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Background: Results of IBCSG-23-01-trial which included breast cancer patients with involved sentinel nodes (SN) by isolated-tumor-cells or micro-metastases supported the non-inferiority of completion axillary-lymph-node-dissection (cALND) omission. However, current data are considered insufficient to avoid cALND for all patients with SN-micro-metastases., Methods: To investigate the impact of cALND omission on disease-free-survival (DFS) and overall survival (OS), we analyzed a cohort of 1421 patients <75 years old with SN-micro-metastases who underwent breast conservative surgery (BCS). We used inverse probability of treatment weighting (IPTW) to obtain adjusted Kaplan-Meier estimators representing the experience in the analysis cohort, based on whether all or none had been subject to cALND omission., Results: Weighted log-rank tests comparing adjusted Kaplan-Meier survival curves showed significant differences in OS (p-value = 0.002) and borderline significant differences in DFS (p-value = 0.090) between cALND omission versus cALND. Cox's regression using stabilized IPTW evidenced an average increase in the risk of death associated with cALND omission (HR = 2.77, CI95% = 1.36-5.66). Subgroup analyses suggest that the rates of recurrence and death associated with cALND omission increase substantially after a large period of time in the half sample of women less likely to miss cALND., Conclusions: Using IPTW to estimate the causal treatment effect of cALND in a large retrospective cohort, we concluded cALND omission is associated with an increased risk of recurrence and death in women of <75 years old treated by BCS in the absence of a large consensus in favor of omitting cALND. These results are particularly contributive for patients treated by BCS where cALND omission rates increase over time., (© 2022 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.)

Based on results of clinical trials, completion ALND (cALND) is frequently not performed for patients with breast conservation therapy and one or two involved sentinel nodes (SN) by micro- or macro-metastases. However, there were limitations despite a conclusion of non-inferiority for cALND omission. No trial had included patients with SN macro-metastases and total mastectomy or with >2 SN macro-metastases. The aim of the study was too analyze treatment delivered and pathologic results of patients included in SERC trial. SERC trial is a multicenter randomized non-inferiority phase-3 trial comparing no cALND with cALND in cT0-1-2, cN0 patients with SN ITC (isolated tumor cells) or micro-metastases or macro-metastases, mastectomy or breast conservative surgery. We randomized 1855 patients, 929 to receive cALND and 926 SLNB alone. No significant differences in patient's and tumor characteristics, type of surgery, and adjuvant chemotherapy (AC) were observed between the two arms. Rates of involved SN nodes by ITC, micro-metastases, and macro-metastases were 5.91%, 28.12%, and 65.97%, respectively, without significant difference between two arms for all criteria. In multivariate analysis, two factors were associated with higher positive non-SN rate: no AC versus AC administered after ALND (OR = 3.32, p < 0.0001) and >2 involved SN versus ≤2 (OR = 3.45, p = 0.0258). Crude rates of positive NSN were 17.62% (74/420) and 26.45% (73/276) for patient's eligible and non-eligible to ACOSOG-Z0011 trial. No significant differences in patient's and tumor characteristics and treatment delivered were observed between the two arms. Higher positive-NSN rate was observed for patients with AC performed after ALND (17.65% for SN micro-metastases, 35.22% for SN macro-metastases) in comparison with AC administered before ALND., (© 2021. The Author(s).)

The study of anatomy has played a large part in the progress of scientific observation throughout the centuries and was pivotal in elevating anatomy from the magical thinking of the Hippocrates era and freeing it from subservience to medicine which was all-powerful in the past. Anatomy theaters appeared in Northern Italy in the 14th century and developed in Western Europe from the early 16th century to the beginning of the 19th century. Anatomy theaters lived their golden age in France during the 18th century when the Royal Academy of Surgery (Académieroyaledechirurgie) was created in 1743. These theaters were open to the public, and therefore offered the double vocation of teaching and public entertainment: they were used to teach anatomy and surgery to students and surgeons and offered distraction for the well-informed public that was fascinated by death, ever-present and familiar to all. Anatomical dissection accomplished a double ritual: the "profane" ritual of valorization of scientific knowledge and the "sacred" ritual, where mankind, obsessed with death, respected the human body considered as a divine image. Anatomy theaters declined as they became overshadowed by progress in anatomical teaching using well-illustrated works in well-equipped medical schools while exhibition of anatomic oddities for public amusement was relegated to fairs and circus sideshows. Nonetheless they opened the way to modern anatomo-clinical methods and surgery., (Copyright © 2020. Published by Elsevier Masson SAS.)

