Characterization of CRISPR-Cas Systems in Shewanella algae and Shewanella haliotis: Insights into the Adaptation and Survival of Marine Pathogens.

CRISPR-Cas systems are adaptive immune mechanisms present in most prokaryotes that play an important role in the adaptation of bacteria and archaea to new environments. Shewanella algae is a marine zoonotic pathogen with worldwide distribution, which accounts for the majority of clinical cases of Shewanella infections. However, the characterization of Shewanella algae CRISPR-Cas systems has not been well investigated yet. Through whole genome sequence analysis, we characterized the CRISPR-Cas systems in S. algae. Our results indicate that CRISPR-Cas systems are prevalent in S. algae, with the majority of strains containing the Type I-F system. This study provides new insights into the diversity and function of CRISPR-Cas systems in S. algae and highlights their potential role in the adaptation and survival of these marine pathogens.

In vitro induction and selection of fluoroquinolone-resistant mutants in Elizabethkingia anophelis.

For 29 parent strains, recognized by pulsed-field gel electrophoresis, the MICs multiplied significantly in the ciprofloxacin group than levofloxacin group, following the first and third induction cycle. Ser83Arg in GyrA was the most common site of mutations. No mutation in ParC nor ParE was identified in the selected mutants.

Risk Factors and Outcomes of Community-Acquired Carbapenem-Resistant Klebsiella pneumoniae Infection in Elderly Patients.

The increasing prevalence of carbapenem-resistant Klebsiella pneumoniae (CRKP) infections is a global concern. Elderly patients have a diminished immune response and functional reserve, and are thus more vulnerable to bacterial infection. This study aimed to investigate the risk factors and outcomes in elderly patients with community-acquired CRKP infections. We performed a retrospective cohort study in a tertiary medical center between 1 January 2021, and 31 December 2021. All elderly patients who visited the emergency department during this period with culture-positive K. pneumoniae were enrolled, and their baseline demographics, laboratory profiles, management strategies, and outcomes were recorded and analyzed. We identified 528 elderly patients with K. pneumonia infection, and the proportion of patients with CRKP infection was 10.2% (54/528). Recent intensive care unit (ICU) admission and prior carbapenem use are independent risk factors for CRKP infection in elderly patients. Compared to patients with carbapenem-sensitive K. pneumoniae infection, those with CRKP infection had a significantly higher risk of adverse outcomes, including ICU care, respiratory failure, septic shock, and 90-day mortality. CRKP infection was also identified as an independent risk factor for 90-day mortality. Clinicians should be aware of the increasing prevalence of CRKP infections in elderly patients and judiciously choose appropriate antibiotics for these patients.

Time to positivity of Klebsiella pneumoniae in blood cultures as prognostic marker in patients with intra-abdominal infection: A retrospective study.

Klebsiella pneumoniae is a common causative pathogen of intra-abdominal infection with concomitant bacteraemia, leading to a significant mortality risk. The time to positivity (TTP) of blood culture is postulated to be a prognostic factor in bacteraemia caused by other species. Therefore, this study aimed to investigate the prognostic value of TTP in these patients. The single-centred, retrospective, observational cohort study was conducted between 1 July 2016 and 30 June 2021. All adult emergency department patients with diagnosis of intra-abdominal infection and underwent blood culture collection which yield K. pneumoniae during this period were enrolled. A total of 196 patients were included in the study. The overall 30-day mortality rate was 12.2% (24/196), and the median TTP of the studied cohort was 12.3 h (10.5-15.8 h). TTP revealed a moderate 30-day mortality discriminative ability (area under the curve 0.73, p < 0.001). Compared with the late TTP group (>12 h, N = 109), patients in the early TTP (≤12 h, N = 87) group had a significantly higher risk of 30-day morality (21.8% vs. 4.6%, p < 0.01) and other adverse outcomes. Furthermore, TTP (odds ratio [OR] = 0.79, p = 0.02), Pitt bacteraemia score (OR = 1.30, p = 0.03), and implementation of source control (OR = 0.06, p < 0.01) were identified as independent factors related to 30-day mortality risk in patients with intra-abdominal infection and K. pneumoniae bacteraemia. Therefore, physicians can use TTP for prognosis stratification in these patients.

