Carbapenemase-producing Enterobacteriaceae in Mexico: report of seven non-clonal cases in a pediatric hospital.

BACKGROUND: Carbapenemases-producing Enterobacteriaceae (CPE) are a worldwide public health emergency. In Mexico, reports of CPE are limited, particularly in the pediatric population. Here, we describe the clinical, epidemiological, and molecular characteristics of seven consecutive cases in a third-level pediatric hospital in Mexico City over a four-month period during 2016. RESULTS: The Enterobacteriaceae identified were three Escherichia coli strains (producing OXA-232, NDM-1 and KPC-2), two Klebsiella pneumoniae strains (producing KPC-2 and NDM-1), one Klebsiella oxytoca strain producing OXA-48 and one Enterobacter cloacae strain producing NDM-1. The majority of patients had underlying disesases, three were immunocompromised, and three had infections involved the skin and soft tissues. Half patients died as a result of CPE infection. CONCLUSIONS: This study represents the first report of E. coli ST131-O25b clone producing NDM-1 in Latin America. In addition, this study is the first finding of K. oxytoca producing OXA-48 and E. coli producing OXA-232 in Mexican pediatric patients.

[Microsporidia in pediatric patients with leukemia or limphoma]. / Microsporidiosis en pacientes pediátricos con leucemia o linfoma.

INTRODUCTION: Microsporidia are intracellular micro-organisms, characterized by mature spores with chitin walls and by one extrusive polar tube through which they pour their sporoplasm to the host cells. In immunocompromised patients, Enterocytozoon bieneusi and Encephalitozoon intestinalis produce diarrhea and systemic dissemination. In Mexico there is not information about microsporidia in children with cancer. OBJECTIVE: The aim of this pilot study was to investigate the presence of microsporidia species in pediatric patients with leukemia or lymphoma. MATERIAL AND METHODS: We obtained fecal samples from thirteen patients. The samples were processed to detect microsporidia by both modified Ziehl-Neelsen and clacofluor white stains, DNA was isolated to amplify rRNA specific sequences, to identify E. bieneusi, E. intestinalis, E. cuniculi and E. hellem by DNA polymerase chain reaction (PCR). Other parasites and pathogenic bacteria were also tested. RESULTS: Based on morphologic traits 7/13 samples were found positives to microsporidia and 6/10 by PCR. Was identified E. bieneusi in three patients with leukemia and one with lymphoma, another two children with leukemia were infected with E. intestinalis. Almost all children were high-risk patients and in phase of re-induction, consolidation or with many chemotherapy treatments. All the patients with microspiridia did not present diarrhea at the moment of the sampling; however, in two children with diarrhea it was found Cyclospora cayetanensis. Also we obtained feces from five patients' mothers and microsporidia spores were identified by stain in all of them and by PCR it was diagnosed the species in three of them. CONCLUSION: It was demonstrated that the feces of patients with leukemia or lymphoma had microsporidia, therefore is necessary to know the prevalence of these microorganisms and to analyze their impact in evolution of cancer patients.

Genetic and phenotypic determinants of resistance to antibiotics in Aeromonas spp., strains isolated from pediatric patients.

INTRODUCTION: Intestinal and extraintestinal infections by Aeromonas spp., remain controversial, due to the existence of healthy carriers of Aeromonas spp. In children under five years old, the diarrhea of infectious origin constitutes the second cause of mortality and remains a major concern for public health. The aim of this work was to detect the pheno/genotype of ß-lactamases and class 1 integrons in Aeromonas spp., strains isolated from pediatric patients in a tertiary referral hospital in Mexico. METHODOLOGY: Sixty-six strains of Aeromonas spp., were isolated from clinical samples of pediatric origin and were identified by RFLP-PCR 16S rRNA. Resistance phenotype according to CLSI, genetic and phenotypic detection of extended-spectrum ß-lactamases (ESBL) and metallo-b-lactamases (MBL) was performed. Finally, characterization of class 1 integrons was performed. RESULTS: Aeromonas spp., strains of diarrheic origin were more predominant. A wide heterogeneity was detected, where A. caviae was the predominant specie. Second-generation cephalosporins, fluoroquinolones, and nitrofurans had best antimicrobial activity; moreover, antibiotics of the ß-lactamic and lincosamides families showed lower inhibitory activity. Phenotypically, prevalences of 4.55% and 3.03% were detected for MBL (intestinal origin) and ESBL (extraintestinal origin), respectively. blaIMIS-cphA and blaTEM-1 genes, and nineteen class 1 integrons carrying two variants of cassettes corresponding to adenylyl transferases (aadA), and dihydrofolate reductases (dfrA). Monogenic array with aadA1 cassette was predominantly. CONCLUSIONS: ESBL and class 1 integrons, in Aeromonas collected from pediatric patients, determines a major detection challenge for the clinical microbiology laboratory and represents a remarkable epidemiological risk of nosocomial spread of multidrug-resistant determinants.

