Dithiin diisoimides: Synthesis and their antimicrobial studies.

Sixteen derivatives of dithiin diisoimide 2a-2p have been synthesized and screened for antibacterial and antifungal activity. Compounds 2a-2g and 2i-2p are almost same or more active than gentamicine against Acinetobacter. Whereby compound 2,6-didodecyl-1H,5H-pyrrolo[3',4',5,6][1,4]dithiino[2,3-c]pyrrole-1,3,5,7(2H,6H)-tetrone (2d) having zone of inhibition 20 mm against Acinetobacter is the most potent among all these compounds and can be used as lead compound for the treatment of Acinetobacter infection.

Prevalence and antibiotic resistance profiles of Gram negative bacilli associated with urinary tract infections (UTIs) in Karachi, Pakistan.

The aim of this investigation was to determine the prevalence and antibiotic resistance profiles of Gram negative bacilli (GNB) responsible for urinary tract infections (UTIs). Urine specimens were cultured on Cysteine Lactose Electrolyte Deficient Agar (CLED) medium and pathogenic GNB were identified by conventional biochemical methods and automated profile index (API) system and further subjected to antibiotic sensitivity testing by disk diffusion method. Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii were encountered as most frequent GNB in sequence. Among them E. coli (71%) was the most prevalent GNB. About 77% E. coli isolates of indoor patients and 59% of outdoor patients were found resistant to Cefotaxime. Kleb. pneumoniae were 100% resistant to Ampicillin. Higher resistance in Ps. aeruginosa was noticed in isolates of indoor patients i.e. Ciprofloxacin (76%), Cefoperazone-sulbactam (60%), Ceftazidime (59%), Piperacillin-tazobactam (53%), Imipenem (49%) and Amikacin (39%) in contrast to that of outdoor patients. Slightly lower resistance in Acinetobacter baumannii against Ampicillin (86%), Nitrofurantoin (81%) and Fosfomycin (12%) was witnessed in indoor patients' urine specimens compared to outdoor patients' urine. Polymyxin B, Imipenem, Fosfomycin, Piperacillin-tazobactam, Cefoperazone-sulbactam, Amikacin and Nitrofurantoin were most effective in GNB induced UTIs. This study revealed elevated resistance profiles in GNB against Ampicillin, Amoxicillin-clavulanate, Cefotaxime, Aztreonam, Ciprofloxacin, Nalidixic acid and Trimethoprim/sulfamethoxazole. Emergence of antibiotic resistant GNB was due to the frequent use and misuse of antibiotics in our region.

Industrially relevant cellulase production by indigenous thermophilic Bacillus licheniformis TLW-3 strain: Isolation-molecular identification and enzyme yield optimization.

Cellulases are the third largest single industrial bio-robots. These enzymes are employed in industries like pharmaceutical, textile, food processing, paper recycling and detergent manufacturing. In order to produce broadly diversified cellulases, microbes (both bacteria and fungi) have been exploited. Different ecological niches have already been explored for the isolation of cellulolytic microbes. However, there have been no remarkable reports viz a viz to the hot oven ash (for cellulolytic bacterial flora). In this regard, a Bacillus strainTLW-3 was isolated and selected for CMCase production and optimization. The strain was identified as B. licheniformis TLW-3 through 16S rDNA sequencing that was submitted to Gen Bank with accession numberKY440432. The isolate growth and CMCase production conditions were optimized to get the maximum CMCase yield. The highest growth and maximum CMCase production by B. licheniformis TLW-3 were recorded at pH 7 and 50ºC, after the incubation period of 72 (hour) at 150rpm. Studies on the various nitrogen and carbon sources on CMCase production showed that the medium having 1% peptone, 0.5% yeast extract and 1% CMC can significantly enhance the enzymatic yield as compared to other (studied) sources. EDTA, Tween-20 and Tween-80 acted as inhibitors for the enzyme production. The present study holds the conviction that the (reported) organism could directly be applied to produce industrial thermophilic CMCase.

Industrially important hydrolytic enzyme diversity explored in stove ash bacterial isolates.

