Vulvovaginal candidiasis and antifungal susceptibility pattern of isolated Candida spp. among women in Aden Governorate, Yemen

Abstract

Background

Vulvovaginal Candidiasis is a complicated inflammatory infectious disease of the female genital tract caused by the genus Candida. Most studies dealing with VVC in Yemen did not involve both risk factors and antifungal sensitivity. So, this study was performed to evaluate risk factors contributing to VVC and to evaluate the antifungal susceptibility patterns of Candida spp. among women in Aden, Yemen.

Methods

One hundred and two women were enrolled in this cross-sectional study. Two high vaginal swabs were collected, tested microscopically, and inoculated in SDA. A chromogenic medium was used to identify and differentiate Candida species. Six available antifungal agents were used for sensitivity testing included: Itraconazole, Fluconazole, Ketoconazole, Clotrimazole, Nystatin and Miconazole by disc diffusion method. The data was finally analyzed by using SPSS software (Version 21).

Results

A total of 102 women were included in this study. The mean age was 27.36 ± 7.7 years, with a range of 16–47 years. The overall frequency of VV among women was 39.2%. The highest rate was 44.9% (22/49) in the age group < 25 years. Five species of Candida were isolated, with C. albicans being the most frequent (55%), followed by C. krusei (17.5%), C. glabrata (12.5%), C. tropicalis (10%) and C. parapsilosis (5%). Symptom severity was significantly associated with VVC (p = 0.0001), whereas the association with pregnancy did not reach statistical significance (p = 0.066). In terms of antifungal susceptibility testing, the overall resistance was 20% to Clotrimazole, 15% to Nystatin, 7.5% to both Ketoconazole and Miconazole and the lowest resistance rate (2.5%) was to Fluconazole. All five isolated species were 100% sensitive to Itraconazole.

Conclusion

It can be concluded from this study that the overall frequency of VVC among women in Aden-Yemen is higher than that reported among Yemeni women, while slightly lower than that reported globally. The infection was high among women in the age group < 25 years. C. albicans and C. krusei were the most frequent species. The pregnancy may increase the risk of VVC. Resistance was found to Clotrimazole, Nystatin, Ketoconazole, Miconazole, and Fluconazole, while no resistance was detected to Itraconazole among those species. The resistance among non-albicans Candida (NAC) species has increased.

Background

Candida species (Candida spp.) are yeast-like fungi that are considered the main causative agents of fungal infections worldwide [1]. They are usually harmless in immunocompetent individuals, where about 20–50% of asymptomatic women have Candida spp as flora in their lower genital tract. However, they are considered opportunistic pathogens when the immune system is lowered or mucosal barriers are disrupted. So, they can invade host tissues and cause diseases [2]. They can cause oral and genital candidiasis (thrush), esophagitis, and chronic mucocutaneous candidiasis [3]. Disseminated infections such as Candidemia, endophthalmitis and endocarditis may occur in immunocompromised patients [4].

Vulvovaginal Candidiasis (VVC) is a complicated inflammatory infectious disease of the female genital tract caused by the genus Candida [5]. This type of candidiasis is a global health concern due to its association with significant healthcare costs, sexually transmitted diseases (STDs), and ascending vaginal infections [6]. VVC occurs at least once during the lifetime of about 30–50% of women [7]. Numerous risk factors may increase the severity and complications of VVC, including changes in the immune system, elevated vaginal glycogen production, increased estrogen levels, asymptomatic colonization during pregnancy, and pregnancy itself [8].

There are several species belong to genus Candida which can be divided into Candida albicans and non-albicans Candida (NAC). The latter includes Candida glabrata, Candida krusei, Candida tropicalis, Candida parapsilosis, Candida dubliniensis, and Candida lusitaniae. The majority of candidiasis are caused by C.albicans [9, 10].

The diagnosis of VVC is made by direct microscopy and by growing the fungi on Sabouraud’s dextrose agar (SDA) at 30 °C. Along with inoculation in chromogenic media, the species are differentiated by morphologic characteristics on culture media, carbohydrate fermentation, and germ tubes, and the ability of some of them to produce hyphae [11].

