Risk Factors for Stoma Outlet Obstruction after Proctocolectomy for Ulcerative Colitis.

Objectives: Stoma outlet obstruction (SOO) occurs with an incidence of approximately 40% after proctocolectomy for Ulcerative colitis (UC) with diverting ileostomy. This study aimed to identify the risk factors for SOO after proctocolectomy with diverting ileostomy for patients with UC. Methods: We reviewed the data of 68 patients with UC who underwent proctocolectomy and diverting ileostomy between April 2006 and September 2021. These cases were analyzed on the basis of clinicopathological and anatomical factors. SOO was defined as small bowel obstruction displaying symptoms of intestinal obstruction, such as abdominal distention, abdominal pain, insertion of a tube through the stoma. Results: The study included 38 (56%) men and 30 (44%) women with a median age of 42 years (range, 21-80). SOO categorized as at least Clavien-Dindo grade II occurred in 11 (16%) patients. Six patients required earlier stoma closure than scheduled. Compared with patients without SOO, patients with SOO had a significantly higher total steroid dose from the onset of UC to surgery (p = 0.02), a small amount of intraabdominal fat (p = 0.04), and a higher rate of laparoscopic surgery (p < 0.01). Conclusions: A high preoperative steroid dose, a small amount of intraabdominal fat and laparoscopic surgery were identified as risk factors for SOO. Early detection and treatment for SOO are important for patients at risk.

Clostridium paraputrificum Bacteremia in a Patient with Rectal Cancer after Receiving Antibiotic Therapy for Acute Pharyngolaryngitis.

Clostridium paraputrificum bacteremia is very rare, and its clinical importance is poorly understood. An 86-year-old man was receiving lascufloxacin therapy for acute pharyngolaryngitis before presenting to our emergency department with a recurrent fever. Two sets of blood cultures on admission revealed C. paraputrificum. A stool culture showed a reduced presence of intestinal commensal bacteria. After admission, the patient's fever resolved without antibiotics. Colonoscopy revealed a rectal tumor. Rectal tumor and microbial substitutions caused by antibiotics may have led to bacteremia. When treating C. paraputrificum bacteremia, physicians should be mindful of coexisting gastrointestinal disorders and a history of antibiotic administration.

Association of mitochondrial DNA haplogroup and hearing impairment with aging in Japanese general population of the Iwaki Health Promotion Project.

Age-related hearing loss (ARHL) is a complex multifactorial disorder. Studies in animals, including mitochondria-mutator mice, and in human suggest that oxidative stress and mitochondrial disturbance play an important role in the pathoetiology of ARHL. Mitochondrial DNA (mtDNA) haplogroups are populations with genetically similar traits, and they have been reported to affect the mitochondrial function of oxidative phosphorylation. To gain further insights into the relationships between mitochondrial haplotypes and the susceptibility to cochlear aging, in this study, we aimed to elucidate how the differences in mtDNA haplogroups may affect ARHL development in Japanese general population. We focused on early onset ARHL, as the same mtDNA haplogroup can show either a negative or positive effect on systemic co-morbidities of ARHL that appear later in life. A total of 1167 participants of the Iwaki Health Promotion Project were surveyed in 2014, and 12 major haplotype groups (D4a, D4b, D5, G1, G2, M7a, M7b, A, B4, B5, N9, and F) were selected for the analysis. A total of 698 subjects aged 30 to 65 years were included in the statistical analysis, and the hearing loss group consisted of 112 males (40.3%) and 111 females (26.4%). Multiple logistic regression analysis showed that the male subjects belonging to haplogroup A had a significantly increased risk of hearing loss, whereas the female subjects belonging to haplogroup N9 had a significantly decreased risk of hearing loss. These results suggested that the mtDNA haplogroup may be an indicator for future risk of morbidity associated with ARHL.

Correction to: Prevalence of the mitochondrial 1555 A>G and 1494 C>T mutations in a community-dwelling population in Japan.

[This corrects the article DOI: 10.1038/s41439-020-00115-9.].

Prevalence of the mitochondrial 1555 A>G and 1494 C>T mutations in a community-dwelling population in Japan.

