Microorganisms Profile and Antibiotics Sensitivity Patterns in the Only Medical Intensive Care Unit in Bosnia and Herzegovina

Abstract

Treatment of critically ill patients entails a great risk for intrahospital infections. Systematic monitoring of intrahospital infection data is a widely used practice in developed countries, while in developing and underdeveloped countries these data are scarce. In Bosnia and Herzegovina, a developing country, precise data cannot be found; hence, this study was created with the aim to monitor the profile and resistance patterns of microorganisms isolated from patients being treated in the only medical intensive care unit (MICU) in the country. This is a retrospective observational study of microorganisms isolated from all patients treated at MICU in the University Clinical Center of Republic of Srpska from January 1 through December 31, 2017. Analysis of all samples was performed using standardized microbiological procedures, while sensitivity to antimicrobials was performed using the disk diffusion method. One thousand six hundred twenty-five samples were taken from 633 critically ill patients and sent off for analysis; 572 were positive for bacteria (35.2%). Gram-negative bacteria were isolated more frequently (65.2%), specifically Acinetobacter baumannii (25.5%), followed by Klebsiella spp. (10.8%). A. baumannii was resistant to all antibiotics except for colistin, to which it was highly sensitive (99.7%). It was moderately sensitive (76%) to rifampicin. Staphylococcus epidermidis, Staphylococcus aureus, and Enterococci were the most prevalent Gram-positive bacteria (15%, 7.3%, and 9.2%, respectively) isolated in this study. It is clear from this study that Gram-negative bacteria are predominant in the newly established MICU. A. baumannii was found to be the most prevalent Gram-negative bacteria, and S. epidermidis was the most prevalent Gram-positive bacteria.

Introduction

Development of intensive care medicine began in the fifties as a result of a large number of patients suffering from respiratory failure caused by the Copenhagen polio epidemic.¹ In spite of rapid progress of medical science, development of nonsurgical intensive care medicine was extremely slow in Bosnia and Herzegovina. One of the main reasons for this is Bosnia and Herzegovina is a postwar country that belongs to a group of low-to-middle income countries.^2,3 Currently, there is only one certified (ISO 9001) medical intensive care unit (MICU) recognized by the Ministry of Health and Social Welfare of Republic of Srpska (Republic of Srpska is one of the two entities in Bosnia and Herzegovina) as a referral center for treatment of nonsurgical critically ill patients.

Infections are frequent in the MICU. They pose a major problem in the treatment of critically ill patients, leading to increased mortality, prolonged intensive care unit (ICU) stay, and an increased financial burden.^4–6 Infections attained in the hospital environment are called intrahospital infections, and they are defined as “infections acquired in a hospital by a patient who was admitted for a reason other than that infection, in whom the infection was not present or intubating at the time of admission, and symptoms should appear at least after 48 hr of admission.”^7,8 Intrahospital infections occur in all hospital departments, but they occur 5–10 times more often in MICU.⁹ The reason for this is that MICU patients are mechanically ventilated, have central venous catheters, urinary catheters, catheters for hemodynamic monitoring, and so on. In addition, MICU patients are often immunocompromised.¹⁰ Wide use of broad-spectrum antibiotics leads to the emergence of antimicrobial resistance, which is an additional burden to the treatment of those who are critically ill. Antimicrobial resistance is on the rise and is a serious threat to global public health.¹¹ The global scenario shows that Gram-positive infections are common in ICUs of developed countries.¹² However, multidrug-resistant Gram-negative bacterial (MDR-GNB) infections dominate the low-to-middle income countries.

Antimicrobial resistance surveillance is the most important tool for assessing the burden of antimicrobial resistance and for providing the necessary antibiogram data, based on which the local, national, and global treatment strategies can be planned. The Global Antimicrobial Resistance Surveillance System (GLASS) was launched in May 2015 by World Health Organization (WHO) to support the standardized approach for antimicrobial resistance data collection, analysis, and sharing on the global level.¹³

In the Western developed countries, there is a large amount of data and observational studies that analyze antimicrobial resistance patterns in MICUs. On the contrary, these data are insufficient in developing and underdeveloped countries. There are a very small number of studies that report on the impact of postwar transition to the profile of microorganisms and antimicrobial resistance patterns in MICUs. More specifically, there are no clear and precise data on microbial maps and antibacterial resistance in the ICUs. Therefore, this study was designed with the aim to report on the microorganism profile as well as antimicrobial resistance patterns of the only MICU in postwar Bosnia and Herzegovina.

Methods

Study design and settings

This is a retrospective observational study of microbial isolates identified in MICU in the University Clinical Center of Republic of Srpska (UCC RS) in a 1 year period (from January 1 through December 31, 2017).

