Members of the family Enterobacteriaceae are responsible for a variety of nosocomial infections, treatment of which is limited due to their increasing resistance to antibiotics. Some bacterial genes encoding antibiotic resistance comprise the major part of gene cassettes, most of which are associated with integrons. In this work, the carriage of class 1, 2 and 3 integrons was investigated in 191 Enterobacteriaceae isolates from clinical specimens of hospitalized patients. Class 1 integrons were found to be the most common, whereas no class 3 integrons were detected. The variable regions of 13 class 1 integrons were characterized and four types were found. Type 1 harbours only ant(3")I, type 2 harbours ant(2")I and ant(3")I, type 3 harbours aac(6')Ib and ant(3")I and type 4 lacks inserted gene cassettes.

Staphylococcus aureus isolates resistant to several antimicrobials have been gradually emerged since the beginning of the antibiotic era. Consequently, the first isolation of methicillin-resistant S. aureus occurred in 1960, which was described a few years later in Chile. Currently, S. aureus resistant to antistaphylococcal penicillins is endemic in Chilean hospitals and worldwide, being responsible for a high burden of morbidity and mortality. This resistance is mediated by the expression of a new transpeptidase, named PBP2a or PBP2', which possesses lower affinity for the β-lactam antibiotics, allowing the synthesis of peptidoglycan even in presence of these antimicrobial agents. This new enzyme is encoded by the mecA gene, itself embedded in a chromosomal cassette displaying a genomic island structure, of which there are several types and subtypes. Methicillin resistance is mainly regulated by an induction mechanism activated in the presence of β-lactams, through a membrane receptor and a repressor of the gene expression. Although mec-independent methicillin resistance mechanisms have been described, they are clearly infrequent.

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Monoarticular tuberculosis of the wrist is a rare presentation of primary tuberculosis, being more common skeletal forms involving the spine. Extraspinal tuberculous osteomyelitis is rare and comprises only 2 to 3% of all cases of osteoarticular Mycobacterium tuberculosis infections. We present a case of a 49 years old female patient, who worked as an hospital cleaning employed without other comorbidity. After a low energy injury of the wrist she suffered pain syndrome diagnosticated as a flexor tendinopathy, managed with nonsteroidal antiinflammatory drugs and physical therapy. Eight months later patient evolves with chronic pain in range of motion of right wrist joint, leading to a complete radiological, surgical biopsy and cultures. Histology, and molecular biology confirmed the wrist joint tuberculosis diagnosis. Pharmacological treatment and physical therapy were initiated with appropriated response.

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