Michael M. Petrov

Prof. Dr. Michael M. Petrov

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Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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28 April 2023 in Infection Control & Hospital Epidemiology
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VRVictor Daniel Rosenthal
Victor Daniel Rosenthal
RYRuijie Yin
Ruijie Yin
SMSheila Nainan Myatra
Sheila Nainan Myatra
ZMZiad Memish
Ziad Memish
CRCamilla Rodrigues
Camilla Rodrigues
ZJZhilin Jin
Zhilin Jin
Objective: To identify central-line (CL)–associated bloodstream infection (CLABSI) incidence and risk factors in low- and middle-income countries (LMICs).Design: From July 1, 1998, to February 12, 2022, we conducted a multinational multicenter prospective cohort study using online standardized surveillance system and unified forms.Setting: The study included 728 ICUs of 286 hospitals in 147 cities in 41 African, Asian, Eastern European, Latin American, and Middle Eastern countries.Patients: In total, 278,241 patients followed during 1,815,043 patient days acquired 3,537 CLABSIs.Methods: For the CLABSI rate, we used CL days as the denominator and the number of CLABSIs as the numerator. Using multiple logistic regression, outcomes are shown as adjusted odds ratios (aORs).Results: The pooled CLABSI rate was 4.82 CLABSIs per 1,000 CL days, which is significantly higher than that reported by the Centers for Disease Control and Prevention National Healthcare Safety Network (CDC NHSN). We analyzed 11 variables, and the following variables were independently and significantly associated with CLABSI: length of stay (LOS), risk increasing 3% daily (aOR, 1.03; 95% CI, 1.03–1.04; P < .0001), number of CL days, risk increasing 4% per CL day (aOR, 1.04; 95% CI, 1.03–1.04; P < .0001), surgical hospitalization (aOR, 1.12; 95% CI, 1.03–1.21; P < .0001), tracheostomy use (aOR, 1.52; 95% CI, 1.23–1.88; P < .0001), hospitalization at a publicly owned facility (aOR, 3.04; 95% CI, 2.31–4.01; P <.0001) or at a teaching hospital (aOR, 2.91; 95% CI, 2.22–3.83; P < .0001), hospitalization in a middle-income country (aOR, 2.41; 95% CI, 2.09–2.77; P < .0001). The ICU type with highest risk was adult oncology (aOR, 4.35; 95% CI, 3.11–6.09; P < .0001), followed by pediatric oncology (aOR, 2.51;95% CI, 1.57–3.99; P < .0001), and pediatric (aOR, 2.34; 95% CI, 1.81–3.01; P < .0001). The CL type with the highest risk was internal-jugular (aOR, 3.01; 95% CI, 2.71–3.33; P < .0001), followed by femoral (aOR, 2.29; 95% CI, 1.96–2.68; P < .0001). Peripherally inserted central catheter (PICC) was the CL with the lowest CLABSI risk (aOR, 1.48; 95% CI, 1.02–2.18; P = .04).Conclusions: The following CLABSI risk factors are unlikely to change: country income level, facility ownership, hospitalization type, and ICU type. These findings suggest a focus on reducing LOS, CL days, and tracheostomy; using PICC instead of internal-jugular or femoral CL; and implementing evidence-based CLABSI prevention recommendations.

4 January 2024 in Infection Control & Hospital Epidemiology
Verified
Journal Article
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VRVictor Daniel Rosenthal
Victor Daniel Rosenthal
RYRuijie Yin
Ruijie Yin
EBEric Christopher Brown
Eric Christopher Brown
BLBrandon Hochahn Lee
Brandon Hochahn Lee
CRCamilla Rodrigues
Camilla Rodrigues
ZJZhilin Jin
Zhilin Jin
Objective: To identify urinary catheter (UC)–associated urinary tract infection (CAUTI) incidence and risk factors.Design: A prospective cohort study.Setting: The study was conducted across 623 ICUs of 224 hospitals in 114 cities in 37 African, Asian, Eastern European, Latin American, and Middle Eastern countries.Participants: The study included 169,036 patients, hospitalized for 1,166,593 patient days.Methods: Data collection took place from January 1, 2014, to February 12, 2022. We identified CAUTI rates per 1,000 UC days and UC device utilization (DU) ratios stratified by country, by ICU type, by facility ownership type, by World Bank country classification by income level, and by UC type. To estimate CAUTI risk factors, we analyzed 11 variables using multiple logistic regression.Results: Participant patients acquired 2,010 CAUTIs. The pooled CAUTI rate was 2.83 per 1,000 UC days. The highest CAUTI rate was associated with the use of suprapubic catheters (3.93 CAUTIs per 1,000 UC days); with patients hospitalized in Eastern Europe (14.03) and in Asia (6.28); with patients hospitalized in trauma (7.97), neurologic (6.28), and neurosurgical ICUs (4.95); with patients hospitalized in lower–middle-income countries (3.05); and with patients in public hospitals (5.89).The following variables were independently associated with CAUTI: Age (adjusted odds ratio [aOR], 1.01; P < .0001), female sex (aOR, 1.39; P < .0001), length of stay (LOS) before CAUTI-acquisition (aOR, 1.05; P < .0001), UC DU ratio (aOR, 1.09; P < .0001), public facilities (aOR, 2.24; P < .0001), and neurologic ICUs (aOR, 11.49; P < .0001).Conclusions: CAUTI rates are higher in patients with suprapubic catheters, in middle-income countries, in public hospitals, in trauma and neurologic ICUs, and in Eastern European and Asian facilities.Based on findings regarding risk factors for CAUTI, focus on reducing LOS and UC utilization is warranted, as well as implementing evidence-based CAUTI-prevention recommendations.