Antibiotic Combination to Effectively Postpone or Inhibit the In Vitro Induction and Selection of Levofloxacin-Resistant Mutants in Elizabethkingia anophelis.

Fluoroquinolones are potentially active against Elizabethkingia anophelis. Rapidly increased minimum inhibitory concentrations (MICs) and emerging point mutations in the quinolone resistance-determining regions (QRDRs) following exposure to fluoroquinolones have been reported in E. anophelis. We aimed to investigate point mutations in QRDRs through exposure to levofloxacin (1 × MIC) combinations with different concentrations (0.5× and 1 × MIC) of minocycline, rifampin, cefoperazone/sulbactam, or sulfamethoxazole/trimethoprim in comparison with exposure to levofloxacin alone. Of the four E. anophelis isolates that were clinically collected, lower MICs of levofloxacin were disclosed in cycle 2 and 3 of induction and selection in all levofloxacin combination groups other than levofloxacin alone (all p = 0.04). Overall, no mutations were discovered in parC and parE throughout the multicycles inducted by levofloxacin and all its combinations. Regarding the vastly increased MICs, the second point mutations in gyrA and/or gyrB in one isolate (strain no. 1) occurred in cycle 2 following exposure to levofloxacin plus 0.5 × MIC minocycline, but they were delayed appearing in cycle 5 following exposure to levofloxacin plus 1 × MIC minocycline. Similarly, the second point mutation in gyrA and/or gyrB occurred in another isolate (strain no. 3) in cycle 4 following exposure to levofloxacin plus 0.5 × MIC sulfamethoxazole/trimethoprim, but no mutation following exposure to levofloxacin plus 1 × MIC sulfamethoxazole/trimethoprim was disclosed. In conclusion, the rapid selection of E. anophelis mutants with high MICs after levofloxacin exposure could be effectively delayed or postponed by antimicrobial combination with other in vitro active antibiotics.

In Vitro and In Vivo Antimicrobial Activities of Vancomycin and Rifampin against Elizabethkingia anophelis.

Elizabethkingia anophelis has emerged as a critical human pathogen, and a number of isolated reports have described the successful treatment of Elizabethkingia infections with vancomycin, a drug that is typically used to target Gram-positive bacteria. This study employed in vitro broth microdilution checkerboard and time-kill assays, as well as in vivo zebrafish animal models to evaluate the individual and combination antimicrobial effects of vancomycin and rifampin against E. anophelis. The minimum inhibitory concentration ranges of vancomycin and rifampin against 167 isolates of E. anophelis were 16-256 mg/L and 0.06-128 mg/L, respectively. The checkerboard assay results revealed a synergistic effect between vancomycin and rifampin in 16.8% (28/167) of the isolates. Time-kill assays were implemented for 66 isolates, and the two-drug combination had a synergistic interaction in 57 (86.4%) isolates. In vivo zebrafish studies revealed that treatment with vancomycin monotherapy, rifampin monotherapy, or vancomycin-rifampin combination therapy yielded a higher survival rate than the control group treatment with 0.9% saline. The results of this study support the use of vancomycin to treat E. anophelis infections.

Validation of 16S rRNA and Complete rpoB Gene Sequence Analysis for the Identification of Elizabethkingia Species.