First clinical isolate of Escherichia coli harboring mcr-1 gene in Mexico.

Our aim in this report was to describe the characteristics of the first clinical isolate of Escherichia coli (EC-PAG-733) harboring the mcr-1 gene found in Mexico. This isolate was obtained from a fecal sample from a young child with an oncological condition. We obtained the whole-genome sequence using next-generation sequencing and analyzed the sequence by bioinformatics tools. EC-PAG-733 was resistant to third- and fourth-generation cephalosporins and was susceptible to all carbapenems and amikacin; it was also resistant to ciprofloxacin, levofloxacin, gentamicin and colistin at a minimum inhibitory concentration (MIC) of 4 µg/mL. This isolate was classified as O11:H25-ST457. EC-PAG-733 harbored an ESBL type CTX-M-55 as well as several virulence factors that have been associated with Enteroaggregative Escherichia coli (EAEC). The mcr-1 gene was located within an IncI2 plasmid. The results of this whole genome shotgun project were deposited in DDBJ/ENA/GenBank under the accession number QKXE00000000.

Nosocomial, Multidrug-Resistant Klebsiella pneumoniae Strains Isolated from Mexico City Produce Robust Biofilms on Abiotic Surfaces but Not on Human Lung Cells.

BACKGROUND: Klebsiella pneumoniae (Kpn) strains are a leading cause of hospital-acquired infections, including ventilator-associated pneumonia. Resistance to antibiotics, biofilm formation, and the production of certain fimbriae play an important role in the pathogenesis. AIM: We investigated the genetic relatedness, antibiotic resistance, virulence potential, and ability to form biofilms of Kpn strains isolated from hospital-acquired infections (n = 76). Strains were isolated at three major hospitals serving the largest metropolitan urban area in Mexico City, Mexico. RESULTS: Enterobacterial repetitive intergenic consensus (ERIC)-PCR demonstrated that clonal groups predominate in each hospital. Selected strains chosen from clonal groups (n = 47) were multidrug resistant (MDR, 83%), although the majority (∼70%) were susceptible to carbapenems. All strains produced robust biofilms on abiotic surfaces, and ∼90% harbored adhesin genes fimH, mrkA, and ecpA. The ultrastructure of biofilms was further studied by high-resolution confocal microscopy. The average height of Kpn biofilms on abiotic surfaces was ∼40 µm. We then assessed formation of biofilms on human lung cells, as a surrogate of lung infection. While Kpn strains formed robust biofilms on abiotic surfaces, studies on lung cells revealed attachment to human cells but scarce formation of biofilms. Gene expression studies revealed a differential temporal expression of an adhesin (ecpA) and a capsule (galF) gene when biofilms were formed on different substrates. CONCLUSIONS: Kpn strains isolated from nosocomial infections in Mexico City are MDR, although the majority are still susceptible to carbapenems and form more robust biofilms on polystyrene in comparison to those formed on human cells.

Resistance of uropathogenic bacteria to first-line antibiotics in mexico city: A multicenter susceptibility analysis.

