Aerobic bacteriological proﬁle of acute exacerbations of chronic obstructive pulmonary disease in a tertiary care hospital

COPD is a major cause of morbidity and one of the predominant causes of the death across the world, characterised by a worsening in the patient’s respiratory symptoms which is beyond normal day-to-day variations and eventually leads to a change in the medication. Causative agents for the exacerbation includes factors such as viruses, bacteria and common pollutants. Materials and Methods: This was a retrospective study conducted from sputum samples received from 551 diagnosed cases of AECOPD to the department of microbiology KIMS Hubli. Result: Out of 551 patient’s sputum samples, 335(60.79%) were Males and 216 (39.20%) were females. The total number of culture positive isolates were 51.17%. Among the 282 culture positive isolates, 280 were Mono-microbial (99.3%) and 2 were Polymicrobial (0.7%). Among 282 isolates, Gram Negative Bacilli were 263 (93.26%) and Gram Positive Cocci were 19 (6.74%) Among the total isolates Klebsiella pneumoniae 116 (41.13%) was the predominant isolate followed by Escherichia coli 63 (22.34%), Pseudomonas aeruginosa 28(9.93%), Citrobacter species 26 (9.22%), NFGNB 25 (8.87%), Enterobacter species 5 (1.79%), Staphylococcus aureus 16 (5.67%), CONS 2(0.7%) and Streptococcus pneumoniae 1(0.35%). 51(43.96%) of the Klebsiella pneumoniae isolates were found to be ESBL producers. In case of gram positive organisms, 2(12.5%) were methicillin resistant. Conclusion: This study shows that Klebsiella pneumoniae and Escherichia coli are the commonest organisms associated with acute exacerbation of COPD. A high rate of ESBL producers was observed. the


Introduction
Chronic Obstructive Pulmonary Disease (COPD) is a disease state characterised by airflow limitation and is irreversible, this includes chronic bronchitis and emphysema. 1 Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is characterised by a worsening in the patient's respiratory symptoms which is beyond normal dayto-day variations and eventually leads to a change in the medication. 1 COPD is a major cause of morbidity and one of the predominant causes of the death across the world. 2 According to the World Health Organisation (WHO) estimates in 2004, currently 64 million people have this disease and a whopping 3 million people have died of COPD. 3 By 2030 COPD will become the third leading cause of death worldwide as predicted by WHO. 3 A significant percentage of COPD mortality is contributed by India with about 556,000 out of a world total of 2,748,000 annually accounting to >20%, which is estimated to be amongst the highest in the world. 4 Majority of the information available pertaining to COPD prevalence, morbidity and mortality is mainly from high-income countries. 3 The principal cause of COPD is tobacco smoke which includes second-hand or passive exposure, other risk factors include indoor air pollution like solid fuel used for cooking and heating; outdoor air pollution, occupational dusts and chemicals like vapours, irritants, fumes and also frequent lower respiratory tract infections during childhood. 5 Major pathogenic factor in exacerbations are infectious agents, other contributing factors include air pollution, low temperature and interruption of regular treatment. 6 As per estimations bacterial infections are deemed to be responsible for more than 40% of all exacerbations in India. 7 In AECOPD cases due to infection, three classes of pathogens have been found: respiratory viruses, aerobic gram-positive and gram-negative bacteria, and atypical bacteria. 8 Current data on bacteriology related to AECOPD are mainly obtained from the western countries. 6 The spectrum of organisms in India might be different from those of other countries or regions making it crucial to examine the bacteriology responsible for AECOPD, which is important for the choice of empirical antibiotic treatment. 6 More than 90% of patients with AECOPD receive antibiotic therapy. 2 From time to time bacterial flora of AECOPD keeps changing and depending upon the local bacterial prevalence and resistance pattern the antibiotic is chosen. 9 With better selection of antibiotic for empirical therapy the numbers of failure cases recorded with empirical treatment during AECOPD are reduced. 10 With proper control and prevention of these exacerbations the relentless progress of this disease can be halted and also significantly reduces the mortality and morbidity. 11 The present study was undertaken to know about the aerobic bacteriological profile and the antibiotic sensitivity pattern of AECOPD cases in our hospital.

Materials and Methods
This was a retrospective study based on review of data from patients who were admitted with acute exacerbation of COPD to the Karnataka Institute of Medical Science (K.I.M.S) Hubli, over a period of 1 year from January 2019 to December 2019. Microbiological profile of the aerobic isolates and its antibiotic susceptibility pattern was collected from the maintained records in the department of microbiology and analysis was done.

