Evaluation of the efficacy of intramuscular versus intramammary treatment of subclinical Streptococcus agalactiae mastitis in dairy cows in Colombia.

A randomized controlled trial was performed in 17 Colombian dairy herds to determine the cure risk among cows subclinically infected with Streptococcus agalactiae exposed to 2 antibiotic therapies. Composite milk samples were collected before milking at the onset of the trial (pretreatment) and 2 subsequent times over a period of approximately 63 d. The intramammary application (IMM) of ampicillin-cloxacillin was compared with the intramuscular application (IM) of penethamate hydriodide, and cure risks after an initial and retreatment application were assessed. Cure risk after the initial treatment was higher (82.4%) for the IMM treatment than for IM therapy (65.8%). However, no difference was observed in the cure risk of refractory cases after retreatment (IMM=52.6% vs. IM=51.2%). The cumulative cure risk (both initial and retreatment) was 90.4 and 82.9% for the IMM and IM products, respectively. A 2-level random effects logistic model that controlled for pretreatment cow-level somatic cell count, indicated that IM treatment (odds ratio=0.37) had a lower cure risk than IMM and a tendency for a lower cure risk with increasing baseline somatic cell count. Our findings suggest that both products and administration routes can reduce the prevalence of S. agalactiae in affected herds, but the IMM product had a better efficacy in curing the infection. In addition to the treatment protocol, the cow somatic cell count should be considered when making management decisions for cows infected with S. agalactiae.

Application of capillary electrophoresis to the simultaneous determination and stability study of four extensively used penicillin derivatives

The applicability of capillary electrophoresis for the analysis of four extensively used penicillin derivatives (benzylpenicillin, ampicillin, amoxicillin, oxacilllin) has been studied. Because of structural similarities, the electrophoretic behavior of these derivatives is very similar; consequently an efficient separation using the conventional capillary zone electrophoresis is hard to be achieved. Their simultaneous separation was solved by using micellar electrokinetic capillary chromatography, the separation being based on the differential partition of the analytes between the micellar and aqueous phase. Using a buffer solution containing 25 mM sodium tetraborate and 100 mM sodium dodecyl sulfate as surfactant, at a pH of 9.3, applying a voltage of + 25 kV at a temperature of 25 °C, we achieved the simultaneous separation of the studied penicillin derivatives in less then 5 minutes. The separation conditions were optimized and the analytical performance of the method was evaluated in terms of precision, linearity, limit of detection, and quantification. Also, a simple capillary zone electrophoresis method was applied to study the stability of the studied penicillin derivatives in water at different temperatures, using ciprofloxacin hydrochloride as internal standard. It was observed that the extent of the hydrolysis of penicillins in water is highly dependent on the time and also temperature.

Estudou-se a aplicabilidade de electroforese capilar para a análise de quatro derivados de penicilina (benzilpenicilina, ampicilina, amoxicilina, oxacilina) amplamente utilizados. Em razão das semelhanças estruturais, o comportamento electroforético destes derivados é muito semelhante e, por conseguinte, a separação eficaz utilizando a electroforese capilar de zona convencional é difícil de ser efetuada. A separação simultânea foi realizada por cromatografia capilar electrocinética micelar, que se baseia na partição diferencial entre os analitos na fase micelar e aquosa. Utilizando-se solução tampão contendo 25 mM de tetraborato de sódio e 100 mM de dodecil sulfato de sódio, como agente tensioativo, com pH de 9,3, voltagem de +25 kV, à temperatura de 25 °C, obteve-se a separação simultânea das penicilinas estudadas em menos de 5 minutos. As condições de separação foram otimizadas e o desempenho do método analítico foi avaliado em termos de precisão, linearidade, limite de detecção e de quantificação. Além disso, aplicou-se método de electroforese capilar de zona simples para estudar a estabilidade de penicilinas em água a diferentes temperaturas, utilizando cloridrato de ciprofloxacino como padrão interno. Estabeleceu-se que o grau de hidrólise de penicilinas em água é altamente dependente do tempo e também da temperatura.

Standardized symptomatic treatment versus penicillin as initial therapy for streptococcal pharyngitis.

A multicenter, double-blind, randomized, placebo-controlled trial was conducted to determine whether the addition of penicillin was superior to patient education and anti-inflammatory drug therapy for relief of the acute discomforts of pharyngitis caused by group A beta-hemolytic streptococcus (GABHS). One hundred seventy-eight patients, aged 4 to 29 years, received appropriate symptomatic therapy, including specific doses of aspirin or acetaminophen, plus penicillin (91 patients) or placebo (87) for the initial 48 hours of illness. All had 24-hour office and 48-hour telephone reevaluations. In 123 patients (57 with clinically severe pharyngitis), throat cultures yielded GABHS. Penicillin provided a margin of 20% improvement over anti-inflammatory therapy for the complaint of sore throat only after 48 hours of treatment (for the 123 patients with GABHS, p = 0.01; for the 57 with both severe pharyngitis and GABHS, p = 0.05). No significant improvement was noted for fever, malaise, odynophagia, exudate, adenitis, or pharyngitis. The failure of penicillin to provide much additional benefit makes its routine early prescription specifically for symptomatic relief questionable.

Serum concentrations of penicillin after intramuscular administration of procaine, benzyl, and benethamine penicillin in children with pneumonia.

Serum concentrations of penicillin were measured in 37 children with pneumonia. The mean serum concentration of penicillin was greater than 1.0 microgram/mL for 11 hours after intramuscular administration of 48,000 U/kg benethamine penicillin compound (nine children), for 26 hours after 48,000 U/kg aqueous procaine penicillin (10 children), and for 40 hours after 79,000 U/kg aqueous procaine penicillin (seven children). After intramuscular administration of 35,000 U/kg benzyl penicillin in 11 children, the serum concentration was 13.3 +/- 7.4 micrograms/mL (mean +/- SD) 30 minutes after the injection, and 4.9 +/- 3.2 micrograms/mL after 3 hours. Our findings lend support to the World Health Organization recommendation that children with mild pneumonia in developing countries be given daily intramuscular injections of 50,000 U/kg aqueous procaine penicillin.