Single nucleotide polymorphisms in mitochondrial DNA, such as mitochondrial 1555 A>G (m.1555 A>G) and mitochondrial 1494 C>T (m.1494 C>T), are known to be causative mutations of nonsyndromic hearing loss following exposure to aminoglycoside antibiotics. The prevalence of the m.1555 A>G and m.1494 C>T mutations has not been reported for the general population in Japan. The purpose of this study was to investigate the prevalence of m.1555 A>G and m.1494 C>T mutations in a community-dwelling population in Japan in order to prevent aminoglycoside-induced hearing loss. We recruited participants older than 20 years of age to the Iwaki Health Promotion Project in 2014, 2015, and 2016, resulting in the recruitment of 1,683 participants. For each participant, we performed a hearing test and a genetic test for the m.1555 A>G and m.1494 C>T mutations using the TaqMan genotyping method. The m.1555 A>G mutation was detected in only 1 of the 1,683 participants (0.06%). This carrier of the m.1555 A>G mutation was a 69-year-old male with bilateral, symmetric, and high-frequency hearing loss. We provided genetic counseling and distributed a drug card advising him to avoid the administration of aminoglycoside antibiotics. In contrast, the m.1494 C>T mutation was not detected in this study population.

UV-C-irradiation sublethal stress does not alter antibiotic susceptibility of the viridans group streptococci to ß-lactam, macrolide, and fluoroquinolone antibiotic agents.

AIM: Previous work has indicated that environmental stresses on bacteria might lead to an upregulation of stress response. LED curing lights (315-400 nm) and other UV lights used in tooth whitening cosmetic procedures might act as stresses. We examined the effect of UV-C light, as a high-energy surrogate to the lower-energy UV-A light used in such instruments, to examine its effect on the antibiotic susceptibility of viridans group streptococci. METHODS: Twelve species of viridans group streptococci were examined in this study: Streptococcus anginosus, Streptococcus australis, Streptococcus cristatus, Streptococcus gordonii, Streptococcus infantis, Streptococcus mitis, Streptococcus mutans, Streptococcus oralis, Streptococcus parasanguinis, Streptococcus pneumoniae, Streptococcus salivarius, and Streptococcus sanguinis. These organisms were exposed to varying degrees of sublethal UV-C radiation, and their minimum inhibitory concentration susceptibility was determined by broth dilution assay against three classes of commonly-used antibiotics: ß-lactams (penicillin), macrolides (erythromycin), and fluoroquinolones (ciprofloxacin). RESULTS: There was no significant difference between antibiotic susceptibility before UV-C exposure and following maximum sublethal stress, prior to cell death due to fatal UV-C exposure. CONCLUSIONS: Exposure to UV-C light will not result in altered antibiotic susceptibility patterns on viridans group streptococci. Given that UV-C is more toxic and mutagenic than UV-A light, it is unlikely than UV-A light would yield any difference in response to such exposure.

UVc-irradiation sublethal stress does not alter antibiotic susceptibility of staphylococci (MRSA, MSSA, and coagulase-negative staphylococci) to ß-lactam, macrolide, and fluoroquinolone antibiotic agents.

Skin tanning, either by exposure to natural sunlight or through use of UV sunbeds, has become a popular practice in the US, where it is estimated that approximately 1 million times per day someone in the US uses UV radiation for skin tanning, equating to 30 million Americans (circa 10% of the US population) who use a tanning bed. As well as exposing the host to periods of UV radiation, such practices also expose commensal skin bacteria, including Staphylococcus aureus, to such UV radiation. Previous work has indicated that environmental stresses on bacteria may lead to an upregulation of stress responses, in an attempt for the organism to combat the applied stress and remain viable. UV light may act as an environmental stress on bacteria, and so it was the aim of this study to examine the effect of UVc light on the antibiotic susceptibility of commensal skin bacteria, to determine if UV radiation would increase the antibiotic resistance of such skin flora and thus lead to a potential skin flora with increased antibiotic resistance. Previously, it has been shown that UVc light has a greater mutational effect on bacteria compared to lower-energy UV forms, including UVa and UVb light. Therefore, we decided to employ UVc light in our study to amplify the potential for mutational events occurring in skin staphylococci organisms (n=8) including methicillin-sensitive Staphylococcus aureus (n=2), methicillin-resistant Staphylococcus aureus (n=4), and coagulase-negative staphylococci (Staphylococcus haemolyticus) (n=2) were exposed to varying degrees of sublethal radiation via UVc light, and their minimum inhibitory concentration (MIC) susceptibility was determined by broth dilution assay against three classes of commonly used antibiotics, namely ß-lactams (penicillin), macrolides (erythromycin), and fluoroquinolones (ciprofloxacin). There was no significant difference between antibiotic susceptibility before UVc exposure and until maximum sublethal stress, prior to cell death due to fatal UVc exposure with the cells. These results indicate that UV environmental stress/exposure does not upregulate antibiotic resistance, and therefore these data indicate that UVc radiation does not lead to a more antibiotic-resistant population in the staphylococci organisms post-exposure.

