Antimicrobial sensitivity pattern of bacterial pathogens in urinary tract infections in South Delhi, India.

Seventy-four bacterial proven cases of urinary tract infections were studied, and identified by Mac Conkey agar and blood agar medium separately; all the isolates were subjected to antimicrobial sensitivity testing by Stokes technique. Ninty-six percent of total isolated organisms were found to be gram negative while remaining 4% were gram positive. Among gram negatives, E. coli and gram positive S. aureus were the most prevalent organisms. The percentage of gram negative isolates were as follows, E. coli (79.7%) followed by Klebsiella (9.5%), Pseudomonas, Acinetobacter were (2.7% each), Proteus constituted (1.4%). and among gram positive S. aureus (4%). The antibiotic resistance of identified organisms was carried out by disc-diffusion method with commercially available disc of thirteen antibiotics having different mode of actions such as inhibition of cell wall synthesis, membrane permeability alternatives, inhibition of protein synthesis and DNA synthesis inhibitors. Gram negatives showed more resistance to these antibiotics as compared to gram positive organisms. The most effective antibiotic for gram negative UTI isolates is amikacin showing 63% efficacy followed by Cefotaxime 55% efficacy, Amoxicillin and Ciprofloxacin with (49% each) efficacy. Among gram positives, Chloramphenicol, Co-trimoxazole, Gentamicin, Amikacin, Ciprofloxacin and Cefotaxime are most effective with (66.6% each) efficacy, then Ampicillin, Amoxicillin, Tetracycline and norfloxacin with (33.3% each) efficacy.

Antimicrobial therapy and outcome of septicemia patients admitted to a University Hospital in Delhi.

Septicemia is a common clinical condition encountered in most of the hospitals in this region of the world. However, limited information is available in the Indian literature on antimicrobial usage in patients with suspected or proven cases of septicemia. The aim of the present study is on the one hand to describe the clinical characteristics of septicemia, the causative pathogens, the current pattern of antimicrobial use, the clinical outcome, the acquisition cost of commonly used antimicrobial regimens and on the other hand to monitor adverse drug reactions (ADRs) during therapy of septicemia patients admitted to a University Hospital in Delhi. We prospectively reviewed the antimicrobial therapy in 34 clinically diagnosed septicemia cases admitted to a University Hospital from July 2009 to December 2009. All study patients presented various clinical signs and symptoms, fever, diarrhoea and vomiting were most commonly reported. Microorganisms could be identified in 13 (38.2%) of the patients. Escherichia coli (41.2%) constituted the most prevalent bacterial pathogen. Among culture positive patients, 15.4% received ceftriaxone as the most common empirical antimicrobial therapy; among culture negative patients, 19% received cefotaxime plus amikacin as the most common empirical antimicrobial therapy. The average acquisition cost of the 1st line antimicrobial regimen was higher in culture positive than in culture negative patients, but it was reversed for the 2nd line therapy. Overall, 67.6% patients were discharged after recovery, 23.5% were transferred out and 8.8% died during the course of therapy. 9 (26.5%) patients experienced ADRs during the antimicrobial therapy. These findings may have an important implication for developing comprehensive, evidence-based guidelines for the practical treatment of septicemia, adherence to which may lead to a more rational antimicrobial therapy, to cost reduction and to an improved level of care of patients with septicemia.

Resistant patterns of bacteria isolated from bloodstream infections at a university hospital in Delhi.