Culture methods
The samples were processed as per standard microbiological methods. Sputum samples were subjected to Gram's stain and aerobic bacterial culture by inoculation on various culture media like blood agar, chocolate agar, MacConkey agar. The isolates were identified by relevant biochemical tests. The isolates were subjected to antibiotic susceptibility testing on Mueller-Hinton agar plates by Kirby-Bauer disc diffusion method, as per CLSI guidelines. Screening for Methicillin Resistant Staphylococcus Aureus (MRSA) was done using cefoxitin (30 µg) disc. Resistance to ceftazidime (30 µg) disk was used as a screening method for detection of Extended Spectrum Beta Lactamase (ESBL) confirmed by double disk synergy test.
CONS all the isolates were sensitive to linezolid, erythromycin, clindamycin, levofloxacin. 50% isolates were resistant to azithromycin and ciprofloxacin.
The sensitivity pattern for gram positive cocci is shown in the Table 4.

Discussion
COPD is a major cause of morbidity and mortality throughout the world. Early induction of empirical antibiotics can improve the outcome and reduce mortality. Since culture techniques are time consuming, it is better to know the pattern of bacterial flora and their sensitivity in a particular geographic area.
The result of this study provides an overview of current microbiology and aerobic bacteriological profile of northern Karnataka.

Age and gender distribution
It was observed that acute exacerbation of COPD is prevalent in 41-70 years of age. However among them 40-50 year of age group constitute 23.41%, 51-60 years constitute 19.6%,61-70 years constitute 17.24%. AECOPD was common in advanced age group as respiratory tract is more susceptible due to impairment of immunological defence mechanisms, associated co morbid illness, increased duration of seasonal variation and tobacco smoking. 12 Male(60.79%) predominance was seen in this study population compared to female (39.21%). In our country, Males are more exposed to outside environment because of their more mobility compared to females. Moreover smoking habits are more pronounced in male that constitute one of the predisposing factor for development of COPD.
Smoking and air pollution are responsible for decreased muco ciliary clearance and innate immunity. 16 It leads to increased bacterial colonisation that can give rise to increased airway inflammation and thus exacerbation. A prospective study was made by Madhavi et al, 17 who had 79% males and 21% females.

Bacteriological profiles and sensitivity pattern
Growth of pathogenic organism was obtained in was obtained in 51.17% of sputum samples. Culture positivity depends on nature of sputum, transportation time and number of organisms present in the sample.
Gram positive and Gram negative organism was isolated in 7% and 93% of study population.    Among GNB Klebsiella pneumoniae 116(41.13%) was the predominant organism followed by Escherichia coli 63(22.34%), Pseudomonas aeruginosa 28(9.93%), Citrobacter species 26(9.22%), NFGNB 25(8.87%), Enterobacter 5(1.79%), and among Gram positive organisms Staphylococcus aureus 16(5.67%) was the predominant isolate followed by CONS 2(0.7%), Streptococcus pneumoniae 1(0.35%). The bacterial isolates depends on various factors like prevalence of bacteria in the hospital environment, in the community, antibiotic prophylaxis and severity of exacerbation. This finding is contrary to other studies reported by Seshagiri Rao, et al. 18 in 2017 who had found Streptococcus pneumoniae (28%) while Anand Patel, et al. 18 had found Klebsiella pneumoniae (59%) as commonest isolate. But otherwise their microbial profile is almost similar to the bacteriological profile noted in our study. In Kaliparambil Sugathan Roshni et al. 19 gram negative bacteria were isolated commonly in COPD patients. In contrary in a study by Rao D S, 20 Streptococcus pneumoniae was the most common organism isolated.
As regards the sensitivity rates of antibiotics regardless of the type of organism, it was found that the most sensitive antibiotic in the whole study was imipenem, amikacin and piperacillin tazobactam and resistance rate was high in case of ciprofloxacin and amoxicillin clavulanic acid. Erkan et al, 21 noted the poor efficacy of penicillin, ampicillin, amoxicillin-clavulanic acid, tetracycline, and erythromycin against most prevalent respiratory pathogens in acute exacerbation of COPD. Their results agree with the low sensitivity rates of these antibiotics in this study.
In this study 51(43.96%) of the Klebsiella pneumoniae isolates and 45(71.43%) Escherichia coli isolates were found to be ESBL producers and 12.5% of Staphylococcus aureus species isolated were methicillin resistant. Erkan et al 21 noted the poor efficacy of penicillin, ampicillin, amoxicillin-clavulanic acid, tetracycline, and erythromycin against most prevalent respiratory pathogens in acute exacerbation of COPD. Their results agree with the low sensitivity rates of these antibiotics in this study (5.5% for amoxicillin-clavulanic acid, 3.6% for erythromycin, 2.75% for tetracycline, 1.8% for penicillin, and 0.9% for ampicillin).

Conclusion
This study shows that Klebsiella pneumoniae and Escherichia coli are the predominant organisms associated with AECOPD. Overall the gram negative bacilli sensitive to most of the commonly used antibiotics. High rates of ESBL producers was also observed. Studies like this will help in better selection of antibiotics for empirical therapy and prevent the mortality and morbidity due to acute exacerbation of chronic obstructive disease.

Source of Funding
None.

Conflict of Interest
None.