What’s Known

Several studies have examined the anti-bacterial effect of both Satureja khuzestanica Jamzad (SKJ) and Zataria multiflora Boiss (ZM). Previous studies have shown carvacrol and thymol as the active ingredients of SKJ and ZM.

What’s New

We reviewed studies published during 2000-2017. The minimum inhibitory concentration value of essential oils from SKJ and ZM for bacterial strains was in the range of 0.31-450 and 2-8,000 μg/mL, respectively. The carvacrol content of SKJ was reported between 38.33-97.89% and the amount of thymol in ZM ranged between 25.70-64.87%.

Introduction

Pathogenic bacteria are microorganisms that can cause infectious diseases in humans. ¹ Antibiotics were first introduced in the 1940s and led to a major advancement in the pharmaceutical industry to fight against pathogenic microorganisms. ² Nowadays, the use of antibiotics is common, but their excessive or improper use leads to antibiotic resistance. ³ Antibiotic-resistant pathogenic bacteria are a serious threat to humans and have affected many patients worldwide. ^{4 , 5} Misuse of antibiotics reduces the effectiveness of the therapy to the extent that higher dosages might be required. ^{3 , 6}

Pseudomonas aeruginosa (P. aeruginosa) is a common Gram-negative bacteria and a major cause of chronic or acute nosocomial and burn wound infections. ⁷ A study in China reported that the most common strains, in descending order, were Acinetobacter baumannii, Proteus mirabilis, and P. aeruginosa. ⁸ A systematic review and meta-analysis showed that Gram-negative pathogens (P. aeruginosa, Klebsiella pneumoniae, Escherichia coli, Enterobacter spp., and Proteus spp.) were the most common Gram-negative bacteria isolated from clinically infected burn wounds. ⁹ A similar study in Iran reported P. aeruginosa, Acinetobacter, and Klebsiella as the most common Gram-negative and Staphylococcus aureus as the most common Gram-positive organisms isolated from Iranian burn patients. ¹⁰

P. aeruginosa is an opportunist and a Gram-negative bacillus, which has shown resistance to antibiotics. ¹¹ Recently, a high prevalence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) bacterial strains have been reported. ¹² MDR P. aeruginosa strain is defined by the resistance of the bacterium to three common antibiotic classes, whereas XDR refers to organisms resistant to carbapenem, amikacin, and colistin as well as the three common antibiotic classes. ¹³ In recent years, the spread and sudden outbreak of MDR strains have emerged as an important public health concern ¹⁴ to the extent that the World Health Organization(WHO) named 2011 as the year of antibiotic resistance. ¹⁵ Consequently, due to the broad range of antibiotic resistance and subsequent complications, scientists have become interested in exploring traditional medicine to identify a new source of anti-bacterial agents. A review study over a period of 30 years (1981-2010), on natural products as sources of new drugs, reported that about 80% of the world’s population resort to herbal medicine as part of their treatment. ¹⁶ Traditional medicine is also popular in Iran, since the region has eleven different climates and over 7,500 herbaceous species; a suitable platform for the acquisition of rare medicinal plants. Currently, 25% of the existing drugs are derived from such plants. Iran is one of the countries with a variety of medicinal plants with different characteristics, such as Satureja khuzestanica Jamzad (SKJ) and Zataria multiflora Boiss (ZM). ¹⁷

SKJ locally called Marzeh Khuzestani, belongs to the Laminaceae family. It grows in the south and southwest of Iran and is a subshrub with a branched stem of about 30 cm high and dense leaves. ¹¹ In traditional medicine, it is used as an analgesic, anti-inflammatory, anti-thyroid, anti-oxidant, diuretic, appetizer, anti-bacterial, and antiseptic agent. Most of these features are attributed to carvacrol, which is the active ingredient of SKJ essential oil. ^{18 , 19} ZM locally called avishan-e-shirazi (shirazi thyme), is a thyme-like plant from the Lamiaceae family. It is a wild plant that grows in Iran, Pakistan, and Afghanistan. This plant is known to be effective as an antiseptic, carminative, stimulant, analgesic, diuretic, anesthetic, anti-spasmodic, diaphoretic, and anti-bacterial agent. ²⁰

Due to the importance of SKJ and ZM in herbal medicine and the existence of numerous studies regarding their effects against Pseudomonas, there was a need for a review study. Hence, the present study aimed to conduct a systematic review to determine the anti-bacterial activity and the minimum inhibitory concentration (MIC) of SKJ and ZM essential oils against P. aeruginosa in vitro.

