High Microbiological Spectrum Resistance Rates in Urine Isolates from Jalisco , Mexico . A Retrospective Study and Literature Review

Background: Urinary tract infections (UTIs) are a major public health problem worldwide. In Latin America, most UTIs are treated without bacteriological identification. Our aim was to examine resistance rates to commonly prescribed antibiotics, focusing on cases from Jalisco, Mexico; and additionally to conduct a review of the literature to search for resistance patterns in other countries of Latin America.


Background
Urinary tract infections (UTIs) are a major public health problem in terms of morbidity and financial cost, exceeding that of chronic renal failure [1].UTIs have been reported to affect up to 150 million individuals annually worldwide [1][2][3] and contribute to >30% of health-care facility associated infections, as annually reported by acute care hospitals [4].UTIs are one of the most common bacterial infections occurring in children and the most common bacterial infection diagnosed in women [2,5,6].Prompt recognition and correct antimicrobial management can relieve symptoms and prevent more serious sequelae, such as progressive kidney damage [5,6].Most UTIs (85%) are caused by Escherichia coli (E.Coli) and Staphylococcus saprophyticus (10%), with Klebsiella pneumoniae and the Proteus species accounting for the majority of the remaining etiologic agents [1].In up to 95% of UTI cases, treatment is prescribed without bacteriological identification, even in the presence of severe symptoms, the choice of treatment relies on local epidemiologic data coupled with empirical selection of antibiotics based upon the patient's age and gender [2].Commonly, urine samples are sent for microbiological evaluation only following treatment failure, or in presence of recurrent or relapsing infection [1].Because most UTIs are generally treated empirically, the selection of antimicrobial agent should be determined not only by the most common pathogen, but also from consideration of risk factors that may alter that pathogen´s typical susceptibility profile.One such risk factor is the production of extended spectrum beta lactamases [5,7].The acquisition of such beta lactamases may be related to changes in the bacterial genome by mutation or acquisition by horizontal transfer of extrachromosomal genetic material [8,9].
Successful invasion of the urinary tract by bacteria depends on bacterial virulence, inoculum size, defense mechanisms in the host, and for women, hormone effects and changes in the genital microbiota due to female anatomical characteristics [10,11].In cases of community-acquired (CA) UTIs (defined as those acquired prior to any hospital admission or more than 10 days after any hospital discharge) [12] the knowledge of local antimicrobial susceptibility profiles of common uropathogens is essential for prudent, empiric treatment [1].Treatment of UTIs generally includes β-lactam antibiotics, fluoroquinolones, nitrofurantoin or trimethoprim/sulfametoxazole (TMP/ SMX).Treatment varies according to patient age and gender, pathogen implicated, course of disease, and the anatomical area of the urinary tract involved [3,13].While these drugs are successful in resolving some UTIs, resistance to commonly prescribed antimicrobial agents is a matter of increasing concern.For example, fluoroquinolone resistance has been reported in various countries [3], and evidence provides an association between quinolone resistance and increased rates for prescription in the community [14].Indeed, in the span of a decade (1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007), fluoroquinolone use in Latin America has dramatically increased, with consumption rates having doubled or tripled during this period in some countries [15,16]; more importantly, a strong trend indicating increased resistance can be seen worldwide.Because of this emerging resistance problem, empiric treatments are likely to become less effective, particularly in an outpatient setting where patient follow-up may be limited or nonexistent [7].Thus, given the changing spectrum of microorganisms involved in the development of UTIs and the emergence of acquired microbial agent resistance, there is a heightened need for more rigorous patient screening to guide empiric therapy [2].Additionally, local data regarding pathogen susceptibility profiles with respect to antimicrobial agents coupled with knowledge of common UTI risk factors in a particular locale is expected to lead to better tailoring and more effective empiric treatment protocols [3].Our aim was to examine resistance rates of urine isolates to commonly prescribed antibiotics, focusing on cases in Jalisco, Mexico; additionally to conduct a review of the literature to search for resistance patterns in other countries of Latin America.

Methods
We conducted a retrospective analysis of data from the microbiology laboratory at "Unidad de Patología Clínica" (UPC), in Guadalajara, Jalisco, Mexico, which is a reference laboratory in Mexico certified by the College of American Pathologists in the Laboratory Accreditation Program since 2000.
All microbiological reports on bacterial pathogens between November 2012 and November 2013 from the state of Jalisco were included in this study.

Sample collection
In all cases, urine was collected by either clean catch method or bladder catheterization; samples were conserved at room temperature for no more than 2 hours before they were analyzed.Samples analyzed contained >25 white blood cells per microliter, and resulted in only one pathogenic micro-organism with counts of >100,000 colony forming units per milliliter.The decision to perform a urine culture was made by the attending physicians.
MicroScan panels comprise dehydrated panels for microdilution antibiotic susceptibility.Those used for ESBL detection which contains combinations of ceftazidime or cefotaxime plus β-lactamase inhibitors have received Food and Drug Administration approval; and in studies of large numbers of ESBLproducing isolates, they have appeared to be highly reliable.