Bacteria in the genus Elizabethkingia have emerged as a cause of life-threatening infections in humans. However, accurate species identification of these pathogens relies on molecular techniques. We aimed to evaluate the accuracy of 16S rRNA and complete RNA polymerase ß-subunit (rpoB) gene sequences in identifying Elizabethkingia species. A total of 173 Elizabethkingia strains with whole-genome sequences in GenBank were included. The 16S rRNA gene and rpoB gene sequences from the same Elizabethkingia strains were examined. Of the 41 E. meningoseptica strains, all exhibited >99.5% 16S rRNA similarity to its type strain. Only 83% of the 99 E. anophelis strains shared >99.5% 16S rRNA gene similarity with its type strain. All strains of E. meningoseptica and E. anophelis formed a cluster distinct from the other Elizabethkingia species in the 16S rRNA and rpoB gene phylogenetic trees. The polymorphisms of 16S rRNA gene sequences are not sufficient for constructing a phylogenetic tree to discriminate species in the E. miricola cluster (E. miricola, E. bruuniana, E. occulta, and E. ursingii). The complete rpoB gene phylogenetic tree clearly delineates all strains of Elizabethkingia species. The complete rpoB gene sequencing could be a useful complementary phylogenetic marker for the accurate identification of Elizabethkingia species.

Prediction of 30-Day Mortality Using the Quick Pitt Bacteremia Score in Hospitalized Patients with Klebsiella pneumoniae Infection.

Purpose: Klebsiella pneumoniae is an important causative pathogen of nosocomial infections, resulting in poor prognosis owing to its hypervirulence and antibiotic resistance. A simplified quicker version of the Pitt bacteremia score (PBS) (qPitt) for acute illness severity measurement was developed recently. The goal of this study was to explore the prognostic value of qPitt in patients with K. pneumoniae infection. Patients and Methods: Demographic information and management strategies were retrospectively collected from the records of all adult patients who visited the emergency department between January 1, 2021, and December 31, 2021, with culture-positive K. pneumoniae. The qPitt score was calculated based on: temperature <36°C, systolic blood pressure ≤90 mmHg or vasopressor administration, respiratory rate ≥25 times/min or need of mechanical ventilation, altered mental status, and cardiac arrest event. The 30-day mortality prediction abilities of the qPitt were compared with the PBS, the sequential organ failure assessment (SOFA), and the quick sequential organ failure assessment (qSOFA) using receiver operating characteristic curves. Results: Data from 867 patients (57.8% men) with a mean age of 66.9 were compiled. The 30-day mortality rate of the enrolled patients was 13.4%, and the area under the curve (AUC) of the scoring systems were as follows: SOFA, 0.91 (95% confidence interval [CI]=0.89-0.93), qPitt, 0.87 (95% CI=0.84-0.89), PBS, 0.87 (95% CI=0.85-0.89), and qSOFA, 0.73 (95% CI=0.70-0.76). The AUC of qPitt was significantly higher than that of qSOFA (p<0.01) and similar to that of PBS (p=0.65).The qPitt also demonstrated excellent mortality discrimination ability in non-bacteremic patients, AUC= 0.85 (95% CI=0.82-0.88). Conclusion: The qPitt revealed excellent 30-day mortality prediction ability and also predicted mortality in non-bacteremic patients with K. pneumoniae infection. Clinicians can use this simplified scoring system to stratify patients earlier and initiate prompt treatment in high-risk patients.

Insight into the Mechanisms of Carbapenem Resistance in Klebsiella pneumoniae: A Study on IS26 Integrons, Beta-Lactamases, Porin Modifications, and Plasmidome Analysis.

