ESβL and MβL Production in Gram-Negative Bacteria Isolated From HIV Seropositive Individuals

Extended-spectrum β-lactamase (ESβL) or metallo-β-lactamase (MβL) production by gram-negative bacteria in immunocompromised patients poses a serious therapeutic challenge for infection control and is associated with infections with a higher morbidity/mortality, especially in developing countries. This study aimed to phenotypically evaluate the production of ESβL as well as MβL in 75 gram-negative bacterial isolates from clinical samples of the human immunodeficiency virus (HIV) positive individuals.

Bacterial identification was by chromogenic media, analytical profile index 20 E, and 20 NE kits, and ESβL production was tested by double-disc synergy test (DDST) and combination disc method, while MβL production was screened with imipenem ethylene diamine tetra-acetic acid (EDTA) combined disc and EDTA-disc potentiation with ceftazidime.

Altogether, 57 isolates (76.0%) produced ESβL either with DDST (6), combination disc method (49), or both (2). DDST detected the ESβL enzyme in 10.7% of the tested isolates which were all Pseudomonas aeruginosa. None of the bacterial isolates revealed MβL production with the imipenem/imipenem-EDTA method, whereas 26.7% of tested isolates produced MβL with EDTA-disc potentiation using ceftazidime out of which 65.0% were P. aeruginosa. Moreover, ESβL/MβL co-production was evident in 22.7% of the tested bacterial isolates with P. aeruginosa constituting 64.7%.

ESβL and MβL co-production among the studied isolates indicates a heightened resistance to β-lactam antibiotics, suggesting grave health consequences, especially in immunocompromised individuals with already limiting therapeutic options in the region. The study revealed higher ESβL production compared to MβL production in isolates, with the predominating producing specie being P. aeruginosa, and higher ESβL and MβL detection by the combination disc method and EDTA-disc potentiation using ceftazidime, respectively.