Materials and Methods

Search Strategy

To identify all relevant published studies on SKJ and ZM, we searched Google Scholar, Science Direct, Web of Science, MEDLINE, PubMed, Scopus, Cochrane Library, Academic Search, and Journal Storage databases. In addition, four Persian scientific search engines including Magiran, Irandoc, Scientific Information Database (SID), and IranMedex were searched. The keywords used for the search were S. khuzestanica, marzeh-e-khuzestani, Z. multiflora, Z. multiflora Boiss, avishan-e-shirazi, shirazi thyme, Z. bracteatai Boiss, Z. multiflora var. elatior Boiss, thymol, carvacrol, P. aeruginosa, Iran, Anti-bacterial effect, herbal plant, traditional medicine, phytomedicine, herbal medicine, medicinal plants, plant extracts, essential oils, culinary herbs, folk medicine, and herbal essence. We also searched the references cited in these articles to find other relevant studies. The search was conducted in accordance with the MOOSE checklist and covered all original observational, descriptive, and analytical studies during 2000-2017 both in English and Persian.

Inclusion and Exclusion Criteria

Of the obtained articles/abstracts, those with the following features were included in the study: full-text articles published during 2000-2017, studies on P. aeruginosa microorganism, and studies on the effect of SKJ and ZM against P. aeruginosa. The exclusion criteria were studies that did not address microbiology (especially in relation to Pseudomonas), publications prior to 2000, irregular articles (abstract only, case reports, meeting reports, congress articles), articles with unclear results or data analysis, articles reported in languages other than English or Persian, and duplicated publications (articles, review papers, meta-analysis, systematic reviews).

Quality Assessment of Included Articles

The selected articles were assessed based on the quality of the study, design, methods, context, findings, data analysis, and interpretations. All articles not meeting the pre-defined standard in each of the mentioned items were excluded.

Data Extraction

Following a careful and detailed study of the full-text articles, information such as the name of the first author, publication year, location where the plant was collected, plant parts used and drying conditions, essential oil analysis, the source of isolates, abundant compounds, carvacrol and thymol content, and general remarks were extracted. The information was then entered in an abstract format.

Results

The morphology of SKJ and ZM is shown in figure 1. In the isobilateral amphistomatic structure of SJK leaves, there are both glandular, peltate and capitate, and two types of non-glandular trichomes. The peltate glandular trichomes comprise of a five-cell multiseriate stalk and a 12-cell enlarged secretory head. On the other hand, the capitate trichomes show variable morphologies. Dried leaves of SKJ are recognized by their oval-shaped hygromorphic diacytic stomata which have an adaxial stomatal index of 13.54. Other morphological features are collateral vascular packs consisting of xylem, as well as a three-layer sclerenchymatous tissue near phloem. Another feature includes prismatic alongside with raphide calcium oxalate crystals. The oval-shaped leaves with an orbicular thickly gland-dotted structure, along with the dense white, hairy, and round buds on the leaf axils are main features characterizing ZM.

Figure 1. The morphology of S. khuzestanica (A) and Z. multiflora (B)

As shown in figure 2, initially 117 studies were identified through English and Persian database searching. Based on the exclusion criteria, 32 articles were excluded due to duplication, and thus 85 articles remained for eligibility evaluation. A further three articles were excluded due to their format, such as study design, book, congress, thesis, publication prior to the year 2000, or written in other languages. In the next step, the abstracts of 82 articles were screened of which 49 were excluded due to subject irrelevance. Subsequently, 33 full-text articles were evaluated from which 16 were excluded due to the incompleteness of the data. Finally, 17 articles on the studies related to inhibitory effects on P. aeruginosa (SKJ: 7 studies, ZM: 10 studies) were included in the present meta-analysis.

Figure 2. The Moose flowchart for article screening.

As described in table 1, the majority of the Iranian researchers collected the SKJ plants from Khuzestan and Lorestan provinces. Based on gas chromatography-mass spectrometry (GC-MS) analysis, the rate of carvacrol, as the major active component of SKJ, was reported between 38.33-97.89%. ²² The major ingredients of ZM were carvacrol (16.8-82.7%) followed by thymol (27.5-64.87%). The MIC value of SKJ and ZM essential oils for bacterial strains was in the range of 0.31-450 and 2-8000 μg/mL, respectively. Based on the results, SKJ inhibited the growth of P. aeruginosa less than ZM. The ZM plants were collected from the provinces of Fars, Guilan, Lorestan, Hormozgan, Yazd, Khorasan Razavi, Golestan, Sistan-Baluchestan, Kerman, and Isfahan (table 2). The major ingredients of ZM were carvacrol followed by thymol in various concentrations.

