Bacterial Isolates from Severe Infections and Their Antibiotic Susceptibility Patterns in Italy: a Nationwide Study in the Hospital Setting

Risk Identification and Mitigation of Skin and Soft Tissue Infections in Military Training Environments

OBJECTIVE

Staphylococcus aureus (SA), including methicillin-resistant strains (MRSAs), is a major cause of skin and soft tissue infections (SSTIs) in military populations. This study investigated SSTI incidence and SA carriage in a military training site over 16 weeks using a prospective observational cohort design.

METHODS

Two training cohorts provided pre- and post-training self-collected swabs for bacterial carriage, and environmental swabs from accommodations, personal items, and training facilities. Hygiene awareness and practices were assessed through questionnaires. Bacteria were identified using culture, mass spectrometry (MALDI-TOF), and genomic sequencing.

RESULTS

Nasal carriage of SA increased from 19% to 49% by the end of training. SSTIs requiring treatment occurred in 16% of participants. Steam cleaning reduced but did not eliminate SA on personal bed linen. Additionally, 40% of participants had poor knowledge of antibacterial cleaning practices and wound management.

CONCLUSIONS

Increased SA carriage was linked to human-to-human transmission in close-quarter military training environments.

IMPLICATIONS FOR PUBLIC HEALTH

Improved personal hygiene training, wound management education, and monitored cleaning protocols are essential to mitigate SSTI risks in communal military training environments.

Overall status of carbapenem resistance among clinical isolates of Acinetobacter baumannii: a systematic review and meta-analysis

BACKGROUND

Resistance to carbapenems, the first-line treatment for infections caused by Acinetobacter baumannii, is increasing throughout the world. The aim of the present study was to determine the global status of resistance to carbapenems in clinical isolates of this pathogen, worldwide.

METHODS

Electronic databases were searched using the appropriate keywords, including: 'Acinetobacter' 'baumannii', 'Acinetobacter baumannii' and 'A. baumannii', 'resistance', 'antibiotic resistance', 'antibiotic susceptibility', 'antimicrobial resistance', 'antimicrobial susceptibility', 'carbapenem', 'carbapenems', 'imipenem', 'meropenem' and 'doripenem'. Finally, following some exclusions, 177 studies from various countries were included in this study. The data were then subjected to a meta-analysis.

RESULTS

The average resistance rate of A. baumannii to imipenem, meropenem and doripenem was 44.7%, 59.4% and 72.7%, respectively. A high level of heterogeneity (I2 > 50%, P value < 0.05) was detected in the studies representing resistance to imipenem, meropenem and doripenem in A. baumannii isolates. Begg's and Egger's tests did not indicate publication bias (P value > 0.05).

CONCLUSIONS

The findings of the current study indicate that the overall resistance to carbapenems in clinical isolates of A. baumannii is relatively high and prevalent throughout the world. Moreover, time trend analysis showed that the resistance has increased from the year 2000 to 2023. This emphasizes the importance of conducting routine antimicrobial susceptibility testing before selecting a course of treatment, as well as monitoring and controlling antibiotic resistance patterns in A. baumannii strains, and seeking novel treatment options to lessen the emergence and spread of resistant strains and to reduce the treatment failure.

Global status of antimicrobial resistance in clinical Enterococcus faecalis isolates: systematic review and meta-analysis

BACKGROUND

Due to the increasing emergence of antibiotic resistance in Enterococcus faecalis (E. faecalis), it indicated as potentially opportunistic pathogen causing various healthcare-associated and life-threatening diseases around the world.

OBJECTIVE

The aim of this meta-analysis was to evaluate the weighted pooled resistance rates in clinical E. faecalis isolates based on over time, areas, antimicrobial susceptibility testing (AST), and infection source.

METHODS

We searched the studies in PubMed, Scopus, and Web of Science (November 30, 2022). All statistical analyses were carried out using the statistical package R.

