ACTA Microbiologica Hellenica (Volume 68, Issue 4)

Applications of MALDI-TOF mass spectrometry in the diagnosis of mycobacterial infections

Αmalia Tzanatou1, Dimitrios Papaventsis2, Georgia Vrioni1, Joseph Papaparaskevas1
1 Department of Microbiology, Medical School, National and Kapodistrian University of Athens
2 National Reference Center for Mycobacteria, Microbiology Laboratory, “Sotiria” Chest Hospital
The genus Mycobacterium includes species like the members of the pathogenic Mycobacterium tuberculosis complex, a major global public health burden, and an ever-increasing number of nontuberculous mycobacterial species, of which approximately 1/3 have been associated with infections linked to substantial morbidity and mortality. Therefore, the rapid and accurate identification of mycobacteria is crucial for disease management.
MALDI-TOF MS technique was introduced for the identification of microorganisms as a common laboratory practice during the last decade. It utilizes the unique for each species, fingerprint-like, protein mass spectra and achieves rapid, easy, reliable and cost-effective identification of bacteria, yeasts, moulds and mycobacteria. As conventional methods for the identification of mycobacteria are time-consuming, MALDI-TOF MS offers a new alternative approach that reduces the turnaround time.
Protocols for inactivation and sample preparation of mycobacteria for MALDI-TOF MS proteins’ analysis have been described in detail and are used in clinical microbiology laboratories. The continuous upgrading of databases through incorporation of an increasing number of mass spectral profiles of mycobacterial species, as well as the development of more powerful software for the analysis with MALDI-TOF MS, are future key goals. Through them, it is believed that a reliable identification of a greater number of mycobacterial species will be achieved and an improved distinction between phylogenetically closely related species could be accomplished, as the latter remains the main limitation of the method. Finally, MALDI-TOF MS analysis of surface lipids, specific to each mycobacterial species, is a field of research which developments are expected and promises to further shorten the identification time of mycobacteria, and perhaps even achieving their typing.
The prospects launched by the introduction of MALDI-TOF MS technology in the diagnosis of mycobacteria have had a spectacular impact on species identification and it is anticipated that they will have a similar impact on both typing and detection of antituberculosis drugs resistance.

Key words: Mycobacteria, MALDI-TOF MS, identification, sample preparation, databases, future perspectives

Interleukin-17 and Immunity of Ocular infections

Israa Asaad Aziz1,2 Marwan Y. Al-Maqtoofi2, Ahmed A. Burghal2
1 Basrah Teaching Hospital, Basrah Health Department, Ministry of Health, Basrah, Iraq.
2 Department of Biology, College of Science, University of Basrah, Basrah, 61004, Iraq.

The field of Interleukin-17 (IL-17) biology has received more attention during the last decade for evaluating the role of this cytokine to enhance the host defence against microbial infections. IL-17 is essential in controlling microbial colonization through the expeditious innate immune response to pathogens which involves the recruitment of neutrophils and the induction of antimicrobial peptides. IL-17 is synthesized by cell populations predominantly present within epithelial barriers, including specific subsets of Th17 cells and innate lymphoid cells. In this review, we highlight both bacterial and fungal infections in human eyes and the role of IL-17 in host defence in addition to the benefit of using IL-17 for immunotherapy.

Key words: Il-17, bacteria, fungi, immune, innate immunity, adaptive immunity, ocular, eye, immunotherapy

Genotypic resistance profile of ESBL-producing enterobacterales from wound infections in Salem, India

Sureshkumar Mathavi, Gopal Sree Sadhana, Rao A V Raghavendra, Rajan Reena
Department of Microbiology, Vinayaka Mission’s Kirupananda Variyar Medical College & Hospitals, Salem, India.

The Extended Spectrum β-lactamases (ESBLs) have been abruptly increasing in hospital and community settings. The present study aimed to detect ESBL producers from wound infections and to determine the associated ESBL genotypes. Gram-negative bacilli obtained from wound infections for a period of one year from November 2020 to October 2021 were included. Isolates with inhibition zone size ≤ 27 mm for Cefotaxime and ≤ 22 mm to Ceftazidime were subjected to phenotypic confirmation by Vitek 2 ID / AST. Extended spectrum β-lactamase genes OXA-10/11, TEM, SHV & CTX-M were detected by Real Time PCR. The CTX-M enzyme was the most common ESBL genotype observed among Enterobacterales in our study. The co-expression of ESBL genes was observed in clinical isolates of Klebsiella pneumonia and Escherichia coli. CTX-M & TEM genes were observed in 40% of E. coli isolates. All isolates of E. coli with CTX-M & TEM genes were susceptible to carbapenems and amikacin. 8.33% of E. coli isolates with CTX-M genotype alone were resistant to carbapenems and amikacin. 50% of K. pneumoniae isolates with SHV, CTX-M & TEM genes showed resistance to carbapenems, β-lactam/ β-lactamase inhibitor combinations, cefepime and aminoglycosides. In conclusion ESBL associated infections are becoming a public health issue with respect to wide dissemination of ESBL genes and limited therapeutic options.

Key words: wound infections, ESBL Enterobacterales, ESBLs genotypes

Prevalence of serum cryptococcal antigen among HIV infected patients attending a university of Benin Teaching Hospital, Edo state, Nigeria

Okam Chioma Constance1, Morka Emmanuel,2, Morka Blessing Ubulu1,
1 Department of Microbiology, University of Benin, Edo State, Nigeria
2 Department of Microbiology, Delta State University, Abraka, Nigeria

The study was designed to determine the prevalence of serum cryptococcal antigen (CrAg) among HIV-infected patients at the University of Benin Teaching Hospital (UBTH), Edo state, Nigeria. The clinical symptoms, risk factors and past history of some diseases in association with CrAg was determined on 200 HIV-infected patients within the age range of 18 to 71 years, using the cryptococcal antigen lateral flow assay (CrAg LFA). The CD4 count of each patient was determined using the fluorescent-activated cell sorter BD FACS count system. A structured questionnaire was used to gather information on the socio-demographic characteristics, medical and treatment history of patients. Ninety percent of the patients were ART treatment-experienced and 10% were ART naïve. A prevalence of 4.5% cryptococcal antigenemia was observed in the study. The infection rate was higher among the ART naïve patients 5/20 (25%) than in the treatment-experienced group 4/180 (2.2%). Age had no significant association with CrAg (P = 0.731). The association between serum CrAg and CD4 count was found to be significant (P <0.001). More females were CrAg-positive when compared to their male counterparts, but this difference was not statistically significant. History of past diseases such as tuberculosis, hepatitis and diabetes mellitus were not statistically significant among the patients. Exposure to risk factors such as alcohol intake, use of steroids and injection of drugs (drug abuse) was statistically significant, whereas cigarette smoking and exposure to pigeon droppings were insignificant. Although the prevalence of serum CrAg was low in this study, risk factors associated with cryptococcosis must be avoided. In addition, routine screening should be implemented to improve wellbeing and reduce morbidity. In this study we also found out that cryptococcal infection is characteristic to AIDS patients and not HIV patients as generally perceived. Key words: Prevalence cryptococcal antigen, CrAg, serum, AIDS, HIV