Antimicrobial resistance among uropathogens that cause acute uncomplicated cystitis in women in Hong Kong: a prospective multicenter study in 2006 to 2008

Antimicrobial resistance among uropathogens in the Asia-Pacific region: a systematic review

BACKGROUND

Antimicrobial resistance (AMR) in urinary tract infections (UTI) is a global public health problem. However, estimates of the prevalence of AMR, required for empirical treatment guidelines, are lacking for many regions.

OBJECTIVES

To perform a systematic review and summarize the available information about AMR prevalence among urinary Escherichia coli and Klebsiella pneumoniae, the two priority uropathogens, in the Asia-Pacific region (APAC).

METHODS

PubMed, EBSCO and Web of Science databases were searched for articles (2008-20), following PRISMA guidelines. The prevalence of resistance was calculated and reported as point estimate with 95% CI for antimicrobial drugs recommended in WHO treatment guidelines. Data were stratified by country and surveillance approach (laboratory- or population-based surveillance). The quality of included articles was assessed using a modified Newcastle-Ottawa Quality Assessment Scale.

RESULTS

Out of 2400 identified articles, 24 studies, reporting on 11 (26.8%) of the 41 APAC countries, met the inclusion criteria. Prevalence of resistance against trimethoprim/sulfamethoxazole, ciprofloxacin, and ceftriaxone ranged between 33% and 90%, with highest prevalence reported from Bangladesh, India, Sri Lanka and Indonesia. Resistance against nitrofurantoin ranged between 2.7% and 31.4%. Two studies reported data on fosfomycin resistance (1.8% and 1.7%). Quality of reporting was moderate.

CONCLUSIONS

We show very high prevalence estimates of AMR against antibiotics commonly used for the empirical treatment of UTI, in the limited number of countries in the APAC for which data are available. Novel feasible and affordable approaches that facilitate population-based AMR surveillance are needed to increase knowledge on AMR prevalence across the region.

Prevalence, serotyping and drug susceptibility patterns of Escherichia coli isolates from kidney transplanted patients with urinary tract infections

BACKGROUND

Extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (E. coli) are among the main pathogens in urinary tract infections (UTIs) among kidney transplant patients (KTPs).

AIM

To estimate the prevalence of ESBL-producing E. coli in KTPs and to evaluate the most prevalent serotypes and antibacterial susceptibility patterns of isolated bacteria in Tehran, Iran.

METHODS

A total of 60 clinical isolates of uropathogenic E. coli were collected from 3 kidney transplant centers from April to May 2019. Antimicrobial susceptibility testing was performed by the disk diffusion method as recommended by the Clinical Laboratory and Standards Institute. The serotyping of E. coli isolates was performed by the slide agglutination method. The presence of bla_TEM, bla_SHV, and bla_CTX-M genes was evaluated by polymerase chain reaction.

RESULTS

The frequency of ESBL-producing E. coli in KTPs was found to be 33.4%. All of the 60 E. coli isolates were found to be susceptible to doripenem (100%) and ertapenem (100%). High resistance rates to ampicillin (86%), cefotaxime (80%), and cefazolin (77%) were also documented. The most frequent serotypes were serotype I (50%), serotype II (15%), serotype III (25%), and serotype VI (10%). The gene most frequently found was bla_TEM (55%), followed by bla_CTX-M (51%) and bla_SHV (41%).

CONCLUSION

Molecular analysis showed that bla_TEM was the most common ESBL-encoding gene. The high resistance to β-lactams antibiotics (i.e., ampicillin, cefotaxime, and cefazolin) found in E. coli from KTPs with UTIs remains a serious clinical challenge. Further efforts to control ESBL-producing E. coli should include the careful use of all antibiotics as well as barrier precautions to reduce spread.

Escherichia coli Resistance to Fluoroquinolones in Community-Acquired Uncomplicated Urinary Tract Infection in Women: a Systematic Review

Antibiotic resistance is a threat to public health, and uncomplicated urinary tract infections (uUTIs) are an example of this concern. This systematic review (International Prospective Register of Systematic Reviews [PROSPERO] ID: CRD42020156674) is the first to determine the prevalence of Escherichia coli resistance to fluoroquinolones in women with community-acquired uUTI. PubMed and Embase searches were conducted; 38 studies fulfilled eligibility criteria and were included in the systematic review. Within Europe, ciprofloxacin resistance in E. coli isolates varied between countries and increased in some from 2006 to 2008 and 2014 to 2016, specifically in the United Kingdom (0.5% to 15.3%), Germany (8.7% to 15.1%), and Spain (22.9% to 30.8%), although methodologies and settings were often not comparable. In Asia, there was a substantial increase in ciprofloxacin resistance during 2008 to 2014 from 25% to more than 40%. In North America, resistance to ciprofloxacin also increased between 2008 and 2017, from 4% to 12%. Data exploring different age groups did not show a consistent relationship with resistance, whereas two studies found that fluoroquinolone resistance was higher in postmenopausal women than premenopausal women. One study indicated a link between fluoroquinolone resistance and uUTI recurrence. These findings may have implications for the empirical treatment of uUTI with fluoroquinolones globally, but more data are needed to fully understand regional situations and impact patient management.

