The Evolution of Antimicrobial Resistance in Mexico During the Last Decade: Results from the INVIFAR Group.

Background: Surveillance of antimicrobial resistance (AMR) requires an international approach with national and local strategies. Our aim was to summarize a retrospective 10-year report of antibiotic resistance of gram-positive and gram-negative bacteria in Mexico. Methods: A total of 46 centers from 22 states of Mexico participated. Databases of AMR from January 2009 to December 2018 were included for most species. The 10-year period was divided into five 2-year periods. Results: For Staphylococcus aureus, a decrease in resistance in all specimens was observed for erythromycin and oxacillin (p < 0.0001 for each). For Enterobacter spp., resistance to meropenem increased for urine specimens (p = 0.0042). For Klebsiella spp., increased drug resistance in specimens collected from blood was observed for trimethoprim/sulfamethoxazole, gentamicin, tobramycin (p < 0.0001 for each), meropenem (p = 0.0014), and aztreonam (p = 0.0030). For Acinetobacter baumannii complex, high drug resistance was detected for almost all antibiotics, including carbapenems, except for tobramycin, which showed decreased resistance for urine, respiratory, and blood isolates (p < 0.0001 for each), and for amikacin, which showed a decrease in resistance in urine specimens (p = 0.0002). An increase in resistance to cefepime was found for urine, respiratory, and blood specimens (p < 0.0001 for each). For Pseudomonas aeruginosa, aztreonam resistance increased for isolates recovered from blood (p = 0.0001). Conclusion: This laboratory-based surveillance of antibiotic resistance shows that resistance is increasing for some antibiotics in different bacterial species in Mexico and highlights the need for continuous monitoring of antibiotic resistance.

[Comparative study of the efficacy of larva therapy for debridement and control of bacterial burden compared to surgical debridement and topical application of an antimicrobial]. / Estudio comparativo de la eficacia de la larvaterapia (LT) para desbridar y controlar la carga bacteriana en úlceras venosas comparado con desbridamiento quirúrgico y aplicación de un antimicrobiano tópico.

Maggot debridement therapy (MDT) is the use of medical grade maggots of the fly Lucilia sericata for wound debridement. Recent observations show that MDT decreases bacterial burden as well. Venous ulcers are the most commonly seen in wound clinics and require, besides adequate treatment of venous hypertension, proper wound bed preparation with debri dement of necrotic tissue and control of potential infections. To evaluate the efficacy of MDT in venous ulcers a randomized controlled trial was designed to compare MDT to surgical debridement and topical application of silver sulfadiazine (SSD) in 19 patients for 4 weeks. The study variables were area reduction, wound bed characteristics, pain, odor, anxiety and bacterial burden using quantitative tissue biopsies. MDT was effective as surgical debridement associated with topical SDD in the debridement of the wound and in reducing its size. A significant difference was observed in the reduction of bacterial burden in favor of the MDT group. Odor and anxiety increased in the MDT group without any difference in the pain intensity between groups. In conclusion, this study suggests that MDT is as effective as surgical debridement for the debridement of necrotic tissue and promote wound healing in venous ulcers and better at reducing bacterial burden.

Identification and Characterization of Imipenem-Resistant Klebsiella pneumoniae and Susceptible Klebsiella variicola Isolates Obtained from the Same Patient.