The emergence of carbapenem-resistant Klebsiella pneumoniae poses a significant threat to public health. In this study, we aimed to investigate the distribution and genetic diversity of plasmids carrying beta-lactamase resistance determinants in a collection of carbapenem-resistant K. pneumoniae blood isolates. Blood isolates of carbapenem-resistant K. pneumoniae bacteremia were collected and identified. Whole-genome sequencing, assembly and analysis were performed for the prediction of antimicrobial resistance determinants. Plasmidome analysis was also performed. Our plasmidome analysis revealed two major plasmid groups, IncFII/IncR and IncC, as key players in the dissemination of carbapenem resistance among carbapenem-resistant K. pneumoniae. Notably, plasmids within the same group exhibited conservation of encapsulated genes, suggesting that these plasmid groups may serve as conservative carriers of carbapenem-resistant determinants. Additionally, we investigated the evolution and expansion of IS26 integrons in carbapenem-resistant K. pneumoniae isolates using long-read sequencing. Our findings revealed the evolution and expansion of IS26 structure, which may have contributed to the development of carbapenem resistance in these strains. Our findings indicate that IncC group plasmids are associated with the endemic occurrence of carbapenem-resistant K. pneumoniae, highlighting the need for targeted interventions to control its spread. Although our study focuses on the endemic presence of carbapenem-resistant K. pneumoniae, it is important to note that carbapenem-resistant K. pneumoniae is indeed a global problem, with cases reported in multiple regions worldwide. Further research is necessary to better understand the factors driving the worldwide dissemination of carbapenem-resistant K. pneumoniae and to develop effective strategies for its prevention and control.

Effect of Intragenomic Sequence Heterogeneity among Multiple 16S rRNA Genes on Species Identification of Elizabethkingia.

Accurate identification of Elizabethkingia species mostly requires the use of molecular techniques, and 16S rRNA gene sequencing is generally considered the method of choice. In this study, we evaluated the effect of intraspecific diversity among the multiple copies of the 16S rRNA gene on the accuracy of species identification in the genus Elizabethkingia. Sequences of 16S rRNA genes obtained from the 32 complete whole-genome sequences of Elizabethkingia deposited in GenBank and from 218 clinical isolates collected from 5 hospitals in Taiwan were analyzed. Four or five copies of 16S rRNA were identified in the Elizabethkingia species with complete genome sequences. The dissimilarity among the copies of the16S rRNA gene was <1% in all Elizabethkingia strains. E. meningoseptica demonstrated a significantly higher rate of nucleotide variations in the 16S rRNA than did E. anophelis (P = 0.011). Nucleotide alterations occurred more frequently in regions V2 and V6 than in other hypervariable regions (P < 0.001). E. meningoseptica, E. anophelis, and E. argenteiflava strains were clustered distinctly in the phylogenetic tree inferred from 16S rRNA genes, and the intragenomic variation of gene sequences had no profound effect on the classification of taxa. However, E. miricola, E. bruuniana, E. ursingii, and E. occulta were grouped closely in the phylogenetic analysis, and the variation among the multiple copies of the 16S rRNA in one E. ursingii strain affected species classification. Other marker genes may be required to supplement the species classification of closely related taxa in the genus Elizabethkingia. IMPORTANCE Incorrect identification of bacterial species would influence the epidemiology and clinical analysis of patients infected with Elizabethkingia. The results of the present study suggest that 16S rRNA gene sequencing should not be considered the gold standard for the accurate identification of Elizabethkingia species.

Mutant Prevention Concentrations of Ciprofloxacin and Levofloxacin and Target Gene Mutations of Fluoroquinolones in Elizabethkingia anophelis.

Fluoroquinolones are potentially effective against Elizabethkingia anophelis. We investigated the MIC, mutant prevention concentration (MPC), and target gene mutations of fluoroquinolones in E. anophelis. Eighty-five E. anophelis isolates were collected from five hospitals in Taiwan. The MIC and MPC of ciprofloxacin and levofloxacin were examined for all E. anophelis except 17 isolates, in which ciprofloxacin MPC could not be determined due to drug precipitation caused by overly high drug concentration. Mutations in the quinolone resistance-determining regions of DNA gyrase (GyrA and GyrB) and topoisomerase IV (ParC and ParE) in the clinical isolates and fluoroquinolone-selected mutants were examined. Overall, 23.5% and 71.8% of the isolates tested were susceptible to ciprofloxacin and levofloxacin, respectively. The MPC50 of ciprofloxacin was 128 mg/L, and the MPC50 of levofloxacin was 51.2 mg/L. The MPC50/MIC50 ratio for ciprofloxacin was 64, whereas that for levofloxacin was 25.6. The coefficient of determination between the MPC and MIC for ciprofloxacin and levofloxacin was 0.72 and 0.56, respectively, in the linear regression analysis. Preexisting mutations in GyrA (S83I, S83R, and D87Y) were identified in 18 clinical isolates, all of which were resistant to both ciprofloxacin and levofloxacin. Additional amino acid substitutions in GyrA were identified in all ciprofloxacin- and levofloxacin-selected mutants. Furthermore, GyrB alterations (D431N or D431H) were found in nine levofloxacin-treated isolates. Given that maintaining the serum concentrations of fluoroquinolones above MPCs is impossible under presently recommended doses, the selection of mutant E. anophelis strains seems inevitable.