Molecular Characterization of Extended-Spectrum β-Lactamase Enterobacteriaceae Isolated from Egyptian Patients with Community- and Hospital-Acquired Urinary Tract Infection

Extended-spectrum β-lactamases (ESβLs) pose a serious problem in the treatment of urinary tract infections (UTIs). The ESβL-producing organism is an expanding global health problem. Therefore, screening for ESβL, detection of their drug-resistance pattern, and molecular characterization should be a continuous process. The present study was performed to determine the antibiotic resistance profile and the genetic characterization of ESβL isolates from hospital- and community-acquired UTIs. Two hundred fifty Enterobacteriaceae isolates were obtained from urine samples of outpatient clinic attendants and hospitalized patients at Kasr Al-Aini Hospital. By phenotypic screening tests, 100 ESβL isolates were detected among the studied groups. Furthermore, detection of beta-lactamase (bla) cefotaxime (CTX)-M, sulfhydryl variable, and temoneira ESβL genes was investigated by polymerase chain reaction. A subset of 25 CTX-M-positive isolates was further identified by gene sequencing technology. Among the 100 ESβL isolates, 66% were Escherichia coli and 34% were Klebsiella spp. There was no statistical difference in the prevalence of ESβL Enterobacteriaceae in community-acquired versus hospital-acquired UTIs. The susceptibility of all ESβL isolates to carbapenems was the most prevalent finding. In addition, all ESβL E. coli isolates were susceptible to fosfomycin, whereas all community-acquired ESβL isolates were susceptible to nitrofurantoin. A total of 98% of the ESβL isolates harbored bla-CTX-M genes, with CTX-M-15 being the most prevalent. It could be concluded that ESβL production is present at a high rate among Egyptian patients with hospital- and community-acquired UTI. The high prevalence of bla-CTX-M may suggest it as a candidate for molecular screening of ESβL.

Molecular characterization of antibiotic resistant Escherichia coli isolates recovered from food samples and outpatient Clinics, KSA

Multidrug-resistant Escherichia coli is one of the most important public health concern worldwide that can be transferred through the food of animal origin to human being causing serious infection. The genetic responsibility of such resistant genes (Plasmids, integrons, and transposons) can be easily transmitted from the resistant strain to another. Therefore, the main objectives of the study is the molecular characterization of the resistant Escherichia coli isolates recovered from food samples and human isolates collected from outpatient clinics, KSA especially the resistance strains against aminoglycoside resistance genes which are responsible for the resistance against gentamicin and the resistance caused β-lactamases genes. Examination of food samples revealed 120 Escherichia coli isolates (22.22%) (30 strains O26: K60, 28 strains O128: K67, 20 strains O111: K58, 18 strains O126: K58, 10 strains O55: K59, 9 strains O86: K61 and 5 strains O157: H7). All the strains were highly resistance to penicillin, amoxicillin-clavulanic and erythromycin with a percentage of 100%, while the resistance to gentamicin, ampicillin, oxytetracycline, chloramphenicol, norfloxacin, trimethoprim, and nalidixic acid were 83%, 75%, 65.3%, 55.8%, 36.5%, 30.7% and 26.9% respectively. On the other hand, 59.6% of tested strains were sensitive to ciprofloxacin. Positive amplification of 896 bp fragments specific for aacC2 genes were observed by PCR designated for the detection of the aminoglycoside resistance genes. Meanwhile, multiplex PCR designed to detect the ampicillin and amoxicillin-clavulanic acid resistant E. coli isolates revealed positive amplification of 516 bp fragments specific for BlaTEM gene with all the resistant strains to ampicillin and amoxicillin-clavulanic acid. Moreover, positive amplification of 392 bp fragments specific for BlaSHV resistant gene were observed with (60.52%) of E. coli isolate. While all the tested strains were negative for amplification of BlaOXA_1.

Acute Pyelonephritis in Emergency Medicine Ward: A Four Years Retrospective Review

Objective

To study the characteristics of patients with acute pyelonephritis (AP) admitted to the emergency medicine ward (EMW) and sensitivity pattern of bacteria cultured from urine as well as to find out which antibiotic should be the best empirical treatment.

Methods

This was a retrospective study. All patient diagnosed with AP admitted to the EMW in Tuen Mun Hospital from January 2007 to December 2010 were included in this study. Data on patients' demographics, length of stay, urine culture and antibiotic sensitivity results as well as the types of antibiotics administered to them were collected and analysed.

Results

Altogether 308 patients were admitted to the EMW during the study period, accounting for 58% of all hospital admissions with the same diagnosis. There were comparatively more female patients (p<0.001) and fewer patients with diabetes (p<0.001) admitted to the EMW compared with other departments. The mean length of stay in EMW (2.2 days) was significantly shorter than that in other departments (7.1 days) (p<0.001). E. Coli was the commonest cultured bacterium, accounting for 94% of all positive growths. Cefuroxime sodium had high sensitivity (84%) in treating AP, which was significantly higher than that of amoxicillin-clavulanate (75%) (p<0.001). Levofloxacin also had high sensitivity (86%) but the difference between cefuroxime sodium and levofloxacin was not statistically significant (p=0.67).