RESULTS

The analysis encompassed a total of 74 studies conducted in 28 countries. According to the meta-regression, the chloramphenicol, fosfomycin, imipenem, linezolid, minocycline, norfloxacin, quinupristin-dalfopristin, and tetracycline resistance rate increased over time. Analysis revealed statistically significant differences in antibiotic resistance rates for ampicillin, chloramphenicol, erythromycin, gentamicin, penicillin, rifampicin, teicoplanin, tetracycline, and vancomycin across various countries.

CONCLUSIONS

Globally, the prevalence of drug resistant E. faecalis strains are on the increase over time. Daptomycin and tigecycline can be an effective agent for the treatment of clinical E. faecalis infections. Considering the low prevalence of antibiotic resistance in continents of Europe and Australia, it is suggested to take advantage of their preventive strategies in order to obtain efficient results in other places with high prevalence of resistance.

Clinical implications of multidrug-resistant microorganisms and fungi isolated from patients with intra-abdominal infections in the Republic of Korea: a multicenter study

The purpose of this study was to evaluate the clinical significance of fungi and multidrug-resistant organisms (MDROs) isolated from patients with intra-abdominal infections (IAIs). This multicenter study included consecutive patients admitted for microbiologically proven IAIs at 6 university-affiliated hospitals in South Korea between 2016 and 2018. A total of 1571 patients were enrolled. Multivariable logistic regression analysis revealed that the isolation of MDROs, isolation of Candida spp., underlying renal diseases, Charlson comorbidity score ≥ 3, septic shock, failure to receive a required surgery or invasive intervention, secondary bacteremia due to IAIs, and lower body mass index were found to be independent predictors for 28-day mortality. However, the isolation of Enterococcus spp. was not identified as a significant risk factor. MDROs and Candida spp. were found in 42 (2.7%) and 395 (25.1%), patients respectively. The isolation of MDROs or Candida spp. was a surrogate marker of 28-day mortality.

Epidemiology and emerging resistance in bacterial bloodstream infections in patients with hematologic malignancies

BACKGROUND

The objective of this study was determine the frequency of bloodstream infections (BSIs) and the causative bacteria and their resistance patterns in patients with hematological malignancies (HMs) in a large tertiary care university hospital in Turkey over a 5-year period.

METHODS

A total of 2098 patients with HMs with 3703 neutropenic episodes were included. Patients were classified as high-risk (n = 843) and low-risk (n = 1255) groups and evaluated for frequency of BSIs, causative bacteria, and their resistance patterns.

RESULTS

The frequency of BSIs was 14.5%. The frequency of gram-negative BSIs in high-risk and low-risk groups was 10.7% and 5.4% (p < 0.001), respectively. The frequency of gram-positive BSIs in high-risk and low-risk groups was 7.0% and 3.9% (p < 0.001), respectively. Gram-negative bacteria predominated (52.6%), with Escherichia coli (17.3%) and Klebsiella spp. (11.0%) as the most frequent organisms. Coagulase-negative staphylococci (10.4%) and Corynebacterium spp. (6.3%) were the most common gram-positive bacteria (35.8%). The rate of extended-spectrum beta-lactamase (ESBL) production was 45% for E. coli and 58% for Klebsiella spp. Quinolone resistance was 58% for E. coli and 11% for Klebsiella spp.. The overall frequency of ceftazidime resistance in Pseudomonas aeruginosa was 28%, and 87% of Acinetobacter spp. were multidrug-resistant. Of Staphylococcus aureus isolates, 24.8% were resistant to methicillin.

CONCLUSION

The dominating causes of BSIs in patients with HMs in our hospital are resistant gram-negative bacteria, which has made empirical antimicrobial choice a highly challenging issue in this patient population.