Genomics of Ochrobactrum pseudogrignonense (newly named Brucella pseudogrignonensis) reveals a new blaOXA subgroup.

Ochrobactrum pseudogrignonense (newly named Brucella pseudogrignonensis) is an emerging pathogen in immunodeficient and immunocompetent patients. Most documented cases associated with Ochrobactrum are frequently catheter-related and exhibit wide-spectrum ß-lactam resistance. Misidentification of this pathogen using commercial bacterial identification kits is common. We identified a case of O. pseudogrignonense infection associated with cholelithiasis. The O. pseudogrignonense genome was sequenced and reconstructed using a Nanopore and Illumina hybrid strategy. A novel blaOXA-919 divergent from existing OXA members was identified and subsequent analysis revealed its existence in all available O. pseudogrignonense genomes, which forms a new phylogenetic subgroup distinct from other OXA clusters. Further analysis demonstrated the presence of the novel blaOXA-919 in the chromosome of several other Ochrobactrum species. Our study indicated that Ochrobactrum chromosomes may be a reservoir of blaOXA-919 ß-lactamases.

Epidemiology and risk factors of scrub typhus in Taiwan: A nationwide database study from 1996 to 2014.

BACKGROUND: Scrub typhus (ST) is one of the most underdiagnosed, potentially fatal febrile diseases in the Asia-Pacific region. We conducted a comprehensive review of the risk factors of ST over 19 years using data from a nationwide database. METHODS: We used data on ST from the nationwide database of the Taiwan Centers for Disease Control from 1996 to 2014 to analyse the incidence rates and relative risks of ST according to different regions. The trends of incidence rates over the study period were also evaluated. The distribution of confirmed ST cases was mapped using geographic information system software. The characteristics of confirmed ST cases and non-ST cases (cases with suspected ST but negative test findings) were compared. RESULTS: Among the 38,127 reported cases, there were 6,791 (17.8%) confirmed ST cases. The overall incidence rate of ST in Taiwan was 1.49 per 100,000 residents per year. The trend of incidence rates increased over time. The Island region had the highest incidence rate (56.55 per 100,000 residents per year), followed by the Eastern region (15.13 per 100,000 residents per year). More confirmed ST cases were distributed in mountainous areas of Taiwan Main Island and Island region. Compared to non-ST cases, individuals with confirmed ST were younger (median [interquartile range] age: 44 [26-57] years versus 45 [30-60] years, p < .001) and more likely to engage in at-risk occupations (29.4% versus 13.3%, p < .001), including farming and animal husbandry (16.6% versus 9.0%, p < .001) and the armed forces (12.3% versus 3.5%, p < .001); however, they had a lower rate of animal contact (12.8% versus 20.1%, p < .001). CONCLUSIONS: ST is an endemic disease in Taiwan, particularly in the Island region, Eastern region and mountainous areas. Patients engaged in at-risk occupations and presenting with acute febrile diseases should undergo investigations for ST.

Antimicrobial Effects of Minocycline, Tigecycline, Ciprofloxacin, and Levofloxacin against Elizabethkingia anophelis Using In Vitro Time-Kill Assays and In Vivo Zebrafish Animal Models.