Conclusions

Patients with AP admitted to local EMWs should be given either cefuroxime sodium intravenously or levofloxacin orally (if they can tolerate oral intake) as empirical treatments. Oral levofloxacin can be continued upon discharge.

Empirical treatment of lower urinary tract infections in the face of spreading multidrug resistance: in vitro study on the effectiveness of nitroxoline

The spread of antimicrobial resistance challenges the empirical treatment of urinary tract infections (UTIs). Among others, nitrofurantoin is recommended for first-line treatment, but acceptance among clinicians is limited due to chronic nitrofurantoin-induced lung toxicity and insufficient coverage of Enterobacteriaceae other than Escherichia coli. Nitroxoline appears to be an alternative to nitrofurantoin owing to its favourable safety profile, however data on its current in vitro susceptibility are sparse. In this study, susceptibility to nitroxoline was tested against 3012 urinary clinical isolates (including multidrug-resistant bacteria and Candida spp.) by disk diffusion test and/or broth microdilution. At least 91% of all Gram-negatives (n = 2000), Gram-positives (n = 403) and yeasts (n = 132) had inhibition zone diameters for nitroxoline ≥18 mm. Except for Pseudomonas aeruginosa, nitroxoline MIC₉₀ values were ≤16 mg/L and were 2- to >16-fold lower compared with nitrofurantoin. In extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae and methicillin-resistant Staphylococcus aureus (MRSA), MIC₉₀ values of nitroxoline were two-fold higher compared with non-ESBL-producing enterobacteria and methicillin-susceptible S. aureus (MSSA). The in vitro efficacies of nitroxoline and nitrofurantoin against ATCC strains of E. coli, Enterococcus faecalis and Proteus mirabilis were compared by time-kill curves in Mueller-Hinton broth and artificial urine. Nitroxoline was non-inferior against E. coli, P. mirabilis and E. faecalis in artificial urine. In conclusion, nitroxoline showed a broad antimicrobial spectrum, with inhibition zone diameters and MICs of nitroxoline well below the EUCAST breakpoint for E. coli for most organisms, and thus may also be a target for therapy of uncomplicated UTIs.

Diagnosis, Treatment, and Prevention of Urinary Tract Infection

UTI may involve the lower or upper urinary tract and may be uncomplicated or complicated. The emphasis of this chapter is uncomplicated UTI. The diagnosis of uncomplicated cystitis (bladder infection) and pyelonephritis (kidney infection) is usually easily made based on the clinical presentation, whereas the diagnosis in patients with complicated UTI is often more complex. Thus uncomplicated cystitis is usually manifested by dysuria, frequency and/or urgency without fever, and pyelonephritis is usually manifested by fever and back pain/costovertebral angle tenderness. However, pyuria is usually present with UTI, regardless of location, and its absence suggests that another condition may be causing the patient's symptoms. Treatment of cystitis is usually straightforward with one of several effective short-course antimicrobial regimens, although antimicrobial resistance continues to increase and can complicate treatment choices in certain areas. Likewise, antimicrobial resistance has complicated our management of uncomplicated pyelonephritis since resistance of uropathogens to the fluoroquinolone class, the mainstay of oral treatment for pyelonephritis, is increasing worldwide, and some of the other agents used for cystitis are not recommended for pyelonephritis due to low tissue levels. The goal of prevention of recurrent cystitis is to minimize the use of antimicrobials and there are several research efforts in progress to develop effective and safe antimicrobial-sparing preventive approaches for this common condition.

Antibiotic resistance rates and physician antibiotic prescription patterns of uncomplicated urinary tract infections in southern Chinese primary care

