A total of 200 samples, 11-80 years of age, were obtained from the outpatient and inpatient Department of Medicine and Chest & TB, SRG hospital and Jhalawar Medical College, Jhalawar were included in the study from June 2012 to June 2013.

Patients with pulmonary tuberculosis, old H/o Tuberculosis, congestive heart failure, pulmonary infarction, and AIDS were excluded from the study.

Two sets of sputum samples were collected after proper instructions regarding collection of sputum sample for which informed consent from patients were taken who were presenting with LRTI (fever, H/o cough, productive sputum, chest pain, anorexia, headache and weight loss) for bacteriological culture into a wide-mouthed sterile containers, transported to the laboratory and processed within 2 hours. The samples were subjected to the following investigations:-

A total of 200 samples were obtained from the outpatient and inpatient Department of Medicine and Chest & TB of which 66% were male and 34% were female [Table/Fig-1].

Seventy seven percent of samples were culture positive for both single pathogen and mixed infection of which 56.5% were male and 20.5% were female as males are more at risk for LRTI. [Table/Fig-2,3 and 4].

Mixed infection is mainly found in admitted patients as they have more chances of nosocomial infection due to stay of patient, also more chances of contact with nosocomial pathogens in the hospital setting.

Klebsiella pneumoniae was the most prevalent pathogen (71/193), followed by Coagulase positive Staphylococci (43/193) [Table/Fig-5].

More resistant pattern was found in CONS showed 61.11% MRSA incidence compared to 41.86% in COPS, [Table/Fig-6] also regarding ESBL production Escherichia coli showed incidence of 36.36% as compared to other gram negative bacilli [Table/Fig-7].

Pseudomonas aeruginosa was the most resistant organism found based on the antibiotic susceptibility pattern while Proteus mirabilis was the most sensitive organism [Table/Fig-8].

The result shows that LRTI was more prevalent in males than in females. Humphrey et al., in their study of prevalence of pneumonia and lower respiratory tract infection reported a high prevalence in males than females [8]. The reason for high risk in males of LRTI as well as COPD is attributable to smoking, use of tobacco, alcohol consumption, etc., causing decreased local immunity in the respiratory tract due to defective mucociliary clearance, mucous plugging, airway collapse, respiratory muscle fatigue and the effect of medications used. Females enrolled in the study comprised largely of housewives, who, being less mobile experienced less exposure to respiratory risk factors.

Maximum number of patients (50.5%) were from 31-40 (24.5%) and 51-60 years (26%) correlated well with the study from Finland, which showed the higher incidence of LRTI in patients over the age of 50 years as the immunity is lower in young and old age group so there is more chances of infection at these age [9]. Studies from different areas reported an aetiological diagnosis between 45% to more than 80% [10] as seen in our study (77%).

Patients in the older age group are more susceptible to gram negative pneumonia because of waning immunity and pulmonary defense mechanisms, underlying chronic diseases such as malnutrition, diabetes mellitus, emphysema, uraemia etc., silent aspiration and increased exposure to antibiotics. Institutional care also makes the patients more susceptible to gram negative pneumonia. In the present study, incidence of mixed infections was 19.5% which is consistent with the fact that incidence of mixed infections does not usually exceed 30% [11]. Identification of polymicrobial infection is very important for treatment strategies. The injury to ciliary motility of epithelial cells occurs due to the entry of infective agent which opens the entry of other infectious agents to infiltrate the lower respiratory tract.

Indian studies have reported higher incidence of gram negative bacilli form several decades among culture positive pneumonia as well as in other form of LRTI [12]. K. pneumoniae, P. aeruginosa and CONS are the commonest organism causing LRTI in inpatients whereas among outpatients, S.aureus is the commonest organism causing LRTI in the present study.

The pathogen causing LRTI, in decreasing order, were Klebsiella pneumoniae (36.79%), Coagulase positive staphylococci (22.28%), Pseudomonas aeruginosa (11.92%), CONS (9.33%), Esch. coli (5.7%), Proteus mirabilis (2.59%) and Candida albicans (1.55%) in this study. This is comparable with a report from Nigeria [13] where commonest organism isolated was K. pneumoniae accounting for 38% of the isolates. A higher prevalence of Klebsiella pneumoniae was found in most studies from India.