Elizabethkingia anophelis is a multidrug-resistant pathogen. This study evaluated the antimicrobial activity of minocycline, tigecycline, ciprofloxacin, and levofloxacin using in vitro time-kill assays and in vivo zebrafish animal models. The E. anophelis strain ED853-49 was arbitrarily selected from a bacterial collection which was concomitantly susceptible to minocycline, tigecycline, ciprofloxacin, and levofloxacin. The antibacterial activities of single agents at 0.5-4 × minimum inhibitory concentration (MIC) and dual-agent combinations at 2 × MIC using time-kill assays were investigated. The therapeutic effects of antibiotics in E. anophelis-infected zebrafish were examined. Both minocycline and tigecycline demonstrated bacteriostatic effects but no bactericidal effect. Minocycline at concentrations ≥2 × MIC and tigecycline at concentrations ≥3 × MIC exhibited a long-standing inhibitory effect for 48 h. Bactericidal effects were observed at ciprofloxacin and levofloxacin concentrations of ≥3 × MIC within 24 h of initial inoculation. Rapid regrowth of E. anophelis occurred after the initial killing phase when ciprofloxacin was used, regardless of the concentration. Levofloxacin treatment at the concentration of ≥2 × MIC consistently resulted in the long-lasting and sustainable inhibition of bacterial growth for 48 h. The addition of minocycline or tigecycline weakened the killing effect of fluoroquinolones during the first 10 h. The minocycline-ciprofloxacin or minocycline-levofloxacin combinations achieved the lowest colony-forming unit counts at 48 h. Zebrafish treated with minocycline or a combination of minocycline and levofloxacin had the highest survival rate (70%). The results of these in vitro and in vivo studies suggest that the combination of minocycline and levofloxacin is the most effective therapy approach for E. anophelis infection.

Shewanella algae and Morganella morganii Coinfection in Cobra-Bite Wounds: A Genomic Analysis.

Naja atra bites cause severe soft tissue injury and are prone to wound infections. The pathogens of Naja atra bite-wound infections are highly variable in different geographical regions. Here, we report the first coinfection with Shewanella algae and Morganella morganii from a Naja atra bite wound with resistome analysis using whole genome sequencing.

Comparative Analysis of Gradient Diffusion and Disk Diffusion with Agar Dilution for Susceptibility Testing of Elizabethkingia anophelis.

Elizabethkingia anophelis has recently emerged as a cause of life-threatening infections. This study compared the results of antimicrobial susceptibility testing (AST) conducted for E. anophelis through different methods. E. anophelis isolates collected between January 2005 and June 2019 were examined for their susceptibility to 14 antimicrobial agents by using disk diffusion, gradient diffusion (Etest; bioMérieux S.A., Marcy l'Etoile, France), and agar dilution methods. The agar dilution method was the reference assay. According to the agar dilution method, the isolates exhibited the highest susceptibility to minocycline (100%), doxycycline (97.6%), rifampin (95.2%), and levofloxacin (78.6%). A very major error rate of >1.5% was observed for nine antibiotics tested using the disk diffusion method. The overall categorical agreement rate between the disk diffusion and agar dilution methods was 74.8%, and ceftazidime, minocycline, levofloxacin, and rifampin met the minimum requirements for discrepancy and agreement rates. The Etest method tended to produce lower log2 minimum inhibitory concentrations for the antibiotics, except for trimethoprim-sulfamethoxazole and rifampin; the method resulted in very major errors for nine antibiotics. The overall essential and categorical agreement rates between the Etest and agar dilution methods were 67.3% and 76.1%, respectively. The Etest method demonstrated acceptable discrepancy and agreement rates for ceftazidime, minocycline, doxycycline, levofloxacin, and rifampin. AST results obtained through the disk diffusion and Etest methods for multiple antibiotics differed significantly from those obtained using the agar dilution method. These two assays should not be a routine alternative for AST for E. anophelis.