Uncomplicated urinary tract infections (UTI) are common in primary care. Whilst primary care physicians are called to be antimicrobial stewards, there is limited primary care antibiotic resistance surveillance and physician antibiotic prescription data available in southern Chinese primary care. The study aimed to investigate the antibiotic resistance rate and antibiotic prescription patterns in female patients with uncomplicated UTI. Factors associated with antibiotic resistance and prescription was explored. A prospective cohort study was conducted in 12 primary care group clinics in Hong Kong of patients presenting with symptoms of uncomplicated UTI from January 2012 to December 2013. Patients’ characteristics such as age, comorbidity, presenting symptoms and prior antibiotic use were recorded by physicians, as well as any empirical antibiotic prescription given at presentation. Urine samples were collected to test for antibiotic resistance of uropathogens. Univariate analysis was conducted to identify factors associated with antibiotic resistance and prescription. A total of 298 patients were included in the study. E. coli was detected in 107 (76%) out of the 141 positive urine samples. Antibiotic resistance rates of E. coli isolates for ampicillin, co-trimoxazole, ciprofloxacin, amoxicillin and nitrofurantoin were 59.8%, 31.8%, 23.4%, 1.9% and 0.9% respectively. E. coli isolates were sensitive to nitrofurantoin (98.1%) followed by amoxicillin (78.5%). The overall physician antibiotic prescription rate was 82.2%. Amoxicillin (39.6%) and nitrofurantoin (28.6%) were the most common prescribed antibiotics. Meanwhile, whilst physicians in public primary care prescribed more amoxicillin (OR: 2.84, 95% CI: 1.67 to 4.85, P<0.001) and nitrofurantoin (OR: 2.01, 95% CI: 1.14 to 3.55, P = 0.015), physicians in private clinics prescribed more cefuroxime and ciprofloxacin (P<0.05). Matching of antibiotic prescription and antibiotic sensitivity of E. coli isolates occurred in public than private primary care prescriptions (OR: 6.72, 95% CI: 2.07 to 21.80 P = 0.001) and for other uropathogens (OR: 6.19, 95% CI: 1.04 to 36.78 P = 0.034). Mismatching differences of antibiotic prescription and resistance were not evident. In conclusion, nitrofurantoin and amoxicillin should be used as first line antibiotic treatment for uncomplicated UTI. There were significant differences in antibiotic prescription patterns between public and private primary care. Public primary care practitioners were more likely to prescribe first line antibiotic treatment which match antibiotic sensitivity of E. coli isolates and other uropathogens. Further exploration of physician prescribing behaviour and educational interventions, particularly in private primary care may helpful. Meanwhile, development and dissemination of guidelines for primary care management of uncomplicated UTI as well as continued surveillance of antibiotic resistance and physician antibiotic prescription is recommended.

Extended spectrum β-lactamase producing Escherichia coli and Klebsiella pneumoniae: critical tools for antibiotic resistance pattern

Drug resistance is a phenomenon where by an organism becomes fully or partially resistant to drugs or antibiotics being used against it. Antibiotic resistance poses an exacting intimidation for people with underlying medical immune conditions or weakened immune systems. Infections caused by the enzyme extended spectrum β-lactamase (ESBL) producing multi drug resistance (MDR) Enterobacteriaceae especially Escherichia coli and Klebsiella pneumoniae are resistant to a broad range of beta lactams, including third generation cephalosporins. Among all the pathogens, these two MDR E. coli and K. pneumoniae have emerged as one of the world's greatest health threats in past two decades. The nosocomial infections caused by these ESBL producing MDR E. coli and K. pneumoniae complicated the therapy and limit treatment options.

Extended spectrum beta lactamase producing organisms causing urinary tract infections in Sri Lanka and their antibiotic susceptibility pattern -A hospital based cross sectional study

BACKGROUND

Extended Spectrum Beta- Lactamase producing organisms causing urinary tract infections (ESBL-UTI) are increasing in incidence and pose a major burden to health care. While ESBL producing Klebsiella species seem to account for most nosocomial outbreaks, ESBL-producing E. coli have been isolated from both hospitalized and non-hospitalized patients. Although 95-100% ESBL organisms are still considered sensitive to meropenem, rapid emergence of carbapenem resistance has been documented in many countries. The objective of this study was to evaluate urinary tract infections caused by ESBL producers and the antibiotic susceptibility patterns in Sri Lanka.

METHODS

Patients with confirmed ESBL-UTI admitted to Professorial Medical Unit, Colombo North Teaching Hospital from January - June 2015 were recruited to the study. Their urine culture and antibiotic susceptibility reports were evaluated after obtaining informed written consent.

RESULTS

Of 61 culture positive ESBL-UTIs, E. coli caused 53 (86.8%), followed by Klebsiella in 8 (13.1%).30 (49.1%) had a history of hospitalization within the past three months and included 6/8(75%) of Klebsiella UTI and 24/53(45.2%) of E.coli UTI. Antibiotic susceptibility of ESBL organisms were; Meropenem 58 (95%), Imipenem 45 (73.7%), Amikacin 37 (60.6%) and Nitrofurantoin 28(45.9%). In 3(4.9%), E.coli were resistant to Meropenem. These three patients had received multiple antibiotics including meropenem in the recent past for recurrent UTI.

CONCLUSIONS

We observed a higher percentage of E. coli over Klebsiella as ESBL producing organisms suggesting most ESBL-UTIs to be community acquired, Carbapenems seem to remain as the first line therapy for majority of ESBL-UTIs in the local setting. However 4.9% prevalence of meropenem resistance is alarming compared to other countries. Although prior antibiotic utilization and hospitalization may contribute to emergence of ESBL producing Klebsiella and E.coli in Sri Lanka, high prevalence of community acquired ESBL-E. coli needs further investigations to identify potential causes . Being a third world country with a free health care system, observed alarming rate of carbapenem resistance is likely to add a significant burden to health budget. We feel that treatment of infections in general needs a careful approach adhering to recommended antibiotic guidelines in order to prevent emergence of multi drug resistant organisms.