Discussion

The review of the articles showed that the level of carvacrol, as the major active component of SKJ, was between 38.33-97.89%. ²² Major ingredients of ZM were carvacrol (16.8-82.7%) ^{31 , 34} followed by thymol (25.7-64.87%). ^{30 , 33} The abundant presence of these ingredients explains their anti-bacterial effect of SKJ and ZM. The MIC values in Satureja khuzestanica essential oil (SKEO) and Zataria multiflora essential oil (ZMEO) for bacterial strains were in the range of 0.31-450 and 2-8,000 μg/mL, respectively. Therefore, SKJ inhibited the growth of P. aeruginosa less than ZM. Variations in the quantitative composition of carvacrol and thymol compounds in the Lamiaceae family were likely due to the geographical area, genetic diversity, climatic conditions, the existence of different chemotypes, and/or ecological differences. ³⁷ Note that essential oil yield is associated with the concentration of essential elements and the amount of organic matter in the environment. ³⁸

P. aeruginosa has a high level of intrinsic resistance to most anti-bacterial agents due to the presence of an outer membrane barrier. The compounds carvacrol, gamma-terpinene, p-cymene, and thymol possess high hydrophobic properties to overcome such outer membrane barrier. The discharge of lipids from the bacterial cell wall is their functional mechanism. However, increased permeability of the membrane might also be the result of an ion ejection and electron imbalance. ³⁹ The anti-microbial activity of phenolic compounds might be due to the location of the hydroxyl group in these compounds, which is vital for better efficacy of these natural ingredients. ⁴⁰ The review of the articles showed that SKJ and ZM have anti-bacterial effects against both susceptible and resistant P. aeruginosa strains. Despite some difference in MIC values, all studies indicated the anti-microbial activity of SKEO and ZMEO in various ranges and degrees. Consistent with studies in Iran, a study in India reported a significant correlation between the anti-microbial activity and carvacrol from SKJ and ZM. ⁴¹ Another study showed that SKJ could lead to a decrease in drug resistance and inhibition of exoA gene expression in P. aeruginosa. ¹¹ SKJ, due to its acceptable anti-bacterial effect, is recommended as an alternative disinfectant to control the nosocomial resistant micro-organisms. However, further comprehensive studies and clinical trials are required to approve the use of such natural disinfectants in health care and pharmacopeia systems. ²²

The use of herbal essences in combination with currently available anti-microbial agents is a promising option. Their synergistic and additive effects could be potentially effective in the fight against pathogens. Consequently, lower doses of toxic agents would have to be used to control micro-organisms. ⁴¹ In line with the reviewed articles, another study showed that the combination of essential oils with a standard dose of antibiotics, due to their synergistic interaction, may have a potential benefit in controlling pathogens or inhibiting their growth. In other words, the efficacy of the combined anti-microbial agents leads to the use of lower doses of toxic antibiotics, and consequently a significant reduction in the inhibitory concentrations of anti-microbial agents in vitro.^{42 , 43} In fact, the use of natural herbs is beneficial in eliminating the side effects of anti-oxidant and anti-bacterial agents. ²⁵ Based on the reviewed articles, it can be concluded that the anti-bacterial effect of essential oil is higher than extracts, which is attributed to their phenolic components (e.g., carvacrol and thymol).

Overall, in spite of some differences in MIC, all articles acknowledged the anti-bacterial/anti-Pseudomonal characteristics of both plants; attributed to their phenolic components (carvacrol, thymol). In those studies, antibiotic susceptibility testing (disk diffusion method) and MIC were used in vitro. The anti-microbial effect of carvacrol and thymol is due to the permeability of the cell membrane. They can disrupt the cations of the mucous membrane and consequently its vital activities. ⁴⁴ Thymol inhibits the activity of ATPase and increases the non-specific permeability of the bacterial cell membrane. It not only prevents the formation of a microbial population, but also increases the permeability of the bacterial membrane, which makes the bacteria more susceptible and vulnerable. Carvacrol inhibits the neutrophilic elastase enzyme and the production of Prostaglandin E2 (PGE2), F1, and F2. ⁴⁵ However, further studies are required to better understand the mechanisms of their anti-microbial activity against pathogenic micro-organisms as well as their safety, effectiveness, and toxicity.

