Antimicrobial resistance
Which bacteria cause blood infections in cancer patients, and resist drugs?
Open access · cc by · source: Europe PMC
In one Iranian cancer hospital, most blood infections were caused by gram-negative bacteria, carbapenem resistance grew each year, and about one in five patients with these infections died.
Study at a glance
- Design
- Cohort — Retrospective review of blood-culture surveillance and hospital records at one oncology hospital in Shiraz, Iran, with logistic regression for mortality and multidrug-resistance predictors.
- N
- N=414 · 414 adult patients with a positive bacterial blood culture (fungal, contaminant and polymicrobial results excluded).
- Population
- Adults aged 18 or older with haematological malignancies or solid tumours admitted to a 100-bed oncology hospital who developed bacterial bloodstream infection.
- Outcome
- Causative organisms, antibiotic susceptibility and resistance (ESBL, carbapenem resistance, multidrug resistance), mortality, and predictors of multidrug-resistant gram-negative infection.
Structured fields used in claim comparison tables when every cited study has a complete layer.
Key findings
Gram-negative bacteria caused 63.3% of infections, led by E. coli, Pseudomonas and Klebsiella pneumoniae, while coagulase-negative staphylococci were the commonest gram-positive cause. Among gram-negative infections, 39.3% were carbapenem-resistant and this rose significantly each year; nearly half met the definition of multidrug resistance. Mortality from gram-negative infections was about 20%, and no factor studied significantly predicted death. A low white-cell count and non-fermenting gram-negative bacteria (such as Pseudomonas) were linked to multidrug-resistant infection, and piperacillin-tazobactam, a standard first-line empiric drug there, performed poorly against resistant E. coli and Klebsiella.
Methodology
The researchers reviewed records of 414 adults with cancer who had a bacterial bloodstream infection at a 100-bed oncology hospital in Shiraz, Iran, between July 2015 and August 2019. They recorded patient characteristics, the bacteria grown from blood cultures, and antibiotic susceptibility from disc-diffusion testing. They then used logistic regression to look for factors linked to death and to multidrug-resistant gram-negative infection.
Limitations
Data came from one hospital, so resistance patterns may not apply elsewhere. Being retrospective, key details such as chemotherapy regimens and prior antibiotic use were often unavailable, leaving room for hidden bias in the risk-factor analyses. Carbapenemase enzyme types were not tested, and not every isolate was tested against every drug, so susceptibility percentages rest on varying denominators. The study describes associations and trends but cannot show that changing empiric therapy would reduce deaths.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
Last-line drugs are failing in first-line situations.
Carbapenem resistance in Gram-negative bloodstream isolates is already common in several low- and middle-income hospital settings: 39.3% of Gram-negative isolates in a single-hospital adult oncology cohort of 414 bloodstream infections (rising each year), and 32.6% of Klebsiella pneumoniae and 71.4% of Acinetobacter isolates in the NeoOBS neonatal sepsis cohort.
Evidence for the claim as stated.
Whether resistance itself raises mortality is design-dependent. The Tanzanian cohort found inadequate empiric cover independently predicted death, but the Brazilian case-control study (50% vs 27.5% mortality, p = 0.085, only 20 cases) and the oncology cohort (no factor significantly predicted death) could not show an independent effect, likely because of small samples and severely ill comparison groups.
Same question, contrary or null result.
Open questions
Tensions this paper is part of
From concept pages' “where studies disagree.” Disagreement means the same question; scope means different assays, populations, or outcomes.
Whether resistance itself raises mortality is design-dependent. The Tanzanian cohort found inadequate empiric cover independently predicted death, but the Brazilian case-control study (50% vs 27.5% mortality, p = 0.085, only 20 cases) and the oncology cohort (no factor significantly predicted death) could not show an independent effect, likely because of small samples and severely ill comparison groups.
History
When this study was placed
Dated entries from the concept change log — when this paper was added or removed as support, challenge, or qualifier on a claim.
Placed as supporting evidence on Antimicrobial Resistance
Carbapenem resistance in Gram-negative bloodstream isolates is already common in several low- and middle-income hospital settings: 39.3% of Gram-negative isolates in a single-hospital adult oncology cohort of 414 bloodstream infections (rising each year), and 32.6% of Klebsiella pneumoniae and 71.4% of Acinetobacter isolates in the NeoOBS neonatal sepsis cohort.
Placed as a challenge on Antimicrobial Resistance
Whether resistance itself raises mortality is design-dependent. The Tanzanian cohort found inadequate empiric cover independently predicted death, but the Brazilian case-control study (50% vs 27.5% mortality, p = 0.085, only 20 cases) and the oncology cohort (no factor significantly predicted death) could not show an independent effect, likely because of small samples and severely ill comparison groups.
Related papers in this topic
Same topic cluster — not a recommendation engine.
- How are newborns with sepsis treated, and who is most likely to die?
- Does antibiotic resistance kill children with blood infections?
- How common is isoniazid-resistant TB, and which mutations cause it?
- How has childhood shigellosis in Vietnam changed over 14 years?
- Who gets carbapenem-resistant Klebsiella, and does it kill more?