Plasmid-Mediated OqxAB Is an Important Mechanism for Nitrofurantoin Resistance in Escherichia coli

Increasing consumption of nitrofurantoin (NIT) for treatment of acute uncomplicated urinary tract infections (UTI) highlights the need to monitor emerging NIT resistance mechanisms. This study investigated the molecular epidemiology of the multidrug-resistant efflux gene oqxAB and its contribution to nitrofurantoin resistance by using Escherichia coli isolates originating from patients with UTI (n = 205; collected in 2004 to 2013) and food-producing animals (n = 136; collected in 2012 to 2013) in Hong Kong. The oqxAB gene was highly prevalent among NIT-intermediate (11.5% to 45.5%) and -resistant (39.2% to 65.5%) isolates but rare (0% to 1.7%) among NIT-susceptible (NIT-S) isolates. In our isolates, the oqxAB gene was associated with IS26 and was carried by plasmids of diverse replicon types. Multilocus sequence typing revealed that the clones of oqxAB-positive E. coli were diverse. The combination of oqxAB and nfsA mutations was found to be sufficient for high-level NIT resistance. Curing of oqxAB-carrying plasmids from 20 NIT-intermediate/resistant UTI isolates markedly reduced the geometric mean MIC of NIT from 168.9 μg/ml to 34.3 μg/ml. In the plasmid-cured variants, 20% (1/5) of isolates with nfsA mutations were NIT-S, while 80% (12/15) of isolates without nfsA mutations were NIT-S (P = 0.015). The presence of plasmid-based oqxAB increased the mutation prevention concentration of NIT from 128 μg/ml to 256 μg/ml and facilitated the development of clinically important levels of nitrofurantoin resistance. In conclusion, plasmid-mediated oqxAB is an important nitrofurantoin resistance mechanism. There is a great need to monitor the dissemination of this transferable multidrug-resistant efflux pump.

Antibiotic Resistance, Virulence, and Genetic Background of Community-Acquired Uropathogenic Escherichia coli from Algeria

The aim of the study was to investigate antibiotic resistance mechanisms, virulence traits, and genetic background of 150 nonrepetitive community-acquired uropathogenic Escherichia coli (CA-UPEC) from Algeria. A rate of 46.7% of isolates was multidrug resistant. bla genes detected were blaTEM (96.8% of amoxicillin-resistant isolates), blaCTX-M-15 (4%), overexpressed blaAmpC (4%), blaSHV-2a, blaTEM-4, blaTEM-31, and blaTEM-35 (0.7%). All tetracycline-resistant isolates (51.3%) had tetA and/or tetB genes. Sulfonamides and trimethoprim resistance genes were sul2 (60.8%), sul1 (45.9%), sul3 (6.7%), dfrA14 (25.4%), dfrA1 (18.2%), dfrA12 (16.3%), and dfrA25 (5.4%). High-level fluoroquinolone resistance (22.7%) was mediated by mutations in gyrA (S83L-D87N) and parC (S80I-E84G/V or S80I) genes. qnrB5, qnrS1, and aac(6')-Ib-cr were rare (5.3%). Class 1 and/or class 2 integrons were detected (40.7%). Isolates belonged to phylogroups B2+D (50%), A+B1 (36%), and F+C+Clade I (13%). Most of D (72.2%) and 38.6% of B2 isolates were multidrug resistant; they belong to 14 different sequence types, including international successful ST131, ST73, and ST69, reported for the first time in the community in Algeria and new ST4494 and ST4529 described in this study. Besides multidrug resistance, B2 and D isolates possessed virulence factors of colonization, invasion, and long-term persistence. The study highlighted multidrug-resistant CA-UPEC with high virulence traits and an epidemic genetic background.

Prevalence and risk factors for trimethoprim-sulfamethoxazole-resistant Escherichia coli among women with acute uncomplicated urinary tract infection in a developing country

BACKGROUND

Prospective studies from developing countries that have investigated risk factors for trimethoprim-sulfamethoxazole (TMP-SMX)-resistant Escherichia coli in women with uncomplicated urinary tract infection (UTI) remain scarce.

METHODS

Women with acute uncomplicated UTI were enrolled prospectively. Urine was sent for antimicrobial susceptibility testing. Logistic regression analysis was used to identify risk factors for TMP-SMX resistance.

RESULTS

Of 405 participants, 229 (56.5%) had bacteriuria (mean age 31.9 ± 9.5 years). In the previous 12 months, 77 (33.6%) had experienced at least one UTI episode and 106 (46.3%) reported antimicrobial use. The most common uropathogens were E. coli (75.8%) and Staphylococcus saprophyticus (8.9%). For the 179 E. coli, resistance rates were highest for ampicillin (64.3%) and TMP-SMX (41.3%). Resistance to cephalosporins, nitrofurantoin, and fluoroquinolones was much lower compared with the hospital laboratory-based surveillance data. Risk factors for TMP-SMX resistance were UTI in the last 6 months (odds ratio 2.22; p = 0.04) and the number of UTI episodes in the past year (odds ratio 2.06; p = 0.004). The number of UTI episodes (adjusted odds ratio 2.21; p = 0.02) remained significant on multivariate analysis.