Comparison of minimum inhibitory concentration by broth microdilution testing versus standard disc diffusion testing in the detection of penicillin, erythromycin and ciprofloxacin resistance in viridans group streptococci.

The aim of this study was to investigate the reliability of disc diffusion testing with penicillin, erythromycin and ciprofloxacin within the viridans group streptococci (VGS). In total, the antibiotic susceptibilities of 167 VGS isolates were compared by standard disc diffusion and broth microdilution methods, and these phenotypic data were compared to the carriage of the respective gene resistance determinants [ermB and mefA/E (macrolides); QRDR, gyrA, gyrB, parC and parE (quinolones)]. Overall, there were 35 discrepancies [resistant by MIC and susceptible by zone diameter (21.0%)] between MIC and disc diameter when penicillin susceptibility was interpreted by Clinical and Laboratory Standards Institute criteria. Scattergrams showed a bimodal distribution between non-susceptible and susceptible strains when erythromycin susceptibility was tested by both methods. Thirty-four (20.4%) isolates were categorized as resistant by MIC breakpoints, while disc diameter defined these as having intermediate resistance. With ciprofloxacin, three isolates (1.8%) showed minor discrepancies between MIC breakpoints and disc diameter. Isolates non-susceptible to all three antimicrobial agents tested were reliably distinguished from susceptible isolates by disc diffusion testing, except for the detection of low-level resistance to penicillin, where broth microdilution or an alternative quantitative MIC method should be used. Otherwise, we conclude that disc diffusion testing is a reliable method to detect strains of VGS non-susceptible to penicillin, erythromycin and ciprofloxacin, as demonstrated with their concordance to their gene resistance characteristics.

Identification and characterization of breakthrough contaminants associated with the conventional isolation of Mycobacterium tuberculosis.

Breakthrough contamination of tuberculosis (TB) cultures is a problem in that it allows the overgrowth of another bacterium present in the sputum specimen, which can potentially mask the presence of Mycobacterium tuberculosis. The aim of this study was to isolate and characterize the bacterial organisms responsible for such overgrowth and contamination, and to examine their susceptibility to (i) various chemical selective decontamination steps and (ii) antibiotics in liquid culture media, in an attempt to develop a method to help alleviate contamination problems associated with the conventional isolation of M. tuberculosis from routine patient sputum specimens. Bacterial contaminants from 102 routine sputum cultures were identified molecularly by 16S rRNA gene PCR and direct sequencing from contaminated Löwenstein-Jensen (LJ) slopes and BacT/Alert liquid medium. It was found that the contaminants from LJ slopes belonged to 11 different genera and were composed largely of Gram-negative organisms (84.9 %; 45/53), whereas the liquid culture contaminants belonged to 13 different genera, with 37/66 isolates (56.1 %) being Gram-negative. Pseudomonas aeruginosa was the dominant contaminant in both media. The effect of six different selective decontamination protocols was examined. Four of the six methods were effective at eliminating all culturable organisms present; these were 5 % oxalic acid, 5 % oxalic acid/2 % NaOH, 5 % oxalic acid/4 % NaOH and 1 % chlorhexidine. NaOH at a concentration of 2 or 4 % was less effective as it was unable to eliminate all organisms of each species tested, with the exception of P. aeruginosa. In conclusion, breakthrough contamination of TB cultures is due to a diverse range of at least 17 different bacterial genera, with P. aeruginosa and Staphylococcus epidermidis accounting for the dominant contaminating flora. Employment of chemical decontaminating protocols solely involving NaOH may lead to higher rates of contamination. Where such contamination is encountered, TB laboratories should consider the reprocessing of such sputum samples with an alternative decontamination method such as 1 % chlorhexidine.

Molecular characterization and phylogenetic analysis of quinolone resistance-determining regions (QRDRs) of gyrA, gyrB, parC and parE gene loci in viridans group streptococci isolated from adult patients with cystic fibrosis.

