Multidrug-Resistant Staphylococcus sp. and Enterococcus sp. in Municipal and Hospital Wastewater: A Longitudinal Study

The objective of the study was to detect multidrug-resistant Staphylococcus sp. and Enterococcus sp. isolates in municipal and hospital wastewater and to determine their elimination or persistence after wastewater treatment. Between August 2021 and September 2022, raw and treated wastewater samples were collected at two hospital and two community wastewater treatment plants (WWTPs). In each season of the year, two treated and two raw wastewater samples were collected in duplicate at each of the WWTPs studied. Screening and presumptive identification of staphylococci and enterococci was performed using chromoagars, and identification was performed with the Matrix Assisted Laser Desorption Ionization Time of Flight mass spectrometry (MALDI-TOF MS®). Antimicrobial susceptibility was performed using VITEK 2® automated system. There were 56 wastewater samples obtained during the study period. A total of 182 Staphylococcus sp. and 248 Enterococcus sp. were identified. The highest frequency of Staphylococcus sp. isolation was in spring and summer (n = 129, 70.8%), and for Enterococcus sp. it was in autumn and winter (n = 143, 57.7%). Sixteen isolates of Staphylococcus sp. and sixty-three of Enterococcus sp. persisted during WWTP treatments. Thirteen species of staphylococci and seven species of enterococci were identified. Thirty-one isolates of Staphylococcus sp. and ninety-four of Enterococcus sp. were multidrug-resistant. Resistance to vancomycin (1.1%), linezolid (2.7%), and daptomycin (8.2%/10.9%%), and a lower susceptibility to tigecycline (2.7%), was observed. This study evidences the presence of Staphylococcus sp. and Enterococcus sp. resistant to antibiotics of last choice of clinical treatment, in community and hospital wastewater and their ability to survive WWTP treatment systems.

Diagnosis of bacterial meningitis caused by Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae using a multiplex real-time PCR technique

Bacterial meningitis is one of the diseases that, despite the introduction of several vaccines, remains a serious public health concern. Streptococcus pneumoniae (Spn), Neisseria meningitidis (Nm), and Haemophilus influenzae (Hi) are responsible for most cases diagnosed in children, adolescents, and adult population. Rapid, sensitive, and specific laboratory assays are critical for effective diagnosis and treatment, particularly in countries like Mexico in which culture positivity rates are very low due to the use of antibiotics prior to sample collection and to delay in transporting samples to the laboratory. The aim of this study was to evaluate the use of real-time polymerase chain reaction (RT-PCR) of cerebrospinal fluid (CSF) as a rapid diagnostic test for bacterial meningitis and compare these results with bacterial culture in three general hospitals in Mexico. During a 5-year period (2014-2018), a total of 512 CSF samples obtained from patients in whom infectious meningitis was suspected as initial clinical diagnosis were tested with RT-PCR with species-specific targets for the three pathogens. For Spn, 5.07% samples were RT-PCR positive; 0.39% for Nm and none for Hi. Only five RT-PCR Spn positive samples had a positive culture. Sensitivity and specificity estimates for RT-PCR are 100% and 95.46%, respectively. DNA amplification methods can provide better sensitive diagnostic tests than the reference standard, which is culture, particularly when antimicrobial treatment is initiated before clinical samples can be obtained.

Antimicrobial resistance: One Health approach

In this research, a review of antimicrobial resistance (AMR) is conducted as part of the One Health approach. A review of publications, which included “antimicrobial resistance” and “One Health,” was conducted. Among the global health problems, AMR is the one that most clearly illustrates the One Health approach. AMR is a critical global problem affecting humans, the environment, and animals. This is related to each of these three components due to the irresponsible and excessive use of antimicrobials in various sectors (agriculture, livestock, and human medicine). Improper management of antimicrobials, inadequate control of infections, agricultural debris, pollutants in the environment, and migration of people and animals infected with resistant bacteria facilitate the spread of resistance. The study aimed to analyze the problem of AMR from a health perspective to analyze the different actors involved in One Health.