Purpose: The prevalence of pelvic organ prolapse (POP) is increasing. The number of women aged 70-80 years requiring surgical management for POP is also increasing. The purpose of this study was to compare the complications associated with three pelvic organ prolapse repair methods, sacrocolpopexy (SCP), native tissue repair (NTR), and vaginal mesh repair (VMR), in women aged 70-80 years., Methods: We performed a multi-institutional retrospective analysis of 213 women who underwent POP surgical repairs between December 2012 and December 2017. Treatment-related complications were classified using the ClavienDindo grading system and compared among the three groups. Perioperative data, anatomical success rates, patient satisfaction, and postoperative complication data were collected during the follow-up period, which lasted up to 12 months., Results: Of 213 patients, 70 (33%) underwent SCP, 85 (40%) underwent NTR, and 58 (28%) underwent VMR. By postoperative day 30, the all-inclusive complication rate was lower in the SCP group than in the NTR or VMR group; however, there was no between-group difference in complication grade. The VMR group underwent fewer concomitant hysterectomies than the other groups, and operative time was the longest for SCP. Overall, recovery time, anatomical success rate, and patient satisfaction were comparable for all three repairs., Conclusions: All three surgical techniques were equivalent in patient satisfaction, anatomical success rate, and complication rate. SCP should be recommended to elderly women who meet criteria for prolonged general anesthesia, as it was associated with fewer perioperative complications than NTR and VMR.

Background: A strong correlation between breast cancer (BC) molecular subtypes and axillary status has been shown. It would be useful to predict the probability of lymph node (LN) positivity., Objective: To develop the performance of multivariable models to predict LN metastases, including nomograms derived from logistic regression with clinical, pathologic variables provided by tumor surgical results or only by biopsy., Methods: A retrospective cohort was randomly divided into two separate patient sets: a training set and a validation set. In the training set, we used multivariable logistic regression techniques to build different predictive nomograms for the risk of developing LN metastases. The discrimination ability and calibration accuracy of the resulting nomograms were evaluated on the training and validation set., Results: Consecutive sample of 12,572 early BC patients with sentinel node biopsies and no neoadjuvant therapy. In our predictive macro metastases LN model, the areas under curve (AUC) values were 0.780 and 0.717 respectively for pathologic and pre-operative model, with a good calibration, and results with validation data set were similar: AUC respectively of 0.796 and 0.725. Among the list of candidate's regression variables, on the training set we identified age, tumor size, LVI, and molecular subtype as statistically significant factors for predicting the risk of LN metastases., Conclusions: Several nomograms were reported to predict risk of SLN involvement and NSN involvement. We propose a new calculation model to assess this risk of positive LN with similar performance which could be useful to choose management strategies, to avoid axillary LN staging or to propose ALND for patients with high level probability of major axillary LN involvement but also to propose immediate breast reconstruction when post mastectomy radiotherapy is not required for patients without LN macro metastasis.