MICU UCC RS serves as a referral center for the territory of 500,000 inhabitants, and is currently the only multidisciplinary MICU in Bosnia and Herzegovina. It should be noted that Bosnia and Herzegovina is a postwar country in transition. The study was approved by the Ethical Committee of UCC RS.

Patient selection, data sources, and endpoints

During 2017, 633 nonsurgical critically ill patients were admitted and treated in MICU. Patients' samples were taken for microbiology analysis and included in this study. The existing medical documentation (electronic database and microbiology laboratory results) was used to obtain relevant data. All samples taken from patients were analyzed at the Department of Microbiology using standardized bacteriological techniques for the identification of bacteria. Identification of bacterial strains was performed on the basis of the characteristic appearance of colonies, determination of physiological and biochemical properties of cultivated colonies, and the automated system VITEK 2. Sensitivity to antibiotics was determined by the disk diffusion method, according to the European Association for Antimicrobial Sensitivity.

All isolated Gram-positive and Gram-negative bacteria from different samples were analyzed: blood, urine, minibronchoalveolar lavage (BAL), liquor, central venous catheter tip (CVC tip), and wound swabs. Bacterial strains resistant to three or more classes of antibiotics were considered multidrug resistant (MDR). Bacterial strains sensitive to only one or two classes of antibiotics were regarded as extensively drug resistant (XDR). Finally, strains resistant to all antibiotics were noted as pandrug resistant (PDR).

Statistics

Data were analyzed using the computer program Microsoft Excel 2013. Continuous variables such as age, sex, Simplified Acute Physiology Score II (SAPS II), and length of stay were expressed as mean ± SD. Other categorical variables were expressed as percentages. The results of the study are presented in the form of text, tables, and graphics.

Results

The total number of patients treated in MICU UCC RS during 2017 is 633 of which 61% were men with a SAPS II score of 65.04. Baseline demographics and clinical characteristics of patients are shown in Table 1.

Table 1.

Characteristics of the Patients Treated in the Medical Intensive Care Unit at University Clinical Center of Republic of Srpska in 2017

Year	2017
No. of patients	633
Age	63.2 ± 0.37
Male	387 (61%)
Mechanically ventilated (invasive + noninvasive)	159 (25.1%)
Vasopressor	244 (38.5%)
SAPS II	65.04 ± 13.61
ICU mortality	148 (26.6%)
Hospital mortality	276 (43.5%)
Length of stay (days)	3.6 ± 0.62
Annual consumption (medicine, equipment, services) (US$)	293,176
Annual per patient consumption (medicine, equipment, services) (US$)	463

ICU, intensive care unit; SAPS II, Simplified Acute Physiology Score II.

During 2017, 1,625 samples of biological material were taken from patients and sent for analysis to the laboratory of the Department of Microbiology. In 572 samples, 35.2% microorganisms were identified. Of the same sample size of 572, 199 (34.79%) were Gram-positive bacteria and 373 (65.2%) were Gram-negative bacteria (Fig. 1).

FIG. 1.

Percentage of Gram-positive (65%) and Gram-negative (35%) isolates in all samples.

In addition, the number of bacteria with high resistance (MDR, XDR, and PDR) was analyzed and presented in Table 2.

Table 2.

Number of Multiresistant Bacteria per Isolate

	Resistance
Microorganism	MDR	XDR	PDR
Acinetobacter baumannii	126 (22%)	19 (3.3%)	1 (BAL) (0.17%)
Pseudomonas aeruginosa	43 (7.5%)	12 (2.1%)	1 (BAL) (0.17%)
Klebsiella pneumoniae	57 (9.9%)	2 (0.35%)	3 (UK) (0.52%)
Vancomycin-resistant enterococcus		5 (0.87%)
Methicillin-resistant Staphylococcus aureus		3 (0.52%)

BAL, bronchoalveolar lavage; MDR, multidrug resistant; PDR, pandrug resistant; XDR, extensively drug resistant.

Positive bacterial isolates from mini-BAL, blood, wound swabs, CVC tip, liquor, and ventricular drainage catheter tip are shown in Table 3.

Table 3.