OBJECTIVES: Ciprofloxacin is the most frequently used member of the fluoroquinolones during initial eradication therapy of Pseudomonas aeruginosa, as well as during acute pulmonary exacerbations. However, its long-term effect on the susceptibility of the commensal flora within the cystic fibrosis (CF) airways has not yet been examined. The aim of this study was therefore to examine the consequence of oral ciprofloxacin usage on the resistance of the commensal viridans group streptococci (VGS), in terms of MICs and mutational analysis of the quinolone resistance-determining regions (QRDRs). METHODS: The MICs of ciprofloxacin, efflux activities and amino acid substitutions in the QRDRs for 190 isolates of VGS, originating from the sputa of adult CF patients who had been exposed constantly to ciprofloxacin, were examined. VGS organisms included Streptococcus salivarius, Streptococcus mitis, Streptococcus sanguinis, Streptococcus oralis, Streptococcus parasanguinis, Streptococcus infantis, Streptococcus gordonii, Streptococcus anginosus, Streptococcus cristatus, Streptococcus australis and Streptococcus mutans. Ciprofloxacin susceptibility was determined by broth microdilution and QRDRs within the gyrA, gyrB, parC and parE gene loci were explored using sequence analysis. RESULTS: Twenty-seven (14.2%) streptococcal isolates were resistant to ciprofloxacin (MICs ≥8 mg/L) and 21 (11.1%) had reduced susceptibility (MICs 4 mg/L). As a comparator, clinically non-significant and non-invasive VGS organisms were examined in 12 consecutive non-CF patients in the community, where no resistance to ciprofloxacin was observed. Five novel QRDR PCR assays were developed to elucidate mutations within the CF VGS population, where there were six positions, which corresponded to previously reported quinolone resistance responsible mutations, and eight novel potential QRDR resistance mutations. Double mutations in gyrA and parC/parE led to MICs of 16 to >64 mg/L, while single mutations in parC or parE resulted in MICs of 8-32 mg/L and 8 mg/L, respectively. The mean homologies of each species to Streptococcus pneumoniae R6 were: gyrA, 70.3%-95%; gyrB, 69.6%-96.2%; parC, 76.1%-94.8%; and parE, 70.7%-94.7%. The close relatives of S. pneumoniae, S. mitis and S. oralis, showed high similarity for all four genes (more than 86%). CONCLUSIONS: Treatment of P. aeruginosa with oral ciprofloxacin in patients with CF may concurrently reduce antibiotic susceptibility in the commensal VGS flora, where these organisms may potentially act as a reservoir of fluoroquinolone resistance gene determinants for newly acquired and antibiotic-susceptible pathogens, particularly the Streptococcus milleri group.

Population structure and characterization of viridans group streptococci (VGS) including Streptococcus pneumoniae isolated from adult patients with cystic fibrosis (CF).

A study was undertaken to examine the population structure of viridans group streptococci (VGS) in the sputum of adult patients with cystic fibrosis (CF). Freshly expectorated sputa (n=58) from 45 adult CF patients were examined by selective conventional culture on Mitis-Salivarius agar and yielded 190 isolates of VGS. Sequence analyses of the rpnB and 16-23S rRNA ITS genes identified these isolates to belong to 12 species of VGS and included S. anginosus, S. australis, S. cristatus, S. gordonii, S. infantis, S. mitis, S. mutans, S. oralis, S. parasanguinis, S. pneumoniae, S. salivarius and S. sanguinis. The most frequently VGS organism isolated was S. salivarius (47/190; 24.7%), followed by S. mitis (36/190; 19%), S. sanguinis (25/190; 13.2%), S. oralis (20/190; 11.0%), S. pneumoniae (19/190; 10.0%), S. parasanguinis (16/190; 8.4%), S. infantis (11/190; 5.8%), S. gordonii (7/190; 3.7%), S. anginosus (4/190; 2.1%), S. cristatus (2/190; 1.1%), S. australis (1/190; 0.5%), S. mutans (1/190; 0.5%) and S. agalactiae (1/190; 0.5%). All, but four, patients harboured at least one VGS species, which ranged from one to five streptococcal species, with a mean of 2.85 species per patient. There was no clonality at the subspecies level employing ERIC RAPD PCR. Antibiotic susceptibility was determined by Minimum Inhibitory Concentration (MIC) testing against penicillin, erythromycin and ciprofloxacin. Overall, resistance to penicillin with all VGS was 73/190 (38.4%) and 167/190 (87.9%) for erythromycin. With regard to ciprofloxacin, 27/190 (14.2%) were fully resistant, whilst a further 21/190 (11.1%) showed intermediate resistance, which equated to approximately three quarters (74.7%) of isolates being fully sensitive to this agent. In addition, as a comparator control population, we examined antibiotic susceptibility, as above, in a non-CF population comprising 12 individuals (50 VGS isolates), who were not receiving chronic antibiotics. In comparison, 8% and 38% of VGS isolates from non-CF individuals were resistant by disk susceptibility testing to penicillin and erythromycin, respectively. None of the non-CF VGS organisms were resistant to ciprofloxacin, but 42% showed intermediate resistance.