Background: Three randomized trials have concluded at non inferiority of omission of complementary axillary lymph node dissection (cALND) for patients with involved sentinel node (SN). However, we can outline strong limitations of these trials to validate this attitude with a high scientific level. We designed the SERC randomized trial ( ClinicalTrials.gov , number NCT01717131) to compare outcomes in patients with SN involvement treated with ALND or no further axillary treatment. The aim of this study was to analyze results of the first 1000 patients included., Methods: SERC trial is a multicenter non-inferiority phase 3 trial. Multivariate logistic regression analysis was used to identify independent factors associated with adjuvant chemotherapy administration and non-sentinel node (NSN) involvement., Results: Of the 963 patients included in the analysis set, 478 were randomized to receive cALND and 485 SLNB alone. All patient demographics and tumor characteristics were balanced between the two arms. SN ITC was present in 6.3% patients (57/903), micro metastases in 33.0% (298), macro metastases in 60.7% (548) and 289 (34.2%) were non eligible to Z0011 trial criteria. Whole breast or chest wall irradiation was delivered in 95.9% (896/934) of patients, adjuvant chemotherapy in 69.5% (644/926), endocrine therapy in 89.6% (673/751) and the proportions were similar in the two arms. The overall rate of positive NSN was 19% (84/442) for patients with cALND. Crude rates of positive NSN according to SN status were 4.5% for ITC (1/22), 9.5% for micro metastases (13/137), 23.9% for macro metastases (61/255) and were respectively 29.36% (64/218), 9.33% (7/75) and 7.94% (10/126) when chemotherapy was administered after cALND, before cALND and for patients without chemotherapy., Conclusion: The main objective of SERC trial is to demonstrate non inferiority of cALND omission. A strong interaction between timing of cALND and chemotherapy with positive NSN rate was observed., Trial Registration: This study is registered with ClinicalTrials.gov , number NCT01717131 October 19, 2012.

Introduction and hypothesis: Descending Perineum Syndrome (DPS) is a coloproctologic disease and the best treatment for it is yet to be defined. DPS is frequently associated with pelvic organ prolapse (POP) and it is reasonable to postulate, that treatment of POP will also have an impact on DPS. We aimed to evaluate the subjective satisfaction and improvement of DPS for patients who have undergone a sacral colpoperineopexy associated with retrorectal mesh for concomitant POP. Methods: This retrospective cohort study, conducted between February 2010 and May 2016 included all women who had undergone surgery to treat POP and DPS. Improvement of POP was assessed clinically and subjective satisfaction was assessed with a survey. Results: Among the 37 operated patients, 31 responded to the questionnaire and 77.4% were satisfied with this surgical procedure. 94.6% were objectively cured for POP. There was a 60% improvement rate for constipation, 63.5 and 68% were cured or improved for ODS and the need for digital maneuvers respectively. Conclusion: Sacral colpoperineopexy associated with retrorectal dorsal mesh appears to objectively and subjectively improve POP associated with DPS.

Biofilm has become a major topic of interest in medical, food, industrial, and environmental bacteriology. To be relevant, investigation of biofilm behavior requires effective and reliable techniques. We present herein a simple and robust method, adapted from the microplate technique, in which steam is used as a soft washing method to preserve biofilm integrity and to improve reproducibility of biofilm quantification. The kinetics of steam washing indicated that the method is adapted to remove both planktonic bacteria and excess crystal violet (CV) staining for S. aureus, S. epidermidis, S. carnosus, P. aeruginosa, and E. coli biofilm. Confocal laser scanning microscopy confirmed that steam washing preserved the integrity of the biofilm better than pipette-based washing. We also investigated the measurement of the turbidity of biofilm resuspended in phosphate-buffered saline (PBS) as an alternative to staining with CV. This approach allows the discrimination of biofilm producer strains from non-biofilm producer strains in a way similar to CV staining, and subsequently permits quantification of viable bacteria present in biofilm by culture enumeration from the same well. Biofilm quantification using steam washing and PBS turbidity reduced the technical time needed, and data were highly reproducible.

