No abstract

Respiratory infections (RI) can be viral or bacterial in origin. In either case, the invasion of the pathogen results in production and release of various volatile organic compounds (VOCs). The present study examines the VOCs released from cultures of five viruses (influenza A, influenza B, adenovirus, respiratory syncitial virus and parainfluenza 1 virus), three bacteria (Moraxella catarrhalis, Haemophilus influenzae and Legionella pneumophila) and Mycoplasma pneumoniae isolated colonies. Our results demonstrate the involvement of inflammation-induced VOCs. Two significant VOCs were identified as associated with infectious bacterial activity, heptane and methylcyclohexane. These two VOCs have been linked in previous studies to oxidative stress effects. In order to distinguish between bacterial and viral positive cultures, we performed principal component analysis including peak identity (retention time) and VOC concentration (i.e. area under the peak) revealing 1-hexanol and 1-heptadecene to be good predictors.

Antimicrobial drugs have an important role in controlling bacterial infectious diseases. However, the increasing resistance of bacteria to antibiotics has become a global health care problem. Rapid determination of antimicrobial susceptibility of clinical isolates is often crucial for the optimal antimicrobial therapy. The conventional methods used in medical centers for susceptibility testing are time‐consuming (>2 days). Two bacterial culture steps are needed, the first is used to grow the bacteria from urine on agar plates to determine the species of the bacteria (~24 hours). The second culture is used to determine the susceptibility by growing colonies from the first culture for another 24 hours. Here, the main goal is to examine the potential of infrared microscopy combined with multivariate analysis, to reduce the time it takes to identify Escherichia coli susceptibility to antibiotics and to determine the optimum choice of antibiotic to which the bacteria will respond. E coli colonies of the first culture from patients with urinary tract infections (UTI) were examined for the bacterial susceptibility using Fourier‐transform infrared (FTIR). Our results show that it is possible to determine the optimum choice of antibiotic with better than 89% sensitivity, in the time span of few minutes, following the first culture.

In conclusion, a sevenfold increase in laboratory-confirmed CL was observed in southern Israel in 2007-2013, probably reflecting a bigger outbreak, possibly related to urban expansion bordering with CL foci.