BACKGROUND: The choice of antimicrobial therapy for bloodstream infections is often empirical and based on the knowledge of local antimicrobial activity profiles of the most common bacteria causing such infections. AIMS: The present study was aimed to investigate frequency of bacterial pathogens causing septicemia and their antimicrobial resistant pattern in hospital admitted patients. SETTINGS AND DESIGN: It was a prospective study, conducted at Majeedia Hospital, Hamdard University, New Delhi, India. MATERIAL AND METHODS: We examined prospectively, 168 bacterial strains isolated from 186 clinically diagnosed septicemia cases admitted at a University Hospital in New Delhi, over a period of six months from July 2009 to December 2009. Antimicrobial susceptibility was performed according to Clinical and Laboratory Standards Institute (CLSI, USA) guidelines. RESULTS: The most frequently identified Gram-positive bacteria were coagulase-negative staphylococci 63.5%, Staphylococcus aureus 23.1%, enterococci 5.8% and alpha-haemolytic streptococci 5.8%. The most frequently Gram-negative bacteria identified were Acinetobacter species 31%, Salmonella typhi 24.1%, Escherichia coli 23.3% and Pseudomonas aeruginosa 13.8%. Coagulase-negative staphylococci showed maximum resistance to cefaclor 57.1% and ampicillin 46.9%. Staphylococcus aureus showed maximum resistance to amoxicillin 100% and ampicillin 91.7%. Acinetobacter species showed maximum resistance to amoxicillin 89.7%, amoxiclav 87.1% and ampicillin 85.7%. Salmonella typhi, Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae showed maximum resistance to ampicillin, 46.4%, 92%, 93.8% and 100%, respectively. CONCLUSIONS: Gram-negative pathogens predominated in bloodstream infections. Resistance to most of the antimicrobial agents for a number of pathogens implicated in bloodstream infections, especially in Gram-negative bacteria, has reached worrisome levels and continues to increase.

Molecular analysis of high-level ciprofloxacin resistance in Salmonella enterica serovar Typhi and S. Paratyphi A: need to expand the QRDR region?

Fourteen strains of S. Typhi (n=13) and S. Paratyphi A (n=1) resistant to ciprofloxacin were compared with 30 ciprofloxacin decreased-susceptibility strains on the basis of qnr plasmid analysis, and nucleotide substitutions at gyrA, gyrB, parC and parE. In ciprofloxacin-resistant strains, five S. Typhi and a single S. Paratyphi A showed triple mutations in gyrA (Ser83-->Phe, Asp87-->Asn, Glu133-->Gly) and a novel mutation outside the quinolone resistance determining region (QRDR) (Met52-->Leu). Novel mutations were also discovered in an isolate (minimum inhibitory concentration 8 microg/ml) in gyrA gene Asp76-->Asn and outside the QRDR Leu44-->Ile. Out of 30 isolates with reduced susceptibility, single mutation was found in 12 strains only. Genes encoding qnr plasmid (qnr A, qnr B, AAC1-F) were not detected in ciprofloxacin-resistant or decreased-susceptibility strains. Antimicrobial surveillance coupled with molecular analysis of fluoroquinolone resistance is warranted for reconfirming novel and established molecular patterns of resistance, which is quintessential for reappraisal of enteric fever therapeutics.

Enterotoxin production and plasmid profiles in Salmonella typhimurium isolated from man.

One hundred twenty-six isolates of Salmonella typhimurium from various clinical sources were tested for enterotoxin production and characterization of plasmid profile. Cell-free culture supernates and polymyxin B extracts of all the strains were assayed by rabbit ileal loop and skin permeability tests. Enterotoxic activity was detected in culture supernates of 32 strains. Twenty-one strains by both rabbit ileal loop and skin permeability tests, nine strains by skin permeability test, and two strains by rabbit ileal loop test were positive. Live culture of three enterotoxic strains, positive in culture supernates produced ileal secretion. Polymyxin B extracts from 6 hours and 18 hours broth cultures of all the strains were devoid of enterotoxicity. Ileal mucosa exposed to culture supernate of enterotoxigenic strains showed swollen and blunted villi with submucosal oedema while those exposed to polymyxin B extracts showed shortening of villi and sloughing of epithelial lining. Plasmid profiles of enterotoxigenic strains were heterogenous and grouped into 20 different profiles. No correlation could be established between plasmid profile, R-pattern, and enterotoxin production.

Plasmid profile and phage type of Salmonella typhimurium strains encountered in different regions of India.