Metodología de la Encuesta Nacional de Salud y Nutrición 2021

Objetivo. Describir el diseño de la Encuesta Nacional de Salud y Nutrición 2021 (Ensanut 2021). Material y métodos. La Ensanut 2021 es una encuesta probabilística de hogares que forma parte de la serie de Ensanut Continua 2020-2024. En esta ocasión se describen el alcance, el muestreo, la medición y la organización logística. Resultados. Se planea obtener al menos 12 060 entrevistas de hogar completas a nivel nacional y 9 837 muestras para determinar seropositividad a SARS-CoV-2 a nivel nacional. Conclusiones. La Ensanut 2021 permitirá realizar inferencias regionales sobre la prevalencia de seropositividad a SARS-CoV-2 y también acumular información para realizar inferencias estatales en el año 2024.

Estimating Bordetella pertussis seroprevalence in adolescents and young adults in Mexico using the 2012 National Health and Nutrition Survey (ENSANUT)

BACKGROUND

Low vaccination rates and under-detection of pertussis infections in adolescents and young adults have an impact on the transmission of pertussis to infants. In this study, the proportion of adolescents and young adults with IgG antibodies against B. pertussis antigens, representing recent infection or vaccination, was estimated in a population-based probabilistic survey in Mexico.

METHODS

Sera and data from 1,581 subjects, including 1,102 adolescents and 479 young adults (10-19 and 20-25 years old, respectively) randomly selected from Mexico's 2012 National Health and Nutrition Survey, were analyzed. IgG antibodies against pertussis toxin (PT) were measured with the CDC/FDA ELISA. A subset of 234 samples was additionally tested with Bp-IgG PT ELISA kit (EUROIMMUN AG, Lubeck, Germany). Threshold values from corresponding test kits were used to identify recent infection or vaccination.

RESULTS

Overall anti-PT IgG seroprevalence was 3.9% (95% CI: 2.3-6.3); 3.1% (95% CI: 1.9-5.0) in adolescents, and 4.9% (95% CI: 2.2-11) in young adults. Seroprevalence did not significantly vary by sex, socioeconomic status, region or rural/urban location. Compared to the CDC/FDA ELISA, the EUROIMMUN test showed a 76% sensitivity and 88% specificity. The weighted estimates represent a considerable burden of recent infection in adolescents and young adults; however, most adolescents and adults were seronegative and, therefore, susceptible to pertussis infection.

CONCLUSION

Since booster vaccination to B. pertussis after toddlerhood is not recommended in the Mexican national policy, anti-PT IgG seropositivity may be reasonably attributed to recent infection. Assessing pertussis seroprevalence requires careful consideration of the diagnostic test threshold interpretation and epidemiological model used.

The hidden burden of Chikungunya in central Mexico: results of a small-scale serosurvey

OBJECTIVE

To estimate the seroprevalence of CHKV antibodies and assess correlates of seropositivity at a small geographical scale.

MATERIALS AND METHODS

A community-based serosurvey of 387 households in Puente de Ixtla, Morelos (central Mexico). Serum IgG antibodies to CHKV were detected by immunoassay.

RESULTS

From 27 April to 29 May 2016, we interviewed and collected blood samples from 387 individuals at the same number of households. A total of 114 (29.5%) participants were seropositive to CHK, 36 (31.6%) of them reported no symptoms of CHKV infection within 12 months before the survey.

CONCLUSIONS

The estimated seroprevalence to CHKV antibodies was higher than expected by the small number of confirmed cases of CHKV infection reported in Mexico by the National Surveillance System.