Shailaja et al., had earlier reported K. pneumoniae (32.26%) as the most prevalent bacterial isolate [14]. They identified risk or susceptibility to infections with encapsulated organisms such as S. pneumonia and K. pneumoniae to be on higher side. Due to variation in age, season, the type of population at risk, and various other factors the differences in the prevalence of bacterial isolates in different studies were observed elsewhere in India [15].

The sensitivity tests indicated that the isolates were resistant to one or more antibiotics, although generally, a low percentage of the isolates were sensitive to the antibiotic tested. The result of the sensitivity test indicates that Gram-positive and Gram negative isolates showed highest sensitivity to Amikacin, ampicillin + sulbactum, cefotaxime + clavulanic acid, Ceftazidime + clavulanic acid, Ceftriaxone, Imipenam, tetracyclin and netilmycin while high resistance was also recorded for antibiotics such as Ampiciilin, augmentin, ciprofloxacin, chloramphenicol, erythromycin, ofloxacin and gentamycin. This observation poses a serious public health problem and also documented in other studies also [2,16]. The pattern of antibiotic resistance recorded in this study among P. aeruginosa, K. pneumoniae and E. coli isolates is correlated well with the results obtained from Gauchan et al., and Kumari et al., [2,5]. Although P. aeruginosa has been shown to be resistant to many antimicrobioal agents as was found in our study as various mechanism of resistance can be involved including ESBL, metallo beta lactamase (MBL) and ampC beta lactamase production, in its resistance.

More resistant pattern was found in CONS showed 61.11% MRS incidence compared to 41.86% in COPS as now a days more pathogenicity is found to be associated with CONS as they are more involved in serious infections as shown in study of Onanuga A et al., in Nigeria have reported a high prevalence of 69% [17].

In Escherichia coli ESBL production has an incidence of 36.36% as compared to other gram negative bacilli which showed a lower incidence, this was mostly found in other studies as the commonest agent for ESBL production was Escherichia coli, but the number of Escherichia coli was very less in our study so it require further elaboration to confirm. There is an alarmingly high resistance rate was observed to cephalosporins, β lactam-β- lactamase inhibitors, and carbapenem against gram negative microorganisms because of various mechanism of resistance transferred to one bacteria from other bacteria.

The increase in the antibiotic non-susceptible strains of pathogens in recent years could be attributed to their indiscriminate and promiscuous use. This alarming situation developed due to widespread confusion over the aetiology of respiratory infection caused primarily by virus or bacteria which led to the emergence of resistant microorganism. Use of combined therapy & its use for long duration increase the opportunity of resistant strains for acquisition and/or amplification of their resistant mechanisms. In previous era, first line medications were effective and cheaper. With the onset of newer resistance mechanism, newer treatments are developing which are effective but proving too costly to the vast majority of cases living in poor developing countries.

Limitations of this study were lack of availability of facilities for detection of atypical and viral pathogens. Atypical pathogens have been reported in several studies on LRTI’s accounting for 10-15% of the causes of pneumonia as for the diagnosis of atypical pathogens more advanced technologies are required which is not feasible for us.

The level of antibiotic resistance, is a serious public health problem, must bring to light the need for timely and proper diagnosis of the major microbial causes of the respiratory infections, based on antibiotic susceptibility testing in order to administer appropriate therapy of the causative agent. This study revealed that there has been mildly significant change which occurs regarding aetiology of bacterial pathogens involved in LRTI. Judicious use of antibiotics must be done by the clinicians, pharmacist and others who are incorporated in drug delivery system so that we can make a check on the emergence of pathogens acquiring drug resistance to various antibiotics having a role in critical condition or emergency. Also, there is a need first to start empirical therapy and change of antibiotic must be made when we receive the antibiotic susceptibility pattern for that microorganism to hamper the development of resistance mechanism. However resistance to β lactam antibiotics requires further evaluation by more standardized method.