Trimethoprim/sulfamethoxazole for Acinetobacter spp.: A review of current microbiological and clinical evidence

Clinicians nowadays are confronted with an epidemic of multidrug-resistant (MDR) Acinetobacter infections and are forced to consider every treatment alternative, including older antibiotic agents, not conventionally used. This review aimed to evaluate the published evidence on the antimicrobial activity and clinical effectiveness of trimethoprim/sulfamethoxazole (TMP-SMX) against Acinetobacter spp. Selected in vitro studies included antimicrobial surveillance reports, microbiological studies regarding the activity of TMP-SMX against MDR Acinetobacter isolates, and clinical studies published after the year 2000. Non-susceptibility rates for Acinetobacter spp. in surveillance studies ranged from 4% to 98.2%; in 23 of 28 studies, non-susceptibility to TMP-SMX was >50% and in a subset of 15 studies non-susceptibility was >70%. In studies regarding MDR Acinetobacter spp., non-susceptibility rates ranged from 5.9% to 100%; however, 19 of 21 studies reported >70% non-susceptibility. Extensively drug-resistant Acinetobacter baumannii complex had total (100%) resistance in five of six studies. Carbapenem-resistant Acinetobacter spp. had non-susceptibility rates to TMP-SMX of >80% in 22 of 26 studies. One study on polymyxin-resistant A. baumannii showed a susceptibility rate of 54.2% (13/24). Only seven case reports evaluated TMP-SMX for Acinetobacter spp. infections, mainly in combination with other agents; all cases were deemed therapeutic successes. Although TMP-SMX is not usually active against Acinetobacter spp., it might be considered in cases where there are no other options.

Molecular and phenotypic characterization of methicillin-resistant Staphylococcus aureus from surgical site infections

BACKGROUND

Nosocomial infections represent an important problem for the health of hospitalized patients. Peri-operative infections--those occurring during surgery or in the post-operative period--account for 15%-20% of cases. Most surgical site infections (SSIs) are caused by endogenous gram-positive microorganisms, in particular, Staphylococcus aureus, S. epidermidis, and other coagulase-negative staphylococci that are part of the flora of the skin.

METHODS

A retrospective study was conducted from January 2006 to December 2010 to describe the epidemiology of methicillin-resistant S. aureus (MRSA) in SSIs. The MRSA isolates were analyzed by a combination of two genotyping methods: SCCmec and pulsed-field gel electrophoresis (PFGE). Also, biofilm-forming ability was analyzed for all isolates as an indicator of their ability to persist despite antibiotic treatment.

RESULTS

During the study period, 1,793 swabs from SSIs were analyzed, and S. aureus was identified in 318/987 positive specimens (32%). Methicillin resistance was observed in 10% of the S. aureus isolates (n=33). Analysis by PFGE revealed that isolates with the same SCCmec type were unrelated. Instead, biofilm-forming ability tests showed that SCCmec type I MRSA had the highest ability to form a film.

CONCLUSIONS

The strains analyzed in our study showed a homogeneous pattern of SCCmec type. The difference in ability to produce biofilm between strains of SCCmec type I and isolates with other SCCmecs was substantial. This virulence factor could have critical implications for the formation and persistence of chronic SSIs.

Bacterial isolates from infected wounds and their antibiotic susceptibility pattern: some remarks about wound infection

Wound infection plays an important role in the development of chronicity, delaying wound healing. This study aimed to identify the bacterial pathogens present in infected wounds and characterise their resistance profile to the most common antibiotics used in therapy. Three hundred and twelve wound swab samples were collected from 213 patients and analysed for the identification of microorganisms and for the determination of their antibiotic susceptibility. Patients with diverse type of wounds were included in this retrospective study, carried out from March to September 2012. A total of 28 species were isolated from 217 infected wounds. The most common bacterial species detected was Staphylococcus aureus (37%), followed by Pseudomonas aeruginosa (17%), Proteus mirabilis (10%), Escherichia coli (6%) and Corynebacterium spp. (5%). Polymicrobial infection was found in 59 (27·1%) of the samples and was mainly constituted with two species. The most common association was S. aureus/P. aeruginosa. All Gram-positives were susceptible to vancomycin and linezolid. Gram-negatives showed quite high resistance to the majority of antibiotics, being amikacin the most active against these bacteria. This study is mostly oriented to health care practitioners who deal with wound management, making them aware about the importance of wound infection and helping them to choose the adequate treatment options to control microbial infection in wounds.