1 December 2019 in Journal of Medical Microbiology
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Journal Article
Open access
APAtanaska Petrova
Atanaska Petrova
YFYana Feodorova
Yana Feodorova
TMTsonka Miteva-Katrandzhieva
Tsonka Miteva-Katrandzhieva
MPMichael M. Petrov
Michael M. Petrov
.M.Marianna Atanassova Murdjeva
.Marianna Atanassova Murdjeva
Introduction. Carbapenems are often described as the most effective weapon against infections caused by multidrug-resistant bacteria especially those belonging to the group of non-fermenting bacteria such as Pseudomonas . The main mechanisms leading to resistance are the hyperexpression of certain efflux pumps belonging to the resisto-nodular division and the lower expression of the transmembrane porin OprD, sometimes in combination with excessive production of the intrinsic AmpC. Carbapenemases are assumed to play a secondary role. Aim. The aim of this study was to determine the exact mechanisms of carbapenem resistance in Pseudomonas aeruginosa isolates from the largest Bulgarian University hospital ‘St. George’- Plovdiv. Methodology. A total of 32 clinical isolates collected from different patients’ samples resistant to imipenem and/or meropenem were examined via phenotypic and molecular-genetic tests. Results. No metallo-enzyme production was detected. Three isolates were positive for OXA-50-encoding genes in two of them in combination with other oxacillinases or the bla VEB-1 gene. For the first time, OXA-50-producing P. aeruginosa have been reported in Bulgaria. The increased expression or hyperexpression of MexXY-OprM efflux pump was observed as the main mechanism of resistance. In most cases, it was combined with lower expression or lack of OprD with or without MexAB-OprM hyperexpression. No excessive production of AmpC was detected in comparison to the reference ATCC 27853 P . aeruginosa strain. Conclusion. The increased expression or overexpression of MexXY-OprM efflux pumps is the leading cause of carbapenem resistance in our isolates Pseudomonas , detected in 94 % of the bacteria investigated.

30 September 2025 in Antibiotics
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MRMilena Yancheva Rupcheva
Milena Yancheva Rupcheva
Kostadin Rangelov KostadinovKostadin Rangelov Kostadinov
Kostadin Rangelov Kostadinov
YKYordan Kalchev
Yordan Kalchev
PGPetya Gardzheva
Petya Gardzheva
EHEli Hristozova
Eli Hristozova
MPMichael M. Petrov
Michael M. Petrov
Background: Urinary tract infections (UTIs) are among the most common hospital- and community-acquired infections, creating a substantial healthcare burden due to recurrence, complications, and rising antimicrobial resistance. Accurate diagnosis and timely antimicrobial therapy are essential. This study aimed to identify trends in the etiology, treatment, and resistance patterns of UTIs through a retrospective analysis of urine isolates processed at the Laboratory of Microbiology at University Hospital St. George in Plovdiv, the largest tertiary care and reference microbiology center in Bulgaria, between 2017 and 2022. Materials and Methods: A retrospective single-center study was performed at the hospital’s Microbiology Laboratory. During the study period, 74,417 urine samples from 25,087 hospitalized patients were screened with the HB&L UROQUATTRO system. Positive specimens were cultured on blood agar, Eosin-Methylene Blue, and chromogenic media. Identification was performed using biochemical assays, MALDI-TOF MS, and the Vitek 2 Compact system. Antimicrobial susceptibility testing included disk diffusion, MIC determination, broth microdilution (for colistin), and Vitek 2 Compact, interpreted according to EUCAST standards. Descriptive analysis and temporal resistance trends were evaluated with regression models, and interrupted time-series analysis was applied to assess COVID-19-related effects. Results: Out of 10,177 isolates, Gram-negative bacteria predominated (73%), with Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis as the leading pathogens. Among Gram-positives, Enterococcus faecalis was the most frequent. In the post-COVID-19 period, ESBL production increased in E. coli (34–38%), K. pneumoniae (66–77%), and P. mirabilis (13.5–24%). Carbapenem resistance rose in K. pneumoniae (to 40.6%) and P. aeruginosa (to 24%), while none was detected in E. coli. Colistin resistance increased in K. pneumoniae but remained absent in E. coli and P. aeruginosa. High-level aminoglycoside resistance in E. faecalis was stable (~70%), and vancomycin resistance in E. faecium rose from 4.6% to 8.9%. Conclusions: Both community- and hospital-acquired UTIs in Southeastern Bulgaria are increasingly linked to multidrug-resistant pathogens, particularly ESBL-producing and carbapenem-resistant Enterobacterales. Findings from the region’s largest referral center highlight the urgent need for continuous surveillance, rational antibiotic use, and novel therapeutic approaches.