A total of 190 Salmonella typhimurium strains encountered in different parts of India were characterized on the basis of plasmid profile, phage type and antimicrobial resistance pattern. Recent trends in the epidemiology of R-plasmids were also studied. The majority of S. typhimurium strains (90.5%) were untypable by phage typing. Only 18 strains (9.5%) were phage typable. The phage untypable strains isolated from northern (57) central (65), and southern (50) regions of India could be subgrouped into 24, 12 and 16 different plasmid profiles respectively. Heterogeneity was the prominent feature although most of the plasmid profiles were related among strains isolated from particular place. A great diversity among small plasmids (2.7-8.3 kb) made subgrouping of majority strains (71%) with R-pattern ApCmKmSmSuTcTp possible. Conjugation studies and plasmid profile analysis of transconjugants revealed all the strains to harbour non conjugative non-auto transmissible plasmids with the exception of 7.2 and 2.7 kb plasmids which were not mobilizable.

Plasmid profiles, adhesive & invasive properties of Salmonella ser. Typhimurium strains: phage types 99 & 36.

Adhesive and invasive properties were compared with plasmid profile in S. Typhimurium strains of phage type 99(10) and 36(10). All strains of phage type 99 were multiple drug resistant (ApCmKmSmSuTcTp) and harboured small plasmids of 2.4-5.2 MDal. Six strains of the phage type 36 had ApCmTc R-pattern and two with only ampicillin resistance, carried plasmids of molecular size 2.6-5.2 MDal; two strains were sensitive to all antibiotics and devoid of plasmids. None of the strains were found to harbour high molecular weight plasmids. All plasmid positive strains of phage types 99 and 36 could be divided into two groups of three plasmid patterns each, which were phage type specific. All plasmid positive and negative strains adhered and invaded HeLa cells to different degrees. No correlation could be established between plasmid profile and adhesion invasion characteristics. High molecular weight plasmids therefore are unlikely to be essential for adhesion and invasion.

Plasmid profile analysis of Salmonella ser. Typhimurium phage untypable strains encountered in diverse geographic regions of India.

Plasmid profile analysis and antibiotic resistance pattern determination were carried out for 117 phage untypable S. Typhimurium strains. Majority of the strains (82%) were resistant to all the seven antibiotics tested, R-pattern being ApCmKmSmSuTcTp, rest (12%) showed heterogenous R-patterns. Plasmid DNA analysis revealed phage untypable strains to harbour large (58.8-114.3 MDal), intermediate size (36 MDal, 42 MDal) and small (1.8-5.2 MDal) plasmids with varying molecular weights. All the phage untypable strains could be subgrouped by plasmid profile analysis into 23 plasmid patterns. Plasmid profile analysis could discriminate large number of phage untypable strains on the basis of their plasmid pattern.

Current status of drug resistance & phage types of Salmonella typhi in India.

A total of 11391 strains of S. typhi were received at the National Salmonella Phage Typing Centre at New Delhi during January 1990- August 1992, from various regions of India. Of these, 39.7 per cent were from north India, 37.5 per cent from central India and 22.8 per cent from south India. 64.5 per cent of S. typhi were found to be multidrug resistant (MDR), maximum resistance being observed in 1991 (71.6%) while it was least in 1990 (50.05%). There was a slight decline in the percentage of MDR strains in 1992. Region-wise analysis of the resistant strains showed maximum number in central India (71.32%), whereas it was least in the south (55.2%); 62.34 per cent of strains received from north India were MDR. Irrespective of the year or region, the predominant resistance pattern remained AMCSXTTE. The commonest phage type was E1, followed by 0 and A. This pattern was also seen in the MDR S. typhi. Certain degraded Vi strains, untypable Vi strains and Vi negative strains were also multidrug-resistant. An important change observed in this study was that a small number of strains belonging to phage types C1, K1, 28, 40, 41 and 42 which were always sensitive earlier, had developed multidrug resistance. Small outbreaks due to one phage type (e.g., 28 and 51) were short lived and subsided spontaneously. More diversity of phage types was observed in north India as compared to central and south India.