Clinical experience with daptomycin in Italy: results from a registry study of the treatment of Gram-positive infections between 2006 and 2009

The purpose of this study was to evaluate post-marketing efficacy and safety data for therapy with daptomycin (DAP) in Italy. Data from patients treated with DAP at 30 centres between January 2006 and July 2009 were analysed according to the protocol of the EU-CORE(SM). In 359 patients, DAP was most commonly prescribed for skin and skin-structure infections (55%), infective endocarditis (13%), and bacteraemia (12.5%). DAP was associated with rapid improvement, and clinical success rates ranging from 77 to 91%, despite almost half of the patient population being ≥65 years of age, 86% having significant underlying disease, and many being affected by drug-resistant pathogens. Staphylococcus aureus represented 35% of all pathogens isolated. Success rates for all staphylococcal and enterococcal infections were >80%, including methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA). Clinical outcomes were similar for DAP whether used as first- or second-line therapy. DAP was well tolerated even with prolonged treatment.

Gram-positive pathogenic bacteria induce a common early response in human monocytes

BACKGROUND

We infected freshly isolated human peripheral monocytes with live bacteria of three clinically important gram-positive bacterial species, Staphylococcus aureus, Streptococcus pneumoniae and Listeria monocytogenes and studied the ensuing early transcriptional response using expression microarrays. Thus the observed response was unbiased by signals originating from other helper and effector cells of the host and was not limited to induction by solitary bacterial constituents.

RESULTS

Activation of monocytes was demonstrated by the upregulation of chemokine rather than interleukin genes except for the prominent expression of interleukin 23, marking it as the early lead cytokine. This activation was accompanied by cytoskeleton rearrangement signals and a general anti-oxidative stress and anti-apoptotic reaction. Remarkably, the expression profiles also provide evidence that monocytes participate in the regulation of angiogenesis and endothelial function in response to these pathogens.

CONCLUSION

Regardless of the invasion properties and survival mechanisms of the pathogens used, we found that the early response comprised of a consistent and common response. The common response was hallmarked by the upregulation of interleukin 23, a rather unexpected finding regarding Listeria infection, as this cytokine has been linked primarily to the control of extracellular bacterial dissemination.

Antibiotic susceptibility profiles of uncommon bacterial species causing severe infections in Italy

This study presents the results of the italian "Severe infections project" involving bacteria that can be considered rare causes of disease. we isolated 30 uncommon human pathogens from a total of 60 strains (1.2% of all the isolates). The most frequent sources of uncommon human pathogens were primary bloodstream infections (48.3%) and pneumonia (20%). Species such as Comamonas testosteroni, Enterococcus hirae, Kluyvera ascorbata, Kluyvera cryocrescens, Leclercia adecarboxylata and Ochrobactrum anthropi were recovered from bacteremia patients. Clinically useful antimicrobial agents were tested against each isolate. Resistance to 4 or more antibiotics tested was found in Achromobacter xylosoxidans, O. anthropi, Pseudomonas stutzeri, Citrobacter braakii, Enterobacter sakazakii, K. ascorbata, Proteus penneri and Serratia plymuthica. About 16% of the Gram-negative species were resistant to third-generation cephalosporins and 28.6% of the staphylococci were oxacillin-resistant. the results from this study offer indications for empirical therapy for severe infections from uncommon human pathogens.

Prophylactic use of isepamicin and levofloxacin for transrectal prostate biopsy: a retrospective single center study

OBJECTIVES

To evaluate the combination of isepamicin and levofloxacin in the prophylaxis of infectious complications associated with prostate biopsy (PBX).

