Irfan Ahmad Lab

Bacteria are equipped with sophisticated tools to ensure a timely response to adverse conditions imposed by chemically or physically. For that, cell signaling from second messengers plays an important role. We are aiming to complete molecular circuit of events taking place in bacterial cells to mediate adaptive response to antibiotics.

When multi drug resistant microbes become tolerant to commonly used antibiotics, the infections become difficult to treat. Our aim is to illustrate molecular mechanisms by which bacteria acquire tolerance to commonly used antibiotics using Acinetobacter baumannii as a model organism. 

Using a combination of genetic engineering tools, immunofluorescence microscopic visualization of bacterial surface components and molecular epidemiology of drug tolerant microbes, we investigate molecular signaling pathways required to mediate bacterial adaptation upon antibiotic exposure and other environmental related stress. 

Financing

The research is financed by the Swedish Research Council, Kempestiftelserna and the Swedish Foundation for International Cooperation in Research and Higher Education, STINT.

Publications

Selected publications

1. Emergence of high colistin resistance in carbapenem resistant Acinetobacter baumannii in Pakistan and its potential management through immunomodulatory effect of an extract from Saussurea lappa” Ahsan U, Mushtaq F, Saleem S, Malik A,Sarfaraz, Shahzad M, Uhlin BE and Ahmad I*. Front. Pharmacol. (2022) 13:986802. doi: 10.3389/fphar.2022.986802         

2. A c-di-GMP signalling network regulates biofilm formation and surface associated motility in Acinetobacter baumannii. Ahmad I*, Nygren E, Khalid F, Myint SL and Uhlin BE. Scientific Reports (2020) 10(1):1991. doi: 10.1038/s41598-020-58522-5.

3. Molecular epidemiology and antimicrobial resistance features of Acinetobacter baumannii clinical isolates from Pakistan. Karah N, Khalid F, Wai SN, Uhlin BE and Ahmad I*.  Annals of Clinical Microbiology and Antimicrobials. (2020), doi: 10.1186/s12941-019-0344-7

4. Type 1 fimbriae and motility play a pivotal role during interactions of Salmonella typhimurium with Acanthamoeba castellanii (T4 genotype). Mannan T, Rafique MW, Bhatti MH, Matin A and Ahmad I*. Current Microbiology (2020). doi: 10.1007/s00284-019-01868-5

5. Analysis of colony phase variation switch in Acinetobacter baumannii clinical isolates. Ahmad I, Karah N, Nadeem A, Wai SN, Uhlin BE. PLoS One. 2019 Jan 4;14(1):e0210082 doi: 10.1371/journal.pone.0210082. 

6. The cellulose synthase BcsA plays a role in interactions of Salmonella typhimurium with Acanthamoeba castellanii genotype T4. Gill MA, Rafique MW, Manan T, Slaeem S, Römling U, Matin A, Ahmad I*. Parasitology Research. 2018 Jul;117(7):2283-2289. doi: 10.1007/s00436-018-5917-4. 

7. Stand-Alone EAL Domain Proteins Form a Distinct Subclass of EAL Proteins Involved in Regulation of Cell Motility and Biofilm Formation in Enterobacteria. El Mouali Y, Kim H, Ahmad I, Brauner A, Liu Y, Skurnik M, Galperin MY, Römling U. Journal of Bacteriology. 2017 Aug 22;199(18). doi: 10.1128/JB.00179-17.

8. Detailed analysis of c-di-GMP mediated regulation of csgD expression in Salmonella typhimurium. Ahmad I, Cimdins A, Beske T, Römling U. BMC Microbiology. 2017 Feb 2;17(1):27. doi: 10.1186/s12866-017-0934-5

9. Draft Genome Sequences of Semi constitutive Red, Dry, and Rough Biofilm-Forming Commensal and Uropathogenic Escherichia coli Isolates. Cimdins A, Lüthje P, Li F, Ahmad I, Brauner A, Römling U. Genome Announc. 2017 Jan 26;5(4). doi: 10.1128/genomeA.01249-16

10.  BcsZ inhibits biofilm phenotypes and promotes virulence by blocking cellulose production in Salmonella entericaserovar Typhimurium. Ahmad I, Rouf SF, Sun L, Cimdins A, Shafeeq S, Le Guyon S, Schottkowski M, Rhen M, Römling U. Microbial Cell Factories 2016, 15(1):177.  doi: 10.1186/s12934-016-0576-6

11.  Regulation of biofilm formation in Salmonella entericaserovar Typhimurium. Simm R, Ahmad I, Rhen M, Le Guyon S, Römling U. Future Microbiology. 2014;9(11):1261-82. doi: 10.2217/fmb.14.88.

12.  GIL, a new c-di-GMP-binding protein domain involved in regulation of cellulose synthesis in Enterobacteria.Fang X, Ahmad I, Blanka A, Schottkowski M, Cimdins A, Galperin MY, Römling U, Gomelsky M. Mol Microbiol. 2014 Aug;93(3):439-52. doi: 10.1111/mmi.12672.

13.  The EAL-like protein STM1697 regulates virulence phenotypes, motility and biofilm formation in Salmonella typhimurium. Ahmad I, Wigren E, Le Guyon S, Vekkeli S, Blanka A, El Mouali Y, Anwar N, Chuah ML, Lünsdorf H, Frank R, Rhen M, Liang ZX, Lindqvist Y, Römling U. Mol Microbiol. 2013 Dec;90(6):1216-32. doi: 10.1111/mmi.12428. 

14.  Hfq and Hfq-dependent small RNAs are major contributors to multicellular development in Salmonella enterica serovar Typhimurium.  Monteiro C, Papenfort K, Hentrich K, Ahmad I, Le Guyon S, Reimann R, Grantcharova N, Römling U.RNA Biol. 2012 Apr;9(4):489-502. doi: 10.4161/rna.19682.

15.  Complex c-di-GMP signaling networks mediate transition between virulence properties and biofilm formation in Salmonella enterica serovar Typhimurium. Ahmad I, Lamprokostopoulou A, Le Guyon S, Streck E, Barthel M, Peters V, Hardt WD, Römling U. PLoS One 2011;6(12):e28351. doi: 10.1371/journal.pone.0028351.    

16.  Regulation of biofilm components in Salmonella enterica serovar Typhimurium by lytic transglycosylases involved in cell wall turnover. Monteiro C, Fang X, Ahmad I, Gomelsky M, Römling U. J Bacteriol.  2011 Dec;193(23):6443-51. doi: 10.1128/JB.00425-11.

17.  Opposing contributions of polynucleotide phosphorylase and the membrane protein NlpI to biofilm formation by Salmonella enterica serovar Typhimurium. Rouf SF, Ahmad I, Anwar N, Vodnala SK, Kader A, Römling U, Rhen M. J Bacteriol.  2011 Jan;193(2):580-2. doi: 10.1128/JB.00905-10.

18.  Complex regulatory network encompassing the Csr, c-di-GMP and motility systems of Salmonella typhimurium. Jonas K, Edwards AN, Ahmad I, Romeo T, Römling U, Melefors O. Environ Microbiol.  2010 Feb;12(2):524-40. doi: 10.1111/j.1462-2920.2009.02097.x.

19.  A role for the EAL-like protein STM1344 in regulation of CsgD expression and motility in Salmonella enterica serovar Typhimurium. Simm R, Remminghorst U, Ahmad I, Zakikhany K, Römling U. J Bacteriol. 2009 Jun;191(12):3928-37. doi: 10.1128/JB.00290-09.