Significant Difference In Colony-forming Units Research Articles

In Vitro and In Vivo Testing of Microbe Growth on Antimicrobial Nursing Scrubs.

Around 5% to 10% of hospitalized patients develop a hospital-acquired infection (HAI). Scrubs are a potential vector of HAIs. To compare the antimicrobial characteristics of scrubs with and without an antimicrobial fabric coating, as tested in the laboratory (in vitro) and hospital (in vivo) environments. Two protocols were conducted to address the purpose. The in vitro protocol was a laboratory study that involved observing the microbe growth after inoculating coated and uncoated scrub fabric swatches with S. aureus and then processing them in moist and dry environments. The in vivo protocol was a clinical trial that measured microbe growth on coated and uncoated scrubs prior to and following nursing staff completing a 12-hr shift on an acute care unit, as measured by colony forming units (CFUs). For high-humidity environments, the in vitro study indicated that swatches treated with an antimicrobial coating exhibited minimal microbe growth, while untreated swatches exhibited significant microbe growth. For low-humidity environments, coated and uncoated swatches were all found to exhibit minimal microbe growth. In the in vivo study, the CFUs increased on scrubs worn by nurses over a 12-hr shift with no significant difference in CFUs for coated and uncoated scrubs. For bacteria in a warm and moist environment, the antimicrobial coating was found to be important for inhibiting growth. For bacteria in a warm and dry environment, both coated and uncoated fabrics performed similarly as measured at 24 hr, with minimal bacterial growth observed. In a hospital environment, microbe growth was observed, but no significant difference was detected when comparing coated and uncoated scrubs. This may have been due to the short time between exposure and culturing the scrubs for analysis immediately at the end of the shift not allowing for enough time to kill or inhibit growth. Contact time between the bacteria and scrub fabric (coated or uncoated) in the in vivo study more directly correlated with the 0-hr observations for the in vitro study, suggesting that the ineffectiveness of the treated scrubs in the clinical results may be due in part to short residence times before collection.

Preliminary assessment of bacterial antibiotic resistance and Candidatus Liberibacter asiaticus titer in three Florida commercial citrus groves

Over the last 16 years, the U.S. citrus industry has been devastated by citrus greening or Huanglongbing (HLB) disease. The causal agent, Candidatus Liberibacter asiaticus (CLas), is an unculturable bacterium transmitted by the invasive Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Liviidae), and by grafting. In 2017 and 2019, the Environmental Protection Agency approved foliar applications of the antibiotics streptomycin (STR) and oxytetracycline (OTC) in commercial citrus groves in Florida. This study provides a preliminary assessment of antibiotic spray effects on three commercial citrus groves by quantifying CLas titer from leaves and antibiotic resistant bacterial colony count from leaf, root+rhizosphere, and soil samples. Two groves used antibiotic spray treatment and followed conventional management, one used no antibiotic treatment and was accredited as an organic grove. Samples were plated onto TSA medium containing either STR (100 μg/mL), OTC (15 μg/mL), or no antibiotic (control) then colony-forming units (CFU) per gram of sample were estimated. Among leaf samples, there were no significant differences in CFU or CLas titer based on grove. For soil samples, we found a larger number of resistant CFU in the organic grove. Root+rhizosphere samples from all groves (organic and conventional) showed high prevalence of both STR and OTC-resistant bacteria indicating that plant selective processes during root colonization might favor antibiotic resistant acquisition. The lack of significant difference in CLas titer among the three groves is supported by other studies which suggest that antibiotic spray might not be an effective control for CLas. This research further highlights the need for continued monitoring of antibiotic efficacy to control plant pathogens in commercial settings.

Effect of fenestrated sterile drape and face mask on bacterial dispersion toward the periocular area during intravitreal injection

This experimental crossover study was performed to investigate whether fenestrated surgical drapes (covering the nose and mouth but with an opening over the periorbital area) with or without patients’ surgical face masks increase periorbital bacterial dispersion during simulated intravitreal injection conditions. Each of the 16 healthy volunteers performed 14 scenarios involving different mask and drape conditions in both silent and speaking situations. In each scenario, the subject lay down flat on the back with a blood agar plate being held at the inferior orbital rim perpendicular to the face to capture airflow from breathing/speaking. Another blood agar plate placed 50 cm away from the subject served as an experimental control. A total of 224 experiments were performed. Speaking situations significantly showed more colony forming units (CFUs) compared with their controls (P = 0.014). There were no significant differences in CFUs between wearing vs not wearing the masks (P = 0.887 for speaking and P = 0.219 for silent) and using vs not using the drapes (P = 0.941 for speaking and P = 0.687 for silent). Reusable and disposable drapes were also not significantly different (P = 1.00 for speaking and P = 0.625 for silent). Streptococcus spp., the oropharyngeal microbiota, were only cultivated from speaking scenarios. While refraining from speaking (for both practitioners and patients) is the mainstay of reducing bacterial dispersion and risks of post-injection endophthalmitis, the use of fenestrated surgical drapes or patients’ face masks did not significantly affect the amount of bacterial dispersion toward the periorbital area.