The antifungals-resistant species of Candida have emerged, leading to systemic candidiasis [12]. Most species appear resistant at least to one or more antifungal drugs (9). Certain NAC species, such as C. krusei, are naturally (intrinsically) resistant to fluconazole (FCZ) [13]. Azoles are among the commonly used antifungals that inhibit the fungal cell membrane by interfering with the conversion of lanosterol to ergosterol [3]. Resistance in Candida spp. to azoles, such as FCZ, occurs either through efflux pumps that expel the drug from the cell or by modification of the target enzyme (14α-demethylase) responsible for ergosterol production [13]. NAC species also protect themselves against antifungals through biofilm formation [1]. These resistance mechanisms complicate the treatment of Candida infections, leading to recurrent fungal infections and severe complications. The increasing antifungal resistance rates represent a burden, necessitating the use of alternative antifungals and the development of new drugs [6, 9].

In Yemen, several studies have detected the prevalence of VVC at 70.0% in Hajjah, 61.5% in Ibb [14, 15], 51.6% in Sana’a, and 20.8% in Aden [16]. Most previous studies focused on determining the prevalence of VVC, while they did not involve both risk factors and antifungal sensitivity. Therefore, this study was conducted to evaluate the risk factors contributing to VVC and to evaluate the antifungal susceptibility patterns of Candida spp. among women in Aden, Yemen.

Methods

Study design and population

This cross-sectional study was conducted from January 1 to the end of March 2023 at the Gynecology and Obstetrics (G&O) clinic in Al-Sadaqa Teaching Hospital, Aden, Yemen. One hundred and two adult women were involved in the study. The inclusion criteria were women of reproductive age (15–50 years) who had vulvovaginal symptoms such as vaginal discharge, itching, irritation, or discomfort, and who consented to participate in the study. Both pregnant and non-pregnant women were included. The exclusion criteria were women younger than 15 years or older than 50 years, women without vulvovaginal symptoms, those with known immunocompromising conditions (e.g., HIV), and women who had used antifungal or antibiotic treatments within the two weeks prior to sample collection, as these could affect the detection of Candida species. Additionally, women with systemic infections or chronic underlying medical conditions that could confound the study outcomes were also excluded.

Data collection

Previously designed questionnaires with some modifications were used in our research. It included sociodemographic data, such as age, economic status, and level of education. It also gathered clinical data such as severity of symptoms, vaginal discharge, and recurrent infection, as well as questions about risk factors related to VVC infection, including the presence or absence of pregnancy and diabetes. Additionally, the questionnaire included questions on contraceptive use, antibacterial and antifungal treatments, and the direction of genital wiping after toilet use [17].

Specimen collection

Clinically investigated symptoms and vaginal abnormalities were recorded by gynecologists. Before the collection of samples, the objectives of the study were explained to all participants, who were then asked to provide their consent. Two high vaginal swabs were collected from each participant by a gynecological specialist. Swabs were transported to the laboratory at the Faculty of Medicine & Health Sciences, Aden University, within 30 minutes. The first swab was used for direct microscopy to detect yeast cells or pseudohyphae, while the second swab was used for culture.

Study procedures

These swabs were tested by microscopy and confirmed by inoculation in SDA. Chromogenic medium (HiMedia-M1297A) was used to identify and differentiate the Candida species. The inoculated media were incubated at 35 °C for 24–48 hours, and species were identified based on colony morphology and biochemical tests such as carbohydrate fermentation and other tests as the germ tube test for C. albicans. Colonies of Candida albicans appeared light green on chromogenic media, while other NAC species exhibited distinct colors: C. krusei presented with rough, pink colonies, C. glabrata appeared as small white colonies, and C. tropicalis was identified by its dark blue colonies.

Diagnostic criteria

Women were considered to have vulvovaginal candidiasis if they had compatible symptoms and either (i) direct microscopy of a vaginal swab (saline/10% KOH wet mount) showed budding yeast and/or pseudohyphae, or (ii) culture on Sabouraud dextrose agar at 30 °C with subsequent subculture on chromogenic medium at 35 °C yielded growth of Candida spp. within 24–48 h. Species identification was performed using chromogenic characteristics and conventional tests (germ tube, carbohydrate fermentation). When microscopy and culture were discordant, the culture result was used for species identification and susceptibility reporting.