Risk factors for extended-spectrum b-lactamases-producing Escherichia coli urinary tract infections in a tertiary hospital

Objective. To assess the risks factors for urinary tract infections (UTIs) caused by Extended-Spectrum Beta-Lactamases (ESBLs)-producing E. coli and the molecular characterization of ESBLs. Materials and methods. A case-control study was performed to identify risk factors in consecutively recruited patients with UTIs caused by ESBLs or non-ESBLs-producing E. coli in a tertiary hospital in Mexico. Results. ESBLs-producing E. coli were isolated from 22/70 (31%) patients with E. coli UTIs over a three month period. All isolates were resistant to cephalosporins and quinolones but susceptible to carbapenems, amikacin and nitrofurantoin. Prior antibiotic treatment with more than two antibiotic families (OR=6.86; 95%CI 1.06-157.70; p=0.028), recurrent symptomatic UTIs (OR=5.60; 95%CI 1.88-17.87; p=0.001) and previous hospitalization (OR=5.06; 95%CI 1.64-17.69;p=0.002) were significant risk factors. Sixteen isolates harbored the beta-lactamase (bla)CTX-M-15 gene and five the blaTEM-1 gene. Conclusions. One of every three patients presented UTIs with ESBLs-producing beta-lactams and fluoroquinolone resistant E. coli. Risk factors and resistance patterns must be taken into account for developing antibiotic use policies in these settings

Salmonella downregulates Nod-like receptor family CARD domain containing protein 4 expression to promote its survival in B cells by preventing inflammasome activation and cell death

Salmonella infects and survives within B cells, but the mechanism used by the bacterium to promote its survival in these cells is unknown. In macrophages, flagellin secreted by Salmonella activates the Nod-like receptor (NLR) family CARD domain containing protein 4 (NLRC4) inflammasome, leading to the production of IL-1β and pyroptosis of infected cells. In this study, we demonstrated that the NLRC4 inflammasome is functional in B cells; however, in Salmonella-infected B cells, IL-1β secretion is prevented through the downregulation of NLRC4 expression. A functional Salmonella pathogenicity island 1 type III secretion system appears to be required for this process. Furthermore, infection induces Yap phosphorylation and promotes the interaction of Yap with Hck, thus preventing the transcriptional activation of NLRC4. The ability of Salmonella to inhibit IL-1β production also prevents B cell death; thus, B cells represent an ideal niche in which Salmonella resides, thereby promoting its persistence and dissemination.

Salmonella infects B cells by macropinocytosis and formation of spacious phagosomes but does not induce pyroptosis in favor of its survival

We have previously reported that Salmonella infects B cells and survives within endosomal-lysosomal compartments. However, the mechanisms used by Salmonella to enter B cells remain unknown. In this study, we have shown that Salmonella induces its own entry by the induction of localized ruffling, macropinocytosis, and spacious phagosome formation. These events were associated with the rearrangement of actin and microtubule networks. The Salmonella pathogenesis island 1 (SPI-1) was necessary to invade B cells. In contrast to macrophages, B cells were highly resistant to cell death induced by Salmonella. These data demonstrate the ability of Salmonella to infect these non-professional phagocytic cells, where the bacterium can find an ideal intracellular niche to support persistence and the possible dissemination of infection.

Outbreak of nosocomial sepsis and pneumonia in a newborn intensive care unit by multiresistant extended-spectrum beta-lactamase-producing Klebsiella pneumoniae: high impact on mortality

We describe a case-control study of a small outbreak of nosocomial sepsis and pneumonia with high mortality due to clonal dissemination of a multiresistant Klebsiella pneumoniae in the neonatal intensive care unit of a Mexican institution. Our study helped to change nosocomial infection control policy in this hospital.