28 April 2026 in Microorganisms
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Ralitsa RaychevaRalitsa Raycheva
Ralitsa Raycheva
GLGergana Lengerova
Gergana Lengerova
MPMichael M. Petrov
Michael M. Petrov
TKTodor Vesselov Kantardjiev
Todor Vesselov Kantardjiev
Bloodstream infections (BSIs) are associated with substantial morbidity, mortality, and healthcare costs. Conventional diagnostics are limited by delayed results, often postponing appropriate antimicrobial therapy. This review aimed to evaluate the clinical and economic value of rapid microbiological diagnostics in BSI management. A state-of-the-art evidence synthesis was conducted using structured searches of PubMed/MEDLINE, Scopus, Web of Science, EconLit, and Google Scholar (2013–2025). Eligible studies included economic evaluations and clinical studies reporting downstream economic or resource-use outcomes. Screening and data extraction were performed by two reviewers, and findings were narratively synthesized. Fifty-nine studies were included. Rapid diagnostics consistently reduced time to pathogen identification and targeted therapy compared to conventional methods. Molecular platforms provided results within hours, while MALDI-TOF enabled identification within 30–60 min after culture positivity. Clinical benefits included earlier therapy optimization, reduced mortality, and shorter hospital stays, particularly when combined with antimicrobial stewardship programs (ASPs). Economic evaluations demonstrated improved cost-effectiveness, including reduced hospitalization, ICU utilization, and antimicrobial costs. MALDI-TOF with stewardship showed notable cost savings and improved outcomes. However, results varied depending on implementation context, infrastructure, and workflow integration. Rapid microbiological diagnostics offer significant clinical and economic benefits in BSI management, particularly when integrated with stewardship programs. Context-specific implementation is essential to maximize their value across healthcare systems.

20 March 2026 in Antibiotics
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GLGergana Lengerova
Gergana Lengerova
Ralitsa RaychevaRalitsa Raycheva
Ralitsa Raycheva
MPMichael M. Petrov
Michael M. Petrov
TKTodor Vesselov Kantardjiev
Todor Vesselov Kantardjiev
Background: Rapid diagnostic tests (RDTs) for bloodstream infections (BSIs) reduce time to pathogen identification, yet evidence on their real-world economic and clinical value remains inconsistent. This study aimed to compare clinical outcomes, antibiotic utilization, and hospital costs associated with different rapid microbiological identification methods versus standard culture. Methods: A retrospective observational study was conducted in a tertiary university hospital including 115 hospitalized patients with suspected or confirmed BSIs. Multiplex PCR (mPCR), fluorescence in situ hybridization (FISH), and MALDI-TOF MS were compared with conventional culture. Outcomes included mortality, length of stay, antibiotic-days, and direct and indirect hospital costs. Nonparametric and exploratory adjusted analyses were performed. Results: No significant differences were observed across diagnostic groups for age, sex, mortality, or length of stay. Patients tested with mPCR showed higher empirical and total antibiotic-days and increased antibiotic-related costs (p < 0.05). Median direct and indirect hospital costs were numerically lower with FISH and mPCR but did not reach statistical significance. Adjusted analyses confirmed that diagnostic modality was not independently associated with mortality or costs. Conclusions: Rapid diagnostics accelerate identification but demonstrate heterogeneous downstream clinical and economic effects. Their value appears to depend more on local implementation and antimicrobial stewardship integration than on diagnostic speed alone.