Molecular identification of airborne bacteria associated with aerial spraying of bovine slurry waste employing 16S rRNA gene PCR and gene sequencing techniques.

Polymerase chain reaction amplification of the universal 16S ribosomal RNA (rRNA) gene was performed on a collection of 38 bacterial isolates, originating from air sampled immediately adjacent to the agricultural spreading of bovine slurry. A total of 16 bacterial genera were identified including both Gram-positive and Gram-negative genera. Gram-positive organisms accounted for 34/38 (89.5%) of total bacterial numbers consisting of 12 genera and included Staphylococcus (most common genus isolated), Arthrobacter (2nd most common genus isolated), Brachybacterium, Exiguobacterium, Lactococcus, Microbacterium and Sporosarcina (next most common genera isolated) and finally, Bacillus, Brevibacterium, Frigoribacterium, Mycoplana and Pseudoclavibacter. Gram-negative organisms accounted for only 4/38 (10.5%) bacterial isolates and included the following genera, Brevundimonas, Lysobacter, Psychrobacter and Rhizobium. No gastrointestinal pathogens were detected. Although this study demonstrated a high diversity of the microorganisms present, only a few have been shown to be opportunistically pathogenic to humans and none of these organisms described have been described previously as having an inhalational route of infection and therefore we do not believe that the species of organisms identified pose a significant health and safety threat for immunocompetant individuals.

Molecular characterization of macrolide resistance determinants [erm(B) and mef(A)] in Streptococcus pneumoniae and viridans group streptococci (VGS) isolated from adult patients with cystic fibrosis (CF).

OBJECTIVES: Although long-term use of azithromycin has shown a significant clinical improvement for patients with cystic fibrosis (CF), its long-term effect on the susceptibility of commensal flora within CF airways has not yet been examined. We therefore suggest that long-term use of azithromycin increases macrolide resistance in commensal streptococci. METHODS: Erythromycin susceptibility in naturally colonizing viridans group streptococci (VGS) was characterized, as well as macrolide resistance gene determinants through sequence analysis, in pneumococci (n = 15) and VGS [n = 84; i.e. Streptococcus salivarius (n = 30), Streptococcus mitis (n = 17), Streptococcus sanguinis (n = 11), Streptococcus oralis (n = 10), Streptococcus parasanguinis (n = 6), Streptococcus gordonii (n = 3), Streptococcus infantis (n = 3), Streptococcus cristatus (n = 2), Streptococcus anginosus (n = 1) and Streptococcus australis (n = 1)] isolated from sputum from 24 adult CF patients, who were on oral azithromycin therapy for at least the previous 7 months. RESULTS: Almost three-quarters of isolates (74; 74.7%) were resistant to erythromycin, whilst a further 15 (15.2%) had reduced susceptibility, leaving only 10 (10.1%) isolates susceptible to erythromycin. The majority (89.8%) were not susceptible to erythromycin, as demonstrated by possession of the erm(B) gene in 25/99 (25.3%), the mef(A) gene in 1/99 (1.0%), the mef(E) gene in 75/99 (75.8%) and both erm(B) and mef(E) genes simultaneously in 11/99 (11.1%). These results indicate that genotypic resistance for macrolides is common in VGS in adult CF patients, with efflux being over three times more frequent. CONCLUSIONS: Long-term treatment with azithromycin in CF patients may reduce antibiotic susceptibility in commensal VGS, where these organisms may potentially act as a reservoir of macrolide resistance determinants for newly acquired and antibiotic-susceptible pathogens.

An examination of antibacterial and antifungal properties of constituents described in traditional Ulster cures and remedies.

Traditional herbal cures and remedies have played an important historical role in the treatment of a variety of illnesses and diseases in Northern Ireland for the last three hundred years. Recently, these have been reviewed in the publication by Linda Ballard from the Ulster Folk and Transport Museum at Cultra, Co. Down, which details the variety of local plants used and for what purpose. From this publication and another related publication, we note the description of several plant species that consistently appear in traditional cures and remedies, particularly used to treat infections and infectious diseases. Unfortunately, although these plants have strong associations with the local historical evidence base, there are very limited and mainly no formal publications in the medical/scientific evidence base, examining their scientific background and clinical efficacy.

