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Guillermo Jose Vazquez-Rosas,1,2 Jocelin Merida-Vieyra,1 Gerardo Aparicio-Ozores,2 Antonino Lara-Hernandez,3 Agustin De Colsa,1,4 Alejandra Aquino-Andrade1 1Molecular Microbiology Laboratory, Instituto Nacional de Pediatria, Mexico City, Mexico; 2Medical Bacteriology Laboratory, Instituto Politecnico Nacional, Mexico City, Mexico; 3Bacteriology Laboratory, Instituto Nacional de Pediatria, Mexico City, Mexico; 4Department of Paediatric Infectious Diseases, Instituto Nacional de Pediatria, Mexico City, MexicoCorrespondence: Alejandra Aquino-AndradeMolecular Microbiology Laboratory, Instituto Nacional de Pediatria, Insurgentes Sur 3700-C, Col. Insurgentes Cuicuilco, Alcaldia Coyoacan, C.P. 04530, Mexico City, MexicoTel +52 55 1084-0900 Ext. 1859Email aaquinoa@pediatria.gob.mxPurpose: Staphylococcus aureus is one of the main causative agents of hospital-acquired (HA) infections. In Mexico, information about the characteristics of clinical S. aureus isolates is limited. Our aim was to characterize S. aureus strains obtained from blood cultures of paediatric patients treated in a tertiary care hospital.Materials and Methods: We analysed 249 S. aureus isolates over the period from 2006 to 2019, and their resistance profiles were determined. The isolates were classified into methicillin-resistant S. aureus (MRSA) or methicillin-sensitive S. aureus (MSSA). Staphylococcal cassettes chromosome mec (SCCmec) were detected. Virulence genes (cna, clfA, clfB, eta, etb, fnbA, fnbB, hla, pvl, sec, and tsst) were amplified, and their clonal relationships were established by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST) and clonal complex (CC) typing. We reviewed one hundred medical files to collect clinical information.Results: Thirty-eight percent of the isolates were MRSA and showed an expanded profile of resistance to other non-beta-lactam antibiotics, while MSSA strains presented a reduced resistance profile. SCCmec-II was the most frequent element (86.3%). Eight virulence factors were detected in MSSA and six in MRSA. The pvl gene was detected in four MRSA-SCCmec-IV isolates (P≤ 0.0001). MRSA isolates were distributed among 14 clones and were classified into 15 sequence types (ST); the most frequent was ST1011 (17%). The most common CC in MRSA was CC5 (69%, P≤ 0.0001), and in MSSA, it was CC30 (30%, P≤ 0.0001). Eighty-seven percent of MRSA isolates were HA-MRSA, and 13% were community-acquired MRSA (CA-MRSA). Of 21 HA-MRSA isolates, 17 had SCCmec-II, while two CA-MRSA isolates had SCCmec-IV. Of MSSA isolates, 77% were derived from HA infections and 23% from CA infections.Conclusion: MSSA isolates had more virulence factors. MRSA isolates were resistant to more non-beta-lactam antibiotics, and those with SCCmec-IV expressed a greater variety of virulence factors. Most S. aureus isolates belonged to CC5.Keywords: MSSA, MRSA, virulence factors, clonal complex, SCCmec-II, CC5

Jocelin Merida-Vieyra,1,2,* Alejandra Aquino-Andrade,3,* Deborah Palacios-Reyes,4 Chiharu Murata,5 Rosa Maria Ribas-Aparicio,2 Agustin De Colsa Ranero61Molecular Microbiology Laboratory, Instituto Nacional de Pediatria (INP), Mexico City, Mexico; 2Biological Production and Control Laboratory, Escuela Nacional de Ciencias Biológicas, Instituto Politecnico Nacional, Mexico City, Mexico; 3Molecular Microbiology Laboratory, INP, Mexico City, Mexico; 4Department of Pediatric Infectious Diseases, INP, Mexico City, Mexico; 5Research Methodology, INP, Mexico City, Mexico; 6Molecular Microbiology Laboratory, Department of Pediatric Infectious Diseases, INP, Mexico City, Mexico*These authors contributed equally to this workPurpose: Mycoplasma pneumoniae is an important cause of community-acquired pneumonia (CAP). Information on the prevalence of M. pneumoniae in pediatric patients with CAP in Mexico is limited. The aim of this study was to detect M. pneumoniae in hospitalized pediatric patients with CAP.Patients and methods: We performed a descriptive study in a tertiary-level pediatric reference center, obtaining 154 respiratory samples from patients under 18 years of age and diagnosed with CAP. M. pneumoniae was detected by real-time polymerase chain reaction (PCR) targeting the p1 and CARDS genes. Complete blood cell count, measurement of C-reactive protein and detection of IgM and IgG anti-P1 were performed. Clinical, epidemiological and radiological data of the patients were analyzed.Results: M. pneumoniae was detected by real-time PCR in 26.6% of the samples. 39% of the cases occurred during the spring season. A total of 83% of the patients with M. pneumoniae had some underlying disease; renal disease, autoimmune disease and primary immunodeficiencies had a significant association with M. pneumoniae CAP. Children under 6 years of age represented 53.7% of the cases. Fever and cough were the most frequent symptoms. IgM and IgG were positive in 1.9% and 14% of the patients, respectively. In the chest X-ray, 17.1% of the patients showed multifocal alveolar infiltrates pattern. The complications in this series were 26.8%. The mortality in this study was 4.9%.Conclusion: This is the first report in Mexico about M. pneumoniae as a causal agent of CAP in a tertiary care pediatric hospital using real-time PCR and serology. M. pneumoniae was responsible for 26.6% of the cases and was frequent in children under 6 years of age. In addition, we described the clinical presentation in patients with underlying diseases.Keywords: Mycoplasma pneumoniae, community-acquired pneumonia, pediatrics, Mexico

