Quorum Sensing Interfering Strategies and Their Implications in the Management of Biofilm-Associated Bacterial Infections

Abstract The bacterial species employ various types of molecular communication systems recognized as quorum sensing for the synchronization of differential gene expression to regulate virulence traits and biofilm formation. A variety of quorum sensing inhibitors; molecules that interfere with quorum sensing among bacteria have been examined which can block the action of autoinducers. Moreover, the studies have scrutinized various enzymes for their quorum quenching activity resulting in the degradation of signaling molecules or blocking of gene expression. So far, the studies have found that these approaches are not only capable to reduce the pathogenicity and biofilm formation but also resulted in increased bacterial susceptibility to antibiotics and bacteriophages. The effectiveness of these strategies has been validated in different animal models and it seems that these practices will be transformed in near future to develop the medical devices including catheters, implants, and dressings for the prevention of bacterial infections. Although many of these approaches are still in the research stage, the increasing library of quorum quenching molecules and enzymes will open innovative perspectives for the development of antibacterial approaches which will extend the therapeutic arsenal against the pathogenic bacterial species.

Cross-sectional epidemiological investigations of Giardia lamblia in children in Pakistan

ABSTRACT BACKGROUND: The prevalence of Giardia lamblia in Pakistani children is currently unknown. The aim here was to evaluate the prevalence and risk factors of Giardia lamblia in children exhibiting diarrhea. DESIGN AND SETTING: Cross-sectional study at different district healthcare hospitals in Pakistan. METHODS: A total of 800 samples were collected from children aged 0-10 years. Information regarding personal data, demographic data and supposed risk factors was collected through a structured questionnaire. Giardia lamblia was detected through direct microscopy and antigens through the enzyme-linked immunosorbent assay (ELISA). RESULTS: The prevalence of Giardia lamblia was 2.75% through direct microscopy and inflated to 9.5% through ELISA. The demographic factors positively associated with occurrences of giardiasis were age (P = 0.035; odds ratio, OR = 1.96; 95% confidence interval, CI = 1.094-3.533), mother's educational level (P = 0.031; OR = 2.67; 95% CI = 1.186-6.045) and father's educational level (P = 0.004; OR = 3.56; 95% CI = 1.612-7.899). Similarly, among the supposed risk factors, rural residency (P = 0.032; OR = 1.76; 95% CI = 1.098- 2.851), absence of proper sewerage system (P = 0.000; OR = 6.60; 95% CI = 4.029-10.841) and unavailability of safe drinking water (P = 0.000; OR = 4.08; 95% CI = 2.207-7.547) were the factors strongly connected with giardiasis. Abdominal discomfort was a prominent clinical sign with 46% frequency. CONCLUSION: Various risk factors were associated with occurrences of Giardia, thus emphasizing the importance of parents' education, safe drinking water and proper sewerage systems for Pakistani children's health.

Antimicrobial susceptibility of acinetobacter clinical isolates and emerging antibiogram trends for nosocomial infection management

Abstract: Introduction: The drug resistant Acinetobacter strains are important causes of nosocomial infections that are difficult to control and treat. This study aimed to determine the antimicrobial susceptibility patterns of Acinetobacter strains isolated from different clinical specimens obtained from patients belonging to different age groups. METHODS: In total, 716 non-duplicate Acinetobacter isolates were collected from the infected patients admitted to tertiary-care hospitals at Lahore, Pakistan, over a period of 28 months. The Acinetobacter isolates were identified using API 20E, and antimicrobial susceptibility testing was performed and interpreted according to Clinical and Laboratory Standards Institute (CLSI) guidelines. RESULTS: The isolation rate of Acinetobacter was high from the respiratory specimens, followed by wound samples. Antibiotic susceptibility analyses of the isolates revealed that the resistance to cefotaxime and ceftazidime was the most common, in 710 (99.2%) specimens each, followed by the resistance to gentamicin in 670 (93.6%) isolates, and to imipenem in 651 (90.9%) isolates. However, almost all isolates were susceptible to tigecycline, colistin, and polymyxin B. CONCLUSIONS: The present study showed the alarming trends of resistance of Acinetobacter strains isolated from clinical specimens to the various classes of antimicrobials. The improvement of microbiological techniques for earlier and more accurate identification of bacteria is necessary for the selection of appropriate treatments.

Penicillin production by wild isolates of Penicillium chrysogenum in Pakistan

The present study was aimed at exploring the native wild isolates of Penicillium chrysogenum series in terms of their penicillin production potential. Apart from the standard medium, the efforts were made to utilize suitable agro-industrial wastes for the maximum yield of penicillin. Two series of P. chrysogenum were isolated from local sources and named as P. chrysogenum series UAF R1 and P. chrysogenum series UAF R2. The native series were found to possess better penicillin production potential than the already reported series of P. chrysogenum. However, P. chrysogenum series UAF R1 was found to be the best candidate for high yield of penicillin starting at 100 hour as compared to P. chrysogenum series UAF R2 which produced the highest yield of penicillin at 150 hours for a shorter period of time. Addition of Corn Steep Liquor (CSL) to the fermentation medium resulted in the production of 1.20g/L penicillin by P. chrysogenum series UAF R1 and P. chrysogenum series UAF R2. The fermentation medium in which Sugar Cane Bagasse (SCB) was replaced with CSL resulted in the highest yield of penicillin (1.92g/L) by both native series of P. chrysogenum. The penicillin production was increased by 62.5% in medium with SCB as compared to that with CSL. The penicillin yield of medium containing lactose and phenyl acetate was higher than that of control medium. Overall results revealed that P. chrysogenum series UAF R1 and P. chrysogenum series UAF R2 may be recommended for better yield of natural penicillin and this efficiency may be further enhanced by utilizing SCB as substrate in the growth medium.

Ethambutol resistance of indigenous Mycobacterium tuberculosis isolated from human patients

The present study was conducted to find out the ethambutol resistance pattern of indigenous isolates of Mycobacterium tuberculosis from Tuberculosis diagnosed human patients. A total of 172 specimens were collected from six different sources and comprised of 84.9 percent sputum, 10.5 percent pus and 4.7 percent bronchial washings. There were 70.9 percent males and 29.1 percent females with 84.30 percent pulmonary and 15.69 percent extra-pulmonary tuberculosis. The Mycobacterium tuberculosis isolates collected from primary culture were further studied to determine their pattern and level of resistance. The inoculums were prepared using 0.5 Mac Farland turbidity standards. Five different concentration of ethambutol were used in Lowenstein Jensen (LJ) medium i.e. 2μg/ml, 4μg/ml, 6μg/ml, 8μg/ml and 10μg/ml for sensitivity testing. Data showed 10 (5.8 percent) resistant and 162 (94.2 percent) sensitive Mycobacterium tuberculosis out of total 172 clinical isolates. The growth was not inhibited at 1st (2μg/ml) and 2nd (4μg/ml) drug levels, while growth of 50 percent isolates inhibited at 3rd level (6μg/ml), 30 percent inhibited at 4th level (8μg/ml) and 20 percent at 5th level (10μg/ml). The last three levels are above the therapeutic index and not recommended in actual clinical practice. It is thus conceivable to explore some other more effective chemotherapeutic agents, modify combinations or find more effective procedures to stop morbidity and mortality due to ethambutol resistant Mycobacterium tuberculosis.