Acquired blaVIM and blaGES Carbapenemase-Encoding Genes in Pseudomonas aeruginosa: A Seven-Year Survey Highlighting an Increasing Epidemiological Threat.

(1) Background: Pseudomonas aeruginosa is a Gram-negative bacterium with several intrinsic and acquired antimicrobial resistance mechanisms. The spread of carbapenemase-encoding genes, an acquired mechanism, enables carbapenem resistance in clinical settings. Detection of the carbapenemase-producer strains is urgent. Therefore, we aimed to characterize carbapenemase production in the clinical strains of P. aeruginosa at a tertiary-care center. (2) Methods: We included clinical strains of P. aeruginosa (from August 2011 to December 2018) with resistance towards at least one carbapenem. Strains were isolated in a tertiary-care center in Mexico City. Antimicrobial susceptibility profiles were determined by broth microdilution. Screening for carbapenemase-encoding genes was performed in all strains. Phenotypic assays (CarbaNP and mCIM) were conducted. Additional modifications to mCIM were also tested. (3) Results: One-hundred seventy-one P. aeruginosa strains out of 192 included in this study were resistant towards at least one of the carbapenems tested. Forty-seven of these strains harbored a carbapenemase-encoding gene. VIM (59.6%) and GES (23.4%) were the most frequently found carbapenemases in our study, followed by IMP (14.9%). (4) Among the most frequent carbapenemase genes identified, metallo-ß-lactamases were the most prevalent, which impair new treatment options. Searching for carbapenemase genes should be performed in resistant isolates to stop transmission and guide antimicrobial treatment.

Comparison of Lateral Flow Immunochromatography and Phenotypic Assays to PCR for the Detection of Carbapenemase-Producing Gram-Negative Bacteria, a Multicenter Experience in Mexico.

The identification of carbapenemase-producing Enterobacterales and Pseudomonas aeruginosa is important for treating and controlling hospital infections. The recommended methods for their identification require a long waiting time, technical training, and expertise. Lateral flow immunoassays such as NG-Test CARBA 5® overcome these needs. We analyzed 84 clinical isolates of carbapenem-resistant Enterobacterales and P. aeruginosa from four different hospitals in a two-year period. Antimicrobial resistance patterns were confirmed with the broth dilution method. Evaluation of KPC, VIM, NDM, IMP, and OXA-48-like enzymes was performed and compared to NG-Test CARBA 5 and phenotypic assays. Enterobacterales represented 69% of isolates and P. aeruginosa represented 31%. Carbapenemase-producing strains were 51 (88%) of Enterobacterales and 23 (88.4%) of P. aeruginosa; 20 (34%) and 23 (88%) were Class B ß-lactamases, respectively. The NG-Test CARBA 5® assay for Enterobacterales showed high sensitivity (98%), specificity (100%), and PPV (100%); however, it did not for P. aeruginosa. The Kappa concordance coefficient was 0.92 for Enterobacterales and 0.52 for P. aeruginosa. NG-Test CARBA 5® is a fast and easy-to-use assay. In Enterobacterales, we found excellent agreement in our comparison with molecular tests. Despite the low agreement in P. aeruginosa, we suggest that this test could be used as a complementary tool.

Serological prevalence of SARS-CoV-2 infection and associated factors in healthcare workers in a "non-COVID" hospital in Mexico City.

BACKGROUND: Mexico is one of the countries with the highest number of deaths from the COVID-19 pandemic. In spite of this high mortality, in Mexico the number of confirmed cases and diagnostic tests per million population are lower than for other comparable countries, which leads to uncertainty about the actual extent of the pandemic. In Mexico City, healthcare workers represent an important fraction of individuals with SARS-CoV-2 infection. We performed a cross-sectional study whose objective was to estimate the frequency of antibodies to SARS-CoV-2 and identify associated factors in healthcare workers at a large hospital in Mexico City. METHODS: We conducted a serological survey in a non-COVID national referral teaching hospital. The study population included all the personnel that works, in any capacity, in the hospital. From this population we selected a representative sample of 300 individuals. Blood samples were collected and questionnaires were applied between August 10th and September 9th, 2020. RESULTS: ELISA results indicate a serological prevalence of SARS-CoV-2 infection of 13.0%. Working in the janitorial and security groups, having an educational level below a university degree, and living with a larger number of people, were all identified as sociodemographic factors that increase the probability of having SARS-CoV-2 infection. CONCLUSIONS: Less favored socioeconomic groups face significantly higher prospects of experiencing SARS-CoV-2 infection and in institutions such as ours, providing janitorial and security workgroups with additional testing and counseling could help to limit the spread of contagion. The rate from the official number of confirmed cases in Mexico City is substantially smaller than the seropositive rate identified in this work.

Drug resistance phenotypes and genotypes in Mexico in representative gram-negative species: Results from the infivar network.

