Antimycobacterial compound of chitosan and ethambutol: ultrastructural biological evaluation in vitro against Mycobacterium tuberculosis

Chitosan (CS) is a promising biopolymer and has been tested as a complement to the action and compensation of toxicity presented by anti-tuberculosis drugs. The present work studied the adjuvant effect of CS with the drug ethambutol (EMB) as a compound (CS-EMB), to explore its antimicrobial and cytotoxic activity, using transmission electron microscopy (TEM), to examine ultracellular changes that represent possible antimycobacterial action of CS on Mycobacterium tuberculosis (Mtb). Antimycobacterial activities were tested against reference strains Mtb ATCC® H37Rv and multidrug resistant (MDR). In vitro cytotoxicity tests were performed on Raw 264.7. For the studied compounds, morphological, ultrastructural, and physical-chemical analyses were performed. Drug-polymer interactions that occur through the H bridges were confirmed by physical-chemical analyses. The CS-EMB compound is stable at pHs of 6.5-7.5, allowing its release at physiological pH. The antibacterial activity (minimum inhibitory concentration) of the CS-EMB compound was 50% greater than that of the EMB in the H37Rv and MDR strains and the ultrastructural changes in the bacilli observed by TEM proved that the CS-EMB compound has a bactericidal action, allowing it to break down the Mtb cell wall. The cytotoxicity of CS-EMB was higher than that of isolated EMB, IC50 279, and 176 μg/mL, respectively. It is concluded that CS-EMB forms a promising composite against strains Mtb H37Rv and multidrug resistant (MDR-TB).Key points• Our study will be the first to observe ultrastructurally the effects of the CS-EMB compound on Mtb cells.• CS-EMB antimicrobial activity in a multidrug-resistant clinical strain.• The CS-EMB compound has promising potential for the development of a new drug to fight tuberculosis.

Clinical impact of transesophageal echocardiography in patients with stroke without clinical evidence of cardiovascular sources of emboli

OBJECTIVE

The purpose of this study is to evaluate the impact of transeophageal echocardiography on management of patients at low-risk for cardiogenic embolism to prevent new potential cardiovascular sources of emboli.

METHODS

We studied 69 patients with ischemic stroke at low-risk for cardiogenic embolism. Transeophageal echocardiography was performed to access: left atrium enlargement; communication or aneurysm of the interatrial septum; patent foramen ovale; spontaneous echo contrast or intracavitary thrombi; the presence of intraaortic atherosclerotic plaques or thrombi; significant valvar morphologic alteration or dysfunction; left ventricle enlargement, hypertrophy, or contractile abnormality. Transesophageal echocardiography altered clinical management, and we adopted anticoagulant therapy or another procedure apart from the use of acetylsalicylic acid.

RESULTS

Transeophageal echocardiography detected at least one abnormality in 40 cases (58%). Clinical conduct was adjusted after the performance of transesophageal echocardiography in 11 patients (15.9%); anticoagulation was added in 10 cases and surgical correction in one patient.

CONCLUSION

Transeophageal echocardiography was a very useful tool in the secondary prevention for stroke in patients at low risk for cardiogenic embolism.

[Recurrent abdominal pain at the Pediatric Gastroenterology Outpatient Clinic]

OBJECTIVE

To analyze the features of pediatric patients with recurrent abdominal pain, identify the main ethiologic diagnoses and their clinical and laboratorial differences.

PATIENTS AND METHODS

We studied the medical records from 167 children attended at a pediatric gastroenterology outpatient clinic. After analysis of the entire sample, the patients were divided in groups according to their diagnosis. Those patients with more than one diagnosis were arranged into a subgroup named multiple diagnosis. Statistical analysis was performed with Kruskall-Wallis test for numeric variables and chi-square test for non-numeric variables.

RESULTS

The patients age ranged from 3 to 17 years (median 9), the number of consultations ranged from 1 to 16 (median 2) and the period of attendance ranged from 1 to 37 months (median 4). The pain was mainly periumbilical (35.8%) and crampy-like (76.1%). The main diagnoses found were chronic intestinal constipation (58.6%), intestinal parasitosis (22.8%), and peptic disease (20.4%). In 34 patients (20.3%) we were not able to establish the diagnosis. Among the groups, there was statistically significant difference in age (p=0.00003), number of consultations (p=0.00004), period of attendance (p=0.00001), kind of pain (p=0.0003), intestinal habit (p=0.0002), stool features (p=0.0001), and evolution (p=0.0006).

CONCLUSIONS

The authors conclude that finding organic disease in patients with recurrent abdominal pain is much more common than it was expected. The pediatrician always has to consider the possibility of multifactorial origin for these patients' complaints.