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Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060
EISSN: 1678-8060
Vol. 94, No. 6, 1999, pp. 795-802
Bioline Code: oc99232
Full paper language: English
Document type: Research Article
Document available free of charge

Memórias do Instituto Oswaldo Cruz, Vol. 94, No. 6, 1999, pp. 795-802

 en Evidences of Gentamicin Resistance Amplification in Klebsiella pneumoniae Isolated from Faeces of Hospitalized Newborns
Barros, Julio César de Siqueira; Pinheiro, Sebastião Ronaldo; Bozza, Marcelo; Gueiros-Filho, Frederico José; Bello, Alexandre Ribeiro; Lopes, Ulisses Gazos & Pereira, José Augusto Adler


The intestinal microbiota, a barrier to the establishment of pathogenic bacteria, is also an important reservoir of opportunistic pathogens. It plays a key role in the process of resistance-genes dissemination, commonly carried by specialized genetic elements, like plasmids, phages, and conjugative transposons.

We obtained from strains of enterobacteria, isolated from faeces of newborns in a university hospital nursery, indication of phenothypical gentamicin resistance amplification (frequencies of 10-3 to 10-5, compatible with transposition frequencies). Southern blotting assays showed strong hybridization signals for both plasmidial and chromossomal regions in DNA extracted from variants selected at high gentamicin concentrations, using as a probe a labeled cloned insert containing aminoglycoside modifying enzyme (AME) gene sequence originated from a plasmid of a Klebsiella pneumoniae strain previously isolated in the same hospital. Further, we found indications of inactivation to other resistance genes in variants selected under similar conditions, as well as, indications of co-amplification of other AME markers (amikacin).

Since the intestinal environment is a scenario of selective processes due to the therapeutic and prophylactic use of antimicrobial agents, the processes of amplification of low level antimicrobial resistance (not usually detected or sought by common methods used for antibiotic resistance surveillance) might compromise the effectiveness of antibiotic chemotherapy.

resistance amplification - aminoglycosides modifying enzymes - Klebsiella pneumoniae

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