CONCLUSIONS

TMP-SMX resistance was high. Number of previous UTI episodes was associated with increased risk of resistance; prior antimicrobial use was not. Hospital antibiograms should be used with caution when treating uncomplicated UTI.

High prevalence of Escherichia coli sequence type 131 among antimicrobial-resistant E. coli isolates from geriatric patients

Previous work on the subclones within Escherichia coli ST131 predominantly involved isolates from Western countries. This study assessed the prevalence and antimicrobial resistance attributed to this clonal group. A total of 340 consecutive, non-duplicated urinary E. coli isolates originating from four clinical laboratories in Hong Kong in 2013 were tested. ST131 prevalence among the total isolates was 18.5 % (63/340) and was higher among inpatient isolates (23.0 %) than outpatient isolates (11.8 %, P<0.001), and higher among isolates from patients aged ≥65 years than from patients aged 18-50 years and 51-64 years (25.4 vs 3.4 and 4.0 %, respectively, P<0.001). Of the 63 ST131 isolates, 43 (68.3 %) isolates belonged to the H30 subclone, whereas the remaining isolates belonged to H41 (n = 17), H54 (n = 2) and H22 (n = 1). All H30 isolates were ciprofloxacin-resistant, of which 18.6 % (8/43) belonged to the H30-Rx subclone. Twenty-six (41.3 %) ST131 isolates were ESBL-producers, of which 19 had blaCTX-M-14 (12 non-H30-Rx, two H30-Rx and five H41), six had blaCTX-M-15 (five non-H30-Rx and one H30-Rx) and one was blaCTX-M-negative (H30). In conclusion, ST131 accounts for a large share of the antimicrobial-resistant E. coli isolates from geriatric patients. Unlike previous reports, ESBL-producing ST131 strains mainly belonged to non-H30-Rx rather than the H30-Rx subclone, with blaCTX-M-14 as the dominant enzyme type.

Antibiotic resistance and extended spectrum beta-lactamases: Types, epidemiology and treatment

Antibiotic resistance is a problem of deep scientific concern both in hospital and community settings. Rapid detection in clinical laboratories is essential for the judicious recognition of antimicrobial resistant organisms. Production of extended-spectrum β-lactamases (ESBLs) is a significant resistance-mechanism that impedes the antimicrobial treatment of infections caused by Enterobacteriaceae and is a serious threat to the currently available antibiotic armory. ESBLs are classified into several groups according to their amino acid sequence homology. Proper infection control practices and barriers are essential to prevent spread and outbreaks of ESBL producing bacteria. As bacteria have developed different strategies to counter the effects of antibiotics, the identification of the resistance mechanism may help in the discovery and design of new antimicrobial agents. The carbapenems are widely regarded as the drugs of choice for the treatment of severe infections caused by ESBL-producing Enterobacteriaceae, although comparative clinical trials are scarce. Hence, more expeditious diagnostic testing of ESBL-producing bacteria and the feasible modification of guidelines for community-onset bacteremia associated with different infections are prescribed.

Highly conjugative IncX4 plasmids carrying blaCTX-M in Escherichia coli from humans and food animals

This study investigated the prevalence of IncX plasmid subtypes in commensal and pathogenic Escherichia coli isolates and the biological features of the IncX4 subtype. Two hundred and twenty-five E. coli isolates from multiple sources (47 chickens, 41 pigs, 30 cattle and 107 humans) obtained during the period 2006-2012 were tested for the presence of IncX1 to IncX5. Overall, the prevalence of IncX plasmids in chicken, pig, cattle and human isolates were 21.2 % (10/47), 19.5 % (8/41), 3.3 % (1/30) and 4.8 % (5/107), respectively. IncX4 was the most common subtype, followed by IncX1 and IncX3, while no IncX2 or IncX5 were found. Seven out of 16 (43.8 %) IncX4 plasmids were found to carry blaCTX-M genes and six of them originating from different host sources (four chickens, one pig and one human) had identical or highly similar RFLP patterns. Three IncX4 plasmids carrying blaCTX-M from different host sources were investigated further. It was found that the IncX4 plasmids had little effect on bacterial host growth parameters after their introduction to J53 recipients. Conjugation experiments demonstrated that the IncX4 plasmids could be efficiently transferred at 30-42 °C at rates which were generally 10(2)-10(5)-fold higher than those for the epidemic IncFII plasmid carrying blaCTX-M (pHK01). In conclusion, the IncX plasmids are more common than previously recognized. The efficient transfer of IncX4 plasmid at different temperatures and the lack of fitness burden on bacterial hosts highlight the ability of this plasmid replicon to be an important vehicle for dissemination of antimicrobial resistance.

Prevention of recurrent urinary tract infections by intravesical administration of heparin: a pilot study

OBJECTIVE

To assess the effect of bladder instillations using heparin on the rate of urinary tract infections in women resistant to standard therapy.