METHODS

A total of 586 patients who underwent transrectal PBX in a single center were included in this retrospective analysis. They received 400 mg isepamicin once just before PBX plus 300 mg oral levofloxacin each day for three days as a rule. Clinical and laboratory data were evaluated.

RESULTS

A total of three (0.51%) patients presented a febrile complication after PBX. All of them were diagnosed as acute prostatitis. Serum white blood cell count and C-reactive protein in the 131 patients whose laboratory data were available for statistical analyses did not rise significantly after PBX.

CONCLUSIONS

Isepamicin plus fluoroquinolone can be considered a valuable regimen for antibiotic prophylaxis of PBX.

Hospital-associated methicillin-resistant Staphylococcus aureus (HA-MRSA) in Italy

The aim of our study was to trace the dynamic changes of hospital-associated methicillin-resistant Staphylococcus aureus (HA-MRSA) lineages in Italy, comparing the genotypic backgrounds of contemporary isolates over a period of 17 years, with those of a sample of early MRSA strains from 1980.

In total, 301 non-repetitive MRSA clinical isolates, recovered from 19 Italian hospitals between 1990 and 2007 were selected and analyzed for their antibiotic resistance, typed by PFGE and SCCmec, grouped into clonal-types and further characterized using Multi Locus Sequence Typing (MLST). A sample of fifteen early MRSA strains from 1980 was also used for comparison.

The most interesting feature was the recent increase of ST228-MRSA-I (formerly the Italian clone; PFGE E) over the period 2000–2007 (57%), when compared to the period 1990–1999 (29%), and its stability to date, associated with a decrease of the highly epidemic ST247-MRSA-IA (formerly the Iberian clone; PFGE A), (23% from 1990 to 1999, 6% from 2000 to 2007). ST1-MRSA-I (1 out of 2 strains carrying ccrA₂B₂), ST8-MRSA-I (4 strains), ST15-MRSA-I (1 out of 4 carrying ccrA₂B₂) and ST30-MRSA-I (2 out of 5 carrying no ccrAB-types and ccrC) were the predominant earliest STs among the MRSA strains in 1980.

A temporal shift in the susceptibility levels to glycopeptides was observed: strains with vancomycin MIC of ≥ 2 mg/L increased from 19.4% to 35.5%.

In conclusion, we describe the alternation of MRSA clones that occurred in hospitals from 1990 to 2007 and the increase of the glycopeptide MIC levels, reflecting a worldwide trend. We document the detection of ST1, ST8, ST15 and ST30 in the 1980 isolates; we hypothesize their possible latency and their appearance as the current CA-MRSA clones.

Factors associated with mortality in bacteremic patients with hematologic malignancies

We conducted a retrospective cohort study to identify risk factors for mortality in a large cohort of hematologic patients with bacteremia. From 2000 through 2005, bacteremia was diagnosed in 217 patients with hematologic malignancies. The infections were caused only by Gram-positive organisms in 57.1% (124/217) cases and only by Gram-negative bacteria in 37.8% (82/217); the remaining 5.1% (11/217) were polymicrobial. The overall 30-day mortality rate was 20.3% (44/217). In multivariate analysis, significant predictors of mortality were prolonged neutropenia (P < 0.001), acute renal failure (P = 0.002), nosocomial bacteremia (P = 0.009), age >55 years (P = 0.007), and monomicrobial bacteremia due to antibiotic-resistant Gram-negative bacteria (P = 0.009). Reducing fatal outcomes associated with bacteremia in patients with hematologic malignancies is a challenge, and the emergence of resistance to the antimicrobials widely used in this setting is of great concern. Future infection trends must be carefully monitored and treatment guidelines adjusted accordingly.