Spacious phagosome formation within mouse macrophages correlates with Salmonella serotype pathogenicity and host susceptibility

Light microscopic studies indicated a correlation between the virulence for mice of different Salmonella serotypes and the ability to form or maintain spacious phagosomes (SP) within mouse macrophages. Although Salmonella typhimurium induced membrane ruffling, macropinocytosis, and SP formation in macrophages from BALB/c mice, serotypes which are nonpathogenic for mice produced markedly fewer SP. SP formation correlated with both serotype survival within mouse macrophages and reported lethality for mice. Time-lapse video microscopy demonstrated that the human pathogen S. typhi induced generalized macropinocytosis and SP formation in human monocyte-derived macrophages, indicating a similar morphology for the initial phases of this host-pathogen interaction. In contrast to bone marrow-derived macrophages from BALB/c mice, macrophages from S. typhimurium-resistant outbred (CD-1) and inbred (CBA/HN) mice did not initiate generalized macropinocytosis after bacterial infection and formed markedly fewer SP. These deficiencies were not due to the Ihy resistance genotype of these mice, as macrophages from mice that were congenic except for the Ihy locus demonstrated equal SP formation in response to S. typhimurium. The observation that S. typhimurium-resistant CD-1 and CBA/HN mice are deficient in the ability to form and/or maintain SP indicates that a variable host component is important for SP formation and suggests that the ability to induce or form SP affects susceptibility to S. typhimurium. When serotypes nonpathogenic for mice were used to infect BALB/c macrophages, or when CD-1 or CBA/HN mouse macrophages were infected by S. typhimurium, some of the SP that formed shrank within seconds. This rapid shrinkage suggests that SP maintenance is also important for S. typhimurium survival within macrophages. These studies indicate that both host and bacterial factors contribute to SP formation and maintenance, which correlate with Salmonella intracellular survival and the ability to cause lethal enteric (typhoid) fever.

Characterization of the Salmonella typhimurium pagC/pagD chromosomal region

The PhoP/PhoQ two-component system regulates Salmonella typhimurium genes that are essential to bacterial virulence and survival within macrophages. The best characterized of these PhoP-activated genes (pag) is pagC, which encodes a 188-amino-acid envelope protein (W. S. Pulkkinen and S. I. Miller, J. Bacteriol. 173:86-93, 1991). We here report the identification of four genes (pagD, envE, msgA, and envF) located 5' to pagC. Each gene is transcribed from its own promoter, two of which (msgA and pagD) were defined by primer extension analysis. Three of these genes (pagD, envE, and envF) are predicted to encode envelope proteins. The pagD gene is transcribed in a direction opposite from that of and adjacent to pagC and is positively regulated by PhoP/PhoQ. Transposon insertions within pagD and msgA attenuate bacterial virulence and survival within macrophages; however, deletion of pagD has no effect on virulence. The product of the envF gene is predicted to be a lipoprotein on the basis of the presence of a consensus lipid attachment site. The low G + C content of these genes and the homology of msgA to Shigella plasmid DNA suggest that this region may have been acquired by horizontal transmission.

Salmonella stimulate macrophage macropinocytosis and persist within spacious phagosomes

Light microscopic studies of phagocytosis showed that Salmonella typhimurium entered mouse macrophages enclosed in spacious phagosomes (SP). Viewed by time-lapse video microscopy, bone marrow-derived macrophages exposed to S. typhimurium displayed generalized plasma membrane ruffling and macropinocytosis. Phagosomes containing Salmonella were morphologically indistinguishable from macropinosomes. SP formation was observed after several methods of bacterial opsonization, although bacteria opsonized with specific IgG appeared initially in small phagosomes that later enlarged. In contrast to macropinosomes induced by growth factors, which shrink completely within 15 min, SP persisted in the cytoplasm, enlarging often by fusion with macropinosomes or other SP. A Salmonella strain containing a constitutive mutation in the phoP virulence regulatory locus (PhoPc) induced significantly fewer SP. Similar to Yersinia enterocolitica, PhoPc bacteria entered macrophages in close-fitting phagosomes, consistent with that expected for conventional receptor-mediated phagocytosis. These results suggest that formation of SP contributes to Salmonella survival and virulence.