AIM: This report presents phenotypic and genetic data on the prevalence and characteristics of extended-spectrum ß-lactamases (ESBLs) and representative carbapenemases-producing Gram-negative species in Mexico. MATERIAL AND METHODS: A total of 52 centers participated, 43 hospital-based laboratories and 9 external laboratories. The distribution of antimicrobial resistance data for Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae complex, Acinetobacter baumannii complex, and Pseudomonas aeruginosa in selected clinical specimens from January 1 to March 31, 2020 was analyzed using the WHONET 5.6 platform. The following clinical isolates recovered from selected specimens were included: carbapenem-resistant Enterobacteriaceae, ESBL or carbapenem-resistant E. coli, and K. pneumoniae, carbapenem-resistant A. baumannii complex, and P. aeruginosa. Strains were genotyped to detect ESBL and/or carbapenemase-encoding genes. RESULTS: Among blood isolates, A. baumannii complex showed more than 68% resistance for all antibiotics tested, and among Enterobacteria, E. cloacae complex showed higher resistance to carbapenems. A. baumannii complex showed a higher resistance pattern for respiratory specimens, with only amikacin having a resistance lower than 70%. Among K. pneumoniae isolates, blaTEM, blaSHV, and blaCTX were detected in 68.79%, 72.3%, and 91.9% of isolates, respectively. Among E. coli isolates, blaTEM, blaSHV, and blaCTX were detected in 20.8%, 4.53%, and 85.7% isolates, respectively. For both species, the most frequent genotype was blaCTX-M-15. Among Enterobacteriaceae, the most frequently detected carbapenemase-encoding gene was blaNDM-1 (81.5%), followed by blaOXA-232 (14.8%) and blaoxa-181(7.4%), in A. baumannii was blaOXA-24 (76%) and in P. aeruginosa, was blaIMP (25.3%), followed by blaGES and blaVIM (13.1% each). CONCLUSION: Our study reports that NDM-1 is the most frequent carbapenemase-encoding gene in Mexico in Enterobacteriaceae with the circulation of the oxacillinase genes 181 and 232. KPC, in contrast to other countries in Latin America and the USA, is a rare occurrence. Additionally, a high circulation of ESBL blaCTX-M-15 exists in both E. coli and K. pneumoniae.

Association of TLR4 gene polymorphisms with sepsis after a burn injury: findings of the functional role of rs2737190 SNP.

Sepsis is a life-threatening organ dysfunction condition caused by a dysregulated response to an infection that is common among patients with moderate to severe burn injury. Previously, genomic variants in Toll-like receptor 4 (TLR4), a key innate immunity receptor, have been associated with sepsis and infection susceptibility. In this study, the association of six TLR4 SNPs with sepsis after burn injury was tested in the Mexican mestizo population. We found that the rs2737190 polymorphism is associated with sepsis after burn trauma. Interestingly, the G allele and GG genotype were associated with a lower risk of developing sepsis. Since the rs2737190 SNP is in the promoter region of the TLR4 gene, we analyzed the possibility that this polymorphism regulates the TLR4 pathway. We cultured peripheral blood mononuclear cells from different genotype carriers and found, after stimulation with LPS, that carriers of the GG genotype showed a higher expression of TLR4, IL6, and TNFα than AA genotype carriers. The results suggest that the GG genotype produces an increase in the TLR4 expression, and therefore an improvement in the immune response. We conclude that the rs2737190 polymorphism may become a useful marker for genetic studies of sepsis in patients after a burn injury.

Escherichia fergusonii in a patient with a traumatic amputation of the right pelvic limb.

El nombre de Escherichia fergusonii es en honor del microbiólogo William H. Ferguson. Es un bacilo gramnegativo, móvil, oxidasa negativo, catalasa positivo, reductor de nitrato y fermentador, oportunista que se asocia a infecciones de sitio quirúrgico. Una niña de 12 años fue remitida a un servicio de urgencias ortopédicas en la Ciudad de México con amputación traumática de la extremidad pélvica derecha. Tenía exposición ósea y requirió varios desbridamientos quirúrgicos. En el hueso y el tejido muscular se aisló E. fergusonii solo resistente a trimetoprima-sulfametoxazol y ampicilina, más otros gérmenes. Recibió un mes de ertapenem más ampicilina, con marcada mejoría.The name of Escherichia fergusonii was in honor of the microbiologist William H. Ferguson. It is a gram-negative rod, motile, oxidase negative,catalase positive, nitrate reducing and fermenter. Opportunistic that is associated with surgical site infections. A 12-year-old girl was referred to an orthopedic emergency department in Mexico City with a traumatic amputation of the right leg, she had bone exposure and required several surgical debridements. From bone and soft tissue samples we isolated E. fergusonii only resistant to trimethoprim sulfamethoxazole and ampicillin, and other germs. She received a month of ertapenem plus ampicillin with marked improvement.

Leuconostoc mesenteroides periprosthetic knee infection, an unusual fastidious Gram-positive bacteria: a case report.

BACKGROUND: Periprosthetic joint infections are mainly caused by Gram-positive cocci. Leuconostoc mesenteroides is a rare microorganism mainly causing bloodstream infections. At times, it might be confused with another type of cocci and give rise to misdiagnosed infections. Molecular diagnosis and biofilm production comprise important techniques to guide antibiotic treatment. CASE PRESENTATION: A 68-year-old Hispanic female with a previous history of bilateral knee arthroplasty presented with acute right-knee inflammation and gait impairment. Blood tests showed inflammatory response and knee x-ray revealed no prosthesis loosening. Irrigation and debridement was performed. Gram-positive cocci were obtained from cultures, and then biochemical and molecular identification revealed L. mesenteroides. Susceptibility and biofilm production were performed. The patient was treated with IntraVenous (IV) Ceftriaxone for ten days and was then switched to Amoxicillin-Clavulanate for 3 months with clinical and laboratory success. CONCLUSIONS: Microbiology diagnosis of fastidious microorganisms is mandatory to treat periprosthetic joint infections adequately. L. mesenteroides may infect non-immunocompromised persons; however, treatment guidelines are lacking.