Antifungal susceptibility testing

The disc diffusion method for antifungal susceptibility testing was employed as a screening tool using Mueller-Hinton agar supplemented with 2% glucose and 0.5 μg/mL methylene blue. Six available antifungal agents were used for sensitivity testing, including Itraconazole (ICZ, 10 μg), Fluconazole (25 μg), Ketoconazole (KCZ, 15 μg), Clotrimazole (CTZ, 10 μg), Nystatin (NS, 100 IU), and Miconazole (MCZ, 10 μg) (Sigma-Aldrich Quimica, Madrid, Spain). Fluconazole susceptibility was not tested for C. krusei due to its intrinsic resistance. The inoculated plates were incubated at 35 °C for 24 hours. Antifungal susceptibility results were documented by measuring the zone of inhibition around the antifungal discs. Resistance was determined based on the diameter of the inhibition zones, which were measured according to Clinical and Laboratory Standards Institute (CLSI) protocol. The breakpoints for antifungal agents used for Candida spp. depended on the species, with the following standards: ICZ (S ≥ 23 mm; I = 14–22 mm; R < 13 mm); FCZ (S ≥ 17 mm; I = 14–16 mm; R ≤ 13 mm); KCZ (S ≥ 20 mm; I = 10–19 mm; R < 10 mm); CTZ (S ≥ 20 mm; I = 10–19 mm; R < 10 mm); NS (S ≥ 15 mm; I = 10–14 mm; R < 10 mm); and MCZ (S ≥ 22 mm; I = 14–21 mm; R ≤ 13 mm) [18].

Data analysis

The data were analyzed using SPSS software (Version 21). Quantitative data were expressed as mean ± standard deviation (SD) because they followed a normal distribution, while percentages were used to express qualitative data. The association between two or more qualitative variables and the detection of p-values were determined by the chi-square (χ²) test. All p-values are two-tailed, and p < 0.05 was considered statistically significant.

Results

A total of 102 women were included in this study. The total mean age ± SD was 27.36 ± 7.7 years, with a range of 16–47 years (Table 1).

Table 1.

Distribution of studied group according to their ages

Age groups/years	studied group
	No.	%
< 25	49	48.0
25–34	34	33.3
> 34	19	18.6
Total	102	100

The overall frequency of VVC among women was 39.2% (40/102). The highest rate was 44.9% (22/49) in age group < 25 years (Table 2).

Table 2.

The frequency of VVC among women according to their ages in Aden, Yemen

Age groups/years	Vulvovaginal candidiasis
	Positive		Negative		Total
	No.	%	No.	%	No.	%
< 25	22	44.9	27	55.1	49	48.0
25–34	11	32.4	23	67.6	34	33.3
> 34	7	36.8	12	63.2	19	18.6
Total	40	39.2	62	60.8	102	100

Five species of Candida were isolated, with C. albicans being the most frequent, found in 55% of the women, followed by C. krusei (17.5%), C. glabrata (12.5%), C. tropicalis (10%), and C. parapsilosis (5%) (Fig. 1).

Fig. 1.

Distribution of Candida species isolated from women with vulvovaginal candidiasis in Aden, Yemen

In terms of symptom severity, women with severe symptoms of VVC were more likely to have positive Candida cultures compared to those with mild symptoms. Of the 80 women who had severe symptoms, 48.4% (39/80) were diagnosed with VVC, whereas only 4.5% (1/22) of women with mild symptoms had a positive VVC infection. This suggests a significant association between symptom severity and the presence of VVC (p = 0.0001). There was a non-statistically significant trend toward an association between VVC and pregnancy (p = 0.066) (Table 3).

Table 3.

Association of severity of the symptoms, vaginal discharge and recurrence of infections and some risk factors with VVC among women in Aden, Yemen

Variable	VVC +ve		p	Variable	VVC +ve		p-value
	No.	%			No.	%
Pregnancy				Wiping direction in toilet
Pregnant (n = 38)	19	50.0	0.066	Forward wiping (n = 68)	26	38.2	0.469
Non-pregnant (n = 64)	21	32.8		Backward wiping (n = 34)	14	40.2
Symptoms				Use antibiotics
Severe (n = 80)	40	49.4	0.0001	Yes (n = 13)	4	30.8	0.364
Mild (n = 22)	1	4.5		No (n = 89)	36	40.4
Recurrent infection				Use antifungal
Yes (n = 57)	22	38.6	0.523	Yes (n = 13)	4	30.8	0.364
No (n = 45)	18	40.0		No (n = 89)	36	40.4
Education level				Use contraceptive
Illiterate (n = 13)	2	15.4		Yes (n = 5)	1	20.0	0.346
Primary (n = 41)	20	48.8	0.656	No (n = 97)	39	40.2
Secondary (n = 32)	12	37.5		Diabetics
University(n = 16)	6	37.5		Yes (n = 1)	1	100.0	0.392
Income				No (n = 101)	39	38.6
< 66$(n = 64)	25	39.1	0.565
> 66$(n = 38)	15	39.5
Vaginal discharge
Presence (n = 101)	40	39.6	0.608
Absence (n = 1)	0	0.0