Arthrobacter woluwensis Bacteremia: A Clinical and Genomic Report.

Arthrobacter woluwensis is a Gram-positive, aerobic Actinobacteria that is widely distributed in the environment worldwide. Little is known about A. woluwensis infection and it is commonly mis-identified by culturing with commercial kits. To date, only six cases of bacteremia caused by A. woluwensis have been reported in the literature. Herein, we report a case of Arthrobacter woluwensis bacteremia in an immunocompromised host. In this case report, the results of antimicrobial susceptibility testing showed that this clinical isolate of A. woluwensis is sensitive to vancomycin, teicoplanin, but resistant to penicillin, cephalosporin and ciprofloxacin. Additionally, whole genome sequencing analysis identified common subunits of the urease system.

Coexistence of disseminated Kaposi sarcoma and multicentric Castleman disease in an HIV-infected patient under viral suppression.

Coexistence of multicentric Castleman disease and Kaposi sarcoma is rare and might be missed without an experienced pathologists' interpretation. A 46-year-old man had been diagnosed with HIV infection and treated with combination antiretroviral therapy of dolutegravir/abacavir/lamivudine (Triumeq) for one year. The latest viral load was 49 copies/mL and CD4 T-cell count was 192 cells/uL. He was admitted due to fever off and on, splenomegaly, general lymphadenopathy, and severe thrombocytopenia for two months. Biopsy of a purplish skin lesion and gastric tissue showed Kaposi sarcoma. The pathology of inguinal lymph nodes revealed coexistence of Kaposi sarcoma and multicentric Castleman disease. The plasma Kaposi sarcoma herpesvirus viral load was 365,000 copies/mL. During hospitalization, progressive pancytopenia and spiking fever persisted, and he died of multi-organ failure before completion of chemotherapeutic treatments with rituximab plus liposomal doxorubicin.

Serum C-reactive protein and procalcitonin values in acute Q fever, scrub typhus, and murine typhus.

BACKGROUND: Although C-reactive protein (CRP) and procalcitonin (PCT) are widely used inflammatory markers for infectious diseases, their role and potential application for rickettsioses were rarely studied. METHODS: A retrospective chart review and serological study were conducted in patients with rickettsioses. The clinical presentations, characteristics, laboratory data, and treatment responses were recorded and their associations with CRP and PCT values were analyzed. RESULTS: A total of 189 cases of rickettsioses, including 115 cases of acute Q fever (60.8%), 55 cases of scrub typhus (29.1%), and 19 cases of murine typhus (10.1%) were investigated. Both CRP and PCT values increased in the acute phase and declined in the convalescent phase. In the acute phase, mean CRP and PCT values were 78.2 ± 63.7 mg/L and 1.05 ± 1.40 ng/mL, respectively. Percentages of patients falling under different cut-off values of CRP and PCT were calculated systematically. Only 10.8% of CRP was > 150 mg/L and 14.2% of PCT was > 2.0 ng/mL. Patients with delayed responses to doxycycline treatment (> 3 days from treatment to defervescence) had significantly higher CRP values (102.7 ± 77.1 vs. 72.2 ± 58.2 mg/L, p = 0.041) and more PCT > 1.0 ng/ml (48.4% vs. 26.0%, p = 0.019) in the acute phase; higher CRP values (19.1 ± 37.4 vs. 3.6 ± 13.1 mg/L, p = 0.049) and more PCT > 0.5 ng/ml (19.2% vs. 1.4%, p = 0.005) in the convalescent phase. Correlation analysis was conducted for patients with acute Q fever. CRP and PCT values were positively correlated to each other, and both markers also had a positive correlation with serum aspartate transaminase values. Both CRP and PCT values and white blood cell counts were positively correlated to the days needed from doxycycline treatment to defervescence. CONCLUSION: CRP and PCT values might be useful in clinical investigations for patients with suspected rickettsioses and in predicting the response to doxycycline treatment for rickettsioses.