The main limitation of the present study was the lack of access to all articles, including unpublished research. Additionally, we did not contact the authors of the included studies to obtain further data, nor approached experts in this field to obtain clarifications. Furthermore, the review did not include articles in other languages than Persian and English.

Conclusion

Overall, this review study confirmed the anti-bacterial activity of SKJ and ZM, particularly against Pseudomonas in vitro. Further studies are required to evaluate the use of plant extracts as natural anti-bacterial agents in packaged food, effects of herbal essential oils as complementary medicine, or as a replacement for synthetic antibiotics. Proper interaction between the essential oils and standard drug dosage could be a challenge in vivo.

References

1. McFall-Ngai M. Adaptive immunity: care for the community. Nature. 2007; 445:153. DOI | PubMed
2. Alanis AJ. Resistance to antibiotics: are we in the post-antibiotic era?. Arch Med Res. 2005; 36:697-705. DOI | PubMed
3. Hosseini SM, Naeini NS, Khaledi A, Daymad SF, Esmaeili D. Evaluate the Relationship Between Class 1 Integrons and Drug Resistance Genes in Clinical Isolates of Pseudomonas aeruginosa. Open Microbiol J. 2016; 10:188-96. Publisher Full Text | DOI | PubMed
4. Green VL, Verma A, Owens RJ, Phillips SE, Carr SB. Structure of New Delhi metallo-beta-lactamase 1 (NDM-1). Acta Crystallogr Sect F Struct Biol Cryst Commun. 2011; 67:1160-4. Publisher Full Text | DOI | PubMed
5. Fernandez A, Pereira MJ, Suarez JM, Poza M, Trevino M, Villalon P. Emergence in Spain of a multidrug-resistant Enterobacter cloacae clinical isolate producing SFO-1 extended-spectrum beta-lactamase. J Clin Microbiol. 2011; 49:822-8. Publisher Full Text | DOI | PubMed
6. Reyes LF, Babu BL, Aliberti S, Sibila O, Anzueto A, Restrepo MI. Global Burden And Risk Factors Of Drug-Resistant Pseudomonas Aeruginosa In Patients With Community-Acquired Pneumonia: An Multinational Point Prevalence Study. Am J Respir Crit Care Med. 2017; 195:A6858.
7. Einabadi M, Abdolerahmani F, Yousefi Mashoof R, Vazini H, Khaledi A, Piroozmand A. Study of drug resistance of Staphylococcus aurous and Pseudomonas aeruginosa strains isolated from environmental samples of Hamadan educational hospitals in 2017 using disk diffusion and minimum inhibitory concentration. Feyz. 2018; 22:206-13.
8. Wang Z, Rong XZ, Zhang T, Liu LZ. Distribution and drug resistance analysis of bacteria in different wound infections. Nan Fang Yi Ke Da Xue Xue Bao. 2009; 29:82-3. PubMed
9. Azzopardi EA, Azzopardi E, Camilleri L, Villapalos J, Boyce DE, Dziewulski P. Gram negative wound infection in hospitalised adult burn patients-systematic review and metanalysis. PloS one. 2014; 9:e95042. DOI
10. Rezaei E, Safari H, Naderinasab M, Aliakbarian H. Common pathogens in burn wound and changes in their drug sensitivity. Burns. 2011; 37:805-7. DOI | PubMed
11. Abbasi A, Maddah SM, Mahboubi A, Khaledi A, Vazini H, Esmaeili D. Investigate the Inhibitory Effects of Satureja khuzestanica Essential Oil against Housekeeping fabD and exoA Genes of Pseudomonas aeruginosa from Hospital Isolates using RT-PCR Technique. Ann Med Health Sci Res. 2017.
12. Denyer SP, Hodges NA, Gorman SP. Hugo and Russell’s pharmaceutical microbiology. John Wiley & Sons: New Jersey; 2008.
13. Magiorakos AP, Srinivasan A, Carey RB, Carmeli Y, Falagas ME, Giske CG. Multidrug-resistant, extensively drug-resistant and pandrug-resistant bacteria: an international expert proposal for interim standard definitions for acquired resistance. Clin Microbiol Infect. 2012; 18:268-81. DOI | PubMed
