Thyroid radiation shields: A potential source of intraoperative infection

Introduction

Thyroid radiation shields are often uncovered by the surgical gown and may represent a preventable source of wound contamination. The aims of this study are to define the common pathogens found on thyroid radiation shields and evaluate the effectiveness of a simple cleaning method.

Methods

Samples were obtained from 29 community thyroid shields collected from the operating theatres of 3 teaching hospitals. Each shield was swabbed under strict sterile technique using a separate swab for each of 4 designated zones. After sampling, shields were cleaned with a readily available disinfectant and sampling was repeated after 5 min. All swabs were cultured in ambient air at 37 °C on 5% sheeps blood agar for 48 hrs and subsequent growth was identified by a MALDI-TOF Walkaway mass spectrometer.

Results

Before cleaning, 100% of thyroid shields (29/29) and 68% of shield zones (79/116) grew at least 1 type of bacteria. Coagulase negative staphylococci, including S. epidermidis, S. capitis, S. cohnii, S. haemolyticus and S. hominis, were most commonly isolated. Enterobacteriaceae and S. aureus were also cultured. After cleaning, culturable contamination was reduced by 86.3% and 64.5%, respectively (p < 0.001).

Conclusion

The most common pathogens associated with SSIs can be isolated on thyroid radiation shields. Appropriate cleaning of thyroid shields with readily available disinfectant can significantly reduce the bacterial burden as detectable by culture. Hospitals should facilitate staff education and reinforce their policies on cleaning these shields which may often be overlooked.

A Quality Improvement Approach to Reducing the Caesarean section Surgical Site Infection Rate in a Regional Hospital

Surgical site infection (SSI) rates are used extensively by hospitals as a basis for quality improvement. A 30-day post-discharge SSI programme for Caesarean section operations has been implemented in Our Lady of Lourdes Hospital since 2011. It has been shown that skin antisepsis and antibiotic prophylaxis are key factors in the prevention of SSI. Using quality improvement methodology, an infection prevention bundle was introduced to address these two factors. Skin antisepsis was changed from povidone-iodine to chlorhexidine-alcohol. Compliance with choice of antibiotic prophylaxis increased from 89.6% in 2014 to 98.5% in 2015. Compliance with timing also improved. The SSI rate of 7.5% was the lowest recorded to date, with the majority of SSIs (64%) diagnosed after hospital discharge. The level of variation was also reduced. However, the continued presence of variation and possibility of lower infection rates from the literature imply that further improvements are required.

Incidence of central line related/associated bloodstream infections in an acute hospital

Bloodstream infection related to a central venous catheter in the intensive care unit is a substantial clinical and economic problem. The aim of the study was to examine the incidence of central line related bloodstream infections and central line associated bloodstream infections in Our Lady of Lourdes Hospital, Drogheda, during a six month period, using an active patient based prospective surveillance method. CLRBSI rate in ICU/HDU was 0.93/1000 central line days. There was no CLABSI identified in the studied time period. However, further interventions are needed, particularly with CVC care bundle. Also, the implementation of 2% chlorhexidin in 70% isopropylalcohol use for skin asepsis, which is recommended by the Irish national guidelines, would be beneficial.

A polymerase chain reaction method for the amplification of full-length envelope genes of HIV-1 from DNA samples containing single molecules of HIV-1 provirus

Polymerase chain reaction (PCR) amplification of full-length envelope genes from the human immunodeficiency virus type 1 (HIV-1) directly from uncultured clinical samples is difficult. This paper describes a comparative assessment of the performance of three thermostable polymerases in an HIV-1 full-length envelope gene PCR. The PCR method utilising Expand HiFi polymerase was successful when using DNA samples extracted from a variety of sources including blood, semen and various tissues. This method generated high and specific yields of product from samples containing as little as one copy of HIV-1 proviral DNA. The resulting PCR products were suitable for a variety of downstream analytical methods including DNA sequence analysis.