Number of Microorganisms per Sample of Biological Material

	Sample
Microorganism	BAL	Urinary catheter tip	Tracheostome swab	Groin swab	Throat swab	Nose swab	Ear swab	Pleural punctate	Blood	Urine	Wound swab	CVC tip	Liquor	VDC tip
A. baumannii	96	3	9	0	0	0	0	0	9	9	11	6	2	1
Citrobacter	2	0	0	0	0	0	0	0	0	0	0	0	0	0
Enterobacter spp.	5	1	1	0	0	0	0	0	1	0	1	0	0	0
Enterococcus faecium	0	0	1	0	0	0	0	0	4	4	0	0	0	0
Enterococcus faecalis	3	4	0	0	0	1	0	0	9	22	5	0	0	0
Escherichia coli	12	4	1	0	0	0	0	0	2	28	3	0	0	0
K. pneumoniae	18	3	2	1	0	0	1	0	6	26	2	2	0	0
Staphylococcus coagulase negative	0	0	0	0	0	0	0	0	3	0	0	0	0	0
Proteus mirabilis	11	4	1	2	0	1	0	1	1	10	10	1	0	0
P. aeruginosa	35	0	3	0	0	0	0	0	2	6	5	2	0	0
Pseudomonas spp.	2	0	0	0	0	0	0	0	2	1	0	0	0	0
Serratia	3	0	2	0	0	0	0	0	2	0	0	0	0	0
S. aureus	22	0	3	0	0	1	0	0	10	1	3	0	2	0
Staphylococcus epidermidis	9	1	1	0	0	0	0	0	65	1	4	5	0	0
Streptococcus pneumoniae	10	0	0	0	0	0	0	0	1	0	0	0	0	0
Streptococcus β haemolyticus group A	1	0	0	0	2	0	0	0	0	0	0	0	0	0
Streptococcus β haemolyticus group B	0	0	0	0	0	0	0	0	1	0	0	0	0	0
Total	229 (40%)	20 (3.4%)	24 (4.1%)	3 (0.5%)	2 (0.34%)	3 (0.5%)	1 (0.17%)	1 (0.17%)	116 (20.2%)	108 (18.8%)	44 (7.6%)	16 (2.7%)	4 (0.6%)	1 (0.17%)

CVC tip, central venous catheter tip; VDC tip, ventricular drainage catheter tip.

Sensitivity of isolated Gram-negative and Gram-positive microorganisms to the selected antibiotics is presented in Tables 4 and 5.

Table 4.

Antibiogram of Gram-Negative Microorganisms (% of Sensitivity)

Antibiotic	A. baumannii (n = 146) 25.5%	K. pneumoniae (n = 62) 10.8%	Pseudomonas aeruginosa (n = 58) 10.1%	Escherichia coli (n = 50) 8.7%	P. mirabilis (n = 42) 7.3%	Enterobacter (n = 9) 1.5%
Piperacillin/tazobactam	9.79	57.62	69.04	88.88	92.5	85.71
Imipenem	5.18	89.09	66.03	97.56	77.77	83.33
Meropenem	0	79.06	60	91.66	84.61	80.0
Ceftriaxone	0	25.42	14.2	60.0	28.57	44.4
Cefepime	4.19	37.7	58.62	70.83	80.95	66.6
Gentamicin	0.85	33.33	30.76	73.33	36.11	57.14
Amikacin	4.65	79.62	54.54	91.66	36.11	75.0
Ciprofloxacin	0	39.47	25.64	53.57	29.03	25.0
Trimethoprim/sulfamethoxazole	7.04	26.92	4.08	59.57	15.38	44.4
Rifampicin	76.59	Not tested	Not tested	Not tested	Not tested	Not tested
Colistin	99.29	87.5	59.91	Not tested	0	99.0
Amoxicillin/clavulanic acid	0	18.51	0	48.93	26.82	0

Table 5.

Antibiogram of Gram-Positive Microorganisms (% of Sensitivity)

Antibiotic	S. pneumoniae (n = 11) 1.9%	S. aureus (n = 42) 7.3%	S. epidermidis (n = 86) 15%	Enterococci (n = 53) 9.2%
Ampicillin	20.0	33.3	21.05	67.92
Vancomycin	100	100	100.0	89.36
Amoxicillin/Clavulanic acid	42.85	88.09	32.95	69.23
Ceftriaxone	54.54	88.09	32.95	0
Cefepime	No data	100.0	34.04	0
Azithromycin	42.85	80.0	23.08	0
Clindamycin	100	88.8	14.28	3.44
Tetracycline	25	100.0	20.0	33.3
Doxycycline	No data	No data	No data	No data
Gentamicin	No data	89.47	44.0	25.0
Moxifloxacin	No data	No data	No data	No data
Ciprofloxacin	100	88.57	28.35	22.85
Trimethoprim/sulfamethoxazole	45.45	89.74	38.27	16.27
Rifampicin	66.6	No data	No data	No data
Metronidazole	No data	No data	No data	No data
Chloramphenicol	70	81.48	74.19	No data

Discussion

The most significant finding of this study is that of all the positive isolates in MICU UCC RS, Gram-negative bacteria are the most prevalent (65.2%), with the most predominant being Acinetobacter baumannii (25.5%) and Klebsiella pneumoniae (10.8%). From the level of resistance, Gram-negative bacteria dominate as well. The only PDR bacteria isolated were Gram-negative, specifically K. pneumoniae isolates from urine samples. Most of Gram-negative bacteria were isolated from mini-BAL, followed by isolates from blood samples.