UNLABELLED: Abstract. BACKGROUND: Growing antibiotic resistance demands the constant reassessment of antimicrobial efficacy, particularly in countries with wide antibiotic abuse, where higher resistance prevalence is often found. Knowledge of resistance trends is particularly important when prescribing antibiotics empirically, as is usually the case for urinary tract infections (UTIs). Currently, in Mexico City, ampicillin, cotrimoxazole (trimethoprim/sulfamethoxazole), and ciprofloxacin are used as "first-line" antibiotic treatment for UTI. OBJECTIVE: The aim of this study was to analyze the resistance of bacterial isolates to antibiotics, with a focus on first-line antibiotics, in Mexican pediatric patients and sexually active or pregnant female outpatients. METHODS: In this multicenter susceptibility analysis, bacterial isolates from urine samples collected from pediatric patients and sexually-active or pregnant female outpatients presenting with acute, uncomplicated UTIs in Mexico City from January 2006 through June 2006, were included in the study. Samples were tested for susceptibility to 10 antibiotics by the disk-diffusion method. RESULTS: Four-hundred and seventeen bacterial isolates were derived from sexually active or pregnant female outpatients (324 Escherichia coli) and pediatric patients (93 Klebsiella pneumoniae). We found a high prevalence of resistance towards the drugs used as "first-line" when treating UTIs: ampicillin, cotrimoxazole, and ciprofloxacin (79%, 60%, and 24% resistance, respectively). Ninety-eight percent of K pneumoniae isolates were resistant to ampicillin, whereas 66% of the E coli isolates were resistant to cotrimoxazole. Resistance towards third-generation cephalosporins was also high (6%-8% of E coli and 10%-28% of K pneumoniae). This was possibly caused by chromosomal ß-lactamases, as 30% of all isolates were also resistant to amoxicillin/clavulanate. In contrast, 98% of the E coli isolates and 84% of the K pneumoniae strains (96% of all isolates) were found to be susceptible to nitrofurantoin, which has been in clinical use for much longer than most other drugs in this study. CONCLUSION: In these urine samples from laboratories in Mexico City, resistance of K pneumoniae and E coli isolates to first-line treatment (ampicillin, cotrimoxazole, or ciprofloxacin) of UTI was high, whereas most E coli and K pneumoniae isolates were susceptible to nitrofurantoin and the fourth-generation cephalosporin cefepime. (Curr Ther Res Clin Exp. 2007;68:120-126) Copyright © 2007 Excerpta Medica, Inc.

First Report of Group CTX-M-9 Extended Spectrum Beta-Lactamases in Escherichia coli Isolates from Pediatric Patients in Mexico.

The aim of this study was to identify the presence of group CTX-M-9 extended spectrum beta-lactamases (ESBL) in clinical Escherichia coli isolates from pediatric patients. A total of 404 non-repeated positive ESBL E. coli isolates were collected from documented clinical infections in pediatric patients over a 2-year period. The identification and susceptibility profiles were determined using an automated system. Isolates that suggested ESBL production based on their resistance profiles to third and fourth generation cephalosporin and monobactam were selected. ESBL production was phenotypically confirmed using a diffusion method with cefotaxime and ceftazidime discs alone and in combination with clavulanic acid. blaESBL gene identification was performed through PCR amplification and sequencing. Pulsed Field Gel Electrophoresis (PFGE) and Multilocus Sequence Typing (MLST) were performed to establish the clonal relationships of the E. coli isolates. CTX-M-9-type ESBLs were detected in 2.5% of the isolates. The subtypes corresponded to blaCTX-M-14 (n = 4) and blaCTX-M-27 (n = 6). Additionally, coexistence with other beta-lactamases was observed. A clonal relationship was established in three isolates; the rest were classified as non-related. We found seven different sequence type (ST) in CTX-M-9- producing E. coli isolates. ST38 was the most frequent. This study is the first report in Mexico to document the presence of group CTX-M-9 ESBLs in E. coli isolates from pediatric patients.

Streptococcus pneumoniae as cause of infection in infants less than 60 days of age: serotypes and antimicrobial susceptibility.

OBJECTIVE: The aim of this study was to determine the distribution of serotypes and the antimicrobial susceptibilities of Streptococcus pneumoniae clinical isolates causing invasive and non-invasive disease in children aged ≤60 days in hospitals in Mexico. METHODS: A 15-year retrospective study was conducted for the period 2000 to 2014. Pneumococcal clinical isolates were serotyped by Quellung reaction, and antimicrobial susceptibility testing was performed with the broth microdilution method. RESULTS: A total of 126 pneumococcal isolates were collected. Pneumonia was the most frequent diagnosis (40.5%), followed by meningitis (29.4%), septicemia (16.7%), and other clinical entities, including otitis media and conjunctivitis (13.5%). The most frequent serotypes before the introduction of heptavalent pneumococcal conjugate vaccine (PCV7) were 19F, 23F, 7F, and 35B. Serotypes 3, 6A, 10A, 12F, and 15A/B increased after the introduction of PCV7. Serotype 19A was isolated most frequently in the pneumonia and meningitis cases only after the introduction of PCV7, and it displayed a high resistance to penicillin. CONCLUSIONS: Although the number of infections in infants aged ≤60 days was low, such infections were not unusual events. New vaccination strategies should be evaluated to limit the risks in this age group.