Screening for ESBL producers
We used the LabPro software which is capable of identifying ESBL strains by phenotypic conformation with ceftazidime, ceftazidime/clavulanate, cefotaxime and cefotaxime/clavulanate, as recommended by the CLSI [19].Growth at or above the screening antibiotic concentration was suspicious of ESBL production and an indication for the organism to be tested by a phenotypic confirmatory test.

Statistics
For descriptive purposes, mean and standard deviation calculations were used for nominal variables and proportions for categorical variables.GraphPad Prism (5 th version) software was used for statistical analysis and figure design.

Ethics
The present study was registered and approved by the ethics committee of the "Hospital Angel Leaño, Universidad Autónoma de Guadalajara" and patient data was managed anonymously to protect privacy.

Literature review
We reviewed data from the available medical literature.A systematic search of papers was performed from data bases PUBMED, Clinical Key Elsevier, and ProQuest.We used the following search terms: "Urine culture", "Uropathogenic E. coli", "ESBL", "Antimicrobial resistance" and "Latin America".We included all papers that fall into the scope of the present review written in English and Spanish, obtained with dates from 2007 through 2014.
The proportion of adults (n=1100) was higher compared to children < 18 years of age (n=106).Among adults, 91.5% of the cases (1,006) corresponded to outpatients (OA), and 8.5% of the cases (94) were inpatients (IA).In the pediatric population 84.9% of the cases (90) were outpatients (OP) and 15.1% (16) were inpatients (IP).Age and gender comparisons from each of the four analysis groups are set forth in Table 1.

Microbiologic spectrum
The most frequent bacterial isolate in this study was ESBL-producing E. coli.The overall incidence of this pathogen was 68.3% (824/1.206),with similar proportions amongst the four analysis groups: OA (69.5%),IA (72.4%),OP (53.3%) and IP (50%); followed by non-producing ESBL E. coli.Table 2 provides the most frequently found pathogens in urine cultures.

Literature review
We found 15 different studies performed in Latin America from 2007-2014; in Mexico, data regarding the epidemiology of ESBL-producing enterobacteriaceae, most specifically, ESBL-producing E. coli, is scarce, in both outpatient and inpatient settings.
After reviewing studies performed in Latin America, we confirmed the presence of high resistance rates to commonly prescribed antimicrobial agents.