HIV-1 in semen: determination of proviral and viral titres compared to blood, and quantification of semen leukocyte populations

This study was carried out to determine the relationship between proviral DNA and viral RNA titres in semen compared with blood. In addition, the association between semen leukocyte counts with detection frequency and absolute levels of human immunodeficiency virus type 1 (HIV-1) nucleic acids was also assessed. Paired samples of blood and semen were collected from a cohort of individuals with different blood CD4 cell counts, and whose anti-HIV therapy had not changed in the preceding 3 months. The cell-associated proviral DNA titres and cell-free plasma viral RNA titres were determined using nested primer polymerase chain reaction and NASBAtrade mark, respectively. In addition, leukocyte counts were determined by immunocytochemical and cytochemical staining of a subset of semen samples. HIV-1 proviral DNA was detected in 100% and 47%, and viral RNA was detected in 76% and 63%, of blood and semen samples tested, respectively. HIV-1 proviral DNA and viral RNA titres in blood were higher than in corresponding semen samples, although the difference observed in viral RNA titres was not statistically significant. Proviral DNA and viral RNA titres were correlated between the two body fluids, and within the semen, although some individuals had disparate semen and blood titres or detection rates, indicating genital tract compartmentalisation. In addition, detection of HIV-1 proviral DNA, but not of HIV RNA, in semen was associated with elevated semen leukocyte counts, although this latter finding requires verification in future studies of larger numbers of patients.

Amblyopia and visual acuity in children with Down's syndrome

BACKGROUND/AIMS

Amblyopia in people with Down's syndrome has not been well investigated. This study was designed to determine the prevalence and associated conditions of amblyopia in a group of home reared children with Down's syndrome.

METHODS

All children in the study group underwent an evaluation of visual acuity. In addition, previous ophthalmological records were reviewed, and a subgroup of children was examined. For the purposes of this study, amblyopia was defined quantitatively as a difference of two Snellen acuity lines between eyes or if unilateral central steady maintained (CSM) vision and a clear fixation preference was observed. A high refractive error was defined as a spherical equivalent more than 3 dioptres and astigmatism more than 1.75 dioptres. Anisometropia was defined as a difference of at least 1.5 dioptres of sphere and/or 1.0 dioptre of cylinder between eyes. 68 children with Down's syndrome between the ages of 5 and 19 years were enrolled in the final study group.

RESULTS

Amblyopia was observed in 15 (22%) of 68 patients. An additional 16 (24%) patients had bilateral vision less than 20/50. Strabismus, high refractive errors, and anisometropia were the conditions most commonly associated with decreased vision and amblyopia

CONCLUSION

This study suggests that the prevalence of amblyopia is higher than previously reported. Fully 46% of these children with Down's syndrome had evidence of substantial visual deficits. These patients may be at higher risk for visual impairment and should be carefully examined for ophthalmological problems.

Poor reduction of HIV-1 RNA titres in nucleoside reverse transcriptase inhibitor experienced patients treated with indinavir combination therapy

OBJECTIVES

The long term effectiveness of combination therapy at reducing viral loads in seminal fluid and blood plasma obtained from HIV-1 infected men who had undergone previous antiretroviral therapy was assessed.

METHODS

Samples of semen and blood were obtained from a cohort of 12 nucleoside reverse transcriptase inhibitor experienced men before and during 25-68 weeks of combination therapy, which included the protease inhibitor indinavir. HIV-1 RNA titres present in the cell free blood and seminal plasma samples were determined using the nucleic acid sequence based amplification (NASBA)/Nuclisens assay system.

RESULTS

Viral RNA was detected in 9/12 and 7/12 baseline blood plasma and seminal plasma samples, with median viral titres of 10(4.81) and 10(4.56) per ml, respectively. By the end of the study period the detection rates of HIV RNA in the blood and seminal plasma samples were 5/12 and 2/12, respectively, with the median viral titres below the assay cut off level for both sample types. Of the nine patients who had detectable viral RNA in the baseline sample, only three cleared virus from both compartments by the end of the study.

CONCLUSIONS

These data show that stable reduction of blood and seminal fluid viral titres is not achievable in a significant proportion of nucleoside reverse transcriptase inhibitor experienced men.