The resistance of Candida spp. to antifungal drugs was 20% for CTZ, followed by 15% for NS, and 7.5% to each of KCZ and MCZ. The lowest resistance rate was 2.5% for FCZ and no resistance was observed to itraconazole (ICZ, 0%) (Fig. 2).

Fig. 2.

Overall antifungal susceptibility of Candida isolates from women with vulvovaginal candidiasis in Aden, Yemen. The horizontal bar chart shows the proportions of isolates categorized as resistant and sensitive to six antifungal agents: fluconazole (FCZ), ketoconazole (KCZ), itraconazole (ICZ), clotrimazole (CTZ), nystatin (ns), and miconazole (MCZ)

According to antifungal resistance rates among Candida spp, C. glabrata exhibited the strongest resistance to CTZ at a rate of 60%, followed by 50% of C. parapsilosis. Additionally, 25% of C. tropicalis exhibited resistance to NS, whereas 20% of C. glabrata showed resistance. Fifty percent of C. parapsilosis exhibited resistance to KCZ and 14.3% of C. krusei was resistant to MCZ. Among species tested for fluconazole, all isolates were susceptible except C. albicans (4.5%); fluconazole was not tested for C. krusei (Fig. 3).

Fig. 3.

Antifungal susceptibility patterns of Candida species isolated from women with vulvovaginal candidiasis in Aden, Yemen. Each panel displays the proportion of isolates categorized as susceptible, intermediate, or resistant to six antifungal agents: fluconazole, ketoconazole, itraconazole, clotrimazole, nystatin, and miconazole. Species-specific responses are shown for: (A) Candida albicans, (B) Candida krusei (fluconazole not tested; intrinsic resistance), (C) Candida glabrata, (D) Candida tropicalis, and (E) Candida parapsilosis

Discussion

The overall prevalence of VVC was 39.2% in this study. This result is consistent with findings from Iran, where the prevalence was 39.76% [19]. Nearly similar rates were 41.4% and 41.8% noticed in Ethiopia and India [6, 20]. In contrast, other studies revealed higher rates than ours such as 45% in Somalia [21], 50.2% and 50.4% in Egypt [10, 22], 54.66% in Iraq [17], 55% and 61.8% in Iran [19, 23]. One of the highest percentage rates was 84.5% in Nigeria [24]. On the other hand, lower rates were observed such as 5.44% in Brazil [25], 14.0% in Nigeria [26], 22.21% in Saudi Arabia [27], 24% in Libya [28], 28.3% in Iran [29], in Yemen 20.8% [16], 30% in Brazil [30] and 31% in India [31]. These variations could be explained by the personnel behaviors, hygiene, and socioeconomic status of women in different countries [32].

According to the age group, the highest prevalence rate of VVC was 44.9% among women aged < 25 years. A similar finding was shown in a study by Pavani et al., in which women in the age group 18–25 years had the highest VVC rate [33]. Several studies revealed different results as 20–30 years [19, 26, 34–36], 21–25 years [37], 23–26 years [38], 26–30 years [27], 28–37 [14], 25–34 years [16] and 30–34 years [17]. Overgrowth of Candida yeasts and increase of VVC among women within this range of age due to an increase of sexual activity among women. In addition to the protection routes that might be used during menstrual loss, wearing of tight clothing, and directions wiping for vagina [39].

In the current study, among five Candida species, C. albicans was the most commonly isolated, and C. krusei was the commonest one of NAC, followed by C. glabrata, C. tropicalis and C. parapsilosis. Bitew & Abebaw, found similar observations where C. albicans and C. krusei were predominant among C. albicans and non-albicans species respectively [6]. On the contrary, the finding was recorded by Ghaddar et al. and Waikhom et al. where C. glabrata was the most isolated yeast, followed by C. albicans [40, 41]. Different reports were recorded by other authors as C. albicans and C. glabrata [17, 21, 29, 42–48], C. albicans and C. tropicalis [23, 31, 49], C. albicans, C. tropicalis and C. krusei [9], C. albicans and C. lusitaniae [10], C. albicans and C. parapsilosis [50] and C. albicans and C. lusitaniae [51]. The sensitivity of techniques used for identifying the Candida species and the different geographical distribution of those species among those populations could be explained by the differences in global distribution [52, 53].

