INTRODUCTION

Antimicrobial resistance, a process between microorganisms and antimicrobials where the drug loses efficacy, becoming a complex challenge for public health, this natural phenomenon is currently accelerated by the misuse of antimicrobials^1,2.

Currently, it is common to identify microbiological isolates in the hospital environment and outside of it, with resistance levels ranging from multidrug-resistant (MDR), extremely resistant (XDR), and even pan-resistant, in which no type of antimicrobial has an effect. With respect to the latest estimates for the Prevention and Control of Diseases of the United States (CDC), these microorganisms have a high economic impact of 35 million additional dollars in medical expenses; in turn, they are the cause of more than 2 million infections and 23,000 deaths annually in the US³.

In the CCUs, there is a diversity of microorganisms that are exposed to different antiseptic agents, which causes them to generate a specific resistance for each antimicrobial group. In these units, patients are found in a vulnerable state due to their homeostatic and immunological instability, which makes them more easily infected by these microorganisms⁴.

Antimicrobial resistance is understood as the mechanisms that can produce various types of microorganisms in response to the use of drugs that are used for the treatment and prophylaxis of diseases caused by these. This is increased with its indiscriminate use by the population⁵.

There are two types of resistance, intrinsic, specific properties of bacteria, whose same species are invariability resitant to some groups of antibiotics. On the other hand, the acquired type is revealed in therapeutic failures in patients infected with these bacterial strains that, through certain mechanisms,become resitant to the drug that was usually sensitive⁶.

Worldwide, as in India, it was shown that the most frequent species isolated in critical care units were Staphylococcus aureus and Klebsiella pneumoniae, both resistant to cephalosporins. In addition, more than half of the S. aureus found were S. aureus resistant to methicillin (MRSA), and none of them were resistant to linezolid and vancomyc⁷.

A study, conducted at the Latin American level, reported that the most frequently isolated bacteria in critical care units were Escherichia coli and K. pneumoniae resistant to ampicillin, cefazolin, and piperacillin/tazobactam⁸.

In 2014, in a social security hospital in Chiclayo, it was shown that the most frequently isolated bacteria in the Intensive Care Unit (ICU) were K. pneumoniae, 27.3%; Pseudomonas aeruginosa, 13.6% and E. coli, 11.5% resistant to cephalosporins and sensitive to carbapenems and aminoglycosides⁹.

The objective of this study was to describe the microbiological profile of the microorganisms isolated from patients in the critical care units of a hospital in the Lambayeque region in 2019-2020. This research allowed us to have quality control for treating infections that occur, unlike other hospitals in the region.

METHODS

RESULTS

The study included 332 microbiological records of patients treated in critical care units of the HRL, during 2019 and 2020. The study population was characterized by a median age of 50 years, with an interquartile range (IQR) of 28 to 66. Likewise, the median age in the Pediatric Special Care Unit (PCU) and ICU was one year (IQR= 1 - 8) and 51 years (IQR= 36 - 70), respectively.

Table 1, shows the demographic characteristics of the study population, where there is a predominance of the male sex (55.1%) and the age group of 18 to 59 years (57.2%).

While inTable 2, the laboratory characteristics of the study population, the most frequently obtained samples with positive culture were from the respiratory tract (TR= Bronchial secretion, Tracheal aspirate, Bronchoalveolar lavage) 57.8%; for urine culture, it was 22.9%, and the service of origin was ICU 91.3%

AndTable 3shows the microbiological characteristics of the study population; approximately 50.0% of the E. coli and K. pneumoniae regardless of the sample's origin, were extended-spectrum beta-lactamases (ESBL). Gram-negative bacteria represented 70.7% of the microbial isolates.

Finally,Table 4shows the E. coli with a high sensitivity profile to carbapenems such as meropenem, followed by ertapenem; and finally amikacin.

Sensitivity for the cephalosporin group was low; for urine samples, ceftriaxone obtained 5% while nitrofurantoin retains its high antimicrobial response. Amikacin and meropenem maintain their response to K. pneumoniae;For the TR samples, cefepime had a low response together with ciprofloxacin.

Resistance was maintained for trimethoprim/sulfamethoxazole in E. coli and for the first(Cefazolin) and third (ceftriaxone and ceftazidime) generation cephalosporins; the highest percentages of k. pneumoniae were for ampicillin/sulbactam and ceftazidime.

Finally,Table 5shows that the isolates of P. aeruginosa were sensitive to amikacin and gentamicin. The two microorganisms were fully sensitive to colistin.

Isolates of Acinetobacter baumannii complex showed high resistance to carbapenems such as meropenem and imipenem. The resistance for P. aeruginosa was 42.1% for tobramycin; 48.8% for meropenem; 53.3% for ciprofloxacin;55.6% for imipenem;55,8% for cefepime and finally 61,1% for Piperacillin/tazobactam.

Regarding te susceptibility profile of the isolated fungi, a sensitivity of more than 90% was obtained for fluconazole and voriconazole.

