Trends in antimicrobial resistance patterns of Group A streptococci, molecular basis and implications

Background: Group A streptococcus (GAS) causes a wide variety of diseases ranging from mild skin and soft-tissue infections to severe, life-threatening conditions. A fluctuating trend has been observed in the antibiotic resistance pattern from different parts of the world. The present study was undertaken to determine the prevalence of antibiotic resistance among GAS isolates and the underlying genetic mechanisms. Materials and Methods: Two hundred and six GAS isolates were characterised by antimicrobial susceptibility pattern, macrolide resistance phenotype (double-disc test) and resistance determinants by multiplex polymerase chain reaction. Results: All the isolates were susceptible to penicillin, vancomycin and linezolid. Erythromycin resistance was found in 53% of isolates with inducible macrolide, lincosamide and streptogramin B the predominant phenotype (63%) with ermB the major genetic determinant. Clindamycin resistance was observed in 33% of isolates with all being inducible resistant. Tetracycline resistance was found in 58% of isolates with tetM as the major genetic determinant (97%). Erythromycin and tetracycline co-resistance was found in 39% of tested GAS isolates. Conclusion: The erythromycin and tetracycline resistance in GAS continues to exist at high levels and may be attributed to the over-prescription and use of these antibiotics. Our findings indicate that the use of these antibiotics especially macrolides as empiric therapy in penicillin-allergic patients may not be appropriate.

Studies on the changes in lipid peroxidation and antioxidants in drought stress induced cowpea (Vigna unguiculata L.) varieties.

Cowpea (Vigna unguiculata L.) is one of the major vegetable crops cultivated in tropical conditions. Two varieties of cowpea, i.e., Vigna unguiculata L.cv Kanakamony and cv Pusakomal were selected for the present study. The changes in lipid peroxidation, ascorbic acid content and activities of enzymatic antioxidants associated with drought stress were determined. A high level of lipid peroxidation was observed in test plants subjected to water stress. The Pusakomal leaves with severe stress showed 2.7 fold increase in TBARS compared to control and 1.2 fold to that of Kanakamony The drought tolerant variety showed significant increase in the activities of peroxidase and catalase on exposure to drought stress. Kanakamony leaves in severe stress possess 1.09 times increase in peroxidase and 1.8 times increase in catalase activity than Pusakomal. The concentration of ascorbic acid in test plants depleted with increased drought stress in both varieties. While the leaves of tolerant variety in severe stress showed 1.13 times higher ascorbic acid content than Pusakomal. Among the two varieties, Kanakamony possess the best antioxidant system to tolerate drought stress. This could limit cellular damage caused by active oxygen species, during waterdeficit. The variety Pusakomal was relatively poor in these adaptations.

Reno-protective effect of N-acetyl cysteine in patients with impaired renal function undergoing coronary angiography and interventions.

BACKGROUND: The increasingly frequent use of contrast enhanced imaging for diagnosis or interventions in patients with CAD has generated concern about avoidance of contrast induced nephropathy (CIN). Reactive oxygen species have been shown to cause CIN. OBJECTIVES: Angiographic contrasts worsen the renal function in patients with renal failure. We studied the reno-protective action of the antioxidant N-Acetyl cysteine (NAC) in patients undergoing coronary procedures. METHODS: Retrospective analysis of 51 patients with elevated serum creatinine levels (> or = 15mg%) was done, 24 of whom received NAC prior to the procedure(NAC group) and 27 who did not (Non NAC group). NAC was administered in a dose of 400 mg twice daily for four doses starting on the day prior to the procedure. Both groups of patients were hydrated with 0.45% saline at 1 ml/kg/hr for 12 hours prior to and 12 hours following the procedure. Both groups were comparable with regard to age, sex, coronary risk profile, myocardial infarction history, left ventricular function and the drugs received. Serum urea and creatinine were measured on the day prior to and the day following the angiographic procedure. RESULTS: Nine out of 51 patients developed more than 0.5mg% rise in serum creatinine level; 1 in the NAC group and 8 in the non NAC group (p<0.05), 24 hours after injection of the contrast medium. In the NAC group mean serum creatinine level decreased from 1.94 +/- 0.56 to 1.67 +/- 0.56 and blood urea from 47.58 +/- 20 to 41.58 +/- 15.1. In the non NAC group serum creatinine increased from 1.75 +/- 0.31 to 1.98 +/- 0.56 and blood urea from 44.96 +/- 15.5 to 52.85 +/- 20.1 (p<0.05). This corresponds to an increase in creatinine clearance from 30ml/min to 35.92ml/min in the NAC group and a decrease from 34.42ml/min to 29.87ml/min in the non NAC group. There was no significant difference in the levels of sodium and potassium before and after the procedure in both the groups. CONCLUSION: We conclude that prophylactit administration of N-Acetyl Cysteine along with hydration diminishes the incidence of deterioration of renal function induced by contrast agents in patients with renal insufficiency during coronary angiographic procedures.

Diagnosing enteric fever: a reappraisal.

The diagnostic value of 19 clinical and laboratory events was assessed in 150 enteric fever cases. A logistic regression analysis revealed only 8 predicitive variables for the presence or absence of enteric fever. These were, in order of importance, the white blood cell count, the S. typhi H agglutinin titre, body temperature, the S. typhi O agglutinin titre, the S. paratyphi A H agglutinin titre, the S. paratyphi B H agglutinin titre, age and the fever pattern. This study showed that objective variables like the Widal titres were useful in predicting enteric fever, whilst symptoms such as abdominal pain were unhelpful. Use of all 8 variables to calculate the probability of enteric fever might provide an accurate method of diagnosing or confirming enteric fever when culture results are unavailable or negative.