An examination of antibacterial and antifungal properties of constituents of Shiitake (Lentinula edodes) and oyster (Pleurotus ostreatus) mushrooms.

BACKGROUND: Antibiotic agents have been in widespread and largely effective therapeutic use since their discovery in the 20th century. However, the emergence of multi-drug resistant pathogens now presents an increasing global challenge to both human and veterinary medicine. It is now widely acknowledged that there is a need to develop novel antimicrobial agents to minimize the threat of further antimicrobial resistance. With this in mind, a study was undertaken to examine the antimicrobial properties of aqueous extracts of 'exotic' Shiitake and Oyster mushrooms on a range of environmental and clinically important microorganisms. METHOD: Several batches of Shiitake and oyster mushrooms were purchased fresh from a local supermarket and underwent aqueous extraction of potential antimicrobial components. After reconstitution, aqueous extracts were tested qualitatively against a panel of 29 bacterial and 10 fungal pathogens, for the demonstration of microbial inhibition. RESULTS: Our data quantitatively showed that Shiitake mushroom extract had extensive antimicrobial activity against 85% of the organisms it was tested on, including 50% of the yeast and mould species in the trial. This compared favourably with the results from both the Positive control (Ciprofloxacin) and Oyster mushroom, in terms of the number of species inhibited by the activity of the metabolite(s) inherent to the Shiitake mushroom. CONCLUSIONS: This small scale study shows the potential antimicrobial effects of Shitake extracts, however further work to isolate and identify the active compound(s) now requires to be undertaken. Once these have been identified, suitable pharmaceutical delivery systems should be explored to allow concentrated extracts to be prepared and delivered optimally, rather than crude ingestion of raw material, which could promote further bacterial resistance.

Antibacterial activity of honey against community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA).

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has now been described globally, as a clinically significant pathogen, particularly associated with skin and soft tissue infections, including abscesses, cellulitis and furunculosis. The recent emergence of CA-MRSA combined with its predominant presentation associated with skin and soft tissue infection, the previous literature indicating honey as an effective treatment of healthcare-associated HA-MRSA-related wound infection, as well as honey's ease of topical application, make the current study timely and of interest to healthcare practitioners involved with wound management. Although previous studies have examined the antimicrobial activity of honey against HA-MRSA, such data are limited regarding the activity of honey against this emerging type of MRSA. CA-MRSA (n=6 isolates), was examined for its susceptibility to natural honey (n=3 honey produced from bees in Northern Ireland and one commercial French honey). Results demonstrated that all honey was able to reduce the cultural count of all CA-MRSA from approximately 10(6) colony-forming units (cfus) (mean = 6.46 log10 cfu/g) to none detectable within 24h of co-culture of separate CA-MRSA organisms individually with all four-honey types examined. Subsequent non-selective enrichment of honey demonstrated that inoculated honey remained positive for CA-MRSA until 72h postinoculation, after which point no culturable organisms could be detected. This study demonstrated that, in vitro, these natural products had an antimicrobial activity against the CA-MRSA organisms tested. Further studies are now required to demonstrate if this antimicrobial activity has any clinical application.

Bactericidal activity of denture-cleaning formulations against planktonic health care-associated and community-associated methicillin-resistant Staphylococcus aureus.

The aim of this study was to examine the survival dynamics of several epidemic health care-associated (HA) and community-associated (CA) methicillin-resistant Staphylococcus aureus (MRSA) in planktonic state in widely employed denture-cleaning solutions. The bacteriocidal activity of five widely employed denture-cleaning formulations were examined against five phage-types of HA-MRSA (EMRSA 15, EMRSA 16, Irish 1, Irish 2, unique type), as well as a CA-MRSA strain, in this study. Viable MRSA cells (circa 10(5) cfu/mL) were coincubated with optimum recommended working concentrations of denture-cleaning solutions for up to 17 hours (overnight). Recovery experiments were unable to isolate any of the inoculated MRSA organisms 10 minutes post inoculation. The significance and impact of this short study indicates that HA-MRSA and CA-MRSA are not able to remain culturable for 10 minutes in planktonic form, in commonly used denture-cleaning formulations widely available on the UK High Street, suggesting that these formulations may be useful in lowering the numbers of MRSA. Further work is however required to examine the more complex survival dynamics of MRSA in naturally derived denture biofilm, associated with dental plaque and the use of such cleaning formulations.