About the severity of the symptoms and risk factor, there was a significant association between the VVC and severe symptoms (p = 0.0001). The association was also significant between VVC and pregnancy (p = 0.066). Al-akeel et al. and Abdullah showed a significant association between pregnancy and positive culture (p = 0.047) [17, 27]. Siddiqui reported different data [54]. Hormonal variations may contribute to increasing VVC among pregnant women [32].

In terms of susceptibility testing for antifungal drugs in the present data, the overall resistance among Candida spp. was 20% of CTZ (10 µg), followed by 15%NS (100 IU), 7.5% to KCZ (15 µg) and MCZ (10 µg) each and lowest rate of resistance was 2.5% for FCZ (25 µg). Three researchers reported that resistance to CTZ was 24.2%, 24.6%, and 59.3% [9, 14, 55].

According to the present findings, the highest resistance rate to CTZ among Candida spp. was for C. glabrata 60%, followed by C. parapsilosis 50%. Slightly similar results were reported by Khan et al. who showed that 62.5% of C. glabrata was resistant to CTZ [9]. Deorukhkar and Saini reported that 50% of C. parapsilosis to CTZ [56]. In contrast, Das et al., found that 50% of C. krusei was CTZ resistant [55].

Khan et al. reported that the resistance rate to NS was 58.3% [9]. Two studies revealed that 9.3% of isolates were NS resistant [41, 50]. Lower rate was noticed by Edrees et al. where the resistance rate of those yeasts to NS was 5.2% [14]. In the present results, 25% C. tropicalis was resistant to NS, followed by 20% C. glabrata. A study by Khan et al. found that 68.7% of C. glabrata and 38.8% C. tropicalis were resistant to NS [9]. Other studies showed that there were no isolates resistant to NS [45, 57].

Two studies from Yemen and India recorded that 26.87% and 35.3% of isolates were KCZ resistant, respectively [14, 20]. A lower percentage (3.4%) was detected in Brazil [30], while no KCZ resistant isolates were reported in Saudi Arabia and India [27, 45]. In the obtained data, 50% of C. parapsilosis was resistant to KCZ. Different rate was reported by Das et al., in which 30% of C. krusei was resistant to KCZ [55]. No KCZ resistant isolates were reported in Saudi Arabia and India [27, 45].

Researcher from Vietnam observed that 13.0% of isolates were resistant to MCZ [50]. Another study showed that 63% of isolates were MCZ resistant [56]. Our findings revealed that 14.3% of C. krusei was resistant to MCZ. Sasikala & Udayasri detected no resistance to MCZ among all isolates [45].

Somewhat similar to our data, Dharmik et al. detected that 2.8% of Candida species were resistant to FCZ [56]. Goulart et al. showed a lower rate of resistance, which was 1.7% [30]. Several studies demonstrated different percentages of resistance rates to FCZ such as 8.7% [50], 8.96% [14], 15.6% [55], 17.2% [6], 25% [54], 42% [58], and 62% [9]. A study in Iran found, there was not any isolate resistant to FCZ [29]. All species were sensitive to FCZ except C. albicans, where the rate of resistance was 4.5% in this study. Al-akeel et al. revealed that 5% of C. albicans was FCZ resistant [27]. A study in Egypt found that 3.1% of C. albicans was resistant [10]. Bitew and Abebaw found that 2% of C. albicans was resistant to FCZ [6]. Two studies from Iran and Kuwait revealed that all species were 100% sensitive to FCZ [29, 42]. Different findings were noticed by Deorukhkar and Saini, where the resistance to FCZ among Candida spp. were 29.5%, 27.3, and 25% for C. tropicalis, C. glabrata and C. kefyr, respectively [56]. Other studies showed that 71.43, and 100% of C. krusei were resistant to FCZ [9, 45, 57]. C. krusei was naturally resistant to FCZ [13].

