Trends of Antimicrobial Resistance of Sepsis Pathogens at a University Hospital in New Delhi, India.

Knowledge of the aetiological agents and its susceptibility to antimicrobial agents enables the clinician to initiate appropriate empirical antimicrobial therapy and guides diagnostic procedures. The aims of the study were to identify prevalence of bacterial pathogens causing sepsis and observe their antimicrobial resistance trends in hospitalized patients. A prospective cohort study was conducted on patients of sepsis admitted at a university hospital over a period of six months. Pathogens were identified by morphological, biochemical and serological tests as per the American Society for Microbiology. Antibacterial sensitivity of bacterial strains isolated from clinically diagnosed sepsis was carried out by Kirby-Bauer disk diffusion method and interpreted according Clinical and Laboratory Standards Institute guidelines. The data were analyzed by using Statistical Package for Social Sciences, version 16.0 (SPSS 16.0, Chicago, IL, USA). Coagulase negative Staphylococcus (63.5%) and Staphylococcus aureus (23.1%) were the most frequently isolated Gram positive bacteria. Acinetobacter species (31%) and Salmonella typhi (24.1%) were the most frequently isolated Gram negative bacteria. Coagulase negative Staphylococcus showed significant resistance to ciprofloxacin and tetracycline. Acinetobacter species showed significant resistance to ampicillin, amoxicillin and amoxiclav. Salmonella typhi showed significant resistance to ampicillin, amoxicillin, cefotaxime, netilmicin and, tetracycline. Escherichia coli showed significant resistance to ampicillin and netilmicin. All the stains of Staphylococcus aureus were resistant to amoxicillin. Coagulase negative Staphylococcus and Acinetobacter species were predominant Gram positive and Gram negative bacteria, respectively, causing sepsis. Increasing rates of bacterial resistance to commonly use antimicrobial agents were observed.

Minimum inhibitory concentration of carbapenems and tigecycline against Salmonella spp.

Antimicrobial resistance in Salmonella spp. is of grave concern, more so in quinolone-resistant and extended-spectrum beta-lactamase (ESBL)-producing isolates that cause complicated infections. The MIC of azithromycin, ciprofloxacin, cefixime, cefepime, ceftriaxone, gatifloxacin, imipenem, levofloxacin, meropenem and ofloxacin (E-test strip) and tigecycline and faropenem (agar dilution) against 210 Salmonella spp. was determined. MIC(90) (defined as the antimicrobial concentration that inhibited growth of 90 % of the strains) of the carbapenems (imipenem and meropenem) for Salmonella Typhi and Salmonella Paratyphi A was 0.064 microg ml(-1). MIC(90) of faropenem was 0.25 microg ml(-1) for S. Typhi, S. Paratyphi A and Salmonella Typhimurium. The MIC(90) of azithromycin for all Salmonella spp. ranged from 8 to 16 microg ml(-1). Tigecycline showed an MIC(90) of 2 microg ml(-1) for S. Typhi, 1 microg ml(-1) for S. Paratyphi A and 4 microg ml(-1) for S. Typhimurium. We concluded that tigecycline and the carbapenems are likely to have roles in the final stage of treatment of quinolone-resistant and ESBL-producing multidrug-resistant salmonellae.

In vitro evaluation of a new cefixime-clavulanic acid combination for gram-negative bacteria.

The study was conducted to evaluate a new cefixime-clavulanic acid combination for in vitro susceptibility towards gram-negative bacteria. A total of 220 isolates of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeroginosa, Acinetobacter spp, Salmonella enterica serovar Typhi and Salmonella enterica serovar Typhimurium were included in the study. The isolates were tested for susceptibility towards the new combination antimicrobial molecule cefixime with clavulanic acid by disk diffusion and Epsilometer strip (E-strip) Minimum Inhibitary Concentration (MIC) method. Of the 101 E. coli and K. pneumoniae isolates, 62.4% were found to be extended spectrum beta-lactamase (ESBL) producers. Almost half of these were from the community and 55.6% were hospital isolates. Of the ESBL isolates, 19% were AmpC (cephalosporinases that are poorly inhibited by beta lactamase inhibitor) producers while the remaining 81% were non AmpC ESBL producers. The AmpC producers were resistant to both cefixime and the combination, while the non-AmpC producers were sensitive to the combination. The addition of clavulanate to cefixime did not improve the sensitivities of P. aeruginosa and Acinetobacter isolates. There were no ESBL isolates among the S. Typhi isolates, all of which were sensitive to cefixime. Of the S. Typhimurium, 88.9% were ESBL producers and all of these were resistant to cefixime but sensitive to the combination. The combination of cefixime with clavulanic acid offers the advantage of oral administration and appears to be a viable option for the treatment of uncomplicated community acquired infections caused by non-AmpC ESBL producing gram-negative bacteria.

In vitro activity of azithromycin, newer quinolones and cephalosporins in ciprofloxacin-resistant Salmonella causing enteric fever.

The therapeutic alternatives available for use against ciprofloxacin-resistant enteric fever isolates in an endemic area are limited. The antibiotics currently available are the quinolones, third-generation cephalosporins and conventional first-line drugs. In this study, the MICs of various newer drugs were determined for 31 ciprofloxacin-resistant enteric fever isolates (26 Salmonella enterica serovar Typhi and 5 S. enterica serovar Paratyphi A). MICs for ciprofloxacin, ofloxacin, gatifloxacin, levofloxacin, cefotaxime, cefixime, cefepime and azithromycin were determined using Etest strips and the agar dilution method. By Etest, all of the ciprofloxacin-resistant isolates had ciprofloxacin MICs >/=32 mug ml(-1). S. Typhi showed MIC(90) values of 0.50, 0.25 and 0.38 mug ml(-1) for cefixime, cefotaxime and cefepime, respectively. For the cephalosporins, a negligible difference in MIC(90) and MIC(50) values for S. Typhi and S. Paratyphi A was observed. A single isolate of S. Typhi showed a high azithromycin MIC of 64 mug ml(-1). The MIC(90) value for azithromycin in S. Typhi and S. Paratyphi was 24 mug ml(-1). Gatifloxacin demonstrated lower resistance (80.8 %) compared with the other quinolones (92-100 %) in S. Typhi. The rise in MIC levels of these antimicrobials is a matter for serious concern.