[Susceptibility patterns of Pseudomonas aeruginosa strains isolated in the Monastir region, Tunisia]

The aim of this study was to determine the susceptibility rates and patterns in P. aeruginosa strains isolated from 2002 to 2005 in a teaching Hospital of Tunisia. Susceptibility to antibiotics was assessed according to CA-SFM guidelines. During this period, 1368 strains of P. aeruginosa were identified, they were isolated mainly from pus (52.9%), respiratory samples (19.5 %), urine (10.6%), and blood cultures (5%). The percentages of resistant isolates were as follows: ticarcilline: 26.2%; ceftazidime: 21.8%; imipenem: 19.6%; gentamicin: 39.3%; amikacin: 19.2%, and ciprofloxacin: 21.6%. Nosocomial infections in P. aeruginosa are responsible for important morbidity and mortality rates, the survey of resistance to antibiotics is necessary for an efficient treatment.

Distribution, optimum detection time and antimicrobial susceptibility rates of the microorganisms isolated from blood cultures over a 4-year time period in a Turkish university hospital and a review of the international literature

This study retrospectively examined 8986 blood cultures from patients over a 4-year time period in an eastern Turkish university hospital to determine the detection times and distribution of isolated microorganisms using the automated BACTEC 9050 and BACTEC 9120 systems. A total of 1914 (21.3%) blood cultures contained pathogenic microorganisms and 252 (2.8%) positive cultures were considered contaminated. Of all the cultures, 18 (0.2%) were false positives and 224 (2.5%) were false negatives. In cultures containing pathogenic microorganisms, Gram-positive and Gram-negative bacterial isolation rates were 436 (22.8%) and 1440 (75.2%), respectively, and yeasts (all Candida sp.) were found in 38 (2.0%) cultures. Coagulase-negative staphylococci occurred in 936 (48.9%) cultures and Staphylococcus aureus occurred in 302 (15.8%) cultures. The mean detection time for all of the pathogens was 21 h and Brucella spp were isolated within 10 days. This study helps in understanding the epidemiology of the region and in providing positive therapeutic approaches. A review of the international literature helps to place this understanding into a global context.

In vitro activity of tigecycline and comparators against carbapenem-susceptible and resistant Acinetobacter baumannii clinical isolates in Italy

BACKGROUND

In a recent multi-centre Italian survey (2003-2004), conducted in 45 laboratories throughout Italy with the aim of monitoring microorganisms responsible for severe infections and their antibiotic resistance, Acinetobacter baumannii was isolated from various wards of 9 hospitals as one of the most frequent pathogens. One hundred and seven clinically significant strains of A. baumannii isolates were included in this study to determine the in vitro activity of tigecycline and comparator agents.

METHODS

Tests for the susceptibility to antibiotics were performed by the broth microdilution method as recommended by CLSI guidelines. The following antibiotics were tested: aztreonam, piperacillin/tazobactam, ampicillin/sulbactam, ceftazidime, cefepime, imipenem, meropenem tetracycline, doxycycline, tigecycline, gentamicin, amikacin, ciprofloxacin, colistin, and trimethoprim/sulphametoxazole. The PCR assay was used to determine the presence of OXA, VIM, or IMP genes in the carbapenem resistant strains.

RESULTS

A. baumannii showed widespread resistance to ceftazidime, ciprofloxacin and aztreonam in more than 90% of the strains; resistance to imipenem and meropenem was 50 and 59% respectively, amikacin and gentamicin were both active against about 30% of the strains and colistin about 99%, with only one strain resistant. By comparison with tetracyclines, tigecycline and doxycycline showed a higher activity. In particular, tigecycline showed a MIC90 value of 2 mg/L and our strains displayed a unimodal distribution of susceptibility being indistinctly active against carbapenem-susceptible and resistant strains, these latter possessed OXA-type variant enzymes.

CONCLUSION

In conclusion, tigecycline had a good activity against the MDR A. baumannii strains while maintaining the same MIC(90) of 2 mg/L against the carbapenem-resistant strains.