall, 150 patients were randomized to one of the two treatment arms between January 2009 and December 2013 and were included in the ITT analysis. Of these 56/75 (74.7%) in the linezolid group and 59/75 (78.7%) in the trimethoprim/sulfamethoxazole and rifampicin group experienced clinical success (risk difference 4%, 95% CI −9.7% to 17.6%). The results were confirmed by the PP analysis, with 54/66 (81.8%) cured patients in the linezolid group versus 52/59 (88.1%) in the trimethoprim/sulfamethoxazole and rifampicin group (risk difference 6.3%, 95% CI −6.8% to 19.2%). There were no statistically significant differences between the two groups in any of the secondary outcomes, including microbiologically documented failure. Four adverse drug reactions attributed to the study medication occurred in the linezolid group versus nine in the trimethoprim/sulfamethoxazole and rifampicin group. Conclusions Compared with linezolid, trimethoprim/sulfamethoxazole and rifampicin seems to be non-inferior in the treatment of MRSA infection.

Introduction: Staphylococcus aureus produces a variety of diseases among children, ranging from skin and soft tissue infections to invasive life-threatening diseases. Since 1990, an increasing number of diseases produced by community-associated methicillin-resistant S. aureus (CA-MRSA) isolates have been reported. The aim of this study was to describe the importance and the microbiological characteristics of S. aureus isolates recovered from children treated at the Hospital Pediátrico del Centro Hospitalario “Pereira Rossell” (HP-CHPR); focusing on invasive diseases caused by CA-MRSA isolates, as well as some clinical aspects of the diseases they have produced. Methodology: One hundred and twenty-five S. aureus isolates recovered from the HP-CHPR between 2003 and 2006 from children with invasive (n=89) and superficial diseases (n=36) were included. Genotypic and phenotypic characteristics of S. aureus isolates and relevant clinical aspects of each child were studied. Results: CA-MRSA isolates accounted for 73% of all S. aureus recovered from invasive (mainly bone and joint) infections, pneumonia and bacteraemia. The most common CA-MRSA strain recovered from invasive (n=65) and superficial (n=36) diseases had the following features: pulsotype A (type USA1100), SCCmec cassette type IV, Panton-Valentine Leukocidin genes positive, susceptibility to trimethoprim-sulfamethoxazole without the inducible macrolide-lincosamide-streptogramin B (iMLS_B) resistance phenotype. No association between genotypic characteristics of invasive CA-MRSA isolates and clinical outcomes was found. Conclusions: CA-MRSA isolates produced a wide spectrum of invasive diseases in a public paediatric hospital between 2003 and 2006. Microbiologic characterization suggests the spread of an adapted CA-MRSA clone lacking erm genes.