TT virus sequence heterogeneity in vivo: evidence for co-infection with multiple genetic types

TT virus (TTV) is a newly described DNA virus of humans that exhibits an unusually high degree of genetic heterogeneity. We have performed extensive analysis of the TTV populations present in samples, taken over a period of 2 to 6 years, from three individuals with persistent TTV infection. TTV DNA titres estimated for sequential samples were found to be quite stable over the entire study period in two patients, but fluctuated considerably in the third. DNA sequence analysis revealed different genetic diversity among TTV populations from samples from the three patients. In one case, absolute sequence homogeneity was observed among samples over a 3 year period. In a second, a limited amount of heterogeneity was found, including one sequence exhibiting G-->A hypermutation. TTV DNA sequences from the third patient exhibited quite remarkable genetic heterogeneity: evidence was found of seven distinct infecting viruses, representing four of the six TTV genotypes that have been described. In addition, minor variants of three of these seven sequences were observed. The heterogeneity of the viral population in this individual declined steadily over a 6 year period. This patient infected with a genetically diverse TTV population had the highest viral DNA titre.

TT virus infection in patients with hepatitis C: frequency, persistence, and sequence heterogeneity

TT virus (TTV) was recently identified in the serum of a patient with hepatitis. The role of TTV in liver disease has not been established. Three polymerase chain reaction (PCR) protocols were used to detect TTV DNA in sera of persons infected with hepatitis C virus (HCV) and in blood donors. Sera from 11.5% of HCV-infected patients and 7.7% of blood donors were positive by protocols 1 or 2. In contrast, 48.7% and 57.7% of sera, respectively, were positive when tested by protocol 3. There was no difference in the severity of hepatitis in persons coinfected with TTV and HCV when compared with those infected with HCV alone, regardless of which TTV PCR protocol was used. TTV DNA persisted in serum samples taken up to 6 years apart in individual patients. Sequence analysis indicated that most viral sequences were distinct between patients, and there was evidence of genetic heterogeneity and viral evolution within individuals.

GBV-C/HGV coinfection in HIV-1-positive men: frequent detection of viral RNA in blood plasma but absence from seminal fluid plasma

Sequential paired samples of blood and seminal fluid were obtained from a cohort of 54 HIV-1-infected homosexual males. The prevalence of GBV-C/HGV RNA in the cell-free fractions of some of these patients was determined using reverse-transcription polymerase chain reaction (RT-PCR). To assess the effects of HIV-1 and HCV infection upon GBV-C/HGV RNA status, blood CD4 cell counts, HCV RNA status, and HIV-1 proviral DNA and viral RNA titres were also determined. GBV-C/HGV RNA was detected in 8/30 (27%) of the blood plasma samples obtained at the start of the study, and was present at a frequency of 14/64 (22%) in all the blood plasma samples tested. By contrast, GBV-C/HGV RNA was not detected in the 26 seminal fluid samples obtained at the start of the study, including 8 samples obtained from patients for which GBV-C/HGV RNA was detected in the corresponding blood sample. Of the samples tested for the presence of both GBV-C/HGV and HCV RNA, there was no evidence of coinfection. Although GBV-C/HGV RNA detection rates were significantly higher in individuals with blood CD4 cell counts greater than 200 cells per microlitre, there were no significant differences in the median blood CD4 cell counts or HIV-1 proviral DNA or viral RNA titres observed between the GBV-C/HGV-positive and -negative individuals. The failure to detect GBV-C/HGV RNA in seminal fluid samples obtained from this cohort would suggest that further studies need to be carried out to determine the roles of sexual transmission and of seminal fluid in GBV-C/HGV infection.