Discussion
There is a recognized significant challenge with antimicrobial resistance among important gram-negative organisms including E. coli worldwide [20].
In recent years, extended-spectrum β-lactamases (ESBLs) have increased in type and frequency, such as enterobacteriaceae and carbapenemases, which have resulted in a worldwide dissemination of such extended spectrum β-lactamases producing strains [21]; production of extended spectrum β-lactamases (ESBLs) is currently a matter of increasing global concern [5,22].Ruppe and Cols identified that the occurrence of UTI caused by ESBL E. coli in women who were not exposed to antibiotics was linked to the relative amount of fecal ESBL E. coli [23].
Results from our study echoes previous reports finding the main causative organism of UTIs to be E. coli [24].But perhaps most importantly, we found an even higher proportion of E. coli producers of ESBL in the isolates examined in here.This finding corresponds with previous studies not only in the Latin American region [15], but also from the Asia/ Pacific region (where India, China and Thailand reported the highest prevalence rates of ESBL-producing E. coli: 79.0%, 55.0% and 50.8% respectively [25]).In contrast, the results from this study differ from those conducted in other parts of the world, mainly North America and Europe; for example, in a study performed in Scotland on enterobacteriaceae isolates, only 7.5% of the isolates were phenotypically confirmed ESBL producers [26].Nevertheless, Kassakian et al [27] recently reported an increase in the prevalence of community-acquired and healthcare-associated infections in the U.S. due to ESBLproducing bacteria, particularly urinary tract infections due to ESBL-producing E. coli, with notably high resistance rates to ciprofloxacin (95%).Thus, further study of ESBL-producing enterobacterieae, particularly ESBL-producing E. coli, continues to appear highly warranted.
The discrepancies encountered in different parts of the world may be attributed to antimicrobial distribution practices.This especially holds true in countries that forego prescriptions altogether and permit sales of such drugs over-the-counter.For example, the practice in México was to sell antimicrobials over-the-counter until 2010, at which time physician prescriptions became a requirement.Importantly, some studies have identified international travel as a risk factor for the colonization by and infection with resistant E. coli [6,22,28].This finding highlights the importance of recognizing resistance patterns in different parts of the world, particularly in places where tourism attracts many international travelers.
ESBL are beta-lactamases that hydrolyze extended spectrum cephalosporins with an oxyimino side chain [6].Community acquisition of ESBLproducing E. coli was first reported in Ireland in 1998, where an ESBL producing nalidixic acidresistant uropathogenic E. coli strain was isolated from an elderly patient who did not have a recent history of hospitalization.Since then, ESBL-produ-7      cing E. coli have been increasingly reported [2,27].Over the last two decades, the proportion of community-acquired ESBL-producing E. coli strains with resistance to first-line antimicrobial agents, such as ampicillin, cephalosporins, TMP-SMX, and fluoroquinolones have increased globally, further complicating the management of UTI infections [2].While β-lactamases may be chromosomally encoded and universally present in a species or plasmid mediated, the main type of commonly found ESBL in Klebsiella and Escherichia coli are SHV-1 and SHV-2 enzymes (for sulphydral variable type 1).The second largest group of ESBLs are CTX-M enzymes.Indeed E. coli that produce CTX-M enzymes have been identified as a cause of UTIs, mainly in the community setting [29].
Various reports suggest that CTX-M-type ESBLs may now be the most frequently encountered ESBL worldwide [30].Currently, in order to establish diagnosis, a presence of 1,000 to 10,000 colony-forming units (CFU)/mL is required [4].Accordingly, physicians are encouraged to avoid prescribing antibiotics to patients with low-colony-count urine specimens, in order to decrease unnecessary exposure to antibiotics that may lead to the development of multidrug-resistant bacteria and other negative antibiotic-related conditions and side effects [4].Furthermore, fluoroquinolones are no longer the first line of treatment in cases of uncomplicated cystitis or pyelonephritis, according to both the Infectious Diseases Society of America (IDSA) and the medical guidelines published by the European Society for Microbiology and Infectious Diseases (ESCMID) [31].
The knowledge of specific risk factors for resistance development should help guide the selection of the appropriate antibiotic treatment and assist in the designing of appropriate control programs to reduce morbidity and costs related to UTIs worldwide, emphasizing the need to perform urine cultures before initiating antimicrobial treatment.This report will ideally encourage a more scientific and measured use of antibiotics which is of utmost importance, not only for patients who live in Mexico and Latin America, but also for travelers whom have acquired infections during their visits to these countries.
Our study has several potential limitations; the lack of data on clinical information, including previous antimicrobial treatments and recurrence of infection rates, due to study design, may result in information bias, although it is unlikely that this would result in differential bias.Furthermore, the antibiotic fosfomycin was not analyzed herein based on urine culture susceptibility tests that generally indicate low resistance rates for this drug.A follow-up study, incorporating additional information via informed consent permission, would be useful to establish associations between risk factors and resistance rates to specific antimicrobials.Such findings may, in turn, elucidate an alternative treatment option for uncomplicated cystitis caused by ESBL-producing E. coli infection, to minimize the current indicated use of carbapenems, which may better be reserved for more severe infections, in order to preserve its low resistance profile.

Conclusion
Data analyzed in this review is relevant to Mexico, Latin America and patients worldwide who have contracted UTIs while traveling to Mexico and other parts of Latin America, before returning to their home country.Additionally this study supports the need for improved education of health care workers regarding the use of antimicrobials as part of an international antibiotic stewardship program.Taken together, these suggested changes may not only benefit patients with UTIs, but may also go a long way to reduce the presence of antimicrobial agent resistant bacteria generally.Where Doctors exchange clinical experiences, review their cases and share clinical knowledge.You can also access lots of medical publications for free.Join Now! http://medicalia.org/

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Figure 1 :
Figure 1: Antimicrobial resistance of extended spectrum beta lactamases (ESBL) and non-ESBL E. coli to most common prescribing drugs for urinary tract infections treatment.

Table 1 .
Demographic characteristics of the study population.
OA outpatient adults, IA inpatient adults, OP outpatient pediatric, IP inpatient pediatric, SD standard deviation.butnotaselevatedasthoseforESBL-producing E. E. coli and non-ESBL E. coli is set forth in Figure1.More detailed information on ESBL and non-ESBL E. coli, Klebsiella, Morganella, and Proteus bacteria is provided in the Table4for adults and Table5for the pediatric group.

Table 2 .
Frequencies of pathogens found in urine cultures among different groups.

Table 3
summarizes different studies results performed in different countries from America with resistance rates of E. coli isolated from urine cultures.Infections comprising resistant E. coli are typically associated with increased age of patient, hospitalization, recent antibiotic use, chronic medical conditions, surgery, and immunosuppression.The high resistance rates reported in Mexico, as well as those from other studies in this region, demonstrate a need to better characterize pathogenic isolates in UTI cases.

Table 3 .
Resistance rates (%) in E. coli isolates from urine cultures in different countries of America since 2007.

Table 4 .
Antimicrobial activity against Gram-negative organisms collected from urine samples in adults from Jalisco, Mexico.