DISCUSSION

This study describes the microbiological profile microorganisms isolated from patients in the critical care units of the HRL from 2019 to 2020. The male sex predominated with 51.1%, compared to the studies carried out in Colombia and India. Which reported the female sex with 51.6%⁸and 64.0%⁹, respectively.

The most frequently obtained culture-positive samples were bronchial secretion and urine culture, representing more than 50% of the total, with similar results to a study conducted in Arequipa¹²; In contrast, two studies in Colombia obtained a higher frequency in blood culture samples⁸and tracheal secretion¹³. It is observed that respiratory tract infections are more prevalent at the national level than systemic infections.

A. baumannii complex and P. aeruginosa were the most frequently isolated species, unlike a study conducted in India that reported S. aureus and K. pneumoniae⁷. On the other hand, two studies in Colombia reported E. coli as the most frequent species in the critical care unit^8-13. Other studies carried out in Peru reported P. aeruginosa and E. coli as the most frequent species (Arequipa)¹²; while K. pneumoniae turned out to be the most frequent species in a hospital in Lambayeque⁹.

When analyzing the E. coli a sensitivity of 100% was obtained for meropenem and 96.3% for ertapenem, similar to a study carried out in Colombia⁸, and another in Lambayeque, where the sensitivity was more than 9 6%. for carbapenems. For the group of aminoglycosides (amikacin) the response was maintained as reported in a hospital in Lambayeque⁹.

strains E. coli presented a 94.7% resistance to ampicillin, 88,9% forcefazolin; 79,3% for trimethoprim/sulfamethoxazole with similar results in Colombia⁸.

Gram-negative bacilli, mainly enterobacteria, such as E. coli are producers of ESBL enzymes and these are capable of inactivating first and second-generation penicillins and cephalosporins, but als the plasmids that encode ESBLs carry resistance genes to other antimicrobials such as tetracyclines and co-trimoxazole, which is why the phenomenon of cross-ressitance is very frequent and the treatment of infections caused by these strains is more difficult¹⁴.

K. pneumoniae presented sensitivities greater than 84.0% for amikacin and meropenem, results that were consistent with previous studies where they presented (9, 8) percentages greater than 60.0%⁹and 100%⁸.

Likewise, there were isolates of K. pneumoniae with higher resistance levels for ampicillin/sulbactam, ceftazidime and trimethoprim/sulfamethoxazole compared to those found in studies carried out in Arequipa¹²and Colombia^8,15. ESBL production constitutes the most frequent mechanism that confers resistance to cephalosporins and other beta-lactams, except carbapenems, in the Klebsiella as shown in this research¹⁶.

Between 75.9% and 91.9% of A. baumannii complex were resistant to amikacin, gentamicin, tobramycin and trimethoprim/sulfamethoxazole, values of lower than 100% resistance for these drugs in a study conducted in Colombia¹⁷. Carbapenem resistance rates for A. baumannii complex have increased dramatically worldwide, making the antibiotic arsenal more restricted, and clinical practice shifting toward agents such as colistin¹⁸.

The resistance results obtained in the study of P. aeruginosa for cefepime were lower than the results from Arequipa¹²and Colombia⁸. For carbapenems such as meropenem and imipenem, results were well below those obtained in Arequipa¹²and India⁷. 53.3% of the isolates were resistant to ciprofloxacin, unlike the high resistance that exists in India⁷and Arequipa¹². Finally, 61.1% were resistant to piperacillin/tazobactam, while in India and Colombia the values were lower with 30.0%⁷and 50.0%⁸, respectively. While a study in Arequipa observed a higher resistance¹².

P. aeruginosa has a high level of intrinsic resistance to various antibiotics and is also capable of acquiring or inducing new resistance, significantly reducing therapeutic options. Intrinsic resistance contributes to resistance to penicillin, aminopenicillins (including combinations with β-inhibitors). lactamases),first, second and third generation cephalosporins, chloramphenicol, nitrofurantoin, sulfonamides, trimethoprim, tetracycline, and ertapenem¹⁹; however, the available therapeutic options are still effective in our environment.

Being a retrospective study, the limitations that exist are the measurement bias where the data was already measured and recorded by the microbiology laboratory service of the hospital under study. Likewise, the results have limited external validity due to the access restrictions of other hospitals that have intensive care units. However, it provides findings that will allow the initiation of new and larger studies on the subject.

CONCLUSION

In conclusion, the bacteria most frequently isolated from cultures from HRL critical care units in 2019 to 2020 were A. baumannii complex, P. aeruginosa, E. coli and K. pneumoniae. The antimicrobial susceptibility prole of A. baumannii complex showed high resistance to carbapenems and aminoglycosides, but they were sensitive to colistin, as was P. aeruginosa. Meanwhile, E. coli and K. pneumoniae were ESBL in half of their isolates, and showed high sensitivity to amikacin and meropenem.