Impact of antiseptics on Chlamydia trachomatis growth

Direct qPCR is a sensitive approach to detect Mycoplasma contamination in U937 cell cultures

OBJECTIVE

We aim to directly detect Mycoplasma DNA in a U937 suspension cell culture without using DNA purification. In order to make Mycoplasma contamination monitoring easier, we optimized a commercially available quantitative PCR (qPCR)-based detection kit. We compared the sensitivity of direct qPCR against qPCR with a purified DNA template.

RESULTS

Our findings indicate that qPCR worked optimally with a 6 μl sample volume and a 52 °C annealing-extension temperature. We were able to decrease the annealing-extension step time from 60 to 20 s without any major decrease in reaction sensitivity. The total cycle time of optimized direct qPCR was 65 min. The optimized qPCR protocol was used to detect Mycoplasma DNA before and after DNA purification. Our findings indicate that direct qPCR had a higher sensitivity than regular qPCR. Ct levels produced by direct qPCR with 6 μl templates were almost identical to Ct levels produced by regular qPCR with DNA purified from a 60 μl cell culture sample (23.42 vs 23.49 average Ct levels, respectively). The optimized direct qPCR protocol was successfully applied to monitor the elimination of Mycoplasma contamination from U937 cell cultures.

Antimicrobial Resistance Screening in Chlamydia trachomatis by Optimized McCoy Cell Culture System and Direct qPCR-Based Monitoring of Chlamydial Growth

Obligate intracellular localization of Chlamydia trachomatis (C. trachomatis) complicates antimicrobial sensitivity testing efforts that we are so accustomed to in routine bacteriology. Cell culture systems with immunofluorescence staining, to identify cellular inclusions in the presence of various concentrations of antimicrobial drugs, are still the most pervasive techniques, but more specific and sensitive nucleic acid concentration measuring methods are increasingly being used. Here we describe how to approach antimicrobial susceptibility/resistance screening in C. trachomatis by using a McCoy cell culture system, optimized by a research group from Croatia, and direct qPCR-based monitoring of chlamydial growth, optimized by a research group from Hungary.

In vitro efficacy of povidone iodine and hydroxyethyl cellulose, alone and in combination, against common feline ocular pathogens

Infectious ocular disease, such as conjunctivitis, is common in cats and can be caused by several viruses and bacteria, either as a single infection or as co-infections. In this study, povidone-iodine (PVP-I), alone or compounded with hydroxyethyl cellulose (HEC), was investigated for its efficacy against these pathogens in vitro. Whilst PVP-I alone was effective at inhibiting feline herpesvirus type 1 (FHV-1), Chlamydia felis, and Mycoplasma felis, PVP-I with HEC exerted a synergistic inhibitory effect against FHV-1 and C. felis. In contrast, only minimal inhibition of feline calicivirus was observed. These results demonstrate that PVP-I, alone and in combination with HEC, is effective against some feline ocular pathogens when tested in cell lines in vitro. In vivo studies investigating the systemic safety, ocular tolerance, and clinical efficacy of this combination in cats would be necessary before it could be recommended as a therapy in affected cats.

Nonactivated titanium-dioxide nanoparticles promote the growth of Chlamydia trachomatis and decrease the antimicrobial activity of silver nanoparticles

AIMS

Chlamydia trachomatis and herpes simplex virus (HSV) are the most prevalent bacterial and viral sexually transmitted infections. Due to the chronic nature of their infections, they are able to interact with titanium-dioxide (TiO₂ ) nanoparticles (NPs) applied as food additives or drug delivery vehicles. The aim of this study was to describe the interactions of these two prevalent pathogens with the TiO₂ NPs.

METHODS AND RESULTS

Chlamydia trachomatis and HSV-2 were treated with nonactivated TiO₂ NPs, silver NPs and silver decorated TiO₂ NPs before infection of HeLa and Vero cells. Their intracellular growth was monitored by quantitative PCR. Unexpectedly, the TiO₂ NPs (100 μg ml^-1 ) increased the growth of C. trachomatis by approximately fourfold, while the HSV-2 replication was not affected. Addition of TiO₂ to silver NPs decreased their antimicrobial activity against C. trachomatis up to 27·92-fold.

CONCLUSION

In summary, nonactivated TiO₂ NPs could increase the replication of C. trachomatis and decrease the antimicrobial activity of silver NPs.

SIGNIFICANCE AND IMPACT OF THE STUDY

The food industry or drug delivery use of TiO₂ NPs could enhance the growth of certain intracellular pathogens and potentially worsen disease symptoms, a feature that should be further investigated.