Klebsiella variicola, a bacterium closely genetically related to Klebsiella pneumoniae, is commonly misidentified as K. pneumoniae by biochemical tests. To distinguish between the two bacteria, phylogenetic analysis of the rpoB gene and the identification of unique genes in both bacterial species by multiplex-polymerase chain reaction (PCR) provide the means to reliably identify and genotype K. variicola. In recent years, K. variicola has been described both as the cause of an intrahospital outbreak in a pediatric hospital, which resulted in sepsis in inpatients, and as a frequent cause of bloodstream infections. In the present study, K. pneumoniae and K. variicola were isolated from a unique patient displaying different antimicrobial susceptibility phenotypes and different genotypes of virulence determinants. Eight clinical isolates were obtained at different time intervals; all during a 5-month period. The isolates were identified as K. pneumoniae by an automated identification system. The clinical (biochemical test) and molecular (multiplex-PCR and rpoB gene) characterization identified imipenem resistance in the first six K. pneumoniae ST258 isolates, which encode the SHV-12 cephalosporinase and KPC-3 carbapenemase genes. The two last remaining isolates corresponded to susceptible K. variicola. The bacterial species showed a specific profile of virulence-associated determinants, specifically the fimA, fimH, and ecpRAB fimbrial-encoding genes identified only in K. pneumoniae isolates. However, the entb (enterobactin), mrkD (fimbrial adhesin), uge (epimerase), ureA (urease), and wabG (transferase) genes were shared between both bacterial species. Recent studies attribute a higher mortality rate to K. variicola than to K. pneumonia. This work highlights the identification of K. pneumoniae and the closely related K. variicola isolated from the same patient. The value of distinguishing between these two bacterial species is in their clinical significance, their different phenotypes and genotypes, and the fact that they can be isolated from the same patient.

Identification of virulence factors genes in Escherichia coli isolates from women with urinary tract infection in Mexico.

E coli isolates (108) from Mexican women, clinically diagnosed with urinary tract infection, were screened to identify virulence genes, phylogenetic groups, and antibiotic resistance. Isolates were identified by MicroScan4 system; additionally, the minimum inhibitory concentration (MIC) was assessed. The phylogenetic groups and 16 virulence genes encoding adhesins, toxins, siderophores, lipopolysaccharide (LPS), and invasins were identified by PCR. Phylogenetic groups distribution was as follows: B1 9.3%, A 30.6%, B2 55.6%, and D 4.6%. Virulence genes prevalence was ecp 98.1%, fimH 86.1%, traT 77.8%, sfa/focDE 74.1%, papC 62%, iutA 48.1%, fyuA 44.4%, focG 2.8%, sfaS 1.9%, hlyA 7.4%, cnf-1 6.5%, cdt-B 0.9%, cvaC 2.8%, ibeA 2.8%, and rfc 0.9%. Regarding antimicrobial resistance it was above 50% to ampicillin/sulbactam, ampicillin, piperacillin, trimethoprim/sulfamethoxazole, ciprofloxacin, and levofloxacin. Uropathogenic E. coli clustered mainly in the pathogenic phylogenetic group B2. The isolates showed a high presence of siderophores and adhesion genes and a low presence of genes encoding toxins. The high frequency of papC gene suggests that these isolates have the ability to colonize the kidneys. High resistance to drugs considered as first choice treatment such as trimethoprim/sulfamethoxazole and fluoroquinolones was consistently observed.

New tetratrichomonas species in two patients with pleural empyema.

Two unusual occurrences of pleural trichomonosis due to a new Tetratrichomonas species previously reported but not named were confirmed. In one patient, Trichomonas tenax and a Tetratrichomonas species were also detected in the oral cavity by molecular methods. We suggest that this new Tetratrichomonas species be named Tetratrichomonas empyemagena.

E. coli outbreak in a neonate intensive care unit in a general hospital in Mexico City.

Nosocomial infections are a major cause of morbidity and mortality among neonates admitted to neonatal intensive care units (NICUs). The aim of this paper was to describe an outbreak of Escherichia coli among infants admitted to the NICU of the General Hospital "Dr. Manuel Gea Gonzalez" in May of 2008. The isolated E. coli strains were identified using standard biochemical methods. The susceptibilities of these strains were analysed by determining their minimal inhibitory concentrations. Following this, their molecular relationships to each other were assessed by pulsed field gel electrophoresis (PFGE) analysis and corroborated by serology. Twelve E. coli strains were isolated from blood, urine, or indwelling catheter samples from five cases of preterm infants within a 3-day period. Patients were admitted to the NICU of the general hospital and, during the outbreak, developed sepsis caused by E. coli. For four of the patients, the average age was 23 days, while one patient was a 3-month-old infant. Prior to sepsis, the infants had received assisted ventilation and hyperalimentation through a central venous catheter. Two profiles were observed by PFGE; profile A was identified as the outbreak's cause and an outcome of cross-infection, while profile B showed genetic differences but serologically it was identified as part of the same serotype. We conclude that E. coli colonised the patients through horizontal transmission. A focal source of the microorganism in this outbreak was not identified, but cross-transmission through handling was the most probable route.