Background: Sentinel lymph node biopsy (SLNB) remains under discussion for large size tumors. The aim of this work has been to study the false negative rate (FNR) of SLNB for large tumors and predictive factors of false negative (FN)., Materials and Methods: A study of a multicentric cohort, involved patients presenting N0 breast cancer with a SLNB eventually completed by complementary axillary lymph node dissection (cALND). The main criteria were the FNR and the predictive factors of FN., Results: 12.415 patients were included: 748 with tumors ≥30 mm, 1101 with tumors >20 and < 30 mm and 10.566 with tumors ≤20 mm, with a cALND respectively for 501 patients (67%), 523 (62.1%) and 2775 (26.3%). The FNR were respectively: 3.05% (IC95%: 1.3-4.8) for tumors ≥30 mm*, 3.5% (1.8-5.2) for tumors >20 and < 30 mm*, 1.8% (1-2.4) for tumors ≤20 mm (p < 0.05) (*Not significant). At multivariate analysis, SN number harvested ≤2 (OR:2.0, p = 0.023) and tumor size >20 and < 30 mm (OR:2.07, p = 0.017) were significant predictive factors of FN, without significant value for tumor size ≥30 mm (OR:1.83, p = 0.073)., Conclusion: The FNR of SLNB was not higher amongst large size tumors compared to tumors of a smaller size. These results support the validation of SNLB for tumors up to 50 mm., (Copyright © 2017. Published by Elsevier Ltd.)

Background: To estimate the proportion of elderly patients (>70 years) with breast cancer eligible for an Exclusive IntraOperative RadioTherapy (E-IORT) and to evaluate their local recurrence-free survival rate., Methods: This retrospective study examining two cohorts focuses on patients over 70 years old: a multi-centric cohort of 1411 elderly patients and a mono-centric cohort of 592 elderly patients. All patients underwent conservative surgery followed by external radiotherapy for T0-T3 N0-N1 invasive breast cancer, between 1980 and 2008., Results: Within each cohort two groups were identified according to the inclusion criteria of the RIOP trial (R group) and TARGIT E study (T group). Each group was divided into two sub-groups, patients eligible (E) or non-eligible (nE) for IORT. The population of patients that were eligible in the TARGIT E study but not in the RIOP trial were also studied in both cohorts. The proportion of patients eligible for IORT was calculated, according to the eligibility criteria of each study. A comparison of the 5-year local or locoregional recurrence-free survival rate between eligible vs non-eligible patients was made. In both cohorts, the proportion of patients eligible according to the RIOP trial's eligibility criteria was 35.4 and 19.3%, and according to the TARGIT E study criteria was 60.9 and 45.3%. The 5-year locoregional recurrence-free survival rate was not significantly different between RE and RnE groups, TE and TnE groups. In both cohorts RE and (TE-RE) groups were not significantly different., Conclusions: Our results encourage further necessary studies to define and to extend the eligibility criteria for per operative exclusive radiotherapy.

Background: Triple-negative breast cancers (TNBCs) are the most deadly form of breast cancer (BC) subtypes. Axillary lymph node involvement (ALNI) has been described to be prognostic in BC taken as a whole, but its prognostic value in each subtype is unclear. We explored the prognostic impact of ALNI and especially of small size axillary metastases in early TNBCs., Methods: We analysed in this multicentre study all patients treated for early TNBC in 12 French cancer centres. We explored the correlation between clinicopathological data and ALNI, with a specific focus on the dichotomisation between macrometastases and occult metastases, which is defined as the presence of isolated tumour cells or micrometastases. The prognostic value of ALNI both in terms of disease-free survival (DFS) and overall survival (OS) was also explored., Results: We included 1237 TNBC patients. Five-year DFS and OS were 83.7% and 88.5%, respectively. The identified independent prognostic features for DFS were tumour size >20 mm (hazard ratio (HR)=1.86; 95% CI: 1.11-3.10, P=0.018), lymphovascular invasion (HR=1.69; 95% CI: 1.21-2.34, P=0.002) and ALNI both in case of macrometastases (HR=1.97; 95% CI: 1.38-2.81, P<0.0001) and occult metastases (HR=1.72; 95% CI: 1.1-2.71, P=0.019). DFS and OS were similar between tumours with occult metastases and macrometastases. Tumours presenting at least two pejorative features (out of ALNI, lymphovascular invasion and large tumour size) displayed a significantly poorer DFS in both the training set and validation set, independently of chemotherapy administration. Tumours with no more than one of the above-cited pejorative features had a 5-year OS of ⩾90% vs 70% for other cases (P<0.0001)., Conclusions: Axillary lymph node involvement is a key prognostic feature for early TNBC when isolated tumour cells were identified in lymph nodes. This impact is independent of chemotherapy use.