Atypical pneumonia is a term that was used originally in adult patients who had atypical pneumonia symptoms, usually with mild and benign courses, and were caused by agents such as Mycoplasma pneumoniae, Chlamydophila pneumoniae and Legionella pneumophila. In pediatric patients, the clinical and epidemiological aspects of M. pneumoniae pneumonia need special attention, because in some cases do not have benign courses and sometimes they have extrapulmonary manifestations. The diagnostic approach is complex and doing a differential diagnosis from other etiological agents is complicated. Recently, the emergence of macrolide resistance in some countries has been alarming. There are controversies regarding antibiotic treatment. Worldwide, several studies, particularly from Asian countries, had shown new data regarding the biological, clinical, epidemiological, radiological and therapeutic response of M. pneumoniae in pediatric patients. [ABSTRACT FROM AUTHOR]

Wastewater serves as a reservoir for antimicrobial-resistant bacteria. This study revealed the presence of carbapenem-resistant and carbapenemase-producing Gram-negative bacilli (GNB), established clonal relationships among isolates in hospital and municipal wastewater, and identified a high-risk clone in municipal wastewater. A total of 63 isolates of GNB were obtained, with Enterobacterales being the most frequently isolated group (62%). Carbapenemase-producing Lelliottia amnigena, Kluyvera cryocrescens, and Shewanella putrefaciens isolates were documented for the first time in Mexico. The detectableted carbapenemase genes were bla KPC (55%), bla NDM (12%), bla VIM-2 (12%), bla OXA-48 (4%), bla GES (2%), bla NDM-1 (2%), and bla NDM-5 (2%). Clonal relationships were observed among Klebsiella pneumoniae and Enterobacter spp. isolates, and remarkably the high-risk clone Escherichia coli ST361, carrying bla NDM-5 , was identified. This study demonstrates that wastewater harbours carbapenem-resistant and carbapenemase-producing bacteria, posing a public health threat that requires epidemiological surveillance., (© 2024. The Author(s).)

Chlamydophila pneumoniae is a cause of community-acquired pneumonia (CAP) and responsible for 1-2% of cases in paediatric patients. In Mexico, information on this microorganism is limited. The aim of this study was to detect C. pneumoniae using two genomic targets in a real-time PCR and IgM/IgG serology assays in paediatric patients with CAP at a tertiary care hospital in Mexico City and to describe their clinical characteristics, radiological features, and outcomes. A total of 154 hospitalized patients with diagnosis of CAP were included. Detection of C. pneumoniae was performed by real-time PCR of the pst and arg genes. Complete blood cell count, C-reactive protein measurement and IgM and IgG detection were performed. Clinical-epidemiological and radiological data from the patients were collected. C. pneumoniae was detected in 25 patients (16%), of whom 88% had underlying disease (P = 0.014). Forty-eight percent of the cases occurred in spring, 36% in girls, and 40% in children older than 6 years. All patients had cough, and 88% had fever. Interstitial pattern on chest-X-ray was the most frequent (68%), consolidation was observed in 32% (P = 0.002). IgM was positive in 7% and IgG in 28.6%. Thirty-six percent presented complications. Four percent died. A high proportion showed co-infection with Mycoplasma pneumoniae (64%). This is the first clinical report of C. pneumoniae as a cause of CAP in Mexican paediatric patients, using two genomic target strategy and serology. We found a frequency of 16.2% with predominance in children under 6 years of age. In addition; cough and fever were the most common symptoms. Early detection of this pathogen allows timely initiation of specific antimicrobial therapy to reduce development of complications. This study is one of the few to describe the presence of C. pneumoniae in patients with underlying diseases., (© 2023. The Author(s).)

