Estimating the cost of antibiotic use on future collateral resistance: a retrospective comparison of cefuroxime versus cefazolin and amoxicillin/clavulanate

Background: Quantitative estimates of collateral resistance induced by antibiotic use are scarce. This study compared the effects of treatment with amoxicillin/clavulanate or cefazolin, compared to cefuroxime, on future resistance to ceftazidime among hospitalized patients. Methods: A retrospective analysis of patients with positive bacterial cultures hospitalized in an Israeli hospital during 2016-2019 was conducted. Patients were restricted to those treated with either amoxicillin/clavulanate, cefazolin, or cefuroxime and re-hospitalized with a positive bacterial culture during the following year. A 1:1 matching was performed for each patient in the amoxicillin/clavulanate and cefazolin groups, to a single patient from the cefuroxime group, yielding 185:185 and 298:298 matched patients. Logistic regression and g-formula (standardization) were used to estimate the odds ratio (OR), risk difference (RD), and number needed to harm (NNH). Results: Cefuroxime induced significantly higher resistance to ceftazidime than amoxicillin/clavulanate or cefazolin: the marginal OR was 1.76) 95%CI 1.16-2.83) compared to amoxicillin/clavulanate, and 1.98 (95%CI 1.41- 2.8) compared to cefazolin; The RD was 0.118 (95%CI 0.031-0.215) compared to amoxicillin/clavulanate, and 0.131 (95%CI 0.058-0.197) compared to cefazolin. We also estimated the NNH: replacing amoxicillin/clavulanate or cefazolin with cefuroxime would yield ceftazidime-resistance in one more patient for every 8.5 (95% CI 4.66-32.14) or 7.6 (95% CI 5.1-17.3) patients re-hospitalized in the following year. Conclusions: Our results indicate that treatment with amoxicillin/clavulanate or cefazolin is preferable to cefuroxime, in terms of future collateral resistance. The results presented here are a first step towards quantitative estimations of the ecological damage caused by different antibiotics.

Metabolic Profiling of Resistant and Susceptible Tobaccos Response Incited by Ralstonia pseudosolanacearum Causing Bacterial Wilt

The causal agent of bacterial wilt, Ralstonia pseudosolanacearum, can cause significant economic losses during tobacco production. Metabolic analyses are a useful tool for the comprehensive identification of plant defense response metabolites. In this study, a gas chromatography-mass spectrometry (GC-MS) approach was used to identify metabolites differences in tobacco xylem sap in response to R. pseudosolanacearum CQPS-1 in two tobacco cultivars: Yunyan87 (susceptible to R. pseudosolanacearum) and K326 (quantitatively resistant). Metabolite profiling 7 days post inoculation with R. pseudosolanacearum identified 88 known compounds, 42 of them enriched and 6 depleted in the susceptible cultivar Yunyan87, while almost no changes occurred in quantitatively resistant cultivar K326. Putrescine was the most enriched compound (12-fold) in infected susceptible tobacco xylem, followed by methyl-alpha-d-glucopyranoside (9-fold) and arabinitol (6-fold). Other sugars, amino acids, and organic acids were also enriched upon infection. Collectively, these metabolites can promote R. pseudosolanacearum growth, as shown by the increased growth of bacterial cultures supplemented with xylem sap from infected tobacco plants. Comparison with previous metabolic data showed that beta-alanine, phenylalanine, and leucine were enriched during bacterial wilt in both tobacco and tomato xylem.

Fungal and mycobacterial cultures should not be routinely obtained for diagnostic work-up of patients with suspected periprosthetic joint infections

Aims Fungal and mycobacterial periprosthetic joint infections (PJI) are rare events. Clinicians are wary of missing these diagnoses, often leading to the routine ordering of fungal and mycobacterial cultures on periprosthetic specimens. Our goal was to examine the utility of these cultures and explore a modern bacterial culture technique using bacterial blood culture bottles (BCBs) as an alternative. Methods We performed a retrospective review of patients diagnosed with hip or knee PJI between 1 January 2010 and 31 December 2019, at the Mayo Clinic in Rochester, Minnesota, USA. We included patients aged 18 years or older who had fungal, mycobacterial, or both cultures performed together with bacterial cultures. Cases with positive fungal or mycobacterial cultures were reviewed using the electronic medical record to classify the microbiological findings as representing true infection or not. Results There were 2,067 episodes of PJI diagnosed within the study period. A total of 3,629 fungal cultures and 2,923 mycobacterial cultures were performed, with at least one of these performed in 56% of episodes (n = 1,157). Test positivity rates of fungal and mycobacterial cultures were 5% (n = 179) and 1.2% (n = 34), respectively. After a comprehensive review, there were 40 true fungal and eight true mycobacterial PJIs. BCB were 90% sensitive in diagnosing true fungal PJI and 100% sensitive in detecting rapidly growing mycobacteria (RGM). Fungal stains were performed in 27 true fungal PJI but were only positive in four episodes (14.8% sensitivity). None of the mycobacterial stains was positive. Conclusion Routine fungal and mycobacterial stains and cultures should not be performed as they have little clinical utility in the diagnosis of PJI and are associated with significant costs. Candida species and RGM are readily recovered using BCB. More research is needed to predict rare non- Candida fungal and slowly growing mycobacterial PJI that warrant specialized cultures. Cite this article: Bone Joint J 2022;104-B(1):53–58.