Zinc-Impregnated Mesh for Abdominal Wall Repair Reduces Infection in a Rat Model of Peritonitis

BackgroundThe objective of this study was to assess whether a zinc-impregnated polypropylene mesh (ZnMesh) has better antibacterial properties in a contaminated environment compared with a regular polypropylene mesh. Materials and methodsThirty-eight Wistar Han rats underwent cecal ligation and puncture to induce peritonitis 24 h before implantation of an intraperitoneal ZnMesh or a regular polypropylene mesh. Primary outcome was the number of colony forming units (CFU) per sample (mesh and abdominal wall). Secondary outcomes were macroscopic (incorporation of mesh, abscesses, and adhesions on mesh surface) and histological (inflammatory cell reaction, mesh-specific parameters, and collagen deposition) parameters. All outcomes were evaluated after 30 and 90 d. ResultsAfter 30 d, no significant difference in CFU per sample was present between the ZnMesh and control groups. After 90 d, a lower number of CFU per sample was present in the ZnMesh group compared with the control group (trypticase soy agar with 5% sheep blood: 0 log10 CFU/sample IQR: 0-1.40 versus 1.58 log10 CFU/sample IQR: 0-4.30, P = 0.012; MacConkey: 0 log10 CFU/sample IQR: 0-2.65 versus 1.18 log10 CFU/sample IQR: 0-4.04, P = 0.438). After 90 d, the percentage of adhesions on mesh surface was significantly higher in the ZnMesh group (95% IQR: 60%-100% versus 50% IQR: 23%-75%, P = 0.029). No differences were seen in other macroscopic outcomes or histology. ConclusionsA significantly lower number of CFU per sample was found in the ZnMesh group after 90 d. After 30 d, no statistically significant differences in CFU per sample were seen. This result suggests that the ZnMesh group has better antibacterial properties in a contaminated environment. However, this is at the cost of a significantly higher percentage of adhesions.

Is a 10-minute surgical scrub necessary in urologic prosthetic surgery? A randomized study of the effect of a 5- vs 10-minute surgical scrub on bacterial colony counts in the genital skin.

To determine the antiseptic efficacy on bacterial colony counts of a 5- vs 10-minute surgical site scrub in urologic surgery. A prospective cohort study was conducted in 101 patients presenting for elective urological procedures. Patients were randomized to a 5- or 10-minute groin scrub with Betadine (povidone-iodine). Skin swabs were taken immediately after skin clipping and following routine painting with Betadine. A third swab was taken after the betadine skin scrub. Bacterial colony counts were reported as a number of colony-forming units (CFUs). The primary outcome measure was a quantitative comparison of CFUs in the two arms. Fifty-three patients were randomized to a 5-minute scrub and 48 to a 10-minute scrub. After Betadine painting, CFUs were present in 38% of patients in the 5-minute group (mean, 33.5 CFU) and in 27% of the 10-minute group (mean, 45.4 CFU). Following the surgical scrub, only 7.5% of the 5-minute group and 8.3% of the 10-minute group had a measurable CFU count of greater than or equal to 1, and colony counts were low in both groups (5- minute group: mean, 1.5 CFU; 10-minute group: mean, 2.0 CFU). There was no significant difference in CFUs following a 5- or 10-minute scrub (P = 0.28). The addition of a surgical skin scrub leads to a fourfold reduction in the skin CFU count compared with Betadine painting. However, there is no difference between the antibacterial effects of a 5- and 10-minute scrub. A 5-minute scrub may be sufficient in urologic prosthetic surgery.

COMPARISON OF THE EFFECT OF CALCIUM HYDROXIDE AND THE MODIFIED TRIPLE ANTIBIOTIC PASTE AS INTRACANAL MEDICATION ON THE ELIMINATION OF ENTEROCOCCUS FAECALIS IN RETREATMENT CASES. A RANDOMIZED DOUBLE BLIND CLINICAL TRIAL