14. Ventola CL. The antibiotic resistance crisis: part 1: causes and threats. P T. 2015; 40:277-83. Publisher Full Text | PubMed
15. Leung E, Weil DE, Raviglione M, Nakatani H, World Health Organization World Health Day Antimicrobial Resistance Technical Working G. The WHO policy package to combat antimicrobial resistance. Bull World Health Organ. 2011; 89:390-2. Publisher Full Text | DOI | PubMed
16. Newman DJ, Cragg GM. Natural products as sources of new drugs over the 30 years from 1981 to 2010. J Nat Prod. 2012; 75:311-35. Publisher Full Text | DOI | PubMed
17. Khanahmadi M, Rezazadeh S. Review on Iranian medicinal plants with antioxidant properties. Journal of Medicinal Plants. 2010; 3:19-32.
18. Assaei R, Mostafavi-Pour Z, Pajouhi N, Ranjbar Omrani GH, Sepehrimanesh M, Zal F. Effects of essential oil of Satureja khuzestanica on the oxidative stress in experimental hyperthyroid male rat. Vet Res Forum. 2015; 6:233-8. Publisher Full Text | PubMed
19. Hadian J, Akramian M, Heydari H, Mumivand H, Asghari B. Composition and in vitro antibacterial activity of essential oils from four Satureja species growing in Iran. Nat Prod Res. 2012; 26:98-108. DOI | PubMed
20. Sharififar F, Moshafi M, Mansouri S, Khodashenas M, Khoshnoodi M. In vitro evaluation of antibacterial and antioxidant activities of the essential oil and methanol extract of endemic Zataria multiflora Boiss. Food Control. 2007; 18:800-5. DOI
21. Moghaddam M, Miran SNK, Pirbalouti AG, Mehdizadeh L, Ghaderi Y. Variation in essential oil composition and antioxidant activity of cumin (Cuminum cyminum L.) fruits during stages of maturity. Ind Crops Prod. 2015; 70:163-9. DOI
22. Amiri M, Esmaeili D, Sahlehnia A, Ariana M, Alam F, Beiranvand H. Study of antibacterial effects of Satureja essence against some common nosocomial pathogenic bacteria. Int J Curr Microbiol App Sci. 2013; 2:249-54.
23. Siavash Saei-Dehkordi S, Fallah AA, Heidari-Nasirabadi M, Moradi M. Chemical composition, antioxidative capacity and interactive antimicrobial potency of Satureja khuzestanica Jamzad essential oil and antimicrobial agents against selected food-related microorganisms. Int J Food Sci Technol. 2012; 47:1579-85. DOI
24. Yousefzadi M, Riahi-Madvar A, Hadian J, Rezaee F, Rafiee R, Biniaz M. Toxicity of essential oil of Satureja khuzistanica: in vitro cytotoxicity and anti-microbial activity. J Immunotoxicol. 2014; 11:50-5. DOI | PubMed
25. Bahrami B, Mahboubi M, Yari R, Mehran M. The antimicrobial and antioxidant potencies of Satureja Khuzistanica essential oil for preserving of vegetable oils. J Microbiol Biotechnol Food Sci. 2016; 6:979-82. DOI
26. Abbasi A, Bahador A, Esmaeili D, Mahbubi A, Amiri M, Amiri M. The study of inhibitory effects of satureja khuzestanica against MDR isolates of pseudomonas aeruginosa. Int J Curr Microbiol App Sci. 2014; 3:614-8.
27. Faezeh F, Salome D, Abolfazl D, Reza ZM. Considering the antibacterial activity of Zataria multiflora Boiss essential oil treated with gamma-irradiation in vitro and in vivo systems. Radiat Phys Chem. 2015; 106:145-50. DOI
28. Heidary M, Hashemi A, Goudarzi H, Khoshnood S, Roshani M, Azimi H. The antibacterial activity of Iranian plants extracts against metallo beta-lactamase producing Pseudomonas aeruginosa strains. J Paramed Sci. 2016; 7:13-9.
29. Fallah F, Taherpour A, Borhan RS, Hashemi A, Habibi M, Sajadi Nia R. Evaluation of Zataria MultiFlora Boiss and Carum copticum antibacterial activity on IMP-type metallo-beta-lactamase-producing Pseudomonas aeruginosa. Ann Burns Fire Disasters. 2013; 26:193-8. Publisher Full Text | PubMed