Duodenal string test in typhoid fever.

Twenty five children between 4-12 years of age hospitalized with a clinical diagnosis of enteric fever were studied for evaluating the practicality and sensitivity of duodenal string-capsule culture (DSCC) and compared with conventional cultures from blood (BC), urine (UC) and stool (SC). Duodenal string capsule (DSCC) was successfully inserted in 18 patients (72%). Insertion of DSCC failed in 7 patients (28%) and all of them were below 6 years of age. Salmonella typhi was isolated from DSCC and/or BC in 13 cases (72.2%). DSCC was positive in 11 out of 13 confirmed cases of typhoid fever (84.6%). BC was positive in 8 cases (61.5%). DSCC was successful in isolating the organism in about 30% more cases than BC. Duodenal string test was a simple, non-invasive and a reliable test which when used in combination with BC could identify almost all cases of enteric fever irrespective of duration of fever and prior use of antibiotics.

Multidrug resistant typhoid fever: therapeutic considerations.

Forty six blood culture positive cases were studied during the current outbreak of multidrug resistant typhoid fever (MRTF). The present outbreak was caused by E1 phage type and organisms were resistant to all commonly used drugs for the treatment of typhoid fever, viz., chloramphenicol (78%), co-trimoxazole (76%) and ampicillin (68%). Treatment failures with chloramphenicol (45.5%) corroborated well with in vitro resistance. No treatment failure was seen with chloramphenicol and ceftriaxone, when these drugs were used in cases infected with sensitive strains. Among the alternative drugs used in cases with in vitro sensitivity, successful clinical response was seen with ceftriaxone (4/4) and cefotaxime (8/9) as compared to cephalexin (3/5) or a combination of cephalexin and furazolidone (9/12).

Real-time image processing using selective erasure in photorefractive two-wave mixing.

We describe a real-time image-processing scheme that uses selective erasure of spatial frequencies at the Fourier transform plane in an arrangement employing photorefractive two-beam coupling. The versatility of the device results from the use of the Fourier transform of the erasure beam, which counterpropagates to the image-bearing beam. The technique can perform spatial-filtering operations such as edge enhancement, bandpass filtering, and pattern recognition by controlling the information available at the erasure-beam Fourier plane. An experimental demonstration has been made on edge enhancement, bandpass filtering, and character recognition.

A clinical profile of multidrug resistant typhoid fever.

Fifty blood culture positive patients of typhoid fever were studied during the current outbreak of the disease for their clinical profile. In 39 (78%) cases the isolates of S. typhi were resistant to conventional drugs. Children below 2 years of age constituted 20% of the total cases and belonged exclusively to the group with multidrug resistant typhoid fever (MRTF). The clinical presentation seemed to mimic malaria, bronchopneumonia, meningitis, etc. Typhoid hepatitis was diagnosed in 2 cases with MRTF. Life threatening complications were seen in 28.2% patients and were observed exclusively in MRTF group.

High-gain, low-noise signal beam amplification in photorefractive BaTiO(3).

We describe a pulse readout technique for high gain and a high signal-to-noise ratio (SNR) in signal beam amplification by two-beam coupling in a photorefractive BaTiO(3) crystal. The basic idea behind the technique is the formation of photorefractive gratings using a low-intensity pump beam and subsequent readout of this grating with a strong pulse for a duration that is less than the time constant for noise development or beam fanning. Large values ( approximately 11,000) of the signal beam gain and SNR's of approximately 1300 are achieved. A noise-free image amplification is the main achievement of this technique.

Enhanced holographic image intensification in BaTiO(3) photoelectrets.

We report an enhanced holographic image amplification gain of over 24,000 at a wavelength of 514.5 nm by using a BaTiO(3) photoelectret. The energy-transfer efficiency and amplification factor are found to depend on critical polarization conditions of the photoelectret, the beam-mixing geometries, and the intensity ratios between the reference and the object beams. The results obtained corresponding values reported previously.