In order to study the interactions between Escherichia coli DNA gyrase and the gyrase interacting protein QnrB in vivo, we constructed a gyrB-gyrA fusion and validated its ability to correct the temperature-sensitive growth of gyrA and gyrB mutants. Like wild-type gyrA, the gyrB-gyrA fusion complemented a quinolone-resistant gyrA mutant to increase susceptibility. It functioned as an active type II topoisomerase, catalyzed negative supercoiling of DNA, was inhibited by quinolone, and was protected by QnrB., (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)

Purpose: Persistent urinary retention (UR) is a complication of 3.5-14.3% of patients having undergone deep pelvic endometriosis (DPE) surgery of posterior compartment, and it is prone to persist. The purpose of this study is to identify surgical procedures and clinical circumstances associated with persistent UR, and consider its treatment., Methods: We undertook a multi-center retrospective study studying medical records of patients who had surgery for DPE between January 2005 and December 2012. Patients who suffered from UR defined as a post-void residual (PVR) volume >100 mL needing intermittent self-catheterizations more than 30 days after surgery were included. Preoperative data (functional complaints, clinical examination, imaging, medical treatment) were recorded. Types of surgery and detailed postoperative urinary symptoms were noted., Results: 881 patients had surgery for DPE and 16 patients were included (1.8%). In 93.8% of cases, a lesion of posterior compartment was clinically significant. Mean lesion size was 28.8 ± 7.3 mm. Colorectal resection and colpectomy were necessary in 93.8 and 87.5% of cases, respectively. Loss of bladder sensation and straining during urination were the two most common post-operative symptoms. 11 patients still required self-catheterization up to 1 year after the intervention., Conclusions: Patients with increased risks of UR present with a symptomatic and clinically palpable deep pelvic endometriotic lesion of the posterior compartment. Treatment implies surgery with colorectal resection. Bilateral resection of utero-sacral ligaments and posterior colpectomy tend to increase that risk. Complications due to PVR volume and straining during urination may be prevented by self-catheterization.

Background: We wished to estimate the proportion of patients with breast cancer eligible for an exclusive targeted intraoperative radiotherapy (TARGIT) and to evaluate their survival without local recurrence., Methods: We undertook a retrospective study examining two cohorts. The first cohort was multicentric (G3S) and contained 7580 patients. The second cohort was monocentric (cohort 2) comprising 4445 patients. All patients underwent conservative surgery followed by external radiotherapy for invasive breast cancer (T0-T3, N0-N1) between 1980 and 2005. Within each cohort, two groups were isolated according to the inclusion criteria of the TARGIT A study (T group) and RIOP trial (R group).In the multicentric cohort (G3S) eligible patients for TARGIT A and RIOP trials were T1E and R1E subgroups, respectively. In cohort number 2, the corresponding subgroups were T2E and R2E. Similarly, non-eligible patients were T1nE, R1nE and T2nE, and R2nE.The eligible groups in the TARGIT A study that were not eligible in the RIOP trial (TE-RE) were also studied. The proportion of patients eligible for TARGIT was calculated according to the criteria of each study. A comparison was made of the 5-year survival without local or locoregional recurrence between the TE versus TnE, RE versus RnE, and RE versus (TE-RE) groups., Results: In G3S and cohort 2, the proportion of patients eligible for TARGIT was, respectively, 53.2% and 33.9% according the criteria of the TARGIT A study, and 21% and 8% according the criteria of the RIOP trial. Survival without five-year locoregional recurrence was significantly different between T1E and T1nE groups (97.6% versus 97% [log rank=0.009]), R1E and R1nE groups (98% versus 97.1% [log rank=0.011]), T2E and T2nE groups (96.6% versus 93.1% [log rank<0. 0001]) and R2E and R2nE groups (98.6% versus 94% [log rank=0.001]). In both cohorts, no significant difference was found between RE and (TE-RE) groups., Conclusions: Almost 50% of T0-2 N0 patients could be eligible for TARGIT.

