Campylobacter species, particularly
Campylobacter jejuni, have been documented as an important pathogen for causing acute bacterial gastroenteritis in humans. It is projected that around 400–500 million cases of diarrhea are caused by the
Campylobacter sp. each year, worldwide [
1]. In food borne diarrheal illness,
Campylobacter stood second etiologic agent among the enteric pathogens [
2].
Campylobacter are part of normal enteric flora of a wide range of domestic animals and poultry as well as wild animals and birds [
3,
4]. So,
Campylobacter can be transmitted to humans mainly through the consumption of contaminated foods of animal origin, especially undercooked poultry meat, unpasteurized milk and dairy products, as well as by ingestion of other foods that are cross-contaminated by raw poultry meat during food preparation. Though
Campylobacter mediated gastroenteritis is self-limiting; antibiotic therapy is needed to reduce severity of disease. The most common drugs used to control
Campylobacter mediated infections are fluoroquinolones and macrolides. High resistance towards fluoroquinolones has shifted the treatment towards macrolides [
5]. Generally, the prevalence of macrolide resistance among
Campylobacter strains (including both
C. jejuni and
Campylobacter coli) isolated from humans, broilers and cattle in the USA and Canada has been reported at around 10% [
6]. In contrast, more than 40% of
C. coli, isolated from turkeys and swine in the USA, were resistant to this antimicrobial agent [
6]. Likewise, macrolide resistance among
Campylobacter isolates from humans and
C. jejuni isolates from chickens and cattle has been low and stable in most European countries, especially in Scandinavia, but a high prevalence of macrolide resistance, ranging from 15 to 80%, was observed in
C. coli, isolated from chickens and swine [
6,
7]. A tendency for increased macrolide resistance in
Campylobacter has been reported in different developing countries which include Asian countries also [
8,
9]. In northern part of India, the macrolide resistance was 6.1% during 2005 [
10] and reached 22.2% in 2013 [
11] whereas, 0.7% macrolide resistance was reported in eastern India during 2008–2010 [
5] and increased to 4% during 2010–2012 [
12]. Studies from Pakistan stated that macrolide resistance of
Campylobacter was increasing alarmingly—from almost 0% (2002) to 27% (2011–2012) in human isolates [
13,
14].
Campylobacter isolates from Poultry in Pakistan were found more resistant towards macrolide [
14].
Campylobacter isolates from human in Bangladesh were found highly susceptible to macrolides (0.5% during 2005–2008) [
15]. The situation is similar in China. Erythromycin resistance is low in human isolates (1–2%) whereas high in chicken and swine isolates (18% and 37.9 to 54.7%) [
9,
16,
17]. Reports from Sub-Saharan-Africa demonstrated low level of resistance towards macrolides from human
Campylobacter isolates but high level of resistance from cattle isolates [
18‐
20]. On the other hand, high level of macrolide resistance has been reported among human clinical
Campylobacter isolates from developed parts of Africa [
7,
21]. Development and spread of resistance to macrolides among
Campylobacter will significantly limit options for clinical treatment.
Azithromycin, a macrolide is now widely used for the treatment of gastroenteritis and upper respiratory tract infection in India. Our recent study has indicated the growing level of resistance in
Campylobacter isolated in India towards this antibiotic [
12]. This study also indicated that azithromycin resistant
Campylobacter isolates harboured A2075G mutation in 23S rRNA gene and is mainly responsible for high level of azithromycin resistance in Kolkata. During severe infection, reducing the time for detection of the resistance phenotype can be helpful to improve the condition of patient whereas; traditional disk diffusion method consumes at least 48 h to detect azithromycin resistance. We have developed and evaluated a PCR based assay, which is able to discriminate not only
Campylobacter strains resistant to azithromycin but also the sensitive strains to that antibiotic.