Inside-out, antimicrobial resistance mediated by efflux pumps in clinical strains of Acinetobacter baumannii isolated from burn wound infections.

Acinetobacter baumannii belongs to the ESKAPE group. It is classified as a critical priority group by the World Health Organization and a global concern on account of its capacity to acquire and develop resistance mechanisms to multiple antibiotics. Data from the United States indicates 500 deaths annually. Resistance mechanisms of this bacterium include enzymatic pathways such as ß-lactamases, carbapenemases, and aminoglycoside-modifying enzymes, decreased permeability, and overexpression of efflux pumps. A. baumannii has been demonstrated to possess efflux pumps, which are classified as members of the MATE family, RND and MFS superfamilies, and SMR transporters. The aim of our work was to assess the distribution of efflux pumps and their regulatory gene expression in clinical strains of A. baumannii isolated from burned patients. METHODS: From the Clinical Microbiology Laboratory at the Instituto Nacional de Rehabilitación Luis Guillermo Ibarra Ibarra collection in Mexico, 199 strains were selected. Antibiotics susceptibilities were performed by broth microdilutions to determine minimal inhibitory concentrations. Phenotypic assays with efflux pump inhibitors were conducted using carbonyl cyanide 3-chlorophenylhydrazone (CCCP) and phenylalanine-arginine ß-naphthylamide (PAßN) in conjunction with amikacin, ceftazidime, imipenem, meropenem and levofloxacin. A search was conducted for structural genes that are linked to efflux pumps, and the relative expression of the adeR, adeS, and adeL genes was analyzed. RESULTS: Among a total of 199 strains, 186 exhibited multidrug resistance (MDR). Fluoroquinolones demonstrated the highest resistance rates, while minocycline and amikacin displayed comparatively reduced resistance rates (1.5 and 28.1, respectively). The efflux activity of fluorquinolones exhibited the highest phenotypic detection (from 85 to 100%), while IMP demonstrated the lowest activity of 27% with PAßN and 43.3% with CCCP. Overexpression was observed in adeS and adeL, with adeR exhibiting overexpression. Concluding that clinical strains of A. baumannii from our institution exhibited efflux pumps as one of the resistance mechanisms.

Evaluation of Burn Wound Infection in a Referral Center in Colombia.

Introduction Burn wound infection (BWI) is the second most important cause of death in burn patients. There is currently limited data about the incidence and clinical presentation of BWI using quantitative techniques as quantitative biopsy culture (QBC) to prevent progress to burn wound sepsis (BWS). Methods This is a prospective cohort study of patients diagnosed with BWI, confirmed by QBC, from February 2018 to July 2019 at University Hospital of Santander (HUS). The primary outcome was to determine clinical, microbiological, and histopathological characteristics of patients diagnosed with BWI along with a positive QBC and their relationship with early diagnosis and progression to BWS. Results 525 patients were admitted to HUS Burn Center. Of those, 44/525 (8.23%) presented a clinical diagnosis of BWI (median age, 20.5 years [1-67 years]; 25/44 [56.8%] male). QBC was positive in 26/44 (59%), Staphylococcus aureus 14/44 (31.8%), and Pseudomonas aeruginosa 7/44 (15.9%) were the mainly etiological agents isolated. Bacterial resistance to antibiotics was mostly to beta-lactams in 14/44 (31.8%), corresponding to methicillin-resistant Staphylococcus aureus (MRSA). Clinical signs more related to infection were erythema in 33/44 (61.3%). As many as 10/44 (22.7%) progressed to sepsis and 2/44 (6%) died. Conclusion BWI increases hospitalization time and number of surgeries, increasing the risk of sepsis and death. The QBC allows an accurate diagnosis with lesser false-positive cases that impact antibiotic resistance and mortality. Protocols targeting this problem are needed to decrease the impact of this.

Healthcare-associated infections in burn patients: Timeline and risk factors.

BACKGROUND: Healthcare-associated infections (HAIs) remain a major challenge in burn research and care. We aimed to describe the epidemiology and timeline of HAIs and to estimate the association of demographics and clinical characteristics with time to HAI among burn patients. METHODS: A prospective cohort study was conducted in a referral burn unit in southwestern Colombia. Incidence rates were calculated for HAI types and microorganisms, using a Poisson regression model. Univariable and multivariable Cox proportional hazards regression was used to estimate the effect of risk factors on time to first HAI. RESULTS: Of 165 burn patients, 46 (27.9%) developed at least one HAI (incidence rate of 21.8 per 1000 patient-days). The most frequent HAIs were burn wound infections, followed by bloodstream infections. The most common microorganisms were Staphylococcus aureus, Pseudomonas spp., and Acinetobacter baumannii. Whereas gram-negative bacteria were the most common microorganisms causing HAIs, gram-positive bacteria were the first microorganisms isolated after hospital admission. The independent risk factors associated with time to first HAI were burn size (TBSA>20%), burn mechanism (flames and scalds), central venous catheter use, and mestizo race. CONCLUSION: These data have implications toward generating empirical antibiotic guidelines and preventive strategies targeting the patients at highest risk for HAI.

Infection in burn patients in a referral center in Colombia.

INTRODUCTION: Worldwide, burns are responsible for more than 300,000 deaths annually; infection is a major cause of morbidity and mortality in these patients. Early identification and treatment of infection improves outcome. Toward this end it's necessary to identify the institutions flora and organisms that most frequently produces infection. OBJECTIVES: To characterize infections developed by burn patients hospitalized at the University Hospital of Santander (HUS). METHODOLOGY: Burn patients hospitalized in the HUS from January 1 to December 2014 were followed. Medical information regarding infections, laboratory and pathology reports were obtained. Statistical analysis with measures of central tendency, proportions, global and specific incidence density plus overall and specific incidence was obtained. For the microbiological profile proportions were established. RESULTS: 402 burn patients were included, 234 (58.2%) men and 168 (41.8%) women, aged between 6 days and 83 years, median 12.5 years. The burn agents include scald (52.5%), fire (10.0%), gasoline (9.2%), electricity (7.5%), among others. Burn area ranged from 1% to 80% TBS. Cumulative mortality was 1.5%. 27.8% of burned patients had one or more infections. Identified infections include folliculitis (27.0%), urinary tract infection (19.0%), infection of the burn wound (10.4%), pneumonia (8.6%), Central venous catheter (7.4%), bloodstream infection (7.4%) and skin grafts infection (4.3%) among others. Bacteria were responsible for 88.5% of the cases and fungi 11.5%. The most frequently isolated germs were P. aeruginosa, A. baumannii, E. coli, S. aureus and K. pneumoniae. Most gram-negative bacteria were sensitive to Amikacin, gram positive bacteria were sensitive to multiple antibiotics. CONCLUSION: Burns is a severe trauma that occurs in adult and pediatric patients, has several causative agents and can compromise the patient's life. The burned patient is at risk for a variety of infections. According to the type of infection it is possible to infer the most common causative organisms and their antibiotic sensitivity/resistance which allow a directed early empiric treatment.