Six‑year susceptibility trends and effect of revised Clinical Laboratory Standards Institute breakpoints on ciprofloxacin susceptibility reporting in typhoidal Salmonellae in a tertiary care paediatric hospital in Northern India.

The antimicrobial trends over 6 years were studied, and the effect of revised Clinical Laboratory Standards Institute (CLSI) breakpoints (2012) for ciprofloxacin susceptibility reporting in typhoidal Salmonellae was determined. A total of 874 (95.4%) isolates were nalidixic acid‑resistant (NAR). Using the CLSI 2011 guidelines (M100‑S21), 585 (66.9%) isolates were ciprofloxacin susceptible. The susceptibility reduced to 11 (1.25%) isolates when interpreted using 2012 guidelines (M100‑S22). Among the forty nalidixic acid susceptible (NAS) Salmonellae, susceptibility to ciprofloxacin decreased from 37 isolates (M100‑S21) to 12 isolates (M100‑S22). The 25 cases which appeared resistant with newer guidelines had a minimum inhibitory concentration (MIC) range between 0.125 and 0.5 μg/ml. MIC50 for the third generation cephalosporins varied between 0.125 and 0.5 μg/ml over 6 years whereas MIC90 varied with a broader range of 0.19–1 μg/ml. The gap between NAR and ciprofloxacin‑resistant strains identified using 2011 guidelines has been reduced; however, it remains to be seen whether additional NAS, ciprofloxacin‑resistant isolates are truly resistant to ciprofloxacin by other mechanisms of resistance.

Changes in Antimicrobial Susceptibility of Blood Isolates in a University Hospital in South Korea, 1998-2010

BACKGROUND: Local epidemiologic data on prevalent pathogens are important to guide empirical antibiotic therapy. In this study, we observed annual changes in frequency of occurrence and in vitro antimicrobial susceptibility of blood isolates over a period of 13 years. MATERIALS AND METHODS: We reviewed blood isolates identified during the period from 1998 to 2010 at Seoul National University Hospital. Only first isolates for each patient were included in the analysis. We analyzed the frequency of isolates and their trend with regard to in vitro antimicrobial susceptibility. Data were presented according to guidelines of the Clinical and Laboratory Standards Institute (CLSI) (2009). RESULTS: A total of 23,501 isolates were identified during the period from 1998 to 2010. Fifty-five percent of the isolates were gram-positive cocci, 38% were gram-negative rods, and 3% were fungi. Coagulase-negative Staphylococcus (CoNS) (24%), Escherichia coli (16%), Staphylococcus aureus (10%), and Klebsiella pneumoniae (8%) were the most commonly isolated bacteria, and Candida albicans (2%) was the most commonly isolated fungus. The frequency of CoNS increased from 18.0% to 26.8%, whereas the frequency of E. coli and K. pneumoniae decreased from 20.2% to 13.7% and from 11.7% to 6.7%, respectively. Overall, the proportion of methicillin-resistant S. aureus changed from 47.9% to 62.1%. In E. coli, the resistance rate of cefotaxime and ciprofloxacin increased over a period of 13 years. However, such an increase of resistance was not observed in K. pneumoniae. In P. aeruginosa, and particularly in A. baumannii, resistance to imipenem rose alarmingly (3% in 1998 to 27.8% in 2010, 5% in 1998 to 68.9% in 2010, respectively). CONCLUSIONS: Over the last 13 years, the proportion of CoNS in blood isolates increased, which led to a relative decrease of isolated gram-negative rods. Proportions of MRSA showed no significant change, whereas cefotaxime resistant and ciprofloxacin resistant E. coli increased. Imipenem resistant P. aeruginosa and A. baumannii also increased during the study period.

A prospective microbial surveillance project at a major Italian Hospital: Epidemiological perspectives, and in vitro susceptibility rates

Microbiological surveillance program is currently performed at our tertiary-care teaching Hospital. The temporal trend of microbial isolates from patients admitted during the last four calendar years (2004 to 2007), has been analyzed according to the main bacterial and fungal cultured organisms. The same pathogens isolated more than once from the same patient within one month, have been considered only once. On the whole, the main pathogen group remained that of Enterobacteriaceae (6,608 isolations out of 19,666: 33.6%, with Escherichia coli retrieved in 60-75% of cases), with no significant difference over time. Staphylococci (4,150 isolates), and enterococci (3,276 isolates), were the two largest groups after Enterobacteriaceae, but staphylococci significantly declined during the examined four-year period (p<.001), mainly due to a progressively reduced isolation of coagulase-negative staphylococci. On the other hand, a slight increase of enterococci occurred (p<.05). Based on the frequency of isolation, Gram-negative oxydasepositive organisms accounted for 2,109 episodes, followed by other aerobe Gram-positive organisms other than Staphylococci-Enterococci (613 isolates), and anaerobes (583 isolates): no significant temporal variations occurred over time for these last microbial groups. With regard to Gram-negative oxydase-negative microorganisms (567 isolates), non-betahemolytic streptococci (464 cases), and beta-hemolytic streptococci (260 isolates), a significant trend towards a reduction of frequency occurred from the year 2004 to 2007 (p<.05 to p<.001)