Prevalence, drivers and surveillance of antibiotic resistance and antibiotic use in rural China: Interdisciplinary study

This study aimed to characterise antibiotic prescribing and dispensing patterns in rural health facilities in China and determine the community prevalence of antibiotic resistance. We investigated patterns and drivers of antibiotic use for common respiratory and urinary tract infections (RTI/UTI) in community settings, examined relationships between presenting symptoms, clinical diagnosis and microbiological results in rural outpatient clinics, and assessed potential for using patient records to monitor antibiotic use. This interdisciplinary mixed methods study included: (i) Observations and exit interviews in eight village clinics and township health centres and 15 retail pharmacies; (ii) Urine, throat swab and sputum samples from patients to identify potential pathogens and test susceptibility; (iii) 103 semi-structured interviews with doctors, patients, pharmacy workers and antibiotic-purchasing customers; (iv) Assessment of completeness and accuracy of electronic patient records through comparison with observational data. 87.9% of 1123 recruited clinic patients were prescribed antibiotics (of which 35.5% contained antibiotic combinations and >40% were for intravenous administration), most of whom had RTIs. Antibiotic prescribing for RTIs was not associated with presence of bacterial pathogens but was correlated with longer duration of infection (OR = 3.33) and presence of sore throat (OR = 1.64). Fever strongly predicted prescription of intravenous antibiotics (OR = 2.87). Resistance rates in bacterial pathogens isolated were low compared with national data. 25.8% of patients reported antibiotics use prior to their clinic visit, but only 56.2% of clinic patients and 53% of pharmacy customers could confirm their prescription or purchase included antibiotics. Diagnostic uncertainty, financial incentives, understanding of antibiotics as anti-inflammatory and limited doctor-patient communication were identified as key drivers of antibiotic use. Completion and accuracy of electronic patient records were highly variable. Prevalence of antibiotic resistance in this rural population is relatively low despite high levels of antibiotic prescribing and self-medication. More systematic use of e-records and in-service training could improve antibiotic surveillance and stewardship in rural facilities. Combining qualitative and observational anthropological methods and concepts with microbiological and epidemiological investigation of antibiotic resistance at both research design and analytic synthesis stages substantially increases the validity of research findings and their utility in informing future intervention development.

Pregnant women's use of e-cigarettes in the UK: a cross-sectional survey

OBJECTIVE

To estimate prevalence of vaping in pregnancy. Compare characteristics and attitudes between exclusive smokers and vapers, and between exclusive vapers and dual users (smoke and vape).

DESIGN

Cross-sectional survey.

SETTING

Hospitals across England and Scotland.

POPULATION

Pregnant women attending antenatal clinics in 2017.

METHODS

Women at 8-24 weeks' gestation completed screening questions about their smoking and vaping. Current or recent ex-smokers and/or vapers completed a full detailed survey about vaping and smoking.

MAIN OUTCOME MEASURES

The prevalence of vaping, characteristics and attitudes of women who vape and/or smoke.

RESULTS

Of 3360 pregnant women who completed screening questions, 515 (15.3%, 95% CI 14.1-16.6) were exclusive smokers, 44 (1.3%, 95% CI 1.0-1.8) exclusive vapers and 118 (3.5%, 95% CI 2.9-4.2) dual users. In total, 867 (25.8%) women completed the full survey; compared with smokers (n = 434), vapers (n = 140) were more likely to hold higher educational qualifications (odds ratio [OR) 1.51, 95% CI 1.01-2.25). Compared with exclusive vapers (n = 33), dual users (n = 107) were younger (OR 0.91 95% CI 0.85-0.98) and less likely to hold high qualifications (OR 0.43, 95% CI 0.20-0.96). Compared with smokers, dual users were more likely to be planning to quit smoking (OR 2.27, 95% CI 1.24-4.18). Compared with smokers, vapers were more likely to think vaping was safer than smoking (78.6% versus 36.4%).

CONCLUSIONS

One in 20 pregnant women report vaping, and most also smoke. Dual users are more motivated towards stopping smoking than smokers. Where women have tried but cannot stop smoking, clinicians could encourage them to consider vaping for smoking cessation.

TWEETABLE EXTRACT

One in 20 women report vaping during pregnancy but of those that do vape, most also smoke, despite having intentions to quit.