The significance of microbiological monitoring and mapping in ICU is crucial because it helps with decisions regarding the choice of an antimicrobial for empirical treatment. This is based on the profile of the most frequently isolated microorganisms and their sensitivity, until the results of antibiograms become available.

Looking at the microbiology maps of ICUs in the region and countries somewhat similar to Bosnia and Herzegovina, one can conclude that the ratio of Gram-positive to Gram-negative bacteria is similar. A large study performed by Vincent et al. in 75 countries and on 4,947 critically ill infectious patients shows a similar ratio of Gram-negative to Gram-positive bacteria (62% Gram negative).⁵

Analyzing the results of antibiograms in this study (Table 4), A. baumannii was found to be the most prevalent Gram-negative bacteria (25.5%), followed by K. pneumoniae (10.8%) and Pseudomonas aeruginosa (10.1%). In the study by Vincent et al. dominant Gram-negative bacteria were P. aeruginosa, followed by Escherichia coli. This finding does not coincide with our findings. Sader et al. found that the most prevalent Gram-negative bacteria in critically ill patients in the United States were K. pneumoniae and E. coli.^5,14 A possible explanation for this may be the fact that United States is a developed country, while Bosnia and Herzegovina is a developing postwar country. While developed countries have implemented control systems for restrictions in antibiotic prescriptions as well as guidelines for antibiotic use, developing countries are still struggling with these issues. In support of this claim, Moolchandani et al. found that P. aeruginosa and A. baumannii were most often isolated in critically ill patients treated in the ICUs in India.¹⁵

In terms of microbial resistance, the highest degree of resistance is exhibited by the Gram-negative bacteria, specifically A. baumannii. Of those, MDR strains were the highest (22%), followed by XDR strains (3.3%). Most PDR strains came from K. pneumoniae (Table 2).

The results of this study are similar to the results of other studies that analyzed antimicrobial resistance patterns in critically ill patients treated in countries most similar to Bosnia and Herzegovina.¹⁶

Staphylococcus epidermidis (15%), Staphylococcus aureus (7.3%), and Enterococci (9.2%) were the most prevalent Gram-positive bacteria isolated in this study (Table 5). The distribution of Gram-positive bacteria differs from other countries similar to Bosnia and Herzegovina where dominance of Enterococci and S. aureus was detected.¹⁵

By analyzing antibiogram results (sensitivity to certain antibiotics) on isolated microorganisms, it was found that Gram-negative bacteria were mostly sensitive to imipenem (with the exception of A. baumannii). Gram-positive bacteria were mostly sensitive to vancomycin (Table 5). A. baumannii was highly sensitive to colistin (99.29%), while in only 4.19% and 5% of the cases, it showed sensitivity to fourth-generation cephalosporins and carbapenems, respectively. The sensitivity rate of A. baumannii to cephalosporins and carbapenems in other countries similar to Bosnia and Herzegovina is higher compared with the results obtained from this study, 10–20%.^15,17–21 Besides colistin, A. baumannii isolated from patients treated in MICU UCC RS was highly sensitive to rifampicin (76%), which was not mentioned in the literature.

Looking at the number of isolated microorganisms in relation to the sample size taken, it is evident that most microorganisms were isolated from mini-BAL (40%) (Table 3). This is an indirect indicator that infections of the respiratory tract are the most frequent infections in MICU UCC RSS (hospital-acquired pneumonia and ventilator-associated pneumonia). This finding correlates with the data from other studies.^17,18

In conclusion, the significance of this study is that a detailed microbiology map (with an accent to resistance) of the only MICU in Bosnia and Herzegovina was made for the first time. In the newly established MICU UCC RS, the most predominantly isolated bacteria were Gram-negative A. baumannii (∼66%). A. baumannii was also responsible for having the most MDR and XDR strains. K. pneumoniae was the most frequent PDR strain detected in this study. S. aureus was the most dominant Gram-positive microorganism in the study. Methicillin-resistant S. aureus and vancomycin-resistant Enterococcus were the most resistant Gram-positive bacteria, but their resistance patterns were significantly lower compared with Gram-negative strains.

Footnotes

Disclosure Statement

No competing financial interests exist.

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