Introduction: The present study aimed to evaluate the effect of calcium hydroxide and the modified triple antibiotic paste (MTAP) as intracanal medication on the elimination of the Enterococcus faecalis in retreatment cases. Methods: Sixty patients who attended the outpatient endodontic clinic, faculty of oral and dental medicine, Cairo University were included in this research. Inclusion was limited to patients with symptomatic root canal treated teeth. All teeth underwent non-surgical retreatment. After removal of the gutta percha using protaper rotary retreatment files and irrigation with sodium hypochlorite, the canals were dried and one of the studied medicaments was inserted into the canal in a random sequence. The study was divided into 2 equal groups: Calcium Hydroxide group (CH group n=30) and modified triple antibiotic paste group (MTAP group n=30). Before application of the medicament, canals were sampled using paper points and the colony-forming units grown were counted. After 7 days, the medicaments were removed and the same sampling procedure was repeated. Obturation was then carried out. Results: For both groups, significant decrease in the colony forming units (CFU) of the Enterococcus faecalis resulted after material application. There was no significant difference in CFU between CH group and MTAP group after medication application. Conclusions: MTAP application resulted in decreased CFU of Enterococcus faecalis in nonsurgical retreatment endodontic cases. However there was no statistical significant difference between the use of calcium hydroxide and the modified triple antibiotic paste as intracanal medicament.

Innate Immune Regulation ofSerratia marcescens–Induced Corneal Inflammation and Infection

Serratia marcescens is frequently isolated from lenses of patients with contact lens-associated corneal infiltrates. In the current study, we examined the role of toll-like receptors (TLRs) and interleukin-1 receptor type 1 (IL-1R1) in S. marcescens-induced corneal inflammation and infection. The central corneal epithelium of C57BL/6 and gene knockout mice was abraded, and 1 × 10(7) S. marcescens were added in the presence of a silicone hydrogel contact lens, and we examined corneal inflammation by confocal microscopy and neutrophil enumeration. Viable bacteria were quantified by colony-forming units (CFU). S. marcescens induced neutrophil recruitment to the corneal stroma, and increased corneal thickness and haze in C57BL/6 mice. Conversely, CFU was significantly lower by 48 hours post infection. In contrast, MyD88(-/-), IL-1R(-/-), TLR4(-/-), and TLR4/5(-/-) corneas infected with S. marcescens had significantly increased CFU, indicating impaired clearance. However, there was no significant difference in CFU among C57BL/6, TIRAP(-/-), and TRIF(-/-) mice. Tobramycin-killed S. marcescens induced corneal inflammation in C57BL/6 mice, which was impaired significantly in MD-2(-/-) mice and in C57BL/6 mice pretreated topically with the MD-2 antagonist eritoran tetrasodium. S. marcescens induces corneal inflammation by activation of TLR4/MD-2/MyD88 and the IL-1R1/MyD88 pathways, which are potential therapeutic targets for inhibition of S. marcescens-induced corneal inflammation.

Efficacy of Atmospheric Pressure Plasma as an Antibacterial Agent Against Enterococcus Faecalis in Vitro

Enterococcus faecalis (E. faecalis) is a microorganism that can survive extreme challenges in obturated root canals. The aim of this study was to evaluate the efficacy of a non-thermal atmospheric pressure plasma plume against E. faecalis in vitro. A non-thermal atmospheric pressure plasma jet device which could generate a cold plasma plume carrying a peak current of 300 mA was used. The antibacterial efficacy of this device against E. faecalis and its biofilm under different conditions was detected. The antibacterial efficacy of the plasma against E. faecalis and Staphylococcus aureus (S. aureus) was also evaluated. After plasma treatment, the average diameter of inhibition zone on S. aureus and E. faecalis was 2.62±0.26 cm and 1.06±0.30 cm, respectively (P < 0.05). The diameter was increased with prolongation of the treatment duration. The diameters of inhibition zone of the sealed Petri dishes were larger than those of the uncovered Petri dishes. There was significant difference in colony-forming units between plasma group and control group on E. faecalis biofilm (P < 0.01). The transmission electron microscopy revealed that the ultrastructural changes cytoderm of E. faecalis were observed after treatment for 2 min. It is concluded that the non-thermal atmospheric pressure plasma could serve as an effective adjunct to standard endodontic microbial treatment.

Antimicrobial Efficacy of Two Irrigation Techniques in Tapered and Nontapered Canal Preparations: An In Vitro Study

The aim of this in vitro study was to determine whether irrigation with apical negative pressure was more effective than traditional positive-pressure irrigation in eradicating Enterococcus faecalis from preshaped root canals. Fifty-four extracted mandibular molars were instrumented to produce either a non-tapered or tapered preparation, sterilized, inoculated with E. faecalis for 30 days, and then randomly assigned into the following groups: group 1—non-tapered preparation and negative-pressure irrigation, group 2—non-tapered preparation and positive-pressure irrigation, group 3—tapered preparation and positive-pressure irrigation, and group 4—tapered preparation and negative-pressure irrigation. Mesial canals were sampled before and after final irrigation and samples incubated aerobically for 48 hours at 37°C. Scanning electron microscopic analysis confirmed dense bacterial colonies in the positive control, consistent with biofilm formation. A statistically significant difference was evident when comparing apical negative-pressure irrigation to positive-pressure irrigation (p=0.004). There was no statistically significant difference in colony-forming units (CFUs) between sizes #35 and #45, nor between tapered and non-tapered preparation. The results of this in vitro study showed that apical negative-pressure irrigation has the potential to achieve better microbial control than traditional irrigation delivery systems.

