Antibiotic resistance in Gram-negative bacteria affecting children from León, Nicaragua

Annual child mortality has declined in the world from 12.5 million in 1990 to 8.8 million in 2008. Yet, infectious diseases are still the major cause of death in this group (6.97 million); with diarrhoea responsible for the death of 1.3 million and neonatal septicaemia for 0.5 million. On the positive side, Latin America/Caribbean is among the regions with the highest progress in reduction of child mortality.

In Nicaragua, nearly 4000 children under 5 years of age died in 2008, with diarrhoea as the cause of death for 343 children and neonatal sepsis for the death of 62 children. A key problem in the management of diseases such as diarrhoea or septicaemia has been the emergence of antibiotic resistant Gram-negative bacteria. The treatment options for Gram-negative infections affecting children are scarce or with probable toxics effects as for the neonates. Thus, the global burden of antimicrobial resistance requires appropriate interventions. Local surveillance to identify prevalent pathogens and bacterial resistance patterns is necessary for selecting optimal treatment regimens with the aim of a positive outcome in the patient. Furthermore, the evidence that this surveillance can provide with the environmental water is crucial in order to create risk management strategies for these settings. However, in Nicaragua this information is still lacking. Thus the studies presented in this thesis focused in the determination of the prevalence of antibiotic resistant Gram-negative bacteria in children and environmental water. The results from the first study are: 74% (34/46) of the bacteria related to neonates with septicaemia were Gram-negative bacteria, mainly Klebsiella pneumoniae, Serratia marcescens and Serratia liquefaciens. Interestingly, these pathogens were also isolated in the neonatal intensive care unit (NICU) environment. The K. pneumoniae showed clonal similarity among the isolates affecting neonates and those from the NICU s environment.

High levels of antibiotic resistance were found in those Gram-negative, e.g. more than 85% of K. pneumoniae strains from neonates with septicaemia, and the environment were resistant to ceftazidime, ceftriaxone, and gentamicin. Furthermore, a high prevalence of TEM-1, SVH-11/12 and CTX-M-15-producing Gram-negative bacteria from the neonates with septicaemia and the NICU s environment was found. Thus, implementation of infection control practices, and appropriate empirical therapy should also be considered to reduce the prevalence as well as the dissemination of these organisms in this area. The results from the second study are: 47% (296 of 727) of the E. coli isolates analyzed were resistant to ampicillin and trimethoprim-sulfamethoxazole. Enteroaggregative E. coli showed higher resistance levels to most of the tested antibiotics when compared to other E. coli categories.

In general, the antibiotic resistance level in E. coli, from children with/without diarrhoea, have not yet reached the high levels of resistance to the most common antibiotics used for diarrhoea treatment as in other countries, yet CTX-M-5 or CTX-M-15 production was detected in some multi-antibiotic resistant diarrhoeagenic and non-diarrhoeagenic E. coli isolates. This suggests the emergence of ESBL in the Nicaraguan community and may indicate future treatments complications. The results from the third study are: Among all of the E. coli isolates included in this study, those from the hospital sewage water showed higher antibiotic resistance levels to ampicillin (100%), nalidixic acid (70%), ciprofloxacin (69%), chloramphenicol (69%) and trimethoprimsulfamethoxazole (100%) compared to the other E. coli isolates. Among the well water samples which represent the contribution of the community in the input of antibiotic resistance bacteria to the aquatic environment, E. coli isolates from well water sample P55 were fully resistant to the tested antibiotics which indicated a high contribution to the spread of multi-antibiotic resistant bacteria. Our results suggest that multi-resistant CTX-M-9 and CTX-M-15-producing E. coli were widely spread in hospital sewage water and some community water samples.

List of scientific papers

I. Amaya E, Caceres M, Fang H, Ramirez AT, Palmgren AC, Nord CE, Weintraub A. (2009). "Extended-spectrum beta-lactamase-producing Klebsiella pneumoniae in a neonatal intensive care unit in León, Nicaragua." International Journal of Antimicrobial Agents 33: 386-387
https://pubmed.ncbi.nlm.nih.gov/19097869

II. Amaya E, Caceres M, Fanc H, Torres Ramirez A, Palmgren AC, Nord CE, Weintraub A. (2010). "Antibiotic resistance patterns in gram-negative and gram-positive bacteria causing septicemia in newborns in León, Nicaragua: correlation with environmental samples." Journal of Chemotherapy 22: 25-29
https://pubmed.ncbi.nlm.nih.gov/20227989

III. Amaya E, Reyes D, Vilchez S, Paniagua M, Möllby R, Nord CE, Weintraub A (2010). "Antibiotic resistance patterns of intestinal Escherichia coli isolates from Nicaraguan children." Journal of Medical Microbiology (Submitted)

IV. Amaya E, Reyes D, Paniagua M, Calderón S, Colque P, Kühn I, Möllby R, Nord CE, Weintraub A. (2010). "Antibiotic resistance patterns of Escherichia coli isolates from different aquatic environmental sources in León, Nicaragua." (Manuscript)