Development and evaluation of a PCR-based immunoassay for the rapid detection of methicillin-resistant Staphylococcus aureus

A multiplex polymerase chain reaction (PCR), involving detection of the mecA and femB genes, was combined with a novel immunoassay system capable of detecting specific PCR products. The resulting PCR-immunoassay was evaluated in comparison with conventional microbiological techniques used in the routine diagnostic laboratory for the rapid identification of methicillin-resistant Staphylococcus aureus (MRSA), either in pure culture or in overnight broth cultures obtained following enrichment of patient screening swabs. Among the 480 purified isolates of staphylococci and 246 enrichment broths examined, only one 'false-negative' result was obtained by PCR, compared with 18 'false-negative' results obtained by conventional methodology and demonstrated by further conventional examination. Five demonstrable 'false-positive' results were obtained by conventional methodology, compared with a possible 10 by the PCR-immunoassay, although it was not certain that these 10 PCR results were true 'false positives' as, by definition, MRSA could not be isolated by conventional methodology. The results indicated that the routine diagnostic laboratory was encountering difficulties in identifying MRSA correctly, and that the conventional microbiological techniques lacked sensitivity. Overall, the PCR technique was more accurate and sensitive than conventional methodology in detecting MRSA, and results were available within 24 h of screening swabs arriving in the laboratory, compared with a minimum of 48-72 h by conventional techniques. The immunoassay system added to the usefulness of the method by allowing the detection of specific PCR products within 5 min of completing the PCR, without the normal additional step of agarose gel electrophoresis.

Semen characteristics in HIV-1 positive men and the effect of semen washing

We have undertaken an analysis of semen from HIV infected men with regard to sperm counts and motility, non-spermatozoal cells, and viral nucleic acid. Regression analysis showed that sperm concentration and motility were positively associated with blood CD4 cell count. By contrast, non-spermatozoal cell concentration (round cells) was inversely related to CD4 count. Extracellular HIV RNA was detected in the majority of semen samples and proviral DNA in a minority. Percoll gradient washing of 12 semen samples yielded six samples containing adequate sperm concentration for analysis. This washing procedure reduced prewash extracellular RNA to below detectable limits in all cases; proviral DNA present in two of the six prewash samples was also reduced to below detectable limits after washing. We conclude that semen washing before artificial insemination may reduce the risk of HIV transmission from an infected man to an uninfected woman. However, further evidence from prospective analyses of such an approach is required.

A randomised comparison between amniotic fluid index and maximum pool depth in the monitoring of post-term pregnancy

OBJECTIVE

To compare the impact of two different ultrasound methods for assessing amniotic fluid volume on the incidence of obstetric interventions in post-term pregnancies.

DESIGN

A prospective randomised controlled trial.

SETTING

Liverpool Women's Hospital.

PARTICIPANTS

Five hundred women with singleton, uncomplicated pregnancies with gestational age > or = 290 days.

INTERVENTIONS

Random allocation to fetal monitoring by either: 1. amniotic fluid index and computerised cardiotocography, or 2. maximum pool depth and computerised cardiotocography.

MAIN OUTCOME MEASURES

Primary: caesarean section. Secondary: the number of abnormal monitoring tests, induction of labour, intrapartum management and neonatal outcome.

RESULTS

The number of abnormal amniotic fluid indices was significantly higher than the number of abnormal maximum pool depths (10% vs 2.4%; OR 4.51, 95% CI 1.82-11.21; P = 0.0008) which resulted in more inductions for abnormal post-term monitoring in the amniotic fluid index group (14.8% vs 8.4%; OR 1.89; 95% CI 1.07-3.33; P = 0.0362) and more intrapartum electronic fetal monitoring (94.4% vs 88.4%; OR 2.21; 95% CI 1.13-4.29; P = 0.0255). There were no other statistically significant differences in outcomes related to labour and delivery, but there was a trend towards more caesarean sections in the amniotic fluid index group (18.8% vs 13.2%), in particular caesarean sections for fetal distress (8% vs 4%). There were no perinatal deaths and no statistically significant differences in perinatal outcome between the two groups.

CONCLUSIONS

Published reference ranges for amniotic fluid index overestimate the number of abnormal results in post-term pregnancies. Their use, when compared with maximum pool depth, is likely to increase the number of obstetric interventions with, as yet, an uncertain impact on perinatal mortality and morbidity. It is possible that antepartum fetal assessment in pregnancies where the risk of adverse perinatal outcome is very low may cause, rather than prevent morbidity.