Neisseria meningitidis and Streptococcus pneumoniae as leading causes of pediatric bacterial meningitis in nine Mexican hospitals following 3 years of active surveillance.

OBJECTIVES: Meningococcal meningitis is reported as a rare condition in Mexico. There are no internationally published studies on bacterial causes of meningitis in the country based on active surveillance. This study focuses on finding the etiology of bacterial meningitis in children from nine Mexican Hospitals. METHODS: From January 2010 to February 2013, we conducted a three years of active surveillance for meningitis in nine hospitals throughout Mexico. Active surveillance started at the emergency department for every suspected case, and microbiological studies confirmed/ruled out all potentially bacterial pathogens. We diagnosed based on routine cultures from blood and cerebrospinal fluid (not polymerase chain reaction or other molecular diagnostic tests), and both pneumococcal serotyping and meningococcal serogrouping by using standard methods. RESULTS: Neisseria meningitidis was the leading cause, although 75% of cases occurred in the northwest of the country in Tijuana on the US border. Serogroup C was predominant. Streptococcus pneumoniae followed Neisseria meningitides, but was uniformly distributed throughout the country. Serotype 19A was the most incident but before universal implementation of the 13-valent pneumococcal conjugate vaccine. Other bacteria were much less common, including Enterobacteriaceae and Streptococcus agalactiae (these two affecting mostly young infants). CONCLUSIONS: Meningococcal meningitis is endemic in Tijuana, Mexico, and vaccination should be seriously considered in that region. Continuous universal vaccination with the 13-valent pneumococcal conjugate vaccine should be nationally performed, and polymerase chain reaction should be included for bacterial detection in all cultures - negative but presumably bacterial meningitis cases.

Draft Genome Sequence of Aeromonas caviae Strain 429865 INP, Isolated from a Mexican Patient.

Aeromonas caviae is an emerging human pathogen. Here, we report the draft genome sequence of Aeromonas caviae strain 429865 INP which shows the presence of various putative virulence-related genes.

Incidencia de Salmonella, Shigella y Escherichia coli enteropatógena, 1986-1993, en el Instituto Nacional de Pediatría / Incidence of Salmonella, Shigella y enteropathogene Escherichia coli, 1986-1993, at the Instituto Nacional de Pediatría

La gastroenteritis infecciosa constituye uno de los principales problemas de salud en casi todos los países de la América Latina. La Organización Mundial de la Salud reporta a las enfermedades diarreicas como una de las tres principales causas de defunsión en niños menores de 5 años, su etiología puede ser bacteriana, viral o parasitaria. Entre los agentes bacterianos se encuentran con mayor frecuencia especies de Salmonella, Shigella y E. coli enteropatógena y otras de menor frecuencia, como lo son Yersinia, Compylobacter, Plesiomonas, Aeromonas y Vibrio. El presente trabajo se ralizó con el fin de detectar a los agentes infecciosos clásicos (E. coli enteropatógena, Shigella y Salmonella). Durante 8 años se analizaron 22 519 muestras de materia fecal de pacientes del Instituto Nacional de Pediatría, resultado E. coli enteropatógena como la más frecuente con un 7 por ciento, seguida de Salmonella con 6 por ciento y Shigella 3 por ciento. Los serotipos más frecuentes de E. coli fueron 0111, 026 y 055, para Salmonella se observó el serogrupo B y en Shigella el serogrupo B (S. flexneri) también fue el más frecuente. Se observó infección múltiple en un 0.27 por ciento, Salmonella presentó resistencia a ampicilina, cefalotina y cloranfenicol. Shigella fue resistente a ampicilina, cefalotina, piperacilina y trimetoprim/sulfametoxasol