To define the prognostic value of isolated tumor cells (ITC), micrometastases (pN1mi) and macrometastases in early stage breast cancer (ESBC). We conducted a retrospective multicenter cohort study at 13 French sites. All the eligible patients who underwent SLNB from January 1999 to December 2008 were identified, and appropriate data were extracted from medical records and analyzed. Among 8001 patients, including 70% node-negative (n = 5588), 4% ITC (n = 305), 10% pN1mi (n = 794) and 16% macrometastases (n = 1314) with a median follow-up of 61.3 months, overall survival (OS) and recurrence-free survival (RFS) rates at 84 months were not statistically different in ITC or pN1mi compared to tumor-free nodes. Axillary recurrence (AR) was significantly more frequent in ITC (1.7%) and pN1mi (1.5%) compared to negative nodes (0.6%). Survival and AR rates of single macrometastases were not different from those of ITC or pN1mi. In case of 2 macrometastases or more, survival rates decreased and recurrence rates increased significantly. Micrometastases and ITC do not have a negative prognostic value. Single macrometastases might have an intermediate prognostic value while 2 macrometastases or more are associated with poorer prognosis., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The delegation of low-risk breast cancer patients' follow-up to non-hospital practitionners (NHP), including gynaecologists and general practitioners, has been assessed prospectively within a care network in the Paris region. Patients with early stage breast cancer were eligible. The follow-up protocol was built according to international guidelines. By 2012, 289 NHPs were following 2266 patients treated in 11 centres. Median follow-up time was 7.4 years. The mean intervals between two consecutive consultations were 9.5 [9.2-9.8] months for women supposed to be monitored every 6 months and 12.5 [12.2-12.8] for those requiring annual monitoring. The relapse rate was 3.2% [2.1-4.3] at 5 years and 7.8% [5.9-9.7] at 10 years. Seventy one percent of relapses were diagnosed on a scheduled assessment. Only 6% were lost-to-follow-up. Delegating follow-up after low risk breast cancer to NHPs in a care network is feasible, well accepted and provides an alternative to follow-up in specialized centres., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Background: A subgroup of T1N0M0 breast cancer (BC) carries a high potential of relapse, and thus may require adjuvant systemic therapy (AST)., Patients and Methods: Retrospective analysis of all patients with T1 BC, who underwent surgery from January 1999 to December 2009 at 13 French sites. AST was not standardized., Results: Among 8100 women operated, 5423 had T1 tumors (708 T1a, 2208 T1b and 2508 T1c 11-15 mm). T1a differed significantly from T1b tumors with respect to several parameters (lower age, more frequent negative hormonal status and positive HER2 status, less frequent lymphovascular invasion), exhibiting a mix of favorable and poor prognosis factors. Overall survival was not different between T1a, b or c tumors but recurrence-free survival was significantly higher in T1b than in T1a tumors (P = 0.001). In multivariate analysis, tumor grade, hormone therapy and lymphovascular invasion were independent prognostic factors., Conclusion: Relatively poor outcome of patients with T1a tumors might be explained by a high frequency of risk factors in this subgroup (frequent negative hormone receptors and HER2 overexpression) and by a less frequent administration of AST (endocrine treatment and chemotherapy). Tumor size might not be the main determinant of prognosis in T1 BC.