PATIENTS AND METHODS

The medical records of all women who received bladder instillations between May 2009 and January of 2010 at the University of Wisconsin urogynecology clinic were reviewed. Eighteen women (mean age 67 years) with a history of recurrent urinary tract infections received intravesical instillations (heparin 40,000 U, 2% lidocaine 8 ml, sodium bicarbonate 4 ml) once weekly for 6 weeks. Patients were considered resistant to standard therapy if their condition failed to respond to chronic suppression antibiotic therapy; they had chronic infections and for this reason could not be placed on chronic suppression; or they were not candidates for chronic suppression due to drug allergies. The number of urinary tract infections was monitored during treatment and for 6 months after therapy. The urinary tract infection rates were compared with the rates of urinary tract infection in the 6 months before treatment.

RESULTS

Seventy-eight percent of patients responded to therapy. Subjects were thought to have responded to therapy if there was a greater than 50% reduction in the rate of urinary tract infection. Other variables reviewed included evidence of chronic infection, hormonal status, glomerular filtration rate, age, body mass index, antibiotic allergies, diabetes, hypertension, and chronic antibiotic therapy during bladder instillations. None of these variables were found to be statistically significant.

CONCLUSION

Bladder instillations decreased the rate of urinary tract infection in this pilot study; this effect persisted into the post-treatment period. More research is needed to confirm these preliminary findings.

Prevalence and molecular epidemiology of plasmid-mediated fosfomycin resistance genes among blood and urinary Escherichia coli isolates

A total of 1878 non-duplicate clinical Escherichia coli isolates (comprising 1711 urinary isolates and 167 blood-culture isolates), which were collected from multiple centres in Hong Kong during 1996-2008, were used to investigate the prevalence and molecular epidemiology of plasmid-mediated fosfomycin (fos) resistance genes. Eighteen of the 1878 clinical E. coli isolates were fosfomycin resistant, of which six were fosA3 positive and two were positive for another fosA variant (designated fosKP96). No isolates had the fosC2 gene. The clones of the eight isolates were diverse: sequence type (ST) 95 (n = 2), ST118 (n = 1), ST131 (n = 1), ST617 (n = 1), ST648 (n = 1), ST1488 (n = 1) and ST2847 (n = 1). In the isolates, fosA3 and blaCTX-M genes were co-harboured on conjugative plasmids with F2:A-:B- (n = 2), N (n = 1), F-:A-:B1 and N (n = 1) and untypable (n = 2) replicons. Both fosKP96-carrying plasmids belonged to replicon N. RFLP analysis showed that the two F2:A-:B- plasmids carrying fosA3 and blaCTX-M-3 genes shared the same pattern. Complete sequencing of one of the two F2:A-:B- plasmids, pFOS-HK151325 (69 768 bp) demonstrated it to be >99 % identical to the previously sequenced plasmid pHK23a originating from a pig E. coli isolate in the same region. This study demonstrated the dissemination of fosA3 genes in diverse E. coli clones on multiple blaCTX-M-carrying plasmid types, of which F2:A-:B- plasmids closely related to pHK23a were shared by isolates from human and animal sources.

Global fluoroquinolone resistance epidemiology and implictions for clinical use

This paper on the fluoroquinolone resistance epidemiology stratifies the data according to the different prescription patterns by either primary or tertiary caregivers and by indication. Global surveillance studies demonstrate that fluoroquinolone resistance rates increased in the past years in almost all bacterial species except S. pneumoniae and H. influenzae, causing community-acquired respiratory tract infections. However, 10 to 30% of these isolates harbored first-step mutations conferring low level fluoroquinolone resistance. Fluoroquinolone resistance increased in Enterobacteriaceae causing community acquired or healthcare associated urinary tract infections and intraabdominal infections, exceeding 50% in some parts of the world, particularly in Asia. One to two-thirds of Enterobacteriaceae producing extended spectrum β-lactamases were fluoroquinolone resistant too. Furthermore, fluoroquinolones select for methicillin resistance in Staphylococci. Neisseria gonorrhoeae acquired fluoroquinolone resistance rapidly; actual resistance rates are highly variable and can be as high as almost 100%, particularly in Asia, whereas resistance rates in Europe and North America range from <10% in rural areas to >30% in established sexual networks. In general, the continued increase in fluoroquinolone resistance affects patient management and necessitates changes in some guidelines, for example, treatment of urinary tract, intra-abdominal, skin and skin structure infections, and traveller's diarrhea, or even precludes the use in indications like sexually transmitted diseases and enteric fever.

Current epidemiology and growing resistance of gram-negative pathogens

In the 1980s, gram-negative pathogens appeared to have been beaten by oxyimino-cephalosporins, carbapenems, and fluoroquinolones. Yet these pathogens have fought back, aided by their membrane organization, which promotes the exclusion and efflux of antibiotics, and by a remarkable propensity to recruit, transfer, and modify the expression of resistance genes, including those for extended-spectrum β-lactamases (ESBLs), carbapenemases, aminoglycoside-blocking 16S rRNA methylases, and even a quinolone-modifying variant of an aminoglycoside-modifying enzyme. Gram-negative isolates--both fermenters and non-fermenters--susceptible only to colistin and, more variably, fosfomycin and tigecycline, are encountered with increasing frequency, including in Korea. Some ESBLs and carbapenemases have become associated with strains that have great epidemic potential, spreading across countries and continents; examples include Escherichia coli sequence type (ST)131 with CTX-M-15 ESBL and Klebsiella pneumoniae ST258 with KPC carbapenemases. Both of these high-risk lineages have reached Korea. In other cases, notably New Delhi Metallo carbapenemase, the relevant gene is carried by promiscuous plasmids that readily transfer among strains and species. Unless antibiotic stewardship is reinforced, microbiological diagnosis accelerated, and antibiotic development reinvigorated, there is a real prospect that the antibiotic revolution of the 20th century will crumble.