In the current study, all five isolated species were 100% sensitive to ICZ (10 µg). This contradicts the studies from different regions globally [9, 14, 46, 48, 58, 59]. Our study noticed that the NAC is more resistant to most antifungal agents than C. albicans. The formation of biofilm plays a role in the difference in the ability of Candida species to resist antifungal drugs [60].

Although this study was conducted in a specific geographic area, the findings provide valuable insight into antifungal resistance patterns in a resource-limited setting. Candida species distribution and drug susceptibility vary significantly by region, and data from underrepresented populations such as Yemeni women are essential to global surveillance efforts. Reporting local resistance patterns contributes to the broader understanding of emerging antifungal resistance and supports evidence-based strategies for diagnosis and treatment, both regionally and internationally.

Limitations of the study

This study has several limitations. First, the sample size was relatively small, which may limit the generalizability of the findings to a broader population. A larger sample size would provide more robust data on the prevalence of VVC and antifungal resistance patterns. Second, this study relied on conventional methods, including chromogenic agar, for preliminary identification of Candida spp., which cannot definitively distinguish all species. More advanced techniques, such as polymerase chain reaction (PCR), would improve species-level accuracy and diagnostic precision. Third, the cross-sectional design of the study limits the ability to establish causality between risk factors and the development of VVC. Fourth, although antifungal susceptibility testing was conducted using standardized disc diffusion techniques, the CLSI broth microdilution method (M27–A3/S4) was not utilized due to resource constraints. This method is considered the gold standard and may offer more precise and reproducible results. Future studies should incorporate this approach where feasible to strengthen susceptibility data. Finally, the study did not investigate the clinical outcomes of treatment, which would provide valuable insights into the effectiveness of antifungal therapy in this population.

Conclusions

It can be concluded from this study that the overall frequency of VVC among women in Aden, Yemen, is higher than that reported among Yemeni women, while it is slightly lower than most reported globally. The infection was high among women in the age group < 25 years. C. albicans and C. krusei were the most frequent species. Pregnancy can increase the risk of VVC. Among the five antifungal agents, resistance was found against CTZ, NS, KCZ, MCZ, and FCZ, while no resistance to ICZ was detected among those species. The resistance has increased among NAC species.

Abbreviations

Candida spp

Candida species

VVC

Vulvovaginal Candidiasis

STDs

Sexually transmitted diseases

NAC

Non-albicans Candida

C. albicans

Candida albicans

C. glabrata

Candida glabrata

C. krusei

Candida krusei

C. tropicalis

Candida tropicalis

C. parapsilosis

Candida parapsilosis

C. dubliniensis

Candida dubliniensis

C. lusitaniae

Candida lusitaniae

G&O

Gynecology & Obstetrics

SDA

Sabouraud’s dextrose agar

FCZ

25 µg: Fluconazole

KCZ

15 µg: Ketoconazole

CTZ

10 µg: Clotrimazole

ICZ

10 µg: Itraconazole

NS

100 IU: Nystatin

MCZ

10 µg: Miconazole

SD

Standard deviation

χ2

Chi-square

CLSI

Clinical and Laboratory Standards Institute

NA

Not available

Fig

Figure

n

number

S

Sensitive

I

Intermediate

R

Resistant

Author contributions

A.N.M.G made final revision of the manuscript, M.A.A.A collected and analyzed the samples and wrote the introduction and methodology sections, and N.M.A analyzed the data and wrote the results (prepared figures and tables). All authors contributed the same.

Funding

No funding.

Data availability

This article included all necessary data and if there is further data needed, it can be made available by the authors at any time.

Declarations

Ethics approval and consent to participate

The ethical approval of this study was obtained from the Ethics Committee of College of Medicine and Health Science at University of Science and technology; MEC No. (MEC/AD07) according to standards of Helsinki Declaration. In addition, written informed consent was obtained from each woman before performing any procedure.

Consent for publication

Not applicable.

Author information

A.N.M.G is an Assistant Professor in Diagnostic and Molecular Microbiology Department of Health Sciences, Faculty of Medicine and Health Sciences, University of Science and Technology, Aden, Yemen, M.A.A.A is an Associate Professor in Microbiology and Immunology Department of Medical Laboratory, Faculty of Medicine and Health Sciences, Aden University, Aden, Yemen, N.M.A has an MSC degree in Medical Microbiology, Department of Medical Microbiology and Clinical Immunology, Faculty of Medicine and Health Sciences, Sana’a University, Sana’a, Yemen.

Competing interests

The authors declare no competing interests.