Cochlin, an extracellular matrix protein, shares homologies with the Factor C, a serine protease found in horseshoe crabs, which is critical for antibacterial responses. Mutations in the COCH gene are responsible for human DFNA9 syndrome, a disorder characterized by neurodegeneration of the inner ear that leads to hearing loss and vestibular impairments. The physiological function of cochlin, however, is unknown. Here, we report that cochlin is specifically expressed by follicular dendritic cells and selectively localized in the fine extracellular network of conduits in the spleen and lymph nodes. During inflammation, cochlin was cleaved by aggrecanases and secreted into blood circulation. In models of lung infection with Pseudomonas aeruginosa and Staphylococcus aureus, Coch(-/-) mice show reduced survival linked to defects in local cytokine production, recruitment of immune effector cells, and bacterial clearance. By producing cochlin, FDCs thus contribute to the innate immune response in defense against bacteria., (Copyright © 2013 Elsevier Inc. All rights reserved.)

We previously showed that at acid pH, the transcription of norB, encoding the NorB efflux pump, increases due to a reduction in the phosphorylation level of MgrA, which in turn leads to a reduction in bacterial killing by moxifloxacin, a substrate of the NorB efflux pump. In this study, we demonstrated that reduced oxygen levels did not affect the transcript levels of mgrA but modified the dimerization of the MgrA protein, which remained mostly in its monomeric form. Under reduced aeration, we also observed a 21.7-fold increase in the norB transcript levels after 60 min of growth that contributed to a 4-fold increase in the MICs of moxifloxacin and sparfloxacin for Staphylococcus aureus RN6390. The relative proportions of MgrA in monomeric and dimeric forms were altered by treatment with H(2)O(2), but incubation of purified MgrA with extracts of cells grown under reduced but not normal aeration prevented MgrA from being converted to its dimeric DNA-binding form. This modification was associated with cleavage of a fragment of the dimerization domain of MgrA without change in MgrA phosphorylation and an increase in transcript levels of genes encoding serine proteases in cells incubated at reduced aeration. Taken together, these data suggest that modification of MgrA by proteases underlies the reversal of its repression of norB and increased resistance to NorB substrates in response to reduced-aeration conditions, illustrating a third mechanism of posttranslational modification, in addition to oxidation and phosphorylation, that modulates the regulatory activities of MgrA.

Intensive use of antimicrobial agents in health care settings not only leads to the selection of multiresistant nosocomial isolates of Staphylococcus aureus but may also promote endogenous, resistance-conferring mutations in bacterial genes that encode drug targets. We evaluated the spectrum of rifampin resistance-conferring mutations in cultures of methicillin-susceptible S. aureus (MSSA) or methicillin-resistant S. aureus (MRSA) strains exposed in vitro to sub-MICs of ciprofloxacin. Growth of ciprofloxacin-susceptible MRSA strain MRGR3 and ciprofloxacin-resistant MSSA strain RA1 (a NCTC 8325 derivative) in the presence of 1/2× or 1/4× MIC of ciprofloxacin led to higher frequencies of rifampin-resistant mutants on agar supplemented with rifampin (0.25 mg/liter) than under ciprofloxacin-free conditions. While rifampin-resistant mutants from ciprofloxacin-free cultures essentially showed single-amino-acid substitutions, a significant proportion of rifampin-resistant mutants from ciprofloxacin-exposed cultures displayed in-frame deletions or insertions in the rpoB gene at several positions of the rifampin resistance cluster I. In-frame deletions or insertions were also recorded in rpoB cluster I of rifampin-resistant mutants from ciprofloxacin-exposed cultures of mutS and mutL DNA repair mutants of ciprofloxacin-resistant S. aureus strain RA1. Frequencies of rifampin-resistant mutants grown under ciprofloxacin-free medium were higher for mutant strains RA1 mutS2 and RA1 mutL, but not RA1 recA, than for their parent RA1. In conclusion, ciprofloxacin-mediated DNA damage in S. aureus, as exemplified by the wide diversity of deletions or insertions in rpoB, suggests the occurrence of major, quinolone-mediated disturbances in DNA fork progression and replication repair. Besides promoting antibiotic resistance, accumulation of unrepaired DNA replication errors, including insertions and deletions, may also contribute to potentially lethal mutations.