Outbreak of Candida parapsilosis in a neonatal intensive care unit: a health care workers source.

Nosocomial neonatal candidiasis is a major problem in infants, which require intensive therapy. The subjects of the present study were three preterm infants admitted to the neonatal intensive care unit of the General Hospital "Dr. Manuel Gea Gonzalez". The infants developed Candida parapsilosis infection on the mean age of 13.6 day of life. Prior to fungemia, infants had received assisted ventilation and hyperalimentation through central venous catheter. Sequence analysis of the internal transcribed spacer gene ruled out other Candida species and revealed that the eight isolates were C. parapsilosis. The isolates were examined based on their molecular relation by random amplified polymorphic DNA analysis. The profiles allowed the identification of two main genotypes of C. parapsilosis as the outbreak cause and as a result of the cross-infection with health care workers' hands. We conclude that C. parapsilosis commonly colonize through horizontal transmission due to the staff's noncompliance of hand hygiene procedures.

Brote epidémico por Serratia marcescens en un servicio de neonatología / Epidemic outoreank by Serratia marcescens in a neonatal care unit

Serratia marcecens, ha sido considerada responsable de epidemias en recién nacidos (RN). En este estudio se describen las características de un brote por este microorganismo, el cual se presentó entre febrero y abril de 1987 en un servicio de neonatología. Se detectaron 23 pacientes con septicemia, 14 de estos desarrollaron meningoencefalitis; otras localizaciones de infección fueron: flebitis, neumonía, conjuntivitis, abscesos dérmicos y onfalitis. Fallecieron 15 pacientes. Durante la investigación epidemiológica no fue posible encontrar una fuente ambiental común para explicar el brote; sin embargo, S. marcecens se aisló de punta de catéter, sondas nasogástricas, así como de cultivos de manos lo que hizo sospechar que la vía de transmisión de paciente a paciente fue a través de las manos del personal. El tracto gastrointestinal y respiratorio de los propios niños infectados resultó ser el reservorio más importante. Las medidas efectivas para el control de la epidemia y la interrupción de la diseminación de paciente a paciente fueron el lavado de manos adecuado, la antisepsia y el aislamiento de los R colonizados e infectados. Esta investigación demuestra que S. marcescens es un agente potencialmente paógeno que puede ser responsable de infecciones graves en el RN particularmente cuando se relajan las medidas de control epidemiológico

Infecciones nosocomiales en una unidad de pediatría / Nosocomial infections in a pediatric unit

En México, se han realizado pocos estudios sobre infecciones nosocomiales(IN) en hospitales de segundo nível, probablemente por la falta de infraestructura necesaria para apegarse a los lineamientos convencionales. Se diseñó un programa de vigilancia en el Hiospital General "Dr. Manuel Gea González", institución de segundo nível que no contaba con epidemiólogo hospitalario o enfermeras epidemiólogas. A fin de adaptarse a estas condiciones, se modificó el sistema de registro utilizado por otros investigadores. El estudio se realizó durante un período de seis meses (diciembre 1986 a mayo 1987), registrándose 189 episodios/604 egresos, dando una razón promedio de 31.3%, incidencia del 18% y una mortalidad asociada del 28.8%. En los meses de febrero a baril ocurrió una epidemia de septicemia y meningitis causada por Serratia marcescens. Se detectaron 26 casos con una mortalidad del 69%. Los resultados obtenidos contrastan significativamente con los de otras publicaciones, y subrayan la importancia de que cada hospital conozca su problema de IN y no extrapole de los reportes de otros autores. En nuestra unidad la información obtenida de la vigilancia epidemiológica permitió la formulación de acciones específicas dirigidas a controlar las IN y su morbimortalidad consecuente