Evaluation of antimicrobial compounds to inhibit growth of select Gram-positive pathogenic or antimicrobial resistant bacteria in air-exposed silage

Spoiled silages can harbor pathogenic and antimicrobial-resistant microbes. The potential of some antimicrobial additives to inhibit certain pathogenic and antimicrobial-resistant bacteria in air-exposed silage was measured using pure and mixed bacterial cultures. With pure cultures, laurate and monolaurin (5 mg·mL−1) caused decreases (P < 0.05) of 4 to >7 log10 colony-forming units (CFU)·mL−1 in Listeria monocytogenes and Enterococcus faecalis compared to controls. Ten-fold higher amounts of these inhibitors were needed to equivalently decrease staphylococci. 2-Nitropropanol (1 mg·mL−1) decreased (P < 0.05) E. faecalis and L. monocytogenes 2.9–3.8 and 2.4–7.2 log10 CFU·mL−1 after 6 and 24 h incubations, respectively. In air-exposed whole-plant corn silage the inhibitors caused decreases, although not necessarily significant, of 0.7–2.2 log10 CFU·mL−1 in L. monocytogenes, staphylococci and culturable aerobes after 24 h incubation, with modest yet significant (P < 0.05) inhibition (<0.1–0.3 log10 CFU·mL−1) of yeasts and molds. Tests for carry-over effects against ruminal microbes revealed laurate, monolaurin, and 2-nitropropanol inhibited methanogenesis by >50% (P < 0.05) after 24 h incubation and inhibited L. monocytogenes and enterococci. The antimicrobial activities exhibited by these compounds may yield opportunities to optimize their use to rescue spoiled silages.

The Prevalence of Serratia, Stenotrophomonas, Citrobacter and Morganilla Pathogens among Patients with Infectious Diseases at a Governmental Hospital in Riyadh Region

Aim: The present study aimed to explore the prevalence of Serratia, Stenotrophomonas, Citrobacter and Morganilla pathogens among patients with infectious diseases at a governmental hospital in Riyadh Region. Methodology: This study was conducted in a governmental hospital in Riyadh region. Data were collected from the bacterial cultures results that was prepared the laboratory department in the hospital. Results: In the 3 years, the total number of gram negative isolates was 2135. Citrobacter bacteria represented 2.25%, Morganilla represented 1.97%, Stenotrophomonas represented 1.64%, and Serratia represented 1.59% of the gram negative isolates. Conclusion: The present study showed that the rate of Serratia, Stenotrophomonas, Citrobacter, or Morganilla was low. More studies are needed to know the prevalence of these 4 bacteria and to explore the bacterial resistance rate to the available antibiotics.

The pencil eraser swab technique to quantify <i>Cutibacterium acnes</i> on shoulder skin

Introduction: Cutibacterium acnes is the most common cause of postoperative infections in orthopaedic shoulder surgery and is hard to eradicate with current measures. Newer strategies focus on reducing bacterial load on the skin before surgery. Several previous studies have used a large number of both described and undescribed sampling techniques. The purpose of this study was to compare three previously described swab techniques to obtain bacterial cultures: Levine's (L) technique, the Z technique and the pencil eraser swab (PES) technique. Methods: Three consecutive skin swabs were collected from the right shoulder, on 15 healthy male volunteers, using Levine's technique, Z technique and PES technique from each participant. To determine the number of living bacteria, serial dilutions were made, and after culturing for 5 d, viable count (VC) was expressed as CFU/mL (with CFU representing colony-forming unit). Results: The PES technique yielded significantly higher VC than the two others. PES: median 3700 CFU/mL, L: 200 CFU/mL and Z: 220 CFU/mL (p=0.003). There was no significant difference between the methods regarding the number of positive cultures. PES: 14/15, L: 11/15 and Z: 12/15. Conclusions: There is a need to harmonise sampling techniques of C. acnes in order to compare the efficacy of different measures to reduce the bacterial load on the skin before and during surgery. Of the three tested methods, the PES technique is simple and produces the highest bacterial counts.