The effects of sucralfate and selective intestinal decontamination on bacterial translocation.

Sucralfate is widely used as a cytoprotective agent in patients with peptic ulcer and other intestinal mucosal damage. In this study, the effects of sucralfate and/or selective intestinal decontamination with gentamycin on bacterial translocation (BT) in rats with experimentally-induced mechanical jaundice were investigated. Seventy-five adult male Wistar albino rats were divided into five groups of 15 each. In all except a sham group, we performed ligation of the common bile duct (CBD) via a vertical laparatomy. After surgery, the rats in group 1 were treated with oral sucralfate (5 mg/kg per day); those in group 2 underwent oral gentamycin therapy (5 mg/kg per day) for 5 days. Group 3 rats were treated with sucralfate and gentamycin for 5 days subsequent to the operation. The rats in group 4 served as controls, and received only 0.9% saline solution. Group 5 was a sham group. After 5 days of surgery, all rats were killed; the mesenteric lymph nodes (MLN), liver, and a segment of terminal ileum were harvested aseptically. The collected tissues were cultured in McCaunkey medium and chocolate agar. For each specimen, the colony-forming units (CFU) were calculated and the percentage of viable translocated micro-organisms was counted. In all rats who had ligation of the CBD, high numbers of bacteria were demonstrated in the liver, MLN, and ileum. In the liver of rats with sucralfate and/or gentamycin treatment, there was a marked reduction in CFU compared to the control group. Similarly, in the MLN measurements of CFU were higher in the control rats than the study groups. In both McCaunkey and chocolate media, the numbers of bacteria in control rats were significantly higher than in the study groups (P < 0.001). However, among the study groups themselves there was no significant difference in CFU in any of the specimens or culture media (P > 0.05). Experimentally-induced mechanical jaundice from ligation of the CBD causes significant BT in rats. Sucralfate and/or gentamycin may reduce the degree of BT from the bowel mucosa. We did not find any difference in protection from BT between sucralfate and gentamycin or both in rats with experimentally-induced mechanical jaundice.

Effect of NaF-, SnF2-, and chlorhexidine-impregnated birch toothpicks on mutans streptococci and pH in approximal dental plaque

The antimicrobial effect of birch toothpicks impregnated with 4% NaF, 8% SnF2, or 2% chlorhexidine was studied both in vitro and in vivo. A non-impregnated toothpick served as a control. In vitro, suspensions of Streptococcus mutans were exposed to the various toothpicks for 20 min and then cultured on blood agar. The results of this susceptibility test revealed the following ranking order with respect to inhibition: chlorhexidine > SnF2 > NaF and non-impregnated; with significant differences in colony-forming units (CFU) between these three groups. In vivo, 12 individuals used the 4 types of toothpick 3 times a day for 5 days in a procedure with a crossover design. Saliva and approximal plaque samples were collected at baseline and on various occasions up to 23 days after the treatment. At the same time, plaque-pH was measured at approximal sites 10 min after rinsing with 10% sucrose. The results of these in vivo experiments revealed lower proportions of mutans streptococci after using all four types of toothpick, but the reduction was significant only after 2 days for the toothpicks impregnated with SnF2 and chlorhexidine (P < 0.05). On the sampling occasions 9 and 23 days after the treatment, the mutans streptococci were more or less back to baseline levels again. In saliva no significant differences in the number of mutans streptococci were found either within or between the four treatments. No significant differences were found regarding decline in the plaque-pH between the NaF-, SnF2-, chlorhexidine-, and non-impregnated toothpicks on any of the sampling occasions.

Quantitative cultures of Candida from mouthwash fluid in HIV-infected patients: a longitudinal study.

The density of Candida colonization in mouthwash fluid of 59 HIV-seropositive patients and 21 controls was determined. No significant difference in colony-forming units was found. No correlation was found between the colonizing density of Candida albicans and the CD4 count among the patients. Twenty-seven of the HIV-seropositive patients were followed for almost 3 years. No difference was found between the number of Candida albicans colony-forming units at the first and second time of sampling. Vaccination with HIV IIIB GP 160 vaccine did not have any influence on the prevalence of Candida albicans.