ABSTRACT
La susceptibilidad reducida a vancomicina ha sido encontrada en estudios previos de aislamientos clínicos de pacientes con evolución médica inadecuada. Presentamos un caso con aislamiento de una cepa de staphylococcus haemolyticus con susceptibilidad reducida a vancomicina obtenida de un paciente recién nacido con neuroinfección a los 17 días de vida con evolución clínica adecuada después de 21 días de tratamiento. Se realizó análisis de susceptibilidad intermedia a 44 cepas de staphylococcus coagulasa negativa mediante las técnicas descritas por Wong (método de disco en agar adicionado con sal de vancomicina en concentración ≥ de 8 μg/ml en el que se demuestra satelitismo alrededor de un disco de aztreonam). La cepa fue susceptible a vancomicina al analizar la sensibilidad por un método automatizado (Sistema MicroScanR, Dade Behring). Este es el primer informe de heteroresistencia en México y una alerta temprana de la posible emergencia de staphylococcus con algún tipo de resistencia a vancomicina.
Reduced susceptibility to vancomycin has been reported among clinical isolates of Staphylococcus in previous studies. The present study describes a heteroresistant Staphylococci strain from the cerebrospinal fluid of a 17 day-old premature male infant with neonatal meningitis. Screening was done for 44 strains of coagulase-negative staphylococci using Wong 's techniques (Disk-agar method with vancomycin-salt agar to demonstrate satellitism around an aztreonam disk). Strains were susceptible to vancomycin as disclosed by an automated antimicrobial susceptibly test (Microscan System Dade Behring). This is the first report of heterogeneous resistance to vancomycin in Mexico and an early warning for the possible emergence of vancomycin resistance among coagulase-negative staphylococcus in our country.
Subject(s)
Humans , Male , Infant, Newborn , Anti-Bacterial Agents/pharmacology , Staphylococcus haemolyticus/drug effects , Vancomycin Resistance , Vancomycin/pharmacology , Mexico , Microbial Sensitivity Tests , Staphylococcus haemolyticus/isolation & purificationABSTRACT
Background. Guttate psoriasis is associated with infections by Streptococcus pyogenes and cross-reaction between skin and streptococcal antigens have been reported, suggesting an autoimmune component in the disease. Methods. In this work, the authors looked for antibodies against S. pyogenes M-5 antigens by immunoblot in 52 sera of psoriasis patients and in 52 sera of normal individuals. Histological and immunohistochemical analysis in skin biopsies from lesions of another group of 16 clinically diagnosed guttate psoriasis patients and four healthy controls were also carried out. Results. All guttate psoariasis patients studied (11) had IgG antibodies that intensively recognized three different proteins of 70,60 and 14 kDa, as compared to sera from patients with other forms of psoriasis or from healthy controls. The diagnosis of psoariasis was confirmed in 14 of the patients by hematoxylin-eosin staining. Of the other two patients, one was diagnosed as parapsoriasis and the other as liquen. By indirect immunofluorescence (IFI), all 14 psoriatic patients had autoantibodies against their own lesional skin that did not recognized normal skin from control subjects or from the two non-psoriatic patients. The parapsoriatic and the liquen patients did not have autoantibodies. A rabbit immune serum against S. pyogenes antigens reacted with lesional skin from the 14 guttate psoriatic patients, but not with normal skin from controls or with lesional skin from the 2 non-psoriatic patients. Conclusions. The recognition by immunoblot of streptococcal antigens by serum of guttate psoriasis patients, the presence of autoantibodies against their own skin, and recognition of the same skin antigens by anti-streptococcal rabbit antibodies confirm the participation of the immune system and of streptococcal infection in guttate psoriasis