Comparative in-vitro activity of cefaclor against urinary tract isolates of Escherichia coli

Insusceptibility levels of cefaclor and other commonly prescribed antibiotics were determined for 489 consecutive hospital and community-associated urinary tract isolates of Escherichia coli from the Nottingham area of the UK. Significant resistance (MIC of > or = 8 mg/L) to cefaclor was found to be uncommon in the UK, with insusceptibility percentages as low as 1.5% and 1.4% amongst hospital and community isolates, respectively. When compared with other antimicrobials used commonly for treating urinary tract infection, only ciprofloxacin showed greater activity, though cefaclor showed significantly greater in-vitro activity than cephalexin, ampicillin and trimethoprim. Only seven isolates were insusceptible to cefaclor at a concentration of 8 mg/L. Each of these isolates produced a beta-lactamase, but it is unlikely that beta-lactamase production was the sole reason for insusceptibility since these isolates were also insusceptible to co-amoxiclav. Cefaclor compared extremely well with co-amoxiclav against ampicillin-insusceptible isolates, with none of the pharmacokinetic difficulties and considerations associated with the use of beta-lactam:beta-lactamase inhibitor combinations. Cefaclor appears to be a useful cost-effective alternative to current therapeutic options, particularly for long-term low-dose treatment of recurrent urinary tract infection in those geographical areas where the likelihood of resistance to other possible agents is becoming unacceptably high.

A rapid immunoassay method for the direct detection of PCR products: application to detection of TEM beta-lactamase genes

A rapid immunoassay for the detection of specific PCR products is described in which a positive PCR amplification result is detected, usually in less than 5 min, by applying a few drops of the diluted PCR end-product to a small immunoassay sample device. The method was evaluated in comparison with conventional susceptibility tests and isoelectric focusing (IEF) for the detection of TEM-family beta-lactamase genes in 477 Escherichia coli isolates from urine samples. Of 187 isolates identified as presumptive TEM beta-lactamase producers by conventional methods, 185 generated a positive signal in the PCR immunoassay system. Two further signal-positive isolates were recognised when the PCR was repeated. In addition, one of the 276 ampicillin-susceptible isolates gave a positive signal in repeated PCR-immunoassay experiments despite being ampicillin susceptible and failing to give a TEM-type enzyme band in iso-electric focusing experiments.

Analysis by pulsed-field gel electrophoresis of insertion mutations in the transferrin-binding system of Haemophilus influenzae type b

A mutagenesis system involving the insertion of a non-transposable antibiotic resistance gene cassette was used to generate stable mutations in the chromosome of Haemophilus influenzae type b strain Eagan. The mutations generated were shown by pulsed-field gel electrophoresis (PFGE) to have unique SmaI fingerprint patterns and to be located randomly on the chromosome. Of 700 insertion mutants screened, 29 had stable insertions resulting in constitutive expression of transferrin-binding proteins (TBPs). The high proportion of such mutants indicated that numerous regulatory loci could influence the expression of this phenotype. Five such regulatory mutations were analysed in detail by PFGE and DNA hybridisation and were shown to be located at five different chromosomal loci, although three of the five loci were located on the same 330-kb SmaI fragment of the wild-type strain Eagan chromosome. This fragment also contains several important virulence determinants, including the capb locus, and one of the five constitutive mutants had concomitantly lost the ability to synthesise a type-b capsule. No DNA homology was demonstrated between H. influenzae chromosomal fragments separated by PFGE and DNA probes for the TBPs from Neisseria meningitidis, but the possibility of shared regulatory mechanisms controlling the expression of TBPs in these two species remains to be investigated.

Behavioral changes in culturally disadvantaged children as the result of tutoring

Ss from a disadvantaged population manifested improved classroom behavior as the result of being involved in moderately or highly structured, skill-centered tutoring sessions. This appears to conflict with educational philosophies that advocate unstructured pupil-centered learning situations. However, less structured situations may work best with advantaged and skilled populations, whereas, for unskilled disadvantaged children the structured, skill-centered approach is more successful.