Antibiotic resistance in urinary tract infections in college students

OBJECTIVE

To determine resistance to antibiotics of Escherichia coli in uncomplicated urinary tract infections (uUTIs) in female college students.

PARTICIPANTS

Symptomatic patients presenting to a student health service from September 2008 to December 2009.

METHODS

Clean catch midstream urine samples were tested for urinalysis (UA) and culture and sensitivity.

RESULTS

Of 168 students enrolled in the study, 138 had positive UA, and 94 of these grew >100,000 colonies/mL of E. coli. Ampicillin resistance was 31.9%, trimethoprim-sulfamethoxazole (TMP-SMX) resistance 16.0%, ciprofloxacin resistance 4.3%, amoxicillin/clavulanate resistance 3.2%, and nitrofurantoin resistance 1.1%. The sensitivity of UA was 95.4% and the positive predictive value was 87.0% (p ≤ .001). Specificity was 77.5% and negative predictive value 92.9%.

CONCLUSIONS

In healthy college women with uUTI symptoms, TMP-SMX should not be universally used for empirical therapy, whereas use of ciprofloxacin, amoxicillin/clavulanate, and nitrofurantoin are appropriate.

Urinary tract infections in the elderly population

BACKGROUND

Urinary tract infections (UTIs) are a common problem in the elderly population. The spectrum of disease varies from a relatively benign cystitis to potentially life-threatening pyelonephritis.

OBJECTIVE

This review covers the management of asymptomatic bacteriuria, acute uncomplicated cystitis, acute uncomplicated pyelonephritis, antibiotic resistance, catheter-associated bacteriuria/symptomatic UTIs, and antibiotic prophylaxis for recurrent infections in elderly men and women.

METHODS

Literature was obtained from English-language searches of MEDLINE (1966-April 2011), Cochrane Library, BIOSIS (1993-April 2011), and EMBASE (1970-April 2011). Further publications were identified from citations of resulting articles. Search terms included, but were not limited to, urinary tract infections, asymptomatic bacteriuria, acute uncomplicated cystitis, acute uncomplicated pyelonephritis, antibiotic resistance, catheter associated urinary tract infections, recurrent urinary tract infections, and elderly.

RESULTS

The prevalence of UTIs in elderly women depends on the location in which these women are living. For elderly women living in the community, UTIs compromise the second most common infection, whereas in residents of long-term care facilities (LTCFs) and hospitalized subjects, it is the number one cause of infection. The spectrum of patient presentation varies from classic signs and symptoms in the independent elderly population to atypical presentations, including increased lethargy, delirium, blunted fever response, and anorexia. Although there are few guidelines specifically directed toward the management of UTIs in the elderly population, therapy generally mirrors the recommendations for the younger adult age groups. When choosing a treatment regimen, special attention must be given to the severity of illness, living conditions, existing comorbidities, presence of external devices, local antibiotic resistance patterns, and the ability of the patient to comply with therapy.

CONCLUSIONS

Improved guidelines for the diagnosis and management of UTIs in the elderly population are needed. Better techniques to evaluate and prevent catheter-associated bacteriuria and UTIs await improved diagnostic modalities and catheter technologies. Alternative methods for prophylaxis of patients who suffer from recurrent infections must be found while minimizing the risk of developing or propagating antibiotic resistance.

Genetic identity of aminoglycoside-resistance genes in Escherichia coli isolates from human and animal sources

A bacterial collection (n=249) obtained in Hong Kong from 2002 to 2004 was used to investigate the molecular epidemiology of aminoglycoside resistance among Escherichia coli isolates from humans and food-producing animals. Of these, 89 isolates were gentamicin-sensitive (human n=60, animal n=29) and 160 isolates were gentamicin-resistant (human n=107, animal n=53). Overall, 84.1% (90/107) and 75.5% (40/53) of the gentamicin-resistant isolates from human and animal sources, respectively, were found to possess the aacC2 gene. The aacC2 gene for 20 isolates (10 each for human and animal isolates) was sequenced. Two alleles were found that were equally distributed in human and animal isolates. PFGE showed that the gentamicin-resistant isolates exhibited diverse patterns with little clonality. In some isolates, the aacC2 gene was encoded on large transferable plasmids of multiple incompatibility groups (IncF, IncI1 and IncN). An IncFII plasmid of 140 kb in size was shared by one human and three animal isolates. In summary, this study showed that human and animal isolates share the same pool of resistance genes.