Extreme environments merit special attention and significance because of the possible existence of thermophilic microorganisms in such ecological niches. Keeping this in mind indigenous stove ash samples were explored for extremophilic bacteria in term of their biodiversity. Accordingly, this study reports 37 bacterial isolates from the local wood run oven (Tandoor) ash samples. All the isolated strains belong to genus Bacillus on the bases of morpho-cultural and biochemical considerations. The average temperature tolerance profile was >45°C thereby, indicating towards the thermophilic nature of the isolated strains. The Bacillus isolates were screened for 10 different hydrolytic enzymes (cellulase, xylanase, amylase, pectinase, caseinase, keratinase, lipase, esterase, dextranase and ß-galactosidase) by plate screening method using the medium incorporated with specific substrate(s). It was found that keratinase was produced by all the isolates while, 36 (97.2%) isolates showed caseinase and esterase production. Amylase was produced by 35(94.6%) isolates and 34 (91.8%) isolates were able to degrade Tween-80 and xylan as substrate for lipase and xylanase respectively. The enzyme, ß-galactosidase was produced by 31 (89.1%) of the isolates. Cellulase and dextranase were produced by 26 (70.2%) and 22 (59.4%) isolates respectively. None of the isolates could (under the existing conditions) produce pectin-hydrolyzing enzyme. According to the Tukey's post hoc test, significant difference was found between the mean enzyme index of all the (screened) enzymes. Thus, the isolated bacterial strains with diverse hydrolytic potential may be of great value and relevance for the existing (national) industrial setups.

Isolation-drug resistance profile and molecular characterization of indigenous typical and atypical mycobacteria.

One hundred and fifty mycobacterial isolates from different pathological Labs. of Karachi were collected and screened as acid fast. On the bases of phenotypic and biochemical results, it was found that, 58.66% isolates were typical mycobacteria while 41.33% belonged to atypical mycobacteria. The individual percentages of different mycobacterial species include: M. xenopi 35%, M. thermoresistible 19 %, M. terrae complex 6 %, M. marinum 6 %, M. fortuitum 6 %, M. kansasii 25 % and M. tuberculosis 58.66 %. The sensitivity of mycobacterial isolates was determined against 5 first line, 3 second line and 1 third line anti-tuberculosis drugs. The highest number of the isolates (typical and atypical mycobacteria) offered resistance against isoniazid and streptomycin. Clarithromycin was found to be the drug of choice as regards the drug sensitivity in case of atypical mycobacterial isolates. A total of 40 isolates were subjected to PCR based identification and differentiation of 16S rRNA gene(s). Accordingly, 37.5% isolates were identified as typical mycobacteria while 25% were identified as atypical mycobacteria. These findings carry significance because a detailed research based identification (PCR and Multiplex PCR based) regarding indigenous mycobacteria has been reported for the first time in Pakistan. However, both the approaches (conventional and molecular methods) have experimental importance while identifying these organisms.

Urinary tract infections associated with multidrug resistant enteric bacilli: characterization and genetical studies.

Urinary tract infections (UTIs) are among the most commonly prevalent infections in clinical practice. Escherichia coli is the causative agent in about 85% of community-acquired UTIs, followed by Klebsiella that accounts for 6 to 17% of such infections. Present study is based on the isolation-identification and antibiotic resistance pattern of about 60 indigenous bacterial isolates from UTI patients. Prevalence rates were consistent with those from major recent studies reported in the literature, i.e. 73% isolates were identified as E. coli, 16% as K. pneumoniae and 11% as Proteus sp. Bases of identification included morpho-cultural and biochemical characteristics. To assess the breadth of multidrug resistance among these isolates, culture medium incorporation method was employed using ampicillin, fosfomycin, chloramphenicol, tetracycline, and three aminoglycosides (kanamycin, gentamicin, and streptomycin). Of these isolates, 30% offered multidrug resistance to three or more agents. Among multidrug resistant isolates, 100% were resistant to ampicillin, 47% to streptomycin, 41% to chloramphenicol, gentamicin and tetracycline, 35% offered resistance to kanamycin while only 6% showed resistance to fosfomycin. After curing treatment with acridine orange, some of the isolates lost their resistance, thereby indicating the extrachromosomal location of the resistance determinants. Plasmid DNA (bearing multidrug resistant genes) was isolated from the uncured cells, and was stably transformed into the competent cured recipient cells.