In VitroStudies on the Impact of Human Serum on the Antibacterial Effect of Faropenem

The interaction between faropenem and serum in determining antibacterial effect was studied using three target pathogens and two different in vitro methodologies. Strains of Staphylococcus aureus, Streptococcus pneumoniae, capsulate and non capsulate Haemophilus influenzae, all faropenem MIC 0.12 mg/L, were tested in a range of pharmacologically realistic faropenem concentrations with various proportions of serum up to 75%. Using simulated serum bactericidal titres the presence of human serum reduced the activity of faropenem against S. pneumoniae as did heat-treated serum for non-capsulate H. influenzae. Serum on its own was bactericidal against H. influenzae probably due to the presence of complement. The antibacterial effects of combinations of faropenem and serum was assessed in time-kill curves by calculation of the area-under-the bacterial-kill-curve (AUBKC). This was then related to faropenem concentration and the proportion of serum using three-dimensional plots. Serum on its own was mildly inhibitory of the growth of S. aureus, supported improved growth of S. pneumoniae at some proportions and was rapidly bactericidal to H. influenzae, especially the non-capsulate strains. Faropenem had a marked antibacterial effect against all three species in the range 0-2.5 mg/L. Increasing the faropenem concentration from 2.5-10 mg/L produced little or no additional effect. The combination of serum and faropenem had little impact on the antibacterial effect against S. pneumoniae and S. aureus but free drug concentrations were likely to be greater than the MIC in all the combinations used. Against capsulate H. influenzae the effect of serum and faropenem was broadly equivalent while against non-capsulate strains the activity of serum was so great it is difficult to assess the impact of faropenem alone. The interaction between serum and antibiotic in determining antibacterial effect is complex and critically dependent on the proportions of serum and drug concentrations chosen. Three-dimensional plots offer a tool to visualise these complex relationships which may be species specific.

Factors influencing the clinical outcome of methicillin-resistant Staphylococcus aureus bacteraemia

Methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia is associated with high mortality due to a combination of host, pathogen and therapy related factors. This was a retrospective exploratory study to evaluate host, pathogen and therapy related factors influencing the clinical outcome of MRSA bacteraemia in a UK teaching hospital setting. Of the 38 consecutive episodes of MRSA bacteraemia over a 1-year period, 16 of 38 (40%) patients died at 1 month and 21/38 (55%) died at 6 months. Univariate analysis revealed age (p < 0.006), mean serum vancomycin level (p < 0.035), agr group I (p < 0.036) and set4-var2_11 gene (p < 0.036) at 1 month; and age (p < 0.004) and set4-var2_11 gene (p < 0.002) at 6 months as significant factors. However, there was no association between first trough vancomycin concentration and outcome at 1 month. Multivariate survival analysis from time of admission showed, for each one year increase in age, a patient is 1.121 (95% CI 1.006-1.250, p < 0.007) times more likely to die at any particular point in time, and patients with a mean serum vancomycin level of <10 mg/L, the odds ratio of adverse outcome is 16.129 (95% CI 2.398-111.111) compared to patients with a mean serum level >10 mg/L. A variety of host, pathogen, and therapy related factors influence the clinical outcome of MRSA bacteraemia.

Topical ethyl chloride fine spray. Does it have any antimicrobial activity?

AIM

The aim of this study was to assess whether ethyl chloride fine spray (Cryogesic) has antimicrobial activity.

MATERIAL AND METHODS

Blood agar plates supplemented with 5% horse blood were inoculated with five different organisms, coagulase-negative staphylococci (CNS), methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA), Streptococcus pyogenes and Enterococcus faecalis. The plates were assessed for growth inhibition at 24 and 48 h by the microbiologist and compared with the non-sprayed control plates.

RESULTS

The model showed a highly significant (p<0.0001) reduction in bacterial count for the plates treated with fine ethyl chloride spray. The estimate of the percentage of bacteria remaining after spraying with ethyl chloride was 42.7%, with a 95% confidence interval of 35.9-50.9%. There was no evidence that the effect of ethyl chloride fine spray was different for the different organisms (p=0.49).

CONCLUSION

The use of ethyl chloride shows bacterial count reduction but the clinical implication of this needs to be determined. The authors postulate that any statistically significant reduction can only be helpful in reducing the infection rates. This coupled with the already proven local anaesthetic effects of ethyl chloride will make it an important tool for procedures like arthrocentesis and venepunctures.

Bacterial contamination of surgical gloves by water droplets spilt after scrubbing

Wound infection and deep sepsis can have disastrous consequences, particularly in orthopaedic surgery. Strict protocols, ultra-clean air, prophylactic antibiotics, and impervious gowns and drapes, have all been shown to diminish wound infection. However it remains a common and significant problem. The water droplets spilt from the surgeons hands after meticulous scrubbing with povidone iodine were cultured. The permeability of the surgical glove packaging to Gram-positive bacteria was also investigated. The water droplets from the surgeon's arms contained environmental and potentially pathogenic bacteria including a micrococcus, a coliform and coagulase-negative staphylococci. The paper packaging for the range of sterile surgical gloves tested was discovered to be permeable to Gram-positive bacteria. In conclusion accidental water droplet contamination of surgical gloves is a potential source of infection. Alternative recommendations are made.

Bacterial strike-through of re-usable surgical drapes: the effect of different wetting agents

Wound contamination and the resultant postoperative infection is a major problem in all forms of surgery. Air contamination, gloves, surgical instruments and drapes have all been investigated as sources of wound contamination. We investigated the effect of different wetting agents on strike-through rate of bacteria through re-usable polyester/cotton surgical drapes using a newly described method. Within 30 min bacterial strike-through of dry surgical drapes occurs. Wetting drapes with blood or normal saline enhances the strike-through rate of bacteria. Wetting drapes with iodine or chlorhexidine diminishes, but does not stop, bacterial strike-through. The use of re-usable polyester/cotton drapes is a potential source of wound contamination especially when wetted with blood or normal saline.

In vitro models, in vivo models, and pharmacokinetics: what can we learn from in vitro models?

In vitro pharmacokinetic models of infection can make an important contribution to the study of the pharmacodynamic properties of an antibacterial agent. In conjunction with animal and human pharmacodynamic evaluations, they provide data to allow for the optimization of drug dosing regimens. In vitro models can be used simply to describe the effect of a drug on a bacterial population as well as to provide data for more-analytical studies, including hypothesis testing. Analytical study designs provide information on the pharmacodynamic parameter best related to the chosen outcome, as well as its magnitude. Factors such as the characteristics of the model (method of drug removal, inoculum density, and growth phase), doses simulated, species and susceptibility range of bacteria, and methods and analytical tools used to measure antibacterial effect will have an effect on the conclusions drawn. In vitro models have an important future role in ensuring antibiotic efficacy and in reducing the risks of resistance.

The passage of bacteria through surgical drapes

The passage of bacteria through surgical drapes is a potential cause of wound infection. Previous studies have shown that liquids and human albumin penetrate certain types of drapes. We studied the passage of bacteria through seven different types of surgical drape and an operating tray. Bacteria easily penetrated all the woven re-usable fabrics within 30 min. The disposable non-woven drapes proved to be impermeable, as did the operating tray. We recommend the use of non-woven disposable drapes or woven drapes with an impermeable operating tray in all surgical cases.

Assessment of different antibacterial effect measures used in in vitro models of infection and subsequent use in pharmacodynamic correlations for moxifloxacin

A dilutional culture in vitro pharmacodynamic model of infection was used to assess the best measure of antibacterial effect for moxifloxacin at simulated human doses of 400 mg 24 hourly for 48 h. This was then related to two pharmacodynamic parameters, the drug area under curve: MIC ratio (AUC/MIC) and the length of time that the drug concentration remained above the MIC of the bacterium (T > MIC). Twenty-one bacterial strains (Streptococcus pneumoniae n = 6; Haemophilus influenzae n = 6; Moraxella catarrhalis n = 3; beta-haemolytic streptococci n = 3; Staphylococcus aureus n = 3; MIC range 0.06-3.6 mg/L) were tested in 69 individual simulations. The measures or parameters of antibacterial effect considered were log change in viable count in the initial inoculum at 12 h (triangle up12), 24 h (triangle up24), 36 h (triangle up36), 48 h (triangle up48), maximum reduction in count (triangle up(max)); time for bacterial counts to reduce by 100-fold from the initial density (T99) or 1,000-fold (T99.9); and area under the bacterial kill curve from 0 to 24 h (AUBKC(24)) or from 0 to 48 h (AUBKC(48)). triangle up12, triangle up24, triangle up36, triangle up48, triangle up(max), T99, T99.9 did not vary over the complete range of MICs; at high MICs, especially with Gram-positive bacteria the T99 and T99.9 values were >48 h while at low MICs, especially with Gram-negative bacteria, bacterial counts were reduced below the limit of detection with triangle up12, triangle up24, triangle up36, triangle up48 and triangle up(max) exceeding >6.5 log reduction. AUBKC(24) and AUBKC(48) varied more completely over the range of MICs and more importantly had the best within-strain reproducibility (median percentage coefficient of variation <15%). The relationship between the transformed AUBKC(24) and AUC/MIC could be described by a sigmoid Emax model but the relationship with T > MIC could not. Use of weighted least squares regression to examine the combined effect of AUC/MIC and T > MIC on AUBKC(24) indicated that AUC/MIC provided a good fit to the data (r(2) = 0.94) and adding T > MIC did not improve the model fit. Cox proportional hazards regression indicated that AUC/MIC was predictive of T99 and in a multivariate model although AUC/MIC predicted outcome after fitting AUC/MIC, T > MIC was not significant. AUBKC was thus shown to be the optimum measure of antibacterial effect to use in pharmacodynamic studies of moxifloxacin and AUC/MIC the best predictor of antibacterial effect as measured by AUBKC(24) or T99. These results are in good agreement with animal data on moxifloxacin pharmacodynamics and human data for some other fluoroquinolones.

External quality assessment of the serum bactericidal test: results of a methodology/interpretation questionnaire

Two hundred microbiology laboratories in the UK took part in two separate experimental external quality assessment distributions related to the serum bactericidal test (SBT). In the first, Staphylococcus aureus NCTC 6571 (vancomycin MIC 1 mg/L), was tested against a human serum containing vancomycin 38 mg/L plus gentamicin 0.5 mg/L. In the second, Streptococcus oralis PAJ 112/4183 (penicillin MBC < or = 0.03 mg/L) and Streptococcus sanguis PAJ 107/4184 (penicillin MBC = 128 mg/L) were tested against human serum containing penicillin 15 mg/L. Respondents returned their laboratory results and a questionnaire on clinical interpretation and technical aspects. Most laboratories (194/199, 97.5%) recommend the use of the SBT in the management of infective endocarditis but only 48 (25.2%) often or always change therapy on the basis of the result. A wide range of interpretative criteria, definitions of bactericidal endpoints and methodologies are used. Performance in the first distribution was acceptable for 75% of laboratories but in the second only 34% could identify penicillin tolerance; 34 respondents reported an SBT result of < or = 2 for the tolerant strain, 81 laboratories reported one of > or = 16. Technical factors related to acceptable performance were: sonication of broth before counting the inoculum; knowing the inoculum size in cfu/mL; use of a 4-8 h broth culture to make the inoculum; incubation of recovery plates for > 36 h; use of a calibrated pipette to sample for surviving bacteria; use of measured volumes to add the inoculum. Use of uncalibrated pipettes or standard loops to recover survivors was related to poor performance. Microbiology departments in the UK should review the clinical need to perform the SBT in the light of their local circumstances and if they elect to continue to offer this test, revise their methodologies which could be producing misleading results when testing alpha-haemolytic streptococci.

Typing of Listeria monocytogenes by random amplified polymorphic DNA (RAPD) analysis

The aim of the study was to determine the effectiveness of random amplified polymorphic DNA analysis in typing Listeria monocytogenes from human infections. Twenty-five L. monocytogenes serogroup 1/2 and 70 serogroup 4 including 14 serovar 4b(x) were typed by RAPD-PCR analysis. Six primers were used to type each L. monocytogenes isolate and the DNA amplification performed with supertaq DNA polymerase in a Hybaid Thermal Reactor. Each bacterial strain was analysed separately with all primers and the profiles were judged by eye and designated to a group by comparison to other strains. Bands were classified as major or minor. Based on analysis of major band patterns, the 25 serogroup 1/2 isolates gave rise to 12 different groups. The groups only contained serovar 1/2a or 1/2b with a single exception. Using minor bands all isolates could be distinguished. All the serogroup 4 isolates gave the same major band patterns. The 14 serovar 4b(x) isolates which were epidemiologically related gave identical profiles with the exception of one isolate. Of the remaining strains, 41 produced individual patterns on minor band analysis. RAPD analysis with multiple primers is low cost, discriminatory and is most ideally suited to testing small (< 50) numbers of strains. We have shown that serogroup 1/2 L. monocytogenes strains are a more diverse group than serovar 4b strains and RAPD-PCR will provide a technique of considerable value in typing L. monocytogenes in the future.

The occurrence and seasonal changes in the isolation of Listeria spp. in shop bought food stuffs, human faeces, sewage and soil from urban sources

Eight hundred and twenty-two shop-bought food specimens, 136 soil and 692 faecal specimens were cultured for Listeria spp. in a regular, year round survey. 19.7% (162/822) of the foods, 93.9% (108/115) of the sewage, 14.7% (20/136) soils and 1% (7/692) of faeces yielded Listeria spp. with 10.5% foods, 60.0% sewage, 0.7% soils and 0.6% faeces containing L. monocytogenes. No seasonal variation was noted in isolates from either sewage or foods, with L. monocytogenes and L. innocua being the commonest species in both L. ivanovii when isolated from foods was strongly associated with mutton. Poultry was most likely to contain L. monocytogenes (65.6%, 21/32) and in the greatest numbers. A high percentage of beef (34.6%, 9/26), lamb (40%, 8/20), pork (28.1%, 9/32) and sausages (34.7%, 8/23) also contained L. monocytogenes. L. monocytogenes was rarely isolated from paté (1/40) or soft cheeses (1/251), both of which have been involved with foodborne listeriosis outbreak in the UK. Listeria spp. were commonest in faeces and soils in July to September but the predominant species isolated were different with L. monocytogenes and L. innocua the commonest from faeces and L. ivanovii and L. seeligeri the most common from soil.