Staphylococcus aureus is the main aetiologic agent of osteoarticular infections (OAIs) in paediatric patients. The aim of this prospective unicenter study was to describe the phenotypic and genotypic characteristics of S. aureus isolates obtained from OAIs in paediatric patients admitted to tertiary care hospital. Through a surveillance program called OsteoCode , a multidisciplinary team was created and we identified 27 patients with OAIs caused by S. aureus from 2019 to 2021. The susceptibility profile, virulence factors, biofilm formation, pulsed-field gel electrophoresis (PFGE), clonal complex (CC) and sequence type (ST) were determined. In addition, the clinical characteristics and evolution of the patients presented six months after the diagnosis of OAIs were described. Ninety-two percent of the isolates were methicillin-sensitive S. aureus (MSSA). In methicillin-resistant S. aureus (MRSA), SCC mec- II and SCC mec- V were detected. The pvl gene was only observed in MSSA (18.5%) and was associated with highest fever ( p =0.015), multiple localization ( p= 0.017), and soft tissue sites of infection beyond the bone (pyomyositis, pulmonary abscess) ( p= 0.017). Biofilm formation was detected in 55.6% of isolates. The most common CC were CC5 and CC30 which represent the most common linages for bone and joint infections worldwide. The isolates were distributed in different STs, and ST672 was predominant. MRSA were associated with a longer duration of intravenous treatment and a prolonged hospital stay ( p= 0.023). Recurrent infection occurred in five children and orthopaedic complications in 33.3% of patients. This is the first study that reflects the epidemiology of S. aureus in OAIs in paediatric patients in Mexico; a clear predominance of MSSA distributed in different STs was observed. Our findings highlight that a multidisciplinary team is required for the diagnosis and treatment of OAIs., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Aguilar-Gómez, Merida-Vieyra, Isunza-Alonso, Morales-Pirela, Colín-Martínez, Juárez-Benítez, García de la Puente and Aquino-Andrade.)

Background: The aim of this study was to detect CMY-type beta-lactamases in E. coli isolates obtained from paediatric patients., Methods: In total, 404 infection-causing E. coli isolates resistant to third and fourth generation cephalosporins (3GC, 4GC) were collected from paediatric patients over a 2 years period. The identification and susceptibility profiles were determined with an automated microbiology system. Typing of bla CMY and other beta-lactamase genes (bla TEM , bla SHV , bla CTX-M , bla VIM , bla IMP , bla KPC , bla NDM , bla OXA and bla GES ) was realized by PCR and sequencing. Phenotypic detection of AmpC-type enzymes was performed using boronic acid (20 mg/mL) and cloxacillin (20 mg/mL) as inhibitors, and the production of extended-spectrum beta-lactamases was determined with the double-disk diffusion test with cefotaxime (CTX) and ceftazidime (CAZ) discs alone and in combination with clavulanic acid. The CarbaNP test and modified carbapenem inhibition method (mCIM) were used for isolates with decreased susceptibility to carbapenems. The clonal origin of the isolates was established by pulsed-field gel electrophoresis (PFGE), phylotyping method and multilocus sequence typing., Results: CMY-type beta-lactamases were detected in 18 isolates (4.5%). The allelic variants found were CMY-2 (n = 14) and CMY-42 (n = 4). Of the E. coli strains with CMY, the AmpC phenotypic production test was positive in 11 isolates with cloxacillin and in 15 with boronic acid. ESBL production was detected in 13 isolates. Coexistence with other beta-lactamases was observed such as CTX-M-15 ESBL and original spectrum beta-lactamases TEM-1 and TEM-190. In one isolate, the CarbaNP test was negative, the mCIM was positive, and OXA-48 carbapenemase was detected. Phylogroup A was the most frequent (n = 9) followed by B2, E and F (n = 2, respectively), and through PFGE, no clonal relationship was observed. Eleven different sequence types (ST) were found, with ST10 high-risk clone being the most frequent (n = 4). Seventy-two percent of the isolates were from health care-associated infections; the mortality rate was 11.1%., Conclusions: This is the first report in Mexico of E. coli producing CMY isolated from paediatric patients, demonstrating a frequency of 4.5%. In addition, this is the first finding of E. coli ST10 with CMY-2 and OXA-48.

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., Competing Interests: The authors have declared that no competing interests exist.

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.

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., Competing Interests: The authors have declared that no competing interests exist.