30. Saei-Dehkordi SS, Tajik H, Moradi M, Khalighi-Sigaroodi F. Chemical composition of essential oils in Zataria multiflora Boiss. from different parts of Iran and their radical scavenging and antimicrobial activity. Food Chem Toxicol. 2010; 48:1562-7. DOI | PubMed
31. Zomorodian K, Saharkhiz MJ, Rahimi MJ, Bandegi A, Shekarkhar G, Bandegani A. Chemical composition and antimicrobial activities of the essential oils from three ecotypes of Zataria multiflora. Pharmacogn Mag. 2011; 7:53-9. Publisher Full Text | DOI | PubMed
32. Owlia P, Saderi H, Rasooli I, Sefidkon F. Antimicrobial characteristics of some herbal Oils on Pseudomonas aeruginosa with special reference to their chemical compositions. Iranian Journal of Pharmaceutical Research. 2010;107-14.
33. Mahammadi Purfard A, Kavoosi G. Chemical composition, radical scavenging, antibacterial and antifungal activities of Zataria multiflora bioss essential oil and aqueous extract. J Food Saf. 2012; 32:326-32. DOI
34. Avaei A, Mohamadi SA, Mahmoodzadeh VB. Chemical composition and antimicrobial effect of the essential oil of Zataria multiflora Boiss endemic in Khorasan-Iran. Asian Pac J Trop Dis. 2015; 5:181-5. DOI
35. Saeidi S, Hassanpour K, Ghamgosha M, Heiat M, Taheri RA, Mirhosseini A. Antibacterial activity of ethyl acetate and aqueous extracts of Mentha longifolia L. and hydroalcoholic extract of Zataria multiflora Boiss. plants against important human pathogens. Asian Pac J Trop Med. 2014; 7:S186-9. DOI | PubMed
36. Varposhti M, Abdi Ali A, Mohammadi P, Saboora A. Effects of extracts and an essential oil from some medicinal plants against biofilm formation of Pseudomonas aeruginosa. Journal of Medical Microbiology and Infectious Diseases. 2013; 1:36-40.
37. Runyoro D, Ngassapa O, Vagionas K, Aligiannis N, Graikou K, Chinou I. Chemical composition and antimicrobial activity of the essential oils of four Ocimum species growing in Tanzania. Food Chemistry. 2010; 119:311-6. DOI
38. Yavari A, Nazeri V, Sefidkon F, Hassani ME. Influence of some environmental factors on the essential oil variability of Thymus migricus. Nat Prod Commun. 2010; 5:943-8. PubMed
39. Bakkali F, Averbeck S, Averbeck D, Idaomar M. Biological effects of essential oils--a review. Food Chem Toxicol. 2008; 46:446-75. DOI | PubMed
40. Bahmani M, Rafieian-Kopaei M, Hassanzadazar H, Taherikalani M. Pseudomoniasis phytotherapy: a review on most important Iranian medicinal plants effective on Pseudomonas aeruginosa. Iran J Microbiol. 2016; 8:347-50. Publisher Full Text | PubMed
41. Khan MS, Ahmad I. Antifungal activity of essential oils and their synergy with fluconazole against drug-resistant strains of Aspergillus fumigatus and Trichophyton rubrum. Appl Microbiol Biotechnol. 2011; 90:1083-94. DOI | PubMed
42. Mahboubi M, Ghazian Bidgoli F. In vitro synergistic efficacy of combination of amphotericin B with Myrtus communis essential oil against clinical isolates of Candida albicans. Phytomedicine. 2010; 17:771-4. DOI | PubMed
43. Silva F, Ferreira S, Duarte A, Mendonca DI, Domingues FC. Antifungal activity of Coriandrum sativum essential oil, its mode of action against Candida species and potential synergism with amphotericin B. Phytomedicine. 2011; 19:42-7. DOI | PubMed
44. Sharifian M, Bolhari B, Nosrat A, Aligholi M. The effect of carvacerol on Enterococcus faecalis as an intracanal medicament-Invitro study. J Dent Med. 2009; 1:35-40.
45. Laarman AJ, Bardoel BW, Ruyken M, Fernie J, Milder FJ, van Strijp JA. Pseudomonas aeruginosa alkaline protease blocks complement activation via the classical and lectin pathways. J Immunol. 2012; 188:386-93. DOI | PubMed