Ultrafast spectroscopy of C-H vibrations in pathogenic bacteria in 3-μm spectral range

Dynamic optical density spectra were obtained under multipulse excitation of bacterial cultures of S. aureus and P. aeruginosa by 3 μm mid-infrared ultrashort laser pulses, corresponding to the vibrational excitation of the C–H bonds of the bacterial cell. These spectra demonstrated pronounced laser intensity-dependent blue spectral shift, presumably associated with the breaking of hydrogen bonds, which are responsible for the formation of secondary and tertiary protein structures.

Splenectomy for Aseptic Splenic Abscess

Highlight :A 26-year-old woman have sterile aerobic and anaerobic bacterial cultures.Pus and splenic tissue examination revealed no bacterial proliferation, while the surgery revealed a splenic abscess.Abstract:We presented a rare case, a 26-year-old woman have sterile aerobic and anaerobic bacterial cultures. Clinical examination of the patient showed a dense cystic mass in the left upper abdomen. Ultrasonography examination suspected a dermoid cyst. However, MRI examination of the abdomen showed turbid cystic lesions. The surgery revealed a splenic abscess, while pus and splenic tissue examination revealed no bacterial proliferation. Based on the literature, the patient had a good prognosis.

A tick bite patient with fever and meningitis co-infected with Rickettsia raoultii and Tacheng tick virus 1: a case report

Background Increasing numbers of tick-borne pathogens are being discovered, including those that infect humans. However, reports on co-infections caused by two or more tick-borne pathogens are scarce. Case presentation A 38-year-old male farmer was bitten by a hard tick, presented with fever (37.7 °C), severe headache and ejection vomiting. Lumbar puncture was performed in the lateral decubitus. The cerebrospinal fluid (CSF) was clear, and analysis showed severe increased pressure (320 mm H2O), mild leukocytosis (126.0 × 106/L, mononuclear cells accounting for 73%) and elevated total protein concentration (0.92 g/L). Bacterial cultures of CSF and blood were negative. The diagnosis of Rickettsia raoultii and Tacheng tick virus 1 (TcTV-1) co-infection was confirmed by amplifying four rickettsial genetic markers and the partial small (S) RNA segment of TcTV-1 from the patient’s blood. The patient gradually recovered after treatment with levofloxacin and ribavirin. Conclusions This is the first reported co-infection case with fever and meningitis caused by R. raoultii and TcTV-1. It is vital to screen for multiple pathogens in tick-bitten patients, especially in those with severe complex symptoms.

Tattoo-Associated Cutaneous Mycobacterium mageritense Infection: A Case Report and Brief Review of the Literature

There have been increasing reports of tattoo-associated mycobacterial infections in recent years, with a number of outbreaks documented worldwide. This has therefore become a public health concern. Nontuberculous mycobacteria (NTM) are capable of producing skin and soft tissue infections typically via inoculation during surgery, trauma, and cosmetic procedures. We present a case of tattoo-associated cutaneous infection caused by <i>Mycobacterium mageritense</i>, a rare species of rapidly growing NTM. A 25-year-old man developed a rash on his left lower leg 4 weeks after he underwent professional tattooing. A skin swab identified <i>M</i>. <i>mageritense</i> complex. Based on susceptibility testing, a course of oral ciprofloxacin and trimethoprim/sulfamethoxazole was initiated, with significant improvement observed after 5 weeks. We speculate that the mechanism of inoculation was a result of either the artist using nonsterile water to dilute black ink to gray or from use of contaminated prediluted gray ink. The Therapeutic Goods Administration does not have regulatory authority over the sterility of tattoo inks or practices in Australia. Instead, tattoo practices are regulated by local government jurisdictions. Because of the variability seen in clinical presentation and challenges associated with organism identification, a high index of suspicion is required to diagnose mycobacterial infections. Infection caused by NTM should be considered in the differential diagnosis of tattoo-associated dermatological complications, particularly in patients who have chronic lesions, negative bacterial cultures, and fail to respond to standard antibiotic therapy. Mandatory regulations